• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.568-572
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• 2001

An industrial vibratory conveyor system is devised for large-scale feeding by the low-power, using natural frequency of the system. The important thing in this system is to determine the natural frequency and to drive by it. The purpose of this study is to build up reliance on the system with changing of element parameters for vibration characteristics of balancing type vibratory conveyor by using F.E.M. modeling. For investigating the natural frequency, modal testing is performed by using impact hammer, accelerometer and LMS/Vibration Analysis System. Experimental results are compared with F.E.M results. The results of the comparisons within the errors of less than 2 percent can verify the reliability of the F.E.M. analysis of the system. Also we can verify that the characteristics of natural frequency have linearly decreased(-6%) as adding the mass($50{\sim}600kg$). We can find that controlling driving frequency is necessary for triggering the natural frequency, but natural frequency is less affected by adding the mass on the balancing weight.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 박판성형기술의 진보
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• pp.163-172
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• 1994

The Aerospace and automobile industries have need to avoid sheet-metal forming problem such as incorrect springback after forming and trimming process, excessive thinning/tearing, wrinking/perkering. It is common practice to use costly trial-and-error experimental methods to develop tooling and manufacturing process parameters. Experimentation should be complemented with computer simulation to reduce cost and leadtime in manufacturing and to influence the design of components. In this study, firstly we solved the springback problem after drawing and trimming process of KFP(F100-229) engine airsealing bearing support part(53H00) forming and studied on the effect of several process parameters on the gap between the formed blank and punch shape using the implicit F.E.M code(ABAQUS). Secondly by the three dimensional dynamic analysis using the explicit. F. E. M code (LS-DYNA3D), we studied on the effect of several process parameters which can be used for avoid tearing and wrinking during the drawing process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.591-593
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• 2005

This paper presents the dynamic analysis of a humanoid robot using Nastran that is one of FEM analysis program. Generally, computer program based on the Lagrange-Euler method or Newton-Euler method was used for dynamic analysis of a robot. The Lagrange-Euler method requires much calculation performance and it is also hard to apply to complex structure, and the Newton-Euler method limits accurate modeling and calculation for closed structure like a humanoid robot. In this paper, mechanical and structural data are obtained from the Nastran. It is possible for Nastran to make model similar to real system and can apply a physical properties and laws to model. So, accurate simulation is possible. From this result, accurate data is gained by Nastran. Furthermore, this method is shown to be a useful method that guarantees accuracy for trajectory planning.

• 대한조선학회지
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• 제25권1호
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• pp.33-46
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• 1988

This paper describes a simplified method for estimation of the ultimate compressive strength of actual ship panels with initial deflection of complex shape. The proposed method consists of the elastic analysis using the large deflection theory and the rigid-plastic analysis based on the collapse mechanism which also includes the large deformation effect. In order to reduce the computing time for the elastic large deflection theory and the rigid-plastic analysis based on the collapse mechanism which also includes the large deformation effect. In order to reduce the computing time for the elastic large deflection analysis, only one term of Fourier series for the plate deflection is considered. The results of the proposed method are in good agreement with those calculated by the elasto-plastic large deflection analysis using F.E.M. and the computing time of the proposed method is extremely short compared with that of F.E.M.

• Applied Biological Chemistry
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• 제32권2호
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• pp.170-177
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• 1989

2개의 m-methyl group이 치환된 m-xylyl N-methylcarbamates(MXNMC)가 비치환된 phenyl N-methylcarbamates(PNMC)보다 높은 살충작용을 나타내는 이유를 알아보기 위하여 이들 두 유도체들이 확장 $H\ddot{u}ckel$(EHT) 이론에 따른 분자궤도(MO) 이론과 회귀 및 자유에너지 관계(LFER) 분석에 의하여 연구되었다. 가장 안정한 입체구조는 phenyl group이 N-methylcarbamyl group의 면에 대하여 수직(${\theta}=90^{\circ}$)인 형태(Z,Z)이었으며, 회귀분석은 $pI_{50}$ 상수들과 meta-위치 및 m-methyl group의 수소원자 하전과 LUMO에너지의 계산된 MO량을 변수로 취했을 경우가 가장 좋은 상관관계를 나타내었다. Carbamylation 반응에 관한 LFER분석 결과, PNMC에서는 공명(R)-효과(40%)보다 장 (F) 효과(60%)가 약간 컸으나(F>R), MXNMC의 경우에는 R-효과(98.6%)가 F-효과(1.4%)보다 월등히 큰 값($R{\gg}F$)을 보였다. 이와 같은 사실로부터 MXNMC의 살충작용이 증진되는 것은 m-dimethyl group에 의한 hyperconjugation의 결과라고 믿어진다.

• 전기화학회지
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• 제3권2호
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• pp.109-114
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• 2000

다결정 $Ir/H_2SO_4$수성 전해질 계면에서 중간주파수 구간의 위상이동 변화와 Langmuir흡착등온식 사이의 관계를 교류임피던스 방법 즉 위상이동 방법을 이용하여 연구 조사하였다. 간소화된 계면 등가회로는 전해질저항(Rs), Faraday저항$(R_F)$, 흡착유사용량$(C_\phi)$ 등가회로 요소$(C_P)$의 직렬접속으로 구성된다. 음전위(E)에 대한 위상이동$(-\phi)$과 표면피복율$(\theta)$ 변화율$[\Delta(-\phi)/{\Delta}E,\;{\Delta}{\theta}/{\Delta}E]$을 비교 및 제시하였다. 지연되는 위상이동$(-\phi)$은 음전위(E) 및 주파수(f)에 따르며, $\phi=tan^{-1}[1/2{\pi}f(R_s+R_F)C_P]$이다. 중간주파수(1 Hz)에서 위상이동 변화$(-\phi\;vs.\;E)$는 Langmuir흡착등온식 $(\theta\;vs.\;E)$의 결정에 적용할 수 있는 실험적인 방법이다. 다결정 Ir/0.1 M $H_2SO_4$ 전해질 계면에서 수소의 흡착평형상수(K)와 흡착표준자유에너지 $({\Delta}G_{ads})$는 각각 $2.0\times10^{-4}$와 21.1kJ/mol이며 과전위 수소흡착(OPD H)에 기인한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.42-47
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• 1997

In this study, the drawing characteristics of circular drawbead are examined with the plane strain elastic-plastic FE Method by varying the process variables such as friction coefficient, drawbead radius, and closing depth. Numerical analysis are carried out by 2-D elastic-plastic F.E.M. The results are compared with the existing experimental results about the drawing force, the die clamping force, and the strain distribution of upper and lower sheet faces

• 전기의세계
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• 제16권1호
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• pp.14-18
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• 1967

To analyze th frequency modulation system the characteristic equation of the F-M system, i.e., Mathieu's equation, is derived from the equivalent circuits of direct modulation system. The analysis of F-M equation is undertaken by the Yonsei 101 Analog Computer. And the computer solution is compared with the theoretical solution. It is concluded that not only the frequency but also the amplitude of the carrier wave are changed by varying the modulation index and the system becomes unstable if the modulation index is increased near to unity.

• 한국산림과학회지
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• 제73권1호
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• pp.9-13
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• 1986

Juniperus rigida의 경남(慶南)과 충북(忠北)의 두 산지종(産地種)에 대하여 핵형분석(核型分析)을 하였다. 염색체수(梁色體數)는 두 산지종(産地種) 공(共)히 2n=22이다. 두 산지종(産地種)에 있어 가장 공통적(共通的)인 특징(特徵)을 나타낸 염색체(染色體)는 두완(短腕)에 secondary constriction을 지닌 No.7 이고, 가장 특이적(特異的) 특징(特徵)을 한 염색체(染色體)는 secondary constriction을 지닌 경남산(慶南産)의 No.9와 충북산(忠北産)의 No.5 염색체(染色體)이다. 핵형식(核型式)은 다음과 같다. 경남산지종(慶南山地種) $$K(2n)=22=2A^m+2B^m+2C^m+2D^{sm}+2E^{st}+2F^m+2^{sc}G^m+2H^m+2^{sc}I^t+2J^{st}+2K^m$$ 충북산지종(忠北山地種) $$K(2n)=22=2A^m+2B^m+2C^m+2D^{st}+2^{sc}E^{sm}+2F^m+2^{sc}G^m+2H^m+2I^m+2J^{st}+2K^{sm}$$.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권11호
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• pp.539-545
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• 2001

A simple analysis method for inverter-fed induction motor using F.E.M and harmonic equivalent circuit is proposed. And an optimum shape of rotor slot for 2Hp inverter-fed induction motor is determined by combining the proposed analysis method and an optimization algorithm. Conjugate gradient method is used for the optimization algorithm. The optimization is performed for higher efficiency and reduction of harmonic loss in the inverter-fed induction motor. The optimization results are verified by comparing with those of the time-step F.E.A.