• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1259-1261
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• 2003

The vehicle's heading angle determination is formulated and the proposed method based on geometry engages the magnetometer and the GPS. The resulting maximum determination accuracy of 0.3deg over the entire earth as a standard deviation is obtained for a magnetometer with measurement error of 1nT.

• 대한물리의학회지
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• 제9권1호
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• pp.63-68
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• 2014

PURPOSE: The purpose of this study was to examine the position changes with tilt table on autonomic nervous system using heart rate variability analysis. METHODS: Fourty healthy adult males volunteered in this study. The low frequency, high frequency and low frequency/high frequency ratio and mean heart rate, standard deviation of all normal R-R intervals, root mean square of successive differences, heart rate variability index were measured at the tilt table angle of $0^{\circ}$, $45^{\circ}$ and $90^{\circ}$ with pulsoximeter. Data were analyzed one-way ANOVA and LSD post hoc test. RESULTS: The mean heart rate, low frequency and low frequency/high frequency ratio increased significantly at higher angle of tilt table(p<.05). The root mean square of successive differences, heart rate variability index decreased significantly at lower angle of tilt table(p<.05). The standard deviation of all normal R-R intervals, high frequency decreased at higher angle of tilt table did not show significant difference. CONCLUSION: The symphathetic activity increased significantly at higher angle of tilt table. The parasymphathetic activity decreased at higher angle of tilt table, but the difference were not significant. The autonomic adaptation, balance and heart rate variability decreased significantly at higher angle of tilt table. Based on these results, in the treatment of patients with a change in posture precedence should be carefully treated. Further studies are necessary to determine the most safety and effective methods.

• 한국항공우주학회지
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• 제31권5호
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• pp.72-79
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• 2003

본 실험에서는 충돌형 F-O-O-F 형태인 분사기의 충돌각을 15, 20, 그리고 30도로 변화시켰으며, 혼합비(O/F 비)는 1.5부터 3.0까지 증가시키면서 분무특성을 살펴보았다. 실험결과, 분무의 가시화를 통해서 혼합비는 확산각에 큰 영향을 주지 않지만 수밀도에는 영향을 끼쳤으며, 충돌각과 환산각 사이에는 충돌각이 증가할수록 확산각이 증가하는 선형적인 실험 관계식이 있음을 알 수 있었고, 충돌각이 증가함에 따라 분무폭은 커지며. 액적들의 속도 분포와 표준편차, 그리고 SMD는 작아짐을 알 수 있었다. 또한, 액적의 크기분포를 살펴본 결과 Rosin-Rammler와 Upper-Limit 분포함수와 잘 일치하고 있음을 확인 할 수 있었다.

• 대한물리치료과학회지
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• 제18권4호
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• pp.73-79
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• 2011

Purpose : This study is to know how position change in high-heels affects sacral tilt angle. 15 healthy women aged 21.87(standard deviation=3.54) were tested. Method : Lumbar and sacral tilt angle was measured by radiography barefooted, and after 15 mins of application time, they were measured in the same way in high-heels. Result : There was not notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle. However, there was differences in change degree, which was measured by estimation data of [post-pre)/pre]${\times}$100. Conclusion : There was no notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle, but as there were differences in change degree, research about how women's lumbar change when heel height increases is needed.

• 대한기계학회논문집
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• 제12권6호
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• pp.1407-1414
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• 1988

본 연구에서는 저자들에 의해 이미 개발된 경계유선수정법에 의한 B-B 유동계 산을 통해 익열의 편차각을 계산하고 기존의 예측방법에 의한 결과와 비교 검토하여 압축성 및 3차원 비축대칭성의 효과를 검토하였다.

• 대한전기학회논문지:전력기술부문A
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• 제48권6호
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• pp.704-711
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• 1999

This paper presents a design of fuzzy power system stabilizer (FPSS) using adaptive evolutionary computation (AEC). We have proposed an adaptive evolutionary algorithm which uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations. FPSS shows better control performances than conventional power system stabilizer (CPSS) in three-phase fault with heavy load which is used when tuning FPSS. To show the robustness of the proposed FPSS, it is appliedto damp the low frequency oscillations caused by disturbances such as three-phase fault with normal and light load, the angle deviation of generator with normal and light load and the angle deviation of generator with heavy load. Proposed FPSS shows better robustness than CPSS.

• Journal of Electrical Engineering and Technology
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• 제1권1호
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• pp.16-22
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• 2006

Selective ground relays (SGRs) are useful fur distinguishing a faulted feeder from the sound feeders in ungrounded systems. However, they sometimes mis-operate due to human or device errors. Particularly, the reversed polarity of zero-sequence current transducers (ZCTs) is the most frequent cause of mis-operation. This paper presents a modified SGR for reducing the probability of mis-operations caused by the reversed polarity of ZCTs. The modification is achieved by introducing an adaptive time delay, which depends on the magnitude of the zero-sequence current and the phase angle deviation from the reference. The modified SGR was successfully demonstrated on a sample ungrounded system without mis-operation.

• 한국통신학회논문지
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• 제21권10호
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• pp.2731-2737
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• 1996

The effect of the birefringence existing in the Faraday rotator on the isolation and transmission properties of the isolator was investigated. To maintain isolation of 50dB, both the deviation of the transmission angle between input and output polarizers and the deviation of the Faraday ratation angle are permitted to .+-.0.18.deg. for birefringenceless isolator and to .+-.0.09.deg. for birefringent isolator. This means that the isolator possessing linear birefringence of 0.5.deg. requires 505 more accurage adjustment than that of no birefringence. We also simulated the characteristics of wavelength dependence for both the virefringent isolator and the birefringencelless isolator. It is also found that formward transmission loss doesn't varing much with small birefringence.

• 전기학회논문지P
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• 제50권3호
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• pp.101-108
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• 2001

Frequency is an important operating parameter of a power system. Electric power systems sustain transient frequency swings whenever the balance between generation and load does not no longer hold. To cope with this constraints, it requires an accurate and high speedy frequency deviation estimation technique and suitable adjustment to obtain the Power system energy balance. This paper describes a digital signal processing technique for measuring the operating frequency of a power system. The fundamental frequency component of 3-phase signal is first extracted by using an algorithm based on FIR filter. The rate change of the phase angle is used for estimation. To confirm the validity of the proposed algorithm, the simulation studies carried out on a typical 154KV double T/L system by using EMTP software. Some test results are presented in the paper.

• International Journal of Fluid Machinery and Systems
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• 제9권4호
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• pp.354-361
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• 2016

This study aims to identify aerodynamic characteristics of the ramp tab, a mechanical deflector, by conducting a non-combustive experiment using compressed air and supersonic flow test equipment. With the ramp tabs installed symmetrically and asymmetrically on the outlet of the supersonic nozzle, the structure of the flow field, the thrust spoilage, the thrust deviation angle, and the lift/drag coefficients were derived and analyzed. The results show that the asymmetrically-installed ramp tabs are advantageous relative to the symmetrically-installed tabs in terms of the performance of thrust vector control, thrust deviation angle, and lift coefficient.