• The Korean Journal of Air & Space Law and Policy
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• v.25 no.2
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• pp.201-230
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• 2010

With starting the industry of automobiles, railroads and mining, the legal principle of "erlaubtes Risiko" that began as a means of maintaining the revitalized world for the cause of social utility has interpreted as a system of negligence theory in the precedent while it has gained academic recognition. Yet in aircraft operation, which is one area of high technology, CAT which can be the cause of some accidents or events or thunderstorm with turbulence is an abnormal meteorological phenomenon with frequent change that cannot be monitored perfectly just as some patient with unstable condition and that cannot be ascertained about not only the possibility of its happening but also the degree of how big the accident is. Yet the use of jet current which has the possibility of CAT can be an act of high social utility where we not only drastically cut down on time fuel also guarantee the arrival and departure on schedule when landing in airports that have thunderstorm which does not appear as fatal risk. Although we could take some measures where we can predict and avoid the potential risk, easing the regular duty of care is necessary by applying the legal principles of permitted risk concerning the incidents and accidents caused by operating in areas with the risk of turbulence or CAT with the low probability by the reason of social utility.

• Geomechanics and Engineering
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• v.8 no.1
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• pp.81-95
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• 2015

The permeability behavior of Ariake clays has been investigated by constant rate of strain (CRS) consolidation tests with vertical or radial drainage. Three types of Ariake clays, namely undisturbed Ariake clay samples from the Saga plain, Japan (aged Ariake clay), clay deposit in shallow seabed of the Ariake Sea (young Ariake clay) and reconstituted Ariake clay samples using the soil sampled from the Saga plain, were tested. The test results indicate that the deduced permeability in the horizontal direction ($k_h$) is generally larger than that in the vertical direction ($k_v$). Under odometer condition, the permeability ratio ($k_h/k_v$) increases with the vertical strain. It is also found that the development of the permeability anisotropy is influenced by the inter-particle bonds and clay content of the sample. The aged Ariake clay has stronger initial inter-particle bonds than the young and reconstituted Ariake clays, resulting in slower increase of $k_h/k_v$ with the vertical strain. The young Ariake clay has higher clay content than the reconstituted Ariake clay, resulting in higher values of $k_h/k_v$. The microstructure of the samples before and after the consolidation test has been examined qualitatively by scanning electron microscopy (SEM) image and semi-quantitatively by mercury intrusion porosimetry (MIP) tests. The SEM images indicate that there are more cut edges of platy clay particles on a vertical plane (with respect to the deposition direction) and there are more faces of platy clay particles on a horizontal plane. This tendency increases with the increase of one-dimensional (1D) deformation. MIP test results show that using a sample with a larger vertical surface area has a larger cumulative intruded pore volume, i.e., mercury can be intruded into the sample more easily from the horizontal direction (vertical plane) under the same pressure. Therefore, the permeability anisotropy of Ariake clays is the result of the anisotropic microstructure of the clay samples.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.254-260
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• 1999

Meteor Burst Communication can provide effective and economical means of communication where long distance VHF NLOS data transmission is needed; often ranges more than 1000 km. It has been, however, so far considered unsuitable for short distance application because of phenomenal decrease in burst durations, which leads to decreation of total duty rate of the system. This paper extensively analyzes characteristics of shot distance MB(Meteor Burst) path and shows the low duty rate may be improved by increasing burst rate through adapting antenna beam width to cover entire hot-spot region in the space and, by compensating effective burst length through cutting down man-made noises introduced by antenna. Based on the analysis, we are developed a small-opening-cavity antenna, especially designed for short distance MB path. In operation, the antenna is to be buried under ground surface so as to improve directivity and reduces noise introduction. The antenna exhibits power gain of 3 dB with 90 degree beam width and thus enables to illuminate entire hot-spot regions with the elevation angle of 8-90 degree which is the case of transmission less than 100 km. Directivity horizontal to earth surface is suppressed to minimum which enables to cut man-made noises from near-by sources down to more than 3 dB from the level reported with conventional 4 element Yagi. A series of experiments performed on 100 km MB paths have conformed that, with the antenna installed at receiving site, the burst rate and duration time have been noticed to increase by 10 and 20 percent respectively from the values obtained by conventional 4-element Yagi antenna under same testing condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.788-801
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• 1998

Meteor Burst Communication can provide effective and economical means of communication where long distance VHF NLOS data transmission is needed ; often ranges more than 1000 km. It has been, however, so far considered unsuitable for short distance application because of phenomenal decrease in burst durations, which leads to decreation of total duty rate of the system. This paper extensively analyzes characteristics of shot distance MB(Meteor Burst) path and shows the low duty rate may be improved by increasing burst rate through adapting antennal beam width to cover entire hot-spot region in the space and, by compensating effective burst length throughcutting down man-made noises introduced by antennal. Based on the analysis, we are developed a small-opening-cavity antennal, especially designed for short distance MB path. In operation, the antenna is to be buried under ground surface so as to improve directivity and reduces noise introduction. The antennal exhibits power gain of 3 dB with 90 degree beam width and thus enables to illuminate entire hot-spot regions with the elevation angle of 8-90 degree which is the case of transmission less than 100 km. Directivity horizontal to earth surface is suppressed to minimum which enables to cut man-made noises from near-by sources down to more than 3 dB from the level reported with conventional 4 element Yagi. A series of experiments performed on 100km MB paths have conformed that, with the antenna installed at receiving site, the burst rate and duration time have been noticed to increase by 10 and 20 percent respectively from the values obtained by conventional 4-element Yagi antennal under same testing condition.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.137-150
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• 2002

Recently, plane failure mode occurred frequently along the bedding plane having low angle dip about 20 degree when cutting slopes were constructed in sedimentary rock region of the Gyeongsang Basin. Landslide of the Whangryeong Mountain which was occurred at Busan Metropolitan City in 1999 belongs to the category mentioned above. Reconstruction for cutting slope of the Whangryeong Mountain has finished in 2000 and final grade of reconstructed cutting slope is 1:2.0. To analyze slope failure mode for landslide of the Whangryeong Mountain, various analyses were performed such as in-situ investigation and test, drilling, laboratory test, aerial photograph interpretation, X-ray diffraction analysis, and slope stability analysis using Stereographic Projection and Limit Equilibrium methods. As the result, it is identified that tension cracks had been developed one year before the landslide took place. The tension crack semis to be formed by merging several joint sets. It appears that failure blocks broke down along the sliding planes of different layers. Risk of plane failure is conformed as a result of stability analysis using Stereographic Projection and Limit Equilibrium methods in case that greenish gray tuffaceous shales, regared as sliding planes, are weathered. From now on, a detailed investigation is needed for the thin layers which is sensitive to weathering, and stability analysis for this layer is performed at cut slope construction site having similar geological condition.

• Polymer(Korea)
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• v.35 no.3
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• pp.203-209
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• 2011

Two smooth and textured surfaced HDPE geomembranes (GMs) were cut into dumbbell shape and notched where depth of the notch produced a ligament thickness of 10% to 90% of the nominal thickness with the specimen at 10% interval. A series of laboratory simulation test for installation damage were carried out at different loading cycles on HDPE GMs in accordance with ISO 10722 test method and the effect of number of loading cycle on installation damage was compared. It was found that yield stress and elongation at yield point decreased gradually as the notch depth was increased. Both installation damaged and notched, GMs were used to understand stress crack behavior and this behavior was observed through NCTL test at $50{\pm}1^{\circ}C$ at different yield stresses immerging in pH 4 and pH 12 buffer solutions. Over 35% tensile load, GMs became vulnerable to stress cracking. Both damaged and notched GMs showed the same trend. Especially, notched GMs showed less strength than installation damaged GMs at every stress cracking test condition.

• Journal of Korean Society of Forest Science
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• v.70 no.1
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• pp.1-6
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• 1985

The purpose of this experiment lies in finding the most appropriate cutting condition of Taxus cuspidata Sieb. et Zucc. which has been considered valuable tree species in gardening. Statistical analysis was focused on the comparison of the average ratios of rooting between greenhouses and fields, based on the observation rooted autogenis. To conduct this survey, hardwood cutting of Taxus cuspidata Sieb. et Zucc. were performed at both places of experiment above on April 20, 1982 with rooting results calculated on October 31, 1982. After formation of cuttings, it was soaked in IBA 200 ppm for 12 hours and than put in a bed. A summary of the result is presented as follows; 1) Cutting at the greenhouse showed higher average rate of rooting than at fields. Same tendency was found regardless of the differences in treatment. 2) It was clear that IBA-treatment contributed remarkably to causing higher average rooting rate. As an evidence, when twenty centimeter cuttings were inserted sandy media, IBA-treated area resulted in eighty six percent of average rooting rate, as compared with only twenty three percent in nontreatment case. In case of field cutting, IBA-treatment brought about fifty three percent of rooting in comparison with eleven percent nontreatment. 3) When sandy soil, loam and brown soil were separately used as cutting media, the highest rooting rate was found in case of sandy soil, without any difference between the two experimental places above. 4) As a result of the analysis to seek the impact of the length of cuttings on rooting, the range of length form fifteen to twenty centimeter was apparently most appropriate. It was also found that the rate of rooting declined beyond twenty five centimeter. 5) Two kinds of rooting pattern were observed. One was the case that callus cell lump was created on the lower cut side of cuttings. Importantly, root radical were formed inside the lump to influence the germination of root system. The other relates to the case that adventitious root which look like lateral roots appeared at the stem region. In abstract, first, sandy soil was effectively recommended in case of hardwood cutting in April. Second, the most appropriate length of cuttings ranged between fifteen and twenty centimeters. Third, high density IBA treatment was clearly effective. Forth, for proper environmental management, both pre-disinfection of sail by sterilizer and maintenance of high relative humidity were essentially required.

• Journal of Sericultural and Entomological Science
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• no.11
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• pp.31-44
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• 1970

This experiment is conducted fer method cf bring to perfectly from defective cutting sapling 25 a production method of sapling which is to substitute for conventional graf ting. 1. In green wood cutting root comes out after 15 days of cutting with nearly straight development of root system; after 40 days of cutting, roots with total length of 1119 mms 43 roots, and 5.4 grs a root in total weight obtained. 2. Survival percentage of green wood cutting ranges between 56％ and 90％, average 73％ of that and it varies with natural characteristics of varietes. The results show variety of Gaeryang-Suban and Iljiroe with 80％ as a best ones in contrast with the variety of Shipyung. 3. The varietics or Gaeryang-Suban. Iljiroe, Suwon-Sang No.4, Rosang makes of much more roots than Yongchonchuwoo and Shipyung do. 4. Root ability made good number of roots commercially, when cutting is conducted soaking in 0.01 ％ NAA solution or 0.02％ NAA solution for 2 or 3 seconds as a chemical promoter. 5. Economical measures for increase of scion adapted 1) 2 scions from a green wood 50 cm long should be taken and basal pan of scion at its middle portion should be cut right under the node. 2) Scions below 50cm long may be used. Small scions or growthceased shoots h3ve also considerable root ability enough to be used. 3) Thus far, up 100,000 scions might be produced in 10 a. 6. We can find number of root increased, when cutting the opposite side in obliquity manner at 450. 7. When 110,000 saplings in 10 a. for the production of bring to perfectly from defective cutting sapling planted, quality of stocks does not go to bad condition without any obstacles in practical use. 8. Although the times or grafting delayed until middle of July, quality of sapling goes just a little down. Grafting may be conducted from early June to middle of July separately in several times, and the green wood of prunned mulberry in spring is available for a scion after end of June. 9. 10 grs weight of defective cutting sapling makes 95％ of complete sapling, otherwise 5 or 10 grs in weight of one becomes 80％ of complete sapling with its quality as similar as grafted one. 10. When the sapling planted, its branches should be cut, leaving 3 or 4 buds at the bottom of new branches. 11. In view of economical stand point, production cost of bring to perfectly from defective cutting sapling obtains 52％ of grafting cost.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.119-133
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• 2020

Underground utility tunnel, the most representative cut and cover structure, is subjected to seismic force by displacement of the surrounding soil. In 2020, Korea Infrastructure Safety Corporation has published "Seismic Performance Evaluation Guideline for Existing Utility Tunnel." This paper introduces two seismic evaluation methods, RDM (Response Displacement Method) and RHA (Response History Analysis) adopted in the guide and compares the methods for an example of an existing utility tunnel. The test tunnel had been constructed in 1988 and seismic design was not considered. RDM is performed by single and double cosine methods based on the velocity response spectrum at the base rock. RHA is performed by finite difference analysis that is able to consider nonlinear behavior of soil and structure together in two-dimensional plane strain condition. The utility tunnel shows elastic behavior for RDM, but shows plastic hinge for RHA under the collapse prevention level earthquake.

• Korean journal of applied entomology
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• v.43 no.2
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• pp.135-141
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• 2004

This study was carried out to review the distributional data of Dorcus hopei in Korea and to investigate ecological characteristics to develop a mass rearing technique of the species. The coupling period of the male and female was needed at least 2 weeks in condition of 6 months after emergence, and the optimal sex ratio for oviposition was 2♀：1♂. Eggs were laid singly, up to 27.3 per female. The pre-ovipostion period was average 147.3 days, egg-period was 15.6 days on the average, and oviposition period was at least 120 days. The optimum size of oviposition room was 55${\times}$40${\times}$35 cm with 3-4 oviposition-trees cut in size of 15${\times}$15 cm. Quercus acutissima was highly preferred for the oviposition. Developing period of each instar in the insectary (25$^{\circ}C$, 75％ R.H.. 16L：8D) was 24.1 days for the 1st instar,29.8 days for the 2nd, and 131.2 days for the 3rd instar, and 28.9 days for the pupa. The longevity of adults was longer than 35 months. The period of induced dormancy was needed at least 3-4 months.