• Proceedings of the KSR Conference
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• 2005.11a
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• pp.77-81
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• 2005

본 논문은 열차제어시스템의 고장률을 정량적으로 예측하고 입증하기 위한 방안을 제시한다. 고장률의 정량적 예측은 시스템 개발단계에서 하부시스템별 고장발생확률을 예측하여 목표 고장률과 비교하고, 고장률이 높은 하부시스템의 설계를 보완하기 위함이다. 시제품이 완성된 후에는 예측된 고장률의 입증을 위해 시운전을 통한 고장데이터를 분석하거나 신뢰성시험을 통해 고장률의 예측치를 입증한다. 본 논문에서 제시하는 열차제어시스템 고장률예측과 입증은 철도신호시스템 신뢰성, 가용성, 유지보수성, 안전성관련 규격인 IEC62278의 시스템 수명주기별 신뢰성활동을 근거로 하며, 전자부품으로 구성된 시스템고장률예측은 미국방부 전자부품 고장률예측 지침인 MIL-HDBK-217을 기준으로 사용하였다.

• Nuclear industry
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• v.23 no.7 s.245
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• pp.45-54
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• 2003

제어봉 구동 장치 제어 시스템 국산화 개발의 필요성은 경제적 관점에서 뿐만 아니라 원전의 운전과 유지 보수 측면에서도 어제 오늘 대두된 문제가 아니라 본다. 천연 자원이 부족한 우리나라에서는 급증하는 전력 수요를 충족시키기 위하여는 원전에 의존하지 않을 수 없으며, 이에 따라 가동 원전의 수명 연장을 위한 개$\cdot$보수뿐만 아니라 신규 원전 건설 계획 또한 지속적으로 수립되고 있는 것이 현실이다. 그러나 국내에 처음으로 고리 1호기가 건설된 1978년 이후 그 동안 많은 사람들의 노력에 의하여 설비 제작 관련 기술은 거의 완성 단계에 와 있다고 보여지나, 두뇌와 신경 조직에 해당하는 계측 제어 시스템 관련 기술은 아직 초보 단계를 벗어나지 못하고 있는 것이 사실이다. 이러한 우리의 현실을 극복하기 위하여 과학기술부 주관으로 원전계측제어시스템국산화사업단이 발족하였으며, 국내 원자력 산업계를 실질적으로 이끌고 있는 당사가 최종 상용화를 목표로 막대한 자금을 부담하면서 주도적으로 참여하고 있다. 지난 5월 제어봉 구동 장치 제어 시스템이 그 첫 결과물로서 발표 되었으며, 여기서는 기존 시스템과의 비교 분석을 통하여 그 개발 시스템의 기술적 경제적 특징과 의의를 살펴 보고자 한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.85-88
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• 1999

대용량 발전 시설의 개발을 목표로, 연구에 대한 많은 관심이 집중되어 온 인산형 연료전지는 이미 전 세계적으로 연구의 선두에 있는 국가들에서 수백 KW급 규모로 상용화단계에 진입해 있는 상태이고 미국 등지에서는 전력회사 등을 통하여 MW급 규모의 응용이 이루어지고 있다. 다른 연료전지에서와 마찬가지로 인산형 연료전지에서도 산소의 환원반응이 느린 점과 산소의 환원시 높은 과전압으로 인한 성능이 감소가 한계요인으로 되고 있어 이의 극복을 위한 많은 연구가 있어 왔으며 최근의 개발 방향은 발전시스템의 고성능화와 전지의 수명연장, 그리고 경제성 확보 등의 측면에서 이루어지고 있다.(중략)

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.125-126
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• 2016

본 논문에서는 자율주행차량의 ISG시스템에서 비상발전용 양방향 DC-DC 컨버터 개발을 위한 최적화 연구 결과를 발표한다. 자율주행차량의 주 전력시스템이 차단되었을 때 차량을 제어하는 시스템에 전력공급이 가능한 비상발전시스템은 현재 개발되지 않은 상태이다. 자율주행차량의 비상발전시스템의 최대 전력은 약 3kW이며 main battery 전압은 48V, sub battery 전압은 12V이다. 본 연구에서는 차량의 연비를 고려한 고전력 밀도와 배터리 수명을 고려한 전류 리플 최소화를 목표로 한다. 이를 위해 차동모드 커플더 인덕터를 가진 4상 인터리브드 방식으로 설계하였고, 최대 98.22%의 효율이 예상된다.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.335-343
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• 2010

Steel corrosion in reinforced concrete (RC) structures is a critical problem to structural safety and many researches are being actively conducted on developing methods to maintain the required performance of the RC structures during their intended service lives. In this study, concrete mixture proportioning technique through genetic algorithm (GA) for RC structures under carbonation, which is considered to be serious in underground site and big cities, is investigated. For this, mixture proportions and diffusion coefficients of $CO_2$ from the previous researches were analyzed and fitness function for $CO_2$ diffusion coefficient was derived through regression analysis. This function based on the 12 experimental results consisted of 5 variables including water-cement ratio (W/C), cement content, sand percentage, coarse aggregate content per unit volume of concrete in unit, and relative humidity. Through genetic algorithm (GA) technique, simulated mixture proportions were proposed for 3 cases of verification and they showed reasonable results with less than relative error of 10%. Finally, assuming intended service life, different exposure conditions, design parameters, intended $CO_2$ diffusion coefficients, and cement contents were determined and related mixture proportions were simulated. This proposed technique is capable of suggesting reasonable mix proportions and can be modified based on experimental data which consider various mixing components like mineral admixtures.

• Childhood Kidney Diseases
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• v.9 no.1
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• pp.76-82
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• 2005

Purpose : Regional anticoagulation with trisodium citrate for continuous renal replacement therapy(CRRT) is an effective and safe method, with lower bleeding risk. However it is not widely used because of complex current protocols used to prevent anticipated metabolic derangements. We evaluated simplified regional anticoagulation protocols with ACD-A(R) solution and commercially available calcium-containing dialysis solution. Methods : The medical records of twenty-eight patients who underwent CRRT were reviewed. Hemofilter life span according to the anticoagulation method used was compared, and laboratory findings at Pre- and 48 hours post-CRRT initiation were compared in the citrate-based CRRT group. Results : Of the twenty-eight Patients, five patients underwent citrate-based CRRT Hemofilter life span was 1.60 $\pm$ 0.72 days, showing no significant differences with the hemofilter life span in the heparin based and LMWH based CRRT group. No patients experienced hemorrhagic complications. PT, aPTT, sodium, t$CO_{2}$, iCa levels showed no difference in pre- and post-CRRT. Total calcium levels were increased. At the recommended postfilter iCa level, j.e., 0.25-0.39 mmol/L, all five patients needed increased amount of citrate infusion, and Ca infusion requirement was decreased. Conclusion : Simplified regional citrate anticoagulation with calcium-containing dialysate is an effective and safe method, and is not associated with increased hemofilter clotting. However, increased postfilter iCa level is recommended.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.73-79
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• 2009

In this paper, the structural analysis and optimization of the door supporting rail structure in the header box located at the top of the aluminum passenger safety door(PSD) at the subway station, which opens and closes regularly, is performed. In case the simple fixed boundary condition is used for the bolt fixture on the supporting rail where the glass door is moving, excessive stresses are obtained. Therefore, more realistic finite element modeling of the bolts is used at the bolt fixture in the whole structure in order to obtain the more physically acceptable FEM results. As a result, fatigue life of twenty years of the structure is obtained to satisfy the design object. Also the optimal design of cross section of the rail part is performed using the response surface method and 15% of weight of the supporting rail part on the door is reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4398-4404
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• 2015

Stainless steel sheets are widely used as the structural material for dynamic machine structures, These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding, For fatigue design of gas welded joints such as various type joint. It is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. Thus in this paper, ${\Delta}P-N_f$ curves were obtained by fatigue tests. and, ${\Delta}P-N_f$ curves were rearranged in the ${\Delta}{\sigma}-N_f$ relation with the hot spot stresses at the gas welded joints. Using these results, the accelerated life test(ALT) is conducted. From the experiment results, an life prediction model is derived and factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of welded joints and data analysis by statistic reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

• KEPCO Journal on Electric Power and Energy
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• v.3 no.2
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• pp.107-111
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• 2017

The reliability on high cycle fatigue damage mechanism for new blades manufactured by reverse-engineering is demonstrated by success-run test. Turbine blades always experience various dynamic loads in turbine operation, as well as being in resonance condition and forced by fluid-induced vibrations mostly during run-up/down, which may accumulate high cycle damage to the blades. The accidents caused by blade failure especially incur not only a lot of troubles to the machinery but also huge financial losses. Therefore it is necessary to verify the reliability of blades in advance for the safe use. The success run test for the reliability demonstration is designed and performed for the new blades using the technique known as resonant high cycle fatigue testing.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.1-7
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• 2017

While a satellite is carried into orbit by a launch vehicle, it is exposed to the severe launch environment with random vibrations and shock. Accordingly, these vibration sources affect electronic equipment, particularly the printed circuit board (PCB) in the satellite. When the launch load impacts the PCB, it causes negative behavior. This causes perpendicular bending around the boundary of fixation points that finally leads to the failure of solder joints, lead wires, and PCB cracks. To overcome these issues, the electronic equipment design must meet reliability requirements. In this paper, Steinberg's method is used to derive allowable and maximum deflection to verify design from a life perspective concerning the control board of the Antenna Pointing Driver (APD) mounted on KOMPSAT-3.