• Title/Summary/Keyword: conductivity measurement

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Influence of Neutral Particle Beam Energy on the Structural Properties of Amorphous Carbon Films Prepared by Neutral Particle Beam Assisted Sputtering

  • Lee, Dong-Hyeok;Jang, Jin-Nyeong;Gwon, Gwang-Ho;Yu, Seok-Jae;Lee, Bong-Ju;Hong, Mun-Pyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.194-194
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    • 2011
  • The effects of argon neutral beam (NB) energy on the amorphous carbon (a-C) films were investigated, while the a-C films were deposited by neutral particle beam assisted sputtering (NBAS) system. The energy of neutral particle beam can be controlled by reflector bias voltage directly as a unique operating parameter in this system. The deposition characteristics of the films investigated of Raman spectra, UV-visible spectroscopy, electrical conductivity, stress measurement system, and ellipsometer indicate the properties of amorphous carbon films can be manipulated by only NB energy (or reflector bias voltage) without changing any other process parameters. We report the effect of reflector bias voltage in the range from 0 to -1KV. By the increase of the reflector bias voltage, the amount of cross-linked sp2 clusters as well as the sp3 bonding in the a-C film coated by the NBAS system can be increased effectively and the composition of carbon thin films can be changed from nano-crystalline graphite phase to amorphous carbon phase.

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Condensable InP Quantum Dot Solids

  • Tung, Dao Duy;Dung, Mai Xuan;Jeong, Hyun-Dam
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.541-541
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    • 2012
  • InP quantum dots capped by myristic acid (InP-MA QDs) were synthesized by a typical hot injection method using MA as stablizing agent. The current density across the InP-MA QDs thin film which was fabricated by spin-coating method is about $10^{-4}A/cm^2$ at the electric field of 0.1 MV/cm from I-V measurement on a metal-insulator-metal (MIM) device. The low conductivity of the InP-MA QDs thin film is interpreted as due to the long interdistances among the dots governed by the MA molecules. Therefore, replacing the MA with thioacetic acid (TAA) by biphasic ligand exchange was conducted in order to obtain TAA capped InP QDs (InP-TAA). InP-TAA QDs were designed due to: 1) the TAA is very short molecule; 2) the thiolate groups on the surface of the InP-TAA QDs are expected to undergo condensation reaction upon thermal annealing which connects the QDs within the QD thin film through a very short linker -S-; and 3) TAA provides better passivation to the QDs both in the solution and thin film states which minimizing the effect of surface trapping states.

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Measurement of Liquid Entry Pressure of PE and PVDF Hollow Fiber Membranes in Membrane Distillation Process (막증류 공정에서 PE 및 PVDF 중공사막의 액체투과압력 측정에 관한 연구)

  • Min, Ji Hee;Park, Min Soo;Kim, Jinho
    • Membrane Journal
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    • v.25 no.3
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    • pp.216-222
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    • 2015
  • The method measuring LEP (liquid entry pressure) was optimized to evaluate the wettabilities of hydrophobic membranes which might affect long-term durability of membrane in MD (membrane distillation) process. Conductivity of the permeate was monitored to measure the LEPs of PE (polyethylene) and PVDF (polyvinylidene di-fluoride) hollow fiber membranes from highly concentrated synthetic feed water of 20 wt% NaCl. Holding time over 5 min and the ratio of membrane area to the tank volume more than $10m^2/m^3$ were required to ensure LEP value.

A Study on the Improvement in Performances and Wearing Sensation of Textiles for Taekwondo Wears (태권도복 소재의 성능 및 착용감의 개선을 위한 연구)

  • 전영민;박정희;최정화
    • Journal of the Korean Society of Clothing and Textiles
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    • v.27 no.1
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    • pp.134-142
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    • 2003
  • Performances of Taekwondo fabrics were evaluated in respect of fiber component. yarn count, weave structure and wearing comfort. As a beginning step, we investigated the present situation of Taekwondo wears by questionnaire from pro and amateur Taekwondo players. Samples employed in this study were cotton/nylon blend fabric that was newly woven for this study as well as fabrics of current Taekwondo wears for sale in the market. Their fundamental properties measured were such as air permeability, water vapor transport. wickability, absorption rate, Qmax values, thermal conductivity, durability, hand value, and etc. In addition, subjective wearing sensations were evaluated using Taekwondo wears made of those fabrics. From the results of the objective measurement and the subjective wearing test, we estimated the total fitness of fabrics as a Taekwondo wear. From the questionnaire we could see that pro players and amateurs wanted highly absorbing, quick drying, and soft-tough and complained abrasive surfaces and static elasticity of current fabrics. In view of the results so far achieved, nylon blended fabrics newly woven in this study, showed better comfort-related properties from both of the objective and subjective tests. It was also represented that finer yams enhanced water absorption and touch, and fabrics with rough surface such as honeycomb weave was superior in wearing comfort as well as aesthetic appearance.

Variation of Physical Characteristic of Tidal Flat's Environment by Water Level Change (수위변동에 따른 갯벌의 물리적 환경특성의 변화)

  • Park, Jong-Hwa
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.2 no.3
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    • pp.1-9
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    • 1999
  • This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.

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Characteristics of the Functional Panel Made from Foamed Aluminum (발포알루미늄을 이용하여 제조한 기능성 판넬 특성 연구)

  • Kim, Jae-Yong;Um, Myeong-Heon;An, Dae-Hyun;Shim, Myeong-Jin
    • Applied Chemistry for Engineering
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    • v.17 no.1
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    • pp.62-66
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    • 2006
  • In this work, the properties of environmentally friendly functional panel made from waste aluminum were investigated. Product quality enhancement was pursued through an improved viscosity process, a mixing process by agitating, a foaming process, a cooling process, and a color addition process. An acoustic transmission attenuation test, a sound adsorption rate measurement test, and a foaming condition and scrap mixing test were implemented. As a result, the functional panel made from waste aluminum was ultra lightweight and had excellent properties such as soundproof, sound interception, and shielding harmful electromagnetic waves. Also, the functional panel showed low thermal conductivity (about 2.2 kcal/mh) and excellent heat-insulating property.

A Study of Passive Intermodulation Distortion on RF Connectors (RF 커넥터의 Passive IMD에 관한 연구)

  • 조인귀;이재화;안승호;최상국;정명영;최태구
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.2
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    • pp.268-277
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    • 2000
  • Nowadays, the interference between neighbor basestations is getting higher as mobile communication services expand, then the increase of the interference causes IMD(Intermolulation Distortion) problems for not only active devices but also passive devices. In this paper, we have designed and assembled several adapters having variable plating thickness and materials to analyze PIMD(Passive Intermodulation Distortion) mechanisms for coaxial cables which is one of the representative passive RF devices. The measurement results of the assembled adapters show that IM level depends on conductivity of plating materials, plating thickness, device structure, aging effect and so on. Furthermore, we have obtained PIMD mechanisms and some control methods of PIMD from the results.

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Development of machinery parts test device for the rising high temperature and measuring large and tiny scale torque (기계류부품의 고온상승, 고 토크와 미소토크의 시험장치 개발)

  • Lee, Yong Bum;Park, Hong Won;Lee, Geun Ho
    • Journal of Applied Reliability
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    • v.13 no.1
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    • pp.11-18
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    • 2013
  • For a reliability assessment of machinery parts, accurate performance test, environmental test, life test, etc. are required on the sample. In the performance test conditions of various machinery parts, some problems happen such as needs to rise temperature rapidly with large flow of oil having very low thermal conductivity and to measure very high torque or tiny torque, etc. This study brings out the method to apply heat to rise temperature for large flow of oil without chemical change in a performance test of oil cooler. To measure large scale of torque in a performance test of planetary gearbox of excavator, the method of torque measurement is proposed by replacing the large torque meter priced very expensive. To measure very small torque on lubricated friction, a methode of force balance type test mechanism is introduced for tests of piston assembly.

Application of 4-D resistivity imaging technique to visualize the migration of injected materials in subsurface (지하주입 물질 거동 규명을 위한 4차원 전기비저항 영상화)

  • Kim, Jung-Ho;Yi, Myeong-Jong
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.12a
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    • pp.31-42
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    • 2007
  • Dc resistivity monitoring has been increasingly used in order to understand the changes of subsurface conditions in terms of conductivity. The commonly adopted interpretation approach which separately inverts time-lapse data may generate inversion artifacts due to measurement error. Eventually the contaminated error amplifies the artifacts when reconstructing the difference images to quantitatively estimate the change of ground condition. In order to alleviate the problems, we defined the subsurface structure as four dimensional (4-D) space-time model and developed 4-D inversion algorithm which can calculate the reasonable subsurface structure continuously changing in time even when the material properties change during data measurements. In this paper, we discussed two case histories of resistivity monitoring to study the ground condition change when the properties of the subsurface material were artificially altered by injecting conductive materials into the ground: (1) dye tracer experiment to study the applicability of electrical resistivity tomography to monitoring of water movement in soil profile and (2) the evaluation of cement grouting performed to reinforce the ground. Through these two case histories, we demonstrated that the 4-D resistivity imaging technique is very powerful to precisely delineate the change of ground condition. Particularly owing to the 4-D inversion algorithm, we were able to reconstruct the history of the change of subsurface material property.

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Integrity of Optical Fiber Sensor for Measurement of Ground Thermal Conductivity (지중 열전도도 측정을 위한 광섬유 센서의 건전성)

  • Yoon, Seok;Choi, Jung-Chan;Lee, Seung-Rae;Lee, Michael-MyungSub
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2011.04a
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    • pp.157-160
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    • 2011
  • 본 연구에서는 광섬유 센서 기반 스마트 모니터링 시스템이 지중 열전도도 측정에도 효율적으로 적용될 수 있는지를 분석하였다. 이를 위해 광섬유 온도센서를 이용하여 지반의 열전도도를 측정할 수 있는 열응답 시험기가 개발되었다. 개발된 열응답 시험기는 기존의 RTD(Resistance Temperature Detector) 온도 센서 외에 광섬유 센서의 한 종류인 FBG(Fiber Bragg Grating) 센서도 실시간적으로 측정할 수 있는 시스템으로 구성되어 있다. 개발된 장비의 적용성 검증을 위하여 주문진 표준사를 이용하여 모형토조 내에 일정한 간극비에 맞추어 시료가 조성되었으며 지중열교환기는 U자형 파이프가 사용되었다. 20시간동안 열응답 시험을 통하여 광섬유 센서와 RTD 센서를 동시에 이용하여 온도값을 측정하여 표준사의 열전도도 값을 산출하였다. 그 결과 모형실험을 통한 열전도도 값은 탐침법을 통해 얻어진 열전도도 값과 선형 열원 모델(line source model) 해석해와 거의 유사하게 나타났으며 광섬유 센서와 RTD 센서와의 온도차는 0.1~0.3$^{\circ}$로써 유사한 값을 나타내었다. 따라서 본 연구에서 개발된 광섬유 기반 열응답 시험기는 지반의 열전도도를 측정하는데 효과적으로 사용될 수 있음을 알 수 있었으며 향후 지열시스템 가동에 따른 지중열 교환기의 손상도 평가 및 경보시스템 개발을 위해 지중열교환기의 거동을 실시간으로 모니터링 하는데 있어서도 효과적으로 사용될 수 있을 것으로 생각된다.

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