• Nuclear Engineering and Technology
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• 제33권6호
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• pp.626-637
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• 2001

A series of study on energy dependence in chemiluminescence dosimetry with sugar and sorbite produced in two different countries was carried out administering a dose of 5 Gy to the samples at six different mean photon energies of 30, 50, 80, 130, 662 and 1250 keV. The results revealed distinct energy dependence of chemiluminescence(CL) output of sugar and sorbite. Although the energy dependence, in general, could be fitted by a polynomial of (os E, with I being radiation energy, up to cubic term, we reached a conclusion that the adoption of a fitting function, $y_{R}$$^{=a}$.(1-e $^{-b.logE}$)$^{c}$ +d, deduced from theoretical energy response curve calculated as the ratio of the mass energy absorption of the samples of interest to the soft tissue is more reasonable and rational. Herecoefficients $y_{R}$ is CL intensity, and a, b, c and d are constants to be determined in the fitting process. Energy dependence of relative sensitivities of one sample to the other, discrepancy in sensitivities of the samples from the two countries, and prominent grain size effect in Sorbitol were also shown.shown.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.804-805
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• 2006

Electric scroll-compressor drives are commonly used for e.g. home appliance cooling units. The recent development of hybrid cars with internal combustion engine in combination with electrical propulsion requires new solutions to be able to cool the passenger compartment of cars at stand-still. Both application areas demand efficient motor drives to reach good economy and efficient use of limited battery power as well as competitive volume/weight for a given output. The BLDC motor is a controllable and efficient solution. A major part of the motor is the soft-magnetic core. The powder based $Somaloy^{(R)}$ material shows high resistivity and induction as the result of engineered iron particles with in-organic coating. The unique features of compacted $Somaloy^{(R)}$ components can be utilized to enhance the shape and total volume of the BLDC motor with at least maintained efficiency compared to the use of traditional laminated steel sheet cores. A careful design of the $Somaloy^{(R)}$ components can also simplify assembly and positively influence the coil configuration. This study shows a comparison between a typical laminated BLDC motor and a redesigned, $Somaloy^{(R)}$ based version adapted for a scroll-compressor application.

• 전력전자학회논문지
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• 제15권6호
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• pp.432-440
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• 2010

본 논문에서는 단일 스위치를 사용한 LC 직렬 공진형 부스트 컨버터를 제안하였다. 제안하는 토폴로지는 별도의 보조 스위치의 추가 없이 일반 부스트 컨버터에 수동소자만을 추가하여 스위치 턴-온, 턴-오프 시 영전압 스위칭(ZVS; Zero Voltage Switching)을 수행한다. 이 토폴로지는 LC직렬 공진에 의해 스위치 오프 타임이 결정되므로, 스위치 온 타임을 가변하여 출력전압을 조절하는 온 타임 가변형 주파수 변조 기법으로 제어된다. 전류 도통 경로에 따라 제안된 회로의 동작 모드를 구분하였고, 제안된 컨버터의 동작모드와 특성은 수학적 해석과 시뮬레이션 및 실험을 통해서 검증하였다.

• Journal of Power Electronics
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• 제12권6호
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• pp.886-894
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• 2012

This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.

• 전력전자학회논문지
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• 제16권4호
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• pp.334-341
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• 2011

본 논문은 비상전원 공급장치를 위한 넓은 입력전압 범위를 갖는 DC/DC 컨버터를 제안하고 그 설계 및 제작에 대하여 기술한다. 컨버터의 입력전압은 30V~400V이며 출력전압은 48V로, 2단 구성의 컨버터를 제안한다. 제안된 컨버터는 벅부스트 컨버터와 소프트 스위칭 특성을 갖는 LLC 공진 컨버터로 구성되며 LLC공진 컨버터는 고정주파수로 동작하며 벅부스트 컨버터에서 제어동작을 수행하여 제어를 단순화한다. 모의실험을 통해 설계된 회로를 검증하고 실제 300W급의 세트를 제작하여 그 성능을 검증한다.

• 전력전자학회논문지
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• 제25권1호
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• pp.37-43
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• 2020

This study proposes a 7kW low-voltage DC-DC converter (LDC) using a coupled inductor (CI) for heavy hydrogen electric transport vehicles. The LDC uses a phase-shift manner for soft switching. SiC-MOSFET is used to reduce the loss of reverse recovery current through the use of a high switching frequency. LDC is require large transformer and inductor because of large output current. The size of transformer and inductor can be reduced by deviding the transformer and inductor into two pieces each. This work presents the experimental results of the proposed circuit.

• 로봇학회논문지
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• 제12권1호
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• pp.26-32
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• 2017

Previous shape sensors including bend sensors and optic fiber based sensors are widely used in various applications including goniometer and surgical robots. But theses sensors have large nonlinearity, limited in the range of sensing curvature, and sometimes are expensive. This study suggests a new concept of bend sensor using cable-conduit which consists of the outer sheath and the inner wire. The outer sheath is made of helical coil whose length of the central line changes as the sheath bends. This length change of the central line can be measured with the length change of the inner cable. The modeling and the experimental results show that the output signal of the proposed sensor is linearly related with the bend angle of the sheath with root mean square error of 5.3% of $450^{\circ}$ sensing range. Also the polynomial calibration of the sensor can decrease the root mean square error to 2.1% of the full sensing range.

• 전기학회논문지
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• 제61권1호
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• pp.57-63
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• 2012

A surfaced permanent magnet spherical motor is capable of operating as three degree of freedom that used for the joints of the robot's arm, leg, and eyes. Ongoing research like new concept is essential part of motor field, it will make a great contribution in the future the overall portion of the motor, is becoming expected. The author analysis torque characteristics in spherical motor with state of rotating and positioning. And future design direction is smaller motors with equivalent or higher output. Solutions as torque and efficiency improvements are selecting the core with special processing type like powder metallurgy materials. Their special characteristic is high permeability and low eddy current losses at high speed, so improved the torque and efficiency.

• 한국항공우주학회지
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• 제49권10호
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• pp.879-882
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• 2021

텔레메트리 표준은 전력 및 대역폭 효율이 우수한 SOQPSK-TG를 변조 기법으로, 복호 성능이 우수한 LDPC 부호를 오류 정정 부호로 채택하고 있다. SOQPSK-TG 송신기는 프리코더와 CPM 변조기로 구성되어 있는데 각각의 수신기를 따로 구현하는 것보다 트렐리스를 결합하여 하나의 비터비 복호기로 구현하면 수신 성능을 향상시킬 수 있는데 본 논문에서는 이 비터비 복호기를 소프트 메트릭 출력이 가능한 max-log-map 복호기로 대신하여 LDPC 부호화한 SOQPSK-TG의 수신성능을 평가하였다. AWGN 채널에서 컴퓨터 모의 실험한 결과 기존의 방식보다 약 0.7~0.8dB의 Eb/No 성능 이득이 있다.

• 로봇학회논문지
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• 제14권1호
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• pp.58-64
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• 2019

The paper proposes a stiffness measurement device composed of a measurement part including six indenters and a fixing part including four fixtures. The device is able to make simultaneously measurements of the stiffness of human arm. The six indenters make use of both position and force control schemes sequentially whenever needed. In addition, the loadcells and the digital encoders are attached to the indenters and electric motors, respectively, so that the data can be provided in real time. On the end of the indenter, two-axis potentiometer is attached in order to measure the angle difference between the applied force axis and the axis normal to the skin of human arm, and to convert the force measured on the loadcell into the actual applied force to skin. For this purpose, the mapping between the voltage output and the angle of potentiometer was obtained by fitting it for each axis. Ultimately, the measurement device was able to measure the stiffnesses of six regions of human arm.