• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.609-615
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• 1987

The optimal operation of power system is developed by alternately using real power dispatch and reactive power dispatch problem. The real power system scheduling process is formulated as an optimization problem with linear inequality constraints. A.C. loadflow method is used for the problem solution and line losses are considered. The constraints under consideration are generator power limits, load scehdling limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time application. The reactive power control problem uses the Dual Simplex Relaxation method as in the real scheduling case. Insted of minimizing the cost of power system, the objective is selected as to determine the highest possible voltage schedule. The constraints under consideration are the voltage limits at each node and the possibilities of supply or absobtion of reactive energy by generator units and the compensation facilities. Tests indicate that the method is practical for real time applications. The overall optimization methods developed in this paper proved to obtained fine results in minimizing object function compared with the method without using voltage control. And the overall voltage profiles were also improved.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.447-462
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• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.319-324
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• 2006

Studied was a strategy of technology development for railway system in terms of railway network. First, The successful launch of the Korean HST system has not only decreased logistics burden but also significantly transformed the Korean trunk-line railway network, revolutionizing the logistics and technology sectors and reinvigorating the Korean railway industry in one century. Korean railway industry sector is now investing to develop many different types of railway system(G7, Post G7, tilting train...) so that these kinds of various railway system development should be integrated with the National Inter-modal Transportation Network Plan. To secure sufficient capacity that is required by the National Railroad Plan, the railway industry needs to establish mid- and long-term train purchase and operation strategies in compliance with railway construction and operation policies. During a railway construction planning, train operators, based on their train operation strategies, should come up with measures to closely cooperate with project operators from the planning stage through to the opening of a railway system. To be more precise, train operators should establish long-term train procurement plans reflecting both long-term national railroad network plans and plans for each railway line in order to suggest appropriate roles and schedules for each line. Also, based on the long-term railway plan, directions should be decided concerning the research and development of trains in advance.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.06a
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• pp.177-184
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• 2002

In these day, the storage capacity has been growing and the informations increase in geometrically progression in a modem information age. At present the situation is required that the exchanges and access of the informations is available without regard to time and space. In this paper we present a effective backup systems to backup the information of server that continuously has to be accessible in 365's days. There are two backup cases. one is a file-base backup and the other is a block-based backup. In general, a block-based backup has a good performance than a file-based backup but it is difficult to implement a block-based systems. First, we introduce the technique of backup and methods, on-line backup. Next, we present our backup systems based on client-server model and have a snapshot facility. Finally we introduce SCSI-Protocol in order to increase the data transfer rate.

• Korean Journal of Health Education and Promotion
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• v.20 no.1
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• pp.61-76
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• 2003

As people get broader access to health information through the internet, there is a greater need for measure to maximize the social advantages of the internet and to minimize negative side-effects. With this concern, this paper classifies internet health information services sites into : on-line supply of health information, on-line consultation, on-line diagnosis, and on-line sales. As well this paper analyzes domestic laws supporting and/or regulating these services. The efficient provision of internet health services requires comprehensive laws on individual privacy protection, prevention and handling of medical accidents, an electronic prescription form for internet diagnosis, electronic signing, payment for medical expenses, qualifications for internet medical practitioners. Additional laws are required to establish internet pharmacies and internet health goods stores. These new laws can be prepared either separately or through revision of existing laws governing medical practice, pharmacies, and public health promotion. However, as the legal control by the government on cyber processes and entities has a fairly minimal effect, consumers should be encouraged to improve their own capacity for wisely using internet health services and health-service providers should be encouraged to promote voluntary supervision and control of their own services and practices.

• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.31-39
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• 2005

This paper illustrates a tie line constrained equivalent assisting generator (TEAG) model considering forced outage rates of transmission systems for reliability evaluation of interconnected power systems. Interconnections between power systems can provide improved levels of reliability. It is expected that the TEAG model developed in this paper will prove useful in the solution to problems related to the effect of transmission system uncertainties in the reliability evaluation of interconnected power systems. It is important that interconnection between power systems can provide the improved levels of reliability. Therefore, It is expected that the TEAG model developed in this study will provide some solution among many problems for interconnected power systems as an optimal tie line capacity and a connected point between assisting systems and assisted system. The characteristics and validity of this developed TEAG considering transmission systems are introduced by case study of three IEEE MRTS interconnected.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1818-1823
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• 2015

In this paper, we analyzed the optimal configuration of protection wire that have been installed in the electric railway power supply system. Protection wires are to suppress the ground potential rise when the short circuit fault between contact wire-rail(C-F), and protect the electronics equipments(signalling and communication) that are facility the wayside. The role of protection wires must be feed back quickly the fault current to the substation when a short circuit fault occurs. In this paper, we proposed that only one line to install the protection wire. Comparing how to newly proposed and existing system, most of the performance is similar. The reason is that most of the current flowing in the protection wire near the location where the fault occurred. There is no problem even if in one line for human safe and the low impedance of the return circuit in dimension to ensure the safety of the facility during the fault. To ensure safety during an fault occurs, it is sufficient even by one line. But, In the protection wire of facilities planning it is necessary to design taking into account the potential utility.

• Journal of Korean Society of Transportation
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• v.18 no.3
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• pp.29-39
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• 2000

Position of stop line according to left turn trajectory at intersections was studied. The Purpose of this study is to suggest a design guideline of left turn trajectory at intersections which is related to the Position of cross road stop line. Distance from the curb line to the stop line at each lane was calculated and discussed for various combination of road widths. Three design vehicle type and three control radii were considered. Setbacks of stop line from the curb line are Proportional to the control radius which depends on type of design vehicle. 8m, lim and 19m setback for control radius of 12m, 15m and 23m were calculated respectively as their maximum value. This result will be helpful to Paint the road marking on the Pavement which is usually difficult to fit to the designated radius. Field study of the effect of left turn trajectory on flow rate and safety was conducted. It was approved that improperly designed left turn trajectory decreases left turn capacity and increases conflicts among left turn flows of the adjacent lane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1016-1022
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• 2010

An Experimental study of cleaning solution has been performed on a high capacity steam boiler burning heavy fuel oil to on-line cleaning of deposit. The deposit is mixture of soot, slag, ash, metal oxide and clinker. The traditional technology of deposit cleaning was carried hand-crafted. The conventional technology of boiler cleaning method is mechanical removal by the worker while the boiler shut down operation. In this experiment, the deposit of mixture of soot, slag, ash, metal oxide and clinker has been removed by the cleaning agents without shut down of boiler burning. This study found out the optimum cleaning solution composition. The best results have been obtained when the mixture of ammonium nitrate and $MgNO_3$ were used in cleaning solution. The various transition metal effect was investigated for optimum mixing condition. In this research, the metal compound additive of the clean solution compoition was obtained. The combustion efficiency was improved by on-line cleaning with derived clean solution compoition. On-line cleaning method prevents the fouling and corrosion in the boiler and heat exchanger.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.269-278
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• 2011

This study aims at setting up productive capacity which can be usefully utilized for work management of apparel manufacturers. So as to achieve this goal, an apparel manufacturing company which has been operated by miniline system in Seoul was selected. Standard time and man-hour were calculated to create the accurate productive capacity by observing and measuring a work flow included cutting, sewing and finishing processes. And the result is as following. The standard time for each process was presented as cutting process 47004.5s, sewing process 671050.5s and finishing process 22426.3s. And 15284.4ms was computed as total procession man-hour per day of the manufacturer which is organized of 16 people. Also, the procession man-hour for each process was revealed as cutting process 396.7ms(2.6%), sewing process 14509.3ms(94.9%) and finishing process 378.5ms(2.5%). +Surplus was found in the productivity for each process included the cutting process(outshell, lining and seam process), the sewing process(preparation and arrangement process) and the finishing process. But, additional man-hour 52436.18ms was required because the productive capacity was calculated as -surplus(-13.9%) in the sewing process(part and assembly process). Therefore, a work schedule was planned based on the previous result. However, loading can be ideal when a capacity and a load become '0'. The object company should find the way to reduce allowance(26.25%) of the sewing process through reconstruction of consciousness and improvement in functions with analyzing works of operators. Also, they need to consider an additional supplement of the personnel.