• Membrane Journal
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• v.26 no.3
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• pp.187-196
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• 2016

Pressure-assisted forward osmosis (PAFO) process has recently been under spotlight for its potential to improve forward osmosis (FO) process performance by applying low hydraulic pressure on the feed side. Structure parameter, one of the governing factors in estimating water flux and solute flux across FO membranes in the solution-diffusion model (S-D model), determines solute resistivity in FO and PAFO processes. This study aims to estimate the trend of structure parameter change with respect to varying additional hydraulic pressure condition in PAFO.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.15-20
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• 1999

Elevated temperature static fatigue behavior of silicon has been investigated by stress intensity/life test method. Static fatigue crack growth rate increase with the increase of temperature. Such tendency is found to be mainly related to the decrease of fracture toughness with the increase of temperature. That is, when static fatigue crack growth rate, da/dt is expressed by da/dt=AK1m, a constant A is a function of fracture toughness Kc and the exponent m is a constant which is independent of temperature or Kc. However, in the case of high temperature that glass phase is softened, the crack growth rate is found to be deviated from the above relation. This reason is, thus, discussed.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.141-143
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• 2018

본 논문은 계통연계형 인버터의 단독운전 방지를 위해 정궤환을 이용한 무효전력 변동기법을 제안하였으며, 구현 및 실험을 통해 단독운전 방지 성능을 검증하였다. PCC 지점에는 양호도($Q_f$) 2.5의 특성을 갖는 3상 RLC 부하가 연결되며, 부하 공진주파수는 60Hz로 설정하였다. 무효전력 변동기법은 일정 크기로 주입되는 무효분과 주파수 편차를 이용한 정궤환으로부터 공급되는 무효분으로 구성된다. 계통연계 운전 시에는 일정한 무효전력 성분만이 공급되며 역률은 0.9975이다. 단독운전 발생 시, 일정 무효전력 때문에 변화된 PCC 주파수와 계통 정격주파수 간의 편차는 정궤환 성분을 활성화하고, 증가된 무효전력에 의한 PCC 주파수 변화를 검출하여 단독운전을 판단한다. 1.7kW 3레벨 T-타입 인버터를 통해 단독운전 방지 성능을 실험하였으며, 검출시간은 각각 53ms, 150ms로써 우수한 성능을 검증하였다.

• Honam Mathematical Journal
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• v.1 no.1
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• pp.1-9
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• 1979

Positive Local Coordmate($(x^1,x^2,{\cdots}x^n)$)을 갖는 Oriented Manifold M을 생각한다. M이 Compact Carrier를 갖는 경우, M위의 n차(次) Differential Form ${\phi}^{(n)}$의 적분(積分)을 $${\int}{\phi}^{(n)}=\sum_{\alpha}{\int}_{-{\infty}}^{\infty}{\cdots}{\int}_{-{\infty}}^{\infty}f_{\alpha}{\phi}^{(n)}dx^1{\cdots}dx^n$$로 정의(定義)하며 (정의(定義) 7), M위의 p 차(次)의 Differential form $\beta^{(p)}$와 Differential simplex $S^{(p)}=(S^{(p)},\;{\pi},\;{\varepsilon})$에 대하여 $S^{(p)}$위의 $\beta^{(p)}$의 적분(積分)을 $${\int}_{^{(p)}S}{\beta}^{(p)}={\int}_{S^{(p)}}{\varepsilon}{\pi}^*{\beta}^{(p)}={\int}_{E^p}f{\cdot}{\varepsilon}{\cdot}{\pi}^*{\beta}^{(p)}$$로 정의(定義)한다 (정의(定義) 9). 단(但) $\bar{S}^{(p)}$는 $S^{(p)}=(p_0{\cdot}p_1{\cdots}p_p)$에 의(依)하여 Spanning 되는 $E^p$의 Subspace이고 f는 $\bar{S}^{(p)}$의 특성함수(特性函數)이다. 이때 (n-1)차(次)의 Differential Form ${\beta}^{(n-1)}$이 Compart인 Carrier를 가지면 ${\int}d{\beta}^{(n-1)}=0$이 됨을 고찰(考察)하며(정리(定理 8), (p-1)차(次) Differential Form ${\beta}^{(p-1)$과 p차(次) Differential Chain $C^{(p)}$에 관(關)하여 $${\int}_{C^{(p)}}d{\beta}^{(p-1)}={\int}_{{\partial}C^{(p)}}{\beta}^{(p-1)}$$이 성립(成立)함을 구명(究明)하려 한다(정리(定理) 10).

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.259-264
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• 2007

This paper describes the mathematical modeling method for the static magnetic field signature generated by a magnetic scale model. we proposed the equivalent dipole modeling method utilizing a singular value decomposition technique from magnetic field signatures by magnetic sensors are located special depths below the scale model. The proposed dipole modeling method was successfully verified through comparisons with the real measured values in our non-magnetic laboratory. Using the proposed method, it is possible to predict and analyze static magnetic field distributions at any difference depths generated from the real ships as well as a scale model ship.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.2
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• pp.36-46
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• 1984

The Ga1-xInxSe single crystals for 0.0 < x < 0.1 and 0.8 < 1.0 were grown by the Bridgman method. The crystal structure of Ga1-xInxSe is found to be hexagonal for 0.0 < X < 1.0. The Ga1-xInxSesingle crystals have indirect energy gap with a temperature coefficient dEg/dT= -(2.4 - 4.3) $\times$ 10-4 eV/K in the range 60-250K. The temperature dependence of the energy gap can be explained by the electron-Phonos interaction model.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.286-291
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• 2000

$Cd_{1-x}Mn_{x}Te$ singe crystals were grown by the vertical Bridgman method and the Faraday rotations were measured as a function of wavelength and magnetic field. The Verdet constants were evaluated using the result of Faraday rotation. The Verdet constants were maximum at nearly absorption edge and increased for $0\leq x \leq 0.38 $ but decreased for x>0.40. We found that large Faraday rotation occur in $Cd_{0.62}Mn_{0.38}Te$ at nearly absorption edge wavelength was more useful for a magnetic field sensor than any other crystals, and $Cd_{0.60}Mn_{0.40}Te$ crystal was useful in this application when wavelength is He-Ne laser wavelength.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.279-285
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• 2000

High quality crystals of $YMnO_3$, which is interested in non-volatile memory device application, were grown by the floating zone method. Optimum condition for powder synthesis was established to be $1200^{\circ}C$ for 10 hrs and optimum condition for sintering of $YMnO_3$feed-rod was established to be $1500^{\circ}C$ for 10hrs respectively. It was found from non-seeded growth experiment that $YMnO_3$crystal was grown preferentially to the [1010] orientation. The $YMnO_3$single crystal, which was grown to the direction of perpendicular to C-axis, was typically 5mm in diameter, 50 mm in length and showed dark-blue color.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.207-215
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• 2010

This study was carried out for the purpose of obtaining the basic data for identifying the origin of amethyst. For this, the three dimensional shapes of inclusions contained in various amethyst were observed with Stereo Zoom microscope. The shape and chemical composition of cross section of solid inclusion and the chemical composition of evaporite were investigated by SEM-EDS. The evaporite is made from evaporating of liquid inclusion which is flowed out of amethyst sample by decompressing. Lastly, The trace mineral composition of amethyst was investigated by ICP-AES after digesting the amethyst sample with HF-$H_2SO_4$ solution.

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.183-190
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• 1996

Single crystals of ZnO were grown hydrothermally with KOH solution in silver lined autoclave. The effect of LiOH and NH4OH on the morphology of as-grown crystals was studied. As-grown crystals were pale green and the maximum size was 30×30×20mm3. Addition of LiOH reduced the density of flaws on the (0001) face of as-grown ZnO crystals. In highly concentrated KOH solution, ZnO had a strong tendency to grow along the c-axis. When 1.0-2.0 M of NH4OH was added into mineralizer, growth rate along the direction of a-axis increased. From this result, ZnO single crystals of equant-faced hexagonal prism could be grown with acicular seeds.