• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.338-338
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• 2010

지난 20여년 동안 반도체 레이저 다이오드는 주로 CD (DVD) 픽업용 (파장: 640 nm 이하) 및 통신용 (파장 1550 nm) 광원 분야에서 집중적으로 개발되어 왔다. 그러나 기술의 개발과 더불어 파장조절이 비교적 자유로워지고 광출력이 증대 되면서 기존의 레이저 고유의 영역까지 그 응용분야기 확대되고 있고, 이에 따라 고출력 반도체 레이저 다이오드의 시장 규모도 꾸준히 증가되고 있는 상황이다. 고출력 반도체 레이저 다이오드는 발진 파장 및 광출력에 따라 다양한 분야에 응용되고 있으며, 특히 발진파장이 808 nm 인 고출력 레이저 다이오드의 경우 재료가공, 펌핑용 광원 (DPSSL, 광섬유 레이저), 의료, 피부미용 (점 제거), 레이저 다이오드 디스플레이 등 가장 다양한 응용분야를 가진 광원 중의 하나라고 할 수 있다. MBE(Molecular Beam Epitaxy)로 성장된 InAlAs 에피층 (epi-layer)을 사용하여 고출력을 갚는 레이저 다이오드를 제작함에 있어서, 에피층은 결함 (defect)이 없는 우수한 단결정이 요구되지만, 실제 결정 성장 과정에서는 성장온도와 Al 조성비 등의 성장 조건의 변화에 따라 전기적 광학적 특성 및 신뢰성에 큰 영향을 받는 것으로 보고되고 있다. 이에 본 연구에서는 DLTS (Deep Level Transient Spectroscopy) 방법을 이용하여 InAlAs 양자점 에피층의 깊은 준위 거동을 조사하였다. DLTS 측정 결과, 0.3eV 부근의 point defect과 0.57 ~ 0.70 eV 영역의 trap이 조사되었으며, 이는 갈륨 (Ga) vacancy와 산소 원자의 복합체에 기인한 결함으로 분석된다.

• Composites Research
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• v.32 no.6
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• pp.342-348
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• 2019

Development of flame retarding polymer based materials has been studied actively due to the increase in use of polymers. The post treatment of manufactured fibers or the introduction of flame retardant into fibers is representative method for the way to improve the flame retardancy. Among the polymers, polyacrylonitrile (PAN), which is a precursor of carbon fiber, has been widely used for clothes. Due to low flame retardancy of PAN fiber (LOI value: 17~18%), the improvement of flame retardancy of PAN fiber is needed. In this review paper, we report preparation methods for the fabrication of post-treated (oxidization or chemical reaction) flame-retarding PAN fibers and composites composed of PAN and organic/inorganic materials (SiO₂, 2D materials or CNT).

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.70-77
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• 2011

A ventilation-relief valve performs as a safety-valve assembly for the liquid-propellant feeding system of space launch vehicle. This valve plays a role of relieving the vaporized propellants from propellant tanks during the filling and storing stages of propellants. Also it regulates to maintain the pressure of ullage volume of on-board propellant tanks within the safety-margin during the flight. The simulation model of ventilation-relief valve is designed with AMESim to predict and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of the opening and closing pressures and their operating durations of valve by AMESim analysis are compared with the results of mathematical methods. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditionss, which shall be used in Korea Space Launch Vehicle-II.

• Korean Journal of Plant Tissue Culture
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• v.22 no.2
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• pp.71-76
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• 1995

The effects of light on the activities of several antioxidative enzymes, catalase (CAT), superoxide dismutase(SOD), ascorbate oxidase(AO), and peroxidase(POD) were examined in the hairy root cultures of Phytolacca esculenta van Houtte induced by Agrobacterium tumefaciens $A_4$T. Activities of CAT, SOD, and AO were significantly decreased with incresing light intensity (500-2,000 lx). The activity of AO under high light condition (2,000 lx)was decreased by 92% compared to the dark condition. The activities of glutathoine peroxidase (GPO), ascorbate peroxidase (APO) and general POD were increased under lower light intensify below 500 lx. The activity of GPO under 2,000 lx was decreased by 85% compared to the dark condition. The activities of antioxidative enzymes were more decreased in blue light (400-500nm). The activities of antioxidative enzymes in blue light intensity were increased in lower light intensity below 30 lx, but decreased 21-70% under 200 lx. The activity of AO was decreased by 70% under 200 lx with increasing blue light intensity. Our results suggest that the activities of antioxidative enzymes in hairy roots might be inhibited by endogenous oxidants generated under the high blue light conditions.

• The Journal of Korean Society for School & Community Health Education
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• v.21 no.3
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• pp.21-34
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• 2020

배경 및 목적: 본 연구는 학교 내 응급상황(천식 위기, 알레르기 반응, 저혈당 위기, 발작, 심폐정지, 출혈/골절, 머리/목 상해, 열성질환, 중독, 질식)에 대한 행정 차원과 물품구비 차원에서의 준비 실태, 그리고 응급처치 수행자신감을 파악하는데 목적이 있다. 방법: 단면조사연구로 274명의 보건교사를 대상으로 하였으며, 자가보고형 조사지를 이용하여 대상자와 학교의 일반적 특성, 학교 내 응급상황에 대한 행정·물품 준비 실태, 그리고, 응급처치 수행자신감 등 3개 영역의 자료를 수집하였다. 자료수집은 2018년 2월 1일부터 2018년 7월 31일까지 실시하였고, 자료분석은 기술통계, t-검정과 분산분석을 이용하였다. 결과: 대부분의 학교에서 응급상황 관리계획이 있었으나, 응급상황별로 천식 위기는 46.7%, 알레르기 반응은 58.4%에서만 관리계획을 갖추고 있었다. 산소, 혈당측정기, 자동제세동기, 경추고정장치 등은 85% 이상의 학교에서 보유하고 있었으나, 기관확장제 흡입기, 에피네프린 주사제, 흡인기 등은 거의 갖추고 있지 않았다. 응급상황 수행자신감은 5점 만점에 2.67점 (발작관리) 에서 3.55점 (심폐정지관리)이었으며, 일부 응급상황에 대해서 의료기관 근무경력이 증가함에 따라 수행자신감이 증가하였다. 결론: 대부분의 학교에서 응급관리계획을 수립하고 있었으나, 응급상황별 관리계획을 수립한 경우는 반 정도에 불과하였다. 보건교사의 학교 내 응급상황에 대한 응급처치 수행자신감은 전체적으로 낮게 나타남에 따라, 이들의 역량강화를 위한 체계적인 교육과 멘토링 프로그램이 요구된다.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.103-109
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• 2017

In order to apply the patient monitoring system to the hospital field, it is necessary to be able to measure and analysis data the major bio-signals that are basically covered by the existing patient monitoring system. We have implemented a wearable device and the patient monitoring system for measuring ECG and oxygen saturation. The implemented system transmits the measured bio-signal to the server on the nursing station via Bluetooth. It is represented by graph waveforms and numerical values that can be checked by the medical staff in the patient monitoring system. The validity of this system is verified by comparing the data collected through the designed system with the data obtained from the conventional equipment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.67-71
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• 2007

Recently, a health care need according to the increase of an advanced age population is increasing. The requirement about a health care monitoring is increasing rapidly from general people as well as patient. The requisition about a medical treatment technique and a medical treatment information service is the trend to be expanding. That can be possible minimizing the inconvenience of the patient to take a medical service and continuously monitoring the status of the patient to take a health care service. This paper discusses an implementation of wireless physiological signal monitoring system for health care. The system are composed of the sensor node and monitoring program. The sensor node has the physiological signal measurement part and the wireless communication part. The remote monitoring system has a monitoring program that are communicating the sensor node using bluetooth. The sensor node measured the ECG, pulse wave, blood pressure, Sp02, and heart rate.

• Journal of Korea Water Resources Association
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• v.33 no.1
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• pp.3-14
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• 2000

The primary objective of this study is to estimate the suitable flow in need for conservation and restoration of the fish habitat in running water ecosystem, which has very important status in the instream flow for stream environment. Year, monthly low flows are estimated to properly maintain the fish habitat. Water depth and velocity are simulated, and also water temperature and Dissolved Oxygen(DO) are predicted at gradually varied flow using estimated low flows. These simulated conditions for each low flow are graphically compared with the requirements to maintain fish habitat at each life stage. These processes were applied to 3 riffle transects located at Dalcheon(Dal stream) in the South Han river. Pirami (Zacco platypus) was selected as a representative fish species in Dalcheon. It was shown that the suitable flow for maintaining the representative fish habitat at each life stage depends on hydraulic conditions rather than water quality conditions, and the flow ranges from the 10-year minimum low flow to consecutive 7-day 2.33-year low flow.w flow.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.3-15
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• 2001

The in situ observations and the seawater analyses were conducted for 3 years from August 1996 to August 1999 in order to elucidate and evaluate seasonal variations of marine water quality and trophic state in Mokpo harbour of Korea. Compared the seasonal seawater qualities of Mokpo harbour with the OECD standards of trophic classification in parameters such as Secchi depth, dissolved inorganic nitrogen, phosphate phosphorus and chlorophyll-a, the trophic level of seawater in Mokpo harbour was evaluated to be in mesotrophic or eutrophic state through all 4 seasons and to be in eutrophic state, particularly In summer. The estimation of pollution index by eutrophication showed the seawater quality of Mokpo harbour to deteriorate and fall under the regular grades through all 4 seasons, although the seawater quality of Mokpo harbour was evaluated to be equivalent to the second or third class of the Korean seawater quality standards in view of COD values. The results of eutrophication index estimation showed the high potentiality of red tide occurrence In Mokpo harbour, particularly in summer or fall. In the light of the average atomic ratio of N/P in seawater, the limiting nutrient factor against the growth of phytoplankton was concluded to be phosphorus rather than nitrogen in Mokpo Harbour.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.11-17
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• 1996

Photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were isolated from nature, and were studied for swine wastewater treatment. Growth of those photosynthetic bacteria were increased to 2~3 fold in organic-acid added medium(sodium acetate 1g, sodium propionate 1g and sodium butyrate 1g in Lascelles basal medium $1{\ell}$) than cultivation in Lascelles basal medium, and amount of bacteriochlorophyll a were increased to 1.5~2 fold. Chemical Oxygen Demand(COD) in swine wastewater using photosynthetic bacteria, strains KN 1-1, KN 2-1 and KN 2-3 were reduced 80%, 89% and 75%, respectively.