• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.443-445
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• 2002

In this paper, we present a novel efficient semaphore implementation scheme which diminishes completion time of high priority tasks and improves reliability of a system. The real-time system is constrained to complete their tasks in time. Especially, the task of a hard real-time system must meet its deadline under unfavorable conditions. In this paper, the number and sort of the locked semaphores, when an event occurred, decide whether the context switch should occur or not, so higher priority tasks diminish in their completion time. The experimental results show that the proposed method gives performance improvements in finish time of high priority tasks of about 11% over the Zuberi.

• 대한전자공학회논문지
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• 제12권1호
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• pp.12-17
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• 1975

광대역의 계수율을 선택 스윗치 없이 계측하기 위한 대수계수율회로에 관한 해석을 하였고 그에 의한 다데케이드 계수율회로의 구성방법과 실험결과를 지시하였다. 이 대수계수율회로는 주기적인 입력 펄스 뿐만 아니라, Poisson분포를 갖는 random한 펄스에 대하여도 대수적인 응답특성을 가지며 계수율 1pps로 부터 $10^5$pps까지 데케이드의 영역에 걸쳐 좋은 대수특성을 가지며 또한 낮은 영역과 높은 영역에서의 특성저하의 원인을 규명하여 양단에서의 특성을 효과적으로 보상하였다.

• Design & Manufacturing
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• 제2권5호
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• pp.30-33
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• 2008

Injection Molding is the most effective process for mass production of plastic parts. The injection molding process is composed with several steps such as Filling, Packing, Holding, Cooling, Ejecting. Among them, filling and packing process should be considered carefully to improve accuracy of dimension, surface quality of plastic parts. Usually the quality above-mentioned is managed with weight of part after molding on the field. In this paper, a series of experiment for molding automotive front bumper was conducted with cavitity temperature sensor to optimize switch-over time(V-P switching), hot runner vale gate sequence time during filling and packing step for the purpose of uniform quality, weight at every molding. As a result, it was found that it is effective method to use temperature sensor in injection molding for quality control of plastic molding.

• 정보통신설비학회논문지
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• 제6권3호
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• pp.1-7
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• 2007

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide efficient utilization in optical networks. Under several legacy schemes, a switch drops the burst with the shortest time regardless of its traversed hop count. As a result, a dropped burst that have been traversed many hops might cause increased bandwidth waste compared to one that has traversed a few hops. To improve this problem, we propose the Just Enough Time (JET) with a hop counting scheme which can reduce the wasted bandwidth by prioritizing the burst traversed many hops over others. From the simulation result, it is preyed, we show that the proposed scheme has advantages against legacy schemes in terms of the burst blocking probability and the link utilization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.73-77
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• 1990

In this paper we describe the solid-state ac-circuit breaker which has the characteristic of both a half cycle circuit breaker and a current limiting circuit breaker. This circuit breaker has a current limiting resistor in order to surprises the fault current to a certain level and discharge the energe included in circuit inductor. We explain the effect of circuit parameter on transient phenomena of switch device by using EMTP and finally design the control circuit consisted synchronous closing circuit, over- current detecting circuit and sensing circuit of rate of rise of fault current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.45-48
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• 1997

The low frequency pulsed MIG welding process of new current waveform control to switch over unit pulse conditions (pulse current, pulse duration) in the fixed cycle was developed and its effect were investigated for aluminium and its alloy. By using this new welding process, the bead appearance having clear ripple pattern, such as TIG welding bead can be obtained and the gap tolerance of lap and butt welding joint can be expanded.

• The Korean Journal of Ecology
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• 제15권4호
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• pp.345-354
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• 1992

Allocation patterns of energy and mineral elements were investigated with phaseolus multiflorus grown in the environmental gradients. The result showed different energy allocation patterns according to relative light intensities and nutrients. The optimal switching time of energy allocation from vegetative to resproductive growth was delated as decreasing relative light intensity. The switch of the shift to reproduction was timed earlier in phosphorus treatment and delayed in nitrogen treatment. Analyzing the mineral elements to various organs, patterns of energy allocation were different from those of mineral allocation. There was no significant difference for allocation patterns in relative light intensity gradients. it was shown that n and p were distributed over the reproductive organs, k mainly in stems, ca in leaves and na in roots. mg was evenly distributed in each organs.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권7호
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• pp.367-372
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• 2006

A novel coil gun type actuator has been proposed and tested for its possibility as an actuator for a high voltage circuit breaker by experimental method. The 20kJ capacitor bank with the electrolytic condensers was charged up to 500V and discharged to a couple of 100 turn coils connected with parallel through a thyristor switch. The repulsive force between coil and the actuator made by copper conductor of 20kg reached up to 23,000 N, and over 800J of energy was transferred to the kinetic energy of the conductor. The experimental results showed that the coil gun type actuator has a good possibility for the high voltage circuit breaker.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.305-308
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• 2000

A technique to suppress the low frequency ripple voltage of the DC output in three phase buck diode rectifiers is presented in this paper. The proposed pulse frequency modulation methods and duty ratio modulation methods are employed to regulate the output voltage of the buck diode rectifiers and guarantee zero-current -switching(ZCS) of the switch over the wide load range The proposed control methods used in this paper provide generally good performance such as low THD of the input line current and unity power factor. IN addition control methods can be effectively used to suppress the low frequency ripple voltage appeared in the dc output voltage. The harmonic injection technique illustrates its validity and effectiveness through the simulations.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1122-1130
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• 2013

This paper proposes a new design for quick battery charger systems for electric vehicles that consists of a three-phase inverter and a full-bridge converter which use the phase-shift method. The 3-phase inverter controls the input and DC-link voltage by use of a current controller and a voltage controller. The full-bridge converter transfers the DC-link voltage to a fixed output voltage. Designs for the output-side converter and controller for improved performance are proposed in this paper. Design schemes for the filter and controller of an input-side inverter are also presented. Furthermore, the paper proposes a compensation method for the offset current that is caused by switch failure and circuit problems. Simulations and experiments have been performed on a 50kW-battery charger system that is suitable for vehicles. The presented results verify the validity of the proposed method and the superiority of the system over conventional methods.