• 한국응용과학기술학회지
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• 제22권2호
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• pp.168-174
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• 2005

Aluminum tri-butoxide was mixed with the water/ethanol solution and then chloroplatinic acid was added to the solution. The solution was dried at $100^{\circ}C$ for 15hrs to remove the solvent and water then it was calcined at $500^{\circ}C$. The catalyst was activated with a gas mixture. During the activation, the temperature was increased from $150^{\circ}C$ to $500^{\circ}C$. The necessary amount of urea was dissolved in 50mL water and injected. Aqueous urea solution was then mixed with the feed gas stream. At low temperatures, nitrogen containing compounds of urea decomposition are used as reductants in the reducton of $NO_X$. However at high temperatures the nitrogen containing compounds are oxidized to NO and $NO_2$ by oxygen instead of being used in the reduction. The activity of the catalyst was dependent on urea concentration in the feed stream when there was not adequate water vapor in the feed. The maximum conversion was shifted from $250^{\circ}C$ to $150^{\circ}C$ when water concentration was increased from 2 to 17%. It seems that the maximum temperature shifts to lower temperatures because the hydrolysis rate of HNCO increases with water, resulting in higher amounts of $NH_3$.

• 한국응용과학기술학회지
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• 제30권3호
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• pp.494-503
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• 2013

In this study, $CO_2$ adsorbent was produced for minimizing energy loss due to ventilation within the building. For improved selectivity about low concentration of $CO_2$ in multiple-use facilities, the ball type adsorbent was modified from a commercial zeolite, alumina, alkali metals and activated carbon with mixing LiOH, binder, and $H_2O$. We measured specific surface area, pore characteristic, and crystal structure of the modified adsorbent. Effects of alkalization on the absorptive properties of the adsorbents were investigated. Continuous column tests (2,000 ppm) and batch chamber tests ($4m^3$, 5,000ppm) showed that the modified adsorbent indicated about the selectivity of $CO_2$ more than 9.7% (0.613 mmol/g) compared with ordinary adsorbents and $CO_2$ removal efficiency of 88.8% within l hour, respectively. It was estimated that the modified adsorbent was applicable to indoor environments.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.413-417
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• 2003

The last few decades have seen drastic growth in the use of brominated flame retardants(BFRs). There is the problems of polybrominated dibenzo-p-dioxins(PBDDS) and polybrominated dibenzofurans(PBDFs) generation as by-products in combustion process of BFRs. PBDDs/PBDFs are highlighted the new pollutants of environmental contamination, recently. In this study, the 10 kinds of PBDDs/PBDFs standards were used to perform the experiments of recoveries. The analysis of PBDDs/PBDFs in soil environmental samples. was carried out. In silica gel column cleanup, PBDDs/PBDFs eluted until 80mL of n-hexane, and the recovery was obtained 73∼105%. In multi-layer silica gel column cleanup, the recovery was obtained 56∼125% with various elution solvents. In alumina clean process, the standard mixture(PBDES, PBDDs/PBDFs) eluted the first fraction of 2% dichloromethane with n-hexane in the range of 0∼100mL, PBDEs compounds eluted in the second fraction of 50% dichloromethane with n-hexane. In activated carbon column cleanup, the PBBEs eluted to the first fraction(n-hexane) and second fraction(toluene), but PBDDs/PBDFs only eluted to the second fraction. The analytical methods of PBDDs/PBDFs for soil was established based on the experimental results of the environmental samples.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.387-392
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• 2001

When cavity floor is near the pulp, polymerization of light-activated restorations results in temperature increase. This temperature increase cause by both the exothermic reaction process and the energy absorbed during irradiation. Therefore instating base is required. Most frequently used insulating base is glass ionmer. The purpose of this study was to evaluate intrapulpal temperature changes of glass ionomer according to various curing intensity and curing time. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn for evaluating of temperature changes. glass ionomer material was placed in 2mm. total curing time was 40s: continuous 40s, intermittent 20s, intermittent 10s. Glass ionomer material was cured with 300mW/$\textrm{cm}^2$, 550mW/$\textrm{cm}^2$ light curing unit. The results were as follows : 1. Temperature in pulp increased as curing unit power is increased. 2. Temperature in pulp more increased continuous emission than intermittent emission.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.173-179
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• 2018

Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA-CC) separators for supercapacitor applications. The PVA-CC separators were fabricated by mixing various ceramic particles including aluminum oxide ($Al_2O_3$), silicon dioxide ($SiO_2$), and titanium dioxide ($TiO_2$) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA-CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the $PVA-TiO_2$ composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.

• 한국화재소방학회논문지
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• 제16권3호
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• pp.32-38
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• 2002

지구의 오존층 보호를 위해 폐기되는 $CF_3Br$재활용을 위해 $CF_3Br$을 원료로 $CF_3I$와 $C_2F_5I$의 합성연구를 수행하였다. 실험실규모의 $CF_3$I와 $C_3F_5I$의 합성실험장치에서 CuI, Kl, $K_2CO_3$, KF등의 금속염을 활성탄과 알루미나에 담지시킨 촉매를 사용하여 $400~600^{\circ}C$에서 반응을 실시하였다. 반응실험 결과 주생성물은 $CF_3I$와 $C_2F_5I$ 이며 미량의 $C_2F_6$, $CF_4$, $CF_2Br_2$등도 생성되었다. $CF_3I$합성촉매로는 활성탄에 7.5wt% KI와 $K_2CO_3$를 담지시킨 것이 가장 우수한 성능을 나타내었으며 $C_2F_5I 의 합성촉매로는 알루미나에 7.5wt% Cul를 담지시킨 것이 가장 우수하였다. 또한 최적 반응온도는 $500^{\circ}C$ 부근이었다.

• 산업경영시스템학회지
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• 제39권3호
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• pp.180-191
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• 2016

Optimizing energy usage for maximum efficiency is an essential goal for manufacturing plants in every industrial manufacturing sector. The generation and distribution of purifying compressed air is a large expense incurred in practically all manufacturing processes. Not only is the generation and treatment expensive equipment of compressed air, but frequent maintenance and effective operation is also required. As a plant's compressed air system is often an integral part of the production process, it needs to be reliable, efficient, and easy to be maintain. In this paper, we study to find operating method to save energy from the adsorption dryer in the process of purifying compressed air, which is required for a clean room production site in "A" company. The compressed air passes through a pressure vessel with two "towers" filled with a material such as activated alumina, silica gel, molecular sieve or other desiccant material. This desiccant material attracts the water from the compressed air via adsorption. As the water clings to the desiccant, the desiccant particle becomes saturated. Therefore, Adsorption dryer is an extremely significant facility which removes the moisture in the air $70^{\circ}C$ below the dew point temperature while using a lot of energy. Also, the energy consumption of the adsorption dryer can be varied by various operating conditions (time, pressure, temperature, etc). Therefore, based on existing operating experiments, we have searched operating condition to maximize energy saving by changing operating conditions of the facility. However, due to a short experiment period (from September to October), further research will be focused on considering seasonality.

• 공업화학
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• 제9권1호
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• pp.115-120
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• 1998

메타세시스에 높은 활성을 나타내는 고분산 레늄촉매을 제조하기 위한 레늄카보닐 침착의 표면화학 및 활성점 생성에 관하여 연구하였다. 알루미나는 773K(PDA)와 1223K(DA)에서 각각 처리하여 담체로 사용하였고, 메타세시스 활성은 순수한 프로펜을 사용하여 상압하의 298K에서 조사하였다. PDA상의 레늄 산화가는 상당히 높았으나, DA에서는 저산화가의 레늄으로 담지되어 있었다. 제조한 Re/DA촉매를 고온에서 열분해시킨 다음 저온에서 산소로 처리하면 메타세시스 활성이 나타났고, 그 활성은 극히 낮은 담지율에서도 Re/PDA이나 통상의 $Re_2O_7/Al_2O_3$촉매에 비해 높은 활성을 보여, 레늄 카보닐을 출발물질로 하고 DA를 사용하는 것이 효과적이었다. 열분해하여 얻은 Re/DA촉매상의 레늄이온은 알루미나의 산소원자 2개와 결합하여 2가를 가지고, 산소처리에 의하여 4가만큼 증가한 6가의 레늄이온이 되며, 메타세시스는 그 6가이온에 의해 생성된 카르벤착체를 통하여 진행됨을 알았다.

• 한국응용과학기술학회지
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• 제29권2호
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• pp.339-347
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• 2012

본 연구는 VOC 배출원 중 도장, 인쇄 공정에서 주요 발생물질인 톨루엔을 저온 분해할 수 있는 귀금속 팔라듐촉매 개발에 목적을 두고 있다. 팔라듐은 톨루엔 제거에서 활성이 우수하지만 비용이 높다. 따라서 실용성의 방안으로 Pd 담지량의 최소화 비율(0.1~1.0wt%)로 제조한 촉매의 활성을 측정하였다. 그 결과 1.0wt% Pd(R) 촉매가 모든 조건에서 가장 높은 활성을 나타내었다. 이는 SEM 촬영과 XRD 분석을 통해 촉매 제조과정에서 Pd의 담지량 및 소성 분위기에 따른 분산 형태와 연관이 있는 것으로 사료된다.

• 대한화학회지
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• 제33권4호
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• pp.350-356
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• 1989

타르, 니코틴 등 몇 가지 연초 에어로솔 성분의 흡착거동을 해석한 결과 비교적 저비점 피흡착질의 흡착률은 축적 동공부피의 증가와 더불어 증가하였다. 반면 비교적 고비점 피흡착질의 흡착률은 보다 작은 반경의 동공부피가 증가할수록 감소하였다. 여기에 사용된 흡착제는 활성탄, 실리카겔, 알루미나 및 활성백토이었다. 비표면적이 큰 흡착제가 보다 큰 흡착률을 가진다는 일반적인 경향은 고비점 피흡착질에 대해서는 성립되지 않았다. 이상의 결과는 위의 흡착거동을 탈착등온식을 기초로 하여 동공부피분포와 관련시켜 검토하므로써 얻어진 것이다.