• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.271-278
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• 2016

In the case of South Korea, steel girder bridge (steel box or H-steel) and PSC (Pre-Stressed Concrete) girder bridge are the representative upper structures of railroad and road bridges. These structures account for 75% of the total bridge constructions and 80% of the total construction cost. Since the form work for concreting bridge slab is difficult, various construction methods developed and applied. However, several problems in those methods did not solve partially, including cost increase by material loss and rise of labor costs, quality deterioration by unskilled workers, increased construction time by complicated method, reduced productivity, safety accident by high place work, difficult transportation by big member, and rise of maintenance cost by material characteristic. Alternative method is needed to solve problems of as-is methods. Therefore, the purpose of this study is development of the purlin hanging system form for the girder bridge slab and its economic analysis. Through the findings of this study, it was verified that the purlin hanging system form is possible 60% reduction in cost and 80% reduction in time as comparison with conventional method.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.139-145
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• 2015

Modular construction is combined with manufacturing production process and conventional construction industry technique. Considering characteristic of modular construction production process, manufacturing facilities require indirect costs for utilities, equipment, and overall maintenance, which can affect modular units pricing. However, current modular construction cost classification is inadvertent to reflect the manufacturing overhead costs, because it is generally added as a percentage to sum of labor, material and equipment as it called in single cost pool used. This process is easy to estimate the total construction cost at the project starting points, but it brings on misunderstanding of project profit estimations by "cross subsidization phenomenon". To prevent this situation, in this research aims to provide modular construction overhead cost handling process at the detailed indirect cost calculation for manufacturing stage using Activity-Based Costing as one of the powerful method for overhead costs estimation and allocation. Using this research results, modular construction cost estimators have more detailed cost information of modular units and prevent to misallocate indirect costs. Also, it can be utilized to aid the understanding of the company's profit structure.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.115-131
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• 2001

The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

• Tribology and Lubricants
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• v.12 no.1
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• pp.1-5
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• 1996

자성유체는 자연에서 추출한 것이 아니라 자화성(Magnetizability)과 유도성(Flowability)을 동시에 갖도록 합성한 특수액체이다. 자성유체는 1960년대 중반에 미국의 NASA에서 처음 개발된 이후로 윤활, 밀봉, 감쇄, 의료 등의 분야에서 응용연구가 많이 진행되었기 때문에 고도의 정밀도를 요하는 항공, 우주산업, 컴퓨터와 반도체 분야 등에서 실용화가 크게 진전되고 있다. 특수물질일 자성유체는 전기적으로 도체인 10nm 정도의 미세한 자기입자(Magnetic particles)에 코팅을 한 후, 이것을 물, 탄화수소, 플루오르카본, 에스터 등의 매개유체(Carrier Fluids)에 혼합시켜서 콜로이드 상태로 사용하게 된다. 자성유체는 미세한 자기입자들이 매개유체내에서 서로 충돌하면서 반발력을 발생시켜서 상호간에 늘 콜로이드 상태를 유지하고 있으며, 이 특수유체가 자기장의 영향을 받게 되면 점도가 증가하면서 특이한 성질을 갖게 된다. 상대 접촉 운동면에 경계마찰이나 혼합마찰을 하게 되면 윤활상태는 비교적 나쁘다. 이러한 마찰지역에 콜로이드상의 자성유체 윤활제를 공급하면 기존의 윤활제에 비하여 대단히 효과적으로 윤활을 할 수 있게 된다. 그러나 자성유체 윤활제가 마찰부위에 원활하게 공급하기 위해서는 미끄럼 마찰부에서 자기장을 잘 형성시킬 수 있는 도체이어야 하기 때문에 특별한 윤활 시스템 설계가 제시되어야 한다. 자성유체 윤활제는 합성으로 제조된 특수물질로 여러가지 장점을 갖고는 있으나 기존 윤활유와의 적합성, 마찰열, 밀봉압력 등의 조건에서 제한적으로 사용될 수 밖에 없으므로 항공, 우주 산업이나 석유 화학분야와 같이 특수 환경에서만 사용되고, 또한 기존의 광유계 윤활제에 비하여 대단히 고가하는 문제점을 갖고 있다. 그러나 윤활 마찰면의 다양화와 가혹한 사용조건은 자성유체 윤활제의 연구개발 필요성을 크게 증대시키고 있다.xed Effects Model)을 결정하고, 각각에 해당하는 통계모형을 구축하였다. 이 결과 (1) 업종 및 기업규모별로 그룹간에 유의한 특성이 발견되었으며, (2) R&D 및 광고투자는 기업의 시장성과를 설명하는 중요한 변수이나, (3) R&D 투자의 경우는 광고에 비해 불확실성이 존재하는 것으로 나타났고, (4) 수리모형에서 도출된 한계원리가 통계모형에서도 유효한 것으로 드러났다.등을 토대로 한 10대 산업을 육성하기 위하여 과학기술부는 기술수요조사를 바탕으로 49개 주요기술을 도출하여, 과학기술 일류 국가 실현, 국민소득 2만불 달성이라는 국가적 슬로건을 내걸고 “차세대 성장동력” 창출을 위한 범정부차원의 기획과 연구비의 집중투자를 추진하고 있다.달성하기 위해서는 종합류류 전산망의 시급한 구축과 함께 화물차의 적재율을 높이고 공차율을 낮출 수 있는 운송체계의 수립이 필요한 것으로 판단된다. 그라나 이러한 화물전용차선의 효과는 단기적인 치유책일 수밖에 없기 때문에 물류유통 시설의 확충을 위한 사회간접자본의 구축을 서둘러 시행하여야 할 것이다.으로 처리한 Machine oil, Phenthoate EC 및 Trichlorfon WP는 비교적 약효가 낮았다.>$^{\circ}$E/$\leq$30$^{\circ}$NW 단열군이 연구지역 내에서 지하수 유동성이 가장 높은 단열군으로 추정된다. 이러한 사실은 3개 시추공을 대상으로 실시한 시추공 내 물리검층과 정압주입시험에서도 확인된다.. It was resulted from increase of weight of single cocoon. "Manta"2.5ppm produced 22.2kg of cocoon. It is equal to 9% increase in index, as compared to that of control. In case

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.402-413
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• 2016

Marine oil spill accidents are occurring continuously due to the marine transportation of the oil. While building a preventive system for oil spill is uttermost necessary, we also need to have a systematic response system to handle the oil spills that inevitably occur. So far, studies have focused on the environmentally sensitive resources affected by oil spills. However, there is a need to conduct research to evaluate the damage to the socially and economically sensitive resources that make up the life of local residents. This study represents the process of building an analytical framework for the assessment of socioeconomic resources affected by marine oil spills. While it is important to provide a scheme for identification and indexation of socially and economically sensitive resources that is compatible with Korea's situations, using existing data for identifying socio-economically sensitive resources might also be meaningful. However, to allow accurate analysis for better evaluation, we need to select more applicable data among the various indicators. In this research, we have reviewed many existing case studies of sensitive resources, studies of the variables that have been used for indexing sensitive resources, and various factors considered in SIA (Social Impact Assessment). Based on the findings, we classify socio-economically sensitive resources into marine products acquisition, population, land usage, administrative area, and cultural heritage and tourist region.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.54-62
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• 2020

Watching the leakage accident of the Gumi Hube Global AHF(Anhydrous fluoric Acid), I experienced how much chemical accidents affect on our society. Since then, many studies have been conducted on chemical accident in many fields. The use department wanted to find improvement plans for the process system and apply them to the field. The safety field wanted to study improvement of safety through the analysis of damage effects and apply them to emergency response to reduce damage effects. In this study, Mechanical safe devices have been applied which can respond quickly to chemical accidents occurring during the charging operation to enhance the safety of the AFH ISO Tank(Anhydrous fluoric Acid International Organization for Standardization Tank). Investigation of similar tanks confirmed that other chlorine tanks with the same working procedure as AHF ISO Tank have a mechanical safety device, EFV(Excess Flow Valve). Applicability and performance for emergency shutdown when EFV is introduced in AHF ISO Tank can be verified by comparing and examining the accident situation of Hube Global Accident and the accident in Ulsan 2018. Comparing accident cases, expected performance and applicability, It is suggested that EFV, a mechanical safety device that can reduce damage from chemical accidents to the tank and handle accidents early, should be introduced to the tank.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1346-1356
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• 2011

Transportation has been playing important role in our society by providing for people, freight, and information. However, it cuts its own throat by causing car accidents, traffic congestion, and air pollution. The main cause of these problems is a noticeable growth in the number of vehicles. The easiest way to mitigate these problems is to build new road infrastructures unless resources such as time, money, and space are limited. Therefore, there is a need to manage the existing road infrastructures effectively and safely. In this paper, we propose a road reservation scheme that provides fast and safe response for emergency vehicles using ubiquitous sensor network. Our idea is to allow emergency vehicle to reserve a road on a freeway for arriving to the scene of the accident quickly and safely. We evaluate the performance by three reservation method (No, Hop, and Full) to show that emergency vehicles such as ambulances, fire trucks, or police cars can rapidly and safely reach their destination. Simulation results show that the average speed of road reservation is about 1.09 ~ 1.20 times faster than that of non-reservation at various flow rates. However, road reservation should consider the speed of the emergency vehicle and the road density of the emergency vehicle processing direction, as a result of Hop Reservation and Full Reservation performance comparison analysis. We confirm that road reservation can guarantee safe driving of emergency vehicles without reducing their speed and help to mitigate traffic congestion.

• Journal of Korea Port Economic Association
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• v.23 no.1
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• pp.163-193
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• 2007

Jeon-buk is well equipped for the growth of the logistics industry as it is the center of inland and marine traffic. However, it was not activated because of the infrastructure insufficiency. This paper surveyed the logistics industry facilities, interviewed people who are engaged in its business, researched into their business difficulties and the problem of the logistics industry of Jeon-buk. As a result of research, this paper makes an alternative plan for the development of the logistics industry of Jeon-buk area.

• Journal of Korean Society of Steel Construction
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• v.27 no.5
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• pp.471-481
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• 2015

Modular building is a prefabricated construction system for building where factory-produced pre-engineered modular units are delivered to site and assembled as substantial elements of a building. There are two basic kinds of modular structures. One is a load-bearing wall structure designed to transfer the load through longitudinal walls. The other is a frame structure composed of columns and beams. For frame structure, square hollow section is often used as a column member and channel as a beam member in modular unit. Lower and upper modules are fasten with bolts via a pre-installed access hole in the SHS column. However, the access holes can weaken the panel zone that would affect the behavior of beam to column connection. The 5 specimens of beam to column connections with parameters of access hole, column thickness and diaphragm were made and this paper describes the test results.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.55-63
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• 2015

Recently, terroristic threats using a radio controlled improvised explosive device (RCIED) that is remotely controlled and exploded have been increased around the world. In order to prevent the explosion of an RCIED, jamming techniques that interrupt an RCIED receiver can be used, so that the receiver can not demodulate the trigger code. Conventional jamming technique is a type of active barrage jamming that always emits the noise jamming signal for all the frequency band. However, it needs large power consumption and thus is limited in operation time for a vehicle. In order to overcome the shortage of the active barrage jamming, reactive jamming technique has drawn attention. In reactive jamming, all the frequency band is firstly scanned, and then if any trigger signal exists, one emits the jamming signal to the corresponding frequency band. Therefore, the reactive jamming is superior to the active barrage jamming in terms of power efficiency. However, a reactive jammer emits a jamming signal only after the trigger signal is intercepted, which means that the jamming signal may be late for interrupting an RCIED receiver. In this sense, it is needed to evaluate a delay in an RCIED receiver. To achieve this, we analyze the reaction time and present the simulation result for jamming performance of reactive jamming against an RCIED using mobile devices.