• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1712-1713
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• 2011

Inkjet technology have many merits in plenty of industrial applications. However, deposited droplet has a very critical issue that is coffee ring effect, for the application to an industrial manufacturing process. To remove the coffee ring effect, the effect of thermal treatment conditions on shapes of inkjet printed silver patterns were investigated in various surface condition. The surface changes were characterized by the contact angle measurement. Droplets from a 50 ${\mu}m$ nozzle were printed on the substrate after optimizing the ejection of individual droplets. Ink with a high boiling point of main solvent results in coffee ring effect. This result implies that the dominant factor that determines the shape of droplet is the drying conditions of main solvent of silver nanoparticle colloidal ink. As a results, selecting a proper thermal treatment conditions is very crucial for better shapes of inkjet printed silver nanoparticle colloidal patterns.

• 한국환경과학회지
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• 제31권9호
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• pp.781-791
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• 2022

In order to investigate the characteristics of the effects of various emission sources such as ships around the Busan North Port area, PM_2.5 samples were analyzed by SEM/EDS (scanning electron microscopy with energy dispersive x-ray spectrometer). In the port city Busan, the main emission source of PM_2.5 is ships, and soot was observed as the main exhaust particles of a ship diesel engine. As a result of the individual particle analysis of PM_2.5 at the sampling site, carbonaceous particles such as soot and water droplet-shaped, which are considered to be exhausted from ships, were constantly observed. And some spherical Fe-rich particles also appeared.

• 한국재료학회지
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• 제21권2호
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• pp.89-94
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• 2011

In this work, fabrication and electrochemical analysis of an individual multi-walled carbon nanotube (MWNT) electrode are carried out to confirm the applicability of electrochemical sensing. The reactive ion etching (RIE) process is performed to obtain sensitive MWNT electrodes. In order to characterize the electrochemical properties, an individual MWNT is cut by RIE under oxygen atmosphere into two segments with a small gap: one segment is applied to the working electrode and the other is used as a counter electrode. Electrical contacts are provided by nanolithography to the two MWNT electrodes. Dopamine is specially selected as an analytical molecule for electrochemical detection using the MWNT electrode. Using a quasi-Ag/AgCl reference electrode, which was fabricated by us, the nanoelectrodes are subjected to cyclic voltammetry inside a $2{\mu}L$ droplet of dopamine solution. In the experiment, RIE power is found to be a more effective parameter to cut an individual MWNT and to generate "broken" open state, which shows good electrochemical performance, at the end of the MWNT segments. It is found that the pico-molar level concentration of analytical molecules can be determined by an MWNT electrode. We believe that the MWNT electrode fabricated and treated by RIE has the potential for use in high-sensitivity electrochemical measurement and that the proposed scheme can contribute to device miniaturization.

• Asian Journal of Atmospheric Environment
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• 제7권3호
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• pp.161-168
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• 2013

In this study, an investigation was conducted to assess the washout mechanism of Asian dust particles through both laboratory-scale experiment and model calculation. To artificially simulate Asian dust particle, $CaCO_3$ particles were generated inside an experimental chamber. They were then scavenged by the artificial rain drops. The abundant $CaCO_3$ particles scavenged on a rain drop were successively identified by SEM observation. The concentrations of Ca in residual $CaCO_3$ particles on individual droplet were quantified by PIXE analysis. There was a tendency toward a high accumulation of Ca on a relatively small drop (e.g., <1.0 mm diameter). It is thus suggested that smaller rain drops can effectively scavenge a significant amount of Asian dust particles in ambient atmosphere. The numerical estimation can account for 92.1% and 83.2% of Ca that were measured in small (<1.0 mm diameter) and large (>2.0 mm diameter) size drops, respectively.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.128-137
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• 1998

In this numerical experiment, the preconditioned compressible Navier-Stokes equation is tested to analyze the laminar spray combustion. Sprayed flow field is formulated by Eulerian-Lagrangian system for the gas and liquid phases each. DSF(Deterministic Separated Flow) model was adopted for the sprays with the vortex model to describe transients of individual droplet heating. Simplified single global reaction model approximates methanol-air reaction with and without disk flame holder. The equation system is discretized by finite difference technique and time integrated by LU-SGS. Due to greatly simplified chemical reaction mechanism and the lack of experimental evidences, most of the efforts were devoted to show the applicability and robustness of preconditioned compressible flow calculation algorithm. Computation results in qualitatively reasonable combusting flow field, hence it is believed that further refinement are required to produce quantitatively accurate solutions.

• 센서학회지
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• 제18권2호
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• pp.154-159
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• 2009

This paper describes two methods - stamp-to-stick bonding and microtransfer molding - to integrate microfluidic channel into an optoelectrofluidic device for in-channel microparticle manipulation. We have demonstrated the optoelectronic microparticle manipulation in the channel-integrated optoelectrofluidic device using a liquid crystal display. As injecting a liquid sample containing $15{\mu}m$-diameter polystyrene particles into the fabricated channel, trapping and transport of individual microparticles have been successfully demonstrated. This channel-integrated optoelectrofluidic device may be useful for several in-channel applications based on the optoelectrofluidics such as optoelectronic flow control, droplet-based protein assay and bead-based immunoassay.

• 한국항공우주학회지
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• 제44권4호
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• pp.290-297
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• 2016

사각덕트에서 난류 유동장으로 분사되는 액체 제트의 액주 분열과 미립화 현상에 관한 LES를 수행하였다. 기체상태의 공기 유동 해석에 오일러리안 해법을 사용하고, 액적 추적을 위하여 라그랑지안 해법을 사용하여 기체-액체간 이상유동(two phase flow) 해석을 수행하였다. 액적 분열 모델, 아격자 스케일 모델 및 공간 차분법에 따른 액적 분열을 조사하였다. 액체 제트의 침투깊이를 경험식과 비교하였으며 경험식보다 약간 높음을 알 수 있었다. 제트 후류에서 사우터 평균직경에 대한 분석을 수행하였다.

• 한국작물학회지
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• 제42권6호
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• pp.821-832
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• 1997

본 실험은 알파파 꽃 추출물로부터 Allelopathy와 Autotoxicity에 관련되는 활성물질을 분리, 동정하기 위하여 실시하였다. 알팔파 꽃 200g을 80% MeOH로 추출하여 $CHCl_3$층을 silica gel thin layer chromatography (TLC), microcrystalline cellulose thin layer chromatography (MCTLC)와 droplet countercurrent chromatography(DCCC)의 분획을 이용하여 생물검정을 행하고 DCCC의 생물검정에서 가장 억제력을 보였던 분획 5와 6은 HPLC로 활성물질을 동정하였다. HPLC분석 결과 분획 5에서는 ferulic acid, caffeic acid, vanillic acid, rutin, narringin 이, 분획 6에서는 ferulic acid, caffeic acid, vanillic acid, rutin, coumarin이 동정되었다. 이들 동정된 물질을 이용한 알팔파와 돌피에 대한 발아실험에서도 모두 알팔파와 돌피의 발아와 생육에 억제적으로 작용하였으며, 이중 coumarin의 처리가 가장 억제적이었다. 따라서 이들 물질이 알팔파와 돌피의 autotoxicity와 allelopathy에 관련하는 것으로 생각되었다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제24권3호
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• pp.49-57
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• 2018

Purpose: The increase in patients requiring hemodialysis has resulted in an increase dialysis-associated infections risk. but there are no Renal Dialysis unit design standard meet specified safety and quality standards. Therefore, appropriate Establish standards and legal regulation is important for the provision of initial certification and maintenance of facility, equipment, and human resource quality. Methods: Literature survey on the design guideline and standards of Renal Dialysis unit design in Korea, U.S, Germany, Singapore, Hongkong, Dubai. Results: There are no established standards for facilities in dialysis units in Korea. To prevent infections in dialysis patients, necessary establish standards. Considering the domestic and overseas Health-care facilities standards, the major factors to be considered in the medical environment for Renal Dialysis Unit are as follows. First, planning to separate Clean areas(treatment area) from contaminated areas(medical waste storage area). Second, ensure sufficient space and minimum separation distance. Although there may be differences depending on the circumstances of individual institutions, renal dialysis unit consider the space to prevent droplet transmission. Third, secure infrastructure of infection prevention such as sufficient amount of hand hygiene sinks. Hand washing facilities for staff within the Unit should be readily available. Hand hygiene sinks should be located to prevent water from splashing into the treatment area. Fourth, Heating, ventilation and air conditioning (HVAC) system for Renal Dialysis Unit is all about providing a safer environment for patients and staff. Implications: The results of this paper can be the basic data for the design of the Renal Dialysis Units and relevant regulations.

• 한국입자에어로졸학회지
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• 제9권1호
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• pp.7-21
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• 2013

Twelve-hour size-resolved atmospheric aerosols were measured to determine size distributions of water-soluble organic carbon(WSOC) during daytime and nighttime, and to investigate sources and formation pathways of WSOC in individual particle size classes. Mass, WSOC, ${NO_3}^-$, $K^+$, and $Cl^-$ at day and night showed mostly bimodal size distributions, peaking at the size range of $0.32-0.55{\mu}m$(condensation mode) and $3.1-6.2{\mu}m$(coarse mode), respectively, with a predominant condensation mode and a minor coarse mode. While ${NH_4}^+$ and ${SO_4}^{2-}$ showed unimodal size distributions which peaked between 0.32 and $0.55{\mu}m$. WSOC was enriched into nuclei mode particles(< $0.1{\mu}m$) based on the WSOC-to-mass and WSOC-to-water soluble species ratios. The sources and formation mechanisms of WSOC were inferred in reference to the size distribution characteristics of inorganic species(${SO_4}^{2-}$, ${NO_3}^-$, $K^+$, $Ca^{2+}$, $Na^+$, and $Cl^-$) and carbon monoxide. Nuclei mode WSOC was likely associated with primary combustion sources during daytime and nighttime. Among significant sources contributing to the condensation mode WSOC were homogeneous gas-phase oxidation of VOCs, primary combustion emissions, and fresh(or slightly aged) biomass burning aerosols. The droplet mode WSOC could be attributed to aqueous oxidation of VOCs in clouds, cloud-processed biomass burning aerosols, and small contributions from primary combustion sources. From the correlations between WSOC and soil-related particles, and between WSOC and sea-salt particles, it is suggested that the coarse mode WSOC during daytime is likely to condense on the soil-related particles($K^+$ and $Ca^{2+}$), while the WSOC in the coarse fraction during nighttime is likely associated with the sea-salt particles($Na^+$).