• 한국대기환경학회지
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• 제14권5호
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• pp.443-454
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• 1998

Pt-V catalytic converter was installed on a heavy duty diesel engine and the characteristics of the emission reduction were tested using a engine dynamometer at various operating conditions. The emission reduction performance of Pt-V catalyst was also compared with that of a commercialized Pt catalyst currently being used in some of the heavy duty diesel engines in advanced countries. The effects of Pt-V and Pt catalysts on regulated and unregulated emissions were investigated using a 0.05 weight percent sulfur content fuel with an engine dynamometer Experiments for gaseous emissions (CO, HC and aldehyde) as well as particulate emissions (TPM, SOF and sulfate) have been conducted at several operating conditions such as T-7 mode, D-13 mode and S-13 mode before and after installing the Pt-V and Pt catalysts in the exhaust system. The emission reduction performance of Pt catalyst with respect to CO, HC, SOF, PAHs and aldehyde was found to be a little higher than that of Pt-V catalyst, but the Pt catalyst showed innate disadvantage of causing an increase of PM due to the sulfate formation via high SO2 conversion at high exhaust temperature, especially above 45$0^{\circ}C$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.145-147
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• 2005

This paper presents a methodology for satisfying the thermal comfort of Indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. KEPCO(Korea Electric Power Corporation) use the fixed duty cycle control method regardless of the indoor thermal environment. This method has disadvantages that energy saying depends on the set-point value of the Air-Conditioner and DLC has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. A variable duty cycle estimates the PMV(Predict Mean Vote) at the next step with a predicted temperature and humidity coming from the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. The proposed methodology uses the historical real data of Sep. 7th, 2001 from a classroom in seoul to verify the effectiveness of the variable duty cycle method comparing with fixed duty cycle. The result shows that the variable duty cycle reduces the peak demand to 2.6times more than fixed duty cycle and increases the load control ratio by 8% more. Based on the variable duty cycle control algorithm, the effectiveness of DLC is much more improved as compared with the fixed duty cycle.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.270-273
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• 2000

A new phase shift PWM parallel-input/series-output modularized dual converter is proposed in this paper. This converter is operated with a fixed duty ratio and its output voltage is regulated by phase shift between each module. Since the operating duty ratio of each module is fixed it is sufficient to implement a simple open loop drive circuitry for each module and the cost of total system can be much reduced. The operation of the converter is analyzed in this paper and verified by computer simulation.

• 한국정밀공학회지
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• 제19권8호
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• pp.161-171
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• 2002

This paper presents a linear motor, which generates large thrust with a low operating rate. In industrial fields there is a need for actuators that work with a low duty cycle but generate large thrusts. An example of such a case is provided by the actuators for ejector mechanisms in electric injection molding machines. The ordinary LSM (linear synchronous motor) is unsuitable for this large-thrust and low-operating-rate usage, because of its large size and high cost. This paper contains experimental results on linear motors that can generate large thrusts for a short time, and which can be cheaply produced. The described linear motor could be contained space of $250mm \times250mm\times 250mm$ and generate a maximum thrust of about 20000 N at a current of 250 A.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.194-197
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• 2001

Traction motors driven by high speed switching inverters is demanded higher operating temperature, severe duty cycles, higher starting current, frequent voltage transients and finally severe environmental exposure. For applications to inverter duty, traction motors needs a special insulation system, which has characteristics of increased bond strength, lower operating temperature and higher turn-to-turn insulation. In this paper, design considerations and manufacturing procedure of 200 Class insulation system with polyimde(Kapton) main insulation and silicone resin VPI process on the traction motor for EMU will be reviewed. And performance test and long life evaluation test which prove stability and long life evaluation test which prove stability and reliability of insulation system for traction motor will be introduced.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.21-24
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• 2000

Traction motors driven by several type inverters have been subjected to increasing demands for higher operating temperature, more demands for duty cycles, higher starting current, frequent voltage transients and finally severe environmental exposure. For applications to inverter duty, traction motors needs a special insulation system, which has characteristics of increased bond strength, lower operating temperature and higher turn-to-tum insulation. Also it needs major contributors to insulation life and reliability of motors, which more considered by temperature, voltage, frequency, rise time, pulse configuration, wire thickness and insulation materials. In this paper, to evaluate of reliability and expected life, it is analyzed the several stresses and their degradation mechanism on insulation system of AC traction motor.

• 전기학회논문지
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• 제66권11호
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• pp.1575-1583
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• 2017

With the development of DC distribution, DC circuit breaker is required to ensure the stability of the DC grid. Unlike a mechanical circuit breaker that blocks after several tens of milliseconds, a DC SSCB(Solid-State Circuit Breaker) can break the fault well within 1 [ms], so it can prevent the damage of accident. However, the previous DC SSCB requires a lot of switching elements for charging commutation capacitors, and the control is complicated. Therefore, this paper proposes a new DC SSCB suitable for DC grid. The proposed DC SSCB is simple to control for charging commutation capacitors, and it can perform the rapid breaking and operating duty of reclosing and rebreaking. The proposed DC SSCB was designed to 380 [V] and 5 [kW] class which is suitable for residential DC distribution, and the operating characteristics of the proposed DC SSCB were verified by simulations and experiments. It is anticipated that the proposed DC SSCB may be utilized to design and realize DC grid system.

• 한국전기전자재료학회논문지
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• 제22권8호
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• pp.659-664
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• 2009

This paper describes lightning impulse operating duty performance and temperature dependence of series gap type for transmission line arresters. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by lightning impulse current. In the discharge withstand test, total energy applied to the ZnO arrester each time is 4/10 ${\mu}s$, 30 kA. and in the operating duty test, the arrester has passed the test if thermal stability is achieved, if the residual voltage measured before and after the test is not changed by more than 5 %, and after the test reveals no evidence of puncture, flashover or cracking of the ZnO block. As a results, the residual voltage was in the range of 17.2${\sim}$20.3 kV and ZnO block bear up against at 2 shot of series impulse current of 30 kA. Also it was so excellent that the mechanical destruction does not occur at the 2 groups of 5 impulses current of 2/20 ${\mu}s$ 10 kA. According to the tests, it is thought that the ZnO arrester shows good stability with impulse current test. and it was found that the ambient temperature is increased resistive leakage current was increased in the range 47.3${\sim}$167.4 ${\mu}A$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1433-1438
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• 2007

Characteristics of a phase change type micro actuator have been studied. The micro actuator has been designed for a micro-pump in an active direct methanol fuel cell(DMFC), consisting of an actuating chamber, a membrane, an electric heater, and a sensor of resistance temperature detector (RTD). In the present study, researches have been focused on the response of the actuator to control algorithm of the heater. The experiments demonstrated that the displacement of the membrane increase with temperature variation which is a function of applied voltage, duty ratio, and operating frequency of heating. The results also showed that operation of the actuator with high voltage at small duty of heating is more efficient than the same power consumption of heating with low voltage at large duty.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.827-831
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• 1997

Conductive veramic matrix composite(CMC) workpiece of TiC 33%/Al /sab 2/O /sab 3/ 66% Y /sab 2/ O /sab 3/ was machined by die sinking electrical discharge machining(EDM) according to different pulse duration and suty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operating conditions. The surface morphology was evaluated by surface roughness values and scanning electron microscopy(SEM) research. The more MRR was obtained according to increase pulse duration and duty factor. Also the maximum surface roughness(Rmax) of EDMed surface was slightly changed with increased pulse duration and duty factor. The SEM photographs of EDMed surface showed wide recast wide recast distribution region of melting materials in purse duration 0.130(ms) than 0.048(ms).