• 대한기계학회논문집A
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• 제35권10호
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• pp.1187-1191
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• 2011

이 응용논문에는 적응형 로드리미터에 대해 기술되어 있다. 적응형 로드리미터는 안전벨트의 구성품 중 하나이며, 이는 승객의 다양한 체중과 키에 따라 하중량을 고하중과 저하중으로 변환시킬 수 있는 장치이다. 최근, FMVSS 208규정은 다양한 더미크기에 대해 엄격한 안전기준을 요구하고 있다. 이에 따라 우리는 고하중 조건과 저하중 조건 시 각각 더미에 흉부 상해정도를 알아보았고, 실험을 통해서 벤치마킹모델의 하중조건을 확인하였다. 이를 토대로 적응형 듀얼레벨 로드리미터를 개발하여 성능 실험을 실시하였고, 유한요소해석을 통해 설계 개선점을 확인하였다.

• 한국강구조학회 논문집
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• 제26권4호
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• pp.323-334
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• 2014

본 연구에서는 표준화재에 노출된 무피복 콘크리트충전강관(CFT)기둥의 내화성능 및 거동 특성을 파악하고자 화재실험 및 수치해석 연구를 수행하였다. 실험변수로는 기둥높이, 하중비, 단면크기를 고려하였고, 이들이 CFT 기둥의 내화성능에 미치는 영향을 알아보고자 단면내 온도변화 및 축변형을 분석하였다. 실험결과 모든 실험체의 강관에서 국부좌굴이 발생, 콘크리트로 하중전이가 일어났고, 이후 콘크리트 압괴로 이어졌다. 이는 CFT 기둥의 전체 휨좌굴과 함께 국부좌굴이 내화설계의 주요 변수로 고려되어야 함을 시사한다. 하중비가 증가할수록 콘크리트저항구간이 줄어들면서 전체적인 내화시간이 감소하였다. 강재한계온도에 근거한 합성부재의 내화성능평가는 실제 하중지지력에 의한 내화시간에 비해 다소 보수적임을 확인하였고, 기존 연구자들의 제안식에 의한 성능예측결과도 실제 내화성능과 비교해볼때 개선의 여지가 있었다. 화재시 CFT 기둥의 내화성능을 예측하기 위하여 유한요소해석을 수행하였고, 실험결과와 비교할 때 신뢰성 있는 예측값을 나타냄을 확인하였다.

• Structural Engineering and Mechanics
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• 제68권3호
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• pp.277-287
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• 2018

This paper presents the experimental study of nine pieces of reinforced concrete (RC) short columns. RC short columns were tested with cyclic loading with displacement control under the influence of constant axial load with load index of 0.2. Three columns within the tested nine columns are reference columns which have the details of the reinforcement given in the modern regulations and six of them are 150 mm and 100 mm externally collared columns. In addition to the parameter of the collar spacing, aspect ratio (as=2-1.5-1) is also considered as a parameter. The data obtained from experimental results have shown that externally collar contributes significantly to increasing the shear resistance of RC short columns and limiting the shear dominant behavior. It has been observed that the effectiveness of the externally collar increases with the decrease of the aspect ratio.

• Structural Engineering and Mechanics
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• 제4권4호
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• pp.383-396
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• 1996

In this paper, the behavior of plates partially restrained against rotation under stress gradient is investigated. As a first stage, an energy formulation is presented to model this boundary condition and a general expression is derived for the prediction of the elastic buckling of the plate under this general loading condition. The accuracy of the derived expression is compared numerically using the Galerkin method with other available data for the two limiting conditions of rotationally free and clamped boundaries. Results show that the prediction is within a 5% difference. The influence of rotational restraint and stress gradient upon the buckling load and the associated buckling mode is investigated. Numerical results show sensitivity of the buckling mode to the degree of rotational restraint and the variation of the buckling load with the stress gradient.

• 한국공간구조학회논문집
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• 제1권2호
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• pp.111-116
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• 2001

This paper is a study on the elasto-plastic analysis of reinforced concrete precast large panel connections by rigid element spring model. In the analysis of rigid element spring model, each collapsed part or piece of structures at limiting state of loading is assumed to behave like rigid bodies. The present author propose new elements for the improement and expansion of the rigid element spring model. In this study, it is proposed how the rigid element method can be applied to the elesto-plastic analysis of precat large panel connections. Some numerical results of analytical modeling and load displacement curves are shown.

• 태양에너지
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• 제9권2호
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• pp.58-68
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• 1989

This paper describes an experimental study that was performed to determine the limiting factors on the power output in the closed cycle Electro-Hydro-Dynamic generator of small capacity. A corona discharge for producing unipolar charged particles used as the charging method. The experiment demonstrated that the corona method of charging was an efficient and effective means of producing unipolar charged particles. Four factors having an effect on the power output characteristics of EHD generator are discussed and examined experimentally, using methyl alcohol and kerosene as working fluides; a. The conversion length between attractor and collector. b. The corona current of Emitter. c. The flow velocity of working fluids. d. Load resistance. This results are as follows; 1) There in a critical value in conversion length for its maximum power output. 2) Power output increases almost linearly with corona current and flow velocity. 3) There is the critical value of load resistance producing a maximum power output. 4) Kerosene is known better working fluid than Methyl alcohol in this EHD generator.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.90-94
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employes active and reactive power control or frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employes a instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Futhermore, the proposed control scheme is verified through the simulation in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.176-181
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employs active and reactive power control of frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel-connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employees an instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Furthermore, the proposed control scheme is verified through the experiment in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.569-571
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• 2003

As a definition of NERC, Available Transfer Capability(ATC) is a measure of the transfer capability remaining in the physical transmission network for the future commercial activity. To calculate ATC, accurate and defensible TTC, CBM and TRM should be calculated in advance. In this paper, we propose a method to quantify TRM using probabilistic load flow based on the method of moment. Generation output, bus voltages, loads, and line outages are considered as complex random variables (CRV) to take into account for uncertainties related to the transmission network conditions. Probability Density Function (PDF) of line flow at the most limiting line is used to quantify TRM with the desired probabilistic margin. Suggested method is compared with the results from conventional CPF method and verified using 24 bus MRTS, and the suggested method based on PLF shows efficiency and flexibility for the quantification of TRM compared with the conventional method.

• Transactions on Electrical and Electronic Materials
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• 제15권1호
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• pp.12-15
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• 2014

At the moment of transformer energization by the supply voltage, a high current called transient inrush current, which may rise to ten times the transformer full load current, could be drawn by the primary winding. This paper discusses a microcontroller circuit with the intention of controlling and limiting the inrush current for a transformer, by the method of ramping up the supply voltage feeding to the transformer primary. Simulations and the experimental results show a significant reduction of inrush current, when the ramping up voltage is applied to the three-phase transformer load. The inrush current could be almost eliminated if the correct switching step rate is chosen.