• Radiation Oncology Journal
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• v.19 no.3
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• pp.259-264
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• 2001

Purpose : We investigated the temporal alterations of apoptosis and mitotic death following irradiation in the rat's small intestinal crypts. Materials and methods : Male Sprague-Dawley rats were irradiated 2 Gy by 6 MV linear accelerator and sacrified at 2, 4, 8, 24, 48 hours after irradiation. The mean numbers of the apoptotic cells and mitotic cells per their small intestinal crypts were measured in the unirradiated control and irradiated groups. To compare with H & E staining, ISEL (In Situ End Labelling) were peformed in the group having the highest apoptotic count. Results : The mean number of the apoptosis per crypt in the control group was 0.14 and those at 2, 4, 8, 24, 48 hours after irradiation were 1.43, 3.19, 1.15, 0.26, 0.17, respectively. So the apoptosis development was increased upto 4 hours and then normalized around 24 hours following irradiation. The mean number of the mitotic cells per crypt in the control group was 1.29 and those at 2, 4, 8, 24, 48 hours after irradiation were 0.56, 0.47, 0.23, 0.65, 1.19, respectively. The mitotic cell counts following irradiation was decreased to 8 hours and recovered to the normal level about 48 hours. So the increment of apoptotic cell count was occurred earlier and more remarkable than the decrement of mitotic cell count after irradiation. According to the staining time, false positivity was found in the ISEL staining. Conclusions : The cell death in the small intestinal crypt developed by acute radiation damage was usually decreased to the normal level within $24\~48\;hours$ after irradiation and the apoptosis was thought to be more important process than the mitotic death.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.726-736
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• 2012

This paper deals with Spin/Stall Recovery Parachute System from design to ground taxiing stage which would be deployed on the high speed taxi of turbo-prop airplane. In detail design phase, design parameters- riser length, parachute type, size, porosity, parachute canopy filling time, and deployment method- were considered based on the analytical disciplines such as aerodynamics, structures, and stability & control. Before the installation of Spin/Stall Recovery System of turbo-prop airplane, all control functions of this system were validated by the SBTB(System Breakout Test Box) in the laboratory. SBTB was used to confirm if it can detect faults, and simulate the firing of pyrotechnic devices that control the deployment and jettison of it. Once confirmed normal operation, deployment of parachute on the high speed taxiing were performed.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.541-545
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• 2010

식생이 소실된 산불 피해 지역에서 유실되는 토양의 식생회복에 따른 정량적인 변화를 파악하고, 사면토양과 유실토양의 성분분석을 수행하여 이화학적 특성을 파악하고자 한다. 산불 이후 10개의 조사구에서 강우에 의해 유실토양의 양을 측정한 후 토양을 건조시켜 보관하였다. 토양의 입도분석, 유기물함량, 건조밀도 등을 조사하였다. 그리고 전처리한 토양수는 ICP를 이용하여 Fe, Mn, P, Al, Zn, Na, Mg, K, Ca의 성분분석을 수행하였다. 산불 이후 시간경과에 따른 조사구별 식생 회복은 빠른 지역과 느린 지역으로 크게 구분한다. 재생이 불량한 지역은 재생이 왕성한 지역에 비해 상대적으로 많은 양의 토양이 유실되었다. 사면토양의 성분분석 결과 재생불량 지역의 성분함량이 가장 작았으며, 재생왕성 지역은 비피해지에 비해 성분함량이 대체로 높았다. 유실토양의 성분분석 결과 식생회복이 느린 조사구에서 영양염류 함량이 대체로 낮았다. 그러나 식생회복이 느린 조사구에서 많은 양의 토양이 유실되기 때문에 정량적인 영양염류의 소실량은 가장 많았다. 따라서 지표식생이 없는 지역은 다량의 토양유실로 인해 다량의 영양염류가 소실되어 식생 재생을 더디게 만드는 것으로 판단된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.333-333
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• 2010

크라이오 펌프는 크기에 비해 상대적으로 큰 배기속도를 가지고 있고 자체 기체 방출이 적어 비교적 쉽고 빠르게 도달압력을 낮출 수 있다. 또 초고진공 펌프로서 경쟁 상대인 터보분자 펌프보다 기체 돌입에 대한 기계적 사고 가능성이 낮다. 그러나 흡착 패널의 온도에 민감하게 반응하는 배기 성능 측면에서 볼 때 크라이오 펌프의 대유량 및 펄스 기체 부하에 대한 성능 유지 및 회복능력은 의문의 여지가 있다. 크라이오 펌프의 기체부하에 대한 공식적인 성능지표로는 최대배기량(max. throughput)과 교차(crossover)값이 있다. 전자는 연속적인 유량[$Pa{\cdot}m^3/s$]에 대해, 또 후자는 일정 기체량[$Pa{\cdot}m^3$]에 대해 흡착 패널이 20 K를 넘지 않는 가동범위를 구하는 것이다. 교차값은 넓은 의미에서 펄스 기체부하에 대한 성능으로 볼 수도 있지만 원래 목적은 진공용기를 저진공 상태에서 고진공 상태로 전환하는 시점을 정하려는 데 있다. 펌프회사에서 제공하는 사양에는 대부분 아르곤 회복시간(Ar recovery time)이라는 지표가 있는데 이는 아르곤을 상당한 유량으로 흘리다 멈췄을 때 얼마나 빨리 기저 상태로 회복되는가를 나타낸다. 보통 사양서에 제시하지는 않지만 주로 크라이오 펌프의 재생상태를 알아보기 위해 사용하는 걸프(gulp) 시험이 있는데 일정량의 기체를 펄스로 도입한 후 압력변화를 기록하여 재생후 배기성능 회복 능력을 보는 것이다. 이들은 겉보기에 서로 다르지만 한편으로는 서로 중복되거나 연관성을 가지고 있어서 실용적인 면에서 절차들을 비교, 검토 및 개선하고 때에 따라서는 적절히 결합할 수 있는 방안을 모색할 필요성이 있다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.216-224
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• 1999

In the paper we propose two recovery methods by adopting a rollback and/or roll-forward technique (S) to recover TMR failures in a TMR (structured ) system that is the simplest spatial redundancy. This technique is apparently effective to recovering TMR failures primarily caused by transient faults. The proposed policies carry out few reconfigurations at the cost of (minimal) time-overhead needed for those time-redundant schemes. The optimal checkpoint-interval vectors are derived for both methods through the likelihoods of all (possible) states of the system as well as the total execution-time. Consequently the effectiveness of our proposed policies is validated through certain numerical examples and simulations.

• Composites Research
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• v.17 no.3
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• pp.8-14
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• 2004

The effect of moisture absorption on the mechanical properties in carbon fiber reinforced composites has been investigated with various moisture environment such as sea water, tap water and distilled water. It also has been studied about the influence of drying of the immersed specimen for a certain period of time on the mechanical properties. As a result, we found that the ratio of moisture absorption mainly depended on the immersion time in the moisture environment and that of the immersed specimen for a certain period of time decreased with the drying time. We also found that tensile strength decreased with the increasing of the ratio of moisture absorption and the tensile strength decreased by moisture absorption recovered up to some extent by drying the specimen.

• Radiation Oncology Journal
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• v.14 no.4
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• pp.255-264
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• 1996

Purpose : Paclitaxel is a chemotherapeutic agent with potent microtubule stabilizing activity that arrests cell cycle in $G_2$-M Because $G_2$-M is the most radiosensitive Phase of the cell cycle, paclitaxel has potential as a cell cycle- specific radiosensitizer. This study was designed to investigate the ability of paclitaxel to increase the radiotoxicity in normal small bowel mucosa of the rat. materials and Methods : A sigle intraperitoneal infusion of paclitaxel (10mg/kg), and a single irradiation(8 Gy, x-ray) to the whole abdomen and combination of radiation(8 Gr, x-ray) 24 hours after paclitaxel infusion in the rats were done. The changes of jejunal mucosa, and kinetics of mitotic arrest and apoptosis in the jejunal crypt were defined at 6 hours - 5 days after each treatment histologically. Results : Paclitaxel blocked jejunal crypt cell in mitosis and induced minmal apoptosis. Mitotic arrest by paclitaxel was peaked at 6 hours after infusion and returned to normal by 24 hours. Radiation induced apoptosis and peaked at 6 hours and returned to normal by 24 hours. Combination of paclitaxel and radiation blocked crypt cell in mitosis at 3 days and induced apoptosis slightly at 6 hours and 24 hours and returned to normal by 3 days. The incidence of apoptosis in combined group at 6 hours was slightly higher than normal control but significantly lower than radiation alone group. The major changes of jejunal mucosa were nuclear vesicle and atypia which were appeared at 6 hours - 3 days and returned to normal by 5 days The degree of the mucosal changes are not different in 3 groups except for absence of inflmmatory reaction in radiation group. Conclusion : Mitotic arrest by paclitaxel was peaked at 6 hours and returned to normal by 24 hours and paclitaxel induced minimal apoptosis. Radiation induced apoptosis, peaked at 6 hours and returned to normal by 24 hours. Radiation-induced apoptosis was less in combined group which suggested that paclitaxel have a radioprotective effect when radiation was given 24 hours after paclitaxel infusion.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.313-315
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• 2000

본 논문에서는 프랜트 설계 단계에서 안정도 해석을 행함에 있어 부하모델의 차이가 안정도 해석 결과에 미치는 영향을 비교 평가하였다. 플랜트 부하의 대부분인 유도전동기 모델을 달리 적용함에 따라 안정도 해석 시 최대 허용 고장제거시간이 매우 다르게 나타난다는 것을 보여 주었다. 또한 유도전동기의 모델 표현을 달리함에 따라 고장제거 후 모선의 전압회복 특성과 전동기 속도 회복 특성이 매우 달라짐을 보여 주면서 산업플랜트 보호계전 시스템 설계를 위한 안정도 해석 시 유도전동기 모델 적용방법에 있어 유의하여 할 사항을 제시하였다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.377-378
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• 2001

양식과정중 마취는 어류를 고정시키거나, 인공 채란, 종묘 입식, 출하시 수송 및 선별과 같은 일상적인 취급에서 스트레스를 감소시키기 위한 방안으로 많이 이용되어 왔다(Westernized, 1993). MS-222는 어류에 사용되는 가장 일반적인 마취제로 물에 잘 녹는 하얀 결정상의 가루로 빠른 마취를 일으키고 회복시간은 짧다(Bourne, 1984). 그러나 일반 어류 양식장에서 널리 사용되기에는 가격이 비교적 비싼 편이다. (중략)

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.767-772
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• 2011

The purpose of this study was to find out required time for recovery of nutritional disorder by Fe-DTPA treatment in induced Fe-deficient tomato cultivars and to select stable Fe-chelate in high pH of nutrient solution. The pH levels of nutrient solution were amended with 6.0, 7.0, and 8.0. Then Fe-EDTA (Ethylenediaminetetraacetic acid, ferric-sodium salt), Fe-DTPA (Sodium ferric diethylenetriamine pentaacetate), and Fe-EDDHA (Ethylenediamine-N,N-bis (2-hydroxyphenylacetic acid) ferric-sodium salt)) were treated as Fe $2.0mg\;L^{-1}$ concentration. The Fe-DTPA and Fe-EDDHA were stable in the nutrient solution of pH 6.0~8.0 but Fe-EDTA in nutrient solution of pH 8.0 was to become insoluble by 25%. The Fe $2.0mg\;L^{-1}$ as Fe-DTPA was treated for recovery of Fe deficient tomato seedlings. In case of Redyoyo and Supersunroad cultivars, total chlorophyll and Fe contents of leaves were recovered as much as those of normal leaves in 5 days. The Rafito cultivar for complete recovery was taken 7 days. When Fe $2.0mg\;L^{-1}$ as Fe-DTPA was supplied to Fe-deficient tomato seedlings, in geotype, heme oxigenase recovered as much as normal leaves in 24 hours in the Rafito and Redyoyo. However, it was not remarkable difference by elapsed time in the Supersunroad.