• 대한기계학회논문집B
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• 제39권8호
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• pp.703-711
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• 2015

작업의 효율을 높이기 위해서 대형 공장에서 개구부는 주로 개방 되어 있다. 그러나 동절기에 공장에서 난방을 하는 경우 개방되어 있는 개구부는 난방부하를 상승시키는 큰 요인이다. 때문에 공장에서는 개구부 상단에 에어커튼을 설치하여 외부의 침기를 막아 난방부하를 낮춘다. 일반적인 에어커튼의 설계 변수로는 토출 각도와, 속도, 온도 등이 존재하며 이에 대한 연구는 이미 많이 진행되었다. 하지만, 공장이라는 공간적 특수성을 고려하였을 때, 기존에 연구되지 않은 개구부로부터의 이격 거리와 토출구 폭에 대한 부분도 차단 성능에 영향을 미친다. 그 결과 에어커튼은 이격 거리가 가깝고, 토출구 폭은 넓을수록 차단 성능이 좋았다. 이격 거리가 존재하더라도 토출구 폭을 증가시키면 차단 성능이 향상되었으며, 토출구 폭을 증가시킴으로써 약 13.7%의 차단 성능의 향상을 기대할 수 있다.

• 정보처리학회논문지B
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• 제12B권5호
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• pp.527-534
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• 2005

영상에 회전이나 크기 변형이 가해지면 영상을 구성하는 점들의 좌표값들이 변경되어 형태 기술 및 인식이 어렵게 된다. 그러나 영상을 구성하는 점들 간의 위치관계나 무게중심과의 위치 관계는 변하지 않는다. 따라서 x-y 좌표계로 기술되는 영상 공간의 점들을 회전 및 크기 변형에 불변하는 새로운 좌표계로 사상할 수 있다면, 형태 기술 및 인식의 문제는 보다 수월해진다. 본 논문에서는 영상 공간의 점들을 회전 및 크기 변형에 무관한 새로운 특징 공간으로 사상하여 형태를 기술하는 방법을 제안한다. 특징 공간을 나타내는 새로운 좌표계는 무게중심으로부터의 상대거리와 윤곽선 세그먼트 곡률을 두 축으로 하는 직교 좌표계이다. 상대거리는 윤곽선 상의 임의의 한 점이 무게중심에서 얼마나 멀리 벗어나 있는지를 나타내는 값이고, 윤곽선 세그먼트 곡률은 세그먼트의 굴곡도를 나타내는 값이다. 특징 공간에 사상된 점들의 형태 기술은 메쉬 특징을 통해 이루어진다. 실험을 통해 제안된 형태 기술 방법이 회전 및 크기 변형에 강건함을 확인하였다.

• 한국측량학회지
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• 제28권3호
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• pp.353-359
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• 2010

본 논문은 Scale Invariant Feature Transform(SIFT) 기술자를 이용한 매칭 방법을 개선하여 고해상도영상에서 보다 많은 매칭쌍(tie points)을 추출함으로써 고해상도영상 자동기하보정의 결과향상을 목적으로 한다. 이를 위해 기준(reference)영상과 대상(sensed)영상의 특징점(interest points)간의 위치관계를 추가적으로 이용하여 매칭쌍을 추출하였다. SIFT 기술자를 이용하여 어핀(affine)변환계수를 추정한 후, 이를 통해 대상영상의 특징점 좌표를 기준영상 좌표체계로 변환하였다. 변환된 대상영상의 특징점과 기준영상의 특징점간의 공간거리(spatial distance)정보를 이용하여 최종적으로 매칭쌍을 추출하였다. 추출된 매칭쌍으로 piecewise linear function을 구성하여 고해상도 영상간 자동기하보정을 수행하였다. 제안한 기법을 통하여, 기존 SIFT 기법에 의해 추출한 결과에 비해 영상 전역에 걸쳐 고르게 분포된 다수의 매칭쌍을 추출할 수 있었다.

• 대기
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• 제20권3호
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• pp.343-353
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• 2010

A regional wind network with complex surface conditions must be designed with sufficient space and time resolution to resolve the local circulations. In this study, the spatial variations of the wind field observed in the Seoul and Jeju regional networks were evaluated in terms of annual, seasons, and months to assess the spatial homogeneity of wind fields within the regional networks. The coherency of the wind field as a function of separation distance between stations indicated that significant coherency was sometimes not captured by the network, as inferred by low correlations between adjacent stations. A meso-velocity scale was defined in terms of the spatial variability of the wind within the network. This problem is predictably most significant with weak winds, dull prevailing wind, clear skies and significant topography. The relatively small correlations between stations imply that the wind at a given point cannot be estimated by interpolating winds from the nearest stations. For the Seoul and Jeju regional network, the meso-velocity scale has typically a same order of magnitude as the speed of the network averaged wind, revealing the large spatial variability of the Jeju network station imply topography and weather. Significant scatter in the relationship between spatial variability of the wind field and the wind speed is thought to be related to thermally-generated flows. The magnitude of the mesovelocity scale was significantly different along separation distance between stations, wind speed, intensity of prevailing wind, clear and cloudy conditions, topography. Resultant wind vectors indicate much different flow patterns along condition of contributing factors. As a result, the careful considerations on contributing factors such as prevailing wind in season, weather, and complex surface conditions with topography and land/sea contrast are required to assess the spatial variations of wind field on a regional network. The results in the spatial variation from the mesovelocity scale are useful to represent the characteristics of regional wind speed including lower surface conditions over the grid scale of large scale atmospheric model.

• 천문학회보
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• 제42권2호
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• pp.47.2-47.2
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• 2017

We investigate the environmental effects on galaxy spin using the sample of ~1100 galaxies from the first public data of MaNGA integral field unit survey. We determine the spin parameter ${\lambda}_{Re}$ of galaxies by analyzing the two-dimensional stellar kinematic measurements within the effective radius, and study its dependence on the large-scale (background mass density determined with 20 nearby galaxies) and small-scale (distance to and morphology of the nearest neighbor galaxy) environments. We first examine the mass dependence of galaxy spin, and find that the spin parameter decreases with stellar mass at log ($M_{\ast}/M_{\odot}$) > 10, consistent with previous studies. We then divide the galaxies into three subsamples using their stellar masses to minimize the mass effects on galaxy spin. The spin parameter of galaxies in each subsample does not change with the background density, but do change with the distance to and morphology of the nearest neighbor. The spin parameter increases when late-type neighbors are within the virial radius, and decreases when early-type neighbors are within the virial radius. These results suggest that the large-scale environments hardly affect the galaxy spin, but the effects of small-scale environments such as hydrodynamic galaxy-galaxy interactions are substantial.

• 설비공학논문집
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• 제27권8호
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• pp.418-425
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• 2015

The Korean government plans to establish large-scale horticultural facilities using reclaimed land to improve the competitiveness of the national agricultural sector at the government level. One of the most significant corresponding problems is the ongoing dependence of these facilities on fossil fuel, whereby constant heating is necessary during the winter season to provide the necessary breeding conditions for greenhouse crops. In particular, high-level energy consumption is incurred from the use of heating-related coverings with large heat-transmission coefficients such as those composed of vinyl and glass. This study investigated the potential applicability of waste-incineration heat for use in large-scale horticultural facilities by evaluating the hot-water temperature, heat loss, and available greenhouse area as functions of the distance between the incineration facility and the greenhouse. In conclusion, waste-incineration heat from a HDPE pipe can heat a horticultural facility of 10 ha if the distance is less than 8 km.

• Journal of Ecology and Environment
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• 제45권3호
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• pp.97-104
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• 2021

Background: Asarum sieboldii Miq., a species of forest understory vegetation, is an herbaceous perennial belonging to the family Aristolochiaceae. The metapopulation of A. sieboldii is distributed sparsely and has a short seed dispersal distance by ants as their seed distributor. It is known that many flowers of A. sieboldii depend on self-fertilization. Because these characteristics can affect negatively in genetic structure, investigating habitat structure and assessment of genetic structure is needed. A total of 27 individuals in a valley were sampled for measuring genetic diversity, genetic distance, and genetic differentiation by RAPDPCR. Results: The habitat areas of A. sieboldii metapopulation were relatively small (3.78~33.60 m²) and population density was very low (five to seven individuals in 20×20 m quadrat). The habitat of A. sieboldii was a very shady (relative light intensity = 0.9%) and mature forest with a high evenness value (J = 0.81~0.99) and a low dominance value (D = 0.19~0.28). The total genetic diversity of A. sieboldii was quite high (h = 0.338, I = 0.506). A total of 33 band loci were observed in five selected primers, and 31 band loci (94%) were polymorphic. However, genetic differentiation along the valley was highly progressed (G_st = 0.548, N_m = 0.412). The average genetic distance between subpopulations was 0.387. The results of AMOVA showed 52.77% of variance occurs among populations, which is evidence of population structuring. Conclusions: It is expected that a small-scale founder effect had occurred, an individual spread far from the original subpopulation formed a new subpopulation. However, geographical distance between individuals would have been far and genetic flow occurred only within each subpopulation because of the low density of population. This made significant genetic distance between the original and new population by distance. Although genetic diversity of A. sieboldii metapopulation is not as low as concerned, the subpopulation of A. sieboldii can disappear by stochastic events due to small subpopulation size and low density of population. To prevent genetic isolation and to enhance the stable population size, conservative efforts such as increasing the size of each subpopulation or the connection between subpopulations are needed.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.57-60
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• 2003

As the business dependency to information systems and the frequency of the large scale disasters increase, implementing the disaster recovery center has been a common practice. However, since there has been little quantitative decision method for the distance between the data center and the disaster recovery center, the distance decision has been commonly made by qualitative guidelines. In this research, the decision method for the optimal distance between the data center and the disaster recovery center is developed, using the cost analysis including the operation cost and the expected disaster cost. An illustrative numerical example is provided.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.119-130
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• 2021

This study aimed at Evaluate Students' Interaction and Happiness in Distance Learning Among Students with Learning-Difficulties, by identifying the level of students' interaction in distance education and differences between them, as well as its impact on their happiness to learn. To achieve the aim of the study, two scales were designed for this purpose and were applied to a sample consisting of (310) individuals. The results showed that the level of students' interaction through the e-learning platform was at a high level. The results also showed that there was no statistically significant difference between the mean scores of males and females in the scale of students' interaction through the e-learning platform. There was no statistically significant difference between them in their happiness for distance learning via the online platform. There were also no statistically significant differences related to the grade variable in the level of interaction through the electronic platform and in the happiness to learn, while there was a positive statistically significant effect of interaction through the electronic platform on students' happiness to learn.

• 한국군사과학기술학회지
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• 제20권2호
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• pp.238-245
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• 2017

This paper deals with the scale effects of warhead on concrete penetration. We investigated the scale effects using finite element analysis and Young's penetration equation. As the scale of penetration test decreases, the strain rate effects of target increases, and then strength of concrete target increases. This means the residual velocity and penetration depth of warhead decreases as the test model size decreases. Young's penetration equations are transformed with various penetrator mass and scale cases as a function of scale ratio. Penetration distance and residual velocity are not simply changed by the geometric scaling law.