• 한국분무공학회지
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• 제6권2호
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• pp.16-21
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• 2001

This paper describes the macroscopic behavior and atomization characteristics of the high-pressure gasoline swirl injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. The atomization characteristics of gasoline spray such as mean diameter and mean velocity of droplets were measured by the phase Doppler particle analyzer system. The macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 7 and 10 MPa of injection pressure under different spray cone angle. The results of this work show that the geometry of injector was more dominant over the macroscopic characteristics of spray than the fuel injection pressure and injection duration. As for the atomization characteristics, the increase of injection pressure resulted in the decrease of fuel droplet diameter and the atomization characteristics differed as to the spray cone angle. The most droplets had under $25{\mu}m$ diameter and for the large droplets(upper $40{\mu}m$) as the spray grew the atomization presses were very slow. Comparison results between the measured droplet distribution and the droplet distribution functions revealed that the measured droplet distribution is very closed to the Normal distribution function and Nukiyama-Tanasawa's function.

• 한국분말재료학회지
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• 제13권2호
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• pp.138-143
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• 2006

In this study, the effects of the dispersants, i.e., Hypermer KD-2 and poly(l-vinyl-2-pyrrolidone) (PVP), and their concentration on the dispersion stability of Ni nanoparticles ($10nm{\sim}40nm$) in ethanol were investigated by using a visual inspection, a transmission profile (Turbiscan), and a zeta potential measurement. The transmission profiles measured by Turbiscan showed that the particle size increased over the entire height of the sample for suspensions with both the dispersants without showing any particle coalescence and sedimentation. The visual inspection also confirmed that the Ni suspensions with Hypermer KD-2 and PVP were very stable for more than a year. The zeta potential values varied from positive to negative with increasing the dispersant's concentration. The dispersion stability of the suspensions was not affected by both the dispersant's concentration and the zeta potential values. The observed suspension stability of Ni nanoparticles was attributed to the steric effect for the Hypermer KD-2 and to the bridging effect for the PVP.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.39-42
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• 2006

Titania sols or powders were are very promising materials for environment as photocatalyst. The band gap energy of $TiO_2$ has been known to be 2.8 to 3.2 eV. But the measuring system of its band gap is usually depend on absorption properties. Thus, in this study, absorption properties of $TiO_2$ sols prepared by hydrothermal process were researched with the effect of various particle sizes and concentrations. The mean particle size in $TiO_2$ sols increased as 15 nm to 60 nm, absorption graph measured by UV-Vis spectrometer shows to move red-shift. When dilute solution added with $2^n$ in $TiO_2$, the band gap energy increases as linear function.

• 한국응용과학기술학회지
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• 제19권2호
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• pp.131-136
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• 2002

As model waterborne acrylic coatings, mono-dispersed poly(butyl acrylate-methyl methacrylate) copolymer latexes of random copolymer and core/shell type graft copolymer were prepared by seeded multi-staged emulsion polymerization with particle size of $180{\sim}200$ nm using semi-batch type process. Sodium lauryl sulfate and potassium persulfate were used as an emulsifier and an initiator, respectively. The effect of particle texture including core/shell phase ratio, glass transition temperature and crosslinking density, and film forming temperature on the film formation and final properties of film was investigated using SEM, AFM, and UV in this study. The film formation behavior of model latex was traced simultaneously by the weight loss measurement and by the change of tensile properties and UV transmittance during the entire course of film formation. It was found that the increased glass transition temperature and higher crosslinking degree of latex resulted in the delay of the onset of coalescence of particles by interdiffusion during film forming process. This can be explained qualitatively in terms of diffusion rate of polymer chains. However, the change of weight loss during film formation was insensitive to discern each film forming stages-I, II and III.

• 에너지공학
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• 제13권1호
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• pp.75-81
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• 2004

본 연구에서는 ZZF탈황제의 내마모성을 개선하기 위하여 산화칼슘함량을 1, 3, 5, wt%정도 첨가한 탈황제를 제조하여 마모실험을 수행하였다. 마모실험전과 후의 탈황제 형상을 SEM으로 관찰하고 입자크기분포를 쿨터계수기로 측정하였다. 산화칼슘을 첨가하지 않은 ZZF 탈황제의 마모도는 Al=28.3%, CAI=10.8% 정도였다. CaO 함량이 3 wt%인 ZZFCa-3 탈황제의 마모도(Al=17.3%, CAI=8.8%가 가장 낮았다. ZZFCa 3 탈황제가 입자모양과 평균입도가 잘 유지되었다 ZZFCa-3 탈황제의 황화 및 재생실험을 수행하였다. 석탄가스 중의 10000 ppm수준의 H$_2$S를 1 ppm 이하로 정제할 수 있었으며, 탈황제의 황수용능력은 최대 28.8 g S/100 g sorbent정도 유지되었다. 재생된 탈황제의 XRD분석에서 CaSO$_4$실 생성은 관찰되지 않았으며, 황화반응에서도 SO$_2$ slippage가 관찰되지 않았다. 이러한 결과로 국내 고유 기술에 의한 반응성, 내구성, 내마모성이 모두 만족되는 고온건식 탈황제를 개발할 수 있었다.

• Preventive Nutrition and Food Science
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• 제17권3호
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• pp.197-202
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• 2012

Normal (cv. Keumkang, KK) and waxy-type (cv. Shinmichal, SMC) whole wheat flour was substituted at 20 and 40% for white wheat flour (WF) during bread dough formulation. The flour blends were subjected to dough and baking property measurement in terms of particle size distribution, dough mixing, bread loaf volume and crumb firmness. The particle size of white wheat flour was the finest, with increasing coarseness as the level of whole wheat flour increased. Substitution of whole wheat flour decreased pasting viscosity, showing all RVA parameters were the lowest in SMC40 composite flour. Water absorption was slightly higher with 40% whole wheat flour regardless of whether the wheat was normal or waxy. An increased mixing time was observed when higher levels of KK flour were substituted, but the opposite reaction occurred when SMC flour was substituted at the same levels. Bread loaf volume was lower in breads containing a whole wheat flour substitution compared to bread containing only white wheat flour. No significant difference in bread loaf volume was observed between normal and waxy whole flour, but the bread crumb firmness was significantly lower in breads containing waxy flour. The results of these studies indicate that up to 40% whole wheat flour substitution could be considered a practical option with respect to functional qualities. Also, replacing waxy whole flour has a positive effect on bread formulation over normal whole wheat flour in terms of improving softness and glutinous texture.

• 대한기계학회논문집B
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• 제36권7호
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• pp.737-744
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• 2012

차량에 의한 대기오염을 실제 주행 조건에서 시간과 공간에 구애받지 않고 실시간으로 측정하기 위하여 이동형 배출가스 측정장치(MEL)가 제작되었다. 미니밴 차량에 CO, NOx, $CO_2$와 같은 배출가스 측정 장비와 입자의 수농도 및 입경별 개수농도 분포 측정을 위한 FMPS, CPC가 탑재되었다. 차량 전단에 장착되는 흡입 샘플링 포트를 사용하여 여러 종류의 차량 추적 실험을 수행하였다. 본 연구에서는 MEL의 상세 사양 및 이를 이용하여 디젤 및 가솔린 연료를 사용하는 승용차량들을 추적 실험한 결과를 나타내었다. 디젤 차량에서 배출되는 입자의 수농도는 가솔린 차량에서 배출되는 입자의 수농도보다 높았으며 다량의 극미세입자를 포함하고 있었다. 하지만, 직접분사식 가솔린 차량은 DPF가 장착된 디젤 차량에 비하여 50 nm 이상의 입경 영역에서 입자의 농도가 높은 경향을 보였다.

• 한국건축시공학회지
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• 제8권4호
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• pp.105-114
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• 2008

This study investigates the saturation level of surface dryness, quantity of adhesive mortar, and the alien substance content of recycled aggregates for concrete to develop an adequate quality testing method for understanding the properties of recycled aggregates, which differ greatly from preexisting aggregates. For tests that measure the saturation level of surface dryness, where detail methods are applied differently according to the tester, various testing methods from across world were compared and analyzed. This study revealed that when measuring the saturation level of surface dryness of a certain sample, aggregates must be supplemented immediately whenever the height of the sample becomes lower than the measuring mold, and allowing the tamper to free fall on the sample will provide the most accurate results. When measuring the quantity of adhesive mortar of recycled aggregates for concrete, an acid solution was used, and since the quantity of adhesive mortar increases as the particle sizes gets smaller, the sample for testing should represent the entire granularity. Sulfuric acid solution is adequate for immersion, and the concentration should be 20% for best results. According to the alien substance content measurement, which was examined by the naked eye, the error range caused by the difference in particle size was neglectable, and therefore the sample should be $2.5{\sim}5.0mm$ in size concerning the accuracy and measuring time. Also, for coarse recycled aggregates, the sample should amount to 1kg for measuring alien substance content by the naked eye, which proves that assortment by the naked eye is the most adequate method for measuring the alien substance content of a recycled aggregate.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.365-370
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• 2014

For real-time monitoring of colloidal nanoparticles (NPs) in aqueous media, a light sheet type dark-field microscopy system combined with a microfluidic concentration gradient generator (${\mu}FCGG$-LSDFM) was developed. Various concentrations of colloidal Au NPs were simultaneously generated with the iFCGG and characterized with the LSDFM setup. The number concentrations and hydrodynamic size distributions were measured via particle counting and tracking analysis (PCA and PTA, respectively) approaches. For the 30 nm Au NPs used in this study, the lower detection limit of the LSDFM setup was 3.6 ng/mL, which is about 400 times better than that of optical density measurements under the same ${\mu}FCGG$ system. Additionally, the hydrodynamic diameter distribution of Au NPs was estimated as $39.7{\pm}12.2nm$ with the PTA approach, which agrees well with DLS measurement as well as the manufacturer's specification. We propose this ${\mu}FCGG$-LSDFM setup with features of automatic generation of NP concentration gradient and real-time monitoring of their physicochemical characteristics (e.g., number concentration, and hydrodynamic size distribution) as an important component of future high-throughput screening or high-content analysis platforms of nanotoxicity.

• 대한화장품학회지
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• 제30권2호
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• pp.207-210
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• 2004

유용성 감초산은 강한 항염 작용으로 주름개선용 기능성 화장품에서 널리 사용되어지는 물질이다. 그러나 용해성이 좋지 않고 빛, 열, 산소에 의하여 변질되기 쉽다. 본 연구에서는 유용성감초산을 PG/hydrogenated lecithin/MCT/glycerine/water를 microfluidzer를 이용해 30-50nm인 nanosolve-licorice를 만들고, 잘 용해된 nanosolve-licorice를 다공성 PMMA에 에탄올과 함께 넣은 후 microfluidzer를 1000 BAR에서 연속 3회 처리하여 안정화시켰다. 이 실험에서 글라블리딘 함량을 HPLC로 측정한 결과 기존의 리포좀에 비하여 3-5배 정도 안정성을 보였으며, PMMA 캡슐로 된 리코러스는 피부의 침투가 기존 리포솜에 비하여 월등히 우수하여 항염 효과를 더욱 증가시켰다. 이러한 실험을 image analyzer, particle size analyzer, FF-TEM, chromameter, HPLC등의 분석장비를 사용하였다.