• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.59-67
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• 2012

In this paper, performances of solar hot water supply systems are parametrically analyzed with the variations of solar collector area, slope of collector and volume of storage. All simulations are conducted by using TRNSYS computer program. Average solar fractions, collector efficiencies and temperatures of storage are investigated monthly as well as annually. For system analysis, the maximum value of monthly average solar fractions has a limitation of 90 percent. As a result, the designed solar thermal system with $6m^2$ collector area, $50^{\circ}$ slope and $0.36m^2$ storage volume could provide almost an annual average solar fraction of 72 percent. By increasing the storage volume to $0.42m^2$, the annual solar fraction of system increases up to 73 percent.

• 한국IT서비스학회지
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• 제7권1호
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• pp.195-204
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• 2008

As the dependency to network system and demands of efficient storage systems rapidly grows in every networking filed, the current trends initiated by explosive networked data grow due to the wide-spread of internet multimedia data and internet requires a paradigm shift from computing-centric to data-centric in storage systems. Furthermore, the new environment of file systems such as SAN(Storage Area Network) is adopted to the existing storage paradigm for providing high availability and efficient data access. We describe the design issues and system components of $SANique^{TM}$, which is the cluster file system based on SAN environment. We, especially, present the comparative results of performance analysis for the intensive I/O test by using the DBMSs that are operated at the top of cluster file system $SANique^{TM}$, EXT3 and NFS respectively.

• 한국식생활문화학회지
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• 제39권3호
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• pp.147-155
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• 2024

This study analyzed the changes in the nutritional components, properties, physicochemical properties, general bacteria, and lactic acid bacteria of pickled cabbage depending on the cultivation area. An analysis of the nutritional composition on the first day of storage showed no significant difference in the calories, carbohydrates, protein, fat, and dietary fiber contents regardless of the cultivation region, but regional differences were observed in the vitamin C content in the order of Andong > Pyeongchang > Haenam. The total free amino acid content appeared in the order Andong > Pyeongchang > Haenam, and the GABA (γ-amino-n-butyric acid) content appeared in the order Haenam > Andong > Pyeongchang. In addition, pickled cabbage was observed on the 1^st, 5^th, and 10^th days of storage at 4℃. No significant change in appearance was observed on the 1^st and 5^th days, but changes were observed on the 10^th day. Regardless of the cultivation area, the salinity (p<0.05) and pH (p<0.05) decreased significantly as the storage period increased, while the sugar content (p<0.05) and acidity (p<0.05) increased significantly. The general bacteria (p<0.05) and lactic acid bacteria (p<0.05) counts increased significantly as the storage period increased, irrespective of the cultivation region.

• 설비공학논문집
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• 제25권11호
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• pp.578-584
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• 2013

Vertical open display cases are widely used in shopping malls, supermarkets, or retail stores to sell frozen and refrigerated products. Open display cases use air curtains to maintain a reasonable temperature within the storage space, prevent insects from breaking in, and reduce energy usage. In this research, computational fluid dynamics was used to find the optimal condition for reducing energy by considering various conditions such as discharge speed or temperature of air curtains. Results of the study showed that the amount of energy consumed in the display cabinet is influenced by the discharge speed and temperature of the slots installed on the upper area and the amount of air supplied to the storage area inside the shelf. This shows that the amount of discharged air supplied from the storage area influences the formation of air curtain and also the amount of energy consumption. As a result of this study, we learned that the amount of energy used can be reduced by increasing the amount of discharged air within the storage area and enhancing back pressure.

• 한국가시화정보학회지
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• 제22권2호
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• pp.11-19
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• 2024

We performed numerical simulations on a C-type liquid hydrogen (LH2) storage tank for commercial vehicles to reduce evaporation rates by manipulating vortical structures. Owing to external heat, natural convection occurs inside the tank, leading to the enhanced evaporation of LH2. We observed that the regions of high magnitude vorticity correlate with those of high evaporation rates. Specifically, vortical structures in the side section area show higher vorticity magnitude and evaporation rates compared to those in the midsection area. To suppress these vortical motions, we installed an array of ribs at intervals corresponding to the mean diameter of the vortical structures. As a result, the area occupied by vortical structures in the side section area decreased, leading to a reduction in evaporation speed by approximately 2.3 times. This study elucidates the internal evaporation mechanism in storage tanks from the perspective of flow structures and potentially contributes to minimizing the boil-off rate in cryogenic storage tanks.

• 한국환경복원기술학회지
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• 제22권6호
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• pp.1-14
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• 2019

Carbon storage is one of the regulating ecosystem services provided by urban street trees. It is important that evaluating the economic value of ecosystem services accurately. The carbon storage of street trees was calculated by measuring the morphological parameter on the field. As the method is labor-intensive and time-consuming for the macro-scale research, remote sensing has been more widely used. The airborne Light Detection And Ranging (LiDAR) is used in obtaining the point clouds data of a densely planted area and extracting individual trees for the carbon storage estimation. However, the LiDAR has limitations such as high cost and complicated operations. In addition, trees change over time they need to be frequently. Therefore, Structure from Motion (SfM) photogrammetry with unmanned Aerial Vehicle (UAV) is a more suitable method for obtaining point clouds data. In this paper, a UAV loaded with a digital camera was employed to take oblique aerial images for generating point cloud of street trees. We extracted the diameter of breast height (DBH) from generated point cloud data to calculate the carbon storage. We compared DBH calculated from UAV data and measured data from the field in the selected area. The calculated DBH was used to estimate the carbon storage of street trees in the study area using a regression model. The results demonstrate the feasibility and effectiveness of applying UAV imagery and SfM technique to the carbon storage estimation of street trees. The technique can contribute to efficiently building inventories of the carbon storage of street trees in urban areas.

• 한국농공학회지
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• 제25권4호
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• pp.29-37
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• 1983

This study was carried out not only to prepare available materials that can be utilized in basic planning of irrigation reservoirs, but also to contribute to the study on countermeasures for reasonable irrigation water development in Korea in the future, through the investigation for the structural characteristics of reservoirs and their change trend by an epoch. During this study 123 sites of sample reservoirs were analysed in their dimensions of physical constituent factors. The physical characteristics and their change trends revealed by this study are summarized as follows: 1. For the irrigation earth dam in Korea the correlation between dam volume (v) and dam height & length (H$^2$L) can be described as the formula of v=1. 434H2L~17, 300 (r=0. 933), from which embankment amount is assumed to be quickly estimated under determined dam height and length of the proposed reservoir. 2. The ratio of dam volume to dam height & length ranges approximately from 0.5 to 3 (1.7 in average), that of storage capacity to dam volume 2 to 10 (8.4 in average), that of irrigation area to full water surface area 5 to 20 (13 in average) and that of catchment area to irrigation area 2 to 5 (4 in average). Though correlation between dam volume and dam height & length is high, that between others is relatively low. 3. Average storage depth ranges approximately from 4m to l0m (6.6m in average), unit storage capacity 0. 4m to 0. 8m (0.54 in average) and shape factor of dam 5 to 20 (10.5 in average). 4. The more recently planned the reservoirs were, the less storage capacity, dam volume, full water surface and dam shape factor they have. 5. The more recently planned the reservoirs were, the larger storage depth and unit storage capacity they have.

• 디지털융복합연구
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• 제17권7호
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• pp.59-71
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• 2019

유통물류센터는 재고를 보유하고 있어 효율적인 보관면적에 관한 설계는 매우 중요하다. 이에 본 연구는 표준 파렛트 유닛로드 이용을 고려한 유통물류센터의 최적 보관면적 산출방안 제시를 연구 목적으로 하며, 연구결과는 다음과 같다. 첫째, 국내에서 주로 사용되는 T-11형과 T-12형 파렛트를 보관하는 표준 랙 모듈을 정의하였다. 둘째, 다양한 파렛트 운반 장비를 조사 및 분석하여, 유형별 표준 운반장비 작업통로를 정의하였다. 그리고 최종으로 보관 공간 내에서 랙 모듈 배치 시 발생할 수 있는 비활용 공간 최소화 방안 제시와 함께 유통물류센터 보관 공간에 대한 손쉬운 최적면적 산출 방안을 제안하였다는 측면에서 큰 시사점을 갖는다. 향후 연구에서는 Mini-Load용 표준 랙 모듈 및 GTP(Goods to Person) 피킹 시스템 등 최근 물류 기술이 반영된 표준화된 전체 물류센터 레이아웃 배치에 관한 연구가 필요하다.

• 한국재난정보학회 논문집
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• 제16권1호
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• pp.79-86
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• 2020

연구목적: 본 연구에서는 Sentinel-1 위성이 촬영한 영상을 활용하여 천안지역 저수지의 저수량을 추정하는 모형을 개발하였다. 연구방법: 총 3개의 저수지를 대상으로 연구를 진행하였으며, 3개 저수지 모두 수위가 계측되고 있는 소규모 저수지이다. Sentinel-1 영상의 전 처리는 유럽항공우주국(ESA, European Space Agency)에서 배포한 SNAP을 활용하였으며, 임계치 분류 방식에 의해 수체를 구분하여 저수면적을 추정하였다. 추정한 저수면적에 대해서는 인공위성이 촬영한 날짜와 동일한 날짜에 드론으로 촬영하여 저수면적을 비교하였다. 저수지 저수면적을 추정한 것과 관측유량 자료와의 관계식을 도출하여 저수량 추정모형을 구축하였다. 연구 결과 및 결론: 위성영상분석을 통해 추정한 저수량 값은 실제 계측자료와 유사한 값을 가지는 것을 확인할 수 있었다. 다만, 여름철 저수지의 녹조, 부착돌말류 등으로 인해 저수면적의 과소 추정과 위성영상 해상도로 인한 저수면적이 10,000㎡ 이하인 저수지는 위성영상으로는 탐지가 어려운 문제점이 존재하는 것을 확인하였다.

• 한국수자원학회논문집
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• 제40권7호
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• pp.523-532
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• 2007

1974년 한강홍수예보시스템을 구축한 이후로, 저류함수법을 근간으로 하는 홍수예보시스템이 주요하천을 대상으로 운영되고 있다. 1961년 목촌준황(木村俊晃)에 의하여 제안된 저류함수법은 저류함수를 기본식으로 이용하고 있다. 저류함수법에서는 유역을 유출역과 침투역으로 구분하고, 누가우량이 포화우량을 초과하기 전까지는 유출역에서만 유출이 발생하고, 포화우량을 초과한 후부터 침투역에서도 유출이 발생하는 것으로 가정하였고, 이때 유출역의 면적이 일정하므로 유출률은 일정한 것으로 가정하였다. 또한 유출역과 침투역의 유출량을 분리하여 계산하며, 이는 비선형저수지의 특성을 고려하면 불합리하다. 본 연구에서는 저류방정식과 연속방정식을 이용한 수정된 저류함수법을 제시하였으며, 유효우량은 SCS 초과우량산정방법을 이용하였다. 낙동강유역의 위천을 대상으로 수정된 저류함수법을 적용하였으며, 목촌준황(木村俊晃) 저류함수법에 비하여 첨두홍수량 산정에 개선된 결과를 보였으며, 매개변수의 감소로 적용성을 개선하였다.