• Title/Summary/Keyword: 사용 한계 상태

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Selective Area Epitaxy of GaAs and InGaAs by Ultrahigh Vacuum Chemical vapor Deposition(UHVCVD) (Ultrahigh Vacuum Chemical Vapor Deposition (UHVCVD)법에 의한 GaAs와 InGaAs 박막의 선택 에피택시)

  • 김성복
    • Journal of the Korean Vacuum Society
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    • v.4 no.3
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    • pp.275-282
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    • 1995
  • III족 원료 가스로 triethylgallium(TEGa)과 trimethylindium(TMIn)을 사용하고 V족 원료 가스로 사전 열 분해하지 않은 arsine(AsH3)과 monoethylarsine(MEAs)을 사용하여 ultrahigh vacuum chemical vapor deposition(UHVCVD)법으로 Si3N4로 패턴된 GaAs(100)기판 위에 GaAs와 InGaAsqkr막을 선택적으로 에피택시 성장을 하였다. V족 원료 가스를 사전 열 분해하지 않으므로 넓은 성장 온도 구간과 V/lll 비율에서도 선택적으로 박막이 성장되었다. 또한 선택 에피택시의 성장 메카니즘을 규명하기 위하여 다양한 filling factor(전체면적중 opening된 면적의 비율)를 가지는 기판을 제작하여 성장에 사용하였다. UHVCVD법에서는 마스크에 면적중 opening된 면적의 비율)를 가지는 기판을 제작하여 성장에 사용하였다. UHVCVD법에서는 마스크에 입사된 분자 상태의 원료 기체가 탈착된 후 표면 이동이나 가스 상태의 확산과정 없이 마스크로부터 제거되므로 패턴의 크기와 모양에 따른 성장 속도의 변화나 조성의 변화가 없을 뿐만 아니라 chemical beam epitaxy(CBE)/metalorganic molecular beam epitaxy(MOMBE)법에서 알려진 한계 성장온도 이하에서 선택 에피택시 성장이 이루어졌다.

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Deflection Calculation Based on Stress-Strain Curve for Concrete in RC Members (콘크리트 응력-변형률 관계에 기반한 철근콘크리트 부재의 처짐 산정)

  • Choi, Seung-Won;Kim, Woo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.4A
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    • pp.383-389
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    • 2010
  • The concrete structural design provisions in Korea are based on ultimate strength design. Up to service load stage, it is assumed a linear stress-strain relation, but there is no stress-strain relationship for a concrete material from service load stage to limat state. According to the current provisions, an independent method is provided for the each calculation of deflection and crack width. In EC2 provisions based on limit state design, however, a stress-strain relationship of concrete is provided. Thereby, it is able to calculate a strength as well as a deflection directly from concrete stress-strain relationship. In this paper the moment-curvature relationship is directly calculated from a material law using equilibrium and compatibility conditions. Then strength and deflection are formulated. These results are compared with the values from the current provisions in Korea. From the results, the deflection based on a moment-curvature relationship is well agreed with experimental results and it is appeared that the deflection after the yielding of steel is also possible.

Limit State Evaluation of Elbow Components Connected with Flexible Groove Joints (유동식 그루브 조인트로 연결된 엘보 요소의 한계상태 평가)

  • Sung-Wan Kim;Da-Woon Yun;Bub-Gyu Jeon;Dong-Uk Park;Sung-Jin Chang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.3
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    • pp.91-99
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    • 2024
  • Piping systems are crucial facilities used in various industries, particularly in areas related to daily life and safety. Piping systems are fixed to the main structures of buildings and facilities but do not support external loads and serve as non-structural elements performing specific functions. Piping systems are affected by relative displacements owing to phase differences arising from different behaviors between two support points under seismic loads; this can cause damage owing to the displacement-dominant cyclic behavior. Fittings and joints in piping systems are representative elements that are vulnerable to seismic loads. To evaluate the seismic performance and limit states of fittings and joints in piping systems, a high-stroke actuator is required to simulate relative displacements. However, this is challenging because only few facilities can conduct these experiments. Therefore, element-level experiments are required to evaluate the seismic performance and limit states of piping systems connected by fittings and joints. This study proposed a method to evaluate the seismic performance of an elbow specimen that includes fittings and joints that are vulnerable to seismic loads in vertical piping systems. The elbow specimen was created by connecting straight pipes to both ends of a 90° pipe elbow using flexible groove joints. The seismic performance of the elbow specimen was evaluated using a cyclic loading protocol based on deformation angles. To determine the margin of the evaluated seismic performance, the limit states were assessed by applying cyclic loading with a constant amplitude.

Driver Drowsiness Detection Model using Image and PPG data Based on Multimodal Deep Learning (이미지와 PPG 데이터를 사용한 멀티모달 딥 러닝 기반의 운전자 졸음 감지 모델)

  • Choi, Hyung-Tak;Back, Moon-Ki;Kang, Jae-Sik;Yoon, Seung-Won;Lee, Kyu-Chul
    • Database Research
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    • v.34 no.3
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    • pp.45-57
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    • 2018
  • The drowsiness that occurs in the driving is a very dangerous driver condition that can be directly linked to a major accident. In order to prevent drowsiness, there are traditional drowsiness detection methods to grasp the driver's condition, but there is a limit to the generalized driver's condition recognition that reflects the individual characteristics of drivers. In recent years, deep learning based state recognition studies have been proposed to recognize drivers' condition. Deep learning has the advantage of extracting features from a non-human machine and deriving a more generalized recognition model. In this study, we propose a more accurate state recognition model than the existing deep learning method by learning image and PPG at the same time to grasp driver's condition. This paper confirms the effect of driver's image and PPG data on drowsiness detection and experiment to see if it improves the performance of learning model when used together. We confirmed the accuracy improvement of around 3% when using image and PPG together than using image alone. In addition, the multimodal deep learning based model that classifies the driver's condition into three categories showed a classification accuracy of 96%.

Development of Numerical Analysis and Optimization AIgorithms for Orthotropic Continuous Curved Floor Slab Systems (이방성 연속 곡평면 슬래브 시스템의 수치해석과 최적화 알고리즘의 개발)

  • Park, Moon Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.12 no.3
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    • pp.1-15
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    • 1992
  • A Practical and easily applicable methods for the numerical analysis and the optimum design of continuous and horizontally curved two-way slab systems with twelve possible edge conditions are presented. The proposed method for the numerical structural analysis is based on the use of design moment coefficients which are derived from the elastic theory of thin curved plates. The optimum values are selected from within the feasible region in the design space defined by the limit state requirements. The sequential linear programming is introduced as an analytical method of nonlinear optimization. The optimum design variables, including a effective depth and transformed steel ratios per unit width of middle and column strips of slabs, are then determined.

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Reliability Analysis of Pile Type Quaywall Using Response Surface Method (응답면 기법을 이용한 잔교식 안벽의 신뢰성 해석)

  • Lee, Sang-Geun;Kim, Dong-Hyawn
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.6
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    • pp.407-413
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    • 2011
  • Reliability analysis of pile type quaywalls were done by using response surface method. Pier structures have implicit form of limit state function since they are flexible in motion, which is different from gravity type quaywalls. To solve a reliability analysis problem with implicit limit state function, response surface method was applied. Reliability indices of structure under seismic load were found for pier structures Then, they were compared with those found by simulation method. In numerical analysis, both the inclined type and vertical type were analyzed.

Measurement and Aalysis of Insulation Defects of Cast-resin Transformer on live wire state (활선상태에서 몰드변압기의 절연결함 측정기법 연구)

  • Choi, Myeong-Il;Lim, Young-Bae;Lee, Saing-Ik;Kim, Dong-Woo;Moon, Hyun-uk
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1569-1570
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    • 2015
  • 몰드변압기는 유입변압기와 달리 구조적으로 복잡하고 밀폐된 구조로 되어 있어서 사용기간 동안 고신뢰성을 확보하기 위해서 예방진단기술이 필요하다. 그러나 공장이나 빌딩 현장에서 몰드변압기의 열화상태 관리하는 방법은 온도관리, 소음진동관리 등의 수준으로 활선상태에서 사고를 예측하기에는 많은 한계가 있다. 이러한 문제점을 해결하고자 본 논문에서는 몰드변압기의 부분방전 측정을 중심으로 활선상태에서 열화 진단기술이 중요하다. 특히, 몰드변압기의 절연열화 진단을 위해서 상호보완적인 측정방법이 필요하고, 몰드변압기의 절연상태의 유무를 판정할 수 있는 분석방법을 개발하고자 하였다.

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The Study of continuous cardiac output measurement module development of the cardiopulmonary function patient of using the Swan-Ganz Catheter (Swan-Ganz 카테터를 이용한 심폐기능 이상 환자의 지속적 심박출량 측정 모듈 개발)

  • Lim, Byeong-Seon;Han, Seung-Hwan;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.4
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    • pp.959-964
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    • 2013
  • This study materialized the new module which enables to measure more precise data than the existing modules in order to examine the cardiac disorder critical patient's state by using Swan-Ganz Catheter. There was bolus type CO(Cardiac Output) module which measured CO by measuring the blood changes in temperature and recovery time by injecting cold sap into the heart in the past, but recently, it is not used in most of hospitals due to limit of difficulty of continuous monitoring for the patients. To overcome this limit, the continuous cardiac output measurement platform was materialized to enable the continuous monitoring for patients. The wasted cost issues because of introducing the expensive imported equipment to observe the critical patient`s state with abnormal cardiopulmonary function in the hospitals can be solved by using this new module, and the problem of existing modules should be supplemented for more accurate diagnosis by collecting more precise data.

A Dynamic Server Load Balancing based on Power Information for Saving Energy in a Server Cluster Environment (서버 클러스터 환경에서 에너지 절약을 위한 전력 정보 기반의 동적 서버 부하분산)

  • Kim, Dong-Jun;Kang, Na-Myong;Kwon, Hui-Ung;Kwak, Hu-Keun;Kim, Young-Jong;Chung, Kyu-Sik
    • Proceedings of the Korea Information Processing Society Conference
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    • 2011.04a
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    • pp.171-174
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    • 2011
  • 서버 클러스터에서 부하 분산기는 사용자의 요청을 각 서버로 분산시키는 역할을 한다. 리눅스 가상 서버(LVS: Linux Virtual Server)는 소프트웨어적으로 사용되는 부하 분산기로서 여러 가지 스케줄링 방식들을 가지고 있다. 그러나 부하 분산 시에 서버의 유동적인 부하 정보를 반영하지 못하는 단점이 있다. 이에 개선된 방식으로 서버의 동시 연결 개수에 따라 상한계(Upper Bound)와 하한계(Lower Bound)를 설정하고, 요청을 분산하는 동적 스케줄링(Dynamic Scheduling)이 존재한다. 그러나 서버의 상태에 따라 상한계와 하한계가 바뀔 수 있음에도 불구하고 이 값들이 고정되어 있다는 단점을 가진다. 본 논문에서는 기존 부하 분산 방법의 단점을 극복하는 서버 전력 정보에 기반한 스케줄링 방식을 제안한다. 제안된 방식은 서버의 부하 정보를 기반으로 에너지를 추정하고 전력 수치를 기반으로 LVS의 가중치 테이블을 주기적으로 갱신한다. 그리고 부하 분산기는 클라이언트로부터 요청 받은 트래픽을 각 서버의 에너지 소모 상태에 따라 적용시킴으로써 에너지 소모가 최소화되도록 부하를 분산한다. 또한 서버의 상태에 따라 상한계와 하한계가 바뀔수 있음을 고려하여 상한계와 하한계를 설정하지 않고 서버의 상태에 따라 적절하게 요청이 분배되도록 하였다. 15대의 PC를 사용하여 실험을 수행하였으며, 실험 결과는 기존 부하 분산 알고리즘 중 성능이 가장 좋은 알고리즘에 비해 서버의 성능이 동일한 경우 성능 및 소비전력 면에서 거의 동등하였고, 서버의 성능이 상이한 경우 50.2% 성능 향상 및 27.3% 소비 전력 절감을 확인하였다.

Assessment of Partial Safety Factors for Limit States Design of Foundations (한계상태설계법의 기초설계 적용을 위한 부분안전계수의 평가)

  • Kim Bum-Joo
    • Journal of the Korean Geotechnical Society
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    • v.20 no.9
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    • pp.77-89
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    • 2004
  • While limit states design (LSD) is currently the standard structural design practice, it is relatively new in the geotechnical design. Adoption of LSD far geotechnical design is an international trend. In the present study, various LSD codes from the United States, Canada, and Europe were reviewed. A simple first-order-second-moment (FOSM) reliability analysis was performed to determine theoretically the ranges of load and resistance factor values for representative loads and foundation bearing capacity, respectively. In order for foundation design to be consistent with current structural design practice, it would be desirable to use the same loads, load factors and load combinations. The values of load factor, obtained from the FOSM analysis, were found to be generally consistent with those given in the codes, whereas the values of resistance factor indicated overall lower ranges due to high values of coefficient of variation used in the analysis. Since the degree of uncertainties included in bearing capacity of foundations varies with the methods used to estimate the bearing capacity, different values of resistance factor should be used fur different methods. For the purpose, continuous efforts are needed to be made first to accurately identify and quantify the uncertainties in the methods.