• Title/Summary/Keyword: dynamic polarization test

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The Study on the Behavior of Polarization curve of Reinforcement with Oxidation Layer (산화피막이 있는 철근의 분극곡선의 거동에 대한 연구)

  • 한정섭
    • Journal of Ocean Engineering and Technology
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    • v.14 no.1
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    • pp.60-66
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    • 2000
  • In order to study for corrosion behavior of reinforcing steel with oxidation layer. Experiments were done with various NaCl concentrations and with immersion time in simulated concrete pore solution(SPS) the characteristics of corrosion behavior were measured by polarization resistance method and cyclic potentiodynamic method. reinforcements were coated by epoxy except corrosion without oxidation layer and it also showed two anodic-nose. by the result of potention dynamic test the potential curve shift to low with time and anodic-nose was appeared with 3% NaCl solution after 15 days. By result of cyclic Potentiodynamic test the type of corrosion was different accoding to concentration.

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The multipath propagation loss analysis of dynamic telemetry link using the 3D antenna pattern (3차원 안테나 패턴을 사용한 동적 원격측정링크의 다중경로 전파손실 분석)

  • Kim, Kyun-Hoi;Shin, Seok-Hyun;Koh, Kwang-Ryul;Yun, Jung-Kug
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.3
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    • pp.254-260
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    • 2011
  • Telemetry link is dynamic communication link that antenna gain and polarization are varying with the movement of the airplane. In this paper we calculated the antenna gain, polarization mismatch using the flight trajectory, motion of the airplane and 3D antenna pattern. And we modeled the multipath environment to the 2-Ray spherical earth reflection geometry, estimated the received signal strength when the narrow beam antenna received the RF signal transmitted from the airplane. Also we performed the flight test and after comparing measured value with the estimated value, we confirmed to almost coincide with each other.

Effect of Precursor Ratio on the Properties of Inorganic-Organic Hybrid TiO2-SiO2 Coating (유무기 TiO2-SiO2 혼성코팅에 미치는 전구체 배합비율의 영향)

  • Kim, Dong Kyu;Maeng, Wan Young
    • Korean Journal of Materials Research
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    • v.26 no.5
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    • pp.271-280
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    • 2016
  • When a single inorganic precursor is used for the synthesis of a sol-gel coating, there is a problem of cracking on the surface of coating layer. In order to solve this problem of surface cracking, we synthesized inorganic-organic coatings that have hybrid properties of inorganic and organic materials. Sols of various ratios (1:0.07, 0.2, 0.41, 0.82, 1.64, 3.26, 6.54, 13.2) of an inorganic precursor of Tetrabutylorthotitanate ($Ti(OBu)_4$, TBOT) and an organic precursor of ${\gamma}$-Methacryloxy propyltrimethoxysilane (MAPTS) were prepared and coated on stainless steels (SUS316L) by dip coating method. The binding structure and the physical properties of the synthesized coatings were analyzed by FT-IR, FE-SEM, FIB (Focused Ion Beam), and a nano-indenter. Dynamic polarization testing and EIS (electrical impedance spectroscopy) were carried out to evaluate the micro-defects and the corrosion properties of the coatings. The prepared coatings show hybrid properties of inorganic oxides and organic materials. Crack free coatings were prepared when the MAPTS ratio was above a critical value. As the MAPTS ratio increased, the thickness and the corrosion resistance increased, and the hardness decreased.

The Influences of the Globalization Factors on Consumption (소비에 대한 요인별 세계화의 영향 분석)

  • Yoon, Jai-Hyung
    • Asia-Pacific Journal of Business
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    • v.10 no.4
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    • pp.119-135
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    • 2019
  • This study analyzes the effects of trade globalization and financial globalization on consumption classified by type(durable, quasi-durable, non-durable and service). On the other hand, trade globalization and financial globalization were decomposed into OECD common factor, regional factors, and the idiosyncratic country-specific factors by time-varying dynamic factor analysis. The characteristics of OECD common factor, regional factors, and the idiosyncratic country-specific factors of trade and financial globalization were analyzed. Furthermore, the influences of these factors on consumption by type were analyzed. The analysis shows that globalization has negative effects on consumption. In particular, we found out that the idiosyncratic country-specific factor of Korea in trade and financial globalization had a statistically significant negative effect on consumption. We can infer that the globalization affecting consumption can be attributed to the idiosyncratic country-specific factor, which is economic choice rather than uncontrollable global trend. Accordingly, to solve the sluggish consumption problem caused by globalization, it is necessary to require not only domestic consumption expansion policies but also the efforts to resolve economic polarization problems to be able to stimulate consumption.

The Effect of Heat Treatment on the Corrosion-Resistance for Ti-6Al-4V Alloy (Ti-6Al-4V합금의 열처리가 내식성에 미치는 영향)

  • 백신영;나은영
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.3
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    • pp.453-459
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    • 2003
  • In this study, the effect of heat treatment to the electrochemical polarization resistance for the Ti-6Al-4V alloy was measured. The solution heat treatments were carried out at $1066^{circ}E, 966^{\circ}$E$, followed by aging heat treated $550^{circ}E, 600^{circ}E, and 650^{circ}E$. The electrochemical polarization resistance behavior was measured by potentio-dynamic polarization in the 1N $HNO_3$ + 15ppm HF solution. The obtained results were as follows. 1. As solution heat temperature increased. the corrosion potential was increased, whereas passive current density and critical current density were decreased. 2. As aging heat temperature increased, the corrosion potential was almost constant, but passive current density was decreased 3. The results of composition test measured by EDS at grain boundary and near $\gamma'$ precipitates indicated that S, Cl. and Si which originated from base metal were segregated at the grain boundaries Al and Ti which were the main alloying element in $\gamma'$ were depleted at the $\gamma'$ precipitated. The depletion of Al and Ti in $\gamma'$ was caused to early breakdown of passive film.

액정셀의 광학적 동특성 분석을 위한 실시간 측광식 편광계측기 : 제작과 성능시험

  • Yang, Byeong-Kwan;Rho, Bong-Gyu;Park, Chan;Kim, Jin-Seung;Kim, Jae-Ki
    • Korean Journal of Optics and Photonics
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    • v.8 no.6
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    • pp.486-491
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    • 1997
  • A division-of-amplitude type photopolarimeter has been constructed for the analysis of the dynamic optical characteristics of liquid crystal panels, one of the essential components of liquid crystal displays. In this instrument an incoming light ray, whose state of polarization is to be determined, is divided into three rays of nearly same intensities and of identical polarization state by using NPBS'(non-polarizing beam splitters). Each of the three rays is further divided into two components of orthogonal polarization states by using a PBS(polarizing cube beamsplitter) or by using a combination of a quater wave plate followed by a PBS. The intensity of each ray is measured by using a photodiode to produce a set of six photo-signals, which in turn are converted into four Stokes parameters describing the state of polarization of the incoming ray. Performance test of the insrument shows that its time resolution is 80 $mutextrm{s}$, accuracy $\pm$0.3 degrees when the state of polarization of the incoming ray is representated on the Poincare sphere.

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Study of Operation Strategy for Hybrid PEM Fuel Cell and Supercapacitor (고분자 전해질 연료전지와 슈퍼캐패시터 하이브리드 시스템의 운전 전략에 관한 연구)

  • Park Kwang-Jin;Ji Hyun-Jin;Bae Joong-Myeon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8 s.251
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    • pp.756-763
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    • 2006
  • PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.

Development of Corrosion Rust Removing Unit for Small Ship Propeller (소형선박용 프로펠러의 부식 녹 제거장치 개발)

  • Kim, Gui-Shik;Han, Se-Woong;Hyun, Chang-Hae
    • Journal of Ocean Engineering and Technology
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    • v.19 no.6 s.67
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    • pp.72-77
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    • 2005
  • The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.

A Study on the Corrosion Resistance of Free Cutting Steels after Oxy-Nitriding (진공산질화기술에 의한 쾌삭강의 내부식성 향상기술)

  • Moon, Kyoung Il;Kim, Sang Gweon;Kim, Sung Wan
    • Journal of the Korean Society for Heat Treatment
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    • v.19 no.2
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    • pp.90-95
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    • 2006
  • Nitriding or carburizing of carbon steels results in good mechanical properties such as high surface hardness and wear resistance but it has no affection on the corrosion resistance. Corrosion properties of nitriding and carburizing steels could be deteriorated. So, recently, there have been great demand for oxi-nitriding to enhance both mechanical properties and corrosion resistance. In this study, the corrosion resistance of carbon steel, S35C, and free cutting steel, SUM222, are prepared by vacuum nitriding and vacuum post-oxidation were compared with those treated by nitriding. After vacuum post-oxidation, $5{\mu}m$ oxide layer was formed on the nitride layer with $20{\sim}30{\mu}m$ depth. Potentio-dynamic polarization curve in corrosion test showed that the corrosion potential after post oxidation was increased from 200 mV to 800 mV in S35C and from 600 mV to 1200 mV in SUM222. SEM analyses showed that pores was increased and surface roughness became rougher with post oxidation. However, the formation of $Fe_3O_4$ resulted in the enhanced corrosion resistance of steels.

Development and performance test of a complex laser interferometer for simultaneously measuring displacement and 2-D angles (변위 각도 동시 측정용 복합 레이저 간섭계의 제작과 특성 분석)

  • Kim J.W.;Kim J.A.;Kang C.S.;Eom T.B.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.573-576
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    • 2005
  • A compact linear and angular displacement measurement device was developed by combining a Michelson interferometer and an autocollimator to characterize the movement of a precision stage. A Michelson interferometer and an autocollimator are typical devices for measuring linear and angular displacement, respectively. By controlling the polarization of reflected beam from the target mirror of the interferometer, some part of light was retro-reflected to the light source and the reflected beam was used for angle measurement. The interferometer and the autocollimator use the same optic axis and the target mirror can be easily and precisely aligned orthogonal to the optic axis by monitoring the autocollimator s signal. The autocollimator was designed for angular resolution of 0.1 arcsec and dynamic range of 60 arcsec. The nonlinearity error of interferometer was minimized by trimming the gain and offset of the photodiode signals. Through the experiments, we evaluate the performance of measurement device and discuss its applications.

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