• 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.

• 천문학회지
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• 제33권1호
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• pp.29-36
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• 2000

We developed a Monte Carlo code that describes the resonant Ly$\alpha$ line transfer in an optically thick, dusty, and static medium. The code was tested against the analytic solution derived by Neufeld (1990). We explain the line transfer mechanism by tracing histories of photons in the medium. We find that photons experiences a series of wing scatterings at the moment of thier escape from the medium, during which polarization may develop. We examined the amount of dust extinction for a wide range of dust abundances, which are compared with the analytic solution. Brief discussions on the astrophysical application of our work are presented.

• 문화기술의 융합
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• 제4권4호
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• pp.101-105
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• 2018

본 연구의 목적은 키네시오 테이핑 적용 전과 적용 즉시의 앞쪽 머리자세에 미치는 영향을 평가하는 것이었다. 강원도 문막에서 대학생(18명)을 키네시오테이핑 적용 전과 적용 즉시에 Exbody 장비로 신체정렬을 평가하여 Plumb Line, CVA, PCMT를 측정하였다. 이 연구의 결과는 키네시오 테이핑 적용 즉시에 Plumb Line, CVA, PCMT 모두 키네시오 테이핑 적용 전과 비교하여 통계학적으로 유의한 결과로 나타났다(p <.05). 따라서 키네시오 테이핑 적용 즉시부터 앞쪽머리자세의 개선되는 효과를 확인할 수 있었다.

• 한국항해학회지
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• 제11권2호
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• pp.61-72
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• 1987

When a ship is running in following seas, the encounter frequency is reduced to a very low one. In that case broaching, surfiding and capsizing phenomena are most likely to occur due to wave exciting forces acting on a ship in following seas. In this paper, the emphasis is mainly laid upon transverse stability of ships following seas, which is related to capszing phenomenon. The authors take the case that ship speed is equal to the wave celerity, i.e., the encounter frequency is zero. Hydrostatic force and moment due to Froude-Krylov hypothesis are calculated by line intergral method. Transverse stability is evaluated from hydrostatic force and moment. Through the application of present calculation method to box-shaped vessel, it is confirmed that the transversestability of a vessel can be reduced to critical level at wave crest.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.49-54
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• 2011

Carbody bolster must be a strong structural member of the underframe because it is in the direct line of weight transmission. On the other hand, carbody bolster is a heavy member that occupied about 20~25% in the weight of underframe. In order to reduce the weight of carbody bolster, we study the design factors such as bending stiffness, bending strength and deformation according to the change of carbody bolster's second moment of area. And we investigate the design factors of a total of 10 species of existing rail vehicles. The results of this study can be used as practicable method in designing carbody bolster in the future.

• 한국자동차공학회논문집
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• 제6권2호
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• pp.1-11
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• 1998

The 4WS system is usually developed to improve the maneuverability at low speed and the straight line stability at high speed, but it is found to have the severe understeer characteristics at high speed. Therefore a 4WS vehicle requires to turn the steering wheel much more than a 2WS vehicle at high speeds even a driver goes through the same curved road. In this study, to enhance the cornering performance of the 4WS vehicle at high speed, a DYC 4WS system is proposed based on the nonlinear 4WS system and direct yaw moment control system. Especially the proposed DYC 4WS system is able to realize a zero side slip angle for vehicles and a cornering performance similar to the 2WS vehicle at high speed.

• Journal of Power Electronics
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• 제16권4호
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• pp.1387-1395
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• 2016

A method for the identification of mechanical parameters based on integral calculation is presented. Both the moment of inertia and the friction constant are identified by the method developed here, which is based on well-known mechanical differential equations. The mechanical system under test is excited according to a pre-determined low-frequency sinusoidal motion, minimizing the distortion, and increasing the accuracy of the results. The parameters are identified using integral calculation, increasing the robustness of the results against measurement noise. Experimental data are supported by simulation, confirming the effectiveness of the proposed technique. The performance improvements shown here are of use in the design of speed and position controllers and observers. Owing to its simplicity, this method can be readily applied to commercial inverter products.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.101-116
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• 2002

Modern vehicles require a high degree of refinement, including good driveability to meet customer demands. Vehicle driveability, which becomes a key decisive factor for marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore, Engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes analysis procedures using a mathematical model which has been developed to simulate spark timing control logic. Inertia mass moment, stiffness and damping coefficient of engine and drive train were simulated to analyze the effect of parameters which were related vehicle dynamic behavior. Inertia mass moment of engine and stiffness of drive line were shown key factors for the shuffle characteristics. It was found that torque increase rate, torque reduction rate and torque recovery timing and rate influenced the shuffle characteristics at the tip-in condition for the given system in this study.

• Journal of Biosystems Engineering
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• 제27권5호
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• pp.371-380
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• 2002

The objectives of this study were to analyze gear rattle in a power drive line using its dynamic model and to derive design guidelines to eliminate it. A 72 degrees of freedom model of power driveline of an agricultural tractor was developed and proved to be valid fer predicting the collision characteristics of gears in mesh, which may determine whether or not the gear rattle will occur. Using the model the effects on the rattle of drag torque, backlash, mass moment of inertia, transmitting torque were analyzed. Increasing drag torque or decreasing mass moment of inertia reduced gear rattle. The gears transmitting power do not develop rattles. It was also found that a large amount of rattle is likely to be developed by the change gears placed at the end of idle shafts. Increasing the drag torque to such change gears may be the most effective way of reducing the gear rattle in a tractor driveline.

• 한국소음진동공학회논문집
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• 제12권2호
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• pp.108-115
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• 2002

The excitation forces from the periodical firing pressure in cylinder and the rotating crank mechanism cause lots of vibration problems in diesel engines. In this Paper. the computational program for predicting the excitation force is developed and applied to 4-stroke In-line engines. The crank angle is also optimized to reduce the first and second order moment produced by engines. Compared to the conventional uniform crank angle, about 70 % of the first order horizontal and vertical moment can be reduced by re-designing the crank angle non-uniformly.