• Composites Research
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• 제31권5호
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• pp.202-208
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• 2018

In this paper, mechanical and hygroscopic properties of teak sawdust and recycled polypropylene (RPP) composites are evaluated and compared with virgin polypropylene (VPP) matrix based composites. Verities of composites are prepared by variation in the plastic types, wood plastic ratio and the addition of coupling agent in the formulations. Mixing of wood sawdust and polypropylene is done by a twin screw extruder, and then sheets of wood plastic composites (WPCs) are produced by using the compression molding method. The results show that recycled matrix composites exhibit better tensile, flexural strength with low impact strength than virgin matrix based composites. Recycled composites show low water absorption and thickness of swelling than virgin matrix based composites. The results confirm that wood content in the polymer matrix affects the performance of composites while presence maleated polypropylene (MAPP) improves the properties of the composites significantly. Developed RPP matrix composites are as useful as VPP matrix composites and have the potential to replace the wood and plastics products without any adverse effect of the plastics on the environment.

• 천문학회지
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• 제40권4호
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• pp.127-129
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• 2007

It is well known that water vapor maser emission at 22.2 GHz is associated with the earliest stages of both low- and high-mass star formation and it can be considered a reliable diagnostic of their evolutionary state. Bright Rimmed Clouds (BRCs) are clouds that have been compressed by an external ionization-shock front which focuses the neutral gas into compact globules. The boundary layer between the neutral gas and the gas ionized by the incident photons is often called "bright rim" but the clumps are sometimes classified also as speck globules or cometary globules depending on their appearance. Small globules with bright rims have been considered to be potential sites of star formation and have been studied in several individual regions. We present results from high resolution VLA observations searching for new candidates of recent star formation in bright-rimmed clouds/globules associated with IRAS point sources.

• 한국지열·수열에너지학회논문집
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• 제9권2호
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• pp.1-7
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• 2013

Most researches done on heat pumps have been on heat pumps for refrigeration, cooling and heating. There is therefore the need for more research on hot water heat pumps, especially for high temperature. Even though the cascade heat pump cycle has a great potential more efficient hot water generation even at low evaporating temperatures, it has been researched least for this purpose. In this study, the heating performance of a variable speed cascade heat pump was investigated by varying operating conditions. For the same heating capacity values, it was found that increasing the low stage compressor speed was more suitable for enhancing the performance of the system to get a higher temperature.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2002년도 추계 수산관련학회 공동학술대회발표요지집
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• pp.108-109
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• 2002

Electrolyzed chlorous solutions, or electrolyzed oxidizing water [EW(+)] has attracted much recent attention as a low cost, but high-performance, new technology of potential use by food industry. the term EW(+) is used to describe an aqueous disinfectant produced by the electrolysis of a chlorine containing solution under a low-voltage direct current (Suzuki et al., 2002). (omitted)

• 한국환경과학회지
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• 제8권1호
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• pp.61-67
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• 1999

Silicone oil has organic and inorganic properties, and its skeleton is polysiloxane bonding that silicon is bonded hydrogen or organic group. Silicone compounds are very smooth and lubricant properties by low surface tension, low temperature dependence, and nonadhesive properties. Because of these properties, silicone compounds are used as many parts of chemicals, softener, smooth and libricant agents, water-repellent agent, and defoaming agent, etc. Emulsion was prepared with the inversion emulsification method which adopted the agent-in-oil method dissolving the polyoxyethylene(7) tridecyl ether(HLB 12.2) into methoxy terminated poly(dimethyl-co-methyl amino) siloxane and hydroxy terminated poly(dimethyl-co-methyl amino) siloxane in water. At this time, processed emulsion was almost microemulsion. When ratio of emulsifier increases, emulsion is stable bacuause microemulsion is solubilized by emulsion drop size and zeta-potential are decreased. But, when amount of electrolyte is increase, emulsion became unstable because emulsion drop size is increased.

• 상하수도학회지
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• 제20권5호
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• pp.737-745
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• 2006

The goal of this study is to present an external pit corrosion rate($p_{ecr}$) model with considering both the age of pipe and the soil characteristics. The correlation of nonlinear exponential model among conventional empirical models was a little higher than other empirical models in the prediction of $p_{ecr}$ according to the age of pipe. However, there has been a limit to predict Peer with the model by using only a pipe age since installation as a variable. The soil analysis results from sixty nine samples showed that all of the samples were non corrosive in the assessment of ANSI/AWWA scoring system. The correlation of soil corrosion factors and $p_{ecr}$ was also low. The application result of linear and nonlinear regression models that soil characteristics only showed a low correlation with $p_{ecr}$ Proposed nonlinear regression model in this study, with considering both the age of pipe and the soil characteristics, showed a little higher correlation ($R^2=0.46$) than conventional model.

• 상하수도학회지
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• 제18권2호
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• pp.208-214
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• 2004

Dissolved air flotation (DAF) is an effective solid/liquid separation process for low density floc particles such as algal, color-alum and clay-alum flocs produced from low turbidity water. The removal of taste and odor-causing organics (2-mthylisoboneol and geosmin) originating from algae in drinking water is a local and worldwide concern. Although DAF has been effectively applied for the removal of suspended solid, its application for the treatment of dissolved organic carbon is very limited. In this study, a new hybrid system consisting of adsorption and DAF processes was introduced for the simultaneous removal of algae and taste and odor-causing organics. Powdered activated carbon (PAC) was used as an adsorbent. In this proposed system, the major concern of eliminating the spent PAC from the system was also addressed. It was found that zeta potential of algae and PAC was increased with coagulant dosage, and the removal efficiency in DAF was also enhanced up to 90~95% under the given experimental conditions. Based on this study, the hybrid process was found to be a promising technology for the simultaneous removal of algae and dissolved organic pollutants.

• Ocean and Polar Research
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• 제29권4호
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• pp.349-366
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• 2007

Seasonal variations of various physicochemical components (temperature, salinity, pH, DO, COD, DOC, nutrients-silicate, DIN, DIP) and potential limiting factor for phytoplankton primary production were studied in the surface water of semi-enclosed Masan Bay. Seasonal variations of nutrient concentrations, with lower values in summer and winter, and higher in fall, are probably controlled by freshwater loadings to the bay, benthic flux and magnitude of occurrence of phytoplankton communities. Their spatial distributional patterns are primarily dependent on physical mixing process between freshwater and coastal seawater, which result in a decreasing spatial gradient from inner to outer part of the bay. In the fall season of strong wave action, the major part of nutrient inputs (silicate, ammonium, dissolved inorganic phosphorus) comes from regeneration (benthic flux) at sediment-water interface. During the summer period, high Si:DIN and Si:DIP and low DIN:DIP relative to Redfield ratios suggest a N- and secondarily P-deficiency. During other seasons, however, silicate is the potential limiting factor for primary production, although the Si-deficiency is less pronounced in the outer region of the bay. Indeed, phytoplankton communities in Masan Bay are largely affected by the seasonal variability of limiting nutrients. On the other hand, the severe depletion of DIN (relatively higher silicate level) during summer with high freshwater discharge probably can be explained by N-uptake of temporary nanoflagellate blooms, which responds rapidly to pulsed nutrient loading events. In Masan Bay, this rapid nutrient consumption is considerably important as it can modify the phytoplankton community structures.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1404-1410
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• 2009

Chestnut flours (CFs) were produced from 3 chestnut samples (Aydin, Kutahya, and Bursa) by 2 different methods (boiled and oven-dried: BOD-CF and freeze-dried: FD-CF). Functional properties and effects of CF addition (10, 20, and 30%) on the qualities of regular and low-fat cookie were investigated. The freeze drying significantly increased water solubility of CFs but decreased their water binding capacity. The emulsion capacity and stability of FD-CFs were higher than those of BOD-CFs. At pH 4, 6, 8, and 10 FD-CFs had better gelation properties. Spread ratio (SR) values of BOD-CF supplemented regular or low-fat cookies decreased with increasing CF levels. Hardness values of CF supplemented regular cookies were generally lower compared to control. SR and hardness values of FD-CF supplemented cookies were higher than those of BOD-CF supplemented ones. Surface colors of the cookies were darker with FD-CF addition as compared to BODCF addition. In low-fat cookies, the sample supplemented with 10% Kutahya FD-CF had the highest taste-flavor value. FDCF supplementation generally resulted in higher appearance and taste-flavor scores than BOD-CF supplementation in cookies.

• 한국가스학회지
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• 제9권4호
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• pp.6-10
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• 2005

이 논문은 비저항에 따른 가스보일러용 오스테나이트계 스테인리스강(STS304)재의 손상거동에 관해 연구하기 위하여, 비저항에 따른 전기화학적 분극시험을 수행하였다. 그리고 비저항에 따른 가스보일러용 STS304강의 양극분극특성 및 손상거동인 공식양상을 고찰하였다. 비저항이 감소할수록 STS304강의 부동태유지전류밀도는 증가하고 부동태영역은 작아지고 있으며, 관통전위는 낮아지고 있다 또한 비저항이 가장 높은 $74{\Omega}{\cdot}m$중에서 손상거동인 공식양상은 거의 나타나지 않고, 비저항이 낮아질수록 손상거동인 공식양상은 더욱 성장되고, 공식수가 점점 증가하는 경향을 보이고 있다.