• Journal of the Korean GEO-environmental Society
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• v.19 no.8
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• pp.11-17
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• 2018

Recently, road subsidence has been increasing in urban areas, threatening the safety of citizens. In the lower part of the road, various road facilities such as water supply and drainage pipelines and telecommunication facilities are buried, and the deterioration of the facilities causes the road subsidence. Especially, in the case of old sewer which are attracting attention as a main cause of ground subsidence, the risk of subsidence is calculated indirectly through CCTV exploration. Currently, we are finding cavity through GPR exploration. However, it is difficult to find the sewer back cavity because it is explored from the surface of the road. Thus, the nondestructive cavity exploration techniques was investigated in this study and we confirmed the applicability through experiments on the test-bed. In this study a new quantitative method is proposed to detect the cavity around sewer.

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.46-52
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• 2009

Hydrogen can extend the lean misfire limit to a large extent when it is mixed with conventional fuels for an internal combustion engine. This study is about fuel reforming to produce hydrogen enriched gas as a fuel for engine. Especially gasoline, which consists of numerous hydrocarbon fuels, considered as source of reformed gas. Various hydrocarbons, including commercial fuel were reformed and potentialities of reformed gas on vehicles were accessed. The reforming efficiency and hydrogen yield were observed. Maximum hydrogen yield were found with different gas hourly space velocity(GHSV) and O2/C ratio of reforming conditions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.99-111
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• 2018

Service areas in expressways are very important facilities in terms of efficient expressway operation and the convenience of users. It needs a traffic management strategy to inform drivers in advance about congestion in service areas so as to distribute users of service areas. But due to the lack of sensors and data on numbers of people in the service areas, congestion in service areas had not been measured and managed appropriately. In this study, a congestion index for service areas was developed using telecommunication floating population big data. Two alternative indices (i.e., density of service areas and floating population V/c of service areas) were developed. Finally, the floating population V/c of service areas was selected as a congestion index for service areas for reasons of the ease of understanding and comparison.

• Spatial Information Research
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• v.4 no.2
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• pp.121-130
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• 1996

Current management endeavors towards the urban residential environment lack in specific evaluation criteria and relevant strategies. This study attempts to systematically evaluate the quality of the residential environment and to zone areas that need improvement. In the case of the Changshin -dong area, three steps were performed in GIS analyses. First, the quality of residential en¬vironment was evaluated in terms of four environmental objectives-- i.e. safety, health, convenience, and amenity. Second, for the areas that do not satisfy any of the four requirements above, zonig was conducted in terms of housing quality, infrastructure, and housing density. Finally, relevant strategies for improvement were assigned to those areas. The approach presents a shift from a current method that manily relys on experts' intuition or biased judgement, to a more systematic and logical one. Such an approach is expected to be useful for establishing other urban developmental strategies.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.191-198
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• 2002

This study was conducted to determine changes in internal temperature and chemical composition during the composting of broiler litter(BL) and to evaluate the feasibility of use of a small-scale pelletizer for the pelleting of composted BL. BL was composted for 4 weeks in an wooden cell with a size of 1 m length $\times$ 1 m width $\times$ 1.2 m height. Internal temperature reached to peak(68$^{\circ}C$) at the fourth day and thereafter gradually reduced. Among chemical components in BL, composting reduced organic matter content and increased dry matter and indigestible protein(ADF-CP) contents. When BL was pelleted using an economical small-scale pelletizer, the proper die diameter was 8~18 mm and the proper moisture content of composted BL was 20~25%. Beyond these proper conditions, addition of heat and pressure or pellet aids may be necessary. Pelleting of BL resulted in nearly threefold increase of bulk density, significant moisture evaporation, and little change in chemical components except for increased indigestible protein. In conclusion, BL may be converted into a feed with low to medium nutrition by the composting and pelleting process.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.159-166
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• 2004

The capacity concept presented in the Highway Capacity Manual is for steady-state traffic flow assuming that there is no restriction in downstream flowing, which is traditionally used for planning, design, and operational analyses. In the congested traffic condition, the control objective should be to keep the congested regime from growing and to recover the normal traffic condition as soon as possible. In this control case, it is important to predict the spatial-temporal pattern of congestion evolution or dissipation and to estimate the throughput reduction according to the spatial-temporal pattern. In this context, the new concept of dynamic capacity for managing congested traffic is developed in terms of spatial-temporal evolution of downstream traffic congestion and in view of the 'input' concept assuming that flow is restricted by downstream condition rather than the 'output' concept assuming that there is no restriction in downstream flowing (e.g. the mean queue discharge flow rate). This new capacity is defined as the Maximum Sustainable Throughput that is determined based on the spatial-temporal evolution pattern of downstream congestion. And the spatial-temporal evolution pattern is estimated using the Newell's simplified q-k model.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.82-88
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• 2012

A VANET (Vehicular Ad Hoc Network), a subclass of MANET (Mobile Ad Hoc Network), is an ad hoc network using wireless communication between vehicles without fixed infrastructure such as base station. VANET suffers a frequent link breakage and network topology change because of the rapid movement of vehicles and the density change of vehicles. From these characteristics of VANET, geographical routing protocols such as GPSR (Greedy Perimeter Stateless Routing) using only the information of neighbor nodes are more suitable rather than AODV and DSR that are used in existing MANETs. However, GPSR may have a transmission delay and packet loss by frequent link disconnection and continual local maxima under the low vehicle density conditions. Therefore, in this paper, we propose a DTVR (Delay Tolerant Vehicular Routing) algorithm that perform a DTN-based routing scheme if there is no 2-hop neighbor nodes for efficient routing under the low vehicle densities in VANETs. Simulation results using ns-2 reveal that the proposed DTVR protocol performs much better performance than the existing routing protocols.

• Journal of the Korean Institute of Gas
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• v.13 no.3
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• pp.15-21
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• 2009

Gas hydrate is an ice-like crystalline compound that forms at low temperature and high pressure conditions. It consists of gas molecules surrounded by cages of water molecules. Although hydrate formation was initially found to pose serious flow-assurance problems in the gas pipelines or facilities, gas hydrates have much potential for application in a wide variety of areas, such as natural gas storage and transportation. Its very high gas-to-solid ratio and remarkably stable characteristics makes it an attractive candidate for such use. However, it needs to be researched further since it has a slow and complex formation process and a high production cost. In this study, formation experiments have been carried out to investigate the effects of pressure, temperature, water-to-storage volume ratio, SDS concentration, heat transfer and stirring. The results are presented to clarify the relationship between the formation process and each factor, which consequently will help find the most efficient production method.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.291-291
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• 2009

한국원자력연구원의 파이로 실험 시설인 ACPF (ACP Facility)에는 공학규모 전해환원 반응기가 설치되어 공정 대용량화를 위한 연구가 수행되고 있다 본 연구에서는 전해환원 공정의 Scale-up을 위해 기존 반응기를 개선하여 전해환원 실험을 수행한 결과를 담고 있다. 장치의 대형화 빛 원격운전성 향상을 위해 기존의 전해환원 반응기의 상부 플랜지는 보다 간단하게 정리되었으며 염 이송에 의한 고온 조건 노출 시간을 줄임과 동시에 염 재사용을 목적으로 상부 플랜지는 이중으로 설계되었다. 따라서, 반응 종료후 전극이 설치된 상부 플랜지를 들어 올림으로서 반응기를 불활성 분위기로 유지하는 동시에 전해환원 금속전환체를 회수 할 수 있도록 반응기가 제작되었다. 또한, 새로운 반응기는 용융염 내의 강제 유동을 위해 아르곤 버블링이 가능하도록 설계 제작되었다. 새로 제작 설치된 전해환원 반응기를 사용하여 산화물 분말을 혼합하여 준비한 모의 사용후핵연료를 사용하여 전해환원 실험을 수행하였다. 그 결과, 산화물이 충진된 음극의 전영역에서 고루 96% 이상의 높은 금속전환율을 얻었으며 시간에 따라 선택된 FP들의 용융염 내 거동을 측정하였다. 실리더 형태의 음극에서 Cs, Sr 등의 원소들이 용융염으로 시간에 따라 용출되는 것을 확인하였으며 동시에 반응기 재질인 Fe 등도 일부 용융염에서 검출되었다. 아르곤 버블링에 의한 강제 유동은 전압 및 전류 거동에는 큰 영향을 미치지 못하였으나 염의 휘발량을 증가시켜 영조성올 변화시키는 것으로 측정되었다. ACPF의 전해환원 실험결과를 바탕으로 반응기를 상부 기체상과 하부 액체상으로 나누어 전산모사를 수행하였다 상부 기체상은 유입되는 아르곤 기체와 발생되는 산소기체의 흐름을 모사하는 결과를 얻었으며 온도 및 산소의 분압을 계산하였다. 하부 액체상에서는 전기장을 모사하여 전류 밀도 등을 3차원으로 모사하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2374-2381
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• 2012

The aims of this study are to verify the effecting factors in evacuation behavior under the corridor and stair width variation in evacuation experiments at university education facilities. To achieve these purposes, the present conditions of university education facilities were analyzed, and the evacuation experiment settings were established under different width of corridor and stairs. After the experiments, we asked the effecting variables to the evacuation behaviors under the variation of corridor, stair width and density of evacuee. The results of this study are as follows ; First, we found 3 main factors which affecting the evacuation behaviors ; environmental factors on building conditions, psychological factors on evacuee's characteristics and personal factors on evacuee's physical conditions. Second, the environmental factors such as the location of stairs for evacuation, recognition of wayfinding in fire condition are mainly affects the evacuation behaviors, but evacuee behaviors have little relations with fire extinguishing facilities and personality.