• 대한기계학회논문집B
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• 제25권12호
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• pp.1748-1755
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• 2001

The shell and tube heat exchangers were introduced to apply to a big capacity condenser and a high pressure feed water heater for power plant in the beginning of 1990s. Design and manufacturing technology fur shell and tube heat exchangers have been developed until now. But it is very difficult to calculate the expected performance characteristics of the shell and tube heat exchanger, because there are many design parameters to be considered according to internal structure and the shell side heat transfer mechanism complicately related to the design parameters. Design parameters to be considered in the design stage of shell and tube heat exchanger are shell and tube side fluids, flow rate, inlet and outlet temperature, physical properties, type of heat exchanger, outer diameter, thickness, length of tube, tube arrangement, tube pitch, permissive pressure loss on both sides, type of baffle plate, baffle cutting ratio. The propose of study is an analysis TEMA(Tubular Exchanger Manufacturers Association) E shell and tube heat exchanger performance with changing a number of baffles(3, 5, 7, 9, 11) and tubes(16, 20) and determined optimal baffle spacing.

• 터널과지하공간
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• 제21권6호
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• pp.427-438
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• 2011

세그먼트 라이닝은 쉴드터널에서 공사 중의 안정성을 확보하고 영구적인 터널 라이닝으로 사용되는 중요한 구조체이다. 더욱이 세그먼트 라이닝은 쉴드터널의 공사비에서 가장 큰 비중을 차지하기 때문에, 세그먼트의 경제성 향상을 위한 기술적인 개선 노력들이 이루어지고 있다. 따라서 본 연구에서는 경제적인 세그먼트 라이닝의 시공을 위한 고성능 세그먼트의 최신 개발 동향을 조사 및 분석하여 세그먼트의 기술개발 방향을 제시하고자 하였다. 또한 설계단계에서 세그먼트의 주요 설계사항들을 개략적으로 추정하는데 활용하기 위하여, 전 세계 2,100여개 세그먼트 자료들을 조사하고 이를 기반으로 세그먼트 라이닝 외경, 세그먼트 주요 형상치수 및 세그먼트 재질들에 대한 통계분석을 실시하였다.

• 한국초지조사료학회지
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• 제3권2호
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• pp.86-91
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• 1983

Orchardgrass 단파초지(單播草地)의 최고총생산수량(最高總生産收量)과 질적향상(質的向上)을 위한 수확적기(收穫適期)를 장(張) (1971)의 총생산수(總生産收) 양식(量式)에 의하여 이론적(理論的)으로 분석(分析) 연구(硏究)하였다. Orchardgrass초지(草地)의 형태학적(形態學的) 특징(特徵)으로 0% 개화기(開花期)에 목확(牧穫)하는 것이 IDV와 CP의 높은 수준(水準)과 함께 최대건물생산량(最大乾物生産量)을 달성(達成)할 수 있다는 것으로 판단(判斷)되었다. 그러나 orchardgrass는 1차예취후(次刈取後)에는 개화(開花)하지 않기 때문에 그 이후(以後)에는 극대치(極大値)의 감치기로 대치(代置)할수 있다고 판정(判定)되었다.

• 한국식품조리과학회지
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• 제23권5호
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• pp.749-760
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• 2007

The purpose of this study was to evaluate the microbiological quality of non-heat-processed foods and the effects of HACCP implementation. Here, cabbage salad and cucumber&onion salad were selected and we investigated HA(Hazard Analysis) by checking microbiological quality, time and temperature, pH, and water activity at each processing stage. Thus, the receiving of spices and dressings, washing and sterilizing, cutting, cooking, and serving stages were all considered CCPs. Before implementing HACCP, microbial analysis showed that standard plate counts and coliform counts were higher than standard levels in most of the raw ingredients of each menu, as well as during the production process. The microbiological quality of the utensils and employee's hands used during cooking indicated levels requiring direct management. Evaluations of falling bacteria-in the foodservice establishment work areas ranged from $2{\sim}12CFU/plate$. However, after HACCP implementation, microbiological levels improved to standard levels fly sanitation education. Also, the number of falling bacteria were lower than before implementing HACCP. Therefore, it is essential the foodservice operations make efforts to implement HACCP, so that microbiological hazard levels are lowered and hygienic status improved.

• 동굴
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• 제61호
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• pp.65-82
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• 2000

The remarkable development of information technology today is significantly increasing the desire for related services as it allows one to process and transmit information fast and accurately as well as in an efficient way. Particularly, the spread of the Internet even changes our life pattern, not to mention allowing us to provide or share information. One of the most typical example is electronic commerce. The e-commerce industry, which is build upon informations super high way, is growing rapidly, backed on the development of communications technology and the combination of various media. Companies are active In embracing and utilizing the cutting-edge information technology, whereas the tourism industry in general is still at a rudimentary stage. Therefore, it is expected that the industry will harness e-commerce in many aspects. Tourism, in its characteristic, has a variety of sectors, and cross-sector cooperation is essential. Therefore, the industry can provide better services by connecting or integrating network systems and taking advantage of e-commerce, while it is of no less importance to have informal ion system for promoting products. This thesis will look into and the basic concept and role of e-commerce as well as the existing tourism information system. It will also study ways to make good use of e-commerce by adopting it into the tourism information system.

• 건축역사연구
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• 제4권1호
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• pp.93-112
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• 1995

The wooden pagoda was first appeared in about late 4th century in Korea. And between the late 6th century and the eary 7th centry, the multistoried wooden pagoda was replaced with the stone pagodas, in order to improve their stability and durability. In Three-kingdom and Unificated-Silla period, there are two types of stone stupas in Korea. The one is Paekche(百濟)style, and the other is Silla(新羅) style stone pagoda. These two styles are basically different in each part like podium, roof stone, body stone, structure and the others. Two types of stupas are distributed in two regions which devided into the East(Silla territory) and West(Paekche territory) in the Korean peninsular. The origin of the Korean stone pagoda can be traced to the Paekche dynasty and Silla dynasty. The former were the result of the careful study of their skillful wooden pagodas, where the latter were actualy originated from copying their sundried brick pagodas with stone. Two important pagodas of the primitive stage are the stone pagoda of Miruksa(彌勒寺) temple in Iksan and Bunhwangsa(芬皇寺) temple in Kyungju. These two pagodas are compared with each other in the style of their construction. Silla style have sharp straight lines and short distance between roof stone and eaves. They give us strong as well as intelletural feeling. Howerever, Paekche style has curved lines and dull angles of cutting area of stone, they give us soft feeling.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.15-18
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• 2009

Due to its high dependency of manpower, construction work has several difficulties in terms of quality control, imbalance of supply and demand of qualified manpower, safety management for them and improvement of production. Such problems related to the management can be at some degree solved by introducing an automation facility. Since the unique environment of a construction site in the past was not structured, it is very hard to introduce a facility to automate construction work from operation of the equipment to assignment of where to work. This is a preliminary research for automation of construction work. In this study, the trend of development of a cutting-edge technology, RTLS, was researched and analyzed in order to review the possibility of utilizing RTLS in construction work and present a control mechanism for construction equipment. Although the presented mechanism is at the concept stage, which still has lots of restrictions to be solved, the application of the RTLS will be very much feasible. That is, if linkage of the study between the RTLS and the automation of construction is built, it will be expected to contribute to many fields such as cost reduction through efficient and systemic management, the reduction of construction period and precise construction as well as raising the level of the automation of domestic construction work.

• 한국조경학회지
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• 제31권3호
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• pp.114-124
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• 2003

The management methods of rooftop greening must be get ready without delay, Because rooftop greening has been generalized owing to the supporting project of The Seoul Metropolitan Government. Because most of the rooftop greening system is a recently-constructed low-management type, management methods should be made to suit it. This study is intended to set up a program for low-management rooftop greening based on "Choroktteul", the low management type of rooftop peening on the roof of one of the buildings in Seoul City Hall. Through monitoring, we found that most of the planted plants grew well but a few species needed physical management. We also found that invasive species(62 sp.) were 1.5 times as many as the planted plants. Most of the invasive plants were exotic species that need to be managed. The physical management methods were "pulling up" and "cutting". These methods should be carried out according to the growth stage. It was judged that a biological-ecological management program should be prepared through the long-period of monitoring and experiment. System methods such as guidelines of management program through monitoring was also required due to the emphasis on public ownership among the managers of the invasive species.

• 한국정밀공학회지
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• 제22권6호
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• pp.222-231
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• 2005

Recently, life cycle and lead-time of products have been shortened with the demand of customers. Therefore, it is important to reduce time and cost at the stage of manufacturing trial molds. In order to realize a three-dimensional shape on CAD, the machining process has been widely used because it offers practical advantages such as precision and versatility. However, the traditional machining process needs a large amount of time in cutting a product and the remained material causes trouble such as inconvenience for clarity. In this work, a new rapid manufacturing process using the hot tool, Rapid Heat Ablation process, has been developed to overcome such limitations. While the hot tool moves the predetermined path, the heat of the tool decomposes the remained material. The radius of heat affect ed zone related to process parameters was investigated through experiments to improve the quality of ablated parts. In order to examine the applicability of the proposed process, three-dimensional shapes such as hemisphere and standard test part, wereablatedutilizingtheapparatus.

• Geomechanics and Engineering
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• 제30권4호
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• pp.363-372
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• 2022

One of the most frequent issues in tunnel excavation is the collapse of rock blocks and the dropping of rock fragments from the tunnel face. The tunnel face can be reinforced using a number of techniques. One of the most popular and affordable solutions is the use of face longitudinal dowels, which has benefits including high strength, flexibility, and ease of cutting. In order to examine the reinforced face, this work shows the longitudinal deformation profile and ground response curve for a tunnel face. This approach is based on assumptions made during the analysis phase of problem solving. By knowing the tunnel face response and dowel behavior, the interaction of two elements can be solved. The rock element equation derived from the rock bolt method is combined with the dowel differential equation to solve the reinforced ground response curve (GRC). With a straightforward and accurate analytical equation, the new differential equation produces the reinforced displacement of the tunnel face at each stage of excavation. With simple equations and a less involved computational process, this approach offers quick and accurate solutions. The FLAC3D simulation has been compared with the suggested analytical approach. A logical error is apparent from the discrepancies between the two solutions. Each component of the equation's effect has also been described.