• Journal of Korean Society for Quality Management
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• v.25 no.1
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• pp.135-141
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• 1997

The Copper-Clad Laminate (CCL) is a main electronic component of specialtype printed circuit boards (PCBs) such as Silver Through Hole PCB. This CCL should have high reliability under the aging test, and usually the test is done at a higher temperature (110-$150^{\circ}C$) than the normal. Then, this test condition of high temperature may cause such quality problems as hole eccentricity and reduction of distance between part holes. After measuring the CCL shrinkage affected by temperature, the correction factor of a press mold was a, pp.ied to solve these problems. The results showed that the tolerance of hole pitch(${\pm}$$100{\mu}m$) was satisfactory and the internal and external failure costs were reduced by 55%.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.765-771
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• 1998

An artificial neural network(NN) technique is developed for hardware redundant sensor validation. Since the measurement space is a continuous space with many operating regions, it is difficult to train a NN to correctly detect failure in an accurate measurement system. A conventional backpropagation NN is modified to include an additional preprocessing layer that extracts classification features from scalar measurements. This feature extraction means transform the measurement space to parity space. The NN is independent of the state variable being measured, the instrument range, and the signal tolerance. This NN resembles the parity space approach to signal validation, except that analytical parity equations are unneeded and the NN pattern recognition capability is utilized for decision making.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1526-1532
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• 2014

The Electronic Interlocking unit in railway signalling system is safety-related facilities to determine route and speed for train running. In particular, the SSI(Solid State Interlocking) is Electronic Interlocking unit for high-speed railway, and it performs safety-critical function by MPM(Micro-Processor Module). Meanwhile, MPM is composed of the PES(Programmable Electronic System)-based system, and the PES-based system in railway safety-related facilities should be implemented by complying with the safety requirements defined in IEC 62425 and IEC 61508. In this paper, we performed modeling of failure rate and reliability for MPM implemented by fault tolerance methods and analyzed functional safety for MPM. Moreover, we determined SIL(Safety Integrity Level) for MPM according to the safety requirements defined in IEC 61508 based on an analyzed functional safety.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.83-88
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• 2015

At the early stages of engineering design, a number of design concepts may be suggested. With a great degree of freedom, making a good choice may be a challenge at this stage. In this study, a simplified evaluation criterion for design concepts is presented based on cost, simplicity and safety. Cost is estimated by the amount of materials and the required level of tolerance. Simplicity is represented by the number of parts, assembly steps, and fasteners. Safety is assessed by the level of potential failure. The proposed criterion is applied to an example design of driving mechanisms for cervical vertebrae massage machine.

• Journal of the Korea Construction Safety Engineering Association
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• s.54
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• pp.41-55
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• 2011

The current railway projects under plan, design, or construction have been designed as 'very long and deep underground tunnel'. Therefore, it is reasonable that the standards for preventing disaster in such conditions should be intensified in order to avoid repeating the same failure which happened in Daegu subway disaster, Although we consent to the opinion that nothing can compete with human being's life, it is very difficult to protect the life from all of potential disasters perfectly in railway fields because the excessive standards can result in excess construction cost, which can bring about cancelation of the project itself eventually. Therefore optimized disaster design standard is required to negotiate the conflict between economical cost and social tolerance limitation simultaneously.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2298-2300
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• 2002

In this paper, we introduced a fault tolerant control system with the aim of achieving higher degree of reliability for a PLC control system in the field network. The system reliability was evaluated by MTBF(Mean Time Between Failure). The design of the fault tolerant system through CC-Link of Mitsubisi's MELSEC network was presented. In addition, the PLC data is transmitted from the field network's PC to the host PC by TCP/IP Window socket.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.126-134
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• 2008

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires (steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive hybrid redundancy that can remove most erroneous values. In addition, several numerical simulation results are given where the predictive hybrid redundancy outperforms wellknown average and median voters.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.229-232
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• 2006

The HPFRCCs show that the multiple crack propagation, high tensile strength and ductility due to the interfacial bonding of the fibers to the cement matrix. Moreover, performance of cement composites varies according to type and weight contents of reinforcing fiber. and HPFRCCs with hybrid fiber have better performance than HPFRCCs with single fiber in damage tolerance. Total four cylindrical specimens were tested, and the main variables were the type and weight contents of fiber, which was polyvinylalchol (PVA), polyethylene (PE). In order to clarify effect of hybrid types on the characteristics of fracture and damage process in cement composites, AE method was performed to detect micro-cracking in HPFRCCs under cyclic compression. Loading conditions of the uniaxial compression test were monotonic and cyclic loading. And from AE parameter value, it is found that the second and third compressive load cycles resulted in successive decrease of the amplitude as compared with the first compressive load cvcle.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1155-1158
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• 2002

고리 및 영광 등 국내 원자력발전소의 디지털 방사선 감시계통(DRMS)는 이기종의 방사선 계측장치와 계측데이터 수집, 처리 장치의 혼합으로 구성되는 경우가 많아서 DRMS 가 갖추어야 될 계통 구성의 신축성과 운영편리성을 위하여 개선점이 많은 것으로 판단된다. Java 프로그래밍 언어를 확장하는 Jini 의 기술은 확장성(Scalability)과 건전성(Robustness), 이식성 (Portability), 그리고 원자력 발전소 계통 설계요건에서 가장 중요시되는 고장 대처능력 (Failure-tolerance)을 갖춘 DRMS 구성을 가능하게 한다. 본 논문은 Jini 기술을 이용하여 초기 및 운영 비용을 절감하면서도 효율성과 안전성을 증대시킬 수 있는 새로운 DRMS 구축방안을 제시한다.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.509-522
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• 2011

FRAPCON-3.4a and FRAPTRAN 1.4 are the most recent versions of the U.S. Nuclear Regulatory Commission (NRC) steady-state and transient fuel performance codes, respectively. These codes have been assessed against separate effects data and integral assessment data and have been determined to provide a best estimate calculation of fuel performance. Recent updates included in FRAPCON-3.4a include updated material properties models, models for new fuel and cladding types, cladding finite element analysis capability, and capability to perform uncertainty analyses and calculate upper tolerance limits for important outputs. Recent updates included in FRAPTRAN 1.4 include: material properties models that are consistent with FRAPCON-3.4a, cladding failure models that are applicable for loss-of coolant-accident and reactivity initiated accident modeling, and updated heat transfer models. This paper briefly describes these code updates and data assessments, highlighting the particularly important improvements and data assessments. This paper also discusses areas of improvements that will be addressed in upcoming code versions.