• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.937-942
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• 1995

Great interest has prompted Boron Neutron Capture Therapy (BNCT) as a new treatment for brain tumors. The use of $^{252}$Cf as a neutron source for BNn makes the in-hospital treatments of tumors to be possible. Newly proposed subcritical multiplying assemblies (SMA) are explored to improve relatively tow neutron fluxes of the source and construct the feasibilities of $^{252}$Cf as a neutron source. The MCNP code has been used to evaluate the effective multiplication factor of the entire system and the intensities and percentages of epithermal neutron flux at the patient-end surface of the system. The neutron beam using SMA shows the epithermal neutron flux enhancement of about 13 times as large as the beam without using SMA. It is expected that the neutron beam proposed in this research will be more effective for treatment of tumors due to the increased therapeutic neutron fluxes.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.335-346
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• 2013

The Critical Heat Flux (CHF) of water with dispersed alumina nanoparticles was measured for the geometry and flow conditions relevant to the In-Vessel Retention (IVR) situation which can occur during core melting sequences in certain advanced Light Water Reactors (LWRs). CHF measurements were conducted in a flow boiling loop featuring a test section designed to be thermal-hydraulically similar to the vessel/insulation gap in the Westinghouse AP1000 plant. The effects of orientation angle, pressure, mass flux, fluid type, boiling time, surface material, and surface state were investigated. Results for water-based nanofluids with alumina nanoparticles (0.001% by volume) on stainless steel surface indicate an average 70% CHF enhancement with a range of 17% to 108% depending on the specific flow conditions expected for IVR. Experiments also indicate that only about thirty minutes of boiling time (which drives nanoparticle deposition) are needed to obtain substantial CHF enhancement with nanofluids.

• Journal of Mechanical Science and Technology
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• 제14권9호
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• pp.997-1004
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• 2000

The experiments were conducted by using water and paraffin slurry to investigate the effect of a chip spacing in the multichip module on the cooling characteristics from an in-line $4{\times}3$ array of discrete heat sources which were flush mounted on the top wall of a channel. The experimental parameters were chip spacing in a multichip module, heat flux of simulated VLSI chip, mass fraction of paraffin slurry, and channel Reynolds number. The removable heat flux at the same chip surface temperature decreased as the chip spacing decreased at the first and fourth rows. The local heat transfer coefficients for the paraffin slurry were larger than those for water, and the chip spacing on the local heat transfer coefficients for paraffin slurry influenced less than that for water. The enhancement factor for paraffin slurry showed the largest value at a mass fraction of 5% regardless of the chip spacing, and the enhancement factors increased as the chip spacing decreased. This means that the paraffin slurry is more effective than water for cooling of the highly integrated multichip module.

• 설비공학논문집
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• 제13권7호
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• pp.602-611
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• 2001

Experiments on the condensation heat transfer characteristics inside a smooth and a microfin tube with R410A/R22 are performed in this study. The test tubes 7/9.52 mm in outside diameters and 3m in length are used. Varying the mass flux of the refrigerant and the condensation temperatures, the average heat transfer coefficients and pressure drop are investigated. Most flows in this study are in the annular and/or wavy flow regime. It is shown that the heat transfer is enhanced and the pressure drops are larger in the microfin tube than the smooth tube. From the heat transfer enhancement coefficients and the pressure drops, it is found that the high heat transfer enhancement factors are obtained in the range of small mass flux while the penalty factors are almost equal. Experiments results show that average heat transfer coefficients of R410A is larger than that of R22 and pressure drop of R410A is less than R22.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2006년도 High Temperature Superconductivity Vol.XVI
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• pp.13-13
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• 2006

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2004년도 춘계총회 및 연구발표회 초록집
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• pp.37.2-37.2
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• 2004

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.251-252
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• 2009

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.280-281
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• 2005

We have studied the superconducting properties and flux pinning enhancement of $(Y_{0.5}Nd_{0.25}Sm_{0.25})_{1.8}Ba_{2.4}Cu_{3.4}O_y$ [(YNS)-1.8] composite oxides by melt growth process in air. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.5}Nd_{0.25}Sm_{0.25})_2BaCuO_5$ [(YNS)211] nonsuperconducting particles were uniformly dispersed in large (YNS)123 superconducting matrix. The sample showed a sharp superconducting transition at 91 K. The magnetization measurements of the (YSN)-1.8 sample exhibited the enhanced flux pinning, compared with $YBa_2Cu_3O_y$ (Y-123) sample without Sm and Nd.

• 대한환경공학회지
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• 제28권2호
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• pp.197-206
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• 2006

본 연구에서는 최근 매립지 침출수 처리를 위해 많이 활용되고 있는 막분리 공정에 초음파를 적용하여 투과속도와 막의 세정효율 향상에 미치는 영향인자와 효과에 대하여 살펴보았다. 즉, 중공사 형태의 MF막과 관형의 UF막을 대상으로 초음파의 주파수($40{\sim}120$ kHz), 초음파의 세기($200{\sim}500$ W), 운전압력($0.1{\sim}2.3kg/cm^2$), 초음파 조사시간 등을 변화시키며 투과속도 향상에 미치는 영향을 평가하였다. 1차 처리된 침출수를 이용하여 초기 50 min 동안 막을 오염시킨 다음 70 min 동안 초음파를 조사하여 조사기간과 투과속도의 변화를 관찰하였다. 순수의 투과속도에 대한 투과속도의 회복률(recovery ratio)과 세정직전의 투과속도에 대한 초음파 조사 후 투과속도의 상승률(enhancement ratio)을 이용하여 영향인자를 분석하였다. 동일한 조건에서 막의 초음파 세정에 의한 투과속도 개선 효과는 주파수에 반비례적이며. 초음파의 조사강도에 비례적으로 나타났고, 막의 운전압력이 높으면 세정효과가 지연되며 투과속도의 개선효과도 감소하였다. 또한 10,000과 100,000 MWCO의 UF막에서의 회복율과 상승률은 각각 최대 75-98%와 40-50% 이었으나, $0.1{\mu}m$ MF막에서는 각각 10%와 500%였다. 1차 처리 침출수를 이용한 실험결과로부터 초음파에 의해 발생되는 기계적 진동을 활용한 막세정이 기존의 수세정과 약품세정 대신에 활용가능성이 확인되었다.

• Journal of Pharmaceutical Investigation
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• 제38권6호
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• pp.373-380
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• 2008

In order to develop optimal formulation and iontophoresis condition for the transdermal delivery of levodopa, we have evaluated the effect of two permeation enhancers, ethanol and oleic acid in microemulsion, on transdermal delivery of levodopa. In vitro flux studies were performed at $33^{\circ}C$, using side-by-side diffusion cell and full thickness hairless mouse skin. Current density applied was $0.4\;mA/cm^2$ and current was off after 6 hours application. Levodopa was analysed by HPLC at 280 nm. The o/w microemulsions of oleic acid in buffer solution (pH 2.5 & 4.5) were prepared using oleic acid, Tween 80 and ethanol. The existence of microemulsion regions were investigated in pseudo-ternary phase diagrams. Contrary to our expectation, cumulative amount of levodopa transported from microemulsion (pH 2.5) for 10 hours was similar to that from aqueous solution in all delivery methods (passive, anodal and cathodal). When pH of the micro-emulsion was pH 4.5, cumulative amount of levodopa transported for 10 hours increased about 40% (anodal) to 50% (cathodal), when compared to that from aqueous solution. Flux from pH 4.5 microemulsion showed higher value than that from pH 2.5 in all delivery methods. These results seem to indicate that electroosmosis plays more dominant role than electrorepulsion in the flux of levodopa at pH 2.5. The effect of ethanol on iontophoretic flux was studied using pH 2.5 phosphate buffer solution containing 3% or 5% (v/v) ethanol. Flux enhancement was observed in passive and anodal delivery as the concentration of the ethanol increased. Without ethanol, cathodal delivery showed higher flux than anodal delivery. Anodal delivery increased the cumulative amount of levodopa transported 1.6 fold by 5% ethanol after 10 hours. However, in cathodal delivery, no flux enhancement of levodopa was observed during current application and only marginal increase in cumulative amount transported after 10 hours was observed by 5% ethanol. These results seem to be related to the decrease in dielectric constant of the medium and the lipid extraction of the ethanol, which decrease the electroosmotic flow, and thus decrease the flux. Overall, the results provide important insights into the role of electroosmosis and electrorepulsion in the transport of levodopa through skin, and provide some useful informations for optimal formulation for levodopa.