• KIEE International Transactions on Power Engineering
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• v.2A no.3
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• pp.83-88
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• 2002

An over current relay(OCR), one of the most frequently used protective devices, has time-current characteristics (TCC) to control its trip time according to the current level. It is because an appropriate operating time interval is necessary for coordination with other protective devices. A set of TCC curves of an OCR is, in general, given by the supplier from which a curve is selected by the operator. Therefore, in many cases, it is impossible to consider the operation condition of the given power system exactly. A novel concept of an OCR is suggested in this paper. The proposed OCR has an internal correction module so that it may produce the most adequate TCC curve according to the given protective information for coordination with other devices. With the generated TCC curve, a variety of operation and coordination conditions can be taken into consideration in an effective manner. The suggested OCR is applied to a simple test power system to show very promising results from a coordination point of view.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.807-809
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• 1998

Plant Protection Systems(PPS) are those systems that initiate safety actions to mitigate the consequences of design basis events by sending signals to Reactor Trip Switch Gear System(RTSS) and Engineered Safety Features-Component Control Systems(ESF-CCS). This paper illustrates distinctive features and improved design concepts of Korea Next Generation Reactor(KNGR) based on the experience obtained through prototyping of PPS.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.50-52
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• 2002

Distance relays need accurate current and voltage for determining the trip ignition. Therefore we must analyze nonlinear phenomena which cause distortion in signals first of all. This paper presents the effect of some distortion(arcing fault and current transformer saturation) in power system. The saturation of a current transformer distorts input current of a distance relay and arcing faults make current and voltage to be changed. This paper describes modeling methods of a current transformer and arcing faults, and describes the simulation result of two distance relay algorithms (discrete fourier transform and modified differential equation methods)

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.616-623
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• 1999

Elevator velocity pattern is basL'C! on combining the time-based velocity pattern according to which the car m trip from starting position to vicinity of target position, and distance-based velocity pattern for precise landing ( of car. To obtain the lide comfortability, the impact caused by velocity pattern switching should be minimizLD b by removing the discontinuity of velocity and acceleration. In this paper, new velocity pattern generation m method which ensure the continuity of velocity and acceleration during pattern switching is proposed. P ProPOSLD velocity pattern also shorten the landing time to the target position.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.7-15
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• 2008

Due to the limitations in the statistical data, the existing studies adopted rough methodologies with strong assumptions in the estimation of international passenger travel demand forecast in the ASEAN region. This study aims to develop international passenger travel demand models using scientific methodologies. This study proposes a direct demand model using the immigration and emigration data between countries in the region. This is because of the difficulty of estimating trip generation and trip distribution separately due to the data limitation in the region. As there does not exist the mode choice model for the region, this study estimates a mode choice model using the Stated Preference technique. The mode choice model is separated into three categories of models according to the range of distance between the origin and destination of travel; this is to reflect the different behavior in mode choice according to the travel distance. The result of model estimations suggests that the estimated models produce resonable results statistically. It is expected that the proposed models are useful for the future travel demand estimation in the ASEAN region.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.71-78
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• 2007

The purpose of this study is to analyze the social behavior, especially, the evacuation-related social behavior, of the transients in the radiological emergency planning zone(EPZ) of nuclear power plants. So, the meaning and kinds of the evacuation and the significance of the trip generation time(TGT) have been reviewed. The characteristics of the social behavior of the transient around Ulchin, Wolsong and Kori sites was analyzed through field surveys by using the questionnaire. The major findings of this research implications are as follows. First, for securing the safe evacuation, the alternatives to effectively provide the information on the evacuation warning may be prepared. Second, it is necessary to establish the education and training of transient's evacuation. Third, it is needed that the cause and background of the evacuation refusal are identified and the new response plan to secure transient's safety is prepared.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.2
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• pp.1-10
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• 1982

Presently, most of rail stations are situated on the surface of dowl1town and thus result in heavy traffic congestion and inefficient use of land. This paper analyzes the impact of alternative locations of station On urban traffic patterns by simulating transportation systems, of Busan city. Since location of station has long-term effects on land use and transportation, 20 years forecast of land use change, trip generation, trip distribution, modal split and network assignment was performed for each alternative, and aggregate Impacts On passenger-km and passenger-hour were computed. The result indicated that Bujeon is the most desirable location of station in terms of traffic movement, compared to the alternative locations of Sasang and existing station. Relocation of rail station, however, should be decided with broader analysis including other aspects, such as urban development, environment, construction and operating costs, etc.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.81-88
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• 2008

This paper presents the travel demand estimation using interval estimation methods during the trip generation stage, and then followed the other three stages of the four stage trip estimation. We have used real data of Dae-jun City. To estimate travel demand using the interval estimation method, a reliability level was set to 95% by a upper bound value, a middle value and a lower bound value. The four stage traffic demand analysis procedure was equally applied and finally interval traffic was estimated. The result showed a difference between maximum values and middle values depending on the destination during the trip generation stage. It depends on an explanation ability of regression analysis. Most of interval estimation ratio resulted in the traffic assignment stage showed ${\pm}5{\sim}18%$ difference on the average and ${\pm}30{\sim}50%$ at the most.

• Journal of The Korean Association For Science Education
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• v.27 no.9
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• pp.818-831
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• 2007

Recognizing the importance of abductive inquiry in Earth science, some theoretical approaches that deploy abduction have been researched. And, it is necessary that the abductive inquiry in a geological field excursion as a vivid locale of Earth science inquiry should be researched. We developed a geological field trip based on the abductive learning model, and investigated students' abductive inference, thinking strategies used in those inferences, and the impact of a teacher's pedagogical intervention on students' abductive inference. Results showed that students, during the field excursion, could accomplish abductive inference about rock identification, process of different rock generation, joints generation in metamorpa?ic rocks, and terrains at the field trip area. They also used various thinking strategies in finding appropriate rules to construe the facts observed at outcrops. This means that it is significant for the enhancement of abductive reasoning skills that students experience such inquiries as scientists do. In addition, a teacher's pedagogical interventions didn't ensure the content of students' inference while they helped students perform abductive reasoning and guided their use of specific thinking strategies. Students had found reasoning rules to explain the 01: served facts from their wrong prior knowledge. Therefore, during a geological field excursion, teachers need to provide students with proper background knowledge and information in order that students can reason rues for persuasive abductive inference, and construe the geological features of the field trip area by the establishment of appropriate hypotheses.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.35-47
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• 2005

This paper is to review a literature concerning Bus Transit Route Network Design(BTRNDP), to describe a future study direction for a systematic application for the BTRNDP. Since a bus transit uses a fixed route, schedule, stop, therefore an approach methodology is different from that of auto network design problem. An approach methodology for BTRNDP is classified by 8 categories: manual & guideline, market analysis, system analytic model. heuristic model. hybrid model. experienced-based model. simulation-based model. mathematical optimization model. In most previous BTRNDP, objective function is to minimize user and operator costs, and constraints on the total operator cost, fleet size and service frequency are common to several previous approach. Transit trip assignment mostly use multi-path trip assignment. Since the search for optimal solution from a large search space of BTRNDP made up by all possible solutions, the mixed combinatorial problem are usually NP-hard. Therefore, previous researches for the BTRNDP use a sequential design process, which is composed of several design steps as follows: the generation of a candidate route set, the route analysis and evaluation process, the selection process of a optimal route set Future study will focus on a development of detailed OD trip table based on bus stop, systematic transit route network evaluation model. updated transit trip assignment technique and advanced solution search algorithm for BTRNDP.