• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2836-2838
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• 1999

고신뢰도의 요구를 보장하는 병렬 구조의 분산시스템의 사용이 증가함에 따라 네트워크 상에서 메시지전달을 방해하는 요소고장의 영향을 최소화시킬 수 있는 고장포용 라우팅에 대한 중요성이 부각되고 있다. 그러나, 네트워크의 복잡한 환경 때문에 요소고장을 극복하기 위한 고장포용 라우팅 알고리즘의 설계는 쉬운 일이 아니다. 본 논문에서는 2차원 메쉬 네트워크에 적용되는 최적의 고장포용 라우팅 알고리즘을 설계하기 위하여 관련 응용분야에서 그 유용성이 검증된 유전 알고리즘을 이용한다. 제안된 알고리즘은 wormhole 라우팅 방식을 사용하며, 교착상태를 없애기 위하여 하나의 물리적 채널을 공유하는 4개의 가상채널을 사용한다. 마지막으로, 시뮬레이션을 통하여 제안된 알고리즘이 기존의 다른 고장포용 라우팅 알고리즘보다 우수함을 증명한다.

• Korean Journal of Metals and Materials
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• v.47 no.8
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• pp.500-507
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• 2009

Pb-free solder has recently been used in electronics in efforts to meet environmental regulations, and a number of Pb-free solder alloy choices beyond the near-eutectic SnAgCu solder are now available. With increased demand for thin and portable electronics, the high cost of alloys containing significant amounts of silver and their poor mechanical shock performance have spurred the development of low Ag SnAgCu solder, which provides improved mechanical performance at a reasonable cost. Although low Ag SnAgCu solder exhibits significantly higher fracture resistance under high-strain rates, little thermal fatigue data exist for this solder. Therefore, it is necessary to investigate thermal fatigue reliability of low Ag SnAgCu solder under variation of thermal stress in order to allow its implementation in electronic products with high reliability requirements. In this study, the reliability of Sn0.3Ag0.7Cu(SAC0307), a low Ag solder alloy, is discussed and compared with that of Sn3Ag0.5Cu(SAC305). Three sample types and six samples size are evaluated. Mechanical properties and microstructure of the solder joint are investigated under thermal shock cycles. It was observed that the mechanical strength of SAC0307 dropped slightly with thermal cycling relative to that of SAC305. This reveals that the failure mode of SAC0307 is different from that SAC305 under this critical condition.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.80-87
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• 2008

Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

• Journal of KSNVE
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• v.14 no.3
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• pp.38-44
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• 2004

어렵다고만 인식 되어온 비선형진동을 실험을 통하여 비선형 현상을 재현하고, 이를 이론해석을 통하여 기계계의 물리적, 역학적 동특성을 이해하는 데 초점을 두고 있으며, 실제 산업현장에서 발생하는 문제점, 즉 기계 및 설비의 고장을 진단하고 대처방안을 마련하고자 하고 있다. (중략)

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1730-1733
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• 2007

As semiconductor and MEMS devices become smaller, testing process during their production should follow such a high density trend. A circuit inspection tool "probe card" makes contact with electrode pads of the device under test (DUT). Nowadays, electrode pads are irregularly arranged and have height difference. In order to absorb variations in the heights of electrode pads and to generate contact loads, contact probes must have some levels of mechanical spring properties. Contact probes must also yield a force to break the surface native oxide layer or contamination layer on the electrodes to make electric contact. In this research, new vertical micro contact probe with bellows shape is developed to overcome shortage of prior work. Especially, novel bellows shape is used to reduce stress concentration in this design and stopper is used to change the stiffness of micro contact probe. Variable stiffness can be one solution to overcome the height difference of electrode pads.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1320-1325
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• 2008

In the manufacture of automobile suspension modules at a company as parts supplier, the design process includes the detail design and the design modification via structural and fatigue durability analyses considering PoF(physics of failure) of their weldments that are repeated more than four times sequentially. The approval of the design and the release of final drawings follows. For the suspension modules, e.g. control arms and cross member, the man-hours per worker required in the process outlined above can reach as high as 1,414hours. Application of the developed integrated design system can reduce the man-hours of 1,004. In comparison with the conventional design process, this integrated design system reduces the required time by about 40%. If expense is taken into account, a savings of approximately $192,000 is estimated, assuming the design process accounts for 1.5% of total sales for the parts supplier

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.82-91
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• 1998

This paper presents a neural networks based approach for the problem of sensor failure detection and accommodation for ship without physical redundancy in the sensors. The designed model consists of two neural networks. The first neural network is responsible for the failure detection and the second neural network is responsible for the failure identification and accommodation. On the yaw rate sensor of ship, simulation results indicates that the proposed method can be useful as failure detector and sensor estimator.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.158-161
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• 2004

In order for better management of a medical linear accelerator, the records of the operational failures of Varian CL2100C over ten years were analyzed. The failures were classified according to the involved functional subunits and each class was rated into three levels depending on operational conditions. The relationship between the failure rate and working ratio was investigated. Among the recorded failures ( total 587 failures), the most frequent failure, which was 20% of the total. was observed in the parts related to the collimation system including monitor chamber. Regrading to the operational conditions, the 2nd level of failures, that temporally interrupted treatments, was the most frequent. The 3rd level of failures, that interrupted treatment for more than several hours, was mostly caused by the accelerating subunit. The average life-time of a Klystron and Thyratron became shorter as the working ratio increased, which was 42 and 83% of the expected values, respectively. Recording equipment problems and failures in detail over a long period of time can provide a good knowledge of equipment function as well as the capability to forecast future failure. More rigorous equipment maintenance is required for old medical linear accelerator to avoid the serious failure in advance, and improve the patient treatment quality.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.203-208
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• 2016

This paper presents a fault detection and data processing algorithm for acoustic sensor systems using the multiple sensor algorithm that has originally developed for the wireless sensor nodes. The multiple sensor algorithm can increase the reliability of the sensor systems by utilizing and comparing the measurements of the multiple sensors. In the acoustic sensor system, the equivalent sound level($L_{eq}$) is used to detect the faulty sensor. The experiment was conducted to demonstrate the feasibility of the multiple acoustic sensor algorithm, and the results show that the algorithm can detect the faulty sensor and validate the data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1205-1214
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• 2004

For tile physical defects occurring in CMOS circuits which are not handled well by voltage-based testing, current testing is remarkable testing technique. Fault models based on defects must accurately describe the behaviour of the circuit containing the defect. In this paper, An efficient collapsing algorithm for fault models often used in current testing is proposed. Experimental results for ISCAS benchmark circuits show the effectiveness of the proposed method in reducing the number of faults that have to be considered by fault collapsing and its usefulness in various current based testing models.