• 설비공학논문집
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• 제12권3호
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• pp.277-283
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• 2000

The heat transfer characteristics for air jet vertically impinging on a flat plate which had a set of hybrid rod were investigated experimentally. The rod had a cross section made with a half of circular cross section and that of rectangular and was installed in front of the plate. The heating surface was given constant heat flux value of 1020 W/$m^2^{\circ]C$ and the problem parameters investigated were jet Reynolds number, nozzle-to-plate spacing and the rod size. The local and local average Nusselt number characteristics were found to be dependent on the rod size because the flow was disturbed by installing the rod. Higher convective heat transfer rate occurred in the whole plate as well as in the stagnation region.

• Journal of information and communication convergence engineering
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• 제19권1호
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• pp.48-53
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• 2021

Herein, we propose a document analysis system that analyzes papers or reports transformed into XML(Extensible Markup Language) format. It reads the document specified by the user, extracts keywords from the document, and compares the frequency of keywords to extract the top-three keywords. It maintains the order of the paragraphs containing the keywords and removes duplicated paragraphs. The frequency of the top-three keywords in the extracted paragraphs is re-verified, and the paragraphs are partitioned into 10 sections. Subsequently, the importance of the relevant areas is calculated and compared. By notifying the user of areas with the highest frequency and areas with higher importance than the average frequency, the user can read only the main content without reading all the contents. In addition, the number of paragraphs extracted through the deep learning model and the number of paragraphs in a section of high importance are predicted.

• 한국철도학회논문집
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• 제15권6호
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• pp.631-637
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• 2012

수서-평택간 수도권과 호남고속철도 1단계사업이 2014년 말 개통됨에 따라 고속철도의 제2의 도약을 맞이하게 되었다. 하지만, 수도권 고속철도 건설기본계획에 준해 고속열차가 설정될 경우 수도권 고속열차와 기존 고속열차의 합류지점인 평택-오송 구간에서 고속선 선로용량의 최대치에 도달하게 되는데, 이로인해 천안아산역의 정차열차 수를 제한을 받게 되며 장기적으로 열차수요가 늘어나면 고속열차를 추가설정 할 수 없는 제약요인으로 작용이 예상된다. 본 연구는 고속선의 신호체계인 TVM430시스템의 열차설정 이론을 기초로 운행시 격 및 열차횟수를 산정방법을 검토한 후, 첨두시간대 병목구간인 평택-오송간의 최적의 열차운행패턴 적용방안을 제시하였다. 또한 적용방안을 운영에 도입할 경우 기대되는 효과와 문제점을 대안별로 분석하여 현 여건에 맞는 단계적 정책대안을 제시하였다. 분석결과 현재의 고속열차 운영시스템에 최소운행시격을 설정하여 병목구간을 운행한다면 추가투자비용 없이 선로용량초과 문제를 해결할 수 있을 것으로 사료된다. 향후 중장기 열차운영계획 등에 대안들이 반영된다면 고속선 병목구간(MLP, Maxmum Load Point)해소 등 열차운영효율 향상에 기여 할 것으로 기대된다.

• 농약과학회지
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• 제14권2호
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• pp.133-137
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• 2010

콩탄저병의 수량에 미치는 영향을 조사하고, 요방제 수준을 설정하기 위하여 2년간 포장에서 시험하였다. 탄저병의 발병협율과 수량, 완전립수, 불완전립수, 협수와는 상관계수가 각각 -0.85, -0.78, 0.80, -0.64로 5% 수준에서 유의성이 있는 협수를 제외하고는 모두 1% 수준에서 고도의 상관이 있었다. 탄저병 발병협율(X)을 독립변수로 콩수량(Y)을 예측했을 때의 단순직선회기 모델은 Y=-1.7781X+164.22로 결정계수($R^2$)는 0.8092였다. 상기 회귀식에서 경제성을 고려하지 않고 수량에 영향을 주기 시작하는 요방제 수준은 발병협율 6.9%로 산출되었으며, 방제비용을 보상할 수 있는 경제적 피해수준 및 경제적 방제수준은 각각 발병협율 11.9%와 9.5% 로 산정되었다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권1호
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• pp.32-40
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• 2016

Purpose: The purpose of this study is to analyze the effect of sampling points on accuracy of storage reliability estimation for one-shot systems by assuming a weibull distribution as a storage reliability distribution. Also propose method for determining of sampling points for increase the accuracy of reliability estimation. Methods: Weibull distribution was divided into three sections for confirming the possible to estimate the parameters of the weibull distribution only some section's sample. Generate quantal response data for failure data. And performed parameter estimation with quantal response data. Results: If reduce sample point interval of 1 section, increase the accuracy of reliability estimation although sampling only section 1. Even reduce total number of sampling point, reducing sampling time interval of the 1 zone improve the accuracy of reliability estimation. Conclusion: Method to increase the accuracy of reliability estimation is increasing number of sampling and the sampling points. But apply this method to One-shot system is difficult because test cost of one-shot system is expensive. So propose method of accuracy of storage reliability estimation of one-shot system by adjustment of the sampling point. And by dividing the section it could reduce the total sampling point.

• 한국전산구조공학회논문집
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• 제35권2호
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• pp.65-71
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• 2022

최근에는 경량화 문제에 대한 합리적인 솔루션을 제공하고 유용한 개념설계를 제공할 수 있는 다중 재료 구조 위상최적화가 더욱 중요해지고 있다. 기존의 MMTO(Multi-Material Topology Optimization)의 경우 후보 물질의 수가 증가할수록 설계변수의 수도 증가하고, 결과적으로 계산 시간이 크게 증가한다. 따라서 PSM(Phase Section Method)과 같은 단일 설계변수를 갖는 MMTO가 제안되었다. 본 연구는 조성비가 면적이나 부피비를 나타내지 못하고, 설계변수가 목표치에 충분히 집중되지 않고, 특정 재료가 요구량보다 적게 생성되는 PSM의 세 가지 주요 제한점을 고려하여 이를 개선하는데 중점을 둔다. 이러한 한계를 극복하기 위해 재정의된 조성비와 더 나은 수렴을 위한 조정된 매개변수를 제안한다. 제안된 수정 사항의 유효성을 2차원 및 3차원 수치 예제를 통해 검증한다.

• 한국자원식물학회지
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• 제16권1호
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• pp.49-54
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• 2003

옻나무의 근삽에 의한 묘목생산에 있어서 적정삽목 시기와 삽수의 절단 여부에 따른 신초발생율과 묘소질을 조사하였다. 삽목시기가 빠를수록 신초는 3-4주 후부터 발생하여 늦은 경향이었으나 삽식 10주 후의 신초 형성율은 높은 경 향이었는데 3월 15일과 25일 및 4월 5일 삽목구는 84% 이상이었으며, 신초는 삽목시기가 늦을수록 각시기별로 고르게 발생하는 경향이었다. 묘소질은 4월 5일과 3월 25일 삽목구가 수장, 주당 분지수, 엽수, 경직경 및 엽면적 모두 가장 양호하였다. 절단하지 않은 삽수로부터 신초의 발생은 2주 후부터 시작되었으나 절단한 삽수로부터는 3주 후부터 시작되어 약 1주일이 늦었다. 그러나 삽식 6주 이후부터 10 cm의 크기로 절단한 삽수의 신초발생율은 급격히 증가하여 10주 후에는 84%이었으나 절단하지 않은 삽수의 신초발생율은 54%로 매우 낮았다. 절단하지 않은 삽수의 묘가 경시적으로는 양호하였으나, 수장, 분지수 및 경직경 등은 통계적인 유의성이 인정되지 않았다.

• 수산해양교육연구
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• 제6권1호
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• pp.58-76
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• 1994

Heat transfer and pressure drop measurements are made on low integral-fin tubes in turbulent water flow condition. The integral-fin tubes investigated in this paper are nominally 19mm in diameter. Eight tubes have been used with trapezoidally shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. Plain tube having same diameter as finned tube is also tested for comparison. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of $30^{\circ}C$ on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken on steady state. The heat transfer loop is used for testing single long tubes and cooling water is pumped from a storage tank through filters and flowmeters to the horizontal test section where it is heated by steam condensing on the outside of the tube. The pressure drop across the test section is measured by means of pressure gauge and manometer. Each tube tested is cleaned with sodium dichromate pickling solution and well rinsed with water prior to installation in the test section. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, heat transfer of finned tube is enhanced up to 4 times as that of a plain tube at constant Reynolds number and up to 2 times at constant pumping power. 2. Friction factors are up to 1.6~2.1 times those of plain tube. 3. At a given Reynolds number, Nusselt number decrease with increasing pitch to diameter. 4. The constant pumping power ratio for low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio.

• Journal of the Korean Wood Science and Technology
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• 제16권1호
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• pp.9-20
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• 1988

Lespedeza species have been widely used not only as plant resources for bark, leaves and honey, but also as erosion control materials. This study was carried out to investigate the structural and wood tiber characteristics in order to obtain basic information for the utilization of the wood. The wood structure was investigated for 10 selected species and the wood fiber, for the 5 selected species among Lespedeza species distributed all over the country. The following results were obtained. In the cross section, campylotropis showed ray diffuse porous wood, L. bicolor, L. cyrtobotrya, L. thunbergii var. intermedia, diffuse porous wood, and L. tomentella, L. angustifolioides. L. maritima, L. robusta, L. patentibicolor, ring porous wood. The maximum diameter of a single vessel ranged 66-123 ${\mu}$ in all species. Campylotropis showed the most number of vessels, L. angustifolioides, the least. The number of ray per mm ranged 7-22, Campylotropis showed the most number of rays, L. angustifolioides, the least. In the radial section the average length of vessel ranged 121-250 ${\mu}$ in all species. L. thunbergii var. intermedia showed the longest vessel, L. tomentella, the shortest. In tangential section the average width of the uniseriate ray ranged 9.2-14.7${\mu}$, that of the multiseriate ray, 19.2-42.1 ${\mu}$. The average height of the uniseriate ray ranged 143.0-1162.0 ${\mu}$. The width of fiber ranged 10.12-13.61 ${\mu}$, L. maximowiezii showed the narrowest tiber, L. thunbergii var. intermedia. the widest, the thickness of fiber wall ranged 2.93-3.71 ${\mu}$ in the five species. L. maximowiezii showed the most thin fiber wall, L. thunbergii var. intermedia, the thickest, L. cyrtobotrya showed the difference in the size of fiber between the shade and the sunny sites but L. maximowiezii showed no difference. There was significant difference in fiber length, fiber width and wall thickness between L. eyrtobotrya and L. maximowiezii.

• 수산해양기술연구
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• 제30권2호
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• pp.78-85
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• 1994

The author carried out an experiment to find out the response of Striped puffer. Fugu xanthoperus (Temminck et Schlegel) to the color lights. The experimental tank (300L$\times$50W$\times$50Hcm) was set up in a dark room. Six longitudinal sections with 60cm intervals are marked in the tank to observe the location of the fish. Water depth in the tank was kept 50cm level. Light bulbs of 20W at the both ends of the tank projected the light horizontally into the tank. Two different colored filters were selected from four colors of red, blue, yellow, and white, and the were placed in front of the light bulbs to make different colors of light. Light intensity was controlled by use of auxiliary filiters intercepted between the bulb and the filter. The fishes were acclimatized in the dark for 60 minutes before they were employed in the experiment. Upon turning on the light, the number of fish in each section was counted 40 times in 30 second intervals, and the mean of the number of fish in each section was counted 40 times in 30 second intervals, and the mean of the number of fish in each section was given as the gathering rate of the fish. The colors favourited by the fish was found in order of blue, yellow, white and red in the daytime, and blue, white, yellow and red at night. The difference of the average distribution on two different colors of light was 13.12%(4.10-26.55%), and the difference in the daytime(14.79%) was larger than at night (11.45%). Constantly the gathering rate of fish on illumination period was fluctuated with instability. As the gathering rate of fish on illumination period was fluctuated with instability. As the gathering rate on one color of light increased, the gathering rate on the other color of light decreased. The difference of the gathering rate on two different colors of light was comparatively distinct and the difference in the daytime was larger than at night.