• 대한교통학회지
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• 제27권2호
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• pp.199-206
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• 2009

교통시설 투자평가에 대한 경제성 분석과 관련하여 일반적인 예비타당성조사 지침 및 투자평가지침에서 적용하는 차량운행 비용 절감편익 중 유류비 산정 자료는 차량운행시 유류소모량과 주행속도와의 관계만을 고려하여 분석하고 있다. 신호로 인한 정지지체가 발생하지 않는 연속류의 경우 주행속도와 통행시간의 변화로 인한 절감편익에 대한 고려가 가능하나, 실제 신호교차로상에 신호제어로 인해 정지가 발생하는 단속류에 대해서는 정지지체시간감소 및 정지율 개선에 대한 고려가 없어 개선 효과분석의 현실반영이 어렵다. 따라서 기존 연구에 정지지체시간감소에 따른 절감편익을 보완하여 차량운행비산정 모형 관계식을 개발함으로써 신호교차로 특성을 반영한 편익을 분석 할 수 있는 기틀을 만드는 데 본 연구의 목적을 두었다. 공회전시 유류소모량 적용으로 정지지체시간를 고려한 차량운행비용을 재정립하였고, 서산시 가로축 2개에 대한 교통신호체계 최적화사업에 적용하여 기존 모형 적용시와 개발모형 적용시 경제적 편익에 대하여 분석하였다. 도로의 혼잡지역 증가로 교통체계관리의 중요성이 부각되는 가운데 신호연동체계 개선 및 혼잡개선 사업등의 효과분석에 있어 신호교차로 특성을 고려한 경제성 분석의 모형제시를 통해 지체도 개선을 반영한 좀 더 현실적 경제성분석에 도움을 줄 수 있을 것으로 기대한다.

• 대한조선학회논문집
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• 제58권5호
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• pp.294-302
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• 2021

In this study, the 3D printing technique called design for additive manufacturing (DfAM) that is widely used in various industries was applied to marine leisure ships of equipment. The DfAM for the stanchion for crew safety was applied to the equipment used in an actual recreational craft. As design constraints, the design alternatives were not to exceed the safety and weight of the existing stainless steel material, which were reviewed, and the production of a low-cost FFF-type 3D printing method that can be used even in small shipyards was considered. Until now, additive manufacturing has been used for manufacturing only prototypes owing to its limitations of high manufacturing cost and low strength; however, in this study, it was applied to the mass production process to replace existing products. Thus, a design was developed with low manufacturing cost, adequate performance maintenance, and increased design freedom, and the optimal design was derived via structural analysis comparisons for each design alternative. In addition, a life-cycle assessment based on the ISO 1404X was conducted to develop sustainable products. Through this study, the effectiveness of additive manufacturing was examined for future applications in the shipbuilding industry.

• 한국항해항만학회지
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• 제46권6호
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• pp.562-569
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• 2022

기존 운항선박에 적용되어 있는 알람 모니터링 기술은 온도, 압력 등의 데이터 항목을 AMS(Alarm Monitoring System)으로 관리하고 해당 센싱 데이터가 정상 수준 범위를 초과할 경우만 선원에게 알람을 제공한다. 또한 기존 선박의 정비는 PMS(Planned Maintenance System)를 따른다. 이는 장비로부터 측정된 센싱 데이터가 설정범위 이상으로 측정되어 이에 따른 알람을 통해 정비하거나, 대상 기기의 고장 유무에 관계없이 일정 시간 사용 후 해당 부품을 사전에 교체하는 방식으로 운영되고 있다. 하지만 선박 기관운영의 신뢰성과 운항 안전성을 확보하기 위해서는 실시간 상태 모니터링 데이터 기반의 사전적 진단 및 예측이 가능해야 한다. 그러기 위해서 실선 데이터를 종합적으로측정하여 데이터베이스화 하고 이를 선박의 보조기기와 배관의 상태기반 예지보전을 위한 상태 진단 모니터링 시스템을 구현하고자 한다. 특히 반응형 웹 기반으로 선박의 보조기기와 배관 상태 정보를 관리할 수 있도록 하였으며, 선내 개인용 컴퓨터(Personal Computer, PC)에서 보는 용도뿐만 아니라 스마트폰 등 다양한 모바일 기기의 접근 및 활용이 가능하도록 화면과 해상도에 맞춰 최적화된 상태 관리가 가능하도록 하여 업데이트 비용이 적게 들며, 관리 방법도 쉽다. 본 논문에서는 자율운항선박 핵심 기술인 상태기반정비(Condition Based Management, CBM) 기술력을 확보하기 위해 선박의 보조기기 중 펌프와 청정기, 그리고 배관 중 해수 및 스팀 배관의 상태 진단 모니터링을 통해 이상 현상을 파악하고, 이를 통해 융합 분석할 수 있도록 선박 보조기기 및 배관의 성능 진단 및 고장 예측에 활용하여 예방정비 의사결정을 지원하고자 한다.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.979-986
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• 2021

Online food delivery and food delivery apps have continued to grow exponentially in Malaysia. Fundamental aspects in entrepreneurship of the food and beverage industry, such as knowledge and attitudes towards online food delivery services being outsourced, have yet to be extensively recognized. The present study intends to explore this area of subject matter within the Malaysian context by using behavioral reasoning theory. The actual interview for this study took place in May 2020, and 14 interviews had been carried out. All interviews were audio-recorded with the consent from the respondents for reference purposes and subsequently transcribed verbatim. The transcripts were then checked against audio records. Content analysis was used to analyze the transcripts by focusing on n frequency counts and coding of themes. A qualitative method has been adopted by employing an interview to elicit the perspectives of entrepreneurs from Sarawak on the determinants and barriers in outsourcing online food delivery services. Results indicate that high potential in revenue, broad exposure to reach customers, convenience, and provision of job opportunities are the four factors that determine to outsource. In contrast, food quality maintenance, trustworthiness, high cost incurred, and consumer technology resistance are four factors that serve as barriers towards outsourcing third-party online delivery.

• 상하수도학회지
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• 제32권1호
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• pp.37-45
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• 2018

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.

• Tribology and Lubricants
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• 제37권2호
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• pp.48-53
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• 2021

Wind energy is considered as the most competitive energy source in terms of power generation cost and efficiency. The power train of the pitch drive for a wind turbine uses a 3-stage complex planetary gear system in being developed locally. A gear train of the pitch drive consists of an electric or hydraulic motor and a planetary decelerator, which optimizes the pitch angle of the blade for wind generators in response to the change in wind speed. However, it is prone to many problems, such as excessive repair costs in case of failure. Complex planetary gears are very important parts of a pitch drive system because of strength problem. When gears are designed for the power train of a pitch drive, it is necessary to analyze the fatigue strength of gears. While calculating the specifications of the complex planetary gears along with the bending and compressive stresses of the gears, it is necessary to analyze the fatigue strength of gears to obtain an optimal design of the complex planetary gears in terms of cost and reliability. In this study, the specifications of planetary gears are calculated using a self-developed gear design program. The actual gear bending and compressive stresses of the planetary gear system were analyzed using the Lewes and Hertz equation. Additionally, the calculated specifications of the complex planetary gears were verified by evaluating the results from the Stress - No. of cycles curves of gears.

• 대한토목학회논문집
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• 제32권6D호
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• pp.663-671
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• 2012

철도노선에 콘크리트궤도가 본격적으로 적용되고, 승차감 향상 및 고속화와 궤도유지보수비용 저감을 위해 장대레일의 수요가 급증하고 있다. 그러나 국내의 콘크리트궤도 현장 적용년수가 길지 않아 실제 현장에서 반복적인 열차하중을 받아 장대레일이 파단된 사례가 현재까지 없기 때문에 실제 현장 데이터를 이용하여 장대레일의 수명을 예측하고 교체주기를 산정하는 것은 어려움이 있다. 따라서 본 연구에서는 차량/궤도 상호작용해석을 통해 레일에서 발생하는 응력을 검토하여 그 해석결과 값에 대해 중회귀분석을 수행하여 운행속도와 표면요철에 따른 레일 휨응력 예측식을 도출하였다. 최종적으로 산정된 예측식을 이용하여 콘크리트궤도 장대레일의 피로수명을 예측하였다.

• 토지주택연구
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• 제2권2호
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• pp.101-109
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• 2011

Recently, the construction of U-City or of U-City service (U-service) in many kinds of urban development projects becomes the general trend. However, as the construction of U-city comes into the spotlight like the trend of the times, various service constructions are being indiscreetly implemented since it's processed focusing on local specialized projects or local landmark project by a local autonomous entity or an institute in charge being off the original purpose of the improvement of living quality of residents and the efficiency of urban management, which causes a number of problems on the process, maintenance, operation and management of those projects. Therefore, this study is to derive the standard pattern of U-service construction through the analysis of patterns and numbers of U-service and problems during the process of construction in domestic U-City construction case district, and is aimed to suggest the reasonable direction of service construction based on this. 11 projects areas in which data related to U-service are available among U-City construction project areas were selected for the subjects of this study, and it's standardized with 228 detailed unit services that were suggested by U-Eco City R&D and with 11 service domains that are regulated in "the Act of ubiquitous city construction etc.", and it is limited to services that were suggested in U-City case area of which design was completed by July, 2010 based on this. The actual state of various U-service construction is analyzed through case studies as well as reviews on the legal and theoretical concept and the method of pattern classification of U-service, the plan for the standardization (pattern classification) of U-service and the plan for the construction body of service and to share the costs are suggested as the plan to construct reasonable U-service based on this for the method and the procedure of this study For the method to construct U-service, the plan to classify the pattern of U-service into the basic service and additional service is suggested, and whether it has the publicity, whether urban infrastructure is included, whether utilities are included, the body of realization, the recipients, the urgency, the importance and the spreading, etc. are suggested for the index to determine the pattern of service. The method to get the executor of a project to construct the basic service, the method to get the executor of a project to construct the most basic service among the group classification of service and to get a private entity and a local autonomous entity to perform additional service in the future, and the method to construct the whole service and to distribute the construction costs were suggested, and the first one that determines the body of construction after dividing U-service into the basic service and the additional service was evaluated to be the most reasonable one. And the plan to solve the problem that the excessive construction costs of U-service are shifted onto the executor of a project through benefit principle, balanced distribution principle and consultation and mediation between the interested parties was suggested for the criteria to share the costs.