• 제목/요약/키워드: Electronic package

검색결과 388건 처리시간 0.021초

부품선택이 존재하는 직렬시스템의 신뢰성 최적화 해법 (Solution Methods for Reliability Optimization of a Series System with Component Choices)

  • 김호균;배창옥;김재환;손주영
    • 대한산업공학회지
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    • 제34권1호
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    • pp.49-56
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    • 2008
  • Reliability has been considered as an important design measure in various industrial systems. We discuss a reliability optimization problem with component choices (ROP-CC) subject to a budget constraint. This problem has been known as a NP-hard problem in the reliability design fields. Several researchers have been working to find the optimal solution through different heuristic methods. In this paper, we describe our development of simulated annealing (SA) and tabu search (TS) algorithms and a reoptimization procedure of the two algorithms for solving the problem. Experimental results for some examples are shown to evaluate the performance of these methods. We compare the results with the solutions of a previous study which used ant system (AS) and the global optimal solution of each example obtained through an optimization package, CPLEX 9.1. The computational results indicate that the developed algorithms outperform the previous results.

철도택배의 물류정보시스템 구축에 관한 연구

  • 이철식;송장근
    • 한국경영과학회:학술대회논문집
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    • 한국경영과학회 2001년도 추계학술대회 논문집
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    • pp.7-10
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    • 2001
  • The development of information communication technology leads the growth of logistic industry including delivery service as well as electronic commerce. The researchers predict that it will be still improving for the next several years. The logistic information system of railroad courier has been growing for a long time with small-package delivery transportation which is similar to the land-road delivery system. Despite of the long-time growth, it is recently in pain of the great loss since the 1990's, due to the failure to satisfy the customer's need for door-to-door delivery service. But the logistic information system of railroad still has the great potential. There are so many benefits such as timeliness, Punctuality, speed, multi-node storage base, transportation efficiency, energy frugality, environmental sociability, and so on. If the railroad logistic system plays a role of a portion of the nation-wide logistic with other logistic system, the synergy through the balancing logistic will also get much of international competitive advantages. So the objective of this research is to design the model and prototype of the web-based logistic system from which railroad service provider(Korean National Railroad), delivery service providers, and the customers can share the best effective delivery information.

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Active Infrared Thermography for Visualizing Subsurface Micro Voids in an Epoxy Molding Compound

  • Yang, Jinyeol;Hwang, Soonkyu;Choi, Jaemook;Sohn, Hoon
    • 비파괴검사학회지
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    • 제37권2호
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    • pp.106-114
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    • 2017
  • This paper presents an automated subsurface micro void detection technique based on pulsed infrared thermography for inspecting epoxy molding compounds (EMC) used in electronic device packaging. Subsurface micro voids are first detected and visualized by extracting a lock-in amplitude image from raw thermal images. Binary imaging follows to achieve better visualization of subsurface micro voids. A median filter is then applied for removing sparse noise components. The performance of the proposed technique is tested using 36 EMC samples, which have subsurface (below $150{\mu}m{\sim}300{\mu}m$ from the inspection surface) micro voids ($150{\mu}m{\sim}300{\mu}m$ in diameter). The experimental results show that the subsurface micro voids can be successfully detected without causing any damage to the EMC samples, making it suitable for automated online inspection.

말씨와 활동성의 체질특성 문항에 대한 통계적 분석 (A Statistical Analysis of the questionnaire concerning Sasang Constitutional Characteristics on 'Pattern of speech and activity')

  • 문성택;이시우;김홍기;김종열
    • 한국한의학연구원논문집
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    • 제13권1호통권19호
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    • pp.85-92
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    • 2007
  • To evaluate the suitability and effectiveness of the questionnaire concerning personal properties on 'pattern of speech and activity' according to the Sasang constitution that were used in Iksan Wonkwang Oriental Medicine, we analyzed the data of 1,335 patients obtained through the electronic chart in the aspect of 'relative discrimination ability' to Sasang constitutions and 'response ratio' using statistical Package SPSS. In categories of 'speech pattern', No.2 (speak mildly and softly) was effectively discriminating Soeum type. No.4 (talkative) and No.7 (speak fast) were effective factors for the discrimination of Soyang type, though No.4 (talkative) was needed to be improved in response ratio. The category of 'activity pattern' has shown high response ratio but low discriminating power. However, No.2 (keep staying home but avoid going out) in this category was effectively discriminating Soeum type. The discriminating power of 'pattern of speech and activity' for the age group less than 20 years old was too low, so it is necessary to develop the questionnaire for the elementary to high school students as well as for the preschoolers.

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고온고습 전원인가 시험에서 Cl에 의한 이온 마이그레이션 불량 (Chlorine effect on ion migration for PCBs under temperature-humidity bias test)

  • 허석환;신안섭
    • Journal of Welding and Joining
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    • 제33권3호
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    • pp.47-53
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    • 2015
  • By the trends of electronic package to be more integrative, the fine Cu trace pitch of organic PCB is required to be a robust design. In this study, the short circuit failure mechanism of PCB with a Cl element under the Temperature humidity bias test ($85^{\circ}C$/85%RH/3.5V) was examined by micro-structural study. A focused ion beam (FIB) and an electron probe micro analysis (EPMA) were used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $CuCl_x$ were formed and grown on Cu trace during the $170^{\circ}C$/3hrs and that $CuCl_x$ was decomposed into Cu dendrite and $Cl_2$ gas during the $85^{\circ}C$/85%RH/3.5V. It is suggested that Cu dendrites formed on Cu trace lead to a short circuit failure between a pair of Cu traces.

기초간호과학교육을 위한 웹기반 학습프로그램 개발 및 효과 (Development and Evaluation of a Web-Based Instructional Program on Basic Nursing Science for Nursing Students)

  • 유지수;황애란;홍해숙;박미정
    • Journal of Korean Biological Nursing Science
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    • 제3권2호
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    • pp.63-68
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    • 2001
  • Increasing interest in computer-mediated learning technologies has prompted educators to incorporate them into many learning environments ; however, there is still little evaluative evidence to support their effectiveness. This report describes the development and evaluation of a web-based instructional program on basic nursing science for nursing students. Researcher-designed questionnaires were used to assess the characteristics of our students, and to solicit their ratings of the instructional program on ease of use, accuracy of content, clarity of content, interest, and convenience of the program, using 5-point Likert scales. The respondents indicated that the package was easy and convenient to use, with high technical quality, and of a level challenging to some but not all of the students. On-line quizzes were most highly rated. Also it was confirmed that frequent users of electronic bulletin board showed much higher achievement score than that of nonfrequent users. It was also found that the effect of cyber education was dependent on the active participation of the students. These data suggest that the use of web-based instructional program as a distance education strategy can be an effective method for nursing students and nurses.

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소셜미디어 이용동기가 만족과 재방문의도에 미치는 영향 : 농촌체험마을 이용자를 중심으로 (Effect of Social Media Use Motivation on Satisfaction and Revisit Intention : Focused on Rural Tourism Visitors)

  • 문영주;정철호
    • 한국콘텐츠학회논문지
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    • 제11권9호
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    • pp.202-211
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    • 2011
  • 본 연구는 농촌체험마을의 소셜미디어 이용동기가 만족과 재방문의도에 미치는 영향을 규명하기 위한 연구이다. 연구 분석을 위해 농촌체험마을의 소셜미디어 사이트 이용경험이 있는 397명의 표본자료가 활용되었으며 연구 분석을 위해 PASW18과 Lisrel8.54의 통계분석 도구가 활용되었다. 연구결과를 요약하면 다음과 같다. 첫째, 소셜미디어 이용동기가 만족에 유의한 영향을 미치는 것으로 분석되었다. 둘째, 소셜미디어 이용만족이 재방문의도에 유의한 영향을 미치는 것으로 검증되었다. 본 연구결과를 토대로 소셜미디어 이용 동기가 농촌 체험마을 만족과 재방문의도에 영향을 미치는 결정요인들을 분석하여 농촌체험 이용고객의 만족과 재방문을 유도할 수 있는 다양한 전략적 시사점을 제시하였다.

QFP 솔더접합부의 크립특성에 관한 연구 (A Study on the Creep Characteristics of QFP Solder Joints)

  • 조윤성;최명기;김종민;이성혁;신영의
    • 한국공작기계학회논문집
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    • 제16권5호
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    • pp.151-156
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    • 2007
  • In this paper, the creep characteristics of lead and lead-free solder joint were investigated using the QFP(Quad Flat Package) creep test. Two kind of solder pastes(Sn-3Ag-0.5Cu, Sn-0.2Sb-0.4Ag-37.4Pb) were applied to the QFP solder joints and each specimen was checked the external and internal failures(i.e., wetting failure, void, pin hole, poor-heel fillet) by digital microscope and X-ray inspection. The creep test was conducted at the temperatures of $100^{\circ}C$ and $130^{\circ}C$ under the load of 15$\sim$20% of average pull strength in solder joints. The creep characteristics of each solder joints were compared using the creep strain-time curve and creep strain rate-stress curves. Through the comparison, the Sn-3Ag-0.5Cu solder joints have higher creep resistance than that of Sn-0.3Sb-0.4Ag-37.4Pb. Also, the grain boundary sliding in the fracture surface and the necking of solder joint were observed by FE-SEM.

적분형 최적 레귤레이터 적용 시스템 히트펌프 제어 시뮬레이션 연구 (Numerical Simulation of a System Heat Pump Adopting an Integral Optimum Regulating Controller)

  • 김용찬;최종민
    • 설비공학논문집
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    • 제25권7호
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    • pp.398-405
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    • 2013
  • Small and medium-size buildings employ a multi-distributed individual air-conditioning system that utilizes package air conditioners instead of centralized cooling systems, which can allow easier building management and maintenance, along with a diversification of facility use. Inverter driven system heat pumps have been developed to achieve not only an easy distribution control, allowing free combination of indoor units with different models and different capacities, but also wide applications to intelligent air conditioning. However, the control algorithms of the system heat pump are limited in the open literature, due to complicated operating conditions. In this paper, an inverter-driven system heat pump having two indoor units with electronic expansion valves (EEV) was simulated in the cooling mode. An integral optimum regulating controller employing the state space control method was also simulated, and applied to the system-heat pump system, to obtain efficient control of the MIMO (multi input multi output) system. The simulation model for the controller yielded satisfactory prediction results. The new control model can be successfully utilized as a basic tool in controller design.

ANALYSIS OF DOPPLER-BROADENED PEAK IN THERMAL NEUTRON INDUCED 10B(n,α γ)7Li REACTION USING HYPERGAM

  • Choi, Hee-Dong;Jung, Nam-Suk;Park, Byung-Gun
    • Nuclear Engineering and Technology
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    • 제41권1호
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    • pp.113-124
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    • 2009
  • The line shape functions for the Doppler-broadened gamma ray spectrum are considered in the $^{10}B(n,{\alpha}{\gamma})^7Li$ reaction occurring in a surrounding medium where the excited $^7Li$ nucleus is slowed down and stopped before decay. The phenomenological form of the stopping power was used for the broadening effect. Convolution with the detailed response of a germanium detector is taken into consideration for the simplest case of solely electronic stopping. A numerical study for the analysis of $^{10}B$ by thermal neutron capture is conducted by performing a parametric search and fitting the measured spectrum in a least-squares approach. In comparison with the previous numerical approach using the same analysis, the computational speed is increased and reliable information concerning the stopping power of the medium is obtained while estimating the uncertainty. Implementation of the routine analysis of $^{10}B$ is facilitated on a recent version of the gamma ray spectrum analysis package HyperGam.