Dosimetry of the Low Fluence Fast Neutron Beams for Boron Neutron Capture Therapy (붕소-중성자 포획치료를 위한 미세 속중성자 선량 특성 연구)
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- Radiation Oncology Journal
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- v.19 no.1
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- pp.66-73
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- 2001
Purpose : For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. Method and Materials : For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, ElC-1 ion chambers manufactured by A-150 plastic and used IC-l7M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was S co per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. Results : The absorbed dose of fast neutron beams was
Statement of problem: Recently, there have been increased esthetic needs for posterior dental restorations. The failure of posterior dental ceramic restoration are possible not only by the characters of the component materials but also by the type of food. Purpose: The research aim was to compare the in vitro fracture resistance of simulated first molar crowns fabricated using 4 dental ceramic systems, full-porcelain-occlusal-surfaced PFG, half-porcelain-occlusal-surfaced PFG, Empress 2, Ice Zirkon and selected Korean foods. Material and methods: Eighty axisymmetric crowns of each system were fabricated to fit a preparation with 1.5- to 2.0-mm occlusal reduction. The center of the occlusal surface on each of 15 specimens per ceramic system was axially loaded to fracture in a Instron 4465, and the maximum load(N) was recorded. Afterwards, selected Korean foods specimens(boiled crab, boiled chicken with bone, boiled beef rib, dried squid, dried anchovy, round candy, walnut shell) were prepared. 15 specimens per each food were placed under the Instron and the maximum fracture loads for them were recorded. The 95% confidence intervals of the characteristic failure load were compared between dental ceramic systems and Korean foods. Afterwards, on the basis of previous results, 14Hz cyclic load was applied on the 4 systems of dental ceramic restorations in MTS. The reults were analyzed by analysis of variance and Post Hoc tests. Results: 95% confidence intervals for mean of fracture load 1. full porcelain occlusal surfaced PFG Crown: 2599.3 to 2809.1 N 2. half porcelain occlusal surfaced PFG Crown: 3689.4 to 3819.8 N 3. Ice Zirkon Crown: 1501.2 to 1867.9 N 4. Empress 2 Crown: 803.2 to 1188.5 N 5. boiled crab: 294.1 to 367.9 N 6. boiled chicken with bone: 357.1 to 408.6 N 7. boiled beef rib: 4077.7 to 4356.0 N 8. dried squid: 147.5 to 190.5 N 9. dried anchovy: 35.6 to 46.5 N 10. round candy: 1900.5 to 2615.8 N 11. walnut shell: 85.7 to 373.1 N under cyclic load(14Hz) in MTS, fracture load and masticatory cycles are: 1. full porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 4796.8-9321.2 cycles under 2224.8 N(round candy)load, no fracture under smaller loads. 2. half porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 881705.1-1143565.7 cycles under 2224.8 N(round candy). no fracture under smaller loads. 3. Ice Zirkon Crown fractured at 95% confidence intervlas of 979993.0-1145773.4 cycles under 382.9 N(boiled chicken with bone). no fracture under smaller loads. 4. Empress 2 Crown fractured at 95% confidence intervals of 564.1-954.7 cycles under 382.9 N(boiled chicken with bone). no fracture under smaller loads. Conclusion: There was a significant difference in fracture resistance between experimental groups. Under single load, Korean foods than can cause fracture to the dental ceramic restorations are boiled beef rib and round candy. Even if there is no fracture under single load, cyclic dynamic load can fracture dental posterior ceramic crowns. Experimental data with 14 Hz dynamic cyclic load are obtained as follows. 1. PFG crown(full porcelain occlusion) was failed after mean 0.03 years under fracture load for round candy(2224.8 N). 2. PFG crown(half porcelain occlusion) was failed after mean 4.1 years under fracture load for round candy(2224.8 N). 3. Ice Zirkon crown was failed after mean 4.3 years under fracture load for boiled chicken with bone(382.9 N). 4. Empress 2 crown was failed after mean 0.003 years under fracture load for boiled chicken with bone(382.9 N).
Statement of problem: Since the concept of osseointegration in dental implants was introduced by
Experiments were conducted to study the effect of stage of maturity at harvest on the quality of silage. Herbage samples taken from the barley plant, rye plant, wheat plant, oat plant, Orchardgrass, Italian ryegrass, a mixed grass sward of Orchardgrass and Italian ryegrass and corn plant at different stages of maturity and ensiled in order to evaluate the effect of maturity on the chemical composition and feeding value as well as digestibility using sheep. Forage material were ensiled in small concrete silo. 1. The dry matter yield per 10a increased with advancing the maturity. Yield of brarley plant was 404, 635 and 900 kg at heading, milk and milk dough stage, respectively. Rye plant yield was 279, 589, 708, 10,000, 1,265, 1,376 and 1,492 kg at booting, before heading, early heading, late heading, early flowering, late flowering and after flowering stage, respectively. Italian ryegrass yield was 355, 613, 844 and 1,109 kg at vegetative, booting, heading and flowering, respectively. Orchardgrass/Italian ryegrass production was 477, 696, 891 and 1,027 kg at before was 458, 1,252, 1,534, 1,986 and 2,053 kg at tassel, early milk, yellow ripe and ripe stage, respectively. 2. Dry matter content increased with advancing maturity, but crude protein declined markedly. The NFE content decreased with advancing maturity of all the herbages except corn plant where NFE content increased, but corn plant increased. The content of crude fiber increased with advancing maturity except corn plant. The content of crude ash decreased with advancing maturity. In the rye plant, the content of neutral detergent fiber (NDF), acid detergent fiber (ADF) and cellulose increased with advancing maturity. 3. In vitro dry matter digestibilities of the rye plant was 53.6, 54.1, 50.7, 47.1, 44.9, 40.1 and 38.9% booting, before hcading, early heading, late heading, early flowering, late flowering and after flowering stage, respectively. The regression equation was
Until recently, as we recognize the significance of sustainable growth and competitiveness of small-and-medium sized enterprises (SMEs), governmental support for tangible resources such as R&D, manpower, funds, etc. has been mainly provided. However, it is also true that the inefficiency of support systems such as underestimated or redundant support has been raised because there exist conflicting policies in terms of appropriateness, effectiveness and efficiency of business support. From the perspective of the government or a company, we believe that due to limited resources of SMEs technology development and capacity enhancement through collaboration with external sources is the basis for creating competitive advantage for companies, and also emphasize value creation activities for it. This is why value chain network analysis is necessary in order to analyze inter-company deal relationships from a series of value chains and visualize results through establishing knowledge ecosystems at the corporate level. There exist Technology Opportunity Discovery (TOD) system that provides information on relevant products or technology status of companies with patents through retrievals over patent, product, or company name, CRETOP and KISLINE which both allow to view company (financial) information and credit information, but there exists no online system that provides a list of similar (competitive) companies based on the analysis of value chain network or information on potential clients or demanders that can have business deals in future. Therefore, we focus on the "Value Chain Network System (VCNS)", a support partner for planning the corporate business strategy developed and managed by KISTI, and investigate the types of embedded network-based analysis modules, databases (D/Bs) to support them, and how to utilize the system efficiently. Further we explore the function of network visualization in intelligent value chain analysis system which becomes the core information to understand industrial structure ystem and to develop a company's new product development. In order for a company to have the competitive superiority over other companies, it is necessary to identify who are the competitors with patents or products currently being produced, and searching for similar companies or competitors by each type of industry is the key to securing competitiveness in the commercialization of the target company. In addition, transaction information, which becomes business activity between companies, plays an important role in providing information regarding potential customers when both parties enter similar fields together. Identifying a competitor at the enterprise or industry level by using a network map based on such inter-company sales information can be implemented as a core module of value chain analysis. The Value Chain Network System (VCNS) combines the concepts of value chain and industrial structure analysis with corporate information simply collected to date, so that it can grasp not only the market competition situation of individual companies but also the value chain relationship of a specific industry. Especially, it can be useful as an information analysis tool at the corporate level such as identification of industry structure, identification of competitor trends, analysis of competitors, locating suppliers (sellers) and demanders (buyers), industry trends by item, finding promising items, finding new entrants, finding core companies and items by value chain, and recognizing the patents with corresponding companies, etc. In addition, based on the objectivity and reliability of the analysis results from transaction deals information and financial data, it is expected that value chain network system will be utilized for various purposes such as information support for business evaluation, R&D decision support and mid-term or short-term demand forecasting, in particular to more than 15,000 member companies in Korea, employees in R&D service sectors government-funded research institutes and public organizations. In order to strengthen business competitiveness of companies, technology, patent and market information have been provided so far mainly by government agencies and private research-and-development service companies. This service has been presented in frames of patent analysis (mainly for rating, quantitative analysis) or market analysis (for market prediction and demand forecasting based on market reports). However, there was a limitation to solving the lack of information, which is one of the difficulties that firms in Korea often face in the stage of commercialization. In particular, it is much more difficult to obtain information about competitors and potential candidates. In this study, the real-time value chain analysis and visualization service module based on the proposed network map and the data in hands is compared with the expected market share, estimated sales volume, contact information (which implies potential suppliers for raw material / parts, and potential demanders for complete products / modules). In future research, we intend to carry out the in-depth research for further investigating the indices of competitive factors through participation of research subjects and newly developing competitive indices for competitors or substitute items, and to additively promoting with data mining techniques and algorithms for improving the performance of VCNS.
A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potentially valuable resourses. As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Pinus, Quercus, and Populus grown in Korea can be enhanced by learning its physical and mechanical properties. However, the study of tree bark grown in Korea have never been undertaken. In the present paper, an investigative study is carried out on the bark of three genus, eleven species representing not only the major bark trees but major species currently grown in Korea. For each species 20 trees were selected, at Suweon and Kwang-neung areas, on the same basis of the diameter class at the proper harvesting age. One
Among the many species of bamboo, it is well known that the dwarf-type is widely distributed in the tropical regions, and the slender type in temperated zone. In the temperated zone the trees have extensively differentiated into one hundred species in 50 genera. In many oriental countries, the bamboo wood is being used as a material for construction and for the manufacture of technical instruments. The bamboo shoot is also regarded as a good and delicious edible resource. Moreover, recent medical investigation verifies that the sap of certain species of the bamboo is an antibiotic effect against cancer. Fortunately, it is very easy to propagate the bamboo trees by using cutting from southeastern Asian countries. This important resource can further be used as a significant source of pulp, which is becoming increasingly important. The classification system of this significant resource has not been completely established to date, even though its importance has been emphasized. Initiated by Canlevon Linne in the 18th century, a classification method concerning the morphological characteristics of flowers was the first step in developing a classification. But it was not an easy task to accomplish, because this type of classification system is based on the sexual organs in bamboo trees. Because the bamboo has a long life cycle of 60-120 years and classification according to this method was very difficult as the materials for the classification are not abundant and some species have changed, even though many references related to the morphological classification of bamboo trees are available nowadays. So, the certification of bamboo trees according to the morphological classification system is not reasonable for us. Consequently, the classification system of bamboo trees on the basis of endomorphological characteristics was initiated by Chinese-born Liese. And classification method based on the morphological characteristics of the vascular bundle was developed by Grosser. These classification methods are fundamentally related to Holltum's classification method, which stressed the morphology of the ovary. The author investigated to re-establish a new classification method based on the vascular sheath. Twenty-six species in 11 genera which originated from Formosa where used in the study. The results obtained from the investigation were somewhat coordinated with those of Crosser. Many difficulties were found in distinguishing the species of Bambusa and Dendrocalamus. These two species were critically differentiated under the new classification system, which is based on the existence of a separated vascular bundle sheath in the bamboo. According to these results, it is recommended that Babusa divided into two groups by placing it into either subspecies or the lower categories. This recommendation is supported by the observation that the evolutional pattern of the bamboo thunk which is from outward to inward. It is also supported by the viewpoint that the fundamental hypothesis in evolution is from simple to complex. There remained many problems to be solved through more critical examination by comparing the results to those of the classification based on the sexual organs method. The author observed the figure of the cross-sectional area of vascular trunk of bamboo tree and compared the results with those of Grosser and Liese, i.e. A,
For the purpose of utilizing the sawdust having poor combining properties as board raw material and resulting in dimensional instability of board, polypropylene chip (abbreviated below as PP chip) or oriented PP thread was combined with sawdust particle from white meranti(Shorea sp.). The PP chip was prepared from PP thread in length of 0.25, 0.5, 1.0 and 1.5 cm for conventional blending application. Thereafter, the PP chip cut as above was combined with the sawdust particle by 3, 6, 9, 12 and 15% on the weight basis of board. Oriented PP threads were aligned with spacing of 0.5, 1.0 and 1.5cm along transverse direction of board. The physical and mechanical properties on one, two and three layer boards manufactured with the above combining conditions were investigated. The conclusions obtained at this study were summarized as follows: 1. In thickness swelling, all one layer boards combined with PP chips showed lower values than control sawdustboard, and gradually clear decreasing tendendy with the increase of PP chip composition. Two layer board showed higher swelling value than one layer board, but the majority of boards lower values than control sawdustboard. All three layer boards showed lower swelling values than control sawdustboard. 2. In the PP chip and oriented thread combining board, the swelling values of boards combining 0.5cm spacing oriented thread with 1.0 or 1.5cm long PP chip in 12 and 15% by board weight were much lower than the lowest of one or three layer. 3. In specific gravity of 0.51, modulus of rupture of one layer board combined with 3% PP chip showed higher value than control sawdustboard. However, moduli of rupture of the boards with every PP chip composition did not exceed 80kgf/cm2, the low limit value of type 100 board, Korean Industrial Standard KS F 3104 Particleboards. Moduli of rupture of 6%, 1.5cm-long and 3% PP chip combined boards in specific gravity of 0.63 as well as PP chip combined board in specific gravity of 0.72 exceeded 80kgf/
The rule of the Warsaw Convention of 1929 are well known and still being all over the world. The Warsaw Convention is undoubtedly the most widely accepted private international air law treaty with some 140 countries. In the international legal system for air transportation, the Warsaw Convention has played a major role for more than half century, and has been revised many times in consideration of the rapid developments of air high technology, changes of social and economic circumstances, need for the protection of passengers. Some amendments became effective, but others are still not effective. As a result, the whole international legal system for air transportation is at past so complicated and tangled. However, the 'Warsaw system' consists of the Warsaw Convention of 1929 the Guadalajara Convention of 1961, a supplementary convention, and the following six protocols: (1) the Hague Protocol of 1955, (2) the Guatemala Protocol of 1971, (3) the Montreal Additional Protocols, No.1, (4) the Montreal Additional Protocol No.2, (5) the Montreal Additional Protocol No.3, and (6) the Montreal Additional Protocol No.4. of 1975. As a fundamental principle of the air carrier's liability in the international convention and protocols, for instance in the Warsaw Convention and the Hague Protocol, the principle of limited liability and a presumed fault system has been adopted. Subsequently, the Montreal Inter-carrier Agreement of 1966, the Guatemala City Protocol, the Montreal Additional Protocol No.3, and the Montreal Additional Protocol No. 4 of 1975 maintained the limited liability, but substituted the presumed liability system by an absolute liability, that is, strict liability system. The Warsaw System, which sets relatively low compensation limits for victims of aircraft accidents and regulates the limited liability for death and injury of air passengers, had become increasingly outdated. Japanese Airlines and Inter-carrier Agreement of International Air Transport Association in 1995 has been adopted the unlimited liability of air carrier in international flight. The IATA Inter-Carrier Agreement, in which airlines in international air transportation agree to waive the limit of damages, was long and hard in coming, but it was remarkable achievement given the political and economic realities of the world. IATA deserves enormous credit for bringing it about. The Warsaw System is controversial and questionable. In order to find rational solution to disputes between nations which adopted differing liability systems in international air transportation, we need to reform the liability of air carriers the 'Warsaw system' and fundamentally, to unify the liability system among the nations. The International Civil Aviation Organization(ICAO) will therefore reinforce its efforts to further promote a legal environment that adequately reflects the public interest and the needs of the parties involved. The ICAO Study Group met in April, 1998, together with the Drafting Committee. The time between the "Special Group on the Modernization and Consolidation of the 'Warsaw system'(SGMW)" and the Diplomatic Conference must be actively utilized to arrange for profound studies of the outstanding issues and for wide international consultations with a view to narrowing the scope of differences and preparing for a global international consensus. From 11 to 28 May 1999 the ICAO Headquarters at Montreal hosted a Diplomatic Conference convened to consider, with a view to adoption, a draft Convention intended to modernize and to integrate replace the instruments of the Warsaw system. The Council of ICAO convened this Conference under the Procedure for the Adoption of International Conventions. Some 525 participants from 121 Contracting States of ICAO attended, one non-contracting State, 11 observer delegations from international organizations, a total of 544 registered participants took part in the historic three-week conference which began on 10 May. The Conference was a success since it adopted a new Convention for the Unification of Certain Rules for International Carriage by Air. The 1999 Montreal Convention, created and signed by representatives of 52 countries at an international conference convened by ICAO at Montreal on May 28, 1999, came into effect on November 4, 2003. Representatives of 30 countries have now formally ratified the Convention under their respective national procedures and ratification of the United States, which was the 30th country to ratify, took place on September 5, 2003. Under Article 53.6 of the Montreal Convention, it enters into force on the 60th day following the deposit of the 30th instrument of ratification or acceptation. The United States' ratification was deposited with ICAO on September 5, 2003. The ICAO have succeeded in modernizing and consolidating a 70-year old system of international instruments of private international law into one legal instrument that will provide, for years to come, an adequate level of compensation for those involved in international aircraft accidents. An international diplomatic conference on air law by ICAO of 1999 succeeded in adopting a new regime for air carrier liability, replacing the Warsaw Convention and five other related legal instruments with a single convention that provided for unlimited liability in relation to passengers. Victims of international air accidents and their families will be better protected and compensated under the new Montreal Convention, which modernizes and consolidates a seventy-five year old system of international instruments of private international law into one legal instrument. A major feature of the new legal instrument is the concept of unlimited liability. Whereas the Warsaw Convention set a limit of 125,000 Gold Francs (approximately US$ 8,300) in case of death or injury to passengers, the Montreal Convention introduces a two-tier system. The first tier includes strict liability up to l00,000 Special Drawing Rights (SDR: approximately US$ 135,000), irrespective of a carrier's fault. The second tier is based on presumption of fault of a carrier and has no limit of liability. The 1999 Montreal Convention also includes the following main elements; 1. In cases of aircraft accidents, air carriers are called upon to provide advance payments, without delay, to assist entitled persons in meeting immediate economic needs; the amount of this initial payment will be subject to national law and will be deductable from the final settlement; 2. Air carriers must submit proof of insurance, thereby ensuring the availability of financial resources in cases of automatic payments or litigation; 3. The legal action for damages resulting from the death or injury of a passenger may be filed in the country where, at the time of the accident, the passenger had his or her principal and permanent residence, subject to certain conditions. The new Montreal Convention of 1999 included the 5th jurisdiction - the place of residence of the claimant. The acceptance of the 5th jurisdiction is a diplomatic victory for the US and it can be realistically expected that claimants' lawyers will use every opportunity to file the claim in the US jurisdiction - it brings advantages in the liberal system of discovery, much wider scope of compensable non-economic damages than anywhere else in the world and the jury system prone to very generous awards. 4. The facilitation in the recovery of damages without the need for lengthy litigation, and simplification and modernization of documentation related to passengers. In developing this new Montreal Convention, we were able to reach a delicate balance between the needs and interests of all partners in international civil aviation, States, the travelling public, air carriers and the transport industry. Unlike the Warsaw Convention, the threshold of l00,000 SDR specified by the Montreal Convention, as well as remaining liability limits in relation to air passengers and delay, are subject to periodic review and may be revised once every five years. The primary aim of unification of private law as well as the new Montreal Convention is not only to remove or to minimize the conflict of laws but also to avoid conflict of jurisdictions. In order to find a rational solution to disputes between nations which have adopted differing liability systems in international air transport, we need fundamentally to reform their countries's domestic air law based on the new Montreal Convention. It is a desirable and necessary for us to ratify rapidly the new Montreal Convention by the contracting states of lCAO including the Republic of Korea. According to the Korean and Japanese ideas, airlines should not only pay compensation to passengers immediately after the accident, but also the so-called 'condolence' money to the next of kin. Condolence money is a gift to help a dead person's spirit in the hereafter : it is given on account of the grief and sorrow suffered by the next of kin, and it has risen considerably over the years. The total amount of the Korean and Japanese claims in the case of death is calculated on the basis of the loss of earned income, funeral expenses and material demage (baggage etc.), plus condolence money. The economic and social change will be occurred continuously after conclusion of the new Montreal Convention. In addition, the real value of life and human right will be enhanced substantially. The amount of compensation for damage caused by aircraft accident has increased in dollar amount as well as in volume. All air carrier's liability should extend to loss of expectation of leisure activities, as well as to damage to property, and mental and physical injuries. When victims are not satisfied with the amount of the compensation for damage caused by aircraft accident for which an airline corporation is liable under the current liability system. I also would like to propose my opinion that it is reasonable and necessary for us to interpret broadly the meaning of the bodily injury on Article 17 of the new Montreal Convention so as to be included the mental injury and condolence. Furthermore, Korea and Japan has not existed the Air Transport Act regulated the civil liability of air carrier such as Air Transport Act (Luftverkehrsgestz) in Germany. It is necessary for us to enact "the Korean Air Transport Contract Act (provisional title)" in order to regulate the civil liability of air carrier including the protection of the victims and injured persons caused by aircraft accident.
Land was originally communized by a community in the primitive society of Korea, and in the age of the ancient society SAM KUK-SILLA, KOKURYOE and PAEK JE-it was distributed under the principle of land-nationalization. But by the occupation of the lands which were permitted to transmit from generation to generation as Royal Grant Lands and newly cleared lands, the private occupation had already begun to be formed. Thus the private ownership of land originated by chiefs of the tribes had a trend to be gradually pervaded to the communal members. After the, SILLA Kingdom unified SAM KUK in 668 A.D., JEONG JEON System and KWAN RYO JEON System, which were the distribution systems of farmlands originated from the TANG Dynasty in China, were enforced to established the basis of an absolute monarchy. Even in this age the forest area was jointly controlled and commonly used by village communities because of the abundance of area and stocked volume, and the private ownership of the forest land was prohibited by law under the influence of the TANG Dynasty system. Toward the end of the SILLA Dynasty, however, as its centralism become weak, the tendency of the private occupancy of farmland by influential persons was expanded, and at the same time the occupancy of the forest land by the aristocrats and Buddhist temples began to come out. In the ensuing KORYO Dynasty (519 to 1391 A.D.) JEON SI KWA System under the principle of land-nationalization was strengthened and the privilege of tax collection was transferred to the bureaucrats and the aristocrats as a means of material compensation for them. Taking this opportunity the influential persons began to expand their lands for the tax collection on a large scale. Therefore, about in the middle of 11th century the farmlands and the forest lands were annexed not only around the vicinity of the capital but also in the border area by influential persons. Toward the end of the KORYO Dynasty the royal families, the bureaucrats and the local lords all possessed manors and occupied the forest lands on a large scale as a part of their farmlands. In the KORYO Dynasty, where national economic foundation was based upon the lands, the disorder of the land system threatened the fall of the Dynasty and so the land reform carried out by General YI SEONG-GYE had led to the creation of ensuing YI Dynasty. All systems of the YI Dynasty were substantially adopted from those of the KORYO Dynasty and thereby KWA JEON System was enforced under the principle of land-nationalization, while the occupancy or the forest land was strictly prohibited, except the national or royal uses, by the forbidden item in KYEONG JE YUK JEON SOK JEON, one of codes provided by the successive kings in the YI Dynasty. Thus the basis of the forest land system through the YI Dynasty had been established, while the private forest area possessed by influential persons since the previous KORYO Dynasty was preserved continuously under the influence of their authorities. Therefore, this principle of the prohibition was nothing but a legal fiction for the security of sovereign powers. Consequently the private occupancy of the forest area was gradually enlarged and finally toward the end of YI Dynasty the privately possessed forest lands were to be officially authorized. The forest administration systems in the YI Dynasty are summarized as follows: a) KEUM SAN and BONG SAN. Under the principle of land-nationalization by a powerful centralism KWA JEON System was established at the beginning of the YI Dynasty and its government expropriated all the forests and prohibited strictly the private occupation. In order to maintain the dignity of the royal capital, the forests surounding capital areas were instituted as KEUM SAN (the reserved forests) and the well-stocked natural forest lands were chosen throughout the nation by the government as BONG SAN(national forests for timber production), where the government nominated SAN JIK(forest rangers) and gave them duties to protect and afforest the forests. This forest reservation system exacted statute labors from the people of mountainious districts and yet their commons of the forest were restricted rigidly. This consequently aroused their strong aversion against such forest reservation, therefore those forest lands were radically spoiled by them. To settle this difficult problem successive kings emphasized the preservation of the forests repeatedly, and in KYEONG KUK DAI JOEN, the written constitution of the YI Dynasty, a regulation for the forest preservation was provided but the desired results could not be obtained. Subsequently the split of bureaucrats with incessant feuds among politicians and scholars weakened the centralism and moreover, the foreign invasions since 1592 made the national land devasted and the rural communities impoverished. It happned that many wandering peasants from rural areas moved into the deep forest lands, where they cultivated burnt fields recklessly in the reserved forest resulting in the severe damage of the national forests. And it was inevitable for the government to increase the number of BONG SAN in order to solve the problem of the timber shortage. The increase of its number accelerated illegal and reckless cutting inevitably by the people living mountainuos districts and so the government issued excessive laws and ordinances to reserve the forests. In the middle of the 18th century the severe feuds among the politicians being brought under control, the excessive laws and ordinances were put in good order and the political situation became temporarily stabilized. But in spite of those endeavors evil habitudes of forest devastation, which had been inveterate since the KORYO Dynasty, continued to become greater in degree. After the conclusion of "the Treaty of KANG WHA with Japan" in 1876 western administration system began to be adopted, and thereafter through the promulgation of the Forest Law in 1908 the Imperial Forests were separated from the National Forests and the modern forest ownership system was fixed. b) KANG MU JANG. After the reorganization of the military system, attaching importance to the Royal Guard Corps, the founder of the YI Dynasty, TAI JO (1392 to 1398 A.D.) instituted the royal preserves-KANG MU JANG-to attain the purposes for military training and royal hunting, prohibiting strictly private hunting, felling and clearing by the rural inhabitants. Moreover, the tyrant, YEON SAN (1495 to 1506 A.D.), expanded widely the preserves at random and strengthened its prohibition, so KANG MU JANG had become the focus of the public antipathy. Since the invasion of Japanese in 1592, however, the innovation of military training methods had to be made because of the changes of arms and tactics, and the royal preserves were laid aside consequently and finally they had become the private forests of influential persons since 17th century. c) Forests for official use. All the forests for official use occupied by government officies since the KORYO Dynasty were expropriated by the YI Dynasty in 1392, and afterwards the forests were allotted on a fixed standard area to the government officies in need of firewoods, and as the forest resources became exhausted due to the depredated forest yield, each office gradually enlarged the allotted area. In the 17th century the national land had been almost devastated by the Japanese invasion and therefore each office was in the difficulty with severe deficit in revenue, thereafter waste lands and forest lands were allotted to government offices inorder to promote the land clearing and the increase in the collections of taxes. And an abuse of wide occupation of the forests by them was derived and there appeared a cause of disorder in the forest land system. So a provision prohibiting to allot the forests newly official use was enacted in 1672, nevertheless the government offices were trying to enlarge their occupied area by encroaching the boundary and this abuse continued up to the end of the YI Dynasty. d) Private forests. The government, at the bigninning of the YI Dynasty, expropriated the forests all over the country under the principle of prohibition of private occupancy of forest lands except for the national uses, while it could not expropriate completely all of the forest lands privately occupied and inherited successively by bureaucrats, and even local governors could not control them because of their strong influences. Accordingly the King, TAI JONG (1401 to 1418 A.D.), legislated the prohibition of private forest occupancy in his code, KYEONG JE YUK JEON (1413), and furthermore he repeatedly emphasized to observe the law. But The private occupancy of forest lands was not yet ceased up at the age of the King, SE JO (1455 to 1468 A.D.), so he prescribed the provision in KYEONG KUK DAI JEON (1474), an immutable law as a written constitution in the YI Dynasty: "Anyone who privately occupy the forest land shall be inflicted 80 floggings" and he prohibited the private possession of forest area even by princes and princesses. But, it seemed to be almost impossible for only one provsion in a code to obstruct the historical growing tendecy of private forest occupancy, for example, the King, SEONG JONG (1470 to 1494 A.D.), himself granted the forests to his royal families in defiance of the prohibition and thereafter such precedents were successively expanded, and besides, taking advantage of these facts, the influential persons openly acquired their private forest lands. After tyrannical rule of the King, YEON SAN (1945 to 1506 A.D.), the political disorder due to the splits to bureaucrats with successional feuds and the usurpations of thrones accelerated the private forest occupancy in all parts of the country, thus the forbidden clause on the private forest occupancy in the law had become merely a legal fiction since the establishment of the Dynasty. As above mentioned, after the invasion of Japanese in 1592, the courts of princes (KUNG BANGG) fell into the financial difficulties, and successive kings transferred the right of tax collection from fisherys and saltfarms to each KUNG BANG and at the same time they allotted the forest areas in attempt to promote the clearing. Availing themselves of this opportunity, royal families and bureaucrats intended to occupy the forests on large scale. Besides a privilege of free selection of grave yard, which had been conventionalized from the era of the KORYO Dynasty, created an abuse of occuping too wide area for grave yards in any forest at their random, so the King, TAI JONG, restricted the area of grave yard and homestead of each family. Under the policy of suppresion of Buddhism in the YI Dynasty a privilege of taxexemption for Buddhist temples was deprived and temple forests had to follow the same course as private forests did. In the middle of 18th century the King, YEONG JO (1725 to 1776 A.D.), took an impartial policy for political parties and promoted the spirit of observing laws by putting royal orders and regulations in good order excessively issued before, thus the confused political situation was saved, meanwhile the government officially permittd the private forest ownership which substantially had already been permitted tacitly and at the same time the private afforestation areas around the grave yards was authorized as private forests at least within YONG HO (a boundary of grave yard). Consequently by the enforcement of above mentioned policies the forbidden clause of private forest ownership which had been a basic principle of forest system in the YI Dynasty entireely remained as only a historical document. Under the rule of the King, SUN JO (1801 to 1834 A.D.), the political situation again got into confusion and as the result of the exploitation from farmers by bureaucrats, the extremely impoverished rural communities created successively wandering peasants who cleared burnt fields and deforested recklessly. In this way the devastation of forests come to the peak regardless of being private forests or national forests, moreover, the influential persons extorted private forests or reserved forests and their expansion of grave yards became also excessive. In 1894 a regulation was issued that the extorted private forests shall be returned to the initial propriators and besides taking wide area of the grave yards was prohibited. And after a reform of the administrative structure following western style, a modern forest possession system was prepared in 1908 by the forest law including a regulation of the return system of forest land ownership. At this point a forbidden clause of private occupancy of forest land got abolished which had been kept even in fictitious state since the foundation of the YI Dynasty. e) Common forests. As above mentioned, the forest system in the YI Dynasty was on the ground of public ownership principle but there was a high restriction to the forest profits of farmers according to the progressive private possession of forest area. And the farmers realized the necessity of possessing common forest. They organized village associations, SONGE or KEUM SONGE, to take the ownerless forests remained around the village as the common forest in opposition to influential persons and on the other hand, they prepared the self-punishment system for the common management of their forests. They made a contribution to the forest protection by preserving the common forests in the late YI Dynasty. It is generally known that the absolute monarchy expr opriates the widespread common forests all over the country in the process of chainging from thefeudal society to the capitalistic one. At this turning point in Korea, Japanese colonialists made public that the ratio of national and private forest lands was 8 to 2 in the late YI Dynasty, but this was merely a distorted statistics with the intention of rationalizing of their dispossession of forests from Korean owners, and they took advantage of dead forbidden clause on the private occupancy of forests for their colonization. They were pretending as if all forests had been in ownerless state, but, in truth, almost all the forest lands in the late YI Dynasty except national forests were in the state of private ownership or private occupancy regardless of their lawfulness.