• 한국건축시공학회지
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• 제10권5호
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• pp.21-29
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• 2010

희생양극방식은 지하구조물이나 해양환경하에서 구조물의 방식공법으로 소개되어지고 있다. 1970년대 이후, 희생양극방식이 철근콘크리트 구조물에 적용되어지고 있다. 희생양극방식은 전세계적으로 1990년대 이후 그 유효성을 검증되었다. 그러나, 희생양극방식은 시공적이나 경제적인 약간의 문제점을 가지고 있다. 그 문제점을 해결하기 위하여 고 내구성 금속을 용사시키는 희생양극방식이 개발되었다. 양극재(아연, 알루미늄)를 금속용사로 도포하여 실험체를 제작한 후, 실험체의 부식전류를 측정하여 양극재의 방식성능을 확인하였다. 실험결과 철근 콘크리트 구조물을 대상으로 금속용사를 이용한 희생양극방식이 우수한 방식성능을 가지는 것을 알 수 있었다.

• 한국재료학회지
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• 제18권2호
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• pp.92-97
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• 2008

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders prepared at temperatures that were lower and higher than $700^{\circ}C$ had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of $Ca_2SiO_4$. The optimum flow rates of the carrier gas in the preparation of the $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

• 대한기계학회논문집B
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• 제34권11호
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• pp.1005-1013
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• 2010

본 연구는 HCCI 엔진의 운전조건을 고려한 혼합연료의 감압비등 분무제어방법을 평가하기 위하여 수행하였다. 2상영역이 존재하는 혼합연료는 고비점성분의 증발촉진과 함께 연료분무의 급격한 증발을 유도할 수 있는 감압비등분무를 이용함으로써 저온 및 저밀도장에서 혼합기형성과정의 제어가 가능하다. HCCI 엔진은 이러한 분위기조건에서 연료를 조기분사하기 때문에 착화성이 높은 경유와 휘발성이 높은 가솔린성분으로 함유한 혼합연료의 감압비등현상을 이용함으로써 액체연료의 분열, 미립화와 같은 물리적 제어 및 착화연소에 의한 화학적 제어를 실현할 수 있다. 본 연구는 혼합연료의 성분과 몰분율을 주요변수로 설정하여 정적용기 내에 분사된 연료분무의 감압비등현상을 슐리렌 화상 및 Mie 산란광을 촬영한 후, 화상처리과정을 통하여 이루어졌다. 그 결과로 감압비등현상은 비교적 저온 및 저밀도장에서 분무구조가 크게 변화함을 알 수 있었으며, 조기 연료분사시기에서 감압비등분무를 이용한 혼합기형성을 제어함으로써 HCCI 연소에 적용이 가능할 것으로 분석하였다.

• 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.

• 한국터널지하공간학회 논문집
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• 제19권3호
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• pp.551-565
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• 2017

차수용 박층 멤브레인은 폴리머를 주요 구성성분으로 하는 재료로서 높은 부착성능과 시공성을 특징으로 하는 방수 재료이다. 차수용 박층 멤브레인은 일반적으로 콘크리트 또는 숏크리트 라이닝과 일체화되어 복합 구조체 형태로 방수 기능을 발현하는 재료이다. 본 연구에서는 지하구조물의 대표적인 구조물인 터널에서 차수용 박층 멤브레인 타설이 가능한 콘크리트 라이닝 재료에 차수용 박층 멤브레인을 적용할 경우 콘크리트 라이닝의 거동 변화를 수치해석적 방법으로 검토하였다. 콘크리트 라이닝의 거동은 3점 휨 시험을 수행하는 것으로 가정하고 이때 발생한 하중-변위 관계를 통해 콘크리트 라이닝의 최대 휨 하중 변화와 항복 이후 변화를 검토하는 방법으로 연구를 수행하였다. 해석결과, 콘크리트 라이닝에 차수용 박층 멤브레인 시공을 통해 고려할만한 보강효과를 확인하였다.

• 한국세라믹학회지
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• 제32권4호
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• pp.462-470
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• 1995

The characteristics of spray-dried granules are important for dry pressing operation since they have great influences on die-filling, compaction ratio, and resulting green microstructure. An attempt was made to control granule morphology and the packing structure of fine Si3N4 particles in granules by adjusting suspension property. Mercury porosimetry was used to characterize the pore structures of both granules and green compacts. Finally, the effects of particle packing structure in granules and green microstructure on sintering behavior were investigated.

• 세라미스트
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• 제9권6호
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• pp.24-29
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• 2006

Electron beam physical vapor deposition (EB-PVD) process has currently been applied to thermal barrier coatings (TBCs) for aircraft engines. Due to unique columnar structure, EB-PVD TBCs have advantages in resistances to thermal shock and thermal cycle for their applications, compared to films prepared by plasma spray By the EB-PVD equipment, we successfully obtained yttria-stabilized zirconia (YSZ) layer which has columnar and feather like structure including a large amount of nano size pores and gaps. The EB-PVD technique has been developed for coating functional perovskite type oxides such as (La, Sr)MnO3. Electrode properties have been improved by interface and structural control.

• 한국입자에어로졸학회지
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• 제12권2호
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• pp.37-42
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• 2016

$CeO_2$ nanoparticles were prepared by a flame spray pyrolysis from aqueous solution of cerium nitrate. The morphology, structure crystallinity and specific surface area of as-prepared nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Telle (BET). The $CeO_2$ nanoparticles about 5 nm in diameter showed a cubic fluorite structure and polyhedral morphology. The average particle size increased as the cerium nitrate concentration increased. UV absorption performance of the as-prepared nanoparticles was measured by UV-visible spectroscopy. UV absorption of $CeO_2$ nanoparticles was more effective than that of commercial $TiO_2$ nanoparticles. Effect of dopants such as Ti and Zn to $CeO_2$ nanoparticles on UV absorption properties was also investigated. In case of $Ti/CeO_2$, and $Zn/CeO_2$ nanoparticles, they showed a little higher UV absorption values compared with $CeO_2$ nanoparticles. The as-prepared nanoparticles can be promising materials with high UV absorption value.

• 대한기계학회논문집B
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• 제30권7호
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• pp.682-691
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• 2006

This study was conducted to assess the effect of mixed fuel composition and mass fraction on spray inner structure in evaporating transient spray under the various ambient conditions. Spray structure and spatial distribution of liquid phase concentration are investigated using a thin laser sheet illumination technique on the multi-component mixed fuels. A pulsed Ar+ laser was used as a light source. The experiments were conducted in a constant volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. Used fuel contain $i-octane(C_8H_{18}),\;n-dodecane(C_{12}H_{26})$ and $n-hexadecane(C_{16}H_{34})$ that are selected as low-, middle- and high-boiling point fuel, respectively. Experimental conditions are 25Mpa, 42MPa, 72MPa and 112MPa in injection pressure, $5kg/m^3,\;15kg/m^3\;and\;20kg/m^3$ in ambient gas density, 400K, 500K, 600K and 700K in ambient gas temperature, 300K and 368K in fuel temperature, and different fuel mass fraction. Experimental results indicate that the more high-boiling point component, the longer the liquid phase it were closely related to fuel physical properties, but injection pressure had no effect on. And there was a high correlation between the liquid phase length and boiling temperature at 75% distillation point.

• 한국진공학회지
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• 제10권2호
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• pp.213-218
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• 2001

분무열분해법으로 유리기판 위에 ZnO와 ZnO:In 박막을 성장시켰다. 성장된 ZnO 박막은 hexagonal 구조를 이루고, 격자상수 a=3.242 $\AA$, c=5.237 $\AA$였고, (002) 방향으로 선택 성장되었다. In을 0~6.03 at. % 불순물로 첨가하여 성장시킨 ZnO:In박막은 ZnO 박막의 결정구조와 같고 격자상수가 약간 증가하였다. ZnO:In 박막의 금속 이온의 비는 분무용액의 금속 이온의 비와 거의 일치하였다. ZnO:In 박막의 최소 비저항과 최대 운반자 농도는 In를 2.76 at % 불순물로 첨가하여 성장시킨 경우였는데, 그 값은 각각 19.1 $\Omega\cdot\textrm{cm}$, $2.11\times10^{19}\textrm{cm}^{-3]$이었다. In를 3.93 at. % 불순물로 첨가하여 성장시킨 ZnO:In 박막 경우 400~800 nm 영역에서의 광투과율은 95% 이상이었다.