• 전력전자학회논문지
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• 제1권1호
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• pp.27-37
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• 1996

This paper proposes the control algorithm for maximum efficiency drive of PWM inverter - induction motor system with high dynamic performance. If the induction motor is driven under light load with rated magnetizing current, the Iron loss is excessively large compared with the codder loss which results in doer motor efficiency. Maximum efficiency drive of an induction motor can be achieved by controlling the magnetizing current to satisfy the optimal ratio that leads the total motor loss to be a minimum value at a given speed. The proposed control algorithm essentially uses vector control technique and adopts voltage decoupling control strategy to prevent the degradation of dynamic performance due to reduced magnetizing current. To verify the proposed method, digital simulations and experiments are carried out for a squirrel-cage induction motor with the rating of 2.2[kW].

• Membrane and Water Treatment
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• 제10권1호
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• pp.39-44
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• 2019

LID facilities do not consider environmental factors, and due to inappropriate vegetation planting causing degradation in efficiency due to plant damage and difficulty in maintenance. Therefore, in this study, assessment of impact environmental factor by seasonal variation of chlorophyll and growth of vegetation planted in LID technologies and change of pollutant reduction were conducted. In the case of B-SJ and B-RI, growth rate decreased after summer (August), and B-MG showed steady growth until autumn (September). Chlorophyll was found to increase during spring season while it decreased during autumn season. The chlorophyll concentration was found to affect the plant growth pattern. TN reduction efficiency was highest with greater than 80% efficiency in summer, and it was analyzed that plants were identified as the main factor affecting the seasonal reduction efficiency of TN. Also, temperature and relative humidity were analyzed to affect plant growth, activity and pollutant removal efficiency. Plant type and growth pattern are considered as factors to be considered in selection of appropriate plant types in LID technologies.

• 비파괴검사학회지
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• 제21권5호
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• pp.549-555
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• 2001

초음파법은 산업설비의 열화 정도나 결함을 평가하기 용이한 비파괴적 방법이다. 본 연구에서는 1Cr-1Mo-0.25V을 $630^{\circ}C$에서 등온열화처리하여 4개의 시편을 준비하였다. 이를 사용하여 초음파의 속도, 감쇠계수를 측정하여 재료의 열화를 평가하였으며, 배진동의 발생효률을 나타내는 비선형파라미터를 이용하여 재료의 열화정도를 평가하였다. 감쇠계수와 비선형파라미터는 열화가 진행될 수록 증가하였으며, 특히 1,820 시간 열화시편의 배진동 진폭은 원시시편의 배진동 진폭과 비교 시 20dB이상 증가하였나. 그러나 열화정도에 따른 속도의 변화는 거의 없는 것으로 나타났다. 본 연구결과에서 감쇠계수와 비선형파라미터는 재질 열화에 민감하게 반응하는 파라미터였으며, 재질 열화도를 평가하기에 적절한 파라미터인 것으로 사료된다.

• Environmental Engineering Research
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• 제25권4호
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• pp.571-578
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• 2020

In this work, a detailed study on the electrochemical degradation of an azo dye, Orange G is performed using a platinum electrode. Indeed, the influence of the dye concentration (50-150 mg/L), the pH of the medium and the density of the electric current is studied on the rate of discoloration, the rate of mineralization, the efficiency of the electric current and the energy consumption. The UV-visible spectra of OG plotted against the degradation time show the decrease of the intensity of the characteristic dye peaks. In an environment rich in chlorides, all peaks disappear after 15 min of degradation. However, the peaks at wavelengths of 200 and 290 nm appeared after one hour of treatment. In K₂SO₄, the eliminated percentages are respectively 46, 54 and 61% for wavelengths of 245, 330 and 480 nm. This suggests that the degradation mechanisms in K₂SO₄ and KCl environments are not the same. In the middle rich in chlorides, the eliminated percentage of OG did not seem to be affected by the concentrations increase. These results confirm the hypothesis that electrochemical oxidation process is very favorable for concentrated pollutants discharge.

• 한국태양에너지학회 논문집
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• 제30권6호
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• pp.16-21
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• 2010

It is well-known that Boron-doped Cz Si solar cells suffer light-induced degradation due to boron-oxygen defect which is responsible of a reduction in lifetime and hence efficiency. In this paper, we assume that PV solar cell has been connected with variable load to account the real operating condition and it shows different light-induced degradation of Si solar cell. To evaluate the effect of light-induced degradation for solar cell with various load, Single crystalline solar cells are connected with open and short circuits during light exposure. Isc-Voc curve evaluate light induced degradation of solar cells and the reason is explained as a change for serial resistance. From the results, Electrical characteristics of solar cells show better performance under short circuit conditions, after light exposure.

• 자원리싸이클링
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• 제18권6호
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• pp.10-17
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• 2009

과열 증기를 이용하여 생활 폐기물내 유기성 성분의 분해를 수행하고 폐기물의 특성 및 반응 시간이 폐기물의 분해율에 미치는 영향을 살펴보았다. 과열 증기를 이용한 분해 후 음식 및 폐지와 같은 생분해성 유기 성분은 쉽게 분해되었고 생분해성 유기 성분중 나무와 석유계 유기성 성분인 플라스틱, 금속과 같은 무기성 성분이 분해되지 않은 상태로 남아 쉽게 분리가 가능한 상태를 형성하였다. 입자의 크기 변화를 살펴본 결과 폐기물 내 생분해성 유기 성분이 적을수록 짧은 반응 시간에도 높은 입자 크기 감소를 보였으며 반응 시간이 60분 이상에서 최대 90% 이상의 입도 감소를 나타내었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1525-1526
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• 2013

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2010년도 춘계학술대회 논문집
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• pp.467-468
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• 2010

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2019년도 하계 학술발표초록집
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• pp.150-150
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• 2019

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권1호
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• pp.67-77
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• 2013

To improve the energy efficiency of conventional thermal treatment, soil remediation with microwave has been studied. In this study, the remediation efficiency of contaminated soil with semi-volatile organic contaminants were evaluated with microwave oven and several additives such as water, formic acid, iron powder, sodium hydroxide (NaOH) solution, and activated carbon. For the experiment, loamy sand and sandy loam collected from Imjin river flood plain were intentionally contaminated with hexachlorobenzene and phenanthrene, respectively. The contaminated soils were treated with microwave facility and the mass removals of organic contaminants from soils were evaluated. Among additives that were added to increase the remediation efficiency, activated carbon and NaOH solution were more effective than water, iron powder, and formic acid. When 10 g of hexachlorobenzene (142.4 mg/kg-soil) or phenanthrene (2,138.8 mg/kg-soil) contaminated soil that mixed with 0.5 g iron powder, 0.5 g activated carbon and 1 ml 6.25 M NaOH solution were treated with microwave for 3 minutes, more than 95% of contaminants were removed. The degradation of hexachlorobenzene during microwave treatments with additives was confirmed by the detection of pentachlorobenzene and tetrachlorobenzene. Naphthalene and phenol were also detected as degradation products of phenanthrene during microwave treatment with additives. The results showed that adding a suitable amount of additives for microwave treatments fairly increased the efficiency of removing semi-volatile soil organic contaminants.