• 한국통신학회논문지
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• 제12권4호
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• pp.347-356
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• 1987

本 論文에서는 高速 光 디지털 傳送시스템과 같은 高速 unipolar 信號 傳送시스템에 適合한 새로운 mBIZ 傳送路符號를 提案하였다. mBIZ符號는 情報信號系列 傳送速度를 $\frac{(m+1)}{m}$ 만큼 速度變換한 後 m 비트마다 補助 서어비스 비트 하나를 揷入한 信號系列과 出力傳送路符號系列의 한 비트를 遲延시킨 信號系列을 Exclusive NOR하여 符號化하기 때문에 redundancy를 줄일 수 있을 뿐만 아니라 復號回路 역시 간단하게 構成할 수 있다. mBIZ符號는 回符號連積數를 (m+1)비트 이내로 抑壓할 수 있으며 傳送路符號系列의 마크率이 1/2이기 때문에 電力 스펙트럼에 存在하는 高低周波 成分들을 抑壓할 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.780-785
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• 2003

Recently the trends in information storage devices need small size, mobility, high capacity, and low power consumption etc. To satisfy those, the development of high performance actuator is an important issue. Compared with general linear actuator for optical disk drive, swingarm type rotary actuator is suitable to design in small form factor and has fast access time for random access. Swingarm actuator is designed considering the structural problem and the actuating force of VCM(Voice Coil Motor). The increase of mass caused by optical components makes vibration problems of swing-arm, therefore resonance frequency should be increased and inertia has to be reduced. ANSYS FEM tool is employed in optimizing swingarm. The VCM is designed using 3-D electro-magnetic analysis, and parameters of magnetic circuit are determined to matte large flux density. The large flux density enables to achieve low power consumption. VCM holder is designed to get the mass balance of total actuator and this balance reduces the magnitude of critical mode relative to pivot bearing, It is expected that swingarm type rotary actuator designed by this method is available to variable type of micro optical disk drives.

• 한국컴퓨터산업학회논문지
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• 제2권7호
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• pp.895-904
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• 2001

본 연구에서는 능동 더블 밸런스 혼합기를 사용하기 때문에 이득을 높일 수 있지만 IIP3가 낮은 수신 시스템 I과 이득이 낮고 IIP3가 높은 수동 더블 밸런스 혼합기와 낮은 이득을 높이기 위한 중간 주파 증폭기로 구성된 수신 시스템II을 구성하여 수신 파라미터를 시험한 결과, 수신 시스템 I의 전체 잡음지수는 6.4382 dB이고 이득은 53.5dB, 제 3고조파 차단점은 -6.6352dB m이었다. 또한 수신 시스템II에서 전체 잡음지수는 9.70672dB이고 이득은 41dB, 제 3고조파 차단점은 3.66729dB m이었다.

• Journal of electromagnetic engineering and science
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• 제9권2호
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• pp.98-104
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• 2009

An InGaP/GaAs MMIC LC VCO designed with Harmonic Noise Frequency Filtering(HNFF) technique is presented. In this VCO, internal inductance is found to lower the phase noise, based on an analytic understanding of phase noise. This VCO directly drives the on-chip double balanced mixer to convert RF carrier to IF frequency through local oscillator. Furthermore, final power performance is improved by output amplifier. This paper presents the design for a 1.721 GHz enhanced LC VCO, high power double balance mixer, and output amplifier that have been designed to optimize low phase noise and high output power. The presented asymmetric inductance tank(AIT) VCO exhibited a phase noise of -133.96 dBc/Hz at 1 MHz offset and a tuning range from 1.46 GHz to 1.721 GHz. In measurement, on-chip down-converter shows a third-order input intercept point(IIP3) of 12.55 dBm, a third-order output intercept point(OIP3) of 21.45 dBm, an RF return loss of -31 dB, and an IF return loss of -26 dB. The RF-IF isolation is -57 dB. Also, a conversion gain is 8.9 dB through output amplifier. The total on-chip down-converter is implanted in 2.56${\times}$1.07 mm$^2$ of chip area.

• 식품보건융합연구
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• 제6권6호
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• pp.9-15
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• 2020

In this study, we want to investigate the nutrition knowledge, eating habits, and food intake patterns of adults who have a strong preference for sugary snacks or sugary drinks. In this study, 83 students, or 33.1% of the 267 adults, were found to belong to the sugary food group, and the results of the survey were as follows. In terms of the level of eating habits, both male and female adults see significant differences among the groups. In the question of the regularity of the three meals, the quality of breakfast, the balance of meals, the level of consumption of green vegetables, meat, fish and milk, the number of sugars was low, and the number of sugars, instant foods, ham and sausages was high. In terms of nutritional knowledge, both male and female adults had a low number of sugary foods, and there were significant differences among the groups. In terms of the frequency of food intake, the frequency of eating rice and mixed grain rice was low, and the frequency of eating ramen and bread was high.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.87-90
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• 2005

High-efficiency switched-mode circuits such as the class-E amplifier are well-known in the MHz frequency range. The class-E amplifier is a type of switching mode amplifier offering very high efficiency approaching 100%. In this paper of the class-E amplifier by using pHEMT device, the design has been done theoretically and experimentally, with simulation by using the harmonic balance method using circuit simulator. The amplifier using microstrip circuit and the pHEMT demonstrate 66% power-added- efficiency (PAE) at 2.4GHz with 17.6dBm of output power.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1632-1642
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• 2014

This paper presents an interleaved resonant converter to reduce the voltage stress of power MOSFETs and achieve high circuit efficiency. Two half-bridge converters are connected in series at high voltage side to limit MOSFETs at $V_{in}/2$ voltage stress. Flying capacitor is used between two series half-bridge converters to balance two input capacitor voltages in each switching cycle. Variable switching frequency scheme is used to control the output voltage. The resonant circuit is operated at the inductive load. Thus, the input current of the resonant circuit is lagging to the fundamental input voltage. Power MOSFETs can be turn on under zero voltage switching. Two resonant circuits are connected in parallel to reduce the current stress of transformer windings and rectifier diodes at low voltage side. Interleaved pulse-width modulation is adopted to decrease the output ripple current. Finally, experiments are presented to demonstrate the performance of the proposed converter.

• 대한한의학회지
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• 제29권2호
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• pp.107-115
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• 2008

Objectives: The objective of this study was to assess the effects of acupuncture applied at PC6 and SP4 points on heart rate variability (HRV) in normal subjects under mental stress Methods: 24 healthy male subjects were recruited and randomized to a treatment group (12 subjects) or a control group (12 subjects). Both groups performed a mental arithmetic stress test and then acupuncture needles were inserted on PC6 and SP4 for the study group. In the control group, they took sham acupuncture as a control. Heart rate variability (HRV) was measured during the whole study period by FM-150 (digital Holter ECG recorder). Results: In the both groups, low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) was significantly increased after mental stress. Acupuncture induced significant decrease in low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) which were increased after mental stress test. But sham acupuncture induced no changes. Results: In both groups, low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) significantly increased after mental stress. Acupuncture induced significant decrease in low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) which increased after mental stress test. In contrast, sham acupuncture induced no changes. Conclusions: Acupuncture on PC6 and SP4 could be useful to decrease sympathetic activity and balance autonomic nervous system for those who are under stress.

• 한국지역사회생활과학회지
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• 제16권4호
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• pp.115-123
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• 2005

This study was performed to compare dietary behaviors based on residence types of female college students. Self reports on dietary behavior and one-day dietary records were obtained from 227 female college students using anonymous questionnaires. The mean age of the subjects was $20.4{\pm}1.43$, and the height and weight were $162.5{\pm}4.8cm$ and $52.3{\pm}7.9kg$, respectively, The dietary behavior of female college students was inadequate, showing indifference to dietary balance, irregularity of meals, skipping breakfast, and high experience of drinking. One-day dietary records were obtained from 24k recall methods also showed a high number registering skipped meal status ($55.3\%$) and less diverse food intake (DVS, 12.5; DDS, 3.93). The students in self boarding residence were especially more likely not to eat properly and their dietary behaviors were found to be significantly poor. In the case of home residence, food intake frequency scores for milk and dairy products, fruits, and fishes were significantly higher, however the students in self boarding residences showed high food intake frequency scores in salted food, retort food, canned food, and especially instant ramyun. Therefore, more attention needs to be given to them to recognize the problems in their own dietary behaviors and more practical nutritional supports, like developing a menu for breakfast in college cafeterias, would be helpful to improve their dietary choices.

• 한방안이비인후피부과학회지
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• 제21권2호
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• pp.142-153
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• 2008

Objective : Etiologically, stress is a important factor to immune system and skin disease. Human body is controled to keep his homeostasis from stress by autonomic nerve system. So we investigated autonomic nerve balance and stress level of patients with skin disease by heart rate variability(HRV) test. Research Methods and Procedures : Fifty two patient(from 15 years old to 35 years old) who visited Dept. of Oriental medical Dermatology, Kyunghee university at first and had an examination by HRV test, were selected as the subject of our study. We checked items of HRV test(such as SDNN, RMSSD, VLF, LF, HF, TP, norm-LF, norm-HF, LF/HF ratio, LnHF and LnHF), and analyzed time and frequency domain by sex, age, onset, color on end of patient's tongue, sweating and sleep condition. Results and Conclusion : Men showed significant higher SDNN, RMSSD, LF, norm-LF, norm-HF, LF/HF ratio, LnLF and LnHF than women(p <0.05). Patients who were attacked by skin disease within 6 months, showed significant higher TP and VLF than over 6 months(p <0.05). Patients with normal color on the end of their tongue showed significant higher TP and VLF than with flare color. We analyzed correlation to color on the end of tongue and RMSSD. Prevalence risk(RMSSD <20ms) in the case of normal color on the end of tongue was 5 times as high as in the case of flare color(p <0.1). And we analyzed correlation to age and LF/HF ratio. Prevalence risk(LF/HF ratio <1) of patients from 15 years old to 25 years old was 1.467 times as high as from 26 years old to 35 years old(p <0.1).