• Journal of Construction Engineering and Project Management
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• 제5권1호
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• pp.11-19
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• 2015

This paper presents optimized artificial neural networks (ANNs) claims prediction and decision awareness framework that guides owner organizations in their pre-bid construction project decisions to minimize claims. The framework is composed of two genetic optimization ANNs models: a Claims Impact Prediction Model (CIPM), and a Decision Awareness Model (DAM). The CIPM is composed of three separate ANNs that predict the cost and time impacts of the possible claims that may arise in a project. The models also predict the expected types of relationship between the owner and the contractor based on their behavioral and technical decisions during the bidding phase of the project. The framework is implemented using actual data from international projects in the Middle East and Egypt (projects owned by either public or private local organizations who hired international prime contractors to deliver the projects). Literature review, interviews with pertinent experts in the Middle East, and lessons learned from several international construction projects in Egypt determined the input decision variables of the CIPM. The ANNs training, which has been implemented in a spreadsheet environment, was optimized using genetic algorithm (GA). Different weights were assigned as variables to the different layers of each ANN and the total square error was used as the objective function to be minimized. Data was collected from thirty-two international construction projects in order to train and test the ANNs of the CIPM, which predicted cost overruns, schedule delays, and relationships between contracting parties. A genetic optimization backward analysis technique was then applied to develop the Decision Awareness Model (DAM). The DAM combined the three artificial neural networks of the CIPM to assist project owners in setting optimum values for their behavioral and technical decision variables. It implements an intelligent user-friendly input interface which helps project owners in visualizing the impact of their decisions on the project's total cost, original duration, and expected owner-contractor relationship. The framework presents a unique and transparent hybrid genetic algorithm-ANNs training and testing method. It has been implemented in a spreadsheet environment using MS Excel$^{(R)}$ and EVOLVERTM V.5.5. It provides projects' owners of a decision-support tool that raises their awareness regarding their pre-bid decisions for a construction project.

• 전기학회논문지
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• 제67권5호
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• pp.601-610
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• 2018

The purpose of this paper is to establish a new optimum Generator Maintenance Scheduling(GMS) considering renewable energy generator. In this paper, the total renewable energy generation is estimated using hourly capacity factor of renewable energy generator. The GMS was optimized with the objective function of maximizing the minimum reserve rate, minimizing the probabilistic production cost, minimizing the loss of load expectation, and minimizing $CO_2$ emissions. In the case study of this paper, GMS considering renewable energy and GMS not considering renewable energy are shown by each objective function. And it shows scenarios of the reliability, the environmental and economical factors when two nuclear power plants inputted and ten coal thermal power plants shut downed respectively.

• 수산해양기술연구
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• 제51권2호
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• pp.163-170
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• 2015

Recently LED fish-attracting lamps have been more widely used in fisheries as low-cost and high-efficiency fishing gear, and development of long-life high-efficiency lamps is required through the design of LED packages to optimize heat resistance. This study developed an improved LED fish-attracting lamp with excellent heat performance, which was verified using a numerical model. Heat-resistance design factors such as the heat-radiation fin shape, PCB type, and LED chip count were investigated and optimized. Comparison with a commercial 180-W LED fishing lamp showed that the increase in initial temperature was 40% higher than that of the surrounding LED chip because of design errors in contact thermal resistance. The 250-W LED lamp developed in this study has a characteristic with thermal rising in linearly stable according to the heat source. In addition, luminance efficiency was improved by 20-65% by using flow-visualization simulation. A decrease of 45% in total power consumption with a fuel-cost reduction of over 55% can be expected when using these optimized heat release design factors.

• 적정기술학회지
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• 제5권1호
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• pp.8-17
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• 2019

Solar pumps, for water lift systems, is becoming popular in rural areas for supplying drinking water in dry seasons when its need is elevated. The development in technology has also made solar pumps readily available and cheap which has increased its demands. So, for scattered settlements having a limited budget for operation and maintenance costs, solar pump is preferred over grid connected electrical pumping systems. This primary objective of the study was to design a solar photovoltaic pumping drinking water supply system for a small health post which is about 45 km east from Kathmandu, the capital city of Nepal. The study also compared and verified the final design with the system's existing design prepared by a development agency. The water source for this study was a confined aquifer 115m below the surface. The water demand was calculated to be 11m³ per day. A 1500 kPa submersible pump attached to a motor was selected and installed. Along with that twelve solar panels, reservoir, transmission main and distribution main was designed. The outcomes conclude solar photovoltaic pumping water supply systems to be cost-effective with an estimated cost of only USD 0.84 million per MLD. Solar pumps require low maintenance and operation costs and its repairs can quickly be done by the local people. The study also shows that solar technology produces no sound, needs no fuel making it environmentally friendly.

• Neonatal Medicine
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• 제17권1호
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• pp.13-20
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• 2010

목 적: NICU에 입원하는 환아들은 고위험 신생아나 미숙아이기 때문에 적절한 입원기간을 거쳐 퇴원하게 되어도, 아기 자체의 미숙성이나 질병의 후유증으로 인해 퇴원 후에 재입원을 하게 되는 경우가 많다. 이 재입원의 빈도와 의료비용을 알아보고자 하였다. 방 법:전국에 분포한 7개 대학병원의 NICU를 대상으로 2005년 7월부터 2006년 6월까지 1년 간 입원하였다가 생존하여 퇴원한 총 3,451명을 대상으로 퇴원 후 1년간의 재입원에 대한 재입원의 빈도(비율, 횟수), 이유(병명), 비용(1회 재입원 시 평균 비용, 1회 재입원 시 1인당 입원비의 분포, 1회 재입원 시, 전체 재입원 비용중 급여와 비급여의 비율, 1인당 비급여액의 분포, 2회 이상 재입원 환자에서 1인당 재입원 횟수에 따른 1년간 평균 총 입원비용, 2회 이상 재입원 환자에서 1인당 재입원 횟수에 따른 1년간 총 입원비의 분포 등을 살펴보았다. 결 과:퇴원 후 1년간 재입원을 한 아이는 14.8%였고, 다회 입원의 연인원으로 계산 시, 21.7% 이었다. 재입원의 원인 병명을 빈도 별로 살펴보면, 폐렴(15.8%), 세기관지염(14.5%), 위장염(10.4%), 요로감염증(6.3%), 패혈증(의증 포함) (6.3%) 등의 감염질환이 상위였으며, 선천성 기형에 의해 수술적 치료, 미숙아나 질병 신생아와 관련된 후유증 등이 많은 빈도를 차지하고 있었다. 1회 재입원 시 평균 비용은 총 1,652천원이고, 이 중 보험급여액은 1,170천원, 비급여액은 472천원이다. 보험급여와 비급여의 비율은 71.4:28.6%이었다. 결 론: NICU에서 받았던 치료나 질병에 관련되는 병으로 퇴원 후 1년에 재입원하게 되는 경우가 약 20% 정도로 이러한 NICU 퇴원 환아들에 대해서는 퇴원 후 추적관리가 매우 중요하며, 퇴원 후 관리에 관심과 주의가 필요하다. 이에 따른 총 입원비용 및 비급여의 본인 부담금이 상당 부분 있기에, NICU 퇴원 후에도 치료를 지속적으로 필요하여 재입원 시에 의료비용도 본인부담의 면제조처가 필요함을 강력히 시사하고 있었다.

• 플랜트 저널
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• 제11권2호
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• pp.45-51
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• 2015

손실비용을 고려하여 발전소 효율에 큰 영향을 미치는 복수기의 운전 관리 방안을 연구하였다. 2013년 S발전소의 해수온도는 복수기 압력과 뚜렷한 상관관계를 보였으며, 해수온도가 변화함에 따라 복수기 압력은 설계 압력 38.1 mmHg 보다 -1.7~+20 mmHg의 차이로 운전되었다. 제작사에서 제시한 열소비율 보정곡선을 통해 복수기 압력 1 mmHg 증가시 1,2호기 0.0201%, 3,4호기 0.0155%의 효율 손실과 1,2호기 12,830 원/h, 3,4호기 9,832 원/h의 시간당 손실비용이 발생함을 알 수 있었다. 또한 계절별 대응운전, 설비 노후화, 예방정비 시점에 따른 손실비용의 차이를 확인하고 월별 관리범위를 설정하였다. 이를 통해 운전 관리범위 준수, 손실비용을 고려한 정비 계획 수립으로 최소 2.5억원/년(1호기, 40일 정비)의 관리적 손실을 줄일 수 있을 것으로 판단된다.

• 해양환경안전학회지
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• 제18권4호
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• pp.345-351
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• 2012

우리나라의 주요 교역권은 아시아, 미주, 유럽 교역권으로 나눌 수 있다. 일반적으로 대량의 화물운송은 해상운송이 주를 이루지만 다른 지역과 다르게 유럽 교역권은 철도 운송이 가능하다. 또한, 중국의 성장으로 동북아 물류 중심지로서의 경쟁력이 약화된 우리나라는 지금의 경쟁구조와는 다른 방안인 철도운송에 주목할 필요가 있다. 이러한 배경 하에 본 연구에서는 한반도 종단 철도(TKR)와 시베리아 횡단철도(TSR)를 이용한 유럽 지역과의 운송 경로를 비교하여 경제성 분석에 주안점을 두었다. 분석의 요소로는 운송거리, 운송기간, 운송비, 추가비용을 중심으로 사용하였으며 분석 결과 6가지의 운송경로 중에서 TKR과 연계한 TSR(Route 1)이 경제적이라는 분석 결과가 나왔다. 따라서 향후 러시아 푸틴정부의 극동발전 전략에 대비하여 우리나라는 TKR과 TSR의 철도운송을 활용하는 것이 국가 경쟁력을 높일 수 있는 방안이 될 것이다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.211-216
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• 2006

Within the frame of the MERCOSUR (South Common Market), one of the most important goals to achieve by its member states is a better cost effective international cargo transportation system. For this purpose the project of developing a commercial waterway linking the east region of Uruguay with the south of Brazil has been under study for a number of years now. Because of the high costs involved on the development of such waterway, the project has been indefinitely delayed. It is our intention to show an alternative way to reduce the present obstacles by using a budget oriented approach in order to determine the vessel best suited to use on the proposed waterway. So far, every study related to the project has been focused on the amount of work needed to modify the environment in order to accommodate the hardware already available in the region. The conclusions show that the cost of opening and maintaining the required navigation channel is high enough to discourage investment; the added responsibility to take care of any environmental damage incurred during the building and/or operation of the waterway makes searching for a less costly and hazardous option an interesting challenge. The proposed terminal on the Cebollat? River would be located at the heart of the Uruguayan rice growing region. Uruguay exports 90% of its rice production, being Brazil its biggest buyer. Wood chips and clinker are the other types of cargo considered to use the proposed waterway in route to either Brazil or to overseas destinations through the deep water port of Rio Grande. Through the analysis of local data by a Geographical Information System, international regulations regarding inland waterways and shallow draught vessel characteristics, we seek to propose a cost efficient alternative to apply on this particular scenario.

• Geomechanics and Engineering
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• 제18권5호
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• pp.535-543
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• 2019

Building on/with expansive soils with no treatment brings complications. Compacted expansive soils specifically fall short in satisfying the minimum requirements for transport embankment infrastructures, requiring the adoption of hauled virgin mineral aggregates or a sustainable alternative. Use of hauled aggregates comes at a high carbon and economical cost. On average, every 9m high embankment built with quarried/hauled soils cost $12600MJ.m^{-2}$ Embodied Energy (EE). A prospect of using mixed cutting-arising expansive soils with industrial/domestic wastes can reduce the carbon cost and ease the pressure on landfills. The widespread use of recycled materials has been extensively limited due to concerns over their long-term performance, generally low shear strength and stiffness. In this contribution, hydromechanical properties of a waste tyre sand-sized rubber (a mixture of polybutadiene, polyisoprene, elastomers, and styrene-butadiene) and expansive silt is studied, allowing the short- and long-term behaviour of optimum compacted composites to be better established. The inclusion of tyre shred substantially decreased the swelling potential/pressure and modestly lowered the compression index. Silt-Tyre powder replacement lowered the bulk density, allowing construction of lighter reinforced earth structures. The shear strength and stiffness decreased on addition of tyre powder, yet the contribution of matric suction to the shear strength remained constant for tyre shred contents up to 20%. Reinforced soils adopted a ductile post-peak plastic behaviour with enhanced failure strain, offering the opportunity to build more flexible subgrades as recommended for expansive soils. Residual water content and tyre shred content are directly correlated; tyre-reinforced silt showed a greater capacity of water storage (than natural silts) and hence a sustainable solution to waterlogging and surficial flooding particularly in urban settings. Crushed fine tyre shred mixed with expansive silts/sands at 15 to 20 wt% appear to offer the maximum reduction in swelling-shrinking properties at minimum cracking, strength loss and enhanced compressibility expenses.

• Clinical Nutrition Research
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• 제13권2호
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• pp.108-120
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• 2024

The study aimed to investigate the basic data to derive plans for snack provision to improve the nutritional status of older adults living in long-term care facilities (LFs) or long-term care hospitals (LHs). The 252 respondents (118 from LHs and 134 from LFs) were included in the study. The questionnaire of nationwide cross-sectional survey was developed by the authors and registered dietitians. The written questionnaire was sent to the food service managers across 800 LFs or LHs. The online survey was introduced using the online platform and network site for dietitians. More than 70% of live-in and non-live-in LFs provided snacks, which were mainly provided one to two times a day. Most institutions provided fruits one to three times a week. The main considerations when providing fruit were in the order of residents' preference, cost, and ease of consumption. The reasons for not serving fruit included cost and differences in the residents' eating and mastication abilities. Most institutions also provided dairy products at a frequency of one to three times a week. The reasons for not serving dairy products included cost and the lack of awareness of the need to provide them. To improve the quality of life and the offer benefits of fruits and dairy products to older people, efforts are needed to propose a plan to expand the provision of snacks in appropriate quantities and varieties.