• Proceedings of the KSR Conference
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• 2009.05b
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• pp.259-264
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• 2009

This paper proposes a real-time estimation of the boost inductance in a single-phase AC/DC parallel PWM converter for high-speed EMU. The estimation procedure of the boost inductance is only based on the variation of input current and the input AC voltage measurement. The estimated boost inductance is optimized by the least square method. This estimation technique can improve the performance of current controller and reduce the harmonics of the input current in the feed-forward controller. The validity of proposed technique is verified through the MATLAB SIMULINK simulation results.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.2
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• pp.33-38
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• 2002

High performance packages must have a minimum insertion loss and return loss. In this paper, we design a millimeter-wave ceramic package using LTCC (Low Temperature Cofired Ceramic) technology to satisfy excellent transmission characteristics and characterize in a frequency range from DC to 30 GHz using the FEM (Finite Element Method) calculation. From these calculation results, the designed feed-through structure achieved 0.32 dB, 16.8 dB of the insertion loss and the return loss at 30 GHz respectively. This designed ceramic package will be useful for MMIC (Monolithic Microwave Integrated Circuit) modules.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2227-2236
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• 2017

In order to solve the neutral-point voltage fluctuation problem of three-phase three-level T-type inverters (TPTLTIs), the unbalance characteristics of capacitor voltages under different switching states and the mechanism of neutral-point voltage fluctuation are revealed. Based on the mathematical model of a TPTLTI, a feed-forward voltage balancing control strategy of DC-link capacitor voltages error is proposed. The strategy generates a DC bias voltage using a capacitor voltage loop with a proportional integral (PI) controller. The proposed strategy can suppress the neutral-point voltage fluctuation effectively and improve the quality of output currents. The correctness of the theoretical analysis is verified through simulations. An experimental prototype of a TPTLTI based on Digital Signal Processor (DSP) is built. The feasibility and effectiveness of the proposed strategy is verified through experiment. The results from simulations and experiment match very well.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.181-184
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• 2002

본 논문에서는 600Hz 무선 LAN 시스템에 탑재를 위한 600㎓ 대역 전력증폭기 모듈을 개발 하였다. 600㎓ 대역 전력증폭기 모듈에 실장된 600㎓ 대역 전력증폭기 MMIC는 ETRI에서 설계 및 제작한 것으로 칩의 크기는 2.80 × 1.75㎟이며, on-wafer측정을 하여 얻은 결과는 동작 주파수 58~620Hz에서 소신호 이득은 12.4dB이고, 최대 소신호 이득은 59~60G보z에서 ISdB이며, 출력전력(Pldn)은 16.3~16.7dBm을 얻었다. 이와 같은 특성을 갖는 전력증폭기 MMIC를 사용하여 모듈을 제작하였으며, RF feed line을 위해 Rogers 사의 R03003 기판을 사용하였다. 모듈의 입출력은 동작 주파수 대역에 적합한 WRl5라는 waveguide 형태를 사용하였고, DC 바이어스 공급을 위해 3.5㎜ K-connector를 사용하였다 제작한 모듈의 크기는 40 × 30 × 15㎣이며, 최적의 성능을 얻고자 tuning bar를 상하로 이동하여 최적점을 찾았으며 나사로 고정하여 상태를 유지하도록 하였다. DC 바이어스 및 RF feed line과 칩의 연결은 본딩에 의한 인덕턴스를 최소화하기 위하여 3mil 두께의 리본 본딩을 하였다 전력증폭기 모듈을 측정한 결과, 동작주파수 600㎓ 대에서 소신호 이득은 6dB 이상, 입력 정합은 -lOdB 이하, 출력 정합은 -4dB 이하로 측정되었긴, 출력전력은 SdBm 이상으로 측정되었다. 동국대에서 제작한 600Hz 무선 LAN 시스템에 전력증폭기 모듈을 시스템 송신부에 탑재 시험한 결과, 동영상을 실시간으로 전송하는데 성공하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.912-916
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• 1999

The purpose of this study was to investigate the effect of saponin in the shoot of Aralia elata on serum lipid level and glucose in streptozotocin(STZ) induced diabetic rats. Sprague Dawley normal male rats weighing 70$\pm$5g were randomly assigned to normal(control group), crude saponin(S group), and shoot of Aralia elata(D group). Experimental diets have been fed for 6 weeks. STZ induced diabetic rats were classified to diabetic control(DC group) and crude saponin(DS group). Diabetic rats were experimentally induced by intravenous injection of STZ(65mg/kg of body weight) dissolved in citrate buffer(pH 4.5). DS group has been i.p. injected with crude saponin solved in phosphate buffer(pH 7.0, 10mg/100g body weight) and DC group fed for 10 days. Body weight decreased significantly in crude saponin group. Feed intakes and feed efficiency ratio were not significantly different among C, S, and D group. The crude saponin group has indicated the lowest values of serum total cholesterol, glucose, and triglyceride. However, the values of serum glucose and triglyceride were not significant. Insulin levels among the crude saponin group, the shoot powder group, and the control group were not significantly different. When STZ induced diabetic rats have i.p. injection of crude saponin, the crude saponin has reduced the serum glucose but it is not been significant.

• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.45-48
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• 2012

Feed-back type 3-axis flux-gate magnetometer using Co-based amorphous ribbon (Metglass$^{(R)}$2714A) was constructed in this work. Measuring range of magnetic field and frequency were ${\pm}100\;{\mu}T$ and dc~10 Hz respectively. For the interface to computer, microcontroller and 24 bit ADC (Analog to Digital Converter) were employed and resolution of digital output was 0.1 nT. Magnetometer noise of analog output was 5 pT/$\sqrt{Hz}$ at 1 Hz. Digital output of the magnetometer showed linearity of $1{\times}10^{-4}$ and the offset drift was smaller than 0.2 nT during 1 h.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.6 s.348
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• pp.53-61
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• 2006

In high speed flash type or pipelining type A/D Converter, the faster sampling frequency is, the more the effect of DC reference fluctuation is increased by clock feed-through and kick-back. When we measure A/D Converter, further, external noise increases reference voltage fluctuation. Thus reference fluctuation reduction circuit must be needed in high speed A/D converter. Conventional circuit simply uses capacitor but layout area is large and it's not efficient. In this paper, a reference fluctuation reduction circuit using transmission gate is proposed. In order to verify the proposed technique, we designed and manufactured 6bit 2GSPS CMOS A/D converter. The A/D converter is based on 0.18um 1-poly 5-metal N-well CMOS technology, and it consumes 145mW at 1.8V power supply. It occupies chip area of $977um\times1040um$. Experimental result shows that SNDR is 36.25 dB and INL/DNL ${\pm}0.5LSB$ when sampling frequency is 2GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.128-135
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• 2004

The author present a modified multi-loop algorithm including feedforward for controlling a 55kW step down chopper in the power supply of Maglev. The control law for the duty cycle consists of three terms. The first is the feedforward term. which compensates for variations in the input voltaga. The second term consists of the difference between the slowly moving inductor current and output current. The third term consists of proportional and integral terms involving the perturbation in the output voltage. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.525-528
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• 2002

The proposed EMC filter composed with feed-through capacitors and ferrite beads of high permeability was prepared which satisfy the EMC standard for a wide-band noise signal in the frequence of 10 MHz to 1.5 GHz in power supply line. The optimum structure of ferrite bead was found by calculating the load effect of ferrite beads. As a result, the filter showed excellent differential- and common-mode noises filtering characteristics above 30dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8GHz.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.2
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• pp.146-153
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• 2009

This study was conducted to examine the effects of fruits and stems of Opuntia ficus-indica var. saboten Makino on water intake, feed intake, body weight, blood glucose level and glucose tolerance in streptozotocin (STZ)-induced diabetic rats. Forty Sprague-Dawley male rats were divided into non-diabetic control (NC), diabetic control (DC), 8% Opuntia fruit (DOF), 5% Opuntia stem (DO-5) and 10% Opuntia stem (DO-10) groups. Fruits and stems of Opuntia ficus-indica were freeze-dried and ground before use in the experiment. Animals were fed experimental diet for 3 weeks. DOF, DO-5 and DO-10 groups showed lower water and feed intake as well as less body weight loss than DC group. The fasting blood glucose levels were 100 mg/dL for NC and 379 mg/dL for DC. Fasting glucose level of DOF was a significantly low level of 28% (p<0.05), whereas DO-5 and DO-10 had a decrease of 5% and 9% compared to DC. As for the glucose tolerance test, the highest blood glucose levels for NC and DC-10 group were observed at 30 minutes after glucose injection while those of DOF and DO-5 groups were after 60 minutes. DOF and DO-5 plasma insulin level improved. Plasma total cholesterol, triglyceride, non-esterified fatty acid (NEFA) and LDL-cholesterol concentrations were also lower in DOF, DO-5 and DO-10 groups, although HDL-cholesterol level was only slightly affected by experimental diets compared to DC. These results suggest that the feeding of Opuntia ficus-indica fruits and stems improved blood glucose and lipid metabolism in STZ-induced diabetic rats.