• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.998-1004
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• 1987

This paper describes the design theory of a weakly-coupled Tap-off with high density of coupling intervals for CATV ynd/or MyTV systyms, by yhich the degree of freedom in design and density of coupling intervals are significantly increased compared with the intrinsic one. It is also described how a 2-way power divider(Tap-off) is constructed in the generalized type. Furtuermore, the practical measurements of the frequency characteristics for a fabricated circuit show very good agreements with theoretical results, and, hence, the validity of the proposed design and analyses methods are confirmed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.272-278
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• 2008

This paper investigated the a-si:H gate driver with the stepwise gate signal. In 1-chip type mobile LCD application the stepwise gate signal for low power consumption can be used by adding simple switching circuit. The power consumption of the a-Si:H gate driver can be decreased by employing the stepwise gate signal in the conventional circuit. In conventional one, the effect of stepwise gate signal can decrease slew rate and increase the fluctuation of gate-off state voltage, In order to increase the slew rate and decrease the gate off state fluctuation, we proposed a new a-Si:H TFT gate driver circuit. The simulation data of the new circuit show that the slew rate and the gate-off state fluctuation are improved, so the circuit can work reliably.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.10
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• pp.399-406
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• 1985

In this paper transparent PLZT ceramics for the composition of 9/65/35 (La/Zr/Ti ) are fabricated using hotpress and the possibility of application to optical shutter is examined by obtaining the On-Off characteristics of specimens. The ferroelectric E-P hysteresis loop exhibits slim loop suitable for the quadratic electrooptic effect. Measurements of the electrooptic effect show that specimens have the quadratic electrooptic effect but the light intensities as functions of electric field exhibit butterfly type hysteresis curves because of its slightly large saturation remanent polarization and coercive field. On-Off characteristics are obtained by electric fields of-6 kv/cm and +2kv/cm. As a result of experiments, 9/65/35 PLZT ceramics can be applied to optical shutter but construction with other composition which has more slim hysteresis loop is desired for obtaining the Off state by zero electric field.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.188-195
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• 2000

This study was conducted to develop the mathematical model and the computer simulation program(TPPMWV) for predicting the tractive performance of off-road wheeled vehicles operated on various soil conditions. The model takes into account main design parameters of a wheeled vehicle, including the radius and width of front and rear tires, the weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 5.25%(4WD) AND 9.42%(2WD)for two different driving types, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.289-295
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• 2008

In this paper, we designed the off-line PWM(Pulse width modulation) control IC for flyback type power converter to reduce the standby power consumption. In normal state, this off-line PWM IC generates the output pulse with $40\sim60kHz$ frequency and duty ratio of $20\sim88%$. When SMPS operates in standby mode, this IC generates the output pulse with 33kHz frequency and duty ratio of 1 %. SPICE simulation was performed to verify the standby power consumption of the power converter with designed of-line PWM IC. Power converter with designed off-line PWM IC consumes less than 0.3W when it operates in standby mode condition.

• Ocean Systems Engineering
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• v.7 no.2
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• pp.89-106
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• 2017

The study explores a novel design of wave energy converter (WEC) that utilizes the interaction between an inside heaving vertical cylinder with an outside fixed hollow cylinder. This design originates from the oscillating water column (OWC) type WEC but replaces the pneumatic power take off (PTO) through the Wells turbine with the hydrodynamic PTO through the inside heaving cylinder. To effectively evaluate the maximum power output, the system has been modeled in the hydrodynamic software AQWA (developed by ANSYS Inc) that has accumulated extensive offshore industry users. Ranges of the PTO parameters have been examined to make sure that proper linear damping can be implemented to simulate the PTO force. Comparing the efficiency of the pneumatic PTO with the hydrodynamic PTO, it appears that the hydrodynamic PTO is more promising than the traditional Wells turbine for an OWC system.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.206-211
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• 2002

FPSO(FSO)같은 대형 구조물을 육상에서 건조하여 LOAD-OUT 과 FLOAT-OFF 를 수행하기 위해 한 척의 반 잠수바지로는 불가능하였다. 그래서 두 척의 반 잠수 식 바지를 HINGED TYPE 이 아닌 FIXED TYEP 으로 연결하였고 이에 따라 FLOAT OFF 시에 고려하여야 할 사항 중에서 횡강도 및 바지가 잠수 할 시점의 STABILITY 가 중요시되었다. 또한 FSO 가 잠수바지로부터 떨어져 나올 시점에서, STABILITY CASING 과 FSO 와의 충돌가능성도 고려하여야 할 사항이다. 이 논문에서는 안정성 측면에서의 반 잠수식 바지의 BALLASTING과 충돌방지 차원에서 전체적인 OPERATION에 대하여 언급하였다.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1629-1631
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• 2003

고전압 대전류 펄스파워에 사용되는 스위치는 여러 종류가 사용되고 있는데, 커페시터에 저장된 초기의 전자 에너지를 시공적으로 압축하여 수ns ${\sim}$ 수ms의 짧은 시간안에 고출력을 발생시키기 위해서는 펄스파워 장치에 사용되는 커패시터, 인덕터, 저항, 스위치등 회로 소자들의 임피이던스가 작아야 할 필요성이 대두 된다. 따라서 Inverse Pinch Switch(IPS)는 이런 조건을 만족시킬수 있는 스위치로서 각광을 받고 있다. 본 논문에서는 전기트리거형 IPS의 금속 전극부와 절연 ceramic를 brazing하여 sealed off type의 스위치의 제작 과정과 특성을 연구 하였다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.5-6
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• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.121-126
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• 1991

The knife-edge scanning type OTF measuring equipment is improved to enhance the accuracy in off-axis OTF measurement and the accuracy of this equipment of evaluated by measuring the OTF of 50 mm plano-convex standard lens developed by SIRA group. Measured MTF values of the standard lens are in good agreement with SIRA results within $\pm$0.02 on axis and % $\pm$0.03 off-axis in 0-100 clmm frequency range except only a few spatial frequencies. Measured PTF values are good agreement with SIRA results within $\pm$$5^{\circ}$.