• 한국재료학회지
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• 제30권11호
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• pp.581-588
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• 2020

Reducing CO₂ into high value fuels and chemicals is considered a great challenge in the 21st century. Efficiently activating CO₂ will lead to an important way to utilize it as a resource. This article reviews the latest progress of g-C₃N₄ based catalysts for CO₂ reduction. The different synthetic methods of g-C₃N₄ are briefly discussed. Article mainly introduces methods of g-C₃N₄ shape control, element doping, and use of oxide compounds to modify g-C₃N₄. Modified g-C₃N₄ has more reactive sites, which can significantly reduce the probability of photogenerated electron hole recombination and improve the performance of photocatalytic CO₂ reduction. Considering the literature, the hydrothermal method is widely used because of its simple equipment and process and easy control of reaction conditions. It is foreseeable that hydrothermal technology will continue to innovate and usher in a new period of development. Finally, the prospect of a future reduction of CO₂ by g-C₃N₄-based catalysts is predicted.

• 한국지열·수열에너지학회논문집
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• 제15권3호
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• pp.7-13
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• 2019

To improve the flow distribution at channel locations in the welded plate heat exchanger with "L"-type inflow, the flow visualization of Model 1 was carried out. Besides, the characteristics of flow distribution was investigated experimentally according to the header shape. The inlet flow rate for each channel location was increased at the side channels but decreased at the central channels. In the case of Model 2, which has a slant structure added to the basic header of Model 1, the unevenness of inlet flow increased by 23% from 0.019 to 0.023 as compared to Model 1. On the other hand, Model 3, which has a baffle structure added to Model 2, showed 0.064 unevenness in inlet flow, which was a 36% reduction one compared to Model 1. To improve the distribution at each channel in the welded plate heat exchanger with "L"-type flow, it is necessary to improve the header external shape for the guide of flow as well as the baffle structure for reduction of vortex flow.

• Journal of Ceramic Processing Research
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• 제20권3호
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• pp.222-230
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• 2019

Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. The morphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 ㎡/g. The doping of Fe ions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap (3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar light irradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancement than the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, and reduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion Ion Chromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.

• 한국세라믹학회지
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• 제32권7호
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• pp.777-782
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• 1995

The scale up production test for the hydrothermal synthesis of clay mineral from the anorthite, which is distributed in San Chung-District of Korea and called as the ground rock for halloysite-kaolin, has been investigated by using the gaitator type reactor. The automatic control system has been developed and applied for the more effective producibility and the reduction in the defect of this intermittent batch processing property, and finally for the feasibility of this system in actual use. It was observed that this agitator type reactor can reduce the synthesis reaction tme from 5 days to 3 days, only with the condition of 20rpm. The automatic control system could regulate the vessel temperature and pressure precisely at an optimum condition during the treatment. Therefore, from these test results the application-possibility for this system was found to be feasible in actual use.

• 한국지열·수열에너지학회논문집
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• 제10권4호
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• pp.1-7
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• 2014

This paper is performed to investigate of cooling effect and total enthalpy variation on EAHES(Earth-to-Air Heat Exchanger System) that is buried 3m depth and 60m length. Using EAHES, the reduction of the sensible heat is obviously but latent heat is showed increased trend. Although the outdoor average latent heat accounts for 53.2% of total enthalpy, latent heat of the exit air from EAHES was raised as 58%. For improving cooling effect of EAHES, it has to considered that how to remove the latent heat from EAHES.

• 마이크로전자및패키징학회지
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• 제20권3호
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• pp.11-18
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• 2013

Interest in copper nanoparticles has increased as an alternative for substituting silver nanoparticles because of its lower cost and less electromigration effect than silver. In this paper, the recent research trends and main results in wet-chemical synthesis of sub-100 nm Cu nanoparticles were summarized. The characteristics of synthesis were discussed with a classification such as modified polyol synthesis, modified hydrothermal synthesis, solvothermal synthesis, and the others, focussing on effects of capping agents, reductants, and pH. Information on the oxidation of synthesized copper nanoparticles were additionally commented.

• 한국지열·수열에너지학회논문집
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• 제16권4호
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• pp.16-23
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• 2020

In this study, the control characteristics and effects of control methods on heating performance and energy consumption for the hot water floor radiant heating control system of a residential apartment were research by experiment. As a control method, On-Off control and outdoor reset control methods with GRNN(General Regression Neural Network) and without GRNN are considered. Also, the control performances with regard to improvement of indoor thermal environment and reduction of energy consumption are compared, respectively. Experiment results show that the performance of the control method with GRNN is better than that of conventional on-off control method without GRNN in the responses of room set temperature and energy saving.

• Korean Chemical Engineering Research
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• 제45권5호
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• pp.448-454
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• 2007

미세 $BaTiO_3$ 분말의 합성을 위해 함수 티타니아와 수산화바륨을 원료로 수열합성 실험을 수행하여, 반응시간, 온도, 농도 변화에 따른 전화율, 결정구조 및 생성 분말의 물성을 조사하였다. 전화율에 미치는 영향은 시간 < 온도 < 농도 순이었으며, 2.0 M의 원료를 $180^{\circ}C$에서 2 h 수열합성 시킬 때 최대 전화율을 99.5%를 얻을 수 있었다. 낮은 농도(0.25 M)에서는 고온에서도 미반응 $BaCO_3$와 미반응 $TiO_2$ 생성을 피할 수 없었으며, 이 미반응 물질들은 고온에서 $BaTi_2O_5$를 생성시켜 불순물로 존재하였다. 농도를 높일수록 합성 $BaTiO_3$ 분말의 크기는 작아졌으며, 분말의 Ba/Ti 비도 1에 접근하였다. 2.0M 이상의 농도에서는 $180^{\circ}C$, 2 h 반응에서 Ba/Ti 비는 $1{\pm}0.005$ 이였다.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3707-3711
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• 2011

Silver nanoparticles coated with silica can be obtained by the reduction of $AgNO_3$ with hydrazine in the presence of NaOH-stabilized, active silicic acid (polysilicic acid). The size of the silver nanoparticles and the silica shell thicknesses were affected by varying the hydrazine content, the active silicic acid content and the experimental method (e.g. hydrothermal method). Typically, silver nanoparticles sized around 40 nm were aggregated, connected by silica. The presence of peaks centered around 400 nm in UV-vis spectra corresponds to the surface plasmon resonance of silver nanoparticles. The size of the aggregated silver nanoparticles increased with increasing hydrazine concentration. Under hydrothermal conditions at $150^{\circ}C$ the formation of individual silica particles was observed and the sizes of the silver nanoparticles were reduced. The hydrothermal treatment of silver nanoparticles at $180^{\circ}C$ gives a well-defined Ag@$SiO_2$ core-shell in aggregated silica sol particles. The absorption band observed at around 412 nm were red-shifted with respect to the uncoated silver nanoparticles (${\lambda}_{max}$ = 399 nm) due to the larger refractive index of silica compared to that of water. The formation of silver nanoparticles coated with silica is confirmed by UV-visible absorption spectra, transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) data.

• 한국식품저장유통학회지
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• 제21권4호
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• pp.544-548
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• 2014

본 연구는 환경 친화적인 새싹채소류의 고품질화를 위한 경제적이고 효율적인 살균기술을 개발할 목적으로 국내산 적무 종자의 다양한 열처리 방법에 따른 발아율과 미생물 저감효과를 조사하였다. 열수처리는 60, 65, 70, 75, 80, $90^{\circ}C$에서 각각 30, 60초간 실시하였고, 건열처리는 70, 80, 90, $100^{\circ}C$에서 5분간 실시하였다. 열수 처리에 따른 미생물의 제어효과는 시간에 따른 유의적인 차이는 보이지 않았으나, 온도변화에 따른 유의적인 차이를 나타내었다(p<0.001). $70^{\circ}C$ 이상의 온도에서 총세균수는 3 logs 이상의 감소를 보였으며, L. monocytogenes는 검출되지 않았다. 건열처리는 온도변화에 따른 유의적인 차이를 나타내었다(p<0.001). $100^{\circ}C$에서 5분간 처리한 후 총세균과 L. monocytogenes 수는 3 logs 이하 감소하였다. 열수처리에 따른 발아율의 변화는 처리 전과 후 모두 시간에 따른 유의적인 차이는 보이지 않았으나, $75^{\circ}C$ 이상의 온도에서 온도 증가에 따라 유의적으로 감소하였다(p<0.001). 한편, 열수처리 후 침지시킨 종자에서 발아가 더 촉진되는 것으로 나타났다. 건열처리에 따른 발아율은 $80^{\circ}C$ 이상의 온도에서 온도 증가에 따라 유의적으로 감소하였다(p<0.001). 건열처리한 후 증류수에 3시간 침지시킨 종자의 발아율은 $90^{\circ}C$ 이상의 온도에서 유의적으로 감소하였다(p<0.05). 결론적으로 적절한 열처리는 $75^{\circ}C$, 30분 이상의 열수처리하는 방법으로, 적무 새싹채소의 종자의 미생물학적 안전성을 증가시킴과 동시에 발아율을 증가시키는 것으로 판단된다.