• 제목/요약/키워드: Surface concentration

검색결과 6,117건 처리시간 0.035초

Properties of Ni-SiC Composite Coating Layers Prepared by Electroplating Method (전해도금법으로 형성한 Ni-SiC 복합피막층의 특성)

  • Lee, Hong-Kee;Son, Seong-Ho;Lee, Ho-Young;Koo, Seok-Bon;Jeon, Jun-Mi
    • Journal of the Korean institute of surface engineering
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    • 제39권4호
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    • pp.160-165
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    • 2006
  • Ni-SiC composite coating layers were prepared by electroplating method and their deposition rate, codeposition of SiC, morphology, surface roughness, hardness, wear and friction properties were investigated. It was found that the deposition rate and the codeposition of SiC in the composite coating layer increased with increasing concentration of SiC in the solution only at the early stage. Both of them reached certain maxima and then decreased with increasing concentration of SiC. Rough surface was obtained with increasing codeposition of SiC, which is probably due to the agglomeration of the SiC particle in the vicinity of surface. Vickers hardness increased with increasing codeposition of SiC and heat treatment at $300^{\circ}C$ in air for 1 hour. Wear volume decreased with increasing codeposition of SiC and friction coefficient increased with increasing codeposition of SiC at the early stage, and it became almost constant. Such wear and friction behaviors are desirable for the practical application.

Variation Analysis of CO2 Concentrations at Sunset before and after of Summer Season at the Foreshore (갯벌에서 여름철 일몰 전후 이산화탄소 농도 변동 분석)

  • Kang, Dong Hwan;Kwon, Byung Hyuk;Kim, Park Sa
    • Journal of Environmental Science International
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    • 제23권3호
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    • pp.399-407
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    • 2014
  • In this study, before and after sunset carbon dioxide concentration and air temperature were observed in two points of atmosphere (lower observation point of the GL + 0.1 m, the upper observation point of GL + 1.0 m) on the foreshore at located in Suncheon Bay and their variations were analyzed. Observation was performed on the foreshore on 2~4 August 2010. Instrument (VAISALA, GMP343) was set two hours before sunset and then observation was made continuously for six hours. In three days, observed carbon dioxide concentration was 375~419 ppm, and the air temperature was in the range of $28.7{\sim}32.5^{\circ}C$. The average concentration of carbon dioxide was 388~399 ppm in the upper observation point and 386~396 ppm in the lower observation point. It was higher in the upper observation point and its fluctuations were similar in two observation points. Correlation coefficients between carbon dioxide concentration and air temperature in the upper observation point were in the range of -0.64~-0.88, and were calculated -0.65 to -0.90 in the lower observation point. For the carbon dioxide concentration, correlation coefficients between the upper part and the lower part were very high as 0.98 in three times. For the air temperature, correlation coefficients between the upper part and the lower part were very high as 0.97 and 0.99. In the same observation time, the slope of the linear regression function as carbon dioxide concentration in the lower observation point for the upper observation point was in the range of 0.97~1.01. Carbon dioxide concentration was slightly higher in the upper observation point. Because carbon dioxide in the lower observation point was closer on the surface of the foreshore and absorbed from atmosphere to the foreshore. In this study, it was showed that the vertical variation of carbon dioxide concentration was insignificant in the several meter scale of atmosphere on the surface of the foreshore.

A Study on Test Variables Effected on Grain Boundary Etching Test (입계부식시험에 영향을 주는 시험변수에 관한 연구)

  • Baek, Seung-Se;Na, Seong-Hun;Lee, Hae-Mu;Yu, Hyo-Seon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • 제25권12호
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    • pp.1911-1918
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    • 2001
  • Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However, during in-serviced GEM test there are a lot of variables such as the changes of temperature and concentration of etching solution, the roughness condition of surface polished etc.. The purpose of this paper is to investigate the influences of these test variables on GEM test results in order to establish a reliable and sensitive of GEM evaluation technique. The experiments are conducted in various solution temperatures, 10$\^{C}$, 15$\^{C}$, 20$\^{C}$, and 25$\^{C}$ and in 70% and 100% concentrations of that, and in various surface roughnesses polished by #800, #2000, and 0.3㎛ alumina powder. Through the test with variables, it is verified that the decrease of temperature and concentration of etching solution and the coarsened surface roughness by not using polishing cloth and powder induce some badly and/or greatly influences on GEM test results like grain boundary etching width(W$\_$GB) and intersecting point ratio(N$\_$i/N$\_$0/). Therefore, to get reliable and good GEM test results, it must be prepared the surface of specimen polished by polishing cloth and 0.3㎛ alumina powder and the saturated picric acid solution having 25$\^{C}$ and be maintained the constant temperature(25$\^{C}$) during GEM test.

Evaluating Ecotoxicity of Surface Water and Soil Adjacent to Abandoned Metal Mines with Daphnia magna and Eisenia fetida

  • Kim, Dae-Bok;Choi, Won-Suk;Hong, Young-Kyu;Kim, Soon-Oh;Lee, Sang-Woo;Lee, Byung-Tae;Lee, Sang-Hwan;Park, Mi-Jung;Kim, Sung-Chul
    • Korean Journal of Soil Science and Fertilizer
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    • 제49권1호
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    • pp.81-86
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    • 2016
  • Heavy metal pollution in agricultural fields at the abandoned metal mines has been serious problems in Korea. In order to manage heavy metal pollution in surface water and soil, numerous remediation strategies have been established. Therefore, main purpose of this research was to examine feasibility of ecological toxicity assessment for establishing management strategy in heavy metal polluted agricultural fields. Heavy metal concentration in surface water and soil was monitored along with ecotoxicity experiment with Daphnia magna and Eisenia fetida. Result showed that high toxicity was observed in heavily polluted agricultural field with heavy metals. In case of mortality of Daphnia magna (85%) and Eisenia fetida (6.7%), the highest ratio was observed when heavy metal concentration in surface and soil was high. Calculated ecotoxicity index (EI) ranged 0.06-0.30 and the highest EI was observed in heavily polluted sites among 5 abandoned metal mines. Overall, ecological toxicity assessment is necessary to evaluate heavy metal pollution in agricultural fields near at the abandoned metal mines along with chemical concentration analysis.

Gel Type Formulation Utilizing Polymer-Surfactant Interaction (폴리머와 계면활성제의 상호작용을 이용한 젤타입 제형의 제조)

  • Kim, Dong-Joo;Kang, Tae-Jun;Lee, Cheon-Koo;Lee, Jung-No
    • Journal of the Society of Cosmetic Scientists of Korea
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    • 제33권1호
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    • pp.7-10
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    • 2007
  • The interaction between polymers and surfactants was investigated by means of rheological and surface tension measurements. The polymers used in this study were acrylates/$C_{10-30}$ alkyl acrylate crosspolymer (AC) and ammonium acryloyldimethyltaurate/VP copolymer (AV). And the surfactants were PEG-40 hydrogenated castor oil (HC) and polysorbate 60 (P60). HC and P60 made the micelles intervening between AC polymers, resulting in the increase of viscosity. However, HC showed a similar behavior over the wider range of surfactant concentration than P60. Regarding of surface tensions in the same range of surfactant concentration, AC/HC solution showed the area of increasing surface tension with surfactant concentration in contrast to the AC/P60 solution showing no increasing area. It is assumed that the micelles between AC/HC were formed so cooperatively and strongly that the surfactants located at the surface originally moved to the micelles.

Desorption characteristics of Activated Carbon and Activated Carbon Fiber by Development of Sorbent Tube for Measurement of Organic Solvent (유기용제 측정용 흡착관 개발을 위한 AC 및 ACF의 흡착특성)

  • 원정일;김기환;신창섭
    • Journal of environmental and Sanitary engineering
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    • 제17권3호
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    • pp.99-109
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    • 2002
  • Charcoal $tube/CS_2$ method are more popularly used than any other in the measurement of the working environment for the exposure evaluation of organic solvent, but it is some weak points that the lower accuracy can be obtained on the polar materials and within the range of the low concentration. Thus solvent desorption method has been developed to make accuracy higher and to overcome some weak points. However, because of high price of adsorption tube for thermal desorption and the short of study on its application to the working environment, it is not popularly used in the domestic industrial hygiene fields. This dissertation aims to develop thermal desorption and adsorption tubes for measuring organic solvents in the working environment, by comparing and analyzing breakthrough condition and adsorption capacity with ACF. Specific surface area of ACF used in this study is wider than the one of AC and micropore of ACF related with adsorption has been developed, and adsorption velocity and adsorption amount are very excellent by linking a pore of surface and an inside well into micropore. 1. Result of analysis on physical characteristics of adsorbent, the specific surface area of ACF was 1.3 times higher than that of AC. Distribution ratio of micropore related to adsorption was 94% on ACF and AC. Result of SEM, micropore of the AC is opened to the surface. In contrast, ACF shows that extremely fast adsorption speed. Because of micropore are exposed on the surface and penetrate through each other. 2. Breakthrough characteristics of adsorbents was not different from slop of breakthrough curve. The effluent concentration reaches 10% of initial concentration($C_{out}/C_{in}=0.1$, break point) of ACF was 30~316min longer than that of AC. Therefore, the adsorption capacities of ACF was 1.1~4.6 times higher than that of AC. ACF can be used as a proper adsorbent for measurement of organic solvent.

Decomposition of Gas-Phase Benzene on TiO2 Coated Alumina Balls by Photocatalytic Reaction (이산화티탄이 코팅된 알루미나 볼에서 광촉매 반응에 의한 기상벤젠의 분해)

  • Lee Nam-Hee;Jung Sang-Chul;Sun Il-Sik;Cho Duk-Ho;Shin Seung-han;Kim Sun-Jae
    • Korean Journal of Materials Research
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    • 제14권6호
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    • pp.407-412
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    • 2004
  • Photo decomposition of gas phase benzene by $TiO_2$ thin films chemically deposited on alumina balls were investigated under UV irradiation. Photo decomposition rates were measured in real time during the reaction using a photo ionization detector, which ionizes C-H bonding of benzene molecules and then converts into volatile organic compounds (VOCs) concentrations. From the measuring results, the VOCs concentration increased instantly when IN irradiated because C-H bonds of benzene molecules strongly absorbed on the surface of $TiO_2$ films before the IN irradiation was destroyed by photo decomposition. After that, the VOCs concentration decreased with increasing surface area of $TiO_2$ and reaction time under the IN irradiation. At the optimal conditions for the photo decomposition of gas phase benzene, the reaction rate of the photo decomposition for high concentrations (over 60 ppm) was slow but that of relatively low concentration (under 60 ppm) was fast, due to limited surface area of $TiO_2$ thin films for the reaction. Thus, it is concluded that the photo decomposition rate was mainly affected by the surface area of $TiO_2$ or absorption reaction.

A Study of the Salt Rejection from the Surface of Marine Waste using Ultra Fine Bubble (초미세기포를 이용한 해양쓰레기 표면 내 염분제거에 관한 연구)

  • Kim, Bo-Min;Kim, Kwang-Koo;Park, Chan-Gyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제22권6호
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    • pp.11-18
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    • 2021
  • Nano bubble water is used in various washing processes, including cleaning of solar panels, salt rejection of roads, and cleaning precision parts of machines. High cleaning efficiency and water conservation are obtained by applying nano bubbles during pretreatment of the marine waste cleaning system. This study compared the salt rejection of nano bubble water, and it was revealed that marine waste was produced by wood immersed in 200,000 mg/L NaCl solution. Using tap water and nano bubble water for washing, comparisons of the surface salt concentrations of wood were determined according to the nozzle, orifice diameter, pump speed and washing time. Decreased surface salt concentration was observed on the wood surface with increasing washing time. Water consumption was optimal between 5- and 10-seconds washing time. Increasing orifice diameter of the nozzle reduced the spraying pressure, with consequent increase in the wood surface salt concentration, thereby establishing the importance of orifice diameter of the nozzle. Compared to levels obtained with tap water, salt concentration of the wood surface after washing with nano bubble water was 2.2% lower with sector nozzle, and 30.9% lower with circular nozzle. In the washing experiment using nano bubble water, the salt concentration on the wood surface was about 9.5 mg/L lower when washed with sector nozzle than the circular nozzle.

Electrochemical Analysis of CdTe Deposition Using Cyclovoltammetric Method for Hybrid Solar Cell Application (나노복합 태양전지를 위한 CdTe 전착 거동의 순환전류법을 이용한 전기화학적 분석)

  • Kim, Seong-Hun;Han, Wone-Keun;Jin, Hong-Sung;Lee, Jae-Ho
    • Journal of the Korean institute of surface engineering
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    • 제42권5호
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    • pp.197-202
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    • 2009
  • The electrodeposition in acidic aqueous electrolyte bath of cadmium telluride on gold electrodes has been studied by electrochemical analysis. Conventional cyclic voltammetry using potentiostat is considered as a reliable method to study electrochemical behavior of electrodeposition of CdTe. In this paper, the mechanism of CdTe deposition and its cyclic voltammetry were studied with the Te ion concentration, temperature, potential, and scan rate. We also investigated surface morphologies using FESEM and atomic composition of Cd and Te using EDS. Atomic composition of Cd and Te were varied with Te ion concentration in the electrolyte.

Separation of Menthol/Water Mixture with Surface-Modified Hydrophobic Membrane (표면개질한 소수성 막을 이용한 menthol/water 혼합물의 분리)

  • Han, Sang-Oh;Song, Kun-Ho;Lee, Kwang-Rae
    • Journal of Industrial Technology
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    • 제22권A호
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    • pp.249-254
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    • 2002
  • The surface of tube-type alumina substrate was modified with a silane coupling agent in order to modify the membrane surface with hydrophobicity. Contact angle of water drops on modified membrane was greater than $90^{\circ}$. The modified membrane was tested in pervaporation and vapor permeation for the recovery of menthol from dilute menthol/water mixture. With increasing menthol concentration in the feed at $45^{\circ}C$, permeation rate of menthol in pervaporation and vapor permeation increased from $0.039(g/m^2hr)$ to $0144(g/m^2hr)$ and from. $0.077(g/m^2hr)$ to $0.297(g/m^2hr)$ respectively. When feed concentration is 0.005(g/L) at $45^{\circ}C$, separation factor for menthol in pervaporation and vapor permeation is 20,7 and 40.5 respectively.

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