• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2006년도 High Temperature Superconductivity Vol.XVI
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• pp.92-92
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• 2006

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2005년도 High Temperature Superconductivity Vol.XV
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• pp.92-92
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• 2005

• 한국정보과학회논문지:시스템및이론
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• 제34권5_6호
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• pp.238-248
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• 2007

최근 PDA의 대중화, 텔레메틱스 산업의 발전에 따라 제한된 저장장치를 갖는 모바일 임베디드 시스템에서 PC와 같은 다양한 소프트웨어를 사용하고자하는 수요가 늘어나고 있다. 그에 따라 소프트웨어 스트리밍 서비스의 필요성이 증가하고 있으나 소프트웨어를 속도가 느린 무선 네트워크를 통해 블록단위로 전송받아 실행속도가 느린 문제점이 있다. 그리하여 이를 보완해주는 선인출 알고리즘이 필요하다. 본 논문에서는 기존에 연구된 선인출 알고리즘인 최근 접근 블록 알고리즘(LS)과 PPM 기반 알고리즘을 소프트웨어 스트리밍 서비스에 적용시켜 성능을 측정하고 분석한 결과를 토대로 고안된 확률 기반 다중 접근 블록(PMS) 알고리즘을 제안한다. LS의 적중률은 60%정도로 낮지만 메모리 사용량이 적다. 그에 반해 PPM 기반 알고리즘은 메모리 사용량은 많지만 96%이상의 높은 적중률을 보인다. PMS는 블록 단위의 소프트웨어 스트리밍 서비스의 특징과 PPM 기반 알고리즘의 특성을 이용하여 LS의 단점을 보완해 N개의 접근 블록을 확률을 기반으로 저장하고 선인출에 이용한다. 이러한 PMS는 보다 적은 공간오버헤드를 가지면서 PPM 기반 알고리즘과 비슷한 적중률을 나타내 높은 메모리 효율을 나타낸다.

• 한국산학기술학회논문지
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• 제5권5호
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• pp.442-446
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• 2004

스웨이징(swaging)제조 공정의 컴퓨터 시뮬레이션에 관한 연구를 수행하기 위하여 상용 소프트웨어를 사용하였다. 시행오차를 통하여 획득한 경험에 기반을 두어 튜브 스웨이징 공정의 시뮬레이션이 이루어졌으며, 변형 경화 지수(strain hardening exponent) n과 소성계수(plastic modulus) K는 튜브재료의 실제 인장 측정 시험을 통하여 얻어졌다. 두 종류의 서로 다른 다이와 튜브 형상을 사용하여 비교하였다. 전처리는 HyperMesh(r), 해석은 LS-DYNA(r), 후처리는 LS-TAURUS(r)를의 상용 소프트웨어를 사용하였으며, 본 연구에서 얻어진 결과들을 문헌에서 이용 가능한 결과들과 비교하였다.

• Ocean Science Journal
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• 제42권2호
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• pp.89-102
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• 2007

The surface circulation of northern South China Sea (hereafter SCS) for the period 1987-2005 was studied using the data of more than 500 satellite-tracked drifters and wind data from QuikSCAT. The mean flow directions in the northern SCS except the Luzon Strait (here after LS) during the periods October_March was southwestward, and $April{\sim}September$ northeastward. A strong northwestward intrusion of the Kuroshio through the LS appears during the $October{\sim}March$ period of northeasterly wind, but the intrusion became weak between April and September. When the strong intrusion occurred, the eddy kinetic energy (EKE) in the LS was $388cm^2/s^2$ which was almost 2 times higher than that during the weak-intrusion season. The volume transport of the Kuroshio in the east of the Philippines shows an inverse relationship to that of the LS. There is a six-month phase shift between the two seasonal phenomena. The volume transport in the east of the Philippines shows its peak sis-month earlier faster than that of the LS. The strong Kuroshio intrusion is found to be also related to the seasonal variation of the wind stress curl generated by the north easterly wind. The negative wind stress curl in the northern part of LS induces an anticyclonic flow, while the positive wind stress curl in the southern part of LS induces a cyclonic flow. The northwestward Kuroshio intrusion in the northern part of LS happened with larger negative wind stress curl, while the westward intrusion along $20.5^{\circ}N$ in the center of the LS occurred with weaker negative wind stress curl.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 추계학술대회 논문집
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• pp.121-122
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• 2013

본 논문에서는 수출형 소 용량 태양광 인버터를 설계, 제작하였으며, 실제 제품을 제작하였다. 해당 제품은 VDE-AR-N_4105 및 VDE V 0126-1-1규정에 준하는 무변압기 방식 태양광 인버터로서 안정적이며 신뢰성 있는 동작을 할 수 있도록 절연레벨, 누설전류 및 기타 계통의 안정성 판단을 2개의 CPU에서 동시에 감시하도록 설계하였다. 또한 높은 IP등급을 만족하도록 설계되어 실외에서도 안정적이고 신뢰성 있는 동작을 할 수 있도록 설계하였다.

• Korean Journal of Radiology
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• 제23권2호
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• pp.180-188
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• 2022

Objective: To validate the performance of 3T spin-echo echo-planar imaging (SE-EPI) magnetic resonance elastography (MRE) for staging hepatic fibrosis in a large population, using surgical specimens as the reference standard. Materials and Methods: This retrospective study initially included 310 adults (155 undergoing hepatic resection and 155 undergoing donor hepatectomy) with histopathologic results from surgical liver specimens. They underwent 3T SE-EPI MRE ≤ 3 months prior to surgery. Demographic findings, underlying liver disease, and hepatic fibrosis pathologic stage according to METAVIR were recorded. Liver stiffness (LS) was measured by two radiologists, and inter-reader reproducibility was evaluated using the intraclass correlation coefficient (ICC). The mean LS of each fibrosis stage (F0-F4) was calculated in total and for each etiologic subgroup. Comparisons among subgroups were performed using the Kruskal-Wallis test and Conover post-hoc test. The cutoff values for fibrosis staging were estimated using receiver operating characteristic (ROC) curve analysis. Results: Inter-reader reproducibility was excellent (ICC, 0.98; 95% confidence interval, 0.97-0.99). The mean LS values were 1.91, 2.41, 3.24, and 5.41 kPa in F0-F1 (n = 171), F2 (n = 26), F3 (n = 38), and F4 (n = 72), respectively. The discriminating cutoff values for diagnosing ≥ F2, ≥ F3, and F4 were 2.18, 2.71, and 3.15 kPa, respectively, with the ROC curve areas of 0.97-0.98 (sensitivity 91.2%-95.9%, specificity 90.7%-99.0%). The mean LS was significantly higher in patients with cirrhosis (F4) of nonviral causes, such as primary biliary cirrhosis (9.56 kPa) and alcoholic liver disease (7.17 kPa) than in those with hepatitis B or C cirrhosis (4.28 and 4.92 kPa, respectively). There were no statistically significant differences in LS among the different etiologic subgroups in the F0-F3 stages. Conclusion: The 3T SE-EPI MRE demonstrated high interobserver reproducibility, and our criteria for staging hepatic fibrosis showed high diagnostic performance. LS was significantly higher in patients with non-viral cirrhosis than in those with viral cirrhosis.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.454-458
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• 2007

Nonpoint source (NPS) pollution is a serious problem causing the degradation of soil and water quality. Concentrated overland flow is the primary transport mechanism for a large amount of NPS pollutants from hillslope areas to downslope areas in a watershed. In this study, a soil erosion model, nLS model, to identify transitional overland flow regions (i.e., ephemeral gully head areas) was developed using the kinematic wave overland flow theory. Spatial data, including digital elevation models (DEMs), soil, and landcover, were used in the GIS-based model algorithm. The model was calibrated and validated using gully head locations in a large agricultural watershed, which were identified using 1-m aerial photography. The model performance was better than two previous approaches; the overall accuracy of the nLS model was 72 % to 87 % in one calibration subwatershed and the mean overall accuracy was 75 to 89 % in four validation subwatersheds, showing that the model well predicted potential transitional erosion areas at different watersheds. However, the user accuracy in calibration and validation was still low. To improve the user accuracy and study the effects of DEM resolution, finer resolution DEMs may be preferred because DEM grid is strongly sensitive to estimating model parameters. Information gained from this study can improve assessing soil erosion process due to concentrated overland flow as well as analyze the effect of microtopographic landscapes, such as riparian buffer areas, in NPS control.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4067-4071
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• 2021

The ¹³C (α,n)¹⁶O reaction cross-section is important data for nuclear physics, astrophysical, and neutrino physics experiments, however, they exhibit uncertainties due to the discrepancies in the experimental data. In this study, using the Nedis-2m program code, the energy spectrum of α-induced neutrons in a thin carbon target was calculated and the corresponding reaction cross-section was refined in the alpha particle energy range of 5-8 MeV. The results were used to calculate the intensity and energy spectrum of background neutrons produced in the liquid scintillator of KamLAND. The results will be useful in a variety of astrophysical and neutrino experiments especially those based on LS or Gd-LS detectors.

• 한국컴퓨터정보학회논문지
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• 제19권10호
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• pp.13-21
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• 2014

집합 커버링 문제는 대표적인 조합 최적화 문제들 중 하나로서 n개의 열로부터 일부를 선택하여 m개의 행을 커버하되 비용을 최소화하는 문제로 정의된다. 본 논문에서는 집합 커버링 문제를 해결하기 위한 정수 계획법 기반 지역 탐색의 적용 방안을 제시하고 있다. 정수계획법 기반 지역 탐색은 이웃해를 탐색하여 현재해를 반복적으로 개선하는 지역 탐색 기법의 일종으로서 이웃해를 생성하기 위한 알고리즘으로 정수계획법을 사용한다. 본 논문에서 제시한 기법의 효과를 검증하기 위해 OR-Library의 테스트 데이터를 대상으로 실험을 수행하였다. 실험 결과, 모든 테스트 데이터에 있어서 정수계획법 기반 지역 탐색을 통해 지금까지 알려진 가장 좋은 해를 탐색할 수 있었다. 특히 4개의 테스트 데이터에 대해서는 지금까지 알려진 가장 좋은 해보다 더 좋은 해를 도출할 수 있음을 확인할 수 있었다.