• 한국정보통신학회논문지
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• 제18권12호
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• pp.3063-3068
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• 2014

표적의 RCS(Radar Cross Section)는 레이더 탐지 성능을 결정하는데 중요한 요소이므로 표적을 효율적으로 탐지하기 위해 RCS가 크게 나타나는 위치에 레이더를 배치하는 것이 유리하다. 그러나 표적의 RCS와 함께 표적과 레이더 간의 거리 또한 레이더에 수신되는 신호의 강도를 결정하는 중요한 요소이다. 본 논문에서는 탄도미사일을 대상으로 동일한 횡축 선상에서 위치를 변경하면서 표적을 관측하였을 때 레이더에 수신되는 전력을 계산하고, 탐지 효율을 높이기 위한 레이더 배치 방안에 대해 연구하였다.

• Journal of Korean Vacuum Science & Technology
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• 제3권2호
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• pp.101-106
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• 1999

The main consideration factor to design a magnetron of the sputtering system for TFT-LCD metallization is high sheet resistance (Rs) uniformity which is provided by the high target erosion and high current efficiency. The present study has developed a rectangular magnetron for TFT-LCD to bve considered full target erosion and high film uniformity. After an aluminum-2 at.% and alloy target was installed in a magnetron source and the film was deposited on the glass of 600${\times}$720 mm, the Rs uniformity of the deposited film was measured as functions of the magnet tilt and magnet scanning configuration. And the target erosion profile was observed with the target voltage. When sputtered at 4mtorr and 10kW, the magnet tilt for the high Rs uniformity of 8.38% was 7mm. The plasma voltage at the dwell home and end for full-face target erosion, when scanned the magnetron was 120% compared to the mean voltage of the other area.

• Geomechanics and Engineering
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• 제15권3호
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• pp.879-888
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• 2018

Probability-based design codes have been developed to sufficiently confirm the safety level of structures. One of the most acceptable probability-based approaches is Load Resistance Factor Design (LRFD), which measures the safety level of the structures in terms of the reliability index. The main contribution of this paper is to calibrate the load and resistance factors of the design code for tunnels. The load and resistance factors are calculated using the available statistical models and probability-based procedures. The major steps include selection of representative structures, consideration of the limit state functions, calculation of reliability for the selected structures, selection of the target reliability index and calculation of load factors and resistance factors. The load and resistance models are reviewed. Statistical models of resistance (load carrying capacity) are summarized for strength limit state in bending, shear and compression. The reliability indices are calculated for several segments of a selected circular tunnel designed according to the tunnel manual report (Tunnel Manual). The novelty of this paper is the selection of the target reliability. In doing so, the uniform spectrum of reliability indices is proposed based on the probability paper. The final recommendation is proposed based on the closeness to the target reliability index.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.104-110
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• 2003

As exhaust emission standards are more stringent, higher conversion efficiency of automotive catalytic converter is required. In addition, catalytic converter is deteriorated during mileage accumulation of vehicle. Therefore the specification of catalytic converter should be decided in consideration of emission standards and deterioration. Because the decision of the specification of catalytic converter is required at the beginning of vehicle development procedure, it is important and necessary to fix the target values of green vehicle exhaust emissions. To do this, a linear regression analysis was done with in-use exhaust emissions data of 5 different kinds of vehicle that received US94 emission standards certification, and data handling methods including some statistical estimation were proposed. As a result, the fixed target values of NMHC, CO, NOx of green vehicle against US94 emission standards were 0.079, 0.83, 0.116, respectively. And expected in-use deterioration factor of NMHC, CO, NOx were 1.75, 2.02, 1.38, respectively. And also it was blown that even if failure rate is 30% after 80,000km driven, it might be sufficiently safe from emission failure confirmatory test of Korea. It is hopeful to make a database of in-use emissions to increase the confidence in correctness of the calculated target values.

• 대한기계학회논문집B
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• 제26권6호
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• pp.805-810
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• 2002

Development of a small gas-turbine combustor for 100㎾ class APU(Auxiliary Power Unit) has been performed. This combustor is a reverse-annular type and has a tangential swiller in the liner head to improve the fuel/air mixing and flame stability. Three main and three pilot fuel injectors of the simplex pressure-swirl type are used. The performance target at the design condition includes a turbine inlet temperature of l170k, a combustion efficiency of 99%, a pattern factor of 30%, and an engine durability of 3000 hours. Under developing the combustor, we conducted the performance test of our first prototype(TS1) with some variants. As a result of the test, the performance targets of the combustor are satisfied except that the pattern factor is about 4% higher than the target value. Therefore, the second prototype(TS2) was redesigned and the performance test was conducted with the critical focus on the pattern factor and the exit mean temperature. We adopted TS2 four variants to check the improvement of the pattern factor. As a result, the pattern factors of several variants were satisfied with the performance target. Finally, the TS2A variant was chosen as a final combustor fur our APU model.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.427-434
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• 2010

Load Resistance Factor Design method is used increasingly in geotechnical design world widely and resistance factors for drilled shafts are suggested by AASHTO. However, these resistance factors are determined for intact rock conditions, by comparison most of bedrocks in Korea are weathered condition, so that applying the AASHTO resistance factors is not reasonable. Thus, this study suggests the proper resistance factors for design of drilled shaft in Korea. The 22 cases of pile load test data from 8 sites were chosen and reliability-based approach is used to analyze the data. Reliability analysis was performed by First Order Second Moment Method (FOSM) applying 4 bearing capacity equations. As a result, when the Factor of Safety(FOS) were selected as 3.0, the target reliability index($\beta_c$) were evaluated about 2.01~2.30. Resistance factors and load factors are determined from optimization based on above results. The resistance factors ranged between 0.48 and 0.56 and load factor for dead load and live load are evaluated approximately 1.25 and 1.75 respectively. However, when the target reliability are considered as 3.0, the resistance factors are evaluated as approximately 50% of results when the target reliability index were 2.0.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.518-524
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• 2013

Recently, probabilistic assessments of nuclear power plant components have generated interest in the nuclear industries, either for the efficient inspection and maintenance of older nuclear plants or for improving the safety and cost-effective design of newly constructed nuclear plants. In the present paper, the partial safety factor (PSF) of wall-thinned nuclear piping is evaluated based on a reliability index method, from which the effect of each statistical variable (assessment parameter) on a certain target probability is evaluated. In order to calculate the PSF of a wall-thinned pipe, a limit state function based on the load and resistance factor design (LRFD) concept is first constructed. As for the reliability assessment method, both the advanced first-order second moment (AFOSM) method and second-order reliability method (SORM) are employed to determine the PSF of each probabilistic variable. The present results can be used for developing maintenance strategies considering the priorities of input variables for structural integrity assessments of wall-thinned piping, and this PSF concept can also be applied to the optimal design of the components of newly constructed plants considering the target reliability levels.

• 기술혁신연구
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• 제19권1호
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• pp.55-78
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• 2011

과학기술의 사회적 파급력이 갈수록 높아지고 있는 현대에 기술영향평가가 갖는 의미는 작지 않다. 특히 행정부에 의하여 제도화되어 수행되는 우리나라의 공식적 기술영향평가는 그 결과를 직접 과학기술 정책에 반영하도록 되어 있기 때문에 과학기술에 의한 부정적 효과나 사회적 논란에 미리 대비할 수 있게 해주는 장치가 된다. 사회적 평가를 중요시하는 기술영향평가 자체의 특징이나 매년 한 개 정도의 기술만을 대상으로 하는 제도적 기술영향평가의 운영 형태, 기술의 특징에 따라서 결정되는 평가의 내용 및 방법 등을 고려했을 때 대상기술의 선정은 다양한 관점을 고려하여 신중하게 이뤄져야 할 것이다. 그러나 지금까지 진행된 기술영향평가에서 대상기술의 선정 방식은 다양한 의견을 반영하지 못 하거나, 기술영향평가에 대한 이해보다는 정성적 토론 및 투표에 의하여 도출되는 경우가 많았다. 이 논문에서는 요인분석을 통하여 기술영향평가의 대상기술을 선정함에 있어 고려해야 할 지표들을 개발하였다. 개발된 지표는 사회적 합의의 필요성, 사회/문화적 파급효과 등 5가지로 구성되어 있으며, 각 지표들에 대한 가중치 역시 AHP 방법을 이용하여 도출하였다. 개발된 지표와 가중치를 이용하여 실제 어떻게 적용될 수 있는지를 예시를 통해 보여주었으며, 제도적 기술영향평가에 직접 적용할 때 고려해야 할 제언 또한 도출하였다. 향후 본 연구에서 도출된 지표를 활용함으로써, 제도적 기술영향평가에 적절한 대상기술을 선정할 수 있을 것이며 그를 통하여 기술영향평가 결과의 활용이 사회적 정책적으로 강화될 수 있을 것으로 전망된다.

• 대한토목학회논문집
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• 제42권3호
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• pp.299-309
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• 2022

신뢰도기반 교량설계기준에서 적용할 수 있는 새로운 종류의 차량활하중계수를 제시한다. 현재 사용하고 있는 차량활하중계수 1.8에 대한 적절성을 차량활하중의 재현주기와 교량설계수명에 기초하여 분석하였다. 중력방향하중 지배 한계상태에 대한 목표신뢰도지수 3.72는 적절한 논거 없이 너무 높게 설정된 값이며, 이에 상응하는 하중계수 1.8은 100년 설계수명 교량에서 재현주기 약 670만년 정도에 해당하는 활하중 파괴점을 나타내는 무의미한 값이라는 것을 보였다. 설계 풍속이나 지반가속도와 동일한 재현주기를 차량활하중에도 적용하면 차량활하중계수는 1.15 정도가 되고 목표신뢰도지수는 한계상태를 지배하는 하중에 따라서 2.0 혹은 2.5에 해당하게 된다. 제안한 목표신뢰도지수에 대한 전체 하중-저항계수 조합은 최적화에 의하여 산정하였다.

• 한국시뮬레이션학회논문지
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• 제24권4호
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• pp.23-28
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• 2015

탐지 분야는 전장에 영향을 미치는 요인들 중 중요한 부분이다. 기본적으로 레이더는 정해진 방향으로 탐지를 수행하기 위해 전파를 방출한다. 그러나 기존의 레이더들 대부분이 돌아온 전파를 이용해 신호처리 과정에 의해 표적을 확인할 때, 환경 감쇠 요소는 반영되지 않는다. 이러한 전자파를 이용하는 레이더는 환경적 조건에 의한 감쇠요인에 따라 탐지 결과가 달라질 수 있는 가능성을 가지고 있어, 실제 전장에서 작전상 문제가 발생할 수도 있다. 그렇기 때문에, 이 논문에서는 전파가 돌아올때, 기존의 레이더 방정식에 환경 감쇠 요인을 반영하여 더 정확한 표적을 확인하기 위한 시도를 해보고자 한다.