• 소음진동
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• 제3권1호
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• pp.39-46
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• 1993

The seismic qualification for the class 1E battery of Korea Multipurpose Research Reactor was accomplished by the analysis as well as testing. The full rack consists of 4 similar sections of typical frame structure and contains 60 cells. However, since the seismic qualification was required on the frame structure and only on 3 aged ones among 60 dells, 2 sections of the full rack were assembled as a test rack with 28 cells including the 3 aged cells for an economic test. Seismic analysis for the full rack was carried out using the finite element program ANSYS. The modal parameters identified from the resonance search thest on the test rack were used to the seismic analysis of the full rack. It was confirmed that the test rack could represent the full rack with regards to seismic responses and function of cells, and that the full rack and aged cells were qualified to the given seismic test requirements.

• 한국화재소방학회논문지
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• 제32권1호
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• pp.66-75
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• 2018

랙크 내 설치되는 차단막은 초기 화재확산을 지연시키는데 큰 역할을 담당하고 있으나 소화를 목적으로 설치되는 천장형 스프링클러의 입장에서는 소화수의 원활한 공급에 장애물로서 비춰질 수도 있다. 이에 In-Rack 스프링클러와 차단막을 동시에 적용하는 방법 등이 제시되고 있으나 차단막의 설치조건에 따른 화재확산 지연성능 및 In-Rack 스프링클러에 미치는 영향 등에 관한 연구는 부족한 실정이다. 이에 본 연구에서는 축소모델 화재실험을 통해 차단막의 설치조건에 따른 화재확산 지연성능과 In-Rack 스프링클러에 미치는 영향 등을 분석하였다. 그 결과, 랙크 내에 수평과 수직 차단막을 동시에 설치한 경우, 4배 이상의 화재확산 지연성능이 발휘되는 것을 확인하였으며, 구획화로 인한 구획 내 온도 상승 또한 약 2~3배 가량 높은 것으로 나타나 In-Rack 스프링클러가 조기에 작동될 수 있도록 유도하는 긍정적인 효과 또한 존재하는 것으로 나타났다.

• 한국안전학회지
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• 제28권6호
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• ETRI Journal
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• 제32권6호
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.

• 한국수산과학회지
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• 제50권3호
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• pp.263-269
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• 2017

The mineral contents, and free amino acid, and fatty acid composition of rack and bag or suspended cultured oysters Crassostrea gigas were compared. The moisture content did not change much from 82.8% to 86.3% in the different culture methods. The glycogen level was low 4.7% during rack and bag culture but high 7.2% during suspended culture. The sodium level was the highest during suspended culture, while copper and zinc level were highest during rack and bag culture. The taurine level was 1,385-1,375 mg/100 g in oyster cultured using the rack and bag method, but that in the market sample was lowest at 1,015.8 mg/100 g. Hydroxyproline, glutamic acid, proline, glycine, and alanine were detected at high levels in the experimental oysters. The polyunsaturated fatty acid content was similar among samples. The docosahexaenoic acid level was 14% with rack and bag culture and 12% with suspended culture, whereas the eicosapentaenoic acid level was 15% with rack and bag culture and 20% with suspended culture. The atherogenic index (AI), thrombogenicity index (TI), and hypocholesterolemic/ hypercholesterolemic (h/H) ratio were important factors in the nutritional evaluation. The AI and TI values were 0.5-0.2, and the h/H ratio were 2.0 and 2.4 with the rack and bag and suspended culture, respectively.

• 한국패류학회지
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• 제29권1호
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• pp.43-50
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• 2013

We investigated the growth performance of oysters (initial shell height $57.5{\pm}8.5$ mm) under differing conditions of tidal exposure time and culture rack height in an experiment that commenced in April, 2011. Significant differences were observed in shell height from June 2011, in total weight from August, and in meat weight from September. Fatness tended to decrease during the experimental period, but was not significantly different at the end of the experiment. Significant differences in survival rates were mainly observed from June to August. After September, further changes were not observed in any experimental treatment group. The greatest growth potential ($L_{\infty}$) and survival rate were observed at a sea level of approximately 116 cm. The results indicate that in the study area the use of oyster culture conditions involving 1 or 2 h of tidal exposure and 60 - 70 cm rack height could result in oysters reaching the favored commercial half shell size within 14 months, with > 80% survival.

• 한국건설관리학회논문집
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• 제24권4호
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• pp.25-34
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• 2023

본 연구의 목적은 플랜트 건설에서 현장시공과 모듈시공에 대한 공사비를 산정하여 비교하는 것으로 공사비를 산정하는 대상을 Pipe Rack으로 한정하였다. 이에, 현장시공으로 준공된 국내 석유화학플랜트 건설사업 1곳을 사례로 선정한 후 비용자료를 조사하여 도출된 결과는 다음과 같다. Pipe Rack의 현장시공에 대한 직접공사비는 560억원으로 Steel Structure 251억원, Piping 308억원이며, 모듈시공에 대한 직접공사비는 607억원으로 Steel Structure 238억원, Piping 297억원으로 산정되었다. 또한, 현장시공과 모듈시공의 증감률을 비교해 보면, 재료비 1.9%, 경비 192.1% 증액되었으나, 노무비는 -9.1% 감액되어, 전체 직접공사비는 8.4%(47억원)가 증액되었다. 그리고 공사원가는 현장시공이 761억원, 모듈시공은 810억원으로 모듈시공이 6.4%(49억원) 증액되는 것으로 나타났다. 이와 같은 결과는 Pipe Rack을 모듈로 시공하는 경우 공사비가 증감되는 현황을 확인하기 위한 참고자료로 활용이 용이한 반면에, 모듈시공에 따른 간접적인 효과(노무인력 감소, 안전사고 발생 감소, 공사기간 단축 등)에 대한 연구가 필요하다.

• 한국화재소방학회논문지
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• 제31권4호
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• pp.71-79
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• 2017

적재밀도가 높으며 수직적인 적재형태를 가지는 랙크식 창고는 화재발생 시 그 피해가 매우 심각하다. 이에 미국, 일본에서는 자국의 랙크식 창고 실정에 맞는 In-Rack 스프링클러 및 수평차단막 등을 적용하여 화재확산을 최소화하는데 노력하고 있으나 국내의 경우, 그와 관련한 연구 및 제도가 전무한 실정이다. 이에 본 연구에서는 발화위치 및 수평차단막 설치간격에 따른 화재특성 확인을 위해 국내 랙크식 창고 실정을 반영한 표준랙크를 대상으로 축소모델 화재시험을 수행하였다. 그 결과, 수평차단막의 설치간격을 밀접하게 또는 빈번하게 할수록 약 30%씩의 수직 화재확산 억제성능이 발휘되는 것을 확인하였다. 아울러 수평차단막을 경계로 상하부의 온도를 측정한 결과, 차단막이 설치된 경우가 그렇지 않은 경우에 비해 온도분포가 약 2~4배 이상 높은 것으로 나타나 수평차단막의 설치가 In-Rack 스프링클러의 조기 작동에 도움을 줄 것으로 판단된다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.469.2-469
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• 2001

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.1-4
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• 2000

In general, under the concept of unit load, Automated Storage/Retrieval Systems (AS/RS) have the rack of equal sized cells. However, they are inadequate and inefficient meeting the various sizes of customers' demands in today's business environment. Higher utilization and flexibility of warehouse storage can be achieved by using AS/RS with tile rack of modularized cell. In this paper, the model of AS/RS with the rack of modularized cell is proposed, and the effectiveness of proposed model is presented by way of numerical examples. The model developed in this research, as one type of AS/RS that is more flexible to the size and has higher space utilization than those of existing rack structure, could every useful for the storage of heterogeneous unit load sizes.