• 한국전자파학회논문지
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• 제19권9호
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• pp.947-956
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• 2008

본 논문에서는 고출력 전자기파 발생 장치에 사용될 소형화 된 원뿔 계단형 COBRA(Coaxial Beam-Rotating Antenna)를 제안하였다. COBRA는 혼 안테나와 렌즈로 구성되는데, 일반적인 방법으로 설계할 경우 정전 파괴 방지를 위해 그 크기가 매우 커지게 된다. 소형화를 위해 안테나의 길이만 줄일 경우 위상 오류의 증가로 인해 안테나의 이득이 줄어들게 되는데, 이를 방지하기 위해 COBRA 렌즈를 원뿔 계단형으로 변형시켜 개구면에서의 위상 오류가 보정 되도록 하였다. 시뮬레이션 결과, 1,300 mm 길이의 안테나를 600 mm로 줄였음에도 불구하고 제안된 안테나는 더 높은 이득을 보였으며, 제작하고 측정된 원뿔 계단형 COBRA의 이득은 26.2 dBi로 나타났다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.75-81
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• 1996

COBRA-TF is a two fluid, three field subchannel code. Three fields are continuous vapor, continuous liquid and droplet. Some assessments are conducted to validate the related models and to estimate a code ability through dryout and post-CHF experiment in a tube and DNB test in rod bundles. It turned out form dryout and post-CHF experiment that the predicted dryout locations and wall temperature profiles are in close agreement with the experiments. On the other hand, DNB prediction of COBRA-TF are performed for two kinds of rod bundles along with EPRI CHF correlation. To estimate its performance COBRA-IV of homogeneous model is also run for the same data. The results say that COBRA-TF/EPRI is better in DNB prediction than COBRA-IV/EPRI. In addition the thermal-hydraulic behaviors due to the different two-phase flow models are presented at the condition of CHF.

• 한국국방경영분석학회지
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• 제36권3호
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• pp.83-93
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• 2010

본 논문에서는 훈련용 워게임모델의 근접전투 피해평가를 위한 새로운 근접전투전문가시스템을 제안하였다. 군에서 사용하고 있는 워게임모델에서 피해평가 모의논리는 아주 중요한 모의가능이다. 현재, 육군의 군사단급 워게임모델인 창조21 모델에서는 근접전투 피해평가의 핵심기능이 창조21 모델에서 계산되지 않고, 공개소스와 내부논리를 알 수 없는 미군에서 제작한 근접전투전문가시스템(일명 COBRA)에서 별도로 계산되고, 이 결과가 네트워크를 통해 창조21 모델로 전송되어 근접전투에 대한 피해평가가 이루어진다. 본 논문에서는 COBRA를 대체할 수 있는 근접전투전문가시스템을 의사결정나무를 이용해서 제안하였다. 제안하는 시스템은 실험결과 COBRA와 유사한 성능을 보였고, 시스템의 계산량이 적었고 군사작전 상황에 적합하였다.

• Nuclear Engineering and Technology
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• 제30권3호
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• pp.181-193
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• 1998

The COBRA-TF liquid droplet entrainment models have been assessed and improved through various experiments. The COBRA-TF code uses the Wurtz entrainment model in the film mist flow regime and the mechanistic model based on the critical Weber number and critical vapor velocity in the hot wall flow regimes, respectively. The Wurtz model has been replaced with the modified Sugawara model. The assessment against the experiments by Hewitt, Keeys, Yanai, and Whalley showed the modified Sugawara model better predicts the steam-water as well as the air-water experiments for the film mist flow regime. For hot wall flow regime, the COBRA-TF entrainment model was modified using two methods, one with an increased critical Weber number and the other with the Yonomoto's critical vapor velocity model. The modified models were assessed using the FLECHT-SEASET bottom reflood tests. The results showed that the Yonomoto model best predicts the quenching time, whereas the local maximum rod temperature was not affected much.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.591-598
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• 1997

The COBRA/RELAPS code, an integrated version of the COBRA-TF and RELAP5/MOD3 codes, has been developed for the realistic simulations of complicated, multi-dimensional, two-phase, thermal-hydraulic system transients in light water reactors. Recently, KAERA developed an unified version of the COBRA/RELAP5 code, which can run in serial mode on both workstations and personal computers. This paper provides the brief overview of the code integration scheme, the recent code modifications, the developmental assessments, and the future development plan.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.147.1-147
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• 2001

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 추계학술발표회요약집
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• pp.126-126
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• 1998

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.158.1-158
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• 2002

• Journal of Animal Science and Technology
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• 제59권9호
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• pp.20.1-20.9
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• 2017

Background: Ribonuclease (RNase) is one of the few toxic proteins that are present constantly in snake venoms of all types. However, to date this RNase is still poorly studied in comparison not only with other toxic proteins of snake venom, but also with the enzymes of RNase group. The objective of this paper was to investigate some properties of RNase from venom of Vietnam cobra Naja atra. Methods: Kinetic methods and gel filtration chromatography were used to investigate RNase from venom of Vietnam cobra. Results: RNase from venom of Vietnam cobra Naja atra has some characteristic properties. This RNase is a thermostable enzyme and has high conformational stability. This is the only acidic enzyme of the RNase A superfamily exhibiting a high catalytic activity in the pH range of 1-4, with $pH_{opt}=2.58{\pm}0.35$. Its activity is considerably reduced with increasing ionic strength of reaction mixture. Venom proteins are separated by gel filtration into four peaks with ribonucleolytic activity, which is abnormally distributed among the isoforms: only a small part of the RNase activity is present in fractions of proteins with molecular weights of 12-15 kDa and more than 30 kDa, but most of the enzyme activity is detected in fractions of polypeptides, having molecular weights of less than 9 kDa, that is unexpected. Conclusions: RNase from the venom of Vietnam cobra is a unique member of RNase A superfamily according to its acidic optimum pH ($pH_{opt}=2.58{\pm}0.35$) and extremely low molecular weights of its major isoforms (approximately 8.95 kDa for RNase III and 5.93 kDa for RNase IV).

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.284-289
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• 1996

The predictions of the COBRA-IV-I code with the modified turbulent mixing and void drift models have been compared with the diabatic two-phase flow data on equilibrium quality. The turbulent mixing model based on an equal mass exchange of the existing COBRA-IV-I code has been modified to that based on an equal volume exchange between adjacent subchannels, and a void drift model has been newly incorporated in the code. To evaluate the performance of the equal volume exchange turbulent mixing model and the effects of the void drift model, the diabatic steam-water two-phase flow data obtained for the 9-rod bundle test under the typical operating conditions of the boiling water reactor(BWR) conducted by the General Electric (GE) were analyzed by the modified COBRA-IV-I code. The analysis indicates that the equal volume exchange turbulent mixing model with void drift predicts the observed two-phase flow data trends better than the equal mass exchange model, and to predict the correct data trends a more physically based void drift model need to be developed.