• Title/Summary/Keyword: surface humidity

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Humidity sensing properties of carbon nitride film according to fabrication conditions (제조 조건에 따른 질화탄소막의 습도 감지 특성)

  • Lee, Sung-Pil;Kim, Jung-Hoon;Lee, Hyo-Ung;Lee, Ji-Gong
    • Journal of Sensor Science and Technology
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    • v.14 no.5
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    • pp.343-349
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    • 2005
  • Carbon nitride films were deposited on various substrates for humidity sensors with meshed electrode by reactive RF magnetron sputtering system. As the ratio of injected nitrogen was decreased, the sensitivity of sensor was increased. When the ratio of injected nitrogen was $50{\sim}70%$, the sample showed the best linearity. The sensor impedance changed from $95.4{\;}k{\Omega}$ to $2.1{\;}k{\Omega}$ in a relative humidity range of 5 % to 95 %. The humidity sensors based on silicon wafer revealed higher lineality and faster response than those of alumina or quartz substrates. The adsorption saturation time of the sample was about 80 sec, and its desorption time was about 90 sec.

Moisture Sorption and Desorption Isotherms of Various Leaf Tobaccos (잎담배의 흡습 및 탈습에 관한 연구)

  • 진학용;최승찬;이태호;유광근
    • Journal of the Korean Society of Tobacco Science
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    • v.3 no.1
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    • pp.30-40
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    • 1981
  • The moisture sorption and desorption isotherms of various tobaccos were obtained over a relative humidity range from 0 to 90% at $20^{\circ}C$ and $30^{\circ}C$. The hysteresis effect, constant and rate of moisture sorption and desorption, monomolecular-layer moisture content, and specific surface area were analyzed from the obtained data. The moisture sorption and desorption isotherms showed a different characteristics for different tobacco varieties. At a lower humidity range below 50% RH, Burley tobacco had higher moisture sorption and desorption figures than Hicks and Basma, while, at a higher humidity range above 50% RH, Hicks had higher values than the others. The hysteresis effect of tobacco were greater in an intermediate humidity range (40-70% RN), and Basma showed a greater effect than the others. The sorption and desorption constant (K) increased with temperature, but decreased with RH, and Burley tobacco had larger K values, while Hicks had smaller K values than others. The sorption and desorption rate of Burley tobacco were greater than the other tobaccos. The monomolecular-layer moisture was 27.8 and 51.4mg/g, and the specific surface was 101 and $186m^2/g$, for Basma and Burley, respectively.

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Accelerated Testing of Coated VCR Drum Under Various Environmental Conditions (환경변화에 따른 VCR 코팅드럼의 가속실험)

  • Park, U-Hyeon;Hwang, Dong-Hwan;Kim, Dae-Eun;Lee, Sang-Jo;Yoo, Dae-Eun;Kim, Geum-Mo;Choi, Gye-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.10
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    • pp.3095-3104
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    • 1996
  • The tribological characteristics of TIN and DLC coated VCR drums were compared to conventional aluminum drums using a custom built accelerated testing set-up under varying temperature and humidity. It is found that the coated drums exhibit superior frictional properties at elevated temperature and high humidity compared to bare aluminum drum. Futhermore, the coated drums maintained their initial surface conditions over a wider range of temperature and humidity variation. As for the damage incurred to the tape, DLC coated drum was the most favorable of the three types of drums.

Experimental study on the effects of EVA(Ethylene Vinyl Acetate) for solar cell's long-term life (EVA(Ethylene Vinyl Acetate) 수지가 태양전지의 장기적인 수명에 미치는 영향에 관한 실험적 연구)

  • Kim, Seon Yong
    • Journal of the Korea Safety Management & Science
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    • v.17 no.4
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    • pp.397-401
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    • 2015
  • In this study, analysed the characteristics of power drop and surface damage in solar cell through high temperature and humidity test in the 3 case of EVA(ethylene vinyl acetate) and 2 case ribbon thickness. The solar cells were tested during the 500hr in $85^{\circ}C$ temperature and 85% relative humidity conditions, that excerpted standard of PV Module(KS C IEC-61215). Through the EL(Electroluminescence) shots, specimen's surface have partialy damaged. Before and after high humidity and high temperature test, ribbon thickness $200{\mu}m$ EVA1 case power drop rate was 8.463%, EVA2 case was 6.667%, EVA3 case was 6.373%. In the ribbon thickness $250{\mu}m$ EVA1 case power drop rate was 6.521%, EVA2 case was 8.517%, EVA3 case was 6.019%. EVA3 case was the lowest power and FF(fill factor) drop rate at the 2 case of ribbon thickness, because EVA3 is laerger than EVA1 and EVA2 in thickness, elongation and tensile strength.

Nanomachining on Single Crystal Silicon Wafer by Ultra Short Pulse Electrochemical Oxidation based on Non-contact Scanning Probe Lithography (비접촉 SPL기법을 이용한 단결정 실리콘 웨이퍼 표면의 극초단파 펄스 전기화학 초정밀 나노가공)

  • Lee, Jeong-Min;Kim, Sun-Ho;Kim, Tack-Hyun;Park, Jeong-Woo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.4
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    • pp.395-400
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    • 2011
  • Scanning Probe Lithography is a method to localized oxidation on single crystal silicon wafer surface. This study demonstrates nanometer scale non contact lithography process on (100) silicon (p-type) wafer surface using AFM(Atomic force microscope) apparatuses and pulse controlling methods. AFM-based experimental apparatuses are connected the DC pulse generator that supplies ultra short pulses between conductive tip and single crystal silicon wafer surface maintaining constant humidity during processes. Then ultra short pulse durations are controlled according to various experimental conditions. Non contact lithography of using ultra short pulse induces electrochemical reaction between micro-scale tip and silicon wafer surface. Various growths of oxides can be created by ultra short pulse non contact lithography modification according to various pulse durations and applied constant humidity environment.

A Study on an Ion Wind Created by a Wire Electrode and Parallel Plates Assembly (와이어 전극과 평행판에서 발생되는 이온풍 특성 연구)

  • 안영철;황필재;이재근
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.4
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    • pp.318-323
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    • 2004
  • When a strong electric field is applied between a sharply curved electrode and a blunt surface, the corona may result in a gas movement in the electrode gap which is directed toward the blunt surface. That is called the corona wind. It enhances heat and mass transfer between the surface and the surrounding gas. Moreover such enhancement causes no noise or vibration, which can be applied in complex, isolated geometries, and allows simple control of surface temperatures. This paper examines the relationship between the corona wind and the relative humidity. The facility consists of high voltage power supply thin tungsten wire, plate electrode, multimeter, microammeter and flow meter. Gas velocity is a linear function of voltage, relative humidity and is proportional to the square root of the current. The maximum velocities for the positive and negative corona discharge are 1.9 m/s (2.74 CMM/m), 1.5 m/s(2.15 CMM/m), respectively.

Tribological Behavior of DLC Coatings at Various Humidities (습도에 따른 DLC 코팅의 마찰 거동)

  • Jo, Gyeong-Man;An, Hyo-Seok;Kim, Dae-Eun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.9
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    • pp.1842-1848
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    • 2002
  • Although DLC coatings have good tribological properties, these are dependant on the deposition method, the property of contact surface, and test condition. Humidity, which has little influence on tribological behavior in macro scale, is an important factor of tribological behavior in small devices like MEMS. The objective of this study is to investigate the tribological behavior of DLC coatings with particular attention to their wettability at various humidities. DLC coatings were deposited on Si substrates and tested using a reciprocating friction tester against Si$_3$N$_4$balls at various humidities. The results showed that the tribological behavior of DLC coatings was dependant on relative humidity and wettablility of DLC coatings. Friction coefficient at high relative humidity was higher thar that at low relative humidity. The tungsten-containing DLC coatings had a good wear resistance at low relative humidity whereas DLC coatings derived from argon(Ar)+cesium(Cs) gases showed a good wear resistance at high relative humidity.

Estimation of Surface Forces in Micro Rough Surface Contacts

  • Kim, Doo-In;Ahn, Hyo-Sok;Choi, Dong-Hoon
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.63-64
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    • 2002
  • In a micro-scale contact, surface forces such as capillary force and van der Waals Interaction significantly Influence the contact between asperities of rough surfaces. Little is, however, known about the variation of these surface forces as a function of chemical property of the surface (hydrophilicity), relative humidity and deformation of asperities In the real area of contact. A better understanding of these surface forces is of great necessity in order to find an optimal solution for reducing friction and adhesion of micro surfaces. We proposed an effective method to analyze capillary and van der Waals forces In nano-scale contact. In this method, Winklerian foundation model was employed to analyze the contact of rough surfaces that were obtained from atomic force microscopy (AFM) height Images. Self-mated contact of diamond-like-carbon (DLC) coatings was analyzed, as an example, by the proposed model. It was shown that the capillary force was significantly influenced by relative humidify and wet angle of the DLC surface. The deformation of asperities to a critical magnitude by external loading led to a considerable increase of both capillary and van der Waals forces.

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Analysis of Surface Forces in Micro Contacts between Rough Surfaces (거친 표면간의 미세 접촉에서의 표면력 해석)

  • Kim, Doo-In;Ahn, Hyo-Sok;Choi, Dong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.10
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    • pp.2180-2186
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    • 2002
  • In a micro-scale contact, capillary force and van der Waals interaction significantly influence the contact between asperities of rough surfaces. Little is, however, known about the variation of these surface forces as a function of chemical property of the surface (wet angle), relative humidity and deformation of asperities in the real area of contact. A better understanding of these surface forces is of great necessity in order to find a solution for reducing friction and adhesion of micro surfaces. The objective of this study is to investigate the surface forces in micro-scale rough surface contact. We proposed an effective method to analyze capillary and van der Waals forces in micro-scale contact. In this method, Winkler spring model was employed to analyze the contact of rough surfaces that were obtained from atomic force microscopy (AFM) height images. Self-mated contact of DLC(diamond like carbon) coatings was analyzed, as an example, by the proposed model. It was shown that the capillary force was significantly influenced by relative humidity and wet angle of the DLC surface. The deformation of asperities to a critical magnitude by external loading led to a considerable increase of both capillary and van der Waals forces.

Evaluation of Humidity Control Ceramic Board Using Gypsum Binder (석고계 바인더를 활용한 습도도절 세라믹 보드의 특성 평가)

  • Lee, Jong-Kyu;Kim, Tae-Yeon
    • Korean Journal of Materials Research
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    • v.28 no.1
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    • pp.62-67
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    • 2018
  • Active clay, bentonite and zeolite were used as porous materials for humidity controlling ceramic boards. The specific area and the pore volume of active clay were higher than bentonite and zeolite. The flexible strength of the gypsum board decreased with an increasing amount of porous material, and the flexible strength was lowest when active clay with a higher specific surface area than others porous materials was added. The specific surface area and total pore volume of ceramic boards containing porous material were highest at $102.25m^2/g$, $0.142cm^3/g$, respectively, when the active clay was added. In addition, as the amount of added porous materials increased, the specific surface area and total pore volume of the ceramic board increased, but the average pore diameter decreased. The addition of s porous materials with a high specific area and a large pore volume improved the moisture absorptive and desorptive performance of the ceramic board. Therefore, in this experiment, the moisture absorptive and desorptive properties were the best when active clay was added. Furthermore, as the amount of added porous materials increased, the moisture absorptive and desorptive properties improved. When 70 mass% of active clay was added to ${\alpha}$-type gypsum, the hygroscopicity was the highest, about $300g/m^2$, in this experiment.