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이충성,조유희,임신열,류경하,이원균 한국신뢰성학회 2023 신뢰성응용연구 Vol.23 No.4
Purpose: This study conducts reliability testing on a widely used industrial pilot check valve, adhering to the International Organization for Standardization (ISO) 19973-5 standard. The testing process identifies and reviews issues observed during the tests. Methods: ISO 19973-5, reliability testing procedures were implemented, and accelerated tests were conducted to derive acceleration factors. These tests included assessing the maximum operational frequency and conducting maximum pressure acceleration tests on the researched product. Results: The standard’s circuit definitions were unclear, prompting modifications in the test circuit and failure definitions considering the operating environment. Life tests were performed on 29 samples with varying operational frequencies and pressures. Analysis of data from 8 faulty samples revealed a shape parameter (β) of 1.69, using the common slope method. The characteristic life (θ) at normal lifespan was determined to be 14,633,538 cycles, with a pressure acceleration factor of 1.75 and a frequency acceleration factor of 0.28. Conclusion: In the current industrial sector, product defects are assessed, and defect criteria are established using standards such as ISO and Korean Standards. However, there is a recognized need to establish appropriate evaluation criteria for products by considering factors such as the operating circuit and conditions of the product.
이충성,지남철 조선대학교 1994 The Medical Journal of Chosun University Vol.19 No.2
Cyclic Strabismus is a relatively rare disorder of ocular motility that is reported to occur in one in 3000 to 5000 cases of strabismus. It is characterized by the fact that ocular deviation is present on a rhythmic basis. The type of deviation is classically a large-angle exotropia alternating with orthophoria or a small-angle esodeviation on a 48-hour cycle. In the present study, one case of cyclic esotropia in a 4-year-old male who represents periodic ocular deviation on a alternate daily was discussed. The periodic esodeviation was treated with bimedial rectus recession.
나카가미 페이딩 채널에서 선택 합성 다이버시티를 적용한 FH/MFSK 시스템의 성능분석
이충성,김항래,김남,Lee, Chung-Seong,Kim, Hang-Rae,Kim, Nam 한국전자파학회 2000 한국전자파학회논문지 Vol.11 No.7
본 논문에서는 나카가미 패이딩 채널에서 FH/MFSK 시스템에 선택 다이버시티를 적용하였을 경우의 시스템 성능을 분석한다. 선택 합성(selection combining)후의 신호대 잡음비(SNR)로부터 제거확률을 유도하고 FH/MFSK 시스템의 성분분석을 위해 사용자수(M), SNR, 나카가미 페이딩(m), 다이버시티 가지의 수(D)와 같은 파라메더들을 사용한다. m이 1인 경우, 비트에러율(BER)은 각각 D=1에서 1.0$\times$10-3이고 D=2에서 1.0$\times$10-4으로 10배만큼 감소함을 알 수 있다. m이 2인 경우, BER은 D가 증가하더라도 일정한 값을 갖는다는 것을 또한 알 수 있다. D가 2인 경우, SNR이 15dB와 25dB일 때의 시스템 용량은 다이버시티를 고려하지 않은 용량보다 각각 75%와 20% 증가된다. In this paper, the system performance with the selection diversity, which is applied to the FH/MFSK system in Nakagami fading channel, is analyzed. The deletion probability is derived from the received signal to noise ratio(SNR) after selection combining and the parameters such as the number of users(M), SNR, Nakagami fading figure(m), and the number of diversity branches(D) is used for the performance analysis of the FH/MFSK system. Assuming that m set 1, it is observed that the bit error rate(BER) is 1.0$\times$$10^{-3}$ and 1.0$\times$$10^{-4}$ at D =1(no diversity) and D=2, respectively, and then is decreased by 10 times. Assuming that m set 2, it is also shown that the BER has a constant value although D is increased. In the case of D=2, the system capacity is more 75% and 20% than that considering no diversity at SNR=15 dB and 25 dB, respectively.
도시지역과 전원지역의 홍수피해 비교를 통한홍수피해산정방법의 적정성 평가
이충성,심명필,최승안,장준경 국토연구원 2006 국토연구 Vol.48 No.-
Adequacy Evaluation of Flood Damage Assessment Models by Comparing Flood Damages between Urban and Rural Area
이충성,유재영,여규동,이상원 국토연구원 2010 국토연구 Vol.64 No.-
Since the river usually flows over several regions, there may have the cost allocation issues for constructing flood protection measures in flood mitigation management. The purpose of this study is to suggest an alternative for the solution of a cost allocation issue that usually occurs at planning projects for flood mitigation management. As a case study, we selected the cost allocation issue in constructing flood protection measures in Najinpo and Gyeoyang rivers, which are tributaries of Han river and flow through Incheon in upstream and Gimpo in downstream, and suggested the inter-regional cost allocation method from the case study. The theoretical approach for the cost allocation was based on the cooperative game theory, and in terms of methodology, we used the SCRB (Separable Cost Remaining Benefit) and Shapley value method which are comparatively easy to apply. From the study, the cost allocation ratio between upstream and downstream regions are approximately 54% vs. 46% in Najinpo river basin and 70% vs. 30% in Gyeoyang river basin respectively. This study is expected to provide an alternative for solving the similar cost allocation problems for flood mitigation management which may be occurred frequently in the future between two or more regions, especially upstream and downstream. 일반적으로 하천은 여러 지역에 걸쳐 흐르기 때문에 하천 치수관리를 위한 홍수방어시설물들을 건설할 때에 대해 발생하는 비용에 대하여 상·하류 지역 간 비용배분의 문제가 발생하게 된다. 본 연구의 목적은 유역 내 치수관리를 위한 사업계획 시 발생하는 비용배분 문제해결의 대안을 제시하는 것이다. 이를 위한 사례연구로서 본 연구는 한강 지류인 나진포천 및 계양천의 홍수방어시설 건설에 따른 비용배분 문제를 선정하였고, 상류인 인천시와 하류인 김포시 간의 지역 간 비용배분 방안을 제시하였다. 비용배분의 해법을 위한 이론적 전개는 협조적 게임이론을 바탕으로 하였고, 방법론 측면에서는 비교적 적용이 간편한 분리비용잔여편익법 및 샤플리법을 사용하였다. 분석결과, 상류와 하류 간의 비용배분 비율은 나진포천 유역에서 약 54% : 46%, 계양천 유역에서 약 70% : 30%로 각각 나타났다. 본 연구는 둘 이상의 지역 간, 특히 상류와 하류 간에 향후 빈번하게 발생될 것으로 보이는 유사한 하천 치수관리 비용배분 문제의 해결을 위한 대안을 제시할 것으로 기대된다.