• 한국군사과학기술학회지
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• 제3권1호
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• pp.198-206
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• 2000

The transmission load of gear devices is important factor in the design of gear system. To design gear system precisely, an analysis and calculation methods for transmission load of gears are demanded. The purpose of this study is to develop a computer program for analyzing tooth load sharing of a spur gear system by means of the contact theory. In this paper, load transmission characteristics is identified with elastic contact problem which is assumed to quasi-static equilibrium. The modeling of spur gear tooth is accomplished by application of I-DEAS.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.110-119
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• 2013

As the technologies such as middle-range resonant WPT (wireless power transfer) advance that utilizes medium and low-frequency magnetic field, the importance of safety of such magnetic field is growing. The research on the effect of electromagnetic field on the human body has been mainly done on the GHz range of mobile phones, or 50~60Hz range of electric power systems. However, there has been relatively few works on the 100kHz~10MHz range used in the resonant wireless power transfer. Since there is a difference in the limiting value of magnetic field between widely used ICNIRP EMF guideline and IEEE C95.1 standard, there can be possible confusion when establishing EMF (Electromagnetic Field) standard on the wireless power transfer device in the future. In this paper, the induced current in the human body, which is the basic restriction of the EMF guideline, is calculated using Quasi-static FDTD method when 3D high-resolution human model is exposed to the 100kHz~10MHz magnetic field. Using this result, the feasibility of the magnetic field reference level in the ICNIRP guideline is analyzed.

• 한국항공우주학회지
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• 제43권11호
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• pp.971-977
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• 2015

복합 자이로플레인의 전진 비행 성능해석을 수행하였다. 자동회전하는 로터의 성능을 해석하기 위하여 과도모사법(Transient Simulation Method)을 이용하였으며 비행 속도 증가에 따른 동체의 공력 성능 변화를 확인하기 위해 동체에 대한 수치해석을 수행하였다. 주어진 속도와 샤프트각, 그리고 콜렉티브 피치 조건에서 준 정상 자동회전 상태를 판정하고 로터의 성능 변화를 관찰하였다. 성능해석 결과 속도가 증가함에 따라 동체의 형상에 따른 공력특성이 미치는 영향이 커지는 것으로 나타났으며 고속으로 비행하기 위해서는 유선형의 동체가 필수적이고 전진 속도 한계는 로터의 자동회전 성능에 종속적이었다.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.75-80
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• 2004

Vehicle structures are composed of many substructure connected to one another by various types of mechanical joints. In vehicle engineering it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is difficult to obtain the accurate load history of specified positions because of the errors such as modeling, measurement and etc. In the beginning of design exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic force determination is developed by the combination of the principal stresses of F. E. Analysis and experiment. Least square pseudo inverse matrix is adopted to obtain in inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these non. Finally, to verify the proposed procedure, a bus is analyzed. This measurement and prediction technology can be extended to the structural modification of any geometric shape in complex structure.

• 항공우주시스템공학회지
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• 제12권4호
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• pp.98-105
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• 2018

위성에 탑재되는 전장품의 경우 발사 진동환경에 대한 신뢰성 확보가 필수적이기 때문에 인증모델 제작 전 박스 레벨에서 설계요구조건에 대한 해석적 검증이 요구된다. 또한, 위성 전장품에는 다양한 실장 형태의 고집적 소자가 적용되기 때문에 솔더 접합부(Solder Joint)의 구조건전성 분석을 통한 신뢰성 확보가 필수적이다. 본 논문에서는 차세대 중형위성 광학 탑재체 제어기의 일부인 CCB(Camera Controller Box)에 대한 구조 설계 요구조건을 만족하기 위하여, 박스 레벨에서 모드 해석 및 준정적 해석을 수행하였다. 아울러, CCB 주요 소자의 안전성 분석을 위해 피로파괴 예측 이론에 기반한 구조 해석을 수행하였으며, 주요 소자 유한 요소 상세 모델 구축을 통한 랜덤 등가 정적 해석을 실시하여 전장품의 구조 건전성을 평가하였다.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.118-123
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• 2001

Most structures of automobile are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic farces for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic load determination is developed by the combination of the principal stresses of F.E. analysis and experiment. Inverse problem and least square pseudo inverse matrix are adopted to obtain an inverse matrix of analyzed stresses matrix. Pseudo-Practical dynamic load was calculated for Lab. Test of sub-structure. GUI program(PLODAS) was developed for whole of above procedure. This proposed method could be extended to any geometric shape of structure.

• Computers and Concrete
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• 제30권4호
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• pp.277-287
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• 2022

Due to the scarcity of extortionate experimental data, fatigue failure of the reinforced concrete (RC) element might be achieved economically adopting nonlinear finite element (FE) analysis as an alternative approach. However, conventional implicit dynamic analysis is expensive, quasi-static method overlooks interaction effects and inertia, direct cyclic analysis computes stabilized responses. Apart from this, explicit dynamic analysis may provide a numerical operating system for factual long-term responses. The study explores the fatigue behavior based on a simplified explicit dynamic solution employing nonlinear time domain analysis. Among fourteen RC beams, one beam is selected to validate under static loading, one under fatigue with the experimental study and other twelve to check the detail fatigue behavior. The SWOT (Strength, Weakness, Opportunities, Threats) analysis has been carried out to pinpoint the detail scenario in the adoption of numerical approach as an alternative to the experimental study. Excellent agreement of FE and experimental results is seen. The 3D nonlinear RC beam model at service fatigue limits is truthful to be used as an expedient contrivance to envisage the precise fatigue behavior. The simplified analysis approach for RC beam under fatigue offers savings in computation to predict responses providing acceptable accuracy rather than the complicated laboratory investigation. At higher frequency, the flexural failure occurs a bit earlier gradually compared to the repeated loading case of lower frequency. The deflection increases by 6%-10% at the end of first cycle for beams with increasing frequency of cyclic loading. However, at the end of fatigue loading, greater deflection occur earlier for higher load range because of more rapid stiffness degradation. For higher frequency, a slight boost in concrete compressive strains at an initial stage of loading has been seen indicating somewhat stepper increment. Stiffness degradation in larger loading cycle at same duration escalates the upsurge of the rate of strain in case of higher frequency.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.232-238
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• 2009

The objective of this study is to investigate the suitable design for a domestic CWP pump, which is used in cooling-water intakes for the unit 3 and 4 of Yeonggwang nuclear power plant. All the simulations are performed, using CFD method with a commercial code STAR-CCM+ version 3.02. After modeling a present design of the pump, the flow around the rotating blade was calculated by using quasi-static method and sliding mesh method with the almost same condition as an actual state. Based on fundamental simulations with various depth of sea water, the reference pressure for the boundary condition of the present study was decided. To verify the reliability of the calculation results, the suction flow rate of the data was compared with that of the experimental data. As a result of this comparison, it is confirmed that two results are fairly consistent. For the improvement of the suction flow rate, computational analysis was done by changing a flow channel and blade shapes. It is shown that the suction flow rate of the new pump was improved.

• 한국전산유체공학회지
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• 제14권3호
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• pp.69-75
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• 2009

The objective of this study is to investigate the suitable design for a domestic Circulating water pump(CWP), which is used in cooling-water intakes for the unit 3 and 4 of Yeonggwang nuclear power plant. All the simulations are performed, using CFD method with a commercial code STAR-CCM+ version 3.02. After modeling a present design of the pump, the flow around the rotating blade was calculated by using quasi-static method and sliding mesh method with the almost same condition as an actual state. Based on fundamental simulations with various depth of sea water, the reference pressure for the boundary condition of the present study was decided. To verify the reliability of the calculation results, the suction flow rate of the data was compared with that of the experimental data. As a result of this comparison, it is confirmed that two results are fairly consistent. For the improvement of the suction flow rate, computational analysis was done by changing a flow channel and blade shapes. It is shown that the suction flow rate of the new pump was improved.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.168-173
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• 2002

The durability test, along with the crashworthiness test, requires the most time and expense in the vehicle development process. The durability design using CAE tools reduces the time required for both the durability test and actual vehicle production. Existing dynamic stress analyses designed fir the analysis of vehicle fatigue mainly calculate the dynamic stress history and fatigue after performing dynamic analysis and stress analysis with relevant software applications and then superpositioning the dynamic load history and stress influence coefficient at each joint. This approach is a complex process, taking into account the flexibility of the parts. It is, however, incapable of giving accurate consideration to the contacts between components, the non-linearity of materials, and tire-road surface interactions. This approach also requires that the analysts have an expertise in software applications of various kinds or an expert in each area must perform the analysis. This requires as a great deal of manpower and time. In order to complement the existing approaches for dynamic stress analysis, this study aims at the following: (1) to suggest the simple and accurate analysis technique which is capable of producing all the possible necessary results; (2) to reduce dramatically the time and manpower needed to construct a model designed to analyze dynamics, quasi-static stress, and fatigue; and (3) to enable an accurate analysis of fatigue by improving the accuracy of dynamic stress. we verify the presented analysis method through durability evaluation of the knuckle of passenger car.