• 한국운동역학회지
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• 제22권2호
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• pp.131-140
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• 2012

This study was to investigate the relationship between the distance and projection factors, angle factors of javelin in women's javelin throwing. The data were collected in the 2011 National Sports Festivals for 11 players. Three-Dimensional motion analysis using a system of 4 video cameras at a sampling frequency of 60 fields/s was performed for this study. The factors of release conditions calculated using Matlab 2009a program. The statical analysis on the records(n=42) included mean and standard deviation of the mean(SD), Pearson's product moment correlation coefficient(SPSS Version 16.0 for Windows). There was a statistically significant positive relationship between the records and release velocity(r=.866, p<.01), height(r=.433, p<.01) and height rate(r=.340, p<.05). The attitude angle, release angle, and attack angle showed not a statistically significant relationship between the records. The medial-lateral tilt angle of javelin showed not a statistically significant relationship between the records, but the yaw angle of javelin(r=.549, p<.01) showed a statistically significant positive relationship between the records.

• 한국정밀공학회지
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• 제20권5호
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• pp.82-91
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• 2003

Vehicle dynamics control (VDC) has been a breakthrough and become a new terminology for the safety of a driver and improvement of vehicle handling. This paper examines the usefulness of a brake steer system (BSS), which uses differential brake forces for steering intervention in the context of VDC, In order to help the car to turn, a yaw moment can be achieved by altering the left/right and front/rear brake distribution. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. An 8-DOF non-linear vehicle model including STI tire model will be validated using the equations of motion of the vehicle, and the non-linear vehicle dynamics. Since fuzzy logic can consider the nonlinear effect of vehicle modeling, fuzzy controller is designed to explore BSS feasibility, by modifying the brake distribution through the control of the yaw rate of the vehicle. The control strategies developed will be tested by simulation of a variety of situation; the possibility of VDC using BSS is verified in this paper.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.91-98
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• 2017

Performance of a low speed axial compressor is enhanced through a proper configuration of blade row tip injection and casing treatment of groove type. Air injectors were mounted evenly spaced upstream of the blade row within the casing groove and were all aligned parallel to the compressor axis. The groove, which covers all the blade tip chord length, extends all-round the casing circumference. Method of investigation is based on solution of the unsteady form of the Navier-Stokes equations utilizing $k-{\omega}$ SST turbulence model. Extensive parametric studies have been carried out to explore effects of injectors' flow momentums and yaw angles on compressor performance, while being run at different throttle valve setting. Emphasis has been focused on situations near to stall condition. Unsteady numerical analyses for untreated casing and no-injection case for near stall condition provided to discover two well-known criteria for spike stall inception, i.e., blade leading edge spillage and trailing edge back-flow. Final results showed that with only 6 injectors mounted axially in the casing groove and at yaw angle of 15 degrees opposite the direction of the blade row rotation, with a total mass flow rate of only 0.5% of the compressor main flow, surprisingly, the stall margin improves by 15.5%.

• 제어로봇시스템학회논문지
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• 제16권8호
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• pp.735-743
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• 2010

A new Fuzzy sliding mode controller is proposed to improve the cornering performance of the four wheel hybrid vehicles. The Fuzzy sliding mode control is applied for the control of rear motor and EHB (Electro-Hydraulic Brake) to improve the cornering performance. The modeling of the automobile is simplified that each of the two wheels is modeled as two degrees of freedom object and the friction coefficient between the wheel and the ground is assumed to be constant. The output of the Fuzzy sliding mode algorithm is the direct yaw moment for the rear wheels, which compensates for the slip angle. Through the simulations using ADAMS and MATLAB Simulink, the cornering performance of the proposed algorithm is compared to the conventional PID to show the superiority of the proposed algorithm. In the simulation experiments, the J-Turn and single lane change are used for each of the Fuzzy sliding mode algorithm and PID controller with the optimal gains which are tuned empirically.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.47-58
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• 2009

In this study, a Hardware-In-the-Loop (HIL) simulator using thrusters is developed to validate the spacecraft attitude system. To control the attitude of the simulator, eight cold gas thrusters are aligned with roll, pitch and yaw axis. Also linear actuators are applied to the HIL simulator for automatic mass balancing to compensate the center of mass offset from the center of rotation. The HIL simulator consists of an embedded computer (Onboard PC) for simulator system control, a wireless adapter for wireless network, a rate gyro sensor to measure 3-axis attitude of the simulator, an inclinometer to measure horizontal attitude, and a battery set to supply power for the simulator independently. For the performance test of the HIL simulator, a bang-bang controller and Pulse-Width Pulse-Frequency (PWPF) modulator are evaluated successfully. The maneuver of 68 deg. in yaw axis is tested for the comparison of the both controllers. The settling time of the bang -bang controller is faster than that of the PWPF modulator by six seconds in the experiment. The required fuel of the PWPF modulator is used as much as 51% of bang-bang controller in the experiment. Overall, the HIL simulator is appropriately developed to validate the control algorithms using thrusters.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.190-198
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• 1997

Traction control systems are used to prevent the wheel slippage and to maximize the traction force. A new scheme of controlling the wheel slip during cornering by varying the slip ration as a function of the slip angle is proposed and dynamically simulated with the model of a front wheel driven passenger vehicle. Simulation results show that the proposed scheme is superior to conventional ones based on the fixed slip ratio during cornering and lane changes.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.24.4-25
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• 2008

Limb scanning measurements of the O2 (0-0) Atmospheric band emission by the TIDI instrument aboard the TIMED satellite during 2003-2005 are analyzed to examine the tidal effects on their vertical emission rate according to the solar and geomagnetic activities. The data are restricted at latitudes $60^{\circ}S-60^{\circ}N$ to avoid the contributions by the auroral emission. The variation of the vertical emission rate in latitude and local time is summarized in the yaw periods. The vertical emission profiles of the O2 (0-0) Atmospheric band nightglow averaged in the $10^{\circ}$ latitude range are investigated. The result shows the inverse relationship between the peak emission height and the integrated brightness.

• 한국ITS학회 논문지
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• 제7권3호
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• pp.15-28
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• 2008

교통사고의 여러 요인 중 대부분의 사고가 운전자의 특성과 운전행태가 교통사고에 가장 큰 영향을 미치고 있음을 2006년 경찰청 사고건수 자료를 통하여 파악 할 수 있다. 현재 교통사고 감소 및 안전운전에 대한 사회적 요구에 부응하기 위하여 디지털 주행기록계, 차량용 블랙박스 등이 출시되고 있으나 위험운전 유형에 대한 명확한 분류가 이루어지지 않아 그 효율성이 매우 떨어지고 있다. 이에 본 연구에서는 운전자로부터 발생할 수 있는 위험운전 유형을 발생 원인을 중심으로 7가지의 대분류와 이를 좀더 구체화한 16가지의 소분류로 재정의 하였다. 또한 재정의 된 위험운전 유형에 대한 분석을 위하여 차량거동상태에 따른 모든 차량데이터를 취득 분석할 수 있는 Data-logger를 개발하였다. 개발된 Data-logger는 시험차량으로부터 실시간으로 전송되는 가속, 감속, Yaw rate, 영상데이터 등을 이용하여 운전자로부터 발생 할 수 있는 위험운전 유형을 검출하여 실시간으로 위험운전에 대한 경보를 제공할 수 있는 시스템 및 향후 안전운전 관리 시스템을 구축할 수 있다.

• 에너지공학
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• 제19권3호
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• pp.156-162
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• 2010

국내 미분탄 보일러의 로내 공기량 공급에 따른 연소특성 분석을 위한 3차원 전산해석 연구를 수행하였다. 보일러 연소해석 해석 결과의 건전성 검증을 위하여 보일러 출구, 즉 절탄기 후단에서의 가스 온도,$O_2$, NO, SOx 농도를 발전소의 실제 운전데이터와 비교하였다. 검증된 해석 결과를 기준조건으로 SOFA(Separated Over Fire Air)와 CCOFA(Closed Coupled Over Fire Air)에서의 연소 공기량을 변화시킨 경우 보일러내 NOx와 가스 온도 분포를 중심으로 각각의 경우를 비교하였다. 본 연구를 통하여 CCOFA보다는 SOFA 공기량의 변화에 따라 NOx 농도의 민감도가 더 큰 것을 알 수 있었으며 대류 전열부의 전열관군에서의 온도 분포가 다르게 나타나고 있어 가스온도 편차 방지를 위한 연소조정이 필요함을 알 수 있었다.

• 제어로봇시스템학회논문지
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• 제13권1호
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• pp.6-14
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• 2007

Modem version of supersonic jet fighter aircraft must have been guaranteed appropriate controllability and stability in HAoA(High Angle of Attack). Limit value of aircraft entering into the departure in HAoA is related to aircraft configuration design. But, the control law such as AoA and yaw-rate limiter is implemented in digital Fly-By-Wire flight control system of supersonic jet fighter to guarantee the aircraft's safety in HAoA. The HAoA flight control law have two parts, one is control law of departure prevention and the other is control law of departure recovery support. The control laws of departure prevention for advanced jet trainer consist AoA limiter, roll command limiter and rudder fader. The control laws of departure recovery support are consist yaw-rate limiter and MPO(Manual Pitch Override) mode. The guideline of pitch rocking using MPO mode is simple, but operating skill of pitch rocking is very difficult by the pilot with inexperience of departure situation. This paper addresses the design and validation of APR(Automatic Pitch Rocker) control law instead of MPO in order to automatic recovery without manual pitch rocking by the pilot. And, recovery characteristic with APR verifies by the nonlinear analysis and pilot evaluation.