• Corrosion Science and Technology
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• 제10권6호
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• pp.218-224
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• 2011

The fresh water and sea water in present ships is used as cooling water for marine engine. Therefore, corrosion damage in seawater system is frequently occurred. In particular, in the impeller of pump, the performance and material span due to the corrosion and cavitation erosion has adverse effects. Most of the pump impellers in vessels are used Cu-Al alloy. Cu-Al alloy which having the excellent mechanical properties and corrosion resistance is widely used in marine environments. However, despite the excellent characteristics, the periodic replacement parts due to the cavitation damage in seawater is vulnerable to economic viewpoint. In this study, Cu-Al alloy used with impeller for centrifugal pump were conducted various experiments to evaluate its characteristics in seawater and fresh water solutions. As an electrochemical result, the dynamic conditions that exposed to the cavitation environment presented high corrosion current density with collapse of the cavity compared with the static conditions. Cavitation test results, the weightloss and weightloss rate in fresh water are observed more than those of seawater.

• 한국농공학회논문집
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• 제54권5호
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• pp.25-34
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• 2012

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to cement mortar by forming expansive hydration products due to the reaction between cement hydration products and acid and sulfate ions. In this study, the effect of fly ash and blast furnace slag on the bond performances of structural synthetic fiber in latex modified cement mortar under sulfate environments. Fly ash and blast furnace slag contents ranging from 0 % to 20 % are used in the mix proportions. The latex modified cement mortar specimens were immersed in fresh water, 8 % sodium sulfate ($Na_2SO_4$) solutions for 28 and 50 days, respectively. Pullout tests are conducted to measure the bond performance of structural synthetic fiber from latex modified cement mortar after sulfate environments exposure. Test results are found that the incorporation of fly ash and blast furnace slag can effectively enhance the PVA fiber-latex modified cement mortar interfacial bond properties (bond behavior, bond strength and interface toughness) after sulfate environments exposure. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results under sulfate environments.

• 한국환경과학회지
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• 제11권9호
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• pp.881-895
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• 2002

Sediments and river waters form the channel of Hwasun-cheon were studied in sedimentological size and geochemical analyses of metallic elements for the purposes of identification of depositional environments and geochemical characteristics. The sizes of sediments are assigned to pebble to coarse sand in mean size and polymodal in distribution. And the sediments are poorly to very poorly sorted and positively skewed. According to the grain size distributions of the sediments, the Hwasun-cheon belongs to gravel-bed river on the basis of the grain size distribution of the sediments. The behaviors of metallic elements in the sediments mainly depend on not grain size distribution but the geology connected with geomorphological reliefs near the stream. Contamination indices(CI) of Zn, Cu and Pb are 2.83 to 6.96 with average 4.31 in the sediments. Hwasun-cheon is assigned to general stream type in accordance with water quality of physical factors and chemical characteristics by Piper's diagram. Though meaningful values of BOD, T-N, T-P were locally depicted near Masan-ri, Hwasun-eup and Jiseok-cheon areas, artificial metal concentration do not represent in the most area of the stream. Sediments and river water are considered that the relatively more or less high metallic contents in the stream are originated from coal mine and urban area.

• 한국전자통신학회논문지
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• 제10권9호
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• pp.965-972
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• 2015

본 논문은 송지호 재첩서식의 적지선정을 위한 방법에 대해 살펴본다. 수차례에 걸쳐 현장탐사와 시료채취를 통한 수질검사로 수집된 자료를 지리정보시스템(GIS)을 이용하여 분석하였다. 송지호의 재첩 서식환경의 특성을 파악하기 위해 수온, 염분, 용존산소 농도, PO4-P 농도를 활용하였다. 본 연구는 서식환경이 유사한 여타 석호 등에서 재첩 증식의 기초자료로 활용할 수 있을 것으로 기대된다.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.221-229
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• 2006

The purpose of this study is to analyze the characteristics of healing environments of the wards in women's hospitals. A evaluation checklist of the healing environment was applied to seven women's hospitals that have constructed or remodeled since 2000. The findings indicate that the comfort was well considered in most spaces, while the privacy and the nature-friendliness were insufficient. The lacks of balconies, terraces, landscapes, and water spaces for the nature-friendliness were also problematic. Among the patients' room, corridor, and patients' lounge, the lounge was the most negative in terms of healing environments. In order to improve the patients' privacy, soundproofing materials and buffer zones in the lounge should be considered. The future study needs to develop advanced survey and interview methodologies in order to support the relevant results.

• 한국철도학회논문집
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• 제4권2호
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• pp.62-70
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• 2001

Pure copper, Cu-1.1wt%Cd and ACSR(Aluminum Conductor Steel Reinforced) have been used as catenary materials of the electric railway system. Since these materials may be exposed to the corrosive environments like polluted air, acid rain and sea water, it is important to investigate the corrosion rates in various corrosive environments. The aqueous corrosion characteristics of catenary materials in aerated acid, neutral and alkali solutions were studied by using immersion corrosion tests, electrochemical measurements and analytical techniques. In order to examine corrosion characteristics according to the dissolved oxygen content, pH, chloride ion concentration ion, and the addition of Cd to Cu, a series of tests such as potentiodynamic polarization, a.c impedance spectroscopy and galvanic corrosion tests were carried out with these materials. Results showed that the addition of Cd to Cu and chloride ion in the solution have an adverse effects on the resistance to corrosion. Additionally, Galvanic currents between Al and steel wires of ACSR were confirmed by using ZRA(zero resistance ammeter) method.

• 한국해양환경ㆍ에너지학회지
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• 제11권3호
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• pp.113-123
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• 2008

유독성 Cochlodinium polykrikoides 적조의 최초발생해역으로 알려져 있는 나로도 주변 해역의 해양환경적 특징을 조사하기 위해서 1992년부터 2007년까지 국립수산과학원이 실시한 해양환경측정망 자료 및 적조정보자료와 고흥지방의 기후자료 등을 분석하였다. Cochlodinium polykrikoides 적조는 8월에 나로도 주변 해역에서 최초로 발생한 경우가 가장 많았고, 그 발생시기는 해마다 빨라지고 있는 경향을 보였다. 또한 나로도 주변 해역에서의 표층 염분도 계속 증가하는 추세를 보여, Cochlodinium polykrikoides 적조 발생시기의 빨라짐과의 어떤 관련성을 시사하였다. 한편 나로도 주변 해역에서 Cochlodinium polykrikoides 적조가 최초로 발생할 때는 동일한 시기의 가막만 또는 진해만 해역에 비해 상대적으로 일사량은 많았고 강수량은 적었다. 8월의 나로도 주변 해역의 평균 수온 및 염분은 동일한 시기의 가막만 및 진해만에 비하여 평균 수온은 $0.2{\sim}0.6^{\circ}C$, 염분은 $1.84{\sim}3.91psu$ 각각 더 높았으며, 두 해역에 비해 상대적으로 고온, 고염을 나타내었다. 또한 나로도 주변 해역은 부영양화 해역으로 알려진 진해만에 비해서는 영양염이나 식물플랑크톤의 농도가 현저히 낮았으나, 전체적인 수질환경은 가막만과 크게 다르지 않은 것으로 판단되었다. 주성분 분석결과, 나로도 주변 해역에서 최초로 발생하는 Cochlodinium polykrikoides 적조 요인으로서는 기상인자와 물리적 환경인자인 일사량과 수온이 가장 중요하며, 부차적으로 수질요소인 COD와 용존산소의 농도가 여기에 관여하고 있음을 보여주었다. 태풍 또한 Cochlodinium polykrikoides 적조 발생에 있어 중요한 요인 중의 하나로 생각되었다.

• 한국미생물·생명공학회지
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• 제7권3호
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• pp.175-179
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• 1979

참굴의 성수기인 1978년 12월, 1979년 1월 및 2월에 걸쳐 주산지인 고성만과 돌산의 참굴과 그 참굴이 서식한 해수 및 이토 등을 시료로하여 세균의 오염도와 그 동정을 한 결과 다음과 같이 요약된다. 1. 생균수의 범위는 참굴, 이토, 해수에서 각각 $10^4$~$10^{6}$, $10^{5}$ ~$10^{6}$, $10^3$~$10^4$ 이었다. 2. 분리균 382균주 중에서 Vibrio속이 45.3%로 우점종을 이루었고, Pseudomonas속이 16.7%, Moraxella속이 11.5%, Flavobacterium-cytophaga속이 8.9%로 이들 4균속은 82.4% 나되어 참굴 및 그 서식한 해수 및 이토중에 중요한 세균 Flora 로 나타났다. 3. Vibrio속으로 동정된 173균주 중 참굴에서 56.3%, 이토에서 54.0%, 해수에서 25.8%로 해수 중의 분포도가 현저히 낮게 검출되었다. 4. Pseudomonas속 가운데에서 Pseudomonas I 균형은 해수에만 검출되었고 Pseudomonas III/IV 균형도 해수에서 많이 출현하였으며 그 외 균속은 큰 변동이 보이지 않았다.

• Tribology and Lubricants
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• 제35권6호
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• pp.396-402
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• 2019

Materials made from plastics are increasingly utilized in constructing greenhouses and setting up shield structures. Polyester fabrics have a wide range of use in horticulture and other fields of agriculture. They are utilized as a greenhouse cover and also help in combating intense climate variation in the field. Over time, these fabrics may experience friction against other surfaces. Owing to this, the surface framework of the material degenerates. This study examines the frictional characteristics of aluminized polyester fabric in both dry- and water-lubricated environments under changing applied loads and sliding speeds. Friction experiments are performed at room temperature by employing a pin on a disk. The experiments reveal that the friction coefficient decreases with increase in applied load in both dry sliding and water-lubricated environment. However, the friction coefficient decreases more under the water-lubricated setting than in the dry state. At the maximum applied load, the highest friction coefficient is discovered in the dry state with a range of 0.282 to 0.237, whereas a friction coefficient of 0.229 to 0.189 is observed in the water-lubricated state. Additionally, it is observed that the friction coefficient increases with an increase in sliding speed under both experimental environments. The examination of specimen surfaces reveals that the abrasion is minor in the water-lubricated setting compared with that in the dry state.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1266-1269
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• 2004

The introduction of invasive marine species into new environments by ship's ballast water, attached to ships' hulls and via other vectors has been identified as one of the four greatest threats to the world's oceans by Global Environment Facility (GEF). EMO (International Maritime Organization) is carrying out the international restriction of the effluence suppression and treatment of Ship's ballast water by Ballast Water Management Convention. In this paper, to deal with this international restriction convention and to consider economic potential of ship's ballaster treatment market near future, the equipment and technology of ship's ballaster water treatment was studied.