• Journal of Power Electronics
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• 제11권6호
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• pp.914-921
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• 2011

Commencing with incandescent light bulbs, every load today creates harmonics. Unfortunately, these loads vary with respect to their amount of harmonic content and their response to problems caused by harmonics. The prevalent difficulties with harmonics are voltage and current waveform distortions. In addition, Electronic equipment like computers, battery chargers, electronic ballasts, variable frequency drives, and switching mode power supplies generate perilous amounts of harmonics. Issues related to harmonics are of a greater concern to engineers and building designers because they do more than just distort voltage waveforms, they can overheat the building wiring, cause nuisance tripping, overheat transformer units, and cause random end-user equipment failures. Thus power quality is becoming more and more serious with each passing day. As a result, active power filters (APFs) have gained a lot of attention due to their excellent harmonic compensation. However, the performance of the active filters seems to have contradictions with different control techniques. The main objective of this paper is to analyze shunt active filters with fuzzy and pi controllers. To carry out this analysis, active and reactive current methods ($i_d-i_q$) are considered. Extensive simulations were carried out. The simulations were performed under balance, unbalanced and non sinusoidal conditions. The results validate the dynamic behavior of fuzzy logic controllers over PI controllers.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.612-617
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• 2007

Water meter frost in winter is a nuisance to the water administration and citizen as well. It causes stop of water supply, possibility of accident due to leakage freezing, and additional official work to change frost water meters. This study was carried out to give some basic information of water meter frost condition, to verify the effect of frost protection devices such as lagging vinyl cover, electric heater, and meter pit using subterranean heat. Nearly half of the number of the water meter frost happens in old apartment house with outer corridor, and temperature of the meter box was measured in that kind of apartment house, comparing with atmosphere temperature. The capability of three kinds of lagging vinyl cover was investigated by measuring the inside temperature of the insulated box. Also the capability of existing meter pits and new meter pits using subterranean heat was compared by measuring the inside temperature of the pits. One of the result is that the inside temperature of meter pits using subterranean heat was higher than that of the existing ones, and deeper pit causes higher inside temperature in case of using subterranean heat.

• 전력전자학회논문지
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• 제13권1호
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• pp.15-21
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• 2008

공장전기설비에서 개인용 컴퓨터, 정류기, 전기로와 시험장치 등의 비선형 부하 사용 증가에 따른 고조파 발생으로 누전차단기가 오동작하거나 불필요 동작을 하고 있다. 따라서 공장전기설비의 안전관리자를 대상으로 누전차단기의 오동작 상태에 대한 조사를 실시하였다. 또한 누전차단기가 오동작하거나 불필요 동작을 하고 있다는 수용가에서 전압, 전류, 고조파와 불평형 등 전력품질을 측정하고 분석하였다. 본 연구결과는 왜형된 전류파형으로 누전차단기의 트립특성 시험과 누전차단기 오동작 원인분석시 자료로 활용하고자 한다.

• Weed & Turfgrass Science
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• 제5권3호
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• pp.144-154
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• 2016

Goosegrass [Eleusine indica (L.) Gaertn] has been a nuisance to growers in Malaysia due to its increased resistance to commercial herbicides, rapid growth and dissemination, and interference with agricultural practices. In the course of developing an apt integrated management to control goosegrass, more information of this weed is needed. The aim of this study was to look into variations among the goosegrass ecotypes sampled throughout Malaysia from the aspects of genotype and phenotype. Sequence-related amplified polymorphism (SRAP) markers were employed in investigating the genetic diversity and relationships among the 18 goosegrass ecotypes. Consequently, 5 primer combinations amplified 13 fragments with the polymorphism rate of 69.23%. At 74% similarity, the ecotypes were clustered into 6 groups. Phenotypic variability of the goosegrass ecotypes was assessed by observing their morphology, growth and seed traits. Goosegrass ecotypes were sorted into 3 major groups at the genetic distance (DIST) of 0.37. Concurrences of the evaluated genetic distance, ecotypes with the closest and most distant relationships were assembled together in Group I which showed high variation even among ecotypes in the same group. Results obtained thus implied high molecular and morphological variations of the goosegrass ecotypes in Malaysia.

• Wind and Structures
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• 제11권1호
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• pp.51-70
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• 2008

CFD is applied to evaluate pedestrian wind comfort at outdoor platforms in a high-rise apartment building. Model validation is focused on generic building sub-configurations that are obtained by decomposition of the actual complex building geometry. The comfort study is performed during the design stage, which allows structural design changes to be made for wind comfort improvement. Preliminary simulations are performed to determine the effect of different design modifications. A full wind comfort assessment study is conducted for the final design. Structural remedial measures for this building, aimed at reducing pressure short-circuiting, appear to be successful in bringing the discomfort probability estimates down to acceptable levels. Finally, the importance of one of the main sources of uncertainty in this type of wind comfort studies is illustrated. It is shown that the uncertainty about the terrain roughness classification can strongly influence the outcome of wind comfort studies and can lead to wrong decisions. This problem is present to the same extent in both wind tunnel and CFD wind comfort studies when applying the same particular procedure for terrain relation contributions as used in this paper.

• 한국중재학회지:중재연구
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• 제32권3호
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• pp.3-27
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• 2022

Climate change is a man-made disaster that has become a major global concern today. With increasingly visible symptoms of climate change in recent years, it has become evident that climate action can no longer be dismissed as a mere matter of choice, but as a matter of survival for the human being. To address the impending climate change crisis in a collaborative and sustainable manner, the international community has been taking various measures including Kyoto protocol and the Paris Agreement. With respect to the private investor's project investment in line with international agreements on climate change, recently we have seen multiple legal judgments which clearly indicate the subject of judicial responsibility for investment in climate change related projects. However, in order to hold judicial responsibility occurring during the implementation of climate change related projects, a causal relationship between the responsible entities and clear responsibility must be demonstrated, and applicable institutional arrangements need to be arranged. It may be the right time for global community to consider shifting not only to human ethical obligations but also legal obligations. In this regard, concerned governments should consider legislating arbitration laws, regulations, and institutional arrangements in more specific and applicable manner.

• 상하수도학회지
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• 제18권4호
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• pp.480-485
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• 2004

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Nocardia amarae causing a nuisance foaming problem in activated sludge process. The identified signature peak was 19:1 alcohol as a reliable unique peak to N. amarae. Chemostat study revealed that the distribution and quantity of fatty acid peaks were dependent on the growth stage of Nocardia. The FAME results were similar for two relatively high dilution rates; however, the amounts of signature peaks extracted from the 4 and 6 day cultures were significantly higher. This dependence of signature peaks on the physiological state of the organism may be a useful information to assess the health of microbial populations in activated sludge. A laboratory scale batch foaming potential experiment provided a critical foaming level depending on Nocardia population. This critical Nocardia level determined in this study was in terms of either the threshold filament intersections number or the threshold signature FAME amount. The threshold peak area of signature FAME (19:1 alcohol) and corresponding filament counts were 430PA/mg VSS and $1.45{\times}10^6$ intersections/g VSS, respectively. The threshold signature FAME level could be effectively applied as a criterion for diagnosing foam occurrence in activated sludge system.

• ALGAE
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• 제29권4호
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• pp.249-265
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• 2014

As with land crops, cultivated algae are affected by various diseases ranging from large outbreaks of a disease to chronic epiphytes, which may downgrade the value of the final product. The recent development of intensive and dense mariculture practices has enabled some new diseases to spread much faster than before. A new disease is reported almost every year, and the impact of diseases is expected to increase with environmental change, such as global warming. We observed the incidence of diseases in two Pyropia sea farms in Korea from 2011 to 2014, and estimated the economic loss caused by each disease. Serious damage is caused by the oomycete pathogens, Pythium porphyrae and Olpidiopsis spp., which decreased the productivity of the Pyropia sea farms. In Seocheon sea farms, an outbreak of Olpidiopsis spp. disease resulted in approximately US $1.6 million in loss, representing approximately 24.5% of total sales during the 2012-2013 season. The damage caused by green-spot disease was almost as serious as oomycete diseases. An outbreak of green-spot disease in the Seocheon sea farms resulted in approximately US $1.1 million in loss, representing 10.7% of total sales in the 2013-2014 season in this area. However, the causative agent of green-spot disease is still not confirmed. "Diatom felt" is regarded as a minor nuisance that does not cause serious damage in Pyropia; however, our case study showed that the economic loss caused by "diatom felt" might be as serious as that of oomycete diseases. Bacteria and cyanobacteria are indigenous members of epiphytic microbial community on Pyropia blades, but can become opportunistic pathogens under suitable environmental conditions, especially when Pyropia suffers from other diseases. A regular acid wash of the Pyropia cultivation nets is the most common treatment for all of the above mentioned diseases, and represents approximately 30% of the total cost in Pyropia sea farming. However, the acid wash is ineffective for some diseases, especially for Olpidiopsis and bacterial diseases.

• 환경위생공학
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• 제10권1호
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• pp.45-65
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• 1995

Seasonal occurrences and dynamics on the freshwater algae were examined in the upstream of the Yongsan river system with the Kwangju service water area from 1993 to 1994. Three hundred and three taxi were totally collected and composed of 6 classes, 15 orders, 7 suborders, 31 families, 74 genera, 248 species, 48 varieties and 7 forma. Compositions in each algal class were divided in 136 taxi of Chlorophyceae(44.8% ), 109 taxi of Bacillariophyceae(36.0% ), 30 taxa of Cyanophyceae(10.1% ), 21 taxa of Euglenophyceae(6. 9% ),4 taxi of Chrysophyceae(1.3% ) and 3 taxa of Dinophyceae(1.0% ). The occurrence of taxa was a markedly decrease(-62) between summer and autumn, the critically increase(+43) between spring and summer. And also, it was indicated that the high frequency of taxa in summer, but the high standing biomass In winter in spite of low taxi. In general, it has much algal biomass in station 9 and 10, but low in station 4, 5 and 11, relatively. Through this survey, the major dominant taxa in algal biomass, Microcystis aeruginosa, Melosira varians, Synedra ulna and Navicula cryptocephala, they were all above 2.1×10$^{6}$ce11s/1, 13.2% of totals. There are about 10% of new emigrated taxa by season and they showed a remarkable succession. We may suggested that this system was well sustained for the habitat of freshwater algal community with low dominance and high diversity. Twenty three of nuisance algae including of Microcystis aeruginosa, Peridinium willei and Anabaena flos-aquae were distributed as if had low appearance. Of course, many of them were saprobiontic taxa, extraordinary growttung groups depend on organic loading in water system and also it was not showed severe algal blooming phenomenon.

• 유기물자원화
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• 제6권2호
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• pp.113-129
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• 1998

본 연구에서는 가정에서의 음식물찌꺼기 분리 수거 방안을 구체적으로 제시하는 것을 목적으로 실질적으로 분리 수거의 주체가 될 각 가정의 배출자들을 대상으로 이들의 분리 수거에 대한 의식과 성향을 조사하였다. 설문 응답자들의 음식물찌꺼기 보관/배출/수거 주기에 대한 의견을 종합하면 음식물찌꺼기로 인한 냄새 발생 등을 최소하기 위해서는 매일 음식물찌꺼기를 버려야 하지만 자주 버리는 것으로 인한 번거로움도 있으므로 집안에서 2-3일간의 음식물찌꺼기를 현행 종량제 봉투와는 크기가 다른 비닐 봉투 등 별도의 음식물찌꺼기 용기에 모아 두었다 집밖의 분리 수거통에 배출하면 수거하는 쪽에서는 매일 분리 수거통에 모아진 음식물찌꺼기를 수거해가는 것으로 요약된다. 그리고 이때 사용되는 보관 및 배출 용기는 크기를 이틀 발생분(1.87L, 약 2L) 또는 3일 발생분(2.8L, 약 3L)의 두가지로 제작하는 것이 타당한 것으로 분석되었다. 또한 음식물찌꺼기의 보관 및 배출에 적당한 용기는 비닐 봉투가 좋다는 의견이 가장 많았으며 비닐 봉투는 일회용이라는 점이 응답자들의 선택에 큰 영향을 미친 것으로 판단되었다. 봉투의 적정 가격에 대한 조사결과 전용 봉투의 가격은 싸게 하면 분리수거에 효과가 있겠으나 발생량 감소에는 그 효과가 미지수이며 비싸게 하면 발생량 감소에 효과있는 반면 분리수거에는 역효과가 일어나는 문제가 있는 것으로 나타났으며 대안으로서 봉투를 2가지 형태로 판매하는 방식이 제시되었다.