• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.3
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• pp.11-18
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• 2013

Small and medium-size buildings employ a multi-distributed individual air-conditioning system utilizing package air conditioners instead of centralized cooling systems, which can allow easier building management and maintenance along with a diversification of facility use. Inverter driven system heat pumps have been developed to achieve not only easy distribution control allowing free combination of indoor units with different models and different capacities, but also wide applications to an intelligent air conditioning. In this study, the transient performance of a system heat pump was analysed with the variation of compressor speed and EEV openings. The superheat was selected as a control parameter of the system, because the variation of it was consistent with each indoor unit capacity.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.250-257
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• 2000

The speed-up of conventional trains is considered as one of the efficient methods to relieve traffic jam and to increase the capacity of transportation. In this study, we measured and analyzed the ride comfort of a push-pull Saemaeul Train with speed-up of 5km/h in curves and 10km/h on straight tracks as compared with present operation speed of the push-pull Saemaeul Trains. Four main lines-Honam, Kyungboo, Janghang, Kyungjeon- were chosen as representative lines for speed-up feasibility study. The increase of mean ride comfort index in case of speed-up is 0.5-2㏈. The mean ride comfort index of vertical direction in case of speed-up is 107-110㏈ for Honam line, 104-112㏈ for Kyungboo line, 108-112㏈ for Janghang line and 105-108㏈ for Kyungjeon line, which are rather high as compared with German trains of similar grade with maximum vehicle speed of 160km/h.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.271-281
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• 2000

A number of variables and environment are concerned for the basic design of train. The design of train ran be optimized by the ruining simulation. And using the simulation result the consuming energy, regenerating power, adhesion coefficient, train traction control capacity are respectable. Considering these variables and for more information operating time, operating period, standard velocity and limit speed, the all factors of train are optimized. The light-tail tram is mainly divided into linear motor train, road surface train, iron wheel train and rubber tire train, and the most profitable one for adhesion coefficient is rubber tire train and the train will be designed.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.550-555
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• 2005

In this research, safety requirements for guard rail, buffer stop, car stop scotch block, protection device, fire protection facilities, safety siding, escape facilities and inundation protection facilities are studied to establish a standard. First, various kinds of guard rails and their construction methods are investigated. Researches on the level difference of main track and guard rail, joint, length, and fastening force of guard rail are done. Second, the classification of buffer stop and car stop scotch block and its characteristics are examined, and the impact force, speed limit and capacity of buffer stop are summarized. Details of protection device, fire protection facilities, safety siding, escape facilities and inundation protection facilities are also investigated. From this fundamental research results, basic data on the safety facilities of railroad system are established.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.1093-1096
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• 2005

As the opening of Korea Railroad Express on April 1, 2004, it has extended the transportation capacity of railroad, and decreased the time and moving cost. Railroad Express is industry composed of transportation, advanced technology, and grand project for synthetic plan. Hence, here now, as the anniversary of Railroad Express, we should analyze the overall effect of Korean Economy by KTX. relationship with other industry, social and cultural change. That is the key point what is the change during the year and how we catch the chance to develope the Korea Railroad for the national economy. The KTX has overcome the speed which the traditional railroad not been. But the Express has a weakness in searching of customer or goods. KTX is helped by electronics and telecommunications. so we need to find new industry in relation to KTX. And we should have open mind and vision for international railroad.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1845-1854
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• 2007

기존의 철도용량의 개념은 하루동안 최대한 통과시킬 수 있는 최대 열차 횟수를 기본으로 하여왔다. 그러나 이러한 단순한 최대횟수는 그 사용상의 여러 가지 제한사항을 가지고 있다. 최대열차 운행횟수는 열차의 속도, 신뢰성등과 같이 고려하여야 하며, 이러한 고려는 자연스럽게 서비스수준과 같은 과거철도에서는 구체적으로 고려하지 않던 새로운 용량에 대한 접근을 요구하게 된다. 2004년에 세계철도연맹(UIC)에서 제안한 철도용량 산정절차는 이러한 측면에서 많은 점을 시사하고 있다. 새로운 절차의 한국의 지역간 철도에의 적용가능성을 검토해 본다. 본 연구에서는 2006년 11월 새로 개편된 경부선, 호남선의 열차시간표를 이용하여, 문제가 되고 있는 서울역${\sim}$시흥역 구간에 대해 UIC에서 새롭게 제시한 선로용량의 개념을 OpenTrack을 이용한 시뮬레이션을 통해 적용해보고, 이에 따라 선로 용량 산정시 적용할 수 있는 MOE를 찾아내 서비스수준(LOS)을 결정할 수 있는 방안을 제시해보고자 한다.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.836-845
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• 2007

In DC 1500V electric traction substations, diode rectifiers are commonly used to supply stable DC power with electric train sets. However, it operates in the first quadrant of the voltage-current plane and thus needs regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1481-1498
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• 2007

As railroad industry face the new Renaissance era, effective and efficient maintenance methods for rolling stock operation are required with advanced railroad technology. All kinds of railroad systems such as high speed long distance train, metropolitan mass transit and light rail require systematic maintenance technology in order to maintain the safe railroad operation. Simulation models for detailed operations of the sample maintenance center are developed. In this study, standard maintenance procedures, layout, equipments and number of workers of Siheung Metropolitan Railroad Maintenance Rolling Stock Depot are considered. The proposed simulation models are developed using simulation package ARENA. Three simulation analysis using the developed simulation model are done. First, the bottleneck operation is identified. Second, the relationship between maintenance center size, number of workers and cycle time is analyzed. Lastly, the scheduling performances between PERT/CPM and Critical Chain Project Management(CCPM) are compared.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.404-411
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• 2007

Reinforced roadbeds are valued from the point of view of maintenance as well as enhanced mechanical capacity. They support more train load and less transmit to the sub-layers than general roadbeds. Also, the lateral sloping surface of the reinforced roadbed and its low permeability, achieved by the controlled compaction, increase drainage capability and prevent the softening of sub-layers. In the study, a series of cross-hole tests was performed to observe the temporal changes in the stiffness of reinforced roadbeds, if any, due to the cyclic loading of trains and alternating rainy and frozen seasons at Pyeong-taek experimental site. The three types of reinforced roadbed materials are slag, crushed stones, and soils, and the thickness of all the reinforced roadbeds is 0.8m. The stiffness of the slag and soil reinforced roadbeds was not changed or slightly decreased. The stiffness of the crushed stone was somewhat increased and is inferred to being densified close to surface.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1802-1806
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• 2007

The most important factor is the roadbed bearing capacity at concrete track construction. Particularly, in case of rehabilitation, it is essential to secure the uniform roadbed stiffness to prevent the irregular settlement. In this study, reinforced effect of the geotextiles is investigated which is applied to concrete track rehabilitation. The geotextiles is installed two or three layers as the condition of the ground and structure. The reinforced effect of geotextiles is confirmed by the strain gage attached on the geotextiles surface.