• 대한토목학회논문집
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• 제36권1호
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• pp.1-11
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• 2016

현 국내 외의 설계기준들은 인공지진파에 의해 계산된 응답스펙트럼이 설계응답스펙트럼보다 작은 값의 수가 5개 이내일 경우 설계응답스펙트럼을 포괄 한다고 규정하고 있다. 현 설계의 문제점을 확인하기 위하여 설계기준을 만족하는 5개의 각기 다른 특성을 가진 인공지진파를 사용하여 교각에 대한 시간이력해석을 수행하고, 부재력을 정량적으로 평가하였다. 설계기준을 만족하는 인공지진파일지라도 구조물의 고유주기와 유사한 주기에서 계산된 응답스펙트럼이 설계응답스펙트럼보다 작을 경우 시간이력해석을 통한 내진의 안전성을 확보하지 못함을 확인하였다. 따라서 본 연구에서는 스펙트럼 가속도 값이 설계응답스펙트럼보다 모든 주기에서 큰 값을 갖는 인공지진파를 생성하는 기법을 이중 수정함수를 적용하여 제안하였다. 또한 제안된 기법에 의해 작성된 인공지진파가 국내 외의 기준들의 적합성을 만족하는지 검토하였다.

• 한국균학회지
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• 제24권4호통권79호
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• pp.255-264
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• 1996

호알카리성 진균 Cephalosporium sp. RYM-202가 생산하는 alkaline xylanase (CX-III)의 작용에 의해 xylan 기질로부터 생성되는 주요 가수분해 산물은 xylobiose와 중합도가 4이상인 xylooligosaccharides이었다. 이 효소는 xylobiose에 대한 분해능을 가지고 있지 않지만 xylotriose로부터는 xylobiose를, xlyotetraose로부터 xylobiose와 xylotriose를 주산물로 형성하였다. 이러한 결과들은 CX-III가 transglycosidase 활성을 소유하는 전형적인 endo-type xylanase임을 보여준다. N-bromosuccinimide에 의한 CX-III의 화학적 변환 실험결과 효소 1분자 당 2개의 tryptophan 잔기가 활성에 관여하는 것으로 나타났다. 그러나 iodoacetamide 및 diethylpyrocarbonate에 의한 효소활성의 저해효과는 나타나지 않음으로써 이 효소의 활성부위에 cysteine과 histidine 잔기가 필수적이지 않음이 확인되었다.

• 멤브레인
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• 제15권4호
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• pp.320-329
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• 2005

본 연구에서는 polyamide계 방향족 역삼투막이 염소 라디칼에 의해 polyamide 결합이 분해되어 염배제율이 급격히 감소되는 반면 수투과도는 증가되는 것을 확인하였다 이러한 polyamide 역삼투막의 염소에 대한 저항성을 향상시키기 위해서 불소기 함유 실란커플링제(fluorine-containing silane coupling agent, FSCA)를 이용하여 역삼투막 표면 개질 후 막에 대한 표면 특성 및 내염소성 변화를 관찰하였다. 그 결과 FSCA의 농도가 증가될수록 막 표면이 dense하게 도포되었으며, 원소분석을 통해 FSCA가 부착되어 있음을 확인하였다. 또한 개질한 막 표면 조도는 감소되고 표면의 소수성이 증가됨을 접촉각의 증가로 확인 할 수 있었다. 이 결과를 종합하여 볼 때, 역삼투막을 FSCA로 표면개질 함으로써 개질막의 염소에 대한 저항성을 향상시킬 수 있었다.

• 대한토목학회논문집
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• 제42권4호
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• pp.469-480
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• 2022

경사식방파제의 상치콘크리트 설계를 위해서는 수평파압이 산정되어야 하지만 불명확한 부분이 있다. Lee et al.은 상치콘크리트에 작용하는 수평파압 산정시 적용되고 있는 Goda 파압식의 수평파압보정계수를 제안하였다. Lee et al.의 제안식은 2차원 실험결과에 기반을 두고 있으며, 상치콘크리트 전면 피복재 어깨폭이 좁은 경우에 대한 것이다. 본 연구에서는 동일한 실험장비를 이용하여 피복재 어깨폭이 넓은 조건에 대한 수평파압 계측실험을 수행하였다. 노출부 구간의 경우에는 피복재 어깨폭의 증가에 따른 수평파압의 변화는 크지 않았으며, 보호부 구간의 경우에는 어깨폭이 증가함에 따라 수평파압이 감소하였다. 실험결과를 이용하여 피복재 어깨폭의 영향을 고려한 Goda 파압식의 파압보정계수를 제안하였다. 본 제안식은 테트라포드가 피복된 경사식방파제의 상치콘크리트 설계에 실무적으로 적용 가능할 것으로 기대된다.

• 폴리머
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• 제29권6호
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• pp.575-580
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• 2005

하이드록시 말단의 지방족 고차가지구조 폴리에스테르를 용융축합법을 이용하여 합성하였다. 말단의 하이드록시 그룹을 acryloyl chloride를 사용하여 비닐 말단으로 변환시켰으며, 말단변화에 따른 구조를 분석하고 분자량을 측정하였다. 비닐 말단의 지방족 고차가지구조 폴리에스테르는 점도가 높고 노란색의 투명한 액체이며, 하이드록시 말단의 지방족 고차가지구조 폴리에스테르에 비해 유리전이온도가 낮았다. 또한 비닐 말단으로 변형한 후에는 열안정성이 감소하였으며, 말단 작용기의 전환율 차이에 의해 불규칙적인 열분해거동을 보였다.

• Environmental Engineering Research
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• 제15권3호
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• pp.135-140
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• 2010

With the various urban characteristics of each city, the existing water demand prediction, which uses average liter per capita day, cannot be used to achieve an accurate prediction as it fails to consider several variables. Thus, this study considered social and industrial factors of 164 local cities, in addition to population and other directly influential factors, and used main substance and cluster analyses to develop a more efficient water demand prediction model that considers unique localities of each city. After clustering, a multiple regression model was developed that proved that the $R^2$ value of the inclusive multiple regression model was 0.59; whereas, those of Clusters A and B were 0.62 and 0.74, respectively. Thus, the multiple regression model was considered more reasonable and valid than the inclusive multiple regression model. In summary, the water demand prediction model using principal component and cluster analyses as the standards to classify localities has a better modification coefficient than that of the inclusive multiple regression model, which does not consider localities.

• International Journal of Industrial Entomology and Biomaterials
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• 제19권1호
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• pp.155-164
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• 2009

The most important factors in environment that influence the physiology of insects are temperature and humidity. Insects display a remarkable range of adaptations to changing environments and maintain their internal temperature (thermoregulation) and water content within tolerable limits, despite wide fluctuations in their surroundings. Adaptation is a complex and dynamic state that widely differs in species. Surviving under changing environment in insects depends on dispersal, habitat selection, habitat modification, relationship with ice and water, resistance to cold, diapause and developmental rate, sensitivity to environmental signals and syntheses of variety of cryoprotectant molecules. The mulberry silkworm (Bombyx mori) is very delicate and sensitive to environmental fluctuations and unable to survive naturally because of their domestication since ancient times. Thus, the adaptability to environmental conditions in the silkworm is quite different from those of wild insects. Temperature, humidity, air circulation, gases and photoperiod etc. shows a significant interaction in their effect on the physiology of silkworm depending upon the combination of factors and developmental stage affecting growth, development, productivity and quality of silk. An attempt has been made in this article to briefly discuss adaptation in insects with special emphasis on the role of environmental factors and their fluctuations and its significance in the physiology of mulberry silkworm, B. mori.

• 펄프종이기술
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• 제45권1호
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• pp.59-66
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• 2013

Fillers have been used for printing paper to improve printability, sheet formation and optical properties and to reduce production costs by replacing expensive wood pulps. However, an increased filler content will decrease paper strength because filler particles interfere with fiber-fiber bonding. In order to increase filler content without sacrificing too much paper strength in high filler content papers, the surface of precipitated calcium carbonate (PCC) has been modified by adsorbing anionic polyacrylamide and cationic starch in series. The adsorbed polymer layers would enhance interactions between the filler surface and the fiber surface, improving internal bonding. It was found that the modified PCC increased paper strength at a given filler content compared to the coventional method. Negligible differences in optical properties and formation of paper, filler and fines retention and drainage on the wire section were observed between the modified and the conventional PCC. However, the decreased bulk of paper was observed when the modified PCC was used.

• 환경정책연구
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• 제1권1호
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• pp.1-24
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• 2002

Due to the recent increase in greenhouse gases in atmosphere, world climate is rapidly changing and in turn, the earth ecosystem responds upon the climate changes. Comparing the ecosystem in the past, the present shapes of ecosystem is the result of the serious modification. Fishery resources in marine ecosystem, which usually occupy the upper trophic level, are also inevitable from such changes, because they always react to the natural environmental conditions. The northwestern Pacific is the most productive ocean in the world producing about 30% of world catch. From time to time, however, it has been notified that abundance, distribution and species composition of major fish species were altered by climate events. Furthermore, primary productivity of the ocean is not stable under the changing environments, so that carrying capacity of the ocean varies from one climate regime to another. Major climate events such as global warming, atmospheric circulation pattern, climate regime shift in the North Pacific, and El Nino event in the Pacific tropical waters were introduced in relation to fisheries aspects. The current status and future projection of fishery production was investigated, especially in the North Pacific including Korean waters. This new paradigm, ecosystem response to environmental variability, has become the main theme in marine ecology and fishery science, and the GLOBEC-type researches might provide a solution far cause-effect mechanism as well as prediction capability. Ecosystem management principles for multi-species should be adopted for better understanding and management of ecosystem.

• Environmental Engineering Research
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• 제20권3호
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• pp.205-211
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• 2015

Reduced forms of iron, such as zero-valent ion (ZVI) and ferrous ion (Fe[II]), can activate dissolved oxygen in water into reactive oxidants capable of oxidative water treatment. The corrosion of ZVI (or the oxidation of (Fe[II]) forms a hydrogen peroxide ($H_2O_2$) intermediate and the subsequent Fenton reaction generates reactive oxidants such as hydroxyl radical ($^{\bullet}OH$) and ferryl ion (Fe[IV]). However, the production of reactive oxidants is limited by multiple factors that restrict the electron transfer from iron to oxygen or that lead the reaction of $H_2O_2$ to undesired pathways. Several efforts have been made to enhance the production of reactive oxidants by iron-induced oxygen activation, such as the use of iron-chelating agents, electron-shuttles, and surface modification on ZVI. This article reviews the chemistry of oxygen activation by ZVI and Fe(II) and its application in oxidative degradation of organic contaminants. Also discussed are the issues which require further investigation to better understand the chemistry and develop practical environmental technologies.