• Korean Chemical Engineering Research
• /
• v.55 no.1
• /
• pp.68-73
• /
• 2017

The removal of particulate matter ranging from $0.01{\mu}m{\sim}10{\mu}m$ can be performed by using membrane filters composed of fibers. Electrospinning techniques offer the production of very thin fibers with a uniform fiber diameter over conventional techniques including template synthesis, melt-blown, phase separation, etc. Air filtration will be improved with electrospun membranes due to the open pore structures, high porosity, and large surface area of the membranes. In the present study, filtration efficiency increased with pore size decrease and fiber density increase induced by carbon nanotube and the increased CA (cellulose acetate) concentration during electrospinning process.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.29.2-29.2
• /
• 2009

21세기 제 3의 산업혁명을 가져올 것으로 기대되는 나노기술(NT), 정보기술(IT), 바이오기술(BT)은 전 세계 과학자들의 마음을 사로잡고 있다. 이 가운데 나노기술은 전자산업에 응용 시 그 기대효과는 우리가 상상하는 이상의 것이라 예상하고 있다. 나노기술에 특히 관심을 가지는 이유는 물질이 마이크로미터 크기로 작아져도 벌크물질의 물리적 특성이 그대로 유지되지만, 나노미터 크기가 되면서 우리가 경험하지 못했던 새로운 물리적 특성들이 발현되기 때문이다. 그 특성에는 양자구속효과, Hall-Petch 효과, 자기효과 등이 있다. 나노기술의 구현은 양자점과 같은 영차원 나노입자, 나노와이어, 나노막대, 나노리본 등과 같은 직경이 100nm 이하의 일차원 구조의 나노물질 및 나노박막과 기타 100nm 이하의 나노구조물들이 사용된다. 현재 일차원 구조를 이용한 전자디바이스화 연구는 결정성장을 정확하게 조절하는 합성기술, 합성된 일차원 나노물질의 물리적 특성을 지배하는 각종 파라미터들과 물리적 특성들과의 상관관계 정립, 나노와이어를 이용한 Bottom-up 방식에 의한 조립기술 확보를 위해 활발히 진행 중이다. 하지만 나노구조의 특성을 확인하는 형태의 연구일 뿐, 실제 디바이스 구현에는 여전히 많은 과제를 안고 있다. 본 연구에서는 선택적 삼원계 단결정 씨앗층을 이용한 길이/직경 비가 매우 향상된 MgZnO 나노와이어를 interfacial layer 없이 수직으로 성장하여 산화물 전계방출 에미터로서의 가능성을 확인하였다.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1393-1406
• /
• 2018

In this study, three parameters (Pressure ($X_1$), Airflow rate ($X_2$), Operation time ($X_3$)) were experimentally designed and the predicted model and optimal conditions were established by using the terminal rise velocity of the microbubbles as the response value. The polynomial regression analysis showed that the optimum value for the terminal rise velocity at the Pressure ($X_1$) of 4.5 bar, Airflow rate ($X_2$) of 3.3 L/min and Operation time ($X_3$) of 2.2 min was 5.14 cm/min ($85.7{\mu}m/sec$). Also, the highest microbubble diameter size distribution in the range of 2 to $5{\mu}m$ and 25 to $50{\mu}m$ was confirmed by using a laser particle counting apparatus.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.4
• /
• pp.532-538
• /
• 2014

Arsenic (As) is nonessential element toxic to plants. In Korea little is not only known about the extent of actual anthropogenic sources and inputs of arsenic to the agricultural land which plays a active role as a sink, but also systematic research on arsenic as an toxic element entering the food chain via the soil-plant pathway has not been investigated in the fields and greenhouses besides in few places of abandoned mining sites. Therefore, it is important to focus on the effect of As-contaminated soils on As uptake and biomass production of lettuce plants. In this study, As concentrations in the soil and accumulation of As in lettuce transferred by As uptake from soils were investigated. To do this, soil which was mixed with various rates of arsenopyrite gravels containing arsenic from 0 to 100% was packed into a round plastic pot. Then, 10 days old vegetable crops of chinese cabbage and lettuce after germination were transplanted into a pot. Growth of lettuce was observed for four weeks with one week interval. All experiments were done by triplicate. The results showed that the growth rates for number of leaves, width and length of the crop plants were retarded with increasing amount of gravel mixed due to increasing bioavailable amount of arsenate with increasing rate of gravel in soils. With these results, we conclude that the bioavailable amount of arsenate can influence the growth of lettuce.

• Clean Technology
• /
• v.27 no.1
• /
• pp.39-46
• /
• 2021

A road structure washing vehicle equipped with a 4 HP, 80 LPM ultrafine bubble generator was used to clean a tunnel wall and the surface of the surrounding structure, consisting of concrete and tiles, in a heavy traffic area around an apartment complex in the city. Ultrafine bubbles were generated by supplying air at 2 to 3 LPM and using a specially designed nozzle, whereas fine bubbles made by an impeller in a gas-liquid mixing self-priming pump were produced with an average diameter of 165.4 nm and 6.81 × 107 particles mL-1. Using a high pressure washer gun that can perform high-pressure cleaning at 150 bar and 30 LPM, ultrafine bubbles were used to wash dust adsorbed on the surface of the road structures. The experimental analysis was divided into before and after washing. The samples were analyzed by applying ISO 8502-3 to measure surface contamination of dust adsorbed on the surface. Using the transparent tape attached to the surface, the removal rate was calculated by measuring the weight of the dust, and the number of particles was calculated using the gravimetric method and the software, ImageJ. The results of the experiment showed that the number of dust particles adsorbed on the tile wall surface before and after washing were 3,063 ± 218 particles mL-1 and 20 ± 5 particles mL-1, respectively, with weights of 580 ± 82 mg and 13 ± 4 mg. Particles on the surface of the concrete structure before and after washing were 8,105 ± 1,738 particles mL-1 and 39 ± 6 particles mL-1, respectively, with weights of 1,448 ± 190 mg and 118 ± 32 mg.

• Journal of Plant Biotechnology
• /
• v.49 no.2
• /
• pp.145-149
• /
• 2022

Airborne fine dust (FD) particles smaller than 10 ㎛ in diameter (PM10) are one of the major causes of air pollution in East Asia, including Korea, and have become a major contributor to respiratory and skin problems. FD inordinately promotes the production of reactive oxygen species and inflammatory response in macrophages, leading to cell damage and death. Rosa rugosa, a deciduous shrub of the Rosa genus, has been used in traditional East Asian herbal medicine to treat various illnesses. The present study investigated the anti-inflammatory effects of R. rugosa organ extracts on PM10-stimulated RAW264.7 macrophages. Compared to non-treated RAW264.7 cells, treatment with 100 ㎍.ml^-1 PM10 resulted in increased nitric oxide (NO) production, similar to lipopolysaccharide treatment. Additionally, 100 ㎍/ml stem extract reduced NO production by more than 45% compared to mock treatment. Furthermore, PM10-induced expression of interleukin (IL)-1β, IL-6, inducible NO synthase, and cyclooxygenase-2 was significantly reduced by stem extract treatment, indicating that the anti-inflammatory effect of the stem extract is mediated by the inhibition of pro-inflammatory mediators in PM10-stimulated RAW 264.7 cells. These results indicate that the R. rugosa stem could be considered a natural remedy with a protective effect against inflammatory responses induced by harmful airborne dust.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.454-462
• /
• 2023

Flash lamp annealing (FLA) of metal nanoparticle (NP) ink has provided powerful strategies to fabricate high-performance electrodes on a flexible substrate because of its rapid processing capability (in milliseconds), low-temperature process, and compatibility with to roll-to-roll process. However, metal NPs [e.g., gold (Au), silver (Ag), copper (Cu), etc.] have limitations such as difficulty in synthesizing fine metal NPs (diameter less than 10 nm), high price, and degradation during ink storage and FLA processing. In this regard, organometallic ink has been proposed as a material that can replace metal NPs due to their low-cost (usually 1/100 times cheaper than metal nano inks), low-temperature processability, and high material stability. Despite these advantages, the fabrication of flexible electrodes through FLA treatment of organometallic compounds has not been extensively researched. In this paper, we experimentally guide how to determine the optimal conditions for forming electrodes on flexible substrates by considering material parameters, and flashlight processing parameters (energy density, pulse duration, etc) to minimize the difficulties that may arise during the FLA of organometallic ink.

• Food Science and Preservation
• /
• v.30 no.4
• /
• pp.630-641
• /
• 2023

The quality characteristics of muffins with different types of rice flour, such as soft flour (CON), soft rice flour (SRF), floury rice flour (FRF), and rice flour (RF) were assessed by using Image J program, which includes their particle size analysis, moisture content, pH, color, specific volume, baking loss rate, texture. (D[4, 3]) is weighted mean diameter, which is directly obtained in particle size measurements showed large values in the order of rice flour, floury rice flour, soft rice flour, and soft flour. The moisture content was high in the CON and SRF groups with small particle sizes. There was no significant difference in pH, L and b value. The a value was significantly low only in the RF group with large particle size. The smaller the particle size, the higher the specific volume and baking loss rate. Image J showed that the number of pores decreased when fewer smaller particles were the powder, but the pores were larger. Among the rice flours, the SRF group, excluding the CON group, scored high in all the acceptability elements. The results from this study can be used as basic data that can contribute to research on various rice-processed foods.

• Journal of Adhesion and Interface
• /
• v.11 no.4
• /
• pp.144-148
• /
• 2010

It reports the surface modification of gold nanoparticles (AuNPs) by the synthesis of thin silica layer and the fabrication of AuNPs monolayer on the glass surface. AuNPs of 10 nm in diameter were prepared in aqueous solution. A silica layer was synthesized at the different concentration of tetraethlyorthosilicate for the control of silica layer thickness. Langmuir-Blodgett (LB) film was fabricated by dispersing AuNPs on the aqueous solution and raising a surface pressure up to a solid phase. The change of AuNPs' size was observed by the change of UV/Visible spectra. Atomic force microscopic images confirmed the reliable fabrication of AuNPs LB films.

• Journal of Energy Engineering
• /
• v.11 no.2
• /
• pp.166-177
• /
• 2002

The present study is described of the flame structure of one-dimensional, flat, premixed, laminar, coal-air flame with some addition of methane for the flame stability. A low pressure burner operating at a combustion pressure of 0.3 arm was employed in order to extend the reaction zone. Predicted results from the models considered in the present study are compared with experimental results. Comparisons are included gas temperatures, species concentrations, char analysis and measured burning velocity. Among the models, Model II $I^{*}$-d, which specified devolatilization rate constants and a char surface area factor S=4, resulted in good agreement within the present experimental ranges. The results of char analysis suggest that the extent of the reaction occurring on the panicle might be underestimated in the model so that the char surface area should be increased. A value of 4 for this factor was given by sensitivity analysis of change in char surface area. Again, model II $I^{*}$-d gave satisfactory predictions of burning velocities over most of the experimental range studied. It has been clearly shown that the particle diameter appreciably affects the rates of devolatilisation and char oxidation through the effects of thermal lag and volumetric reactive surface area, consequently laminar burning velocity.ity.