• 대한영상의학회지
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• 제85권2호
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• pp.394-408
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• 2024

목적 CT 영상 소견을 이용하여 편평세포폐암에서 programmed death ligand 1 (이하 PD-L1)의 발현을 예측하는 모델을 구축해 보고자 하였다. 대상과 방법 PD-L1 발현검사 결과를 포함하고 있는 97명의 편평세포폐암 환자를 포함하였고 종양 치료 전 시행한 CT 영상 소견을 분석하였다. 전체 환자군과 40명의 진행성(≥ stage IIIB) 병기 환자군에 대하여 PD-L1 발현 예측을 위한 다중 로지스틱 회귀 분석 모델 구축을 시행하였다. 각각의 환자군에 대하여 곡선 아래 면적(areas under the receiver operating characteristic curves; 이하 AUCs)을 분석하여 예측력을 평가하였다. 결과 전체 환자군에서 '전체 유의인자 모델'(종양병기, 종양크기, 흉막결절, 폐전이)의 AUC 값은 0.652이며, '선택 유의인자 모델'(흉막결절)은 0.556이었다. 진행성 병기 환자군에서 '선택 유의인자 모델'(종양크기, 흉막결절, 폐소수전이, 간질성폐렴의 부재)의 AUC 값은 0.897이었다. 이러한 인자들 중 흉막결절과 폐소수전이는 높은 오즈비를 보였다(각각, 8.78과 16.35). 결론 본 연구에서의 모델은 편평세포폐암의 PD-L1 발현예측의 가능성을 보여주었으며 흉막결절과 폐소수전이는 PD-L1 발현을 예측하는데 중요한 CT 예측인자였다.

• 한국인쇄학회지
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• 제25권1호
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• pp.53-64
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• 2007

Gravure printing is the most useful printing process than any other engraving printing method. According to the cell which is variable size and depth, ink is transferred substrates. So, the amount of ink from cells has a great effect on the qualities of final printed products. The variables effect on the printability of final products are proportion of the width and length, the rhelogical properties, roll speed etc. However the mechanism of gravure is difficult to study scientifically because of high speed and excessively small size of the cell. To approach the mechanism we experimented the real test by using gravure printability. The condition of variables of IGT is pressure and velocity. By using Polyflow 3. 10. 0 simulation software, we built up the theoretical model under the constant variables. Then, we compared the real test with the simulation results. Therefore, it is studied the mechanism of gravure scientifically and it can be analysed the effect of the variable conditions.

• 전력전자학회논문지
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• 제18권1호
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• pp.45-53
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• 2013

Fuel cell power system is one of the most promising energy source for the alternative energy because it has unique advantages such as high energy density, no power drop during operation, and feasible to make compact size. However, due to very low response time, fuel cell is difficult to correspond to drastic load changes and start-up operation. For solving these problem, fuel cell power system must include energy storage device such as Li-Poly battery or super capacitor. Therefore, bi-directional DC-DC converter must be required for this storage device and fuel cell-PCS control. This paper presents a design and modeling of the bi-directional DC/DC converter. Firstly, we present modeling the boost and buck mode of the bi-directional converter through both PWM switch model and state space averaging technique. Secondly, in order to minimize output ripple and transient response overshoot, we have two identical DC-DC converters interleaved and adopt two-loop voltage-current controller. The proposed bi-directional DC-DC converter's modeling method and control design have been verified with computer simulation and experimentation.

• Preventive Nutrition and Food Science
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• 제15권4호
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• pp.255-261
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• 2010

Ischemic stroke, a major cause of death and disability worldwide, is caused by occlusion of cerebral arteries that, coupled with or without reperfusion, results in prolonged ischemia (hypoxia and hypoglycemia) and, ultimately, brain damage. In this study, we examined whether methanol extract of the whole plant of Cassia mimosoides var. nomame Makino that grows naturally in Korea, as well as Japan and China, and some of its fractions obtained by partitioning with organic solvents could protect human hepatocellular carcinoma cells (HepG2) under hypoxic condition by inhibiting apoptosis. We also investigated if these extracts could attenuate brain damage in a rat model of 2 hr of ischemia, generated by middle cerebral artery occlusion, and 22 hr of reperfusion. The whole extract ($100{\mu}g$/mL) maintained the cell number at more than half of that initially plated, even after 24 hr of cell culture under hypoxic condition (3% $O_2$). In the absence of the whole extract, almost all of the cells were dead by this time point. This improvement of cell viability came from a delay of apoptosis, which was confirmed by observing the timing of the formation of a DNA ladder when assessed by gel electrophoresis. Of fractions soluble in hexane, ethyl acetate (EA), butanol and water, EA extracts were selected for the animal experiments, as they improved cell viability at the lowest concentration ($10{\mu}g$/mL). The whole extract (200 mg/kg) and EA extract (10 and 20 mg/kg) significantly reduced infarct size, a measure of brain damage, by 34.7, 33.8 and 45.2.0%, respectively, when assessed by 2,3,5-triphenyl tetrazolium chloride staining. The results suggest that intake of Cassia mimosoides var. nomame Makino might be beneficial for preventing ischemic stroke through inhibition of brain cell apoptosis.

• IMMUNE NETWORK
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• 제10권1호
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• pp.15-25
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• 2010

Background: Rat mast cells were regarded as a good model for mast cell function in immune response. Methods: Rat bone marrow mast cells (BMMC) were prepared both by recombinant rat IL-3 (rrIL-3) and by recombinant mouse stem cell factor (rmSCF), and investigated for both proliferation and differentiation in time course. Rat BMMC was induced by culture of rat bone marrow cells (BMCs) in the presence of both rrIL-3 (5 ng/ml) and rmSCF (5 ng/ml). Culture media were changed 2 times per week with the cell number condition of $5{\times}10^4/ml$ in 6 well plate. Proliferation was analyzed by cell number and cell counting kit-8 (CCK-8) and differentiation was by rat mast cell protease (RMCP) II and histamine. Results: Cell proliferation rates reached a maximum at 8 or 11 days of culture and decreased thereafter. However, both RMCP II production and histamine synthesis peaked after 11 days of culture. By real time RT-PCR, the level of histidine decarboxylase mRNA was more than 500 times higher on culture day 11 than on culture day 5. By transmission electron microscopy, the cells were heterogeneous in size and contained cytoplasmic granules. Using gated flow cytometry, we showed that cultured BMCs expressed high levels of $Fc{\varepsilon}RI$ and the mast cell antigen, ganglioside, on culture day 11. Conclusion: These results indicate that rat BMMCs were generated by culturing BMCs in the presence of rrII-3 and rmSCF and that the BMMCs have the characteristics of mucosal mast cells.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.169-172
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• 2015

This paper presents a numerical investigation on kerosene-air mixture detonation and behaviors of thermal elasto-plstic thin metal tube under detonation loading based on multi-material analysis. The detonation loading is modeled by the kerosene-air mixture detonation which is compared with CJ condition and experimental cell size. And the thermal softening effect on elasto-plstic model of metal tube is indicated by different dynamic response of detonation loaded tube in various temperature and tube thickness.

• 대한기계학회논문집A
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• 제35권7호
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• pp.745-751
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• 2011

입자강화 알루미늄 복합재의 강도를 계산하기 위하여 압밀 후 냉각할 때 일어나는 전위 펀칭을 유한요소로 모델링 하였다. 다양한 입자의 체적비에서 입자의 크기가 강도에 미치는 영향을 고려하기 위하여 강화 입자 주위에 변형률 구배 소성과 테일러 전위 모델을 적용하였다. 변형률 구배는, 구형 단위 셀이 냉각하는 동안 입자와 기지재의 열팽창계수 차이에 의한 전위 펀칭이 일어날 때 형성되는 등가소성변형률로부터 구하였다. 펀칭된 영역에 걸쳐 평균적으로 변형률 구배를 고려함으로써 항복 응력이 증가하는 것을 관찰하였다. 유한요소 해석을 활용하여 다양한 입자 크기와 체적비에 대하여 SiC 강화 알루미늄 356-T6 복합재의 축대칭 단위 셀의 인장시 강도의 변화를 예측하였다. 예측된 강도는 실험 데이터와 잘 일치하며, 입자 크기 의존 효과를 분명히 보인다.

• 한국측량학회지
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• 제16권1호
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• pp.67-74
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• 1998

본 연구에서는 PC환경에서 축척 1:5,000의 지형도를 원 데이터로 하여 등고선 레이어를 만들고, 이를 이용하여 TIN과 GRID 데이터 구조 기반의 수치지형모델을 생성하여 지령분석에 관한 연구를 수행하였다. 지성선(breakline) 을 고려하지 않은 경우와 고려한 경우에 대해 각각의 데이터 구조 기반별 수치지형모델을 생성하고 실행 시간, 저장 파일의 크기, 평균 표고, 표준 편차 등을 분석하였으며, 격자 데이터 구조 기반의 경우 $5\times{5m},\;l0\times{10m},\;15\times{15m},\;l0\times{30m},\;45\times{45m},\;60\times{60m}$의 셀 크기를 고려한 사면경사도와 경사방위도를 생성하여 비교ㆍ분석하였다 실험 결과 다음과 같은 결론을 얻었다. TIN과 GRID기반의 DTM을 생성시에는 지정의 기복이 심할수록 지정특징인 지성선을 고려하는 것이 실제지형을 보다 정교하게 표현하는 방법임을 알 수 있었다. 격자 크기를 증가시켜도 평균표고는 큰 변화를 나타내지 않았다. 그러나 격자 크기가 커질수록 실행시간은 상당히 단축되었고 저장공간 또한 매우 작아짐을 알 수 있었다. 따라서 DTM을 응용분야에 보다 효율적으로 적용하기 위해서는 최적의 격자크기를 결정하는 것이 선결 과제임을 알 수 있었다. 사면경사각과 경사방위각 계산을 수행한 결과 대조적인 작은 변화를 나타냈다. 사면경사각은 격자 크기가 커질수록 작아지는 경향을 나타낸 반면 경사방위각은 격자 크기가 커질수록 커지는 경향을 나타냈다.

• IMMUNE NETWORK
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• 제6권4호
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• pp.185-191
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• 2006

Background: Based on outstanding progresses in animal experiments, vaccines for some human tumors have been developed. However, clinical effects of these vaccines have been far below than expected. This discrepancy might come from differences between animal models and human patients with respect to immunocompetency. The immune status of mice after tumor inoculation has not been well studied, which make us cautious in interpreting and applying the results from mice to human. We evaluated cell-mediated immune responses in mice after tumor cell inoculation. Methods: Mice were inoculated with TA3Ha, CT26, or 4T1. Delayed-type hypersensitivity (DTH) responses were induced 2-4 weeks after inoculation using 2,4-dinitro-1-fluorobenzene as an antigen. The relationships between the severity of DTH responses and the duration of tumor inoculation or the size of tumor mass were analyzed. Results: In T A3Ha groups, DTH response was elevated 2 weeks after inoculation, but depressed after 4 weeks, compared to the control group. When analyzed based on the sizes of tumor masses elicited, DTH responses were inversely related to the mass size, especially in those greater than 10 mm in diameter. In CT26 groups, while the duration after inoculation did not affect the severity of DTH responses, those with large mass showed depressed responses regardless the duration of inoculation. 4T1 cells grew so slowly that the size of tumor mass was small even 4 weeks after inoculation, and this group showed much higher DTH responses compared to that of tumor-free group. Conclusion: At least in an experimental setting where tumor model was induced by inoculating tumor cell lines into immunologically competent mice, the host immune response was elevated in early stage, and then depressed in late stage when the mass grew over a critical size.

• 한국전자파학회논문지
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• 제19권7호
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• pp.791-799
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• 2008

본 논문에서는 $DC{\sim}18\;GHz$에서 동작하는 GTEM 셀 설계를 위한 전자파 모델링과 회로망 해석 기법을 제시하였다. GTEM 셀의 동축선 입력 급전부의 모드 변환기, 전송선 길이가 5미터인 확장형 사각 동축선 그리고 전송부 동축선의 전류와 입력단으로부터 입사되는 전자파를 정합시킬 수 있는 종단 부하로 구성되는 3차인 전자파 수치 해석 모델을 제시하였다. GTEM cell의 급전부, 전송선부, 종단 부하부에 대한 등가 회로망 모델을 제시하였으며, 이를 이용하여 전자파 수치 해석 모델에서 구해진 산란 계수로부터 GTEM cell의 성능 평가 지수인 입력 반사 계수를 계산할 수 있도록 하였다. $DC{\sim}18\;GHz$에서 동작하는 $5.0{\times}2.5{\times}1.7\;m$ 크기의 GTEM cell을 설계, 제작, 성능 평가하여 제안한 기법의 효용성을 입증하였다.