• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.199-217
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• 2008

Many studies have identified the determinants of shippers' selection of ports, and of these, a number have repetitively cited major elements. However, different researchers came up with somewhat different research results depending on the position and preference of research targets. Accordingly, to deduce the determinants of shippers' selection of Gwangyang Port, appropriate research and analysis is required in addition to literature study. This study first deduced from previous studies the determinants that have influence on shippers when selecting a port and positively analyzed the effects of those determinants on the shippers using Gwangyang Port. In this regard, whether shippers using Gwangyang Port have continuously used the port was set as a dependent variable, and port service, port facilities, location of ports, port costs, and other determinants for port selection deduced in the previous studies were set as independent variables. This study's analysis finds shippers using Gwangyang Port are all influenced by the elements of port service, port facilities, location of ports, and port costs in their selection of Gwangyang Port. Their degree of importance is in the order of port costs, location of ports, port service and port facilities. This indicates that shippers consider port costs and location of ports more important than port facilities in their selection of a port.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.206-209
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• 2016

This letter proposes a reconfigurable directional coupler that uses a variable impedance mismatch reflector to achieve high isolation characteristics in the antenna front end. The reconfigurable coupler consists of a directional coupler and a single-pole four-throw (SP4T) switch with different load impedances as a variable load mismatch reflector. Selection of the load impedance by the reflector allows cancellation of the reflected signal due to antenna load mismatch and the leakage from the input to isolation port of the directional coupler, resulting in high isolation characteristics. The performance of the proposed architecture in separating the received (Rx) signal from the transmitted (Tx) signal in the antenna front end was verified by implementing and testing the reconfigurable coupler at 917 MHz for UHF radio-frequency identification (RFID) applications. The proposed reconfigurable directional coupler showed an improvement in the isolation characteristics of more than 20 dB at the operation frequency band.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.545-553
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• 2007

Due to the change of global production network, the establishment of new strategy in Korea ports is required Especially, the trade pattern has been mainly concentrated in Northeast Asia region according to economic growth of the Asia including China, Japan, and Korea. Hence, Korea major ports with the competition of price and service has to meet the need of Northeast port alliance and has to compete against other countries in variable trade environment. Therefore, the objective of this study is to propose a port alliance strategy in order to promote the transshipment of Korea major ports such as Pusan port and Gwangyang port. In order to establish the logistics business model in the ports, we provided the direction of the Northeast port alliance and candidate ports in China and Japan.

• Journal of Korean Port Research
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• v.11 no.2
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• pp.273-280
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• 1997

Recently the importance of the cargo handling equipments in a port has been increasing to get strong competition from other ports. Many ports are making efforts to modernize their cargo handling equipments. The kernel technology of such equipments is the speed control of DC motor which is used as an essential part of them. In this paper, we discuss the speed control of a DC motor as a basic work for building cargo handling equipments in a port. DC Motors are still widely used in industrial fields, as driving power motor for electrical fields. DC drives, being easy to control, are widely used in many variable-speed and position control drive system. Traditional analog control circuits used in such applications have many disadvantages. Complex control schemes are difficult to implement with analog components. All these factor and invention of the microprocessor has made it possible to use digital control circuits, using microprocessing system. These digital circuits have been found to be reliable, flexible, and also immune to noise. In this paper it presents the speed control of a SCR DC motor driver which using dual converter by 80c196kc microprocessor. We developed a thyristor power amplifier which does not cause damage thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was analyzed voltage and currents wave at reactive load.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.106-114
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• 2003

The pressure ripple in the delivery port is caused by flow ripple, which is induced by variation of pumping chamber volume. The other reason is the reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume, when the pumping chamber is connected with the outlet volume. In this study, a mathematical model is presented for analyzing discharge pressure ripple, which includes vane detachment, cam ring movement , and fluid inertia effects in V-groove in the side plate. From the analysis and experiment, it was found that V-groove on the side plate, coefficient of spring supporting the cam ring, and average discharge pressure are the main factors of discharge pressure ripple in variable displacement vane pump. The theoretical results, provided in this study, were well agreed with experimental results. The analytical model to estimate the magnitude of pressure ripple in this study is expected to be used f3r the optimal design of the variable displacement vane pump.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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• pp.95-99
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• 2000

The domestic ports become less competitive for the out of dated equipments and inefficient information system. Specially, Inchon Port, which is the second largest port of Korea, has the point at issue such as the excessive logistics cost because of the limit of handling capacity and the chronic demurrage. In this paper to develope the simulation programs the basic input parameters such as arrival intervals, cargo tons, service rates are analyzed and the probability density functions for there variable are estimated. Also to perform the conception of continuous berth utilization, the berth and cargo classification is reconstructed. And the more actual simulation is realized by using more detailed depth representation of water The simulation model is executed based on the knowledge base and database, and is constructed using Visual Basic and Access database. Simulation results reveal that this study suitably reflect the real berth operation and waiting time of ships is shortened.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.59-60
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• 2007

Entropy, one of leading metrics on anomalous traffic, attracts researcher's attention since a packet sampling and a traffic volume impact little on entropy value. In this paper, we apply the entropy metric to a domestic network traffic trace which has real anomalous traffics. We used source IP address/port and destination IP address/port that are important attributes of a packet as entropy variable We found that entropy value of multiple-port DoS attack shows something related to a staircase fashion. Also, we show a Possibility of detection of anomalous traffic on small time scale.

• Journal of Korea Port Economic Association
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• v.21 no.4
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• pp.239-253
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• 2005

Although logistics service quality is considered an essential strategy for success and survival in today's internet environment, there are still a lot of question: what variables determine the extent of logistics service effect, how difficultly do the determinants affecting logistics service effect and how accomplish the decision making in the implementation of inter-organization information system. The purpose of this study is to examine a model to utilize the application and effect of logistics service through e-marketplaces. The results of empirical analysis are mentioned as follows; First, among the interorganization information system factors, four variables(top management support in organization characters, competitive degree in environment characters, relative advantage and information efficiency in innovation characters) have been shown to be primary determinant of the effect of logistics service quality. Second, the type of independent variable used results in a significant difference in the effect of logistics service quality. Third, Korean firms have to pursue the corporate strategy focused on logistics service quality.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.1-14
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• 1998

Transportation provides an infrastructure vital to economic growth, and it is also an integral part of production. As a port is regarded as the interface between the maritime transport and domestic transport sectors, it certainly play a key role in any economic development. Ship's delay caused by port congestion has recently has recently attracted attended with the analysis of overall operation in port. In order to analyse complicated port operation which contains large number of variable factors, queueing theory is needed to be adopted, which is applicable to a large scale transportation system in chiding ship's delay in Inchon port in relation to ship's delay problem. The overall findings are as follows ; 1. The stucture of queueing model in this port can be represented as a complex of multi-channel single-phase 2. Ship's arrival and service pattern were Poisson Input Erlangian Service. 3. The suitable formula to calculate the mean delay in this port, namely, $W_q={\frac{{\rho}}{{\lambda}(1-{\rho})}}{\frac{e{\small{N}}({\rho}{\cdot}N)}{D_{N-1}({\rho}{\cdot}N)}}$ Where, ${\lambda}$ : mean arrival rate ${\mu}$ : mean servicing rate N : number of servicing channel ${\rho}$ : utilization rate (l/Nm) $e{\small{N}}$ : the Poisson function $D_{(n-1)}$ : a function of the cumulative Poisson function 4. The utility rate is 95.0 percents in general piers, 75.39 percents in container piers, and watiting time 28.43 hours in general piers, 13.67 hours in container piers, and the length of queue is 6.17 ships in general piers, 0.93 ships in container piers, and the ship turnaround time is 107.03 hours in general piers, 51.93 hours in container piers.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1939-1949
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• 2005

Many studies have been conducted to increase regression rate of solid fuel in hybrid rocket. One of them resorts to swirl flow since it can extend the residence time of oxidizer in the fuel grain. Also, metal wires may lead to increase the regression rate of solid fuel as shown in solid propellants. In this study, a series of experiments was designed to investigate the enhancement of regression rate of solid fuel by embedded metal wires and by fuel port grain. And fuel port was designed with a helical configuration to attempt to induce swirl flow. PMMA with gaseous oxygen is the solid fuel used for investigation. Test results showed that embedded metal wires turned out to be ineffective method because only $3-4\%$ increases in regression rate were observed. However, fuel port grain configuration yields higher burning performance of up to $50\%$ increase in regression rate. Also pitch number as well as total impulse was found to be a design variable.