• 한국가스학회지
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• 제20권1호
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• pp.7-12
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• 2016

천연가스는 장거리 수송을 위해서는 액화가 필수적으로 이루어진다. 액화공정 내 압축기에서 특히 많은 동력이 요구되며, 동력을 공급하기 위해서는 동력기가 필요하다. 여러 가지 동력기 중 어떠한 동력기를 선택하느냐에 따라 동력 공급에 필요한 비용이 변하게 된다. 본 연구에서는 최소의 비용으로 천연가스 액화공정에 동력을 공급하는 최적의 동력기 선택을 위해 최적화를 수행하였다. 또한 가스전의 용량을 고려하여 일정한 가스전에서 천연가스가 추출부터 소멸될 때까지의 전체기간 동안에 추출되는 속도가 변경되는 시나리오를 구성하였다. 공정모사를 통해 동력기 장치의 비용과 운전비용 간의 상관관계를 예측하였으며, 장치의 수명 등을 고려하여 모델링하였다. 그 결과 최대 6.4%의 비용을 감소하는 최적의 동력기 모델을 설계하였다.

• 대한건축학회논문집:계획계
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• 제34권7호
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• pp.3-12
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• 2018

The present remodeling makes almost no difference from rebuilding as all the building materials are removed remaining frame structure only. And, in case of vertical extension of building, higher construction cost and safety problem occur. The Ministry of Land, Transport and Maritime Affairs, therefore, recommends customized remodeling that can be made in light of the resident' needs such as parking lot, elevator, bathroom, and room for the alternative of remodeling of vertical extension of building. The purpose of this study is to present real data that can be referred to the constructor's decision making before starting the remodeling, by investigating and analyzing the weight and importance between evaluation factors for customized remodeling at the completed time of remodeling. Accordingly, the factors were divided into environmental factor, social factor, and economical factor, and the survey was performed for the residents living in remodeling houses. In addition, for the professionals, AHP (Analytic Hierarchy Process) has been carried out for the priority in the customized remodeling. For environmental factor, the level of importance made difference from that before remodeling, except parking level. For social factor, every item, including psychological satisfaction and community satisfaction, made difference. For economical factor, the recognition level of importance in rent made difference, except sale price of the factor for price satisfaction. In case of the factor for cost satisfaction, it was checked that construction cost and administration cost both could be considered important. As a result of AHP, the most importantly emphasized item was construction cost, and sale price, administration cost, residence structure, and parking lot were followed by priority in order. This study could contribute to reliably settle down customized remodeling by giving reasonable and substantial help from the analysis of the differences in the customized remodeling items before/after the remodeling.

• 대한두개안면성형외과학회지
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• 제23권4호
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• pp.163-170
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• 2022

Background: Personal mobility devices (PMDs) have become an increasingly popular transport modality globally. With increasing social interest in and demand for PMDs, the number of individuals visiting emergency departments with PMD-related injuries has also increased annually. This study aimed to evaluate injury patterns and treatment costs for patients treated in the department of plastic surgery in a trauma center. Methods: In this retrospective study, data concerning patients with PMD-related injuries from January 2017 to December 2021 were reviewed. The data retrieved included age, sex, alcohol consumption, helmet use, the type of impact, onset of injury, place of first visit, type of injury, admission status, operation status, and treatment cost. Multiple linear regression analysis was performed to determine the effects of various factors on cost. Results: Data were collected from 93 patients. Until 2019, the annual number of PMD-related accidents was less than 10; however, this number increased sharply in 2020. The average cost of hospitalization was USD 7,698 whereas the average cost of non-hospitalization was USD 631. Only fractures had a significant association with total cost in linear regression analysis (p< 0.001). Conclusion: The prevalence of PMD use and related injuries requiring plastic surgery during the study period showed significant health and financial costs both to the patients involved and to society. This cost could be reduced through stricter regulations concerning PMD use, advocating the use of protective gear, and promoting greater awareness of safety measures and of the consequences of PMD-related accidents.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.94-101
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• 2020

본 연구는 기본형건축비 내 PHC-pile 공사비를 가산비로 제외함에 따라 분양가에 미치는 영향을 분석하였다. '20년 3월 이전 기본형건축비에는 15m PHC-pile 공사비가 포함되어 있었다. 그러나 분양가 심사에서 설계된 pile 물량을 고려하여 공사비를 조정해야 하지만, 이를 조정하지 않는 문제가 발생하였다. 이에 국토부에서는 '20년 3월 고시에서, PHC-pile 공사비를 기본형건축비에서 제외하고, 설계된 pile만을 가산비로 인정하도록 하였다. 따라서, 본 연구는 기존방식과 개선된 방식의 pile 공사비를 추정하고, 이를 비교함으로써 분양가에 미치는 영향을 분석하였다. 이를 위하여 최근 수도권에 분양된 7개 사례를 선정하여 PHC-pile 공사비를 추정하였다. 기존방식은 기본형건축비에서 pile 공사비가 차지하는 비율로 추정하였고, 개선된 방식은 설계내역서의 물량을 기반으로 예정가격산정기준을 적용하여 추정하였다. 그 결과 개선된 방식으로 pile 공사비를 산출할 경우 기본형건축비가 약 2~3% 하락하였다. 또한 PHC-pile 공사비를 제외한 분양가격과 수도권 분양가격을 비교한 결과 수도권 대비 약 1%정도 하락하는 것으로 나타났다. 본 연구를 통하여 기본형건축비 산출에 대한 이해를 높일 수 있을 것으로 기대한다. 마지막으로, 제도적인 개선을 통하여 국민 주거안정 도모에 기여할 수 있을 것으로 판단된다.

• 한국항해학회지
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• 제7권1호
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• pp.1-32
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• 1983

The delay due to congestion has recently attracted widespread attention with the analysis of over-all operation at the port. But, the complexity of the situation is evident in view of the large number of factors which impinge on the considerable end. Queueing theory is applicable to a large scale transportation system which is associated with arrivals of vessels in a large port. The attempt of this paper is to make an extensive analysis of the port transport system and its economic implications from the viewpoint that port is one of the physical distribution facilities and a kind of queueing system which includes ships and cargoes as port customer. By analyzing the real data on the Port of Pusan, it is known that this port can be represented as a set of multi-channel with identical setof Poisson arrival and Erlang service time, and also it is confirmed that the following formula is suitable to calculate the mean delay in this port, namely, $W_4={\frac{\rho}{\lambda(1-\rho)} {\frac{e_N(\rho{\cdot}N)}{D_{N-1}(\rho{\cdot}N)}$ where, ${\lambda}$: mean arrival rate $\mu$: mean servicing rate; N: number of servicing channel; ${\rho}$: utillization rate (${\lambda}/N{\mu}$) $e_N$: the Poisson function Coming to grips with the essentials of the cost of delay due to congestion, a simple ship journey cost model is adopted and the operating profit sensitivity to variation in port time is examined, and for purpose of a future development for port princing service the marginal cost is approximately calculated on the basis of queueing theory.

• Smart Structures and Systems
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• 제12권1호
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• pp.1-22
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• 2013

Magnetic nanoparticle based bioseparation in microfluidics is a multiphysics phenomenon that involves interplay of various parameters. The ability to understand the dynamics of these parameters is a prerequisite for designing and developing more efficient magnetic cell/bio-particle separation systems. Therefore, in this work proof-of-concept experiments are combined with advanced numerical simulation to design and optimize the capturing process of magnetic nanoparticles responsible for efficient microfluidic bioseparation. A low cost generic microfluidic platform was developed using a novel micromolding method that can be done without a clean room techniques and at much lower cost and time. Parametric analysis using both experiments and theoretical predictions were performed. It was found that flow rate and magnetic field strength greatly influence the transport of magnetic nanoparticles in the microchannel and control the capturing efficiency. The results from mathematical model agree very well with experiments. The model further demonstrated that a 12% increase in capturing efficiency can be achieved by introducing of iron-grooved bar in the microfluidic setup that resulted in increase in magnetic field gradient. The numerical simulations were helpful in testing and optimizing key design parameters. Overall, this work demonstrated that a simple low cost experimental proof-of-concept setup can be synchronized with advanced numerical simulation not only to enhance the functional performance of magneto-fluidic capturing systems but also to efficiently design and develop microfluidic bioseparation systems for biomedical applications.

• 한국항공운항학회지
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• 제25권4호
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• pp.111-123
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• 2017

This study aimed at finding the ways to improve competitiveness of Korean low cost carriers in the highly competitive air transport market by understanding the relation among the influence of prior knowledge, service quality on customer satisfaction and reuse intention. The result of the research is as the following. At first, the influence of prior knowledge on customer satisfaction and reuse intention was statistically significant. The result indicates that customers who have much prior knowledge are more likely to be satisfied and to reuse. Secondly, the test for finding out the influence of service quality on customer satisfaction and reuse intention was statistically significant also. Thirdly, the results revealed that customer satisfaction positively influenced reuse intension. The influence of service quality on customer satisfaction and reuse intention reached the same research result compared with the existing literature.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.2179-2183
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• 2009

As urbanization is progressed, the network for distributing water in a basin become complex due to the spatial expansion and parameter uncertainties of water supply systems. When a long range water supply plan is determined, the total construction and operation cost has to be evaluated with the system components and parameter uncertainties as many as possible. In this paper, the robust optimization approach of Bertsimas and Sim is applied in a hypothetical system to find a solution which remains feasible under the possible parameter uncertainties having the correlation effect between the uncertain coefficients. The system components to supply, treatment, and transport water are included in the developed water supply system and construction and expansion of the system is allowed for a long-range period. In this approach, the tradeoff between system robustness and total cost of the system is evaluated in terms of the degree of conservatism which can be converted to the probability of constraint violation. As a result, the degree of conservatism increases, the total cost is increased due to the installation of large capacity of treatment and transportation systems. The applied robust optimization technique can be used to determine a long-range water supply plan with the consideration of system failure.

• KEPCO Journal on Electric Power and Energy
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• 제3권1호
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• pp.49-56
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• 2017

In order to examine the feasibility of Carbon Capture & Sequestration, a major technological strategy for the national goal of greenhouse gas reduction, this paper studies the various methods and corresponding costs for the transportation of $CO_2$ captured at the domestic thermal power plants, as well as performing comparative analysis with overseas CCS demonstration projects. It is predicted that the investment cost would be about 98 million USD when the using land-based pipelines to transport captured $CO_2$ from the thermal power plant located in the south coast. And using marine-based offshore pipelines, it will cost about twice the amount. When the captured $CO_2$ is transported from the power plant in the west coast instead, the cost is expected to increase substantially due to the transportation distance to the storage site being more than double to that of the south coast power plant case.

• 산업경영시스템학회지
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• 제21권48호
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• pp.37-52
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• 1998

In many distribution systems important cost reductions and/or service improvements may be achieved by adopting an efficient inventory policy and proper selection of facilities. These efficiency improvements and service enhancements clearly require an integrated approach towards various logistical planning functions. The areas of inventory control and transportation planning need to be closely coordinated. The purpose of this paper is to construct an integrated model that can minimize the total cost of the transportation and inventory systems between multiple origin and destination points, where in origin point i has the supply of commodities and in destination point j requires the commodities. In this case, demands of the destination points are assumed random variables which have a known probability distribution. Using the lot-size reorder-point policy and the safety stock level that minimize total cost we find optimal distribution centers which transport the commodities to the destination points and suggest an optimal inventory policy to the selected distribution center. We also show if a demand greater than one unit will occur at a particular time, we describe the approximate optional replenishment policy from computational results of this lot-size reorder-point policy. This model is formulated as a 0-1 nonlinear integer programming problem. To solve the problem, this paper proposes heuristic computational procedures and a computer program with UNIX C language. In the usefulness review, we show the meaning and validity of the proposed model and exhibit the results of a comparison between our approach and the traditional approach, respectively.