• Journal of Magnetics
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• 제2권3호
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• pp.86-92
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• 1997

An artificially modulated magnetic Co/Pd multilayer is one of the promising candidates for high density magneto-optic (MO) recording media in the wavelength of a blue laser beam, due to large Kerr rotation angle. However, since the Co/Pd multilayer is a non-equilibrium state in terms of free energy and MO recording is a kind of thermal recording which is conducted around Curie temperature (Tc) of the recording media, the assessment of the thermal stability in the Co/Pd multilayer is crucially important both for basic research and applications. As the parameter of the thermal stability in this research, effective interdiffusion coefficients (Deff) perpendicular to the interface of the Co/Pd multilayers are measured in terms of Ar sputtering pressure and heat treatment temperature. From the results of the research, we find out that the magnetic exchange energy between Co and Pd sublayers strongly affects Deff of the Co/Pd multilayers. This discovery will provide the understanding of the magnetic exchange energy in the effective interdiffusion process of a magnetic multilayer structure and suggest the operating temperature range for MO recording in the Co/Pd multilayer for the basic research and applications, respectively.

• 대한기계학회논문집B
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• 제25권3호
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• pp.422-432
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• 2001

An analytical characterization is presented on the transient heat transfer by an oscillating flow through a porous slab. Based on a two-equation model, analytic solutions are obtained for both the fluid and solid temperature variations. Two parameters are identified as the Stanton number for the internal heat exchange and the ratio of the thermal capacities between the solid and fluid phases. The heat transfer characteristics are shown to be classified into four regimes according to the two parameters and physical interpretation is presented on the particular heat transfer processes within each regime. In addition, the condition for the local thermal equilibrium between the phases is examined and the relevant criterion is suggested.

• 한국광학회지
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• 제12권5호
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• pp.394-400
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• 2001

다층 박막에서의 빛의 반사와 흡수 및 열전달 방정식을 수치해석적으로 풀어 광기록매체용 다층 박막의 광학적 특성과 열전달 특성을 알아보고 이 두 특성들을 모두 고려하여 광기록에 적합한 레이저의 출력 및 지속시간, 다층 박막 구조 상수를 제시하였다. 그 결과 레이저는 650 nm 파장을 기준으로 출력 18mW, 지속 시간 60 nm가 적당하였으며 박막 구조 상수는 ZnS-SiO$_2$140nm, Ge-Sb-Te 20 nm, ZnS-SiO$_2$20~30nm, Al-alloy 100~150 nm가 적당하였다.

• 한국재료학회지
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• 제29권4호
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• pp.264-270
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• 2019

As a case study on aspect ratio behavior, Kaolin, zeolite, $TiO_2$, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ${\sim}6{\mu}m$ are shifted to submicron size, D50 ${\sim}0.6{\mu}m$, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.490-499
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• 1998

This study was initiated to investigate the applicability of sludge from water or waste water treatment on the crop cultivation. Sludge is generated in the process of water and wastewater treatment process in large quantity. The sludge can cause many environmental problems. we have a many available treatment methods of sludge However, these methods still shortcomings and are not. The composition of typical municipal sludge contains organics and inorganics. The organics components are normally burnt in high temperature and mainly inorganics components are left after thermal treatment process. For the production of artificial media, chabazite was used as additive, and the mixed material was thermally treated in the firing kiln at 800~1,10$0^{\circ}C$ for about 10 minutes. The physical and chemical characteristics of artificial media were analyzed and it showed that the artificial media could be used as a media for plants and soil conditioner for farmland. The concentrations of the toxic heavy metals in the media were lower then those in the soil quality standard for farmland. This study illustrated that the artificial media production process, and introduced how to produce it's possible application as a media for Plant growth.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.115.2-115.2
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• 2007

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.263-264
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• 2004

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 춘계연구발표회 논문개요집
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• pp.158-159
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• 2002

• 한국지반공학회논문집
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• 제33권2호
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• pp.35-47
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• 2017

지반의 열적 거동은 대부분 열전도에 국한되어 연구가 진행되었으며, 자연대류 현상에 대한 연구는 매우 미비한 실정이다. 지반의 온도증가는 간극수의 밀도변화에 따른 부력을 유발하여 자연대류를 발생시키게 된다. 유체역학 관점에서 다공질 재료내의 자연대류 해석의 제약조건에 대하여 논의하고, 거시적 관점에서 완전 결합된 열-수리-역학적인 지배방정식을 이용한 대류현상에 대한 수치해석 기법을 제시하였다. 실내 열전도도 측정을 위한 탐침기 실험에 대한 수치실험은 자연대류를 무시하고 평가된 열전도도의 불확실성에 대하여 논의하고, 모델식과의 오류를 최소화하기 위한 적정한 실험조건을 제시하였다. 해저 전력선의 매설은 해저면 0.2m 깊이에서의 온도상승을 $2^{\circ}C$로 제한하고 있으나, 투수성이 큰 지반재료에 대한 수치해석결과는 기준온도를 초과하는 것으로 나타났다. 해저면의 온도와 열-수리-역학적 물성은 전력선의 매설설계에 중요한 설계인자이며 자연대류의 영향을 고려하여야 한다. 특히, 큰 투수성을 갖는 지반내에 열원이 존재하는 경우, 간극수의 밀도변화에 따른 자연대류가 중요한 열전달의 인자가 되므로 이를 고려한 해석을 수행하여야 한다.

• 한국분말재료학회지
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• 제4권3호
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• pp.179-187
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• 1997

Milling media of steel and zirconia were used to produce $MoSi_2$ by mechanical alloying (MA) of Mo and Si powders. The effect of milling media on MA of Mo-65.8at%Si powder mixture has been investigated by SEM, XRD, DTh and in-situ thermal analysis. The powders mechanically alloyed by milling medium of steel for 8 hours showed the structure of fine mixture of Mo and Si, and those mechanically alloyed by milling medium of zirconia for longer milling time showed the structure of fine mixture of Mo and Si. The tetragonal $\alpha$-$MoSi_2$ Phase and the tetragonal $Mo_5Si_3$ phase appeared with small Mo peaks in the powders milled by milling medium of steel for 4 and 8 hours. The $\alpha$-$MoSi_2$ phase and the hexagonal $\beta$-$MoSi_2$ phase were formed after longer milling time. The $\alpha$-$MoSi_2$ phase appeared with large Mo peaks in the powders milled by milling medium of zirconia for 4 hours. The phases, $\alpha$-$MoSi_2$ and $\beta$-$MoSi_2$. were formed in the powders milled for longer milling time. DTA and annealing results showed that Mo and Si were transformed into $\alpha$-$MoSi_2$ and $Mo_5Si_3$, while $\beta$-$MoSi_2$ into $\alpha$-$MoSi_2$. In-situ thermal analysis results demonstrated that there were a sudden temperature rise at 212 min and a gradual increase in temperature in case of milling media of steel and zirconia, respectively. The results indicate that MA can be influenced by materials of milling medium which can give either impact energy on powders or thermal energy accumulated in vial.