• Nuclear Engineering and Technology
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• 제3권2호
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• pp.77-97
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• 1971

1970년 말까지 보고된 U-238, Np-237 및 Th-232의 고속중성자에 대한 핵분열단 면적 및 그 실험오차를 조사 분석하여 최소자숭직교다항식적합법에 의하여 단면적의 최적치와 95%신뢰도에 대응하는 오차범위를 계산하고 이 결과를 사용하여 분열스펙트럼에 대한 평균단면적치를 추정하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 가을 학술발표회 논문집
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• pp.95-100
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• 1990

An optimization method has been developed to find the minimum weight design of steel building structures which consist of the commercially available discrete sections. In this study, an emphasis was particularly placed on the practical applicability of optimization algorithm in engineering practice. The structure Is optimized through element optimization under the element level constraints first and then, if there is any violation of structural level constraints, it is adequately compensated by the constraint error correction vector obtained through the sensitivity analysis. A scaling procedure is introduced for the problems of large violated displacement constraint. The oscillation control in the objective function is also discussed. By dividing the available H-sections into two groups based on their section characteristics, much improved relationships between section variables were obtained and used efficiently in searching the optimum section in the section table.

• 전기학회논문지
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• 제62권3호
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• pp.431-436
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• 2013

A neutral section is installed around feeding substation(SS) and sectioning post(SP) that M phase and T phase are isolated in AC feeding system. Electric Train under "Notch-OFF" is operated by inertia within the neutral section. It causes disturbing the operation of electric trains for speed drop and driver's mistakes. A automatic changeover system with thyristor recently have taken under development. In the paper, it is introduced the configuration of train detection system and performance testing on automatic changeover system..

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.106-108
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• 2005

High accuracy and stability digital controlled power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ${\sim}$ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 A step resolution at full range and the stability of +/- 1.5 ppm for short term and +/- 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

• Structural Engineering and Mechanics
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• 제43권1호
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• pp.15-30
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• 2012

A damped Timoshenko beam element is introduced for the DOF-efficient forced vibration analysis of beam-like structures coated with viscoelastic damping layers. The rotary inertia as well as the shear deformation is considered, and the damping effect of viscoelastic layers is modeled as an imaginary loss factor in the complex shear modulus. A complex composite cross-section of structures is replaced with a homogeneous one by means of the transformed section approach in order to construct an equivalent single-layer finite element model capable of employing the standard $C^{0}$-continuity basis functions. The numerical reliability and the DOF-efficiency are explored through the comparative numerical experiments.

• Nuclear Engineering and Technology
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• 제37권1호
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• pp.101-108
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• 2005

The neutron induced nuclear cross-section data for Pd-105, Ag-109, Xe-131, and Cs-133 were calculated and evaluated from an unresolved energy to 20 MeV. The energy dependent optical model potential parameters were extracted based on recent experimental data and applied up to 20 MeV. A spherical optical model and a statistical model for the equilibrium energy, and a multistep direct and a multistep compound model for the pre-equilibrium energy were used in the calculation. The direct capture model was recently introduced for fast neutron capture. The theoretically calculated cross-sections were compared with the experimental data and the evaluated files. The total and capture cross-sections calculated using the model were in good agreement with the reference experimental data. The evaluated cross-section results were compiled in ENDF-6 format and merged with the resonance component, already adopted in the ENDF/B-VI release 8. New data library files covering from thermal to 20 MeV were created. They are at the preliminary stage of an ENDF/B- VII release.

• Nuclear Engineering and Technology
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• 제34권2호
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• pp.154-164
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• 2002

Neutron cross section data on Dy-160, Dy-161, Dy-162, Dy-163 and Dy-164 were calculated and evaluated in the energy range of 1 keV to 20 MeV using a spherical optical model, statistical model and pre-equilibrium model. The energy dependent optical model potential parameters were obtained based on the recent experimental data. The width fluctuation correction in Hauser-Feshbach particle decay and the quantum mechanical approach in pre-equilibrium analysis were introduced and gave a better cross section calculation in EMPIRE-II. The total, elastic scattering and threshold reaction cross sections were evaluated and compared with the evaluated files. The model calculated (n, tot), (n, ${\gamma}$) and (n, p) cross sections were in good agreement with the experimental data in the measured energy range. The results will be applied to ENDF/B-VI for data improvement.

• 한국강구조학회 논문집
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• 제15권4호통권65호
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• pp.389-401
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• 2003

본 연구의 목적은 H형강 단면과 콘크리트의 합성단면으로 구성된 보와 기둥의 합성 뼈대구조물에 대해 신뢰성지수를 고려한 최적 단면을 설계할 수 있는 알고리즘을 개발하는데 있다. 합성 뼈대구조물의 최적화 문제는 단면 치수를 설계변수로 취하고 목적함수와 제약조건을 형성한다. 목적함수는 구조물의 총 경비로 형성하고, 제약조건식은 단면응력과 허용응력의 신뢰성지수를 고려하여 유도한다. 합성 뼈대구조물의 단문을 최적화하는 알고리즘은 수정 Newton-Raphson 탐사법을 사용하는 SUMT기법을 사용한다. 본 연구에서 개발된 최적화 알고리즘은 1층 1경간 합성 뼈대구조물과 5층 1경간 합성 뼈대구조물의 수치예에 신뢰성지수(${\beta}=3.0$, ${\beta}=0.0$)를 고려한 합성 뼈대구조물 설계의 실용화를 위하여 적용된다. 제안된 알고리즘의 최적화 가능성과 적용성 그리고 수렴성 등을 살펴보기 위하여 수치결과들을 비교 분석한다.

• 한국강구조학회 논문집
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• 제27권2호
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• pp.231-241
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• 2015

직접강도법은 NAS(2004)와 AS/NZS 4600(2005)에 의해서 냉간성형강재의 설계에 처음 채택되었다. 이 설계법은 용접형강 부재에도 효과적으로 적용이 가능하다고 판단된다. 본 논문에서는 최근 수행된 용접형강 부재의 직접강도법 개발에 대해서 살펴보고자 한다. 용접형강 압축 및 휨부재의 설계강도식은 H, C, RHS, CHS 형강, 플레이트거더 및 보강판 단면의 실험 결과에 근거하여 개발 되었다. 직접강도법과 현행 설계기준에 의해 예측된 강도의 비교 결과를 통하여 직접강도법을 적용하여 좌굴혼합이 발생하는 용접형강 기둥 및 보 부재의 압축, 휨 및 전단강도를 합리적으로 산정할 수 있는 것을 입증하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.139-142
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• 2003

Traditionally, the thickness of fire protection materials of structural elements such as beam and column have been decided by fire test using the predominant steel section of $H-300{\times}300{\times}10{\times}15$ for column and $H-400{\times}200{\times}8{\times}13$ for beam in Korea. But this way of determination of fire protection thickness yields very unduly results. Because the temperature-increment rate of structural steel elements depends mainly on magnitude of their cross-areas. In general, the thicker size of cross-areas for structural elements, the lower temperature shows up. It had already proved that the fire protection thickness only depends on the size of cross-areas and the fire protection method for three-fide or four-side exposed conditions in European countries, the United State of America and so on. To demonstrate there would be differences among various cross-areas for structural elements, we conducted several fire tests with full-scale specimens of beams and columns. For the determination of critical temperature for steel section when the fire resistant performance is needed to be decided, we conducted with a loaded fire test for beam and column, respectively. The small column in 1.0 meter length and beam in 1.5 meter length were used in order to deprive the rational fire protection thickness of structural elements such as beam and column, respectively. After test, we could obtain there were significant temperature lass between higher cross-areas and lower cross-areas. The critical temperature of steel as a criterion is used 538$^{\circ}C$ for column and 593$^{\circ}C$ for beam which is from ASTM E 119 because we don't make provisions as critical temperature by elements. We could consider that the best way of determination of fire protection thickness is using the following multi-regression equation which was deprived from several fire tests using the concept of section factor, FR(column) = 0.17 +5191.49t A/Hp + 40.77t, FR(beam) = 0.25 +6899.31t A/Hp + 32.60t(where, FR means fire resistant time, t means thickness, A means cross-area and Hp means heated parameter).