• 한국태양에너지학회 논문집
• /
• 제32권5호
• /
• pp.41-51
• /
• 2012

Heliostat field is the most important subsystem in the tower type solar thermal power plant since its optical performance affects the total system efficiency most significantly while the construction cost of it is the major part of total construction cost in such a power plant. Thus a well designed heliostat field to maximize the optical efficiency as well as to minimize the land usage is very important. This work presents methodology, procedures and result of heliostat filed design for 200kW solar thermal power plant built recently in Daegu, Korea. A $2{\times}2(m)$ rectangular shaped receiver located at 43(m) high and tilted $28^{\circ}$ toward heliostat field, 450 of heliostats of which the reflective surface is formed by 4 of $1{\times}1(m)$ flat plate mirror facet, and the land area having about $140{\times}120(m)$ size are used to form the heliostat field. A procedure to deploy 450 heliostats in radial staggered nonblocking formation is developed. Also the procedures to compute the cosine effect, intercept ratio, blocking and shading ratio in the field are developed. Finally the heliostat filed is designed by finding the optimal radial distance and azimuthal spacing in radial staggered nonblocking formation such that the designed heliostat field optical efficiency could be maximized. The designed heliostat field has 77% of annual average optical efficiency, which is obtained by annually averaging the optical efficiencies computed between the time of where sun elevation angle becomes $10^{\circ}$ after sunrise and the time of where sun elevation angle becomes $10^{\circ}$ before sunset in each day.

• 한국자원식물학회지
• /
• 제33권5호
• /
• pp.460-466
• /
• 2020

본 연구 결과들을 바탕으로 도깨비부채 잎(RPL)은 GSK3β활성화를 통해 IκB-α를 인산화시켜 단백질 분해를 유도하고 IκB-α분해로 인해 p65 핵내 전이를 유도하여 NF-κB 신호전달을 활성화시킨다. 이러한 NF-κB 신호전달 활성화를 통해 대장암의 세포생육을 억제하는 것으로 추정된다. 본 결과는 도깨비부채 잎을 소재로 항암을 목적으로 한 천연치료제 및 대체보완소재 개발에 활용할 수 있다고 판단된다. 그러나 도깨비부채 잎의 대장암에 대한 세포생육 억제와 작용기전의 정확한 관련성과 세포생육 억제활성 물질 분석을 위해 추가적인 연구가 필요할 것으로 사료된다.

• Advances in Traditional Medicine
• /
• 제4권3호
• /
• pp.157-161
• /
• 2004

We showed the effects of the traditional herbal medicine, Jukyeoondam-tang (JO-T, Zhu-ru-Wen-Dan-Tang in Chinese), on ventricular arrhythmia induced by aconitine. Electrophysiological experiments with conventional microelectrode techniques revealed that JO-T potently suppressed the aconitine-induced arrhythmias in ventricular strips of the rat. In the aconitine-induced arrhythmia model of the rat, pretreatment with JO-T $(100\;{\mu}g/ml)$ completely occluded the appearance of ventricular tachyarrhythmia (VT) or ventricular fibrillation (VF) induced by aconitine. Furthermore, the aconitine-induced ventricular arrhythmia was occluded by $Na^+$ channel blocker quinidine but was not occluded by $K^+$ channel blocker glibenclamide $(3\;{\mu}mol/L)\;and\;Ca^{2+}$ channel blocker nifedipine $(10\;{\mu}mol/L)$. We also confirmed the effect of JO-T in the ischemia-reperfusion (I/R)-induced arrhythmia model of the rat. JO-T did not affect the I/R-induced arrhythmias in rats. JO-T may alleviate the risk of ventricular arrhythmias following aconitine. These results suggest that JO-T is a potent antiarrhythmic drug having a$Na^+$ channel-blocking action.

• 한국과학교육학회지
• /
• 제25권4호
• /
• pp.465-471
• /
• 2005

이 연구에서는 과학 성취도, 과학 학습 동기, 자아존중감의 측면에서 상호동료교수 전략의 효과를 조사하였다. 남녀 공학 중학교에서 2학년 3학급(94명)을 비교 집단, 협동학습 집단, 상호동료교수 집단으로 배치하였다. '혼합물의 분리' 반원에 대하여 13차시 동안 수업을 실시하였다. 이원 공변량 분석 결과, 과학 성취도 검사에서 상호동료교수 집단의 점수가 비교 집단에 비해 높았음에도 불구하고, 세 집단간에 유의미한 차이는 없었다. 과학 학습 동기의 모든 하위 영역에서는 상호동료교수 집단의 점수가 비교 집단보다 유의미하게 높았다. 특히, 과학 학습 동기의 자신감 영역에서는 상호동료교수 집단의 점수가 다른 두 집단에 비해 유의미하게 높았다. 자아 존중감에서는 상호동료교수 집단 하위 학생들의 점수가 협동학습 집단에 비해 유의미하게 높았다.

• 컴퓨터교육학회논문지
• /
• 제7권5호
• /
• pp.83-91
• /
• 2004

본 논문에서 청소년들의 정신 건강을 해치는 유해 정보 사이트를 차단하기 위해 기존 방식이 아닌 내용 기반을 중심으로 하여 중요도가 가장 높은 한 개의 복합 키워드와 정보통신윤리 위원회에서 제시한 유해단어의 가중치를 이용하여 가중치 평균을 더해 유해도를 판단하여 유해 사이트와 일반 사이트를 구별하는 시스템을 구현하였다. 예비 실험을 통해 구해진 유해도의 값 3.5를 유해정보 사이트를 판단하는 기준으로 정한 다음 유해 정보 차단 시스템의 성능 실험을 위해 유해 정보 사이트와 일반 사이트를 각각 무작위로 100개씩 추출해 접속해 본 결과 유해 사이트를 유해 정보 사이트로 판명한 비율이 78%를 보였고 일반 사이트를 일반 사이트로 판명한 비율이 96%가 되어 본 시스템의 유효성을 확인 할 수가 있었다.

• 한국통신학회논문지
• /
• 제27권6A호
• /
• pp.610-617
• /
• 2002

본 논문에서는 적응적 변이추정 기법을 이용한 새로운 중간시점영상합성 방법을 제시하였다. 즉, 스테레오 입력 영상으로부터 특징값을 추출하고, 설정된 임계값과 비교하여 특징값의 크기를 결정한 다음, 특징값의 크기에 따라 정합창의 크기를 적응적으로 선택하여 정합함으로써 중간시점의 영상을 합성하는 새로운 기법을 제안하였다. 제안된 기법에서는 배경과 같인 특징값이 작은 영역에서는 비교적 큰 정합창에 의한 블록정합이 이루어지고 물체의 윤곽선과 같이 특징값이 큰 영역에서는 상대적으로 작은 정합창에 의한 미세한 정합이 적응적으로 수행되기 때문에 전체적인 정합성능의 개선뿐만 아니라 기존의 기법에서 나타나는 오정합이나 블록화 현상등의 문제점 해결의 가능성을 제시하였다. 또한, 'Parts' 및 'Piano' 영상을 사용한 실험결과 본 논문에서 새로이 제안한 중간시점 영상합성 방법은 기존의 방식에 비해 평균적으로 PSNR은 약 2.32∼4.16dB가 향상되었고, 수행시간은 약 39.34∼65.58% 감소됨을 확인하였다.

• The Korean Journal of Ceramics
• /
• 제5권4호
• /
• pp.379-385
• /
• 1999

Minute boehmite crystals with high aspect rations, which were hydrothermally synthesized from gibbsite in $Ba(OH)_2$ solution, occluded Ba with the Ba/Al molar ratio of about 0.03 in their interlayers. Their surface areas were about 14$\m^2$/g. The Ba-intercalated bohemite samples were partly used for producing $BaAl_{12}O){19}$ with low sinterability by externally supplementing $Ba(OH)_2$, and for forming transient aluminas. The surface area of $BaAl_{12}O){19}$ obtained by firing at $1500^{\circ}C$ for 3 h was 5.3$\m^2$/g, which was significantly lower than 12$\m^2$/g of the sol-gel origin. While a mixture ${\gamma}$-alumina and BaO is known to from $BaAl_{12}O){19}$ at $1200^{\circ}C$, solid state reaction between η-alumina transformed from the Ba-intercalated boehmite and BaO formed from $Ba(OH)_2$ deposited on the boehmite started above $1300^{\circ}C$. This suggests that large sized $Ba^{2+}$ ion occluded in η-alumina considerably suppresses the diffusion of $Al^{3+}$ ion. The surface area of the Ba-intercalated boehmite fired at $1400^{\circ}C$ for 3h was as high as 14$\m^2$/g indicative of its potential applicability to combustion catalysts. But it was decreased to 5.0$\m^2$/g after firing at $1500^{\circ}C$ for 3 h, accompanied by abrupt formations of $\alpha$-alumina and $BaAl_{12}O){19}$ as main products. The suppression of $\alpha$-alumina formation up to $1400^{\circ}C$ also suggests the significant blocking effect of $Ba^{2+}$ ion on the diffusion of the component ions.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.1070-1073
• /
• 2003

We have studied the characteristics of organic light-emitting diodes(OLEDs) with the PTFE buffer layer. The OLEDs have been based on the molecular compounds, N,N'-diphenyl-N,N'-bis (3-methylphenyl)-1, 1'- biphenyl-4, 4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum (III) ($Alq_3$) as an electron transport and the Polytetrafluoroethylene (PTFE) as a buffer layer. The devices of structure were fabricated ITO/PTFE/TPD(40nm)/$Alq_3$(60nm)/Al( 150nm) to see the effects of the PTFE buffer layer in organic EL devices. The thickness of the PTFE layer varied from 0.5 to 10[nm]. We were measured Current-Voltage-Luminance Characteristics and Luminance efficiency due to the variation of PTFE thickness. the PTFE layer was reported that helped to enhance the hole tunneling injection and effectively impede induim diffusion from the ITO electrode. We have obtained an improvement of luminance efficiency when the PTFE thickness is 0.5[nm] is used. The improvement of efficiency of is expected due to a function of hole-blocking of PTFE in OLEDs.

• 전기학회논문지
• /
• 제64권1호
• /
• pp.171-175
• /
• 2015

In this paper, because of global environmental problems such as energy shortage and abnormal climate, green energy development and energy saving technology development is being magnified. Heat insulation, the most basic and traditional energy saving method, is highly expected. Especially, simple and advanced heat insulation technique based on Nano material is promising future technology. The railway system also requires heat insulation. Especially, traditional heat insulator such as glass wool has been adopted frequently to rolling stock. The heat insulator is also adopted in general railway service buildings. Take account of cost-effective heat blocking performance, the heat insulator shall be adopted in diverse fields such as electric power, railroad, signal and communication. The only and direct solution for this problem is installing heat insulator with outstanding endurance, corrosion resistance and heat resistance to block outer heat Upgrading heat specification of equipment can be a solution, but since price and maintenance cost rise severely, this plan might be incongruous. In this research, energy saving effect of ultrathin heat insulator film was demonstrated by installing the film on roof of electrical room.

• 구강회복응용과학지
• /
• 제23권2호
• /
• pp.171-178
• /
• 2007

Botulinum toxin type A (BTX-A) has a local effect at the neuromuscular junction by blocking acetylcholine release and thus causing paralysis and atrophy of the affected muscles. In dentistry, Botulinum toxin type A(BTX-A) is used for the treatment of masseteric hypertrophy, temporomandibular disorder, and severe bruxism related neurologic disorder. We hypothesized that the muscle atrophy after BTX-A injection into masseter muscle in growing rats, could affect the jaw growth. The purpose of this study was to determine the effects of the BTX-A injected into the masseter muscle on the jaw growth in rats. Rats were divided into four groups(group 1; control group, group 2; saline injection group, group 3; BTX-A injection group, group 4; baseline control group). Group 4 was sacrificed at the beginning of the experiment to provide baseline values of jaw measurements. The weight, length and width of jaw in those groups were measured every weeks. This study reported that the mandibular body length, condylar length, coronoid process length, anterior region height, coronoid process height and condylar height of the jaw in BTX-A injection group were shorter than those of the control and saline injection groups(P<0.05). In conclusion, BTX-A injected into the masseter muscle may affect the undergrowth of the jaw in rats.