• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.153-164
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• 1998

본 논문은 2-상태 시스템의 신뢰도 계산을 위하여 Heidtmann[3]이 제시한 가역 알고리즘을 부울 대수를 사용하여 경로집합으로부터 절단집합을 유도하거나, 역으로 절단집합으로부터 경로집합을 유도함으로서 효율성을 입증하였으며, 포함-불포함 공식(inclusion-exclusion formula)과 추축 분해법칙(pivotal decomposition rule)을 이용하여 직·병렬구조 및 복합구조의 신뢰도를 계산할 수 있는 알고리즘을 개발, 분석하였다.

• Electrical & Electronic Materials
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• v.17 no.6
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• pp.11-16
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• 2004

지난 40여년간의 반도체 집적 공정의 발전에 있어서 무어(Moore)의 법칙에 의한 소자의 미세화를 달성하기 위하여, 광리소그래피(optical lithography) 기술은 꾸준히 발전하여 왔으며, 소자의 선폭이 나노스케일인 공정에서 역시, 소자 제조의 핵심기술은 리소그래피 기술을 이용한 회로의 패터닝(patterning) 기술에 달려 있다고 해도 과언이 아니다. 그러나 현재 사용되고 있는 광리소그래피는 사용하는 파장의 길이에 따른 분해능(resolution)의 한계로 인하여, 이러한 나노 스케일의 소자를 제작하기 위해서는 새로운 리소그래피 기술이 필요하다는 것이 일반적으로 인정이되고 있다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.29-39
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• 1999

Many industrial products can be assembled in various sequences of assembly operations. To save time and cost in assembly process and to increase the quality of products, it is very important to choose an optimal assembly sequence. In this paper, we propose a methodology that generates an optimal assembly sequence by using the knowledge of experts. First, a product is divided into several sub-assemblies. Next, the disassembly sequences of sub-assembly are generated using disassembly rules and special information can be extracted through the disassembly process. By combining every assembly sequence of sub-assemblies, we can generate all the possible assembly sequences of a product. Finally, the expert system evaluates all the possible assembly sequences and finds an optimal assembly sequence. It can be achieved under consideration of the parameters such as assembly operation, tool change, safety of part. basepart location, setup change, distance, and orientation. The developed system is applied to UBR(Unit Bath Room) example.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.501-513
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• 1987

Conditions for achieving noninteraction in nonlinear multivariable systems via the decomposition of state space are well established. The main contribution of this paper is to fully characterize the class of decomposing control laws. The characterization corresponds to a family of simple control laws which are applied to a standard decomposed system(SDS). The SDS is similar to the decomposed systems of Isidori, Krener, Gori-Giorgi, and Monaco but has a finer structure. The finer structure parallels the one used by Gilbert for linear systems. A weaker form of noninteraction, based on input-output behaviour, is decoupling. Some connections between decomposition and decoupling are also established. An example illustrating the importance of the results is given.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.790-805
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• 1988

Static strength and fatigue life scattering of glass fiber reinforced epoxy composite materials has been studied. Normal, lognormal, two-parameter and three-parameter Weibull distribution functions are used for strength and one-stress fatigue life distribution. The value of mean fatigue life is analysed using mean fatigue life, mean log fatigue life and expected value of 2 and 3-parameter Weibull distribution functions. Modification on non-statistical cumulative damage models is made in order to interpret the result of two-stress level fatigue life scattering. The comparison results show that 3-parameter Weibull distribution has better predictions in static strength and one-stress level fatigue life distributions. However, no advantage of 3-parameter Weibll distribution is found over 2-parameter Weibull distribution in two-stress level fatigue life predictions. It is found that two-stress level fatigue life prediction by the expanded equal rank assumption is close to the experimental data.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.753-756
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• 1993

Studies on the molecular interactions of dimethylsulfoxide (DMSO) with water and/or some alkanols were carried out by vapor pressure osmometry at 40$^{\circ}C$. Negative deviation from Raoult's law was observed for the DMSO-water, methanol, ethanol, 1-propanol, 2-propanol, and 2-methyl-1-propanol systems, whereas positive deviation from Raoult's law was observed for the DMSO-1-butanol and 1-pentanol systems. The results were interpreted in terms of molecular interactions between unlike molecules, and of self-association of DMSO molecules, respectively. Measured chemical shift of hydroxyl proton of the solvents also supported the results.

• Fire Science and Engineering
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• v.32 no.1
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• pp.1-6
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• 2018

The flash point is one of the most important parameters used to characterize the ignition and explosion hazards of liquids. Flash points were measured for several binary systems containing toluene, including {methanol+toluene}, {ethanol+toluene}, and {1-propanol+toluene}. Experiments were performed according to the standard test method using a SETA closed cup flash point tester. The measured flash points were compared with the predicted values calculated using the following $G^E$ models: Wilson, NRTL, and UNIQUAC. The average absolute deviation between the predicted and measured lower flash point was less than 1.69 K.

• The Mathematical Education
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• v.58 no.3
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• pp.383-401
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• 2019

This study started with the idea that it is necessary to focus on common concepts and ideas among the subjects when conducting integrated education in high school. This is a preliminary study for developing materials that can be taught in mathematics in the context of already learning scientific concepts in high school. For this purpose, Mendel 's law of genetics was studied among the contents of biological subjects which are known to have relatively little connection with mathematics. The more common links between the two subjects are, the better, in order to integrate math and other subjects and develop materials for teaching. Therefore, in this study, we investigated not only the probability domain but also the concept of statistical domain. We have been wondering if there is a more abundant idea to connect between 'Mendel's law' and 'probability and statistics'. Through these anxieties, we could find that concepts such as 'likely equality' and 'permutation and combination' including 'a large number of laws' can be a link between two subjects. Based on this, we were able to develop class materials that correspond to classes. This study is expected to help with research related to development of integrated education support materials, focusing on mathematics.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.318-318
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• 2016

위성은 준 실시간으로 국토 전체의 관측과 미계측/비접근 지역의 관측도 가능하여 가뭄, 홍수 등 수재해와 관련된 분석 자료로 활용되고 있으며, 위성 기반의 수재해 모니터링 적용성에 대한 연구 또한 수행되고 있다. 위성에서 관측된 자료는 NASA, JAXA 등의 위성 관리 센터에서 알고리즘을 적용하여 인터넷으로 제공하고, 최근 K-water에서는 수자원분야의 위성활용을 위해 위성 자료 수집 시스템을 갖추어 Aqua/Terra MODIS, GPM, GCOM-W1 등의 위성 자료를 수집하고 있다. 위성 자료는 5분~16일 등의 다양한 주기로 제공되고 있으며, 자료 타입, 측정 시간 등의 간단한 정보만 파일명으로 표시되어 위성의 위치(경위도) 및 해당 지점의 위성 자료를 얻기 위해서는 위성 자료를 확인해야만 하는 번거로움이 따른다. 본 연구에서는 순차적으로 관측된 위성 자료의 시 공간적 속성정보를 추출하고 해당 정보를 영상과 함께 맵핑하여, 시간의 흐름에 따른 위성 궤도의 시각화 방안을 제시하였다. 위성 궤도의 시각화 방안으로 사용된 위성 자료는 Terra MODIS의 'MOD02SSH', GPM GMI 센서의 'GPROF' 자료 타입을 사용하였다. 'MOD02SSH'는 5분 동안 5km의 공간해상도로 측정한 자료가 1개의 파일이며, 'GPROF'는 5분 동안 4km의 공간해상도로 측정한다. 공전 주기의 검증을 위해 케플러의 제3법칙을 적용한 Terra 위성의 공전주기는 98.75분으로 계산되며, 위성 자료의 공전주기는 98.87분으로 나타난다. 검증 결과 약 0.12초의 오차가 발생하며, 정확한 위성 고도와 높은 해상도의 위성 자료를 통해 오차의 감소가 가능하다. 이를 통해 시각화 된 동적 시계열 이미지는 시간에 따른 위성 궤도의 정보를 추출 할 수 있다. 이는 수재해 정보시스템의 모니터링을 위해 사용 가능하고, 시간에 따른 위성 궤도 정보를 통하여 필요한 시간대의 위성 위치 정보, 해당 지점의 관측 자료를 효율적으로 수집하여 자료 수집을 위한 시간 단축이 가능하며, 사용자 또는 관리자를 위한 모니터링 수행 또한 효율적인 운영이 가능할 것으로 사료된다.

• Clean Technology
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• v.26 no.3
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• pp.161-167
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• 2020

For the design of the prevention and mitigation measures in process industries involving flammable substances, reliable safety data are required. An important property used to estimate the risk of fire and explosion for a flammable liquid is the flash point. Flammability is an important factor to consider when developing safe methods for storing and handling solids and liquids. In this study, the flash point data were measured for the binary systems {2-butanol + 2,2,4-trimethylpentane}, {2-butanol + methylcyclohexane} and {2-butanol + toluene} at 101.3 kPa. Experiments were performed according to the standard test method (ASTM D 3278) using a Stanhope-Seta closed cup flash point tester. A minimum flash point behavior was observed in the binary systems as in the many cases for the hydrocarbon and alcohol mixture that were observed. The measured flash points were compared with the predicted values calculated via the following activity coefficient (GE) models: Wilson, Non-Random Two-Liquid (NRTL), and UNIversal QUAsiChemical (UNIQUAC) models. The predicted data were only adequate for the data determined by the closed-cup test method and may not be appropriate for the data obtained from the open-cup test method because of its deviation from the vapor liquid equilibrium. The predicted results of this work can be used to design safe petrochemical processes, such as the identification of safe storage conditions for non-ideal solutions containing flammable components.