• Title/Summary/Keyword: 투입구

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Reexamination of Ancient Ironmaking Technology Restoration Experiment Operating Methods (고대 제철기술 복원실험 조업방식에 대한 재검토 - 국립중원문화유산연구소 1~8차 복원실험을 중심으로 -)

  • CHOI Yeongmin;JEONG Gyeonghwa
    • Korean Journal of Heritage: History & Science
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    • v.57 no.2
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    • pp.6-25
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    • 2024
  • This study concentrated on a report on the results of smelting experiments conducted eight times by the Jungwon National Research Institute of Cultural Heritage, put together the goals and results of the operation, and examined changes in the content of experiments and in the experimental results. First, changes related to operation, such as the ratio of raw materials to fuel and the presence or absence of additives, were reviewed depending on the operation goal. In addition, the results of metallurgical analysis of raw materials, formations, and byproducts were summarized and reviewed by comparing them with materials excavated from the ruins. The operation method varied up to the eighth smelting experiment in terms of iron ore roasting, additives, and raw material/fuel ratio. After reviewing the results again, pure iron with a low carbon content began to be confirmed through metallurgical analysis. As a result, it was confirmed that the charging ratio of raw materials and fuel plays an important role depending on the purpose of production. In addition, most of the products are gray cast iron, and it was deemed that this is due to changes in the internal structure of the pig iron while it was left in the furnace for a long time. The iron was an ingot that was in a molten state even though the carbon content did not reach 4.3%, where the process reaction takes place, and it was deemed to have been caused by excessive operating temperature. Based on the previously reviewed results and the structure and shape of the experimental furnace used in other ironmaking technology restoration experiments, this study finally attempted to restore the structure of an ancient iron smelting furnace, including the furnace's upper structure. By comprehensively referring to the remaining conditions of the excavated iron smelting furnace and the characteristics of the blow pipe, the form of the ancient iron smelting furnace was subdivided into six categories: furnace wall thickness, furnace height, blower height, blow pipe size, furnace inner wall shape, and top shape, and a restoration plan was proposed. To improve the problems of the restoration plan and the Jungwon National Research Institute of Cultural Heritage's experiments that have been conducted through continuous trial and error, an experiment that reflects changes in operating methods by lowering the furnace height and controlling the blowing volume is necessary.

Changes of Pepper Yield and Chemical Properties of Soil in the Application of Different Green Manure Crops and No-Tillage Organic Cultivation (무경운 유기재배에서 녹비작물별 고추의 수량과 토양 화학성 변화)

  • Yang, Seung-Koo;Seo, Youn-Won;Kim, Yong-Soon;Kim, Sun-Kook;Lim, Kyeong-Ho;Choi, Kyung-Ju;Lee, Jeong-Hyun;Jung, Woo-Jin
    • Korean Journal of Organic Agriculture
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    • v.19 no.2
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    • pp.255-272
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    • 2011
  • This work studied the growth and yield of green crops, changes of mineral composition in greenhouse soil and green crops, and infection with wintering green crops cultivation in greenhouse field. At 74 days after seeding of wintering green crops, dry matter was 710kg/10a in rye, 530kg/10a in barley, 230kg/10a in hairy vetch, and 240kg/10a in bean or weeds. Total nitrogen content in green crops was 4.5% in pea and hairy vetch, and 3~4% in barley and rye. $P_2O_5$, CaO, and MgO contents in all green crops were about 1.0%, and $K_2O$ content was the highest level by 4~5% among macro elements. Total nitrogen fixing content in shoot green crops uptaken from soil was 22.1kg/10a in rye, 20.6kg/10a in barley, 10.6kg/10a in hairy vetch, and 9.6kg/10a in pea and giant chickweed. $P_2O_5$ fixing content in shoot green crops uptaken from soil was 8.4kg/10a in rye, 6.3kg/10a in barley, and 2.3 kg/10a in hairy vetch and pea. $K_2O$ fixing content in shoot green crops uptaken from soil was 28kg/10a in rye, 24.7kg/10a in barley, and 11kg/10a in hairy vetch and pea. CaO fixing content in shoot green crops uptaken from soil was 2~3kg/ 10a in all green crops, and MgO fixing content was 1.7~2.6kg/10a in all green crops. Pepper growth in no-tillage was not a significant difference at all green manure crops. The number of fruit and fruit weight were higher in control, pea, hairy vetch and harvest barley than rye and barley. Soil mineral compositions in wintering green crops increased at pH, organic matter, CEC compared with control. Soil chemical compositions were stable level at green crops cultivation according as decreases of EC, available phosphoric acid, Ca, and Mg contents. After no-tillage by green manure crops, pH in soils was higher in green manure crops than control. EC content in soils was lower in green manure crops than control, and was remarkably low level in barley harvest. Organic matter content in soils increased in hairy vetch and barley green manure but decreased by 35% in barley harvest. Total nitrogen and avaliable $P_2O_4$ content in soils remarkably increased but was not a significant difference at all green manure crops. Cation (K, Ca, and Mg) content in soils decreased by 15~20% in K, 2~11% in Ca, and 3~6% in Mg at rye, barley and pea compared with control.

A Study on Rationalization of National Forest Management in Korea (국유림경영(國有林經營)의 합리화(合理化)에 관(關)한 연구(硏究))

  • Choi, Kyu-Ryun
    • Journal of Korean Society of Forest Science
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    • v.20 no.1
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    • pp.1-44
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    • 1973
  • Needless to say, the management of national forest in all countries is very important in view of the national mission and management purposes. Korean national forest is also in particular significant in promoting national economy for the continuous increasing of the demand for wood, conservation of the land and social welfare. But there's no denying the fact that the leading aim of the Korean forest policy has been based upon the conservation of forest resources and recovery of land conservation function instead of improvement of the forest productive capacity. Therefore, the management of national forest should be aimed as an industry in the chain of the Korean national economy. And the increment of the forest productive capacity based on rationalized forest management is also urgently needed. Not only the increment of the timber production but also the establishment of the good forest in quality and quantity are to bring naturally many functions of conservation and other public benefits. In 1908 Korean national forest was historically established for the first time as a result of the notification for ownership, and was divided into two kinds in 1911-1924, such as indisposable national forest for land conservation, forest management, scientific research and public welfare, and the other national forest to be disposed. Indisposable forest is mostly under the jurisdiction of national forest stations (Chungbu, Tongbu, Nambu), and the tother national forests are under custody of respective cities and provinces, and under custody of the other government authorities. As of the end of 1971, national forest land is 19.5% (1,297,708 ha) of the total forest land area, but growing stock is 50.1% ($35,406,079m^3$) of the total forest growing stock, and timber production of national forest is 23.6% ($205,959m^3$) of the year production of total timber in Korea. Accordingly, it is the important fact that national forest occupies the major part of Korean forestry. The author positively affirms that success or failure of the management of national forest controls rise or fall of forestry in Korea. All functions of forest are very important, but among others the function of timber production is most important especially in Korea, that unavoidably imports a large quantity of foreign wood every year (in 1971 import of foreign wood-$3,756,000m^3$, 160,995,000 dollars). So, Korea urgently needs the improvement of forest productive capacity in national forest. But it is difficult that wood production meets the rapid increase of demand for wood to the development of economy, because production term of forestry is long, so national forest management should be rationalized by the effective investment and development of forestry techniques in the long view. Although Korean national forest business has many difficulties in the budget, techniques and the lack of labour due to outflow of rural village labour by development of national economy, and the increase of labour wages and administrative expenses etc. the development of national forest depends on adoption of the suitable forest techniques and management adapted for social and economical development. In this view point the writer has investigated and analyzed the status of the management of national forest in Korea to examine the irrational problems and suggest an improvement plan. The national forestry statistics cited in this study is based on the basic statistics and the statistics of the forest business as of the end of 1971 published by Office of Forestry, Republic of Korea, and the other depended on the data presented by the national forest stations. The writer wants to propose as follows (seemed to be helpful in improvement of Korean national forest management). 1) In the organization of national forest management, more national forest stations should be established to manage intensively, and the staff of working plan officials should be strengthened because of the importance of working plan. 2) By increasing the staff of protection officials, forest area assigned for each protection official should be decreased to 1,000-2,000 ha. 3) The frequent personnel changes of supervisor of national forest station(the responsible person on-the-spot) obstructs to accomplish the consistent management plan. 4) In the working plan drafting for national forest, basic investigations should be carefully practiced with sufficient expenditure and staff not to draft unreal working plan. 5) The area of working-unit should be decreased to less than 2,000 ha on the average for intensive management and the principle of a working-unit in a forest station should be realized as soon as possible. 6) Reforestation on open land should be completed in a short time with a debt of the special fund(a long term loan), and the land on which growing hardwood stands should be changed with conifers to increase productivity per unit area, and at the same time techical utilization method of hardwood should be developed. 7) Expenses of reforestation should be saved by mechanization and use of chemicals for reforestation and tree nursery operation providing against the lack of labour in future. 8) In forest protection, forest fire damage is enormous in comparison with foreign countries, accordingly prevention system and equipment should be improved, and also the minimum necessary budget should be counted up for establishment and manintenance of fire-lines. 9) Manufacture production should be enlarged to systematize protection, processing and circulation of forest business, and, by doing this, mich benefit is naturally given for rural people. 10) Establishment and arrangement of forest road networks and erosion control work are indispensable for the future development of national forest itself and local development. Therefore, these works should be promoted by the responsibility of general accounting instead of special accounting. 11) Mechanization of forest works should be realized for exploiting hinterlands to meet the demand for timber increased and for solving lack of labour, consequently it should promote import of forest machines, home production, training for operaters and careful adminitration. 12) Situation of labour in future will grow worse. Therefore, the countermeasure to maintain forest labourers and pay attention to public welfare facilities and works should be considered. 13) Although the condition of income and expenditure grows worse because of economical change, the regular expenditure should be fixed. So part of the surplus fund, as of the end of 1971, should be established for the fund, and used for enlarging reforestation and forest road networks(preceding investment in national forest).

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