• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.248-254
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• 2001

The traction power demand highly varies with time and train positions and the traction load is a large-capacity current at single phase converted from 3-phase power system. Subsequently, each phase current converted from 3-phase power system cannot be maintained in balance any longer and thus the traction load can bring about imbalance in three-phase voltage. Therefore, the exact assessment of voltage unbalance must be carried out preferentially as well as load forecast at stages of designing and planning for electric railway system. The evaluation of unbalance voltage in areas, such as electric railway depots should be a prerequisite with more accuracy. The conventional researches on voltage unbalance have dealt with connection schemes of the transformers used in ac AT-fed electric railroads system and induced formulas to briefly evaluate voltage unbalance in the system(3). These formulas are still being used widely due to their easy applicabilities on voltage unbalance evaluation. Meanwhile, they don't take into account detailed characteristics of ac AT-fed electric railroads system, being founded on some assumptions. Accordingly. accuracy still remains in question. This paper proposes a new method to more effectively estimate voltage unbalance index. In this method, numerous diverted circuits in electric railway depots are categorized in three components and each component is defined as a two-port network model. The equivalent circuit for the entire power supply system is also described into a two-port network model by making parallel and/or series connections of these components. Efficiency and accuracy in voltage unbalance calculation as well can be promoted by simplifying the circuits into two-port network models.

• Journal of Navigation and Port Research
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• v.30 no.9
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• pp.729-734
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• 2006

The authors aim to establish the theory necessary for developing the free gyroscopic compass and focus on mainly two points. One is to suggest north-finding principle by the angular velocity of the earth's rotation, and the other is to suggest orthogonal coordinate transformations of the motion rate of the spin axis, which transforms the components of motion rate in the free gyro frame into those in the platform frame and that this transformed rate is, in turn, transformed into the NED(north-east-down) navigation frame. Subsequently, ship's heading is obtained by using the fore-aft and athwartship components of the motion rate of the spin axis in the NED frame. In addition it was found how to solve the transformation matrix necessary for transforming each frame.

• Journal of Korea Port Economic Association
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• v.20 no.1
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• pp.141-151
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• 2004

Although the small and medium ports are actually competing with various strategies, the definition and structural understanding of small and medium ports are not known very much. Therefore this study has launched from this fact, and has the objective of obtaining the structural model for increasing shippers' attraction of small and medium ports. The process began by abstracting the components that composed the success factors through recent research, and grouping it by FA(Factor Analysis) method. Also, by using the FSM(Fuzzy Structural Modeling) method to understand the structure of the grouped components, and the structural model for increasing shippers' attraction of small and medium ports was able to obtain as the result. When analyzing the obtained structural model, easiness of shipment, connection to hubport and efficiency of hinterland network came out to be the most important component groups.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.321-332
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• 2004

The purpose of this research is to introduce the concept of "relationship formation factors" in inter-firm relations and to empirically demonstrate that they are effective in improving the relationship results by means of anmediating variable. Therefore, the basic model of this study consists of the independent, mediating, and dependent variables. First, the independent variable, that is, the relationship formation factors, is further classified into three components： transactional, relational, environmental characteristics. Then, the study empirically examines how each of the three components influences the dependent variable, that is, the business performance(Load Factor), by way of the mediating variables, that is, trust and relationship commitment.

• Journal of Navigation and Port Research
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• v.28 no.5
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• pp.373-384
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• 2004

The purpose of this research is to introduce the concept of "relationship formation factors" in inter-firm relations and to empirically demonstrate that they are effective in improving the relationship results by means of an mediating variable. Therefore, the basic model of this study consists of the independent, mediating, and dependent variables. First, the independent variables, that is, the relationship formation factors, are further classified into three components. transactional, relational, and environmental characteristics. Then, the study empirically examines how each of the three components influences the dependent variable. that is, the business performance(Load Factor), by way of the mediating variables, that is, trust and relationship commitment.

• Journal of Korea Port Economic Association
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• v.22 no.1
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• pp.87-103
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• 2006

The aim of this paper is to establish the evaluation system of improving urban logistics using the QFD(Quality function Deployment) model which can facilitate to grasp the improving degree of realizing the system conforming to the relationship of all process and the process improvement. At the first stage, the established system through the QFD method will be used to evaluate and diagnosis the level of urban logistics in Cheonbuk District. The second stage is to investigate the important components that can make prompt improvement of urban logistics. Then, the sensitivity analysis is to be performed and the degree of improving urban logistics will be presented according to the rising degree of the relevant components.

• Journal of Korean Port Research
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• v.13 no.1
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• pp.27-40
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• 1999

This study aims to apply and examine the stochastic approach for empty container repositioning and leasing problem. For this a case study has been carried out on actual data such as various cost components and traffic flow. The results reveal that the proposed methodology produces more realistic results than the conventional deterministic approaches. It is also found that the results are significantly affected by the accuracy of demand and supply forecast.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.109-118
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• 2017

This study was conducted to investigate the effects of intermittent plasma and electrolysis treatments on lettuce (Lactuca sativa var. oak-leaf.), nutrient solution components ($NO_3{^-}-N$, $NH_4{^+}-N$, $PO{_4}^{3-}-P$, $K^+$, $Ca^{2+}$ and $Mg^{2+}$) and environmental parameters (electrical conductivity, total dissolved solids and pH). The recirculating hydroponic cultivation system consisted of planting port, LED lamp, water reservoir and circulating pump. Nutrient solution was circulated in the following order: reservoir ${\rightarrow}$ filtration-plasma or filtration-electrolysis ${\rightarrow}$ planting port ${\rightarrow}$ reservoir. The results showed that nutrient solution components and environmental parameters were changed by plasma or electrolysis treatment. Lettuce growth was not affected by the intermittent plasma or electrolysis treatment with 30 minutes or 90 minutes, respectively. The roots of the lettuce was damaged by excessive plasma and electrolysis treatment. Electrolysis treatment had greater effect on than plasma treatment because of the accumulation of high levels of TRO (Total Residual Oxidants).

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.569-576
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• 2003

Although the Free Trade Zone(FTZ) are actually competing with various strategies, the definition and structural understanding of activation strategies are not known very much Therefore this study has launched from this fact, and has the objective of obtaining the structural model for activation strategies in Gunsan FTZ, and understanding the components of activation in these region The process began by abstracting the components that composed the success factors in FTZ through recent research, and grouping it by the most core components. Also, by using the FSM(Fuzzy Structural Modeling) method to understand the structure of the grouped components, and the structural model for activation of FTZ was able to obtain as the result. When analyzing the obtained structural model, expansion of tax reduction, flexibility of law systems and good business environment came out to be the most important component groups, and especially flexibility of law systems and good business environment were the most effective component that effected all the other components overall.

• Journal of Navigation and Port Research
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• v.36 no.3
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• pp.189-196
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• 2012

Recently constructed several floating buildings, in Korea, provoked the discussion about the activation of floating architecture. But, there is no guideline for the planning of floating architecture in Korea. This study aims to propose the framework of planning guidelines for the superstructure of floating architecture. For the purpose, collected various exiting guidelines related to floating architecture, and then analysed the structure and components of those guidelines. As a result of analysis, many components, could be used as references, are extracted. After the classification of the components into several categories, then, compared the content of components, derived from different guidelines, in same category. Based on the former analysis and comparison, proposed the framework of planning guidelines for the superstructure of floating architecture, consist of various set of components.