• 한국산림과학회지
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• 제97권6호
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• pp.680-689
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• 2008

본 연구에서는 층층나무, 물푸레나무, 박달나무, 개벚나무, 고로쇠나무를 대상으로 차광처리를 통해 4가지 수준(상대 차광률; 전광처리구, 전광대비 65~72%, 29~40%, 7~12%)으로 광도 조건을 달리하여 광합성 특성을 조사하였다. 그 결과, 층층나무, 물푸레나무 및 박달나무는 차광처리에 의하여 광합성 능력과 엽록소 형광이 저하하여, 내음성 수준이 낮음을 시사하였다. 개벚나무는 조사 시기별 차이는 있었으나, 강피음 처리구를 제외한 나머지 세 처리구에서 좋은 광합성 능력을 나타내, 보통 수준의 내음성을 보였다. 한편 고로쇠나무는 전광대비 29~40% 처리구에서 가장 높은 광합성 능력과 엽록소 형광을 나타내, 내음성 수준이 공시수종 중에 가장 높음을 시사하였다.

• KIEAE Journal
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• 제11권6호
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• pp.53-62
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• 2011

This study aimed at suggesting improvement of lighting environment of the coffee house using study place. To this end, a series of field investigation was conducted in four possible target coffee houses around university. The field measurement included measurement of general illuminance and tabletop illuminance, observing illumination condition, and status of artificial lighting. Also, on-site questionnaire survey was administrated to 80 users of field measurement targets about using characteristics of coffee house and user's subjective response on light environment. The results are summarized as follows: (1) According to questionnaire survey, most of users checked 'learning (study and reading)' in 'purpose of coffee house using', and 'slightly dark' was checked most in each subjective response (brightness on general space and on tabletop at daytime/night); (2) as results of measurements on general illuminance and on tabletop illuminance during daytime, only one coffee house was suitable for standard; (3) as results of measurements on illuminance during night, all target coffee houses were not met the standard; (4) as results of uniformity ratios, almost uniformities of general illuminance were not met the standard except one case. The common problems of lighting environment of coffee house were analyzed as lack of daylight illumination e.g. having low amount of sunshine from skylight, un-uniformity of insolation by floor plan and absence of window blind, and un-uniformity of artificial luminous intensity e.g. lack of the number or brightness of artificial lighting, using the indirect lighting, using only local lighting, and non-uniform arrangement of artificial lighting.

• 전력전자학회논문지
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• 제15권1호
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• pp.35-42
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• 2010

본 논문은 고효율의 조명용 LED 구동회로를 위해 LLC 공진형 컨버터를 이용한 2단 구성의 LED 구동회로를 제안한다. 기존의 3단 구성의 LED 구동회로는 LED의 휘도 및 제어를 위해 별도의 비절연형 DC/DC 컨버터를 사용하여 낮은 효율의 문제점을 지니고 있었다. 이러한 문제를 해결하기 위해 제안된 회로는 비절연형 DC/DC 컨버터 단 없이 PFC단과 LLC단으로 총 2개의 단으로 구성하였다. LLC단에서 절연과 LED의 제어 및 휘도 조절 기능이 가능하여 90% 이상의 고효율 동작을 보장한다. 본 논문에서는 제안회로의 동작원리를 설명하고, 모의실험 및 45W급 LED 구동회로를 제작하여 하드웨어실험을 통해 제안회로의 유용성을 검증하였다.

• 한국식물병리학회지
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• 제13권4호
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• pp.210-214
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• 1997

포도 흰가루병균(Uncinula necutor)의 분생포자 형성, 발아 및 균사 초기생장에 미치는 중요 환경오인과 살균제의 영향을 구명하기 위하여 수행한 연구 결과를 요약하면 다음과같다. 분생포자 형성은 상대습도 76~96%에서 가장 좋았다. 포자 발아 및 균사 초기생장은 증류수에 비해 5% 한천배지에서 좋았으며, 온도 $26^{\circ}C$, pH 5.0일 때 가장 좋았다. 광 100 lux는 암상태와 발아율에 차이가 없었으며 한천배지에 포도 엽즙액 30%를 첨가한 배지에서는 순수 한천배지 보다 좋았다. 또 triazole계 살균제 첨가 배지에서의 포자발아 및 균사생장은 살균제 농도증가에 비례하여 급격히 감소하였으나 그 정도는 살균제의 종류에 따라 차이가 있었다. 특히, myclobutanil은 농도증가에 따른 발아율의 감소정도가 매우 낮았다.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.80-85
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• 2017

최근 고부가가치 산물의 생산이 가능한 미세조류는 이산화탄소의 생물학적 전환 측면에서 많은 주목을 받고 있다. 그렇지만 미세조류 종 자체가 지닌 낮은 광합성 효율 및 생산성의 한계는 미세조류를 활용한 공정의 상업화를 막는 장애요인이다. 따라서 본 연구에서는 대표 미세조류 Chlamydomonas reinhardtii의 광독립영양 성장성 분석을 위한 미세액적 광생물반응기를 개발하였다. PDMS 기반의 미세유체 칩 내에 미세기둥을 배열하고 미세챔버의 높이를 조절하여 미세액적 내 이산화탄소의 전달속도를 증가시켰으며, 이는 세포 성장성과 형광 세기 변화를 통해 확인하였다. 마지막으로 미세액적 광생물반응기를 활용하여 다양한 이산화탄소 농도 및 광량 조건에서 C. reinhardtii의 광독립영양배양에서 성장성을 96 시간동안 관찰하고 분석하였다. 본 연구 결과를 통해 미세액적 광생물반응기는 성장성 및 유용물질 생산성이 우수한 미세조류 종을 빠르게 분석하고 쉽게 분리할 수 있는 효율적인 플랫폼임을 입증하였다.

• 한국전문물리치료학회지
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• 제12권1호
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• pp.80-90
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• 2005

The purpose of this study was to evaluate the effects of pulsed ultrasound on wound healing and observe during the wound healing process the distribution of mast cells according to histopathologic findings. Eighty Sprague Dawley rats which were divided into 4 groups received full thickness skin wounds on the back. Each of the 5 animals was sacrificed immediately and then sacrificed again 1, 3, 6, and 12 days after injury. Specimens from the wounds were removed during healing and routinely processed with a hematoxylin-eosin stain and a toluidine blue stain. The authors then observed the distribution of mast cells under a light microscope. The results of this study were as follows: The rate of wound healing and the length of the wounds of the pulsed ultrasound group II was significantly faster than group I on day 6 and day 12 (p<.001). Group III showed the most significant effect after12 days (p<.001). Group IV also showed a significant effect at 12 days (p<.01). A low-intensity ultrasound .5 $W/cm^2$ resulted in a fast healing rate. During the wound healing process mast cells had a tendency to decrease in the acute inflammatory phase. During the wound healing process mast cells were thought to contribute to the healing of the wound.

• 한국재료학회지
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• 제23권3호
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• pp.161-167
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• 2013

The ZnO thin films were grown on GaN template substrates by RF magnetron sputtering at different RF powers and n-ZnO/p-GaN heterojunction LEDs were fabricated to investigate the effect of the RF power on the characteristics of the n-ZnO/p-GaN LEDs. For the growth of the ZnO thin films, the substrate temperature was kept constant at $200^{\circ}C$ and the RF power was varied within the range of 200 to 500W at different growth times to deposit films of 100 nm thick. The electrical, optical and structural properties of ZnO thin films were investigated by ellipsometry, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and by assessing the Hall effect. The characteristics of the n-ZnO/p-GaN LEDs were evaluated by current-voltage (I-V) and electroluminescence (EL) measurements. ZnO thin films were grown with a preferred c-axis orientation along the (0002) plane. The XRD peaks shifted to low angles and the surface roughness became non-uniform with an increase in the RF power. Also, the PL emission peak was red-shifted. The carrier density and the mobility decreased with the RF power. For the n-ZnO/p-GaN LED, the forward current at 20 V decreased and the threshold voltage increased with the RF power. The EL emission peak was observed at approximately 435 nm and the luminescence intensity decreased. Consequently, the crystallinity of the ZnO thin films grown with RF sputtering powers were improved. However, excess Zn affected the structural, electrical and optical properties of the ZnO thin films when the optimal RF power was exceeded. This excess RF power will degrade the characteristics of light emitting devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.144-144
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• 2008

Blue light emitting diode structures consisting of the InGaN/GaN multiple quantum wells were grown by metalorganic chemical vapor deposition at different growth temperatures for the p-GaN contact layers and the influence of growth temperature on the emission and microstructural properties was investigated. The I-V and electroluminescence measurements showed that the sample with a p-GaN layer grown at $1084^{\circ}C$ had a lower electrical turn-on voltage and series resistance, andenhanced output power despite the low photoluminescence intensity. Transmission electron microscopy (TEM) revealed that the intense electro luminescence was due to the formation of a p-GaN layer with an even distribution of Mg dopants, which was confirmed by TEM image contrast and strain evaluations. These results suggest that the growth temperature should be optimized carefully to ensurethe homogeneous distribution of Mg as well as the total Mg contents in the growth of the p-type layer.

• 대한전자공학회논문지SD
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• 제44권7호통권361호
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• pp.24-30
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• 2007

본 연구에서는 광 논리 및 광 스위칭 시스템에 응용할 수 있는 수직 구조 레이저 - 완전 공핍 광 싸이리스터 (vertical cavity laser - depleted optical thyristor, VCL-DOT)를 제작하고, 본 연구실에서 제안한 차동 스위칭 방법을 이용하여 광 로직(AND, OR, NAND, NOR, INVERT) 함수를 구현하였고, 그 특성을 측정, 분석하였다. 제작한 VCL-DOT는 0.65 mA의 낮은 레이징 문턱 전류, 0.38 mW/mA의 높은 slope efficiency, 그리고 낮은 입력 광 파워에도 높은 민감도를 보인다. 차동 소자타입의 광 싸이리스터를 이용하면 복잡한 전기 회로를 이용하지 않고도, 집적화된 단일 소자에서 간단한 기준 광입력 시호의 파워를 제어함으로써 다양한 광 로직 게이트를 구현할 수 있다는 장점을 갖는다.

• 아시안잔디학회지
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• 제7권1호
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• pp.19-30
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• 1993

Experiments were conducted to investigate propagation, shade tolerance, cold resistance and growth rate of evergreen ground cover plants ; Vinca minor K , Ajuga reptans L., Ophiopogon japonicus ker. f nanus hort , and Hedera helix.. The results were as follows : 1.It is convenient to use the growing case for rice seed to grow and transplant Vinca minor seed-ling. The most proper density of transplanting Vinea was 180 plants per 1m$^2$. At the end of growing season, the coverage came up to 90% The rooting ability of Hedera helix was best to cut from April to May (temperature 15~23˚C). The seedling length of Parthenocissus quinguefohlia were irregular and ranged from 5 cm of 200cm. 2. Ajuga reptans L., Ophiopogon j. and Vinca minor L. grew better under 50% light intensity than full sunlight. Particularly, under full sunlight and aestival high temperature, there were a few withering plants in Ajuga reptans L. , and V Vilica minor L. 3. Of Vinca minor K., Ajuga reptans L. , Ophiopogon japonicus ker. f. nanus hort. and Hedera helix. acclimatized in open field, where temperature was from -7~8˚C. There were few plants had damage in low temperature incubator to -16˚C after field acclimatization. 4.Tendrils of Parthenocissus quinguefolia strongly clung to the wire netting stone fence but intruded into the gap and cranny of the precast concrete fence and so clung to, so that it needed to install the bending net on the precast concrete fence.