• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.512-514
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• 2008

In this paper, a new electromagnetic circuit is proposed for an optical pickup actuator with high sensitivity. Contrary to those of conventional actuators, the proposed circuit has two focusing coils which are diagonally placed at the front and rear of a moving part. The configuration which makes the effective length of the focusing coil longer and the moving part lighter, is helpful in increasing the sensitivity of the actuator. However, the asymmetry of the moving part by two focusing coils causes flexible node vibrations in quite low frequency range. This paper shows that the design modification of the moving part for the reconfiguration of mass moment of inertia can reduce the mode vibrations.

• Informatization Policy
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• v.18 no.2
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• pp.85-98
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• 2011

This paper attempts to develop an index of mobile telecommunications service quality through econometric analysis using data of the leading telco in each OECD country. CapEx of the operator was selected as a proxy variable to represent the quality of the service. To eliminate the part which is dependent on the population and size from CapEx, however, CapEx was regressed on population, area, 3G coverage, Herfindahl-Hirschman Index (HHI) of mobile market, EBITDA margin, and market share of the leading operator. Then, the part of CapEx, which was explained by size and population, was subtracted from CapEx, and the remaining part was regarded as the quality index of mobile telecommunications service. Comparisons among quality indexes of each country revealed that the service quality in Korea and Japan is better than that of France, UK and Germany.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.479-483
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• 2006

As high-definition television(HDTV) broadcasting were generalized, there have been many researches and developments about large storage capacity and fast data transfer rate in optical disk drives(ODD). Pickup actuators must have high flexible mode frequencies and gain margins. Flexible modes are caused by the flexibility of moving parts in the actuator and a servo bandwidth is limited by them. As a result, the system becomes unstable for high-speed operations in high density reading and recording. In this paper, we suggest improved modeling method that considers the bonding layer. And, flexible mode frequency of actuator is improved by Design of Experiment of lens holder. Magnet circuit is designed considering the relation with moving part. Through improving yoke design, the magnetic flux is changed and DC tilt is reduced. Consequently, we designed actuator which has high flexible mode frequency and gain margins.

• Korean Journal of Oriental Medicine
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• v.16 no.3
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• pp.149-154
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• 2010

Objective : Ssanghwa-tang has been used as herbal medine, favorite beverage or health beverage. This study was performed to evaluate the acute toxity and safety of fermented Ssanghwa-tang extract in ICR mice. Methods : 0(control group), 1250, 2500 and 5000 mg/kg of Ssanghwa-tang and fermented Ssanghwa-tang extracts were orally administered to 35 male and 35 female ICR mice. After single administration, we observed number of death, clinical signs, changes of body weight for 14 days. After 14 day of administration, all mice were sacrificed and major organ were observed. Results : Compared with the control group, we could not find any toxic alteration in all treated groups (1250, 2500 and 5000 mg/kg). Conclusions : These results suggest that Sssanghwa-tang fermented with nuruk extracts might be safe to ICR mice.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.22-27
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• 2004

The gas discharge AND gate which have been newly proposed is applied to three electrode surface discharge AC PDP. The address discharge characteristics by the DC-AC floating discharge by which Y electrode is made floating electrode is analyzed The address discharge can be begun by using the floating discharge from the experiment result Moreover, the display discharge can be sustained. The DC priming discharge that the floating discharge is matched to timing is generated in a supplementary electrode. As a result, space charge is supplied enough to the space of the floating discharge and the data voltage is lowered up to l00(V). Driving method to use this DC-AC floating discharge is able to obtain the address operation margin of l00(V).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.42-47
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• 2004

This research has improved the problem of discharge AND gate PDP proposed before. The polarity of the DC discharge which composes AND gate is reversely designed and the cross talk problem to the adjacent scanning electrode has been improved. The AND gate proposed before operated by using non-linearity of the discharge by the space charge. In this research, new discharge NOT logic in which it was used that an applied voltage changed with the discharge circuit was added to AND gate. AND gate came to operate more stably. A selective address was able to be discharged with four horizontal scanning electrodes from the experiment result. The operation margin of the AND gate discharge obtained 34V and of the address discharge obtained 70V.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1429_1430
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• 2009

본 연구에서는 7인치 샘플패널의 가속 Aging 실험을 통해 Aging time(24hr~529hr)변화에 따른 오방전 발생 Mechanism을 분석하고자 했다. 상온에서 Aging time변화에 따른 정마진, 휘도, Vt close curve를 측정 하였고 시간과 온도(고온: $70^{\circ}C$, 상온: $25^{\circ}C$, 저온: $-20^{\circ}C$)에 따른 Discharge time lag의 변화양상을 측정하였다. 그리고 Sustain pulse수의 조절을 통해 패널의 Priming 조건을 제어하면서 오방전 발생 확률을 수치적으로 측정하였다. 실험을 통해, 패널의 Aging time이 늘어남에 따라서 상판의 MgO층에서 Sputtering현상이 발생하여 MgO 잔재들이 하판의 형광체 표면을 덮는 등 방전 개시 전압의 변화가 오방전 발생에 주요한 원인임을 알 수 있었다.

• The Journal of Internal Korean Medicine
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• v.32 no.3
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• pp.334-344
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• 2011

Objectives : Sipjeondaebo-tang is a medicine traditionally prescribed as a restorative. The aim of this study was to investigate the single oral dose toxicity and safety of extract of fermented Sipjeondaebo-tang in ICR mice. Methods : In single oral dose toxicity study, non-fermented or fermented Sipjeondaebo-tang were administered by oral gavage to ICR mice (5 males, 5 females) at single doses of varying concentrations: 1250, 2500 and 5000 mg/kg. Changes of body weight, general behavior, adverse effects and mortality were determined throughout the experimental period. Hematological parameters, organ weights and necropsy findings were evaluated at the end of the experiment. Results : There were no mortality or signs of toxicity in single oral dose toxicity studies. There were also no significant differences in body weight, organ weight, or hematological parameters between the treatment and control groups. Conclusions : Fermented Sipjeondaebo-tang did not cause remarkable adverse effects in ICR mice. The oral lethal dose of fermented Sipjeondaebo-tang is more than 5000 mg/kg and no-observed-adverse-effect level (NOAEL) of the extract for both male and female mice is 5000 mg/kg.

• The Journal of Internal Korean Medicine
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• v.30 no.4
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• pp.780-787
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• 2009

Purpose : This study was carried out to investigate the acute toxicity and safety of fermented Ssanghwa-tang extract. Methods : To evaluate their acute toxicity and safety, 0(control group), 1250, 2500 and 5000 mg/kg of Ssanghwa-tang and fermented Ssanghwa-tang extracts were orally administered to 20 male and 20 female ICR mice. After a single administration, we observed survival rates. general toxicity. changes of body weight, and autopsy. Results : Compared with the control group, we could not find any toxic alteration in any of the treated groups (1250, 2500 and 5000 mg/kg). Conclusions : $LD_{50}$ of Ssanghwa-tang and fermented Ssanghwa-tang extracts might be over 5000 mg/kg and it is very safe for ICR mice.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.437-437
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• 2013

3족 질화물은 우수한 광학 특성과 특히 3족 물질의 조성비 조절로 넓은 대역의 밴드갭 엔지니어링으로 발광다이오드의 물질로 각광 받고 있다. 이와 더불어 발광다이오드의 광추출효율을 향상시키기 위해 다양한 연구들이 활발히 이루어지고 있다. 그 연구 중 하나로 나노, 마이크로 사이즈의 막대와 같은 일차원적 구조와 최근 ITO를 활용한 투명 전극을 대체하여 전도도가 100배 정도 높은 금속을 이용한 옆면 접촉 전극을 도입한 것이 최근 발표되었다. 그러나 옆면 접촉 전극을 형성하기 위해서는 기존의 약 100 nm 정도의 두께의 p-형질화갈륨층은 공정 마진 등에 어려움이 있다. 따라서 기존에 비해 두꺼운 p-형 질화갈륨층이 필요하다. 보통 상용화된 유기 금속화학 증착법을 이용한 p-형 질화갈륨층은 도핑 물질인 Mg의 낮은 활성화와 성장 분위기 중 수소로 인해 양질의 것을 얻기 어렵고 이를 위해 성장 후 추가적인 활성화가 필요하다. 따라서 두꺼워진 p-형 질화갈륨층에 대해서도 기존의 성장 조건과 활성화 조건의 적합 여부와 이에 대한 연구가 필요하다. 따라서 본 연구에서는 양질의 p-형 질화갈륨을 얻기 위하여 성장 조건 및 성장 후 급속 열처리 온도, 시간에 대한 최적화와 약 630 nm 두께의 p-형 갈륨질화층을 가지는 발광다이오드에 대해 급속 열처리 조건에 대한 특성 연구를 실시한다.