• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
• /
• pp.145-148
• /
• 2006

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권1호
• /
• pp.9-15
• /
• 2013

지구 온난화 현상과 유가급등에 따른 에너지 부족 현상은 생산된 에너지의 효율적인 사용과 관리 문제를 부각시켰다. 이에 열교환기의 에너지 효율 향상을 위한 새로운 방안이 요구되었고 새로운 작동유체로서 나노유체의 열전달 특성 연구가 필요한 실정이다. 나노유체의 전도열전달특성의 경우 많은 선행연구에서 예측 가능한 패턴을 보이며 증가한 반면, 대류열전달 특성의 경우 특성이 명확하지 않아 추가적인 연구가 필요한 실정이다. 본 연구에서는 $25^{\circ}C$, $50^{\circ}C$의 입구온도 조건에서 레이놀즈수와 나노유체의 vol%를 증가시키며 실험을 수행하였다. 수행 결과 레이놀즈수와 vol%, 입구 온도가 증가할수록 대류열전달계수가 향상되었다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.534-537
• /
• 2008

Growing attention has been given to sterilizing and antibacterial effects of nano-silver, recently. Nano-silver solution can be applied to the heat exchanger in an air conditioner to prevent bad smell or bacteria. The present study is directed at the nozzle spray characteristics over a heat exchanger. This problem is of particular interest in the design of a nano-silver HVAC system. The effects of nozzle position and flow rate on the spray area over a horizontal surface have been investigated for various nozzles. The results obtained indicate that spray area is increased as the height of spray position is increased or mass flow rate is increased. The wetted area over a practical heat exchanger is also studied at a given nozzle height. It is found that the wetted area is gradually increased with an increase in the flow rate. However, the effect of flow rate on the wetted area is a little affected by flow rate in the range of too much flow rate. It is also found that the wetted area is decreased as the inclination angle of a heat exchanger is increased.

• 한국표면공학회지
• /
• 제41권5호
• /
• pp.226-231
• /
• 2008

Titanium and its alloy have been widely used in dental implant and orthopedic prostheses. Electrochemical characteristics of dental implant in the various simulated body fluids have been researched by using electrochemical methods. Ti-6Al-4V alloy implant was used for corrosion test in 0.9% NaCl, artificial saliva and simulated body fluids. The surface morphology was observed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The electrochemical stability was investigated using potentiosat (EG&G Co, 263A). The corrosion surface was observed using scanning electron microscopy (SEM). From the results of potentiodynamic test in various solution, the current density of implant tested in SBF and AS solution was lower than that of implant tested in 0.9% NaCl solution. From the results of passive film stability test, the variation of current density at constant 250 mV showed the consistent with time in the case of implant tested in SBF and AS solution, whereas, the current density at constant 250mV in the case of implant tested in 0.9% NaCl solution showed higher compared to SBF and AS solution as time increased. From the results of cyclic potentiodynamic test, the pitting potential and |$E_{pit}\;-\;E_{corr}$| of implant tested in SBF and AS solution were higher than those of implant tested in 0.9% NaCl solution.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권3호
• /
• pp.879-894
• /
• 2016

In micro-fluid systems, fluids are injected into extremely narrow polymer channels in small amounts such as micro-, nano-, or pico-liter scales. These channels themselves are embedded on tiny chips. Various specialized structures in the chips including pumps, valves, and channels allow the chips to accept different types of fluids to be entered the channel and along with flowing through the channels, exert their effects in the framework of different reactions. The chips are generally crystal, silicon, or elastomer in texture. These highly organized structures are equipped with discharging channels through which products as well as wastes of the reactions are secreted out. A particular advantage regarding the use of fluids in micro-scales over macro-scales lies in the fact that these fluids are much better processed in the chips when they applied as micro-scales. When the laboratory is miniaturized as a microchip and solutions are injected on a micro-scale, this combination makes a specialized construction referred to as "lab-on-chip". Taken together, micro-fluids are among the novel technologies which further than declining the costs; enhancing the test repeatability, sensitivity, accuracy, and speed; are emerged as widespread technology in laboratory diagnosis. They can be utilized for monitoring a wide spectrum of biological disorders including different types of cancers. When these microchips are used for cancer monitoring, circulatory tumor cells play a fundamental role.

• KSTLE International Journal
• /
• 제6권1호
• /
• pp.28-32
• /
• 2005

The electrorheoloRical (ER) fluids are composed of a colloidal dispersion of polarizable particles in insulating oil, and it's the rheological property changes by the applied electric field. These changed are reversible and occur fast within a fewmilliseconds. The ER properties of the ER fluid such as increment of viscosity and yield stress come from the particle chain structure induced by electric fleld. When formulating the ER fluid for a speciflc application, some requirement must besatisfled, which are high yield stress under electric field, rapid response, and dispersion stability. While this characteristic makes valuable ER fluids in valious industrial applications, their lung term and quiescent application has been limited because ofproblems with particle sedimentation. In an effort to overcome sedimentation problem of ER fluids, the anhydrous ER materials of monodispersed hollow polyaniline (PANI) and adipate derivative respectively with submicron-sized suspension providing wide operating temperature range and other advantage were synthesized in a four-step procedure. The ER fluidswere characterized by FT-lR, TGA, DLS, SEM, and TEM. Stability of the suspensions was examined by an UV spectroscopy.The rheological and electrical properties of the suspension were investigated Couette-type rheometer with a high voltagegenerator, current density, and conductivity. And the behavior of ER suspensions was observed by a video camera attached toan optical microscope under 3kV/mm. The suspensions showed good ER properties, durability, and particle dispersion.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2009년도 춘계학술대회 논문집
• /
• pp.78-83
• /
• 2009

In general, Light-hardening polymer was used UV nanoimprint technology. A light-hardening polymer was had the problem of poor hardness, durability. In order to overcome the problem of polymer, inter change optical glass. However glass is very manufacture and a lowering of standars transmittance. In order to glass recover was necessary polishing process. The process is magnetorheological fluids polishing. MR polishing has been developed as a new precision finishing technique to obtain a fine surface. Hence, Magnetorheological fluids has been used for micro polishing to get micro parts. This polishing process guarantees high polishing quality by controlling the fluid density electrically. The applied material in experiments is fused silica glass. Fused silica glass is widely used in the optical field because of high degree of purity. For MR polishing experiments, MR fluid was composed with DI-water, carbonyl iron and nano slurry ceria. The wheel speed and electric current were chosen as the variables for analyzing the characteristics of MR polishing process. Outstanding surface roughness of Ra=1.58nm was obtained on the fused silica glass specimen. And originally glass transmittance was recover on the fused silica glass.

• 공업화학
• /
• 제16권2호
• /
• pp.169-179
• /
• 2005

다공성 소재는 바이오 및 전기전자소재 등 다양한 분야에 폭넓게 응용될 수 있다. 이러한 가공소재의 제조 및 공정은 주로 유기용매의 사용에 의해 이루어지고 있으나 유기용매는 대기 방출과 같은 많은 환경성 문제를 야기시키고 있다. 이에 반하여 초임계 유체는 기능성 기공 소재의 제조를 위한 대안 용매로서 수많은 물리적, 화학적 그리고 유독성 측면에서 유용한 장점을 보여주고 있다. 본 총설에서는 초임계 유체를 이용하여 나노/마크로 크기의 미세 기공구조 설계 및 형상 제어를 위한 공정 기술과 초임계 유체 내에서의 화학적 합성 반응을 통한 다공성 소재의 제조 기술을 소개하고자 한다.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 2004년도 Annual Meeting BioExibition International Symposium
• /
• pp.187-193
• /
• 2004

This paper covers the basic principles of the AFM and how these systems may be used to image biological materials and measure particle-surface interactions in process environments. e.g. visualize molecules and structure on surfaces in aqueous environments, measure forces of interaction of proteins and DNA, biosurface and cells. Examples of work include applications biological spore control agents control systems, process materials selection for example appropriate filters for biological processing, mechanical properties and bio-surface engineering.

• Toxicological Research
• /
• 제31권2호
• /
• pp.181-189
• /
• 2015

In recent years, the use of both nano- and micro-sized lanthanum has been increasing in the production of optical glasses, batteries, alloys, etc. However, a hazard assessment has not been performed to determine the degree of toxicity of lanthanum. Therefore, the purpose of this study was to identify the toxicity of both nano- and micro-sized lanthanum oxide in cultured cells and rats. After identifying the size and the morphology of lanthanum oxides, the toxicity of two different sized lanthanum oxides was compared in cultured RAW264.7 cells and A549 cells. The toxicity of the lanthanum oxides was also analyzed using rats. The half maximal inhibitory concentrations of micro-$La_2O_3$ in the RAW264.7 cells, with and without sonication, were 17.3 and 12.7 times higher than those of nano-$La_2O_3$, respectively. Similar to the RAW264.7 cells, the toxicity of nano-$La_2O_3$ was stronger than that of micro-$La_2O_3$ in the A549 cells. We found that nano-$La_2O_3$ was absorbed in the lungs more and was eliminated more slowly than micro-$La_2O_3$. At a dosage that did not affect the body weight, numbers of leukocytes, and concentrations of lactate dehydrogenase and albumin in the bronchoalveolar lavage (BAL) fluids, the weight of the lungs increased. Inflammatory effects on BAL decreased over time, but lung weight increased and the proteinosis of the lung became severe over time. The effects of particle size on the toxicity of lanthanum oxides in rats were less than in the cultured cells. In conclusion, smaller lanthanum oxides were more toxic in the cultured cells, and sonication decreased their size and increased their toxicity. The smaller-sized lanthanum was absorbed more into the lungs and caused more toxicity in the lungs. The histopathological symptoms caused by lanthanum oxide in the lungs did not go away and continued to worsen until 13 weeks after the initial exposure.