• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.931-934
• /
• 2001

GaN nanowires has much interest as one-dimensional materials for blue light LED. GaN-based materials have been the subject of intensive research for blue light emission and high temperature/high power electronic devices. In this letter, the synthesis of GaN nanowires by the reaction of mixture of GaN nanowires by the reaction of mixture of Ga meta and GaN powder with NH$_3$ using thermal chemical vapor deposition is reported. X-ray diffraction, energy dispersive x-ray spectrometer, scanning electron microscopy, and transmission electron microscopy indicate that those GaN nanowires with hexagonal wurtzite structure were about 60nm in diameter and up to several hundreds of micrometers in length.

• Journal of Information Technology Applications and Management
• /
• 제12권1호
• /
• pp.125-140
• /
• 2005

Nowadays, we have many embedded systems which store and process multimedia data. For multimedia systems using hard disks as storage media such as DVR, existing file systems are not the right choice to store multimedia data in terms of cost. performance and reliability. In this study we designed a reliable file system with very high performance for embedded multimedia applications. The proposed file system runs with quite simple disk layout to reduce time to initialize and to recover after power failures, uses a large data block to speed up the sequential accesses, incorporates a time-based indexing scheme to improve the time-based random accesses and boosts reliability by backing up the important meta data on a small NVRAM. We implemented the file system on a Linux-based DVR and verified the performance by comparing with existing file systems.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.516-518
• /
• 1995

This paper presents an integrated fault diagnosis expert system for power systems. The proposed system diagnoses various faults occurred in both substations and transmission lines even in the case that substation fault is spreaded over the network. To cope with this problem, A meta-inference method is proposed. This scheme shares same the data structure with the pre-developed intelligent operational aid expert system installed in a practical sub-control center, without modification. This advanced integrated diagnosis system is developed using a low cost personal computer owing to the special modular programming technique. Case studies show a promising possibility of the proposed method.

• ETRI Journal
• /
• 제45권3호
• /
• pp.433-447
• /
• 2023

Critical issues such as connection congestion, long transmission delay, and packet loss become even worse during epidemic, disaster, and so on. In this study, a link load balancing method is proposed to address these issues on the data plane, a plane of the software-defined network (SDN) architecture. These problems are NP-complete, so a meta-heuristic approach, discrete particle swarm optimization, is used with a novel hybrid cost function. The superiority of the proposed method over existing methods in the literature is that it provides link and switch load balancing simultaneously. The goal is to choose a path that minimizes the connection load between the source and destination in multipath SDNs. Furthermore, the proposed work is dynamic, so selected paths are regularly updated. Simulation results prove that with the proposed method, streams reach the target with minimum time, no loss, low power consumption, and low memory usage.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권3호
• /
• pp.1001-1006
• /
• 2015

Background: With development and application of new and effective anti-cancer drugs, the median survival post-progression (SPP) is often prolonged, and the role of the median SPP on surrogacy performance should be considered. To evaluate the impact of the median SPP on the correlation between progression-free survival (PFS) and overall survival (OS), we performed simulations for treatment of four types of cancer, advanced gastric cancer (AGC), metastatic colorectal cancer (MCC), glioblastoma (GBM), and advanced non-small-cell lung cancer (ANSCLC). Materials and Methods: The effects of the median SPP on the statistical properties of OS and the correlation between PFS and OS were assessed. Further, comparisons were made between the surrogacy performance based on real data from meta-analyses and simulation results with similar scenarios. Results: The probability of a significant gain in OS and HR for OS was decreased by an increase of the SPP/OS ratio or by a decrease of observed treatment benefit for PFS. Similarly, for each of the four types of cancer, the correlation between PFS and OS was reduced as the median SPP increased from 2 to 12 months. Except for ANSCLC, for which the median SPP was equal to the true value, the simulated correlation between PFS and OS was consistent with the values derived from meta-analyses for the other three kinds of cancer. Further, for these three types of cancer, when the median SPP was controlled at a designated level (i.e., < 4 months for AGC, < 12 months for MCC, and <6 months for GBM), the correlation between PFS and OS was strong; and the power of OS reached 34.9% at the minimum. Conclusions: PFS is an acceptable surrogate endpoint for OS under the condition of controlling SPPs for AGC, MCC, and GBM at their limit levels; a similar conclusion cannot be made for ANSCLC.

• 한국콘텐츠학회논문지
• /
• 제17권7호
• /
• pp.546-556
• /
• 2017

문화와 같은 소프트파워의 발견과 적극적인 활용을 통해 도시 재생과 지역경제 활성화를 실현하려는 다양한 전략들이 추진되고 있으나, 많은 경우 지역의 경험과 전문성 부족으로 인해 지역발전으로 충분히 연결되지 못하고 있다. 이 점에 착안해 본 연구는 다수의 지역문화자원 활용 사례연구를 대상으로 한 메타분석(Meta-analysis)과 전문가를 대상으로 한 계층화분석기법(Analytic Hierarchy Process)을 적용해 문화자원에 기반을 둔 지역발전전략에 영향을 미치는 요인들을 발견해 보았다. 분석결과, 총 61건의 선행연구들로 부터 278개의 직 간접 요인들을 추출하였고, 이들을 대표하는 핵심내용으로 통 폐합한 후 공통속성을 지닌 요인들을 재분류하는 과정을 거쳐 4개 범주(문화자원 발굴 및 활용, 제도적 기반 구축, 지역내부 역량 강화, 참여 및 네트워크 확대)에 모두 26개 중요 영향요인을 도출하였다. 또한 빈도 및 중요도 분석결과는 이들 범주 중 '문화자원 발굴 및 활용'과 관련된 요인들이 문화자원 활용을 통한 지역발전전략 추진과정과 결과에 상대적으로 더 큰 영향을 미칠 수 있다는 것을 보여주고 있다. 이는 문화자원을 활용한 지역발전전략의 성공여부는 다양한 요인들의 복합적인 작용해 의해 결정되지만, 잠재력과 경쟁력을 지닌 문화자원의 분포와 함께, 그것을 개발하고 가치를 높일 수 있는 활용능력을 갖추는 일이 무엇보다 중요하다는 시사점을 준다. 본 연구는 다수 선행사례연구를 대상으로 영향요인 분석을 시도했다는 점에서 나름의 의미를 지닌다.

• 한국전자파학회논문지
• /
• 제23권3호
• /
• pp.343-354
• /
• 2012

본 논문에서는 무선 전력 전송을 위한 다양한 스파이럴 구조의 영자 공진기들을 설계하였다. 메타 물질 전송 선로의 영차 공진은 무한 파장의 특징을 가지기 때문에 공진기의 크기에 상관없이 디자인이 가능한 장점을 가진다. 또한, 무선 전력 전송에서 고효율의 전송 효율을 얻기 위해서는 공진기의 Q-factor와 공진기간의 결합 계수가 커야 한다. 따라서 제안된 영차 공진기들은 영차 공진을 유도하기 위해 스파이럴 형태의 인덕터와 집중 캐패시터 소자를 사용하였고, parametric study와 R, L, C 회로 분석을 통해 높은 Q-factor를 얻기 위한 최적의 디자인을 찾고자 하였다. 최적화된 공진기들은 기존의 스파이럴 공진기와 모의 실험을 통해 비교되었으며, 최적화된 공진기들 중 제작된 공진기의 크기는 $20cm{\times}20cm{\times}8cm$($0.009{\lambda}_0{\times}0.009{\lambda}_0{\times}0.004{\lambda}_0$)이고, 13.56 MHz 대역의 주파수와 40 cm 거리에서 80 %의 전송 효율이 측정되었다.

• 자원ㆍ환경경제연구
• /
• 제21권3호
• /
• pp.543-572
• /
• 2012

본 연구는 2000년부터 현재까지 한국과 일본의 에너지 수급 현황을 비교하는 한편, 2000년 이후 발표된 중장기 저탄소 에너지 계획 및 시나리오 관련 문헌들을 검토하였다. 에너지수급 측면에서 한국과 일본은 모두 에너지 수입의존도가 높고, OECD 국가들 중에서 제조업의 비중이 높으며, 전력 계통은 외부와 고립된 시스템이며, 발전량에서 원전이 차지하는 비중이 높고, 재생에너지 잠재량은 높지만 실제 생산량은 낮다는 점 등이 유사하다. 차이점은 에너지 소비량 추세가 일본은 감소하는 반면, 한국은 증가하고 있으며, 지역간 전력 교류가 한국은 가능한 반면, 일본은 그렇지 않으며, 향후 원자력 확대가 일본은 어려울 전망인 반면, 한국의 현 정부는 원자력 확대 방침을 유지하고 있다는 점 등이다. 후쿠시마 원전 사고 전후로, 일본과 한국의 정부에서 수립한 에너지계획은 원자력을 약 2배 수준으로 확대할 계획으로 하고 있었지만, 시민사회에서는 에너지 수요 저감, 원자력의 단계적 축소, 재생에너지 확대를 내용으로 하는 시나리오들을 발표하였다. 본 연구는 일본과 한국의 중장기 에너지 시나리오 및 계획 수립 연구에 활용될 수 있을 것이다.

• Journal of Welding and Joining
• /
• 제20권6호
• /
• pp.30-30
• /
• 2002

It has been reported that the creep characteristics on weldment which is composed of weld metal(W.M), fusion line(F.L), heat-affected zone(HAZ), and base meta(B.M) could be unpredictably changed in severe service conditions such as high temperature and high pressure. However, the studies done on creep damage in power plant components have been mostly conducted on B.M and not the creep properties of the localized microstructures in weldment have been thoroughly investigated yet. In this paper, it is investigated the creep characteristics for three microstructures like coarse-grain HAZ(CGHAZ), W.M, and B.M in X20CrMoV121 steel weldment by the small punch-creep-(SP-Creep) test using miniaturized specimen(l0×10×0.5mm). The W.M microstructure possesses the higher creep resistance and shows lower creep strain rate than the B.M and CGHAZ. In the lower creep load the highest creep strain rate is exhibited in CGHAZ, whereas in the higher creep load the B.M represents the high creep strain rate. The power law correlation for all microstructures exists between creep rate and creep load at 600℃. The values of creep load index (n) based on creep strain rate for B.M, CGHAZ, and W.M are 7.54, 4.23, and 5.06, respectively and CGHAZ which shows coarse grains owing to high welding heat has the lowest creep loade index. In all creep loads, the creep life for W.M shows the highest value.

• Journal of Welding and Joining
• /
• 제20권6호
• /
• pp.754-761
• /
• 2002

It has been reported that the creep characteristics on weldment which is composed of weld metal(W.M), fusion line(F.L), heat-affected zone(HAZ), and base meta(B.M) could be unpredictably changed in severe service conditions such as high temperature and high pressure. However, the studies done on creep damage in power plant components have been mostly conducted on B.M and not the creep properties of the localized microstructures in weldment have been thoroughly investigated yet. In this paper, it is investigated the creep characteristics for three microstructures like coarse-grain HAZ(CGHAZ), W.M, and B.M in X20CrMoV121 steel weldment by the small punch-creep-(SP-Creep) test using miniaturized specimen($10{\times}10{\times}0.5mm$). The W.M microstructure possesses the higher creep resistance and shows lower creep strain rate than the B.M and CGHAZ. In the lower creep load the highest creep strain rate is exhibited in CGHAZ, whereas in the higher creep load the B.M represents the high creep strain rate. The power law correlation for all microstructures exists between creep rate and creep load at $600^{\circ}C$. The values of creep load index (n) based on creep strain rate for B.M, CGHAZ, and W.M are 7.54, 4.23, and 5.06, respectively and CGHAZ which shows coarse grains owing to high welding heat has the lowest creep loade index. In all creep loads, the creep life for W.M shows the highest value.