• Journal of Power Electronics
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• v.16 no.3
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• pp.883-893
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• 2016

This paper presents a comprehensive analysis of the spurious turn-on phenomena in phase-shifted full-bridge (PSFB) converters. The conventional analysis of the spurious turn-on phenomenon does not establish in the PSFB converter as realizing zero voltage switching (ZVS). Firstly, a circuit model is proposed taking into account the parasitic capacitors and inductors of the transistors, as well as the parasitic elements of the power circuit loop. Second, an exhaustive investigation into the impact of all these parasitic elements on the spurious turn-on is conducted. It has been found that the spurious turn-on phenomenon is mainly attributed to the parasitic inductors of the power circuit loop, while the parasitic inductors of the transistors have a weak impact on this phenomenon. In addition, the operation principle of the PSFB converter makes the leading and lagging legs have distinguished differences with respect to the spurious turn-on problems. Design guidelines are given based on the theoretical analysis. Finally, detailed simulation and experimental results obtained with a 1.5 kW PSFB converter are given to validate proposed analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2000-2004
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• 2009

In general, for the condition monitoring of a power transformer using the UHF PD measuring technique, detection of any partial discharge, identifying the defect in the transformer and locating the insulation defect are necessary. In this paper one of the most frequent detects which can result in turn to turn fault in power transformer was examined for identifying the defect. In order to model the defect, as a discharge source, a partial discharge cell was used for experimental activity. Magnitude of electromagnetic wave signals and corresponding amount of apparent discharge were measured simultaneously against phase of applied voltage to the discharge cell. Frequency range and phase resolved partial discharge signals were measured and analyzed. The results will be contributed to build the defect database of power transformer and to decrease the occurrence of transformer faults.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.773-776
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• 1993

The thyristor turn-off model plays an important part in the design of thyristor snubber circuit. However, it is difficult to determine the thyristor turn-off characteristics. In this paper two methods to establish the simple thyristor turn-off model are proposed based on the reverse recovery characteristics given in the data sheets. Using the simple thyristor turn-off model, the optimum thyristor snubber circuit design procedures are presented considering maximum voltage spike, maximum reverse dv/dt, and turn-off loss.

• Journal of the military operations research society of Korea
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• v.25 no.2
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• pp.73-83
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• 1999

In this paper, we consider the shortest path network problem with fixed charges. A turn penalty algorithm for the shortest path problem with fixed charges or turn penalties is presented, which is using the next node comparison method. The algorithm described here is designed to determine the shortest route in the shortest path network problem including turn penalties. Additionally, the way to simplify the computation for the shortest path problem with turn penalties was pursued.

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.143-148
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• 2004

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.223-228
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• 1999

• Journal of Korean Society of Transportation
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• v.19 no.4
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• pp.73-84
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• 2001

Korean Highway Capacity Manual applies 7 adjustment factors to estimate saturation flows at signalized intersections. Among the adjustment factors, the right-turn adjustment factor uses equation hard to understand and requires complicated computing process comparing other adjustment factors. Thus. this study was conducted in order to suggest a new technique of estimating the right-turn adjustment factor which is easy to understand and simple to computer by having reasonable degree of accuracy. In this study the right-turn saturation flow ratios which are important in estimating the factor are suggested and the equation to estimate the volume of right-turn on red signal(RTOR) is developed based on observed data. The right-turn saturation flow rates can be estimated according to turning radius and number of lanes of crossing road dividing right-turn lanes into canalized and uncanalized lanes. The RTOR volume is estimated using the proportion of the time during which RTOR is possible to the whole time of red signal according to the through traffic volume per lane of the approach at signalized intersections. The technique of estimating the right-turn adjustment factor suggested in this study, which follows the HCM2000 of U.S. in principal, first judges the right-turn lane to be used exclusively for right-turn or not by employing the RTOR factor and the judging equation developed in this study. Next, if the right-turn lane is not exclusive right-turn lane, the shared right-turn lane is classified into single lane approach or multi lane approach. Thus, a total of three methods of estimating the right-turn adjustment factor to the three cases are suggested in this study.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.3
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• pp.12-19
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• 2010

In road network, especially in urban area, inefficiency of travel time is caused by signal control and turn maneuver at intersection and this inefficiency has substantial effects on travel time. When searching for the shortest path, this inefficiency which is caused by turn maneuver must be considered. Therefore, travel time, vehicle volume and delay for each link were calculated by using simulation package, PARAMICS V5.2 for adaptation of turn penalty at 16 intersections of Gangnam-gu. Turn penalty was calculated respectively for each intersection. Within the same intersection, turn penalty differs by each approaching road and turn direction so the delay was calculated for each approaching road and turn direction. Shortest path dealing with 16 intersections searched by Dijkstra algorithm using travel time as cost, considering random turn penalty, and algorithm considering calculated turn penalty was compared and analyzed. The result shows that by considering turn penalty searching the shortest path can decrease the travel time can be decreased. Also, searching the shortest path which considers turn penalty can represent reality appropriately and the shortest path considering turn penalty can be utilized as an alternative.

• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.201-207
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• 2014

This study investigated the center of mass and lower extremity kinematic patterns between carved and basic paralell turn during alpine skiing. Six experienced skiers (age: $20.67{\pm}4.72yrs$, body mass: $72.67{\pm}7.15kg$, height: $171.00{\pm}5.51cm$) participated in this study. Each skier were asked to perform carved and basic paralell turn on a $22.95^{\circ}$ groomed slope. Each turn was divided into the initiation phase, steering phase 1 and 2. The results of this study show that the carved turn spent significantly less running time than basic paralell turn at all three phases (p<.05). Also vertical displacement of the center of mass was significantly greater in carved turn at all three phases, whereas inward leaning angle of the center of mass was significantly greater in carved turn at the steering phase 1 and 2 (p<.05). Bilateral knee and hip joint angle were significantly greater in basic paralell turn at the initiation phase and the steering phase 2 (p<.05). On the other hand, left knee and hip joint angle were significantly greater in basic paralell turn at the steering phase 1 (p<.05). In order to perform successful carved turn, we suggest that skiers should coordinate bilateral knee and hip joint angles to adjust the center of mass, depending on three ski turn phases.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.1-18
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• 2019

A short-turn bus is a bus that is operated within a subsection of an existing bus line. Previous studies regarding short-turn buses decided optimal turn-back points for a single bus line rather than a bus network. Also, in-vehicle crowding which has a significant impact on transit convenience was rarely considered. Therefore, this study aimed to develop a methodology to set priorities for the introduction of short-turn buses of bus lines and sections, considering crowding. To achieve this objective, we calculated occupancies and crowding alleviation benefits of existing bus lines overlapping a new short-turn route based on transit card data, before and after the introduction of short-turn strategy. Also, operator and social costs caused by the introduction of short-turn buses were calculated. Those procedures were iterated over bus lines and sections to operate a short-turn service, and a section whose benefit-to-cost ratio (B/C) is the largest in a line was selected to operate a short-turn service in the line. After, priorities of bus lines to introduce short-turn services could be determined based on B/C values, and the optimum total fleet size could be determined when a short-turn strategy is applied in multiple lines.