• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.27-30
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• 2001

Flow and transport at fracture intersections, and their effects on network scale transport, are investigated in three-dimensional random fracture networks. Fracture intersection mixing rules complete mixing and streamline routing are defined in terms of fluxes normal to the intersection line between two fractures. By analyzing flow statistics and particle transfer probabilities distributed along fracture intersections, it is shown that for various network structures with power law size distributions of fractures, the choice of intersection mixing rule makes comparatively little difference in the overall simulated solute migration patterns. The occurrence and effects of local flows around an intersection (local flow cells) are emphasized. Transport simulations at fracture intersections indicate that local flow circulations can arise from variability within the hydraulic head distribution along intersections, and from the internal no flow condition along fracture boundaries. These local flow cells act as an effective mechanism to enhance the nondiffusive breakthrough tailing often observed in discrete fracture networks. It is shown that such non-Fickian (anomalous) solute transport can be accounted for by considering only advective transport, in the framework of a continuous time random walk model. To clarify the effect of forest environmental changes (forest type difference and clearcut) on water storage capacity in soil and stream flow, watershed had been investigated.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.148-150
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• 2002

Recently the demand for electrical power is significantly increased due to the life improvement of customers. Correspond to the result, the transmission capacity is larger, also the fault current is significantly larger. Within the methods of limiting this fault current, the methods of using the fault current limiter is on the rise. If the Superconducting Fault Current Limiter(SFCL) is applied, then the power delivery loss doesn't exist between the plural power systems, also the fault current can be reduce. But for applying the real system, it needs to investigate the effect of SFCL before appling to real power systems. Consequently, the fault of transmission with SFCL was simulated using EMTP. It was investigated to the effect of SFCL at the 345[kV] transmission fault according to compare with the case of appling SFCL and removing SFCL.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1416-1418
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• 1999

This paper presents a restoration method by using Dijkstra algorithm for outage restoration problems in distribution system that considering load capacity constraints and operation constraints. Restoration problem in distribution system is difficult to solve problem in a short times, because of a distribution system that supplies power for customers combined with many tie-line switches and sectionalizing switches and have to satisfy plenty of operation conditions. Therefore, this paper applied Dijkstra algorithm which is satisfy radial operation conditions in distribution system. This proposed method used Kruskal algorithm include to Dijkstra algorithm Therefore, proposed method is restored to a outage sections in a short times and just then to satisfied with a operation conditions in distribution system. A 26-bus, 31-branch model system is used to demonstrate the effectiveness of the proposed method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.14-22
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• 2008

This study is aimed at suggesting a linear-type diffuser which is excellent in terms of range and elegance like existing diffusers in which amount and direction of wind can be freely controled, out of linear-type diffusers with the highest possibility to be adopted for living space of apartments whose height between floors is not so high and utilizing the linear-type diffuser in design. For the purpose, I examined necessary flow and noise properties of linear-type diffusers. Besides, I evaluated its ventilation capacity for persons in there by applying this in the actual living space. I evaluated features and air blast and found that in time of horizontal and vertical effusion, its T/L ratio is 1-1.5, similar to existing cardioid-type linear diffusers, while in time of slope effusion, it is similar to horizontal effusion in terms of range and it has medium figure in terms of pressure drop and effusion speed, indicating it can provide safe and pleasant indoor environment for persons in there in terms of ventilation.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.714-723
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• 1999

This paper presents a short-term scheduling algorithm for the operation of steelmaking processes. The scope of the problem covers refining of the hot iron transferred form a blast furnace, ladle treatment, continuous casting, hot-rolling, and coiling for the final products that should satisfy the given demand. The processing time at each unit depends on how much the batch amount is treated, and te dedicated intermediate storage with finite capacity between the units is considered. Resource constraints and initial amount of each state are incorporated into the presented scheduling model for the algorithm of on-line scheduling. We propose amixed integer linear programming (MILP) model with two objectives for the scheduling. The first is to maximize the total profit while atisfying the due date constraint for each product. And the second is to minimize the total processing time, makespan, while satisfying the demand for each product. Especially, we observe the effect of penalizing the intermediate storage and the inventory level of the final product on the scheduling results.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.93-98
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• 2010

In this paper, PLC which can be installed easily and is stable to transfer datum, is tested for approving its application in a real ship. Internet access service, CCTV monitoring, light control and huge sensor communications are needed for enhancing the convenience and safety of passengers and crew in ships. In order to apply PLC in ships, we surveyed some noises interrupting PLC in ships and investigated the PLC characteristics. The Hannara, a training ship of Korea Maritime University, was used for the test. We measured and analyzed blocking noises using by NI's SCXI-1001. When noises of specific frequency band occurred near the PLC frequency band, PLC transfer capacity was low for mass datum. We developed and verified some methods to apply PLC in a ship under lots of noises.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.804-808
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• 2007

when electric traction system used DC 1500V runs on decline of rail road track and slows down, Dc voltage goes beyond regular voltage. In this case extra power is forcibly wasted by resister because rectifier of substation and electric train including power converter and so on are out of order. This paper described a DC electric railway system, which can generate the excessive DC power form DC bus line to AC source in substation for traction system. The proposed regeneration inverter system for DC traction can be used as both an inverter and an active power filter(APF). As a regeneration inverter mode, it can recycle regenerative energy caused by decelerating tractions and as an active power filter mode, it can compensate for harmonic distortion produced by the rectifier substation. In addition, electric traction system products harmonic current and voltage distortion and reactive power because power converter is used so regeneration inverter normally runs such as active power filter(APF) for improving power quality. From the viewpoint of both power capacity and switching losses, the system is designed on the basis of three phase PWM inverters and composed of parallel inverters, output transformers, and an LCL filter.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1081-1099
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• 2010

The TVM 430 system manufactured by Ansaldo STS in France is currently used in ground signalling system for Kyungbu HSR. It transmits the speed information to the on-board signalling system in the form of continuous signal via the track, and the rolling stock in Kyungbu HSR runs with 300km/h max. operating speed by using the corresponding information. Looking from the recent international trends in HSR, reducing the travelling time and increasing of the line capacity is promoting via the improvement of train speed. In case of TGV Est, they are realizing the normal operation with 320km/h max. operating speed by using TVM SEI signalling system, which is similar to TVM 430. Furthermore, in case Honam HSL, which is under construction, is looking over faster speed than the limited one of Kyungbu HSR(i.e. over 300km/h). In this paper, it is assumed that the existing TVM 430 ground signalling system is used and train speed is improved, therefore the number of block section to be increased depending on the increase of train speed and the standard speed to be used in this case is drawn via the simulation of the train model and described the method accordingly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.71-78
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• 2017

Visible light communication (VLC) offers communication function in addition to illumination. Because the signal communication capacity per cable is 1,000 times compared to the power line communication (PLC), optical fiber is being advertised as the basis of the information and communication. Also dimming control of LED is an important component needed to provide energy savings and quality of life. This study configured multi-hop VLC system model in a building using optical fiber and analyzed the power performance of two of modulations using dimming techniques. The transmission power and received power were used to compare the power performance in multi-hop VLC environments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1752-1757
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• 2012

With the development in industry, power demand has increased rapidly. As consumption of power has increased, Demand for new power line and electric capacity has risen. However, in the event of fault, problems occur in extending the range of fault coverage and increasing fault current. In these reasons, protection devise is recognized as the prevention of an accident and fault current. This paper dealt with minimizing fault propagation and limiting fault current by adjusting fault current limiter (FCL) with fast interrupter. At this point, we compared and analyzed characteristics between non-inductive resistance and fault current which is limited by superconducting units. In normal state of the power system, power was supplied to the load, but when fault occurred, the interrupter was operated as CT which detected the over-current. Its operation made the limitation of fault current through a FCL. We concluded that the limiter using superconducting units was more efficient with the increase of power voltage. Superconducting fault current limiter with the fast interrupter prevented the spread of a fault, and improved reliability of power system.