• 마이크로전자및패키징학회지
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• 제24권1호
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• pp.83-90
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• 2017

본 연구에서는 미세피치 패키지 적용을 위한 기초 실험으로 thin ENEPIG(Electroless Nickel Electroless Palladium Immersion Gold) 도금층을 형성하여 솔더링 특성을 평가하였다. 먼저, Sn-3.0Ag-0.5Cu (SAC305) 솔더합금에 대한 thin ENEPIG 도금층의 젖음 특성이 평가되었으며, 순차적인 솔더와의 반응에 대한 계면반응 및 솔더볼 접합 후 고속 전단 시험을 통한 접합부 기계적 신뢰성이 평가되었다. 젖음성 시험에서 침지 시간이 증가함에 따라 최대 젖음력은 증가하였으며, 5초의 침지 시간 이후에는 최대 젖음력이 일정하게 유지되었다. 초기 계면 반응 동안에는 $(Cu,Ni)_6Sn_5$ 금속간화합물과 P-rich Ni 층이 SAC305/ENEPIG 계면에서 관찰되었다. 연장된 계면반응 후에는 P-rich Ni 층이 파괴 되었으며, 파괴된 P-rich Ni 층 아래에는 $(Cu,Ni)_3Sn$ 금속간화합물이 생성되었다. 고속 전단 시험의 경우, 전단속도가 증가함에 따라 취성 파괴율이 증가하였다.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.43-49
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• 2019

본 연구에서는 그래핀 산화(graphene oxide, GO) 분말 복합 Sn-3.0Ag-0.5Cu(in wt.%) 솔더페이스트를 이용한 플렉시블 기판과 SOP(small outline package) 사이의 솔더 접합부의 굽힘 신뢰성 향상에 관한 새로운 접근을 제안하였다. 솔더페이스트에 GO의 첨가는 녹는점에 약간의 영향을 미치었으나 그 차이는 미미한 것으로 나타났다. 한편, GO의 첨가는 리플로우 공정 동안 솔더 접합부의 금속간화합물(intermetallic compound, IMC) 성장과 두께를 억제 할 수 있음을 확인하였다. 더욱이 접합부의 신뢰성에 미치는 영향을 살펴보고자 반복 굽힘 시험을 진행하였으며 GO 분말의 첨가로 솔더 접합부의 반복 굽힘 신뢰성 향상 시킬 수 있었다. 0.2 wt.%의 GO가 첨가된 솔더 접합부의 경우 GO가 첨가되지 않은 경우에 비하여 굽힘 수명은 20% 가량 증가하는 것으로 나타났다. GO가 첨가된 경우 솔더 접합부의 인장 강도와 연성이 증가하게 나타났는데 이러한 GO 첨가에 의한 기계적 특성 향상이 솔더 접합부의 반복 굽힘 신뢰성 향상에 기여한 것으로 추측된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.808-810
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• 2002

Higher current-rating and improved thermal performance are being sought for existing medium-voltage vacuum circuit breakers(VCB) in order to meet market needs which require to be compact and downsized. In this paper, thermal performance of medium voltage vacuum circuit breaker was investigated through experiments and numerical analysis. We changed several major parameters of current-rating and heat sink affecting on thermal behaviors in the breaker and observed the results. To predict the temperature distribution in complex three-dimensional (3-D) VCB components and gas, the commercial package was used to simulate conjugate heat transfer. Although some assumptions and simplifications were introduced to simulate the model, results from the computational model were in good agreement with actual temperature rise measurements obtained from experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.39-42
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• 2002

In this study, the computational heat transfer of the high-voltage vacuum circuit breaker was investigated. Higher normal current-ratings and stabilized thermal characteristics become more important in existing circuit breakers in order to satisfy market needs. Increases in current-ratings have an even greater effect on the Joule heating in the main circuit of the breakers. The thermal design must account for this increase in heat produced for the breaker to meet various temperature-rise limits set by industry standards. We are studying to enhance the normal current-ratings without major frame change of our present production models. As the method used in this research, we performed the computational analysis using the commercial Package, ICEPAK. We could get optimized thermal design suitable for 25% upgraded normal current-ratings through parametric study.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.445-446
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• 2007

The use of plastic substrates enables new applications, such as flexible display devices, and other flexible electronic devices, using low cost, rollto-roll (R2R) fabrication technologies. One of the limitations of polymeric substrate in these applications is that oxygen and moisture rapidly diffuse through the material and subsequently degrade the electro-optical devices. GE Global Research (GEGR) has developed a plastic substrate technology comprised of a superior high-heat polycarbonate (LEXAN(R)) substrate film and a unique transparent coating package that provides the ultrahigh barrier (UHB) to moisture and oxygen, chemical resistance to solvents used in device fabrications, and a high performance transparent conductor. This article describes the coating solutions for polycarbonate (LEXAN(R)) films and its compatibility with OLED device fabrication processes.

• 천문학회보
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• 제39권1호
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• pp.54.2-54.2
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• 2014

IGRINS (Immersion GRating Infrared Spectrograph) is a high spectral resolution near-infrared spectrograph that has been developed in a collaboration between the Korea Astronomy & Space Science Institute and the University of Texas at Austin. By using a silicon immersion echelle grating, the size of the fore optics is reduced by a factor of three times and we can make a more compact instrument. One exposure covers the whole of the H- and K-band spectrum with R=40,000. While the operation of and data reduction for this instrument is relatively simple compared to other grating spectrographs, we still need to operate three infrared arrays, cryostat sensors, calibration lamp units, and the telescope during astronomical observations. The IGRINS Instrument Control Software consists of a Housekeeping Package (HKP), Slit Camera Package (SCP), Data Taking Package (DTP), and Quick Look Package (QLP). The SCP will do auto guiding using a center finding algorithm. The DTP will take the echellogram images of the H and K bands, and the QLP will confirm fast processing of data. We will have a commissioning observations in 2014 March. In this poster, we present the performance of the software during the test observations.

• 대한원격탐사학회지
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• 제34권1호
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• pp.89-99
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• 2018

Spatial downscaling is often applied to coarse scale satellite products with high temporal resolution for environmental monitoring at a finer scale. An area-to-point regression kriging (ATPRK) algorithm is regarded as effective in that it combines regression modeling and residual correction with area-to-point kriging. However, an open source tool or package for ATPRK has not yet been developed. This paper describes the development and code organization of an R-based spatial downscaling tool, named R4ATPRK, for the implementation of ATPRK. R4ATPRK was developed using the R language and several R packages. A look-up table search and batch processing for computation of ATP kriging weights are employed to improve computational efficiency. An experiment on spatial downscaling of coarse scale land surface temperature products demonstrated that this tool could generate downscaling results in which overall variations in input coarse scale data were preserved and local details were also well captured. If computational efficiency can be further improved, and the tool is extended to include certain advanced procedures, R4ATPRK would be an effective tool for spatial downscaling of coarse scale satellite products.

• 한국컴퓨터정보학회논문지
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• 제22권1호
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• pp.49-56
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• 2017

In this paper we propose the approach for big data integration so as to analyze, visualize and predict the future of the trend of the market, and that is to get the integration data model using the R language which is the future of the statistics and the Hadoop which is a parallel processing for the data. As four approaching methods using R and Hadoop, ff package in R, R and Streaming as Hadoop utility, and Rhipe and RHadoop as R and Hadoop interface packages are used, and the strength and weakness of four methods are described and analyzed, so Rhipe and RHadoop are proposed as a complete set of data integration model. The integration of R, which is popular for processing statistical algorithm and Hadoop contains Distributed File System and resource management platform and can implement the MapReduce programming model gives us a new environment where in R code can be written and deployed in Hadoop without any data movement. This model allows us to predictive analysis with high performance and deep understand over the big data.

• 한국세라믹학회지
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• 제53권3호
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• pp.263-272
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• 2016

Electronic structure calculations have become a powerful foundation for computational materials engineering. Four major factors have enabled this unprecedented evolution, namely (i) the development of density functional theory (DFT), (ii) the creation of highly efficient computer programs to solve the Kohn-Sham equations, (iii) the integration of these programs into productivity-oriented computational environments, and (iv) the phenomenal increase of computing power. In this context, we describe recent applications of the Vienna Ab-initio Simulation Package (VASP) within the MedeA$^{(R)}$ computational environment, which provides interoperability with a comprehensive range of modeling and simulation tools. The focus is on technological applications including microelectronic materials, Li-ion batteries, high-performance ceramics, silicon carbide, and Zr alloys for nuclear power generation. A discussion of current trends including high-throughput calculations concludes this article.

• 한국정밀공학회지
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• 제33권6호
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• pp.431-438
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• 2016

Recently, concerns about the environment are becoming more important because of global warming and the exhaustion of earth's resources. In the aviation and automobile industries, the application of light materials is increasingly important for eco-friendly and effective. Carbon Fiber Reinforced Plastics is a composite material which great formability and the high strength of carbon fiber. CFRP, which is both light and strong, is hard to manufacture. In addition, CFRP machining has a high chance of defects. This research discusses the development of a manufacturing system package for CFRP machining. It involving CFRP Drilling/Water-jet Manufacturing Machines, Inspection/Post-processing Systems, CNC platform for an EtherCAT servo Communication, Flexible Manufacturing Systems and CFRP machining Processes.