• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.57-64
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• 2001

For the dynamic nonlinear analysis of stiffened plate and shell structures, total Lagrangian formulation is presented based upon the degenerated shell element considering finite rotation effects. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. In the elasto-plastic analysis, the return mapping algorithm based on the consistent elasto-plastic tangent modulus is applied to collapse analysis of shell structures. Newmark integration method is used for dynamic nonlinear analysis of shell structures under dynamic forces.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.53-60
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• 2001

This paper considers a modeling for the MIMO magnetic bearing system. The rotor is flexible and has a complex shape. To obtain the nominal plant transfer functions, we perform a numerical analysis by using the finite element method(F.E.M.) for the rotor's dynamics, and make a nominal model by reducing the modes from the results. And, we have experimented on the frequency response by a closed-loop identification method, and compared it with the simulation's result on the closed-loop control system.

• Congress of the korean instutite of fire investigation
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• 2010.12a
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• pp.239-248
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• 2010

2008년도 사고설비별 전기화재 발생현황을 살펴보면 전기화재중 전기배선 및 배선기구에서 발화한 화재가 2,540건으로 전기화재 발생 중 25.95 %를 점유하였다. 또한 사고전압별 전기화재 발생현황으로 220/380 V에서 화재가 6,320건(64.4 %)으로 전기화재의 대부분을 점유하였다. 전기화재는 단락, 과전류, 접촉불량, 트래킹 등 9가지로 분류할 수 있다. 이러한 전기로부터 재해를 막기 위하여 누전차단기나 배선용차단기를 사용하여 일부의 전기화재 원인을 차단할 수 있으나 차단기 자체에서 발생하는 원인에 대하여는 보호할 전기기기가 부재하다. 본 논문에서는 최근 실화법의 적용으로 일반적으로 전기화재로 취급되어지지만 보다 세밀히 조사하면 제조결함, 사용자 부주의, 설치 및 환경에 따른 위험성을 분석하고 전기설비에서의 화재 발생에 대한 예방대책에 활용할 수 있도록 연구하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.136-136
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• 2010

일반적인 플라즈마의 밀도측정에는 랑뮤어(Langmuir)탐침법이 보편적으로 사용되고 있다. 그러나 LCD(Liquid Crystal Display)나 PDP(Plasma Display Panel) 등 미세 방전 플라즈마는 이러한 방법으로는 측정이 너무 어려워서 잘 사용되지 않고 있다. 그래서 이러한 경우 간접측정 방법이 사용되고 있다. 본 연구에서는 알려진 간접 측정방법과는 다른 방식인 spectrum analyzer를 사용하여 측정해 보았다. LCD에서 사용되는 BLU(Back Light Unit)lamp와 PDP panel을 각각 측정하여 기존의 간접측정 방법의 결과와 비교해 보았다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.255.1-255.1
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• 2014

태양전지 도핑공정은 대부분 퍼니스(furnace)도핑으로 제작된다. 퍼니스 도핑 공정은 고가의 장비와 유지 비용이 요구되며 국부적인 부분의 도핑은 제한적이다. 또한 도핑 시 온도와 공정 시간이 태양전지의 전기적 특성을 결정짓는 중요한 변수 이다. 그리하여 최근 많은 연구가 진행되는 대기압 플라즈마를 이용하여 도핑공정에 응용하고자 한다. 본 연구에서 대기압 방전 시 전원은 DC-AC 인버터를 사용하였다. 인버터의 최대 출력 전압은 최대 5kv, 주파수는 수십 KHz 이다. Ar 가스는 MFC(Mass Flow Controller)를 사용하여 조절하였다. 대기압 플라즈마를 이용한 태양전지 도핑 시 소스와 ground 거리에 따른 대기압 플라즈마의 방전을 열화상카메라(thermo-graphic camera, IR)로 온도의 변화 측정 및 광학적 발광분광법(Optical Emission Spectroscopy, OES)을 통해 불순물(질소, 산소)을 측정 하였다. 웨이퍼 도핑 후 생성된 웨이퍼를 측정 및 분석을 하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.257-262
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• 2001

Single crystalline films of La doped YIG(yttrium iron garnet) were grown by the liquid phase epitaxy. The lattice constants of films obtained by DCD(double crystalline diffractometer) measurement increased with increasing La contents in films. In particular, lattice constants of films grown wiht Y/La=20 solution were nearly same as those of GGG (gadolinium gallium garnet) substrate. The saturation magnetization measured with VSM (vibrating sample magnetometer) was about 1750Gauss which is the same as that of pure YIG irrespective of La contents in films. FMR(ferromagnetic resonance) linewidth of La doped YIG was smaller than that of pure YIG. Since appropriate La doping decreases the lattice mismatch between film and substrate, the FMR linewidth was Y/La=20 in this experiment.

• Journal of Applied Reliability
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• v.15 no.3
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• pp.163-169
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• 2015

In this paper, the evaluating test methods of the fire and the electric shock on the led lamp supply using the house is proposed. We analyzed FMEA in order to analyze the mechanism of the fire and the electric shock of the led lamp supply and designed durability tests on the environment ($85^{\circ}C$, 85% R.H.) and obtained through the two-step QFD and tested. We verified the evaluating test methods of the fire and the electric shock on the led lamp supply using the house through the analysis of the test results.

• Journal of Power System Engineering
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• v.1 no.1
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• pp.91-97
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• 1997

Recently, it is increased by degrees to construct complex and large structures. In general, in order to solve the dynamic problem of these structures they have used finite element method(FEM). In this method, however, it is necessary to prove whether its results are correct or not. Therefore it requires much effort, time and many expenses for dynamic analysis of complex and large structures. Authors have developed the transfer dynamic stiffness coefficient method(TDSCM) which is the new vibration analysis method for complex and large structures on personal computer, and confirmed that the results of this method are good for these structures on personal computer. In this paper, TDSCM is applied to the torsional vibration analysis for the shaft system which consist of concentrated disks and shafts of continuous body. First, we formulate algorithms for torsional free and forced vibration analysis, and compare the results of TDSCM and FEM.

• Journal of Power System Engineering
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• v.3 no.1
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• pp.74-79
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• 1999

This paper describes formulation for algorithm of time historical response analysis of vibration for straight-line structure. This method is derived from a combination of the transfer stiffness coefficient method and the Newmark method. And this present method improves the computational accuracy of the transient vibration response analysis remarkably owing to several advantages of the transfer stiffness coefficient method. We regarded the structure as a lumped mass system here. The analysis algorithm for the time historical response was formulated for the straight-line structure containing crooked, tree type system. The validity of the present method compared with the transfer matrix method and the Finite Element Method for transient vibration analysis is demonstrated through the numerical computations.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.92-97
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• 2007

It is important to compute the structural analysis of plate structures in structural design. In this paper, the author uses the finite element-transfer stiffness coefficient method (FE-TSCM) for the structural analysis of plate structures. The FE-TSCM is based on the concept of the successive transmission of the transfer stiffness coefficient method and the modeling technique of the finite element method (FEM). The algorithm for in-plane structural analysis of a rectangular plate structure is formulated by using the FE-TSCM. In order to confirm the validity of the FE-TSCM for structural analysis of plate structures, two numerical examples for the in-plane structural analysis of a plate with triangular elements and the bending structural analysis of a plate with rectangular elements are computed. The results of the FE-TSCM are compared with those of the FEM on a personal computer.