• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.148-158
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• 1991

The Built-In-Test (BIT) system is an integrated subsystem for the determination of the health status of any primary system. The BIT consists of hardware and software installations directed at performance of the functions of fault detection, diagnosis and isolation, as well as primary system record failure information. Evaluation of the difinitions appropriate to the BIT system, including system characteristics and parameters, is important to an understanding of system functions. The object of this paper is to present general definitions of the BIT diagnosis parameters and a semiquantiative evaluation method for BIT systems. Finally, two case studies for actual problem solutions are included.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.2
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• pp.183-194
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• 1995

This research paper describes several possible suggestions which are essential to develop for Built-In-Test(BIT) related systems, such as more precise BIT parameter analysis, sensitivity analysis of the impact of BIT on redundant systems, statistical inference of field data for BIT performance parameters, methods of reducing BIT false alarms, BIT application in industrial automation and remote control, prevent the system from the impact of BIT failure, undetections and false alarms, life cycle cost analysis for BIT. And, it is mainly focused on redundancy technique for solving BIT diagnostic problems. Algorithms for redundant systems : overlapping technique, flexible redundant BITs are presented and case study will be shown based on various experiment.

• Computers and Concrete
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• v.20 no.5
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• pp.617-625
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• 2017

Prestress force identification (PFI) is crucial to maintain the safety of prestressed concrete bridges. A synergic identification method has been proposed recently by the authors that can determine the prestress force (PF) and the excitation force simultaneously in prestressed concrete beams with good accuracy. In this paper, the ability of this method in the application with prestressed concrete box-girder bridges is demonstrated. A reasonable assumption is made to capture the similarity of the dynamic behavior of the prestressed concrete box-girder bridge and a beam under a certain loading scenario, and the feasibility of this method for application in a prestressed box-girder bridge is affirmed. A comprehensive laboratory test program is conducted, and the effects of PF, excitation, measuring time and uncertainties are studied. Results show that the proposed method can predict the PF and the excitation force in a prestressed concrete box-girder accurately and has a great robustness against uncertainties.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.499-511
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• 2019

In this study, the axial compressive behavior of novel quadruple C-channel built-up cold-formed steel columns with different slenderness ratio was investigated, using the experimental and numerical analysis. The axial compressive capacity and failure modes of the columns were obtained and analyzed. The finite element models considering the geometry, material and contact nonlinearity were developed to simulate and analyze the structural behavior of the columns further. There was a great correlation between the numerical analyses and test results, which indicated that the finite element model was reasonable and accurate. Then influence of, slenderness ratio, flange width-to-thickness ratio and screw spacing on the mechanical behavior of the columns were studied, respectively. The tests and numerical results show that due to small slenderness ratio, the failure modes of the specimens are generally local buckling and distortional buckling. The axial compressive strength and stiffness of the quadruple C-channel built-up cold-formed steel columns decrease with the increase of maximum slenderness ratio. When the screw spacing is ranging from 150mm to 450mm, the axial compressive strength and stiffness of the quadruple C-channel built-up cold-formed steel columns change little. The axial compressive capacity of quadruple C-channel built-up cold-formed steel columns increases with the decrease of flange width-thickness ratio. A modified effective length factor is proposed to quantify the axial compressive capacity of the quadruple C-channel built-up cold-formed steel columns with U-shaped track in the ends.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.177-187
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• 2016

To evaluate the tractive performance of tracked trencher on seafloor surface, a new shear stress-displacement empirical model was proposed for saturated soft-plastic soil (SSP model). To validate the SSP model, a test platform, where track segment shear test can be performed in seafloor soil simulacrum (bentonite water mixture), was built. Series shear tests were carried out. Test results indicate that the SSP model can describe the mechanical behavior of track segment with good approximation in seafloor soil simulacrum. Through analyzing the main external forces applied to seafloor tracked trencher during the uniform linear trenching process, a drawbar pull prediction model was deduced with the SSP model. A tracked walking mechanism of the seafloor tracked trencher prototype was built, and verification tests were carried out. Test results indicate that this prediction model was feasible and effective; moreover, from another side, this conclusion also proved that the SSP model was effective.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.713-715
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• 2012

본 논문은 24GHz 차량 추돌 예방 레이더 시스템-온-칩을 위한 입력 임피던스, 전압이득 및 잡음지수를 자동으로 측정할 수 있는 새로운 형태의 고주파 자체 내부검사(BIST, Built-In Self-Test) 회로를 제안한다. 이러한 BIST 회로는 TSMC $0.13{\mu}m$ 혼성신호/고주파 CMOS 공정 ($f_T/f_{MAX}$=140/120GHz)으로 설계되어 있다. 알고리즘은 LabVIEW로 구현되어 있다. BIST 알고리즘은 입력 임피던스 정합과 출력 직류 전압 측정원리를 이용한다. 본 논문에서 제안하는 방법은 자동으로 쉽게 고주파 회로의 성능변수를 측정할 수 있기 때문에 시스템-온-칩의 저가 성능 검사의 대안이 될 것으로 기대한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.605-614
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• 1992

초기단계의 제품 검사방법은 단순히 제품이 제대로의 기능을 수행하는지 안하는지에 대해서만 검사하고 결정을 내릴 뿐이었다. 대부분의 검사란, 검사자에게 최종적으로 제품이 인수된 후에 제품의 상태여부를 한정적이고, 제한적으로만 판단하여 검사결과를 제공하여왔다. 현대의 제품특성이 구조적 복잡성의 증가, 제품불량 현상파악의 난이도 증가등으로 제품의 사용절차, 검사, 유지보수, 부품교환등이 점점 더 난해해지고, 검사자의 개인적인 숙련도도 증가하게 되어, 제품을 유지보수하는데 더 많은 비용과 시간을 필요로하게 되었다. 이러한 문제들의 해결방안의 하나로 제품의 자체에 스스로 검사할 수 있는 체계적인 시스템을 설치하게 되어 BIT(Built-In-Test)가 탄생하게 되었다. BIT는 현존하는 제품뿐만아니라, 생산될 제품의 설계단계에서도 많이 응용되어 제품의 RAM(Reliability, Availability, Maintainability)에 많은 기여를 해왔다. 이 PAPER는 지금까지 BIT가 주로 Military System에 적용되어온 것을 Commercial system으로의 변환을 위한 기초작업을 제시하고 여러 대안을 열거하였으며, BIT가 갖고 있는 문제점들을 파악하여, 향후 고도화 되가는 산업사회의 요구에 부응할 수 있는 토대를 마련코자 Survey하였다.

• Architectural research
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• v.14 no.1
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• pp.3-9
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• 2012

Owing to the advent of ubiquitous computing technologies, the concept of Intelligent Environments has emerged, as an alternative approach to overcome the limitation of the built environment. Intelligent Environments can be more responsive to user-and context-specific human activities by automatically and dynamically modifying their settings without explicit human intervention. However, the conventional approach to the development of Intelligent Environments has mainly focused on the technical issues without paying much attention to the dynamic interrelationship between the user and the built environment. Therefore, differing or conflicting needs of multiple simultaneous users remain unresolved. The objective of this study is to present types of environmental conflicts and their resolution through agent collaboration and negotiation. For the demonstration and validation of the conflict resolution process, a set of hypothetical test cases is simulated in a 3D test environment. The result of the case simulations shows that the proposed approach is computationally feasible and applicable to the development of Intelligent Environments, and, furthermore, it can overcome the drawback of the conventional approach.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.935-938
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• 1999

메모리 테스트는 Built-In Self Test(BIST)와 같이 메모리에 내장된 회로를 통하여 자체 점검하는 방법과 테스터를 통하여 생성된 패턴을 주입하는 방법이 있다. 테스트 패턴 생성방법으로는 각각의 고장모델에 대한 테스트 패턴을 deterministic하게 생성해주는 방법과 Pseudo Random Pattern Generator(PRPG)를 이용하여 생성하는 경우로 구분할 수 있다. 본 연구에서는 PRPG를 패턴 생성기로 사용하여 여러 가지 메모리의 결함을 대표한다고 볼 수 있는 Static 및 Dynamic Neighborhood Pattern Sensitive Fault(NPSF) 등 다양한 종류의 고장을 점검할 수 있도록 메모리 BIST를 구성하였다. 기존의 Linear Feedback Shift Register(LFSR)보다 본 연구에서 제안하는 Linear Hybrid Cellular Automata(LHCA)를 이용한 PRPG가 높고 안정된 고장 점검도를 나타내었다.