• 한국입자에어로졸학회지
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• 제12권3호
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• pp.65-72
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• 2016

Nanoporous $SiO_2$ particles containing different pore volume and size were prepared from silicic acid by a spray pyrolysis. The pore size, pore volume and particle size could be controlled with varying the precursor concentration, reaction temperature, and amount of organic templates such as Urea and poly ethylene glycol (PEG). The pore size distribution, pore volume and specific surface area of as-prepared particles were analyzed by BET and BJH methods, and the average particle sizes were measured by a laser diffraction method. The nanoporous $SiO_2$ particles ranged $0.6-0.9{\mu}m$ in diameter were successfully synthesized and the average particle size increased as the silicic acid concentration increased. The morphology of nanoporous $SiO_2$ particles was spherical and pores ranged 1 - 40 nm in diameter were measured in the particles. In case of Urea added into silicic acid, it showed no much difference in the morphology, pore size and pore volume at different Urea concentration. On the other hand, when PEG was added, it was clearly observed that pore diameter and pore volume of the particles surface increased with respect to PEG concentration.

• 한국화재소방학회논문지
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• 제30권6호
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• pp.111-117
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• 2016

본 연구는 스프링클러 헤드 근처에서 형성되는 액막의 자유표면 유동에 대해 CFD 모델을 적용하여 해석하고 스프링클러의 초기분무 특성 예측을 위한 기존 이론식의 결과와 비교를 통해 이론 모델의 타당성을 검토하였다. CFD 해석은 상용 해석프로그램인 CFX 14.0을 이용하였으며 노즐과 디플렉터로 이루어진 단순형상에 대해 표준난류모델과 VOF법을 적용하여 해석을 수행하였다. 평판부의 디플렉터 끝단에서 속도분포는 CFD 해석과 경험식이 매우 잘 일치된 결과를 보였으나 기하학적 형상이 복잡한 부분에서는 속도분포의 차이를 보였다. 이론모델에서 예측된 평균액적크기는 실제 스프링클러 헤드에서 측정된 평균액적크기에 대한 이전 연구결과와 큰 차이를 보였다. 그러나 이론 모델은 스프링클러 헤드의 초기 액적형성과정의 메커니즘을 이해하고 실험적 접근이 용이하지 않은 상황에서 분무 액적의 특성을 예측하는데 유동한 도구로 활용될 수 있다.

• 한국분무공학회지
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• 제24권3호
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• pp.114-121
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• 2019

The effect of injector driving current pattern on fuel injection rate of solenoid diesel common rail injector was studied by computer simulation. The time resolved fuel injection rate and injected quantity per stroke of a common rail injector driven with the five current patterns were computer simulated. The fuel injection rate and injected quantity per stroke according to the rail pressure and fuel injection period were also computer simulated. When the common rail injector was driven with the five driving current patterns of peak & hold, there was no difference in the fuel injection rate in the peak section regardless of all the current patterns of the five cases. On the other hand, the magnitude of the hold current value influenced the injection rate and injected quantity per stroke. That is, in the current pattern of three cases where the hold current value is equal to or more than a constant value of the peak current value, the fuel injection rates for the given common rail rail pressure and injection period are same one another. On the other hand, the current pattern of the two cases, in which the hold current value is smaller than a certain value, there is a large fluctuation in the fuel injection rate.

• 한국도로학회논문집
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• 제16권5호
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• pp.49-58
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• 2014

PURPOSES : In areas of high traffic volume, such as expressway across large cities, the amount of nitrogen oxides (NOx) emitted into the atmosphere as air pollution can be significant since NOx gases are the major cause of smog and acid rain. Recently, the importance of NOx removal has arisen in the world. Titanium dioxide ($TiO_2$), that is one of photocatalytic reaction material, is very efficient for removing NOx. The NOx removing mechanism of $TiO_2$ is the reaction of solar photocatalysis. Therefore, $TiO_2$ in road structure concrete need to be contacted with ultraviolet rays (UV) to be activated. In general, $TiO_2$ concretes are produced by replacement of $TiO_2$ as a part of concrete binder. However, considerable portion of $TiO_2$ in concrete cannot contact with the pollutant in the air and UV. Therefore, $TiO_2$ penetration method using the surface penetration agents is attempted as an alternative in order to locate $TiO_2$ to the surface of concrete structure. METHODS : This study aimed to evaluate the NOx removal efficiency of photocatalytic concrete due to various $TiO_2$ application method such as mix with $TiO_2$, surface spray($TiO_2$ penetration method) on hardened concrete and fresh concrete using surface penetration agents. The NOx removal efficiency of $TiO_2$ concrete was confirmed by NOx Analyzing System based on the specification of ISO 22197-1. RESULTS : The NOx removal efficiency of mix with $TiO_2$ increased from 11 to 25% with increasing of replacement ratio from 3 to 7%. In case of surface spray on hardened concrete, the NOx removal efficiency was about 50% due to application amount of $TiO_2$ with surface penetration agents as 300, 500 and 700g/m2. The NOx removal efficiency of surface spray on fresh concrete due to all experimental conditions, on the other hand, which was very low within 10%. CONCLUSIONS : It was known that the $TiO_2$ penetration method as surface spray on hardened concrete was a good alternative in order to remove the NOx gases for concrete road structures.

• 한국응용곤충학회지
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• 제19권4호
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• pp.212-220
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• 1980

이 시험은 도입남양재 원목에 부착 또는 서식하는 유해병해충의 방제를 목적으로 실시하는 해수수침소독에 있어 농약의 소요량기준을 설정함을 목표로 실시한 것으로써 결과를 요약하면 다음과 같다. 1. 우리나라에 도입되는 남양재 원목의 평균 길이는 11.12m이었으며 직경은 69.55cm이었다. 2. 원목의 전재적에 대한 부상재적은 평균 $20.82\%$ 이었다. 3. 원목의 전재적에 대한 부상표면적의 비의 값은 2.3356($95\%$ 신뢰수준)이었다. 4. 원목의 전재종 대 부상표면적에 대한 표본추출오차는 1본선내 원목간의 오차(0.2087)가 10본선간의 오차(0.2952)보다 적었다. 5. 원목 $1m^2$당 농약의 적정소요량은 수동식살포기를 이용하는 경우 0.368cc, 그리고 동력분무기를 이용하는 경우는 0.295cc이었다. 6. 예를 들어 남양재 원목 $5,000m^3$을 도입하여 동력분무기로 해수수침소독을 실시하는 경우 농약소요량은 다음과 같이 계산된다. $$5,000\;M^3\times2.333=11,678\;M^2$$ $$11,678M^2\times0.295=3,445cc$$.

• 한국화재소방학회논문지
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• 제33권5호
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• pp.28-36
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• 2019

본 연구에서는 분사 형태(Spray pattern)가 중실원추형(Full cone) 및 중공원추형(Hollow cone)인 2유체 미립화기를 이용하여 공급 기체 및 미분무가 헵탄 풀화재(Heptane pool fire) 소화 성능에 미치는 영향을 검토하였다. 2유체 미립화기의 공급 기체로 30 lpm (Liter per minute; L/min)의 공기 또는 질소를 이용하였으며, 물을 공급하지 않은 경우(즉, 공기 또는 질소만 분사한 경우)와 물 0.085 lpm을 공급한 경우(즉, 미분무와 공급 기체를 함께 분사한 경우)에 대해 실험을 수행하였다. 실험 결과, 공급 기체만 분사한 경우보다 미분무와 공급 기체를 함께 분사한 경우에, 그리고 중공원추형인 경우보다 중실원추형인 경우에 빠르게 화재 소화 가능함을 확인하였다. 또한, 중실원추형의 경우, 미분무와 공급 기체 함께 분사 시 화재 소화 성능에 미분무의 영향은 지배적이었으나 공급 기체의 영향은 미비한 것으로 관찰되었다. 반면, 중공원추형의 경우, 중실원추형과 달리 미분무와 공급 기체 함께 분사 시 공급 기체로 질소를 공급한 경우가 공기를 공급한 경우에 비해 평균 화재 소화 시간이 확연하게 짧아지는 것으로 측정되었고, 이를 통해 미분무 뿐 아니라 공급 기체도 화재 소화 성능에 지대한 영향을 미칠 수 있음을 확인하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.124.2-124.2
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• 2016

Corrosion resistance and adhesion of electro-paint (E-paint) with fluoride conversion coating (FCC) on AZ31 Mg alloy were studied. Corrosion resistance and adhesion were studied as a function of FCC-treatment time and concentration of FCC-bath. Aqueous hydrogen fluoride (HF) solutions, with concentrations ranging from 0.5 M to 5 M, were used to form FCC on chemically polished AZ31 Mg alloy samples for six different times; 10, 30, 60, 90, 120, and 180s. The results from salt spray test (SST) showed that corrosion resistance of E-paint appeared to decrease with increasing FCC treatment times in low concentration FCC baths. The number of blisters formed on the FCC-treated samples increased with increasing FCC treatment time of more than 1 min in low concentration (0.5 M to 1 M) solutions. On the other hand, samples treated in the 5 M HF solution for 120s showed no delamination or blistering even after 1200h of SST.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.9-17
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• 2001

This paper is the second of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected Sl engine by visualizing for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been captured through the quartz window in the piston head with an ICCD camera. Fuel has been replaced with an air-ethanol mixture to utilize atomized fuel spray fur the visualization purposes. This results have been compared with steady flow concentration measurement. For low/medium swirl port, the early injection makes such a fuel distribution state that is upper-rich, middle-lean and lower-rich along the combustion chamber and cylinder by tumbling motion. On the other hand, the late injection induces upper-rich, middle-lean and lower-rich state due to the short fuel penetration.

• 한국분무공학회지
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• 제12권2호
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• pp.108-114
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• 2007

This study investigates the influence of energizing duration on the fuel atomization characteristics of biodiesel injected through a high pressure common-rail injector. In order to analyze the effect of energizing duration on the fuel injection rate performance, the injection rate of biodiesel fuel is obtained from the pressure variation in the tube filled with fuel in injection measuring system. On the other hand, the atomization characteristics of biodiesel was measured and compared in terms of Sauter mean diameter(SMD), arithmetic mean diameter(AMD), droplet mean velocity, and detected droplets number by applying a phase Doppler particle analyzer(PDPA). It was revealed that the injection mass and maximum injection rate increase with increase of the energizing duration. Moreover, the increase of energizing duration improves the atomization performance of biodiesel fuel because it induces higher droplets momentum and velocity.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.807-810
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• 2005

In this study, MMA-modified paste of coating material for protecting the concrete structures was developed. The coating material was applied to cement concrete specimens by brush, roller and spray in each of which one, two and three layers to survey, by the cold-hot iterative test, the neutralization test, the chloride ion permeation test and the ante-abrasion test, the affect of painting methods and layers influencing on the durability of coating material. Results of the cold-hot iterative test showed that, regardless of the painting methods and layers, the defects such as crack or fuzz on surface were not produced. As the number of painting layers increased, the neutralization prevention as well as the chloride ion permeation prevention effects were increased. On the other hand, no difference was found between the painting methods. Reducing weight by abrasion of polymer paste coating material was $20\%$ comparing to that of cement mortar.