• 한국세라믹학회지
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• 제26권1호
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• pp.1-6
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• 1989

The phenomena that the electrical conductivity of rutile single crystal changes with time were investigated along the a and c crystallographic axes, at 85$0^{\circ}C$ and Po2 in the range of 1~10-18.5atm. The D.C. conductivity decreased with and saturated some value after ca. 100 hours. But the A.C. conductivity showed no time dependence in the whole Po2 range. These experimental results suggest that the time dependence of D.C. conductivity of rutile single crystal is due to space charge polarization effect; the electrode was Pt which is complete electronic conductor, while the sample was TiO2 which is mixed conductor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.214-219
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• 1997

We propose a new scheme of high-resolution heterodyne interferometer that employs the two-axial mode He-Ne laser with an inter-mode beat frequency of 600-1000 MHz. An electronic RF-heterodyne circuit lowers the beat frequency down to 5 MHz, so that the phase change of the interferometer output is precisely measured with a displacement resolution of 0.1 nanometer without significant loss of dynamic bandwidth. A thermal control scheme is adopted to stabilize the cavity length with aims to suppress frequency drifts caused by the phenomena of frequency pulling and polarization anisotropy of the two-axial mode laser to a stability level of 2 parts in $10^9$. The two-axial mode HeNe laser yields a high output power of 2.0 mW, whlch allows us to perform multiple measurements of up to 10 machine axes simultaneously.

• Journal of Welding and Joining
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• 제17권3호
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• pp.66-70
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• 1999

In order to investigate the quantitative behavior of galvanic corrosion in weld joints between stainless std이 and carbon steel, electrochemical polarization experiments were performed at pH4, pH7 and pH10 with boric acid concentration 4000ppm, and water temperature were selected as $35^{\circ}$C and $60^{\circ}$C. As the results, the galvanic corrosion phenomena of carbon steel weld material at $60^{\circ}$C was revealed $2{1\over2}$ times higher corrosion rate than that at $35^{\circ}$C condition. The corrosion rate of stainless steel was almost inedependent of the variation of pH. The significant corrosion rates of carbon steel and the weld joint of carbon-carbon steel were observed at pH 4.

• Membrane and Water Treatment
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• 제7권2호
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• pp.127-141
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• 2016

Electrodialysis (ED) is known to be a useful membrane process for desalination, concentration, separation, and purification in many fields. In this process, it is desirable to work at high current density in order to achieve fast desalination with the lowest possible effective membrane area. In practice, however, operating currents are restricted by the occurrence of concentration polarization phenomena. Many studies showed the occurrence of a limiting current density (LCD). The limiting current density in the electrodialysis process is an important parameter which determines the electrical resistance and the current utilization. Therefore, its reliable determination is required for designing an efficient electrodialysis plant. The purpose of this study is the development of a predictive model of the limiting current density in an electrodialysis process using response surface methodology (RSM). A two-factor central composite design (CCD) of RSM was used to analyze the effect of operation conditions (the initial salt concentration (C) and the linear flow velocity of solution to be treated (u)) on the limiting current density and to establish a regression model. All experiments were carried out on synthetic brackish water solutions using a laboratory scale electrodialysis cell. The limiting current density for each experiment was determined using the Cowan-Brown method. A suitable regression model for predicting LCD within the ranges of variables used was developed based on experimental results. The proposed mathematical quadratic model was simple. Its quality was evaluated by regression analysis and by the Analysis Of Variance, popularly known as the ANOVA.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.784-789
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• 2012

본 논문에서는 방식 대상물 주변에 설치되어 있는 다수의 양극과 기준전극을 감시하고, 상황에 맞게 고정전위 및 분극 방법을 자동으로 적용할 수 있는 시스템을 개발하였다. 특히, 개발된 시스템은 방식 대상물의 전 부분이 균일하게 방식이 이루어지도록 자동 조정하는 기능을 가진 원격 전기방식 자동제어 장치, 부식전위를 검출하는 기능을 수행하는 부식감시 장치 그리고 이들 장치의 부식 및 방식 관련 데이터에 대해 실시간 감시 및 제어와 예측 기능을 수행하는 웹기반 운영프로그램으로 구성하였으며, 이 시스템을 이용하여 산화현상에 의한 부식을 방지함으로써 방식 대상물의 수명을 최대화할 수 있다.

• 조명전기설비학회논문지
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• 제30권2호
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• pp.93-101
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• 2016

This paper presents the surface discharge characteristics in Dry-Air on laminated epoxy solid dielectrics and conductive particles in order to provide the valuable information for the insulation design of eco- friendly gas insulated switchgear. To improve insulation performance, the three types of the laminated epoxy solid dielectrics were proposed, and it was revealed that their surface discharge characteristics were similar to the bakelite dielectrics of same-laminated types. From the surface discharge characteristics of dry air, it was demonstrated that the effect of conductive particles on surface discharge voltage was dominant when there are this particles at the shortest electrode gap and that the degradation of insulation performance on the conductive particles was evident in epoxy than teflon. These phenomena were interpreted in terms of particle-triggered discharge mechanism and electric field of triple junction, respectively.

• 복식
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• 제59권3호
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• pp.27-41
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• 2009

Interpreting the phenomenon of Fast fashion that is prevalent these days, this research is meaningful in that it prepares the frame which suggests the vision to read the trend of 2000s and analyzes the property of phenomenon of Fast Fashion in the connection with society and culture. The so[io-cultural property can be largely characterized by consumption orientation, change orientation, efficiency, moment and multiculturism. Analyzing the phenomenon of fast fashion that emerged after 2000 on the basis of such sociocultural background, it is largely classified into imitation, fashionability, disposability, portability, transformation and convergence. Due to the hi-polarization of consumption, people tend to select imitated goods, and people accustomed to speed get interested in the fashionability of all Phenomena. Further, society that is transient and changing rapidly makes the habit of purchasing in disposability. The property of nomad society encourages to keep the habit of portability. Such change-oriented society and rapidly changing life pattern make them adapt in diverse transformation modes of Fast Fashion. Further, multi-cultural world integrates enterprises through combination of all cultures and the convergence of all factors.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.69-75
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• 1999

The characteristics of $H_2$ gas detection have been investigated using the Pt-MIS capacitor composed of the LPCVD nitride on the oxide. The flat band voltage shift is measured as 0.1 V in 1,000 ppm $H_2$ gas ambient and to be independent of Pt catalyst thickness. It is found that the flatband voltage shift is proportional to the hydrogen concentrations. The response and recovery time of Pt-MIS capacitor are 5 mins and 25 mins respectively. The samples of 30nm thick Pt revealed much higher sensitivity than that of 150nm samples. The samples of 150nm Pt showed that the flatband voltage shift of the device is due to the formation of the dipole layer of the adsorbed hydrogen atoms at the Pt-insulator interface.

• 전자공학회논문지A
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• 제33A권10호
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• pp.90-97
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• 1996

A numerical method for scattering of electromagnetic waves from a periodic strip grating over a grounded dielectric slab is considered for TE and TM polarization cases from the viewpoints of both reflection grating problem and leaky wave antenna problem. The analysis is based on a mode expansion method, floquet's theorem, and the method of moments. Numerical results involving some combinations of geometric parameters are presented in terms of complex propagation constant (kd-$\beta$d diagram), radiation pattern, and relative scattered powers of spectral modes. In particular, the relationship between complex propagatio constnat form the viewpoint of leaky wqve antenna problem and Off-bragg and bragg blazing phenomena from the viewpoint of reflecton graing problem is investigated.

• 한국자기학회지
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• 제7권6호
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• pp.285-292
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• 1997

Cobalt ferrite와 Pb(Zr, Ti) $O_{3}$ 복합체를 고상 반응법으로 제조하여, magnetoelectric 효과를 조사하였다. 소결 시간과 cobalt ferrite의 부피비가 증가함에 따라 magnetoelectric 전압 계수의 최대값이 증가하였다. 한편, 이 최댜값을 나타내는 자기장은 소결 시간 증가에 따라 낮은 쪽으로, cobalt ferrite 부피 증가에 따라 높은 쪽으로 이동하였다. 이러한 현상들은 각 상의 입자 크기 변화와 이에 따른 응력 전달 변화, 자화 및 분극 용이도로 설명되었다. 비화학당량 조성인 $Co_{1.02}$F $e_{1.98}$ $O_{4}$를 사용하여, 이제까지 발표된 최대 효과보다 약 30% 높은 0.174 V/cm Oe 의 magnetoelectric 전압 계수 값을 얻었다.얻었다.