• 산업공학
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• 제25권4호
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• pp.405-415
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• 2012

The reliability performance measures for low and high or continuous demand modes of operation of safety instrumented systems(SISs) are examined and compared by analyzing the official definitions in IEC 61508 standard. This paper also presents a status of common cause factor(CCF) models used in IEC 61508 and problems relating CCF modelling are discussed and ideas to solve these ones are suggested. An example with mixed M-out-of-N architecture is carried out to illustrate the proposed methods.

• 한국콘텐츠학회논문지
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• 제12권1호
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• pp.30-37
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• 2012

선형 비틀림 구조를 갖는 메모리 시스템은 SIMD 구조에 적합한 메모리 시스템으로써, 2차원 데이터 배열인 $M{\times}N$에서 임의의 위치로부터 임의의 간격을 갖고 다양한 접근형태들로, m개의 메모리 모듈들에서 n개의 데이터를 동시에 접근할 수 있다. 그러나 이러한 메모리 시스템은 논리적인 2차원 $M{\times}N$ 데이터 배열을 지원하기 위해 $m{\times}cells$의 물리적인 메모리 용량이 필요하지만, 적어도 (m-n)${\times}cells$만큼의 메모리 셀은 사용되지 않는다. 여기서 cells는 (M-1)/q+(N-1)/$p{\times}{\lceil}M/q{\rceil}+1$이다. 본 논문에서는 이러한 메모리 시스템의 모든 기능들을 수용하면서 t>0인 조건 하에 사용되지 않는 메모리 셀들 중 $(n{\times}t){\times}N/p$ 만큼을 n개의 처리기들에 지역 버퍼 메모리로 제공할 수 있는 방법을 제안한다.

• 한국조경학회지
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• 제29권4호
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• pp.91-99
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• 2001

This study was carried out to investigate the effects of mowing height, rolling, N-fertilizing, and season on green speed(i.e., ball-roll distance) for developing and implementing a program of increasing green speed in Korean golf courses. Data were subjected to multi-regression analysis using SPSSWIN(Statistical Package for the Social Science), which collected from Yong-Pyong golf course greens selected to investigate. The results was as follows. 1) The multi-regression analysis of mowing height, rolling times, and N-fertilizer application rates on spring green speed was as follows; $Y_1$(spring green speed)=4.287+0.155X$_1$(rolling times)-0.131X$_2$(the amount of N-fertilizing)-0.251X$_3$(mowing height). 2) The multi-regression analysis of mowing height, rolling times, and N-fertilizer application rates on summer green speed was as follows; $Y_2$(summer green speed)=4.833-0.423X$_3$(mowing height)+0.146X$_1$(rolling times)-0.107X$_2$(the amount of N-fertilizing). 3) The multi-regression analysis of mowing height, rolling times, and N-fertilizer application rates on fall green speed was as follows; $Y_3$(fall green speed)=4.651-0.383X$_3$(mowing height)+0.142X$_1$(rolling times)-0.103X$_2$(the amount of N-fertilizing). 4) As mowing height was lowered by 1mm, green speed increased by 0.251~0.423m. As rolling times increased by 1(one), green speed increased by0.142~0.15m. As the amount of N-fertilizing increased by 1g/$m^2$, green speed decreased by 0.103~0.131m. The season also affected green speed. In comparison with spring green speed, summer green speed decreased by 0.145m and fall green speed decreased by 0.144m.

• 한국정보통신학회논문지
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• 제11권8호
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• pp.1558-1563
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• 2007

논문은 fractional-N 방식의 주파수 합성기(PLL)를 낮은 차수의 ${\Delta}{\Sigma}$변조기로 더욱 높은 성능의 PLL로 설계하기 위하여 대역폭 가변 방식의 PLL과 ${\Delta}{\Sigma}$방식의 fractional-N PLL의 구조를 합성한 새로운 방식의 PLL을 제안한다. Matla으로 대역폭 가변을 이용한 ${\Delta}{\Sigma}$방식의 fractional-N PLL의 시뮬레이션을 수행하여 제안된 구조의 특성을 관찰하였다. 본 논문의 대역폭 가변 PLL은 HSPICE 0.35um CMOS 공정을 이용하여 시뮬레이션 하였고, 그 결과 제안된 PLL은 빠른 록이 가능하고 fractional spur를 20dB 정도 낮출 수 있었다.

• 한국농촌건축학회논문집
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• 제14권3호
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• pp.101-108
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• 2012

The purpose of this study was to set and analyze the feasibility and survey of the Hanok(The traditional Korean style house) housing complex project within Seoul metropolitan area. The results of this study were as follows. First of all, a survey was carried out to find out the optimum Hanok style. The survey showed that many people chose a frond and back yard garden as a merit of Hanok and pointed out the weak crime prevention as a weakness of Hanok. The optimum size for a Hanok was from $264m^2$ to $330m^2$ and living space was from $100m^2$ to $132m^2$. And people considered about 120% of what the apartment sells for as the reasonable price of a Hanok. Based on the survey, this study planned a Hanok housing complex on a lot that has competitive price and analysed the feasibility of the housing plan. The result was that Hanok's construction cost per $3.3m^2$ to be a marketable product has to be below about 6 million Won. As a result, the construction cost-saving through the advanced technology and planning to meet the changing customers' needs are needed to vitalize Hanok's supply.

• 대한조선학회논문집
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• 제48권6호
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• pp.539-543
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• 2011

Recently, to reduce the noise and vibration levels of ships, high skewed marine propellers with thinner thickness are adopted widely, however, such propeller design trend causes to reduce the strength of blades. Propeller blades are rotating continuously in irregular wake field of ships. So, it is necessary to examine the strength of them precisely including from a viewpoint of fatigue strength. In present paper, the fatigue strength of propeller blades was investigated. Firstly, fatigue tests for Al Bronze, the representative propeller material, were carried out. The S-N curve was obtained for the assessment of the fatigue crack initiation life. And the material properties C, m for the fatigue crack propagation analysis based on the Paris' equation were derived. For the 2nd stage, the structural responses of propeller blades in irregular ship wake field was carried out using the finite element analysis code. And the fatigue strength of propeller blades were considered based on the calculated stress levels and material characteristics for fatigue strength.

• 한국농촌건축학회논문집
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• 제20권1호
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• pp.19-26
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• 2018

The roof improvement project is being carried out under the government's leadership for the sake of national welfare. The project is to replace the asbestos slate roof with a metallic one. In this study, the structural safety of the improved roof was examined and the project guidelines were reviewed. The causes of the roof damage were investigated and the structural analysis was performed for the roof frame subject to wind and snow loads. Metallic roof assemblies have higher strength and load resistance capability than usual slate ones, so the structural safety is governed by the frame. The stresses of the roof frame elements caused by the wind and snow loads were analyzed according to roof frame with various spacings between the rafters and the purlins. Wind load analysis was performed by 24, 28, and 38 m/sec of the basic wind speed. Snow load analysis was carried out by 0.5, 1.0 and $2.0kN/m^2$ of the ground snow load. As the analysis result, the current spacing and the size of the lumber did not satisfy the Korean building code specification. To secure the safety of the roof improvement project, the spacing of the roof frame elements and the size of the lumber should be determined based on the analysis results by structural engineers.

• International Journal of Korean Welding Society
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• 제2권1호
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• pp.33-39
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• 2002

The effect of out-of-plane loads on the fatigue strength of welded steel structures is examined through fatigue tests with weldment of two fillet weld joint types. The results of the fatigue tests are compared with those under axial loads, on the basis of the hot spot stress range at the weld toe. From the result of the comparison, a method on how to incorporate the effect of the out-of-plane bending stress is proposed using design S-N curves derived from fatigue tests under the axial load. The proposed method is useful for rational assessment of the fatigue strength of fillet-welded structures, where combined stresses of the in-plane axial stress and the out-of-plane bending stress are induced simultaneously due to the complexity of applied loads and structural geometry.

• 한국조경학회지
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• 제32권6호
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• pp.95-102
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• 2005

This study was carried out to find out the heavy metal contents and the physico-chemical properties for the improvement of dredged soils which widely exist in lowlands of Korea. At first all the average heavy metal contents were close to background level and were much lower than concern level of the Soil Environment Conservation Act of Korea. And the results of physical analyses of soils showed on the average $2.46\~2.74 Mg/m^3$ in Particle density, $0.45\~2.45 kg/kg$ in soil water contents, $0.34\~0.90 Mg/m^3$ in bulk density, $0.67\~0.87m^3/m^3$ in porosity, $2.18\times10^{-5}\~1.20\times10^{-8} m/s$ in saturated hydraulic conductivity, R0.12\~0.65 m^3/m^3$ in available water contents. Finally the results of chemical analyses of soils showed on the average $6.5\~8.2\;in\; pH,\;5\~48 g/kg\;in\; OM,\;0.48\~4.51g/kg\;in\;T-N,\;19\~25mg/kg$ in available phosphate, $0.28\~11.80 dS/m\;in\;EC,\;8.7\~38.1cmol/kg$ in CEC, respectively Accordingly, the physicochemical properties of soils ought to be analyzed accurately before dredging for effective using of dredged soils. And it will be more effective, if the dredged soils are used with proper balance among each content of components with consideration to the physicochemical properties of common soils.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.301-309
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• 2022

This work aims to establish some X-ray qualities recommended by the International Standard Organization (ISO) using the half-value layer (HVL) and H_p(10) dosimetry approaches. The HVL values of the following qualities N-60, N-80, N-100, N-150 and N-250 were determined using various attenuation layers. The obtained results were compared to those of reference X-ray beam qualities and a good agreement was found (difference less than 5% for all qualities). The GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations) radiation transport Monte Carlo toolkit was employed to simulate the production of X-ray spectra. The characteristics HVLs, mean energy and the spectral resolution of simulated spectra have been calculated and turned out to be conform to the ISO reference ones (difference less than the limit allowed by ISO). Furthermore, the conversion coefficients from air kerma to personal dose equivalent for simulated and measured spectra were fairly similar (the maximum difference less than 4.2%).