• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.313-317
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• 2017

With the continuous increase of energy demand, low-grade coal is regarded as one of new energy sources. However, due to the high water content, the utilization efficiency of low-grade coal is not good to be used in recent conversion plants. Therefore, it requires a drying process to lower the water content in low-grade coals. Although a variety of drying experiments were conducted, drying characteristics in accordance with the pressure change has not been progressed. In this study, the flash drying characteristics of low grade coal with high moisture content (21.5 wt%) were determined in a pressurized micro-riser. The effect of operation conditions such as pressure (1-40 bar), dryer temperature ($200-600^{\circ}C$), and tube length (2-6 m) on drying ratios were investigated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.9-18
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• 2011

The spalling phenomenon occurs in high-strength concrete when several factors such as sharp temperature increase, high water content, low water/cement ratio and local stress concentration in material combine in the concrete material. On the basis of the factors, the preventing methods from the spalling are known as reduction of temperature increase, preventing of concrete fragmentation and fast drying of internal moisture. In this study, the reduction of temperature increase was proposed as the most effective spalling-preventing method among the spalling-preventing methods. Engineered cementitious composite for fireproof and repair materials was developed in order to protect the new and existing RC structures form exterior deterioration factors such as fire, cloride ion, etc. This study was carried out to estimate the fire-resisting performance of high strength concrete slab or tunnel lining by repaired engineered cementitious composite (ECC) or fiber reinforcement cemetitious composite (FRCC) under fire temperature curve. and them we will descrike the result of HIDA tunnel in Japan.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.279.2-279.2
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• 2014

반도체 선폭이 20 nm급까지 감소함에 따라 기존에 수율에 문제를 끼치던 공정 외부 유입 입자뿐만 아니라, 공정 도중에 발생하는 수~수십 나노의 작은 입자도 수율에 악영향을 끼치게 되었다. 이에 따라 저압, 극청정 조건에서 진행되는 공정 중 발생하는 입자를 실시간으로 모니터링 할 수 있는 장비에 대한 수요가 발생하고 있다. Particle beam mass spectrometer (PBMS)는 이러한 요구사항을 만족할 수 있는 장비로 100 mtorr의 공정 조건에서 5 nm 이상의 입자의 직경별 수농도를 측정할 수 있는 장비이다. PBMS로 입자의 수농도를 측정하기 위해서는 PBMS 전단에서 입자를 중앙으로 집속할 필요가 있다. 공기역학렌즈는 PBMS 전단에서 입자를 집속시키기 위해 일반적으로 널리 사용되고 있는 장비로 여러 개의 오리피스로 이루어져 있다. 공기역학렌즈를 지나는 수송 유체와 입자는 이러한 연속 오리피스를 거치면서 팽창과 수축을 반복하며, 관성력의 차이로 인해 입자가 중앙으로 집속된다. 그러나 기존 공기역학렌즈는 고정된 직경의 오리피스를 사용하기 때문에 설계된 공정조건 이외에는 입자의 집속효율이 감소한다는 단점을 지닌다. 따라서 공정조건이 바뀔 경우 공기역학렌즈를 교체해야 되며, 진공이라는 환경하에서 이러한 교체는 많은 시간과 노력을 요구로 한다. 본 연구에서는 이러한 공기역학렌즈의 문제점을 해결하기 위해 다양한 공정조건에서 교체 없이 사용할 수 있는 새로운 형태의 공기역학렌즈인 조기래형 공기역학렌즈를 제안하였다. 각각의 오리피스가 중공의 직경을 변경할 수 있는 구조인 조리개의 형태로 설계되어 있어, 공정조건에 따라 중공의 직경을 변경함으로써 입자의 집속을 결정하는 요소인 Stokes number를 조절 할 수 있다. 이러한 조리개형 공기 역학 렌즈의 성능을 평가하기 위해 수치해석적인 방법을 이용하였다. 공기 역학 렌즈 전단의 압력을 0.1~10 torr까지 변화시켜가며 다양한 공정조건에서 오리피스의 직경만을 변경하여 입자 집속 가능 여부를 판단하였으며, 조리개 형태의 구조상 발생할 수 있는 leak로 인한 입자 집속 효율의 변화도 평가하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.399-408
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• 2006

Railroads have been developed as public transportation and made a great contribution to national economic growth. But after the mid-20th century, its qualities have been getting low because of focusing on the investment and development of cars and airplanes. Its role which is getting the excellent merits on the mass transportation, rapid transit, safety, state period, energy efficiency, and prevention of environmental pollution has been reconsidered. Elements of horizontal alignment are needed in the case where the existing railroad lines should be improved or moved. If its design drawing was lost or damaged, it is impossible to recover. It is not easy to repair for it as disasters. We must understand an existing railroad line to bring a function included a basic geography situation. In this study, we acquire, analyze, and process the digital images of the railroad and then reappear shape of three dimension. And we expect to be utilized to construct the facility information by extracting the alignment elements of existing railroad lines reversely.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.59-73
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• 2016

The demand for subsurface transport is increasing. The users and the operators of road tunnels are exposed to risks with different causes. One main cause, however, is the traffic situation in the event of accidents. The importance of a Quantified Risk Assessment is increasing to quantify the safety of road tunnels and to balance the requirements (capacity, reliability, availability, maintainability and safety) of various stakeholders. Although there are classical methods for risk assessments, such as ETA and FTA. These methods are used for relatively simple cases because it could not relevantly reflect the diversity and relationship of the parameters. Therefore, a quantitative risk assessment based on Bayesian Probabilistic Networks considering interdependence between the parameters of a complex underground system as a double deck tunnel is provided.

• Journal of Digital Convergence
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• v.14 no.2
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• pp.131-140
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• 2016

Logistics service is a prerequisite for efficient market economy and to support the purchase and consumption by promoting smooth transport goods between economic actors. Especially, logistics activities of the company are the source of essential business activities and competitiveness, which is responsible for the production and distribution of products and services to be delivered to consumers. Domestic logistics companies have to resolve challenges such as petty status and low productivity, inefficiencies in the logistics industry system, limit the growth of third party logistics market according to the growth as 2PL central logistics companies, and absence of global leader in logistics enterprises. This study examines the definition and development of third party logistics and analyzes the domestic third-party logistics market conditions. Based on the former analysis, this paper presented separately the activated measures of domestic third-party logistics by corporate side, the supply side, and the government's policy support.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.239-244
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• 2017

The demand for electric power is increasing every year. All facilities operating at power stations and all facilities used in transmitting high volumes of electric power are therefore expected to operate with a high degree of reliability. 6.6 kV XLPE 100 SQ 1C cables are used to deliver high levels of generated electric power. Depending on the method of manufacture, installation environment, and usage conditions, the deterioration processes of power cables start from the instant of operation. Cable junctions may break down in three years from the start of operation due to manufacturing or construction defects. We have invented the first device in Korea to monitor the status of live cables and installed these at Korea Western Power Co., Ltd.. We have set the criteria to determine deterioration status and specified the degree of deterioration at which one should replace the cables. In this paper, we present the effect of insulation layer and sheath on the insulation resistance status in cables.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.107-112
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• 2013

In the paper, velocity controller of switching module and temperature controller for the high-voltage static var compensator are proposed. Because of the continuous increase in demand for electric power, transmission and distribution facilities of power plant are required. There is a bottleneck problem of transportation routes according to new construction and expansion of power transmission facilities. Therefore there are researches to maximize the utilization of existing facilities and to increase transmission capacity without new construction. The previous static var compensator detects voltage of input circuit of power, switches the SCR directly and generates switching noise. The proposed method increases switching velocity and decreases noise using switching control based on the voltage between both sides of SCR. Also the proposed method enhance the stability using realtime temperature control for heating of the system from increase of switching velocity. We experiment the velocity and temperature control of the proposed high-voltage static var compensator in the real environment and verify the performance of the proposed system by applying in the real field.

• Convergence Security Journal
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• v.20 no.1
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• pp.15-24
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• 2020

Cyber terror and cyberwarfare are no longer virtual, but real, and as an actual security situation, it is necessary to have new understanding through expanding the concept of war to neutralize not only the other country's military command system, but also the country's main functions such as telecommunications, energy, finance, and transport systems, and it also needs to establish the future development strategy of cyber terror response at the national level. Through analysis of cyberwarfare trends in each country and current status of cyberwarfare in Korea, it will systematically explore the demand of new policy based on laws and systems, including the strategies of cyber security technology development, industry promotion, and manpower training and existing information protection policies. through this, it effectively manages a sustainable national crisis, and it suggests to establish a future strategy for the medium and long term cyber security that can effectively and actively respond to cyberwarfare.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.313-319
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• 2014

Additional train scheduling is often required to increase the capacity of transporting passengers or freight. In most previous studies on scheduling additional trains, operation time of the added train is designated first; and then the train operation feasibility is examined. However, it is often difficult to apply this approach to domestic trains because the density of the railroad network in Korea is high and various types of trains are in use. Moreover, for freight trains, it is even more challenging because the delay is accumulated due to lower priority whenever a freight train and a passenger train contend for a common segment of rail. In this paper, we address the additional train scheduling problem which entails finding a feasible schedule for an additional train having a fixed departure time or departure time windows. The problem is modeled as a mixed integer programming and a column generation technique is used to solve it.