• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.451-465
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• 1987

With the introduction of ISDN network, the D channel protocol has bee defined as a signalling method for ISDN user-network interface. Therefore the NT2(Network Termination 2) which carry out concentration and switching function, must process the D channel related information. This paper describes how the D channel protocoal is applied and implented in a small ISDN subscriber concentrating system that has NT2 functions. The application protocol proposed is addressed taking into consideration the compatibility with ISDN standard facilities, TE(Terminal Equipment) or ET(Exchange Terminator), This protocol has been implementes using a general multitask operating system and it has the features of the minimized information processing and the simpified algorithm which are suitable for a small system. Its application programs are divided into various tasks to facilitate the addition and the modification of function. In this paper, we briefly outline the protocol defined in CCITT and show the application protocol that has fitted in a small concentrating system with NT2 functions. Also we present the experimental results and implementation method of this protocol.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.215-232
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• 1999

Privatisation has emerged within the past few decades as one of the most significant challenges to public ports and their governments throughout the world. More than forty countries have committed to some form of port privatisation thus far and they will quite likely be joined by dozens more by the turn of the century. A decision to privatise ports can be driven by a variety of forces. The most obvious is to relieve a financially strapped government by turning to the private sector for an infusion of capital required to modernise and sustain port operations, or to bolster the national treasury. Inefficient and costly port operations can seriously impair the competitiveness of a nation’s export industries and artificially raise the cost and thus constrain the availability of imported goods. Privatisation in certain circumstances therefore holds the promise of stimulating economic growth particularly for those whose livelihood depends directly upon port activity and trade. The main objective of this paper is first of all, to introduce a variety of methods of port privatisation after reviewing the reason why port facilities should be privatised. This paper also aims to make some proposals with which a port privatisation process in Korea can be improved after summarising the present Terminal Operating Company(TOC) system propelled by Ministry of Maritime Affairs and Fisheries.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.31-40
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• 2003

Because yard monitoring system is a part of real-time operation system and yard planning system, most planers, in container terminal, Busan Port, can not consider real-time and exact yard situation and container information such as position of equipments or movement of container with current planning system when export yard planning os established. Therefore, many planers recognize the limit of current planning system and try to find the solution to get over it. The reason of this, heuristic algorithms for the export yard the limit of current planning ,operating on monitoring system, are suggested and integrated export yard planning system is designed and developed in this paper.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.223-231
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• 2003

In this paper, we present a scheme for developing a simulator which verify the AGV system operation in automated container terminal. First of all, we propose a guide path in automated terminal considering AGV productivity and present a traffic control scheme in a such guide path. Generally, the AGV system can be controlled by zone control scheme, but there are no flexibility and use simple operation. In this paper, we propose and use grid based control scheme to improve the flexibility of the AGV movement. Lastly, we construct the simulation environment which can do similar to that of real task and ease the modification and improvement of the control logics.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.245-254
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• 2014

Payment system is defined as the various contracts and operating facilities for the transfer of monetary value to clear the relationship between credit and debt. Payment systems essentially require the efficient and reliable operations. Card-based payment systems are developed practically and creatively in accordance with the progress of ICT. Especially in mobile environment with intelligent mobile devices such as smart-phones and tablets, a variety of payment services are provided. Existing card-based payment services are configured by the payment transaction initiated by the merchants card acceptance and then swiping into the CAT (Card Authorization Terminal) to begin the transaction. The merchant initiated payment services are now applied to the Wireless CAT (W-CAT) for mobile environment. That kind of payment services cause many problems such the illegal card information leaks and the lingering threat of W-CAT theft. Also, the use of many W-CATs increased cost to the merchant. In this paper, we propose the card holder initiated card payment system using the intelligent mobile devices in mobile environment for solving problems of the existing merchant initiated card payment system and coping effectively with the activation of a wireless data network and changes of information technology.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.53-60
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• 2005

The wire rope of container crane is a important component to container transfer system and is used in a myriad of various applications such as elevator, mine hoist, construction machinery, and so on. If it happen wire rope failures in operating, it may lead to the safety accident and economic loss, which is productivity decline, competitive decline of container terminal, etc. To solve this problem, we developed the active and portable wire rope fault detecting system. The developed system consists of three parts that are the fault detecting, signal processing, and remote monitoring part. All detected signal has external noise or disturbance according to circumstances. Therefore we applied to discrete wavelet transform to extract a signal from noisy data that was used filter. As experimental result, we can reduce the expense for container terminal because of extension of exchange period of wire rope for container crane and this system is possible to apply in several fields to use wire rope.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1106-1118
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• 2006

The Internet has become an important instrument for providing many pieces of information to us. And server systems offer the various services after processing a volume of information, it's network topology also has been complex for providing information. Therefore this expansion means the importance of fast and sustained management of server systems. But most of server systems are located in fire-walls to allow only restricted access. Moreover, due to the difference of management based on the different operating system of each server system, management of server system is not to efficiency. That is, sever administrators have to manage by themselves many kinds of servers by using local-based or socket-based single access applications. Therefore, we design and implement a middleware system which allows to manage many kinds of severs integrally ruling XML-based Web Services which have distributed object technology such as CORBA, Java RMI and DCOM, but are free from platforms or development languages. System also provides location transparency and terminal independence and calls a server system management command to manage systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.60-67
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• 2002

In this paper, the dual band VCO of mobile communication terminal using oscillation part switching circuit is proposed. In order to model the VCO accurately, the resonator is converted the equivalent circuit which is analyzed to use numerical method and designed optimal the dual band VCO operating GSM and DCS band. In order to demonstrate the objective theory of the proposed VCO, the dual band VCO is designed and experimented. The results of experiment, it is conformed that the VCO can be used mobile communication hand phone and components of three generation mobile communication systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.708-717
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• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.139-144
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• 2008

Recently due to march as the high oil price, It is necessary for Korea to grope a plan, which is to increase the energy efficiency of existing facilities as well as to develop overseas gas and oil resources. With this point, this work carried out to approach the high pressure LNG pipeline network of Inchon receiving terminal with Newton method as corrective flowrate. We found that the high pressure network mainly depends on FCVs(Flow Control Valves). The high pressure pump showed the maximum efficiency at the FCVs of 50% opening and could discharge LNG only above the LNG head of 1,500m from a system curve obtained. The operating cost of pumps was estimated from their operating points. We compared the operating cost under normal operation with the operating cost under maximum efficiency. Especially, we obtained the day savings of a year as wells as the hour savings of a day. From the results, the high pressure network win be able to reduce the operating cost of 138 million wons in a year. This means that a pump can reduce the operating cost of 9,823 thousands won. Consequently, this work could find the operating features of the pumps under the complicated high pressure LNG network and the savings effect of the pump operating cost. Also, the results will be able to macroscopically contribute the heightening of national energy competitiveness as well as to microscopically contribute the future effective operation of LNG receiving terminal.