• 한국항만경제학회지
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• 제24권4호
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• pp.199-217
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• 2008

항만선택 결정요인에 관한 선행연구를 정리해보면 매우 다양한 연구에서 결정요인들이 도출되었으며, 다수의 연구에서 주요요인들이 중복적으로 활용되고 있음을 알 수 있다. 그러나 연구자별로 조사대상의 입장과 선호도에 따라 다소 연구결과가 다르게 나타나고 있다. 따라서 화주들의 광양항 선택 결정요인을 도출하기 위해서는 문헌조사와 함께 적합한 실증적 연구와 분석이 요구되어 진다. 본 연구에서는 화주가 항만을 선택할 때 미치는 결정요인들을 선행연구를 통해 도출한 후, 도출된 결정요인들이 광양항을 이용하고 있는 화주들에게 미치는 영향을 실증적으로 분석하였다. 이를 위해 광양항 이용화주들의 지속적인 광양항 이용 여부를 종속변수로 설정하였고, 선행연구에서 도출된 항만선택 결정요인인 항만서비스, 항만시설, 항만입지, 항만비용 등을 독립변수로 설정하였다. 독립변수의 주요 요인을 살펴보면, 항만서비스 요인으로는 하역능력, 선박기항 빈도, 항만체선, CFS의 처리능력, 통관서비스, 항만정보 서비스 등을 변수로 설정하였다. 또한, 항만시설 요인으로는 항만의 규모, 적절한 하역장비의 보유, 화물의 손상 및 멸실 빈도 등을 변수로 설정하였으며, 항만입지 요인으로는 항만과의 접근성, 항만의 인지도 등을 설정하였다. 마지막으로 항만비용 요인으로는 내륙운송비, 항만시설사용료, 하역료, 무료장치기간, 인센티브 등을 변수로 설정하였다. 본 연구의 분석결과 광양항 이용 화주들은 항만서비스, 항만시설, 항만입지, 항만비용 요인에서 모두 광양항 선택에 영향을 미치고 있으며, 항만비용, 항만입지, 항만서비스, 항만시설 등의 순으로 중요도가 나타나고 있다. 이는 화주들이 항만시설보다는 항만비용과 항만의 입지, 항만서비스를 항만선택 시 주요한 고려요인으로 작용하고 있는 것으로 판단된다.

• Journal of electromagnetic engineering and science
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• 제16권4호
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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.

• 한국항해항만학회지
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• 제31권6호
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• pp.545-553
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• 2007

글로벌 생산네트워크의 변화로 인해 우리나라 주요 항만은 새로운 전략의 수립이 요구되고 있다. 무역 패턴의 변화로 인해 중국, 일본, 한국을 포함한 아시아의 경제적 성장이 급속히 이루어지고 있는 상황에서 동북아에 집중되는 항만 물동량을 흡수하기 위해 우리나라 중심 항만들의 환적기능 강화가 필요한 시점이다. 특히 동북아 포트얼라이언스를 활용한 환적기능 강화는 변화하는 무역환경에서 우리 중심항만들이 경쟁력 확보를 위한 기회가 될 수 있을 것이다. 따라서, 본 연구의 목적은 부산항과 광양항 같은 우리나라 주요 항만들의 환적기능을 촉진하기 위한 포트얼라이언스 전략을 제안하고자 하는 것이다. 두 주요 항만의 물류비즈니스 모델 수립을 위해 동북아 포트얼라이언스의 방향과 중국과 일본의 후보 항만들을 제시하였다.

• 한국항만학회지
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• 제11권2호
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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.

• 한국자동차공학회논문집
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• 제11권3호
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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.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 추계학술발표논문집
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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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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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.

• 한국항만경제학회지
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• 제21권4호
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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.

• 수산해양교육연구
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• 제10권1호
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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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• 제19권10호
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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.