• Title/Summary/Keyword: conditions of evaporation

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Study of Mössbauer Spectroscopy for Iron Oxides Synthesized by Pulsed Wire Evaporation (PEW) (전기선폭발법으로 제조된 철산화물의 뫼스바우어분광연구)

  • Uhm, Young Rang
    • Journal of the Korean Magnetics Society
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    • v.24 no.5
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    • pp.135-139
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    • 2014
  • Iron-oxide nanopowders were synthesized by a pulsed wire evaporation (PWE) in various ambient gas conditions. SEM measurement indicates that the spherical iron nanoparticles are about 50 nm in diameter. The phase analysis for the produced iron-oxide powders was systematically investigated by using $M\ddot{o}ssbauer$ spectra and the results show that classified phases of $Fe_2O_3$ and $Fe_3O_4$ can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process. A quadrupole line on the center of $M\ddot{o}ssbauer$ spectrum represents the superparamagnetic phase of 12 % from ${\gamma}-Fe_2O_3$ phase.

Study on Change of Thermal Conductivity According to Environmental Conditions (환경 조건에 따른 열전도율 변화에 관한 연구)

  • Seo, Eun-Seok;Kim, Bong-Joo;You, Nam-Gyu;Hong, Sang-Hun;Kim, Han-Nah;Jung, Ui-In
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.66-67
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    • 2019
  • Insulated buildings are exposed to the external environment due to aging and construction problems, resulting in a decrease in building energy efficiency. Therefore, the purpose of this paper is to provide a material for the change in thermal conductivity of the insulation when it is exposed to various external environments. In the experiment, five types of heat insulating materials were selected, stored under different environmental conditions, and the thermal conductivity was measured periodically to confirm the change in thermal conductivity. As a result, the thermal conductivity of all the insulating materials except the PF board increased with the passage of time. This is because thermal insulation absorbs atmospheric moisture under all environmental conditions and the thermal conductivity increases, and in the case of thermal insulation stored indoors in environmental conditions, the temperature differs from the thermal insulation stored outside. It is considered that there is little evaporation of moisture absorbed constantly, and the change in thermal conductivity is large.

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Performance Characteristics of Two-stage Compression Seawater Ice Machine Applied Drum type Evaporator (드럼형 증발기를 적용한 2단 압축 해수 제빙시스템의 성능 특성)

  • Son, Chang-Hyo;Yoon, Jeong-In;Jeon, Min-Ju;Lee, Hyun-Kyung;Heo, Seong-Kwan
    • Journal of Power System Engineering
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    • v.21 no.2
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    • pp.77-82
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    • 2017
  • In the fishing boat, freshwater ice is loaded on the fishroom in advance and it is used for storage of fishes. However, it causes degradation of catches' freshness. Therefore, seawater ice machine on board is necessary for the fishing industry. In this study, seawater ice machine with drum type evaporator was manufactured, and the system was tested under various operating conditions having an influence on the COP and amount of ice produced. The main results are as follow : The COP of the system gets larger when the evaporation temperature and rotation speed of the drum in the evaporator increases. The most effective refrigerant is R22 and the value of the COP was 1.43 times higher than that of R404A. The amount of produced ice increases with respect to increment of the evaporation temperature, while that decreases with respect to increment of the evaporator drum rotation speed.

A Study on the preparation of optimum piezoelectric organic thin films of PVD method and switch characteristic (진공증착법을 이용한 최적의 압전성 유기박막의 제조와 스위치 특성에 관한 연구)

  • 박수홍;이선우;이희규
    • Journal of the Korean Vacuum Society
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    • v.8 no.3A
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    • pp.194-200
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    • 1999
  • In this paper studied was the piezoelectric properties of the $\beta$-PVDF organic thin films prepared by physical vapour deposition method. The molecular orientation of organic thin films was controlled by the application of an electric field and variation of substrate temperature during the evaporation process. Optimum conditions of manufacturing $\beta$-PVDF organic thin film by physical vapor deposition method is to keep at the substrate temperature of $80^{\circ}C$, at the applied electric field of 142.8 kV/cm. The voltage output coefficient increased from 1.39 to 7.04V increasing the force moment.

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Atomization and Evaporation Characteristics of DME Fuel for the Application of HCCI Diesel Engine (HCCI 디젤엔진 연료적용을 위한 DME 연료 미립화 및 증발특성)

  • Chon, Mun-Soo;Hwang, Yong-Ha;Suh, Hyun-Kyu;Lee, Chang-Sik
    • Journal of ILASS-Korea
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    • v.11 no.3
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    • pp.140-146
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    • 2006
  • The objective of this work is to analyze the atomization and evaporation characteristics of dimethyl ether(DME) fuel for the application of HCCI diesel engine. In order to investigate the spray behavior of DME fuel, the macroscopic and microscopic characteristics were investigated in terms of spray development, spray tip penetration, impingement time, SMD, and axial mean velocity under the various injection timing and ambient conditions. For the illumination of spray, the spray visualization system was composed of a Nd:YAG laser and an ICCD camera and laser-sheet method was used. The atomization characteristics of DME fuel are analyzed by using phase Doppler particle analyzer (PDPA) system It was reveal that the spray development of DME is slower and rapidly disappeared as elapsed time after start of injection at the same injection duration. The impingement timing of diesel fuel was fester than that of DME fuel. The comparison of spray atomization characteristics in both fuels shows that diesel fuel has a large SMD value that DME.

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Effect of Refrigerated and Thermal Storage on the Volatile Profile of Commercial Aseptic Korean Soymilk

  • Kim, Hun;Cadwallader, Keith R.;Jeong, Eun-Jeong;Cha, Yong-Jun
    • Preventive Nutrition and Food Science
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    • v.14 no.1
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    • pp.76-85
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    • 2009
  • This study determined the effect of refrigerated and thermal storage on the volatile profile of commercial aseptic soymilk. Volatile components in commercial aseptic soymilk stored either under refrigerated ($4^{\circ}C$) or thermal ($55^{\circ}C$) conditions for 30 days were periodically analyzed by combined solvent-assisted flavor evaporation-gas chromatography-mass spectrometry (SAFE-GC-MS). The concentrations of most of the volatile components, including aldehydes, ketones, alcohols, acids, nitrogen- and sulfur-containing compounds, alkylfurans, furan derivatives and phenolic compounds, were affected to a greater extent by thermal storage compared with refrigerated storage. Profound increases in some volatile compounds with low odor detection thresholds, such as hexanal, octanal, (E)-2-octenal, (E,E)-2,4-decadienal, 1-octen-3-ol, 3-ethyl-2,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 2-pentylfuran, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, dimethyl trisulfide, guaiacol, 4-vinylguaiacol and 4-vinylphenol, were observed in thermal stored soymilk. The volatile profile changes caused by thermal storage may influence the aroma quality of thermal-stored aseptic soymilk.

A Study on an Integrated Drying Machine with Microwave at Vacuum Conditions (진공고주파를 이용한 일체형 건조기개발에 관한 연구)

  • Kim, Taehyung;Ko, Gwang-Soo;Park, Youn Cheol
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.9
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    • pp.441-446
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    • 2014
  • In Jeju province, the Citrus is widely spread crop which is the most popular fruit on the island. When the quality of a Citrus is not in a good condition or when its size exceeds or is lower than the set criteria, it is discarded as a waste. In this study, a drying machine for waste Citrus has been developed with 2.6 GHz microwave energy supply to the Citrus at vacuum environment. The vacuum environment of the drying chamber was maintained to reduce the energy supply to the Citrus by lowering the evaporating temperature of the water. The experiment was conducted with variation of the vacuum pressure, interior temperature of the drying chamber, and operating time of the microwave. As a result, the effect of the temperature was shown to be higher than the other two control methods, and it showed with 0.305 g/W evaporation efficiency.

Combustion and Exhaust Emission Characteristics by the Change of Intake Air Temperature in a Single Cylinder Diesel Engine (단기통 디젤엔진에서 흡기온도변화에 따른 연소 및 배기특성)

  • Shin, Dalho;Park, Suhan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.25 no.3
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    • pp.336-343
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    • 2017
  • Intake air conditions, such as air temperature, pressure, and humidity, are very important parameters that influence engine performance including combustion and emissions characteristics. The purpose of this study is to investigate the effects of intake air temperature on combustion and exhaust emissions characteristics in a single cylinder diesel engine. In this experiment, an air cooler and a heater were installed on the intake air line and a gas flow controller was installed to maintain the flow rate. It was found that intake air temperature induced the evaporation characteristics of the fuel, and it affects the maximum in-cylinder pressure, IMEP(indicated mean effective pressure), and fuel consumption. As the temperature of intake air decreases, the fuel evaporation characteristics deteriorate even as the fuel temperature has reached the auto-ignition temperature, so that ignition delay is prolonged and the maximum pressure of cylinder is also reduced. Based on the increase in intake air temperature, nitrogen oxides(NOx) increased. In addition, the carbon monoxide(CO) and unburned hydrocarbons(UHC) increased due to incomplete fuel combustion at low intake air temperatures.

Study of space charge of metal/copper(II)-phthalocyanine interface (금속/copper(II)-phthalocyanine interface에서의 space charge 연구)

  • Park, Mie-Hwa;Lim, Eun-Ju;Yoo, Hyun-Jun;Lee, Kie-Jin;Cha, Deok-Joon;Lee, Young-San
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.526-530
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    • 2004
  • We report the space charge and the surface potential of the interface between metal and CuPc according to isotropic property and different metal by measuring the microwave reflection coefficients $S_{11}$ of copper(II)-phthalocyanine(CuPc) thin films by using a near-field microwave microscope(NSMM) in order to understand. CuPc thin films were prepared on gold and aluminium substrates using a thermal evaporation method. Two kinds of CuPc thin films were prepared. One was deposited on preheated substrate at $150^{\circ}C$ and the other was annealed after deposition by using thermal evaporation methods. The microwave reflection coefficients $S_{11}$ of CuPc thin films were changed by the dependence on the heat treatment conditions. By comparing reflection coefficient $S_{11}$ we measured electrical conductivity of CuPc thin films and studied this results with respect to the surface potential and space charge of the interface between metal and CuPc thin films.

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Surface Chemical Reactions for Metal Organic Semiconductor Films by Alternative Atomic Layer Deposition and Thermal Evaporation

  • Kim, Seong Jun;Min, Pok Ki;Lim, Jong Sun;Kong, Ki-Jeong;An, Ki-Seok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.166.2-166.2
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    • 2014
  • In this work, we demonstrated a facile and effective method for deposition of metal tetraphenylporphyrin (MTPP) thin film by a combined a thermal evaporation (TE) and atomic layer deposition (ALD). For the deposition of Zn-TPP thin film, Tetraphenylporphyrin (TPP) and diethyl zinc (DEZ) were used as organic and inorganic materials, respectively. Optimum conditions for the deposition of Zn-TPP thin film were established systematically: (1) the exposure time of DEZ as inorganic precursor and (2) the substrate temperature were adjusted, respectively. As a result, we verified that the surface reaction between organic semiconductor (TPP) and metal atom (Zn) was ALD process. In addition, we calculated activation energy by using Arrhenius equation for the substrate temperature versus area change rate of pyrrolic nitrogen. The surface and interface reactions between TPP with Zn were investigated by X-ray photoelectron spectroscopy, Raman spectroscopy, UV-vis spectroscopy, and scanning electron microscopy. These results show a facile and well-controllable fabrication technique for the metal-organic thin film for future electronic applications.

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