• Fire Science and Engineering
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• v.29 no.6
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• pp.1-5
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• 2015

In this study, the combustion characteristics of Hinoki Cypress Louver were measured after performing pressure impregnation with aqueous solution of boric acid, borax, and ammonium phosphate. The characteristics measured include ignition time, critical heat flux, and mass loss rate by incident hear flux (25, 30 and $50kW/m^2$). The samples used for the test were $100{\times}100{\times}10mm$, and the 5 min variation for each incident heat flux was measured 3 times. The results show that the ignition time for incident heat flux of $25kW/m^2$ showed a delay effect of 17.4 to 21.3% except for Type C-H. There was no significant difference at 35 and $50kW/m^2$ in the average mass loss rate in Types A-H and D-H, which had lower rates than Type N-H, which was predicted to be higher than that of Type N-H ($10.7kW/m^2$) by 38.22 to 60.46%. It is thus expected that at the time of initial primary fire, there would be a delay effect against fire spread.

• Clean Technology
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• v.28 no.4
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• pp.269-277
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• 2022

With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH₃- and CO₂-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.87-89
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• 1997

1. 서론 : 막을 이용한 분리기술의 실용화의 최대 과제는 선택성이 높고 용매의 투과용매의 투과속도가 높은 막재질 및 처리 면적이 큰 막의 개발이 필요하게 되었다. 이러한 성능 개발은 1960년대 cellulose acetate 계통의 막개발 이후 1980년대 지지층 고분자위에 다른 고분자 물질을 도포한 복합막(thin film composite layer)이 개발되어 막의 성능을 급격히 발전시켰다. 그 중에서 초박막화(ultrathin membrane)는 분리막에 의한 분리공정의 최대 결점인 낮은 투과량의 개선을 꾀할 수 있다는 장점 때문에 다양한 시도가 이루어지고 있다. 이러한 박막 제조 방법에는 박층분산법, 침지코팅법, 기상증착법, 계면중합법이 있으나, 섞이지 않는 두 계면 사이에서 고분자를 형성시키는 계면중합법은 수용상에 함침된 지지막위에 유기상을 계변에서 중합시켜 박막을 얻는 기술이다. 중합과정에서 일어나는 계면의 형성과정에 대한 연구는 미흡하기에 이에 본 연구는 시간에 따른 계면중합 반응 형성과정을 고찰하는 방법을 소개하고, 형성된 박막의 아론적, 실험적 두께 측정을 비교하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.353-356
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• 2006

Hardening of 2 component adhesive such as epoxy resin used in saturating FRP composite is triggered by mixing each component part within a batch. Chemical reactions occur explosively after a certain time after mixing the batch, viscosity and temperature rapidly increase. As a results, bond performance remarkably decreases and workability declines due to increase in viscosity. Therefore, adhesion should be completed before chemical hardening reaction is rapidly going on. This study examined pot life of structural adhesive for FRP composites by means of change in apparent viscosity and means of exothermic reaction temperature proposing in existing test standards. Result of each test method was compared and analyzed, and reasonable test method and evaluation method are suggested.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.387-390
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• 2008

Ni/MgAl 촉매상에서 LPG의 수증기 개질반응을 반응온도 $700{\sim}800^{\circ}C$, 공간속도 $20,000h^{-1}$, 수증기/탄소 비율 $1.0{\sim}3.0$인 조건으로 대기압하에서 수행하였다. 본 연구에서 사용된 촉매들은 공침법으로 제조하였으며, 하이드로탈사이트 구조에서 Ni-MgO 구조로 변환되는 과정에서 활성금속인 니켈이 고분산되는 장점을 지니고 있다. 제조된 촉매는 함침법으로 제조된 촉매보다 활성이 잘 유지되었으며 탄소침적에 대한 내구성 또한 향상되었으나 완벽하게 해결되지는 못하였다. 따라서 이와 같은 문제점을 해결하기 위해 귀금속이 modified된 Ni/MgAl 촉매를 제조하고 반응 특성을 비교하였다. Rh-Ni/MgAl 촉매는 LPG 수증기 개질 반응에서 1024시간동안 활성이 유지됨을 확인하였을 뿐만 아니라 탄소침적 또한 발생하지 않음을 확인하였다.

• Journal of Korea Foresty Energy
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• v.22 no.1
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• pp.24-29
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• 2003

Using woodceramics made from sawdust board of Larix leptolepis thinning logs, change in surface temperature were investigated, by the rate of resin impregnation and burning temperature. As the surface temperature of silicon rubber heater was going up, that of woodceramics also increase rapidly. Woodceramics made from under the condition of the rate of resin impregnation 70-80% and burning temperature 800-$1000^{\circ}C$, were higher than that of surface temperature. Also, it was found that woodceramics maintained heat for a long time because the descending velocity of their surface temperature was lower than that of the heater.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.28-30
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• 2007

본 논문은 변압기의 과부하 상태를 모의하고 내부 절연물의 잔존수명을 평가하기 위한 방법으로 열적 스트레스를 인가한 가속 수명 시험을 수행하여 광유 함침 절연지의 전기적 기계적 열화 특성을 분석하였다. 시험에 사용된 절연 재료는 변압기의 주 절연물로 널리 사용하고 있는 셀룰로스계 크래프트 절연지와 광유계 절연유를 사용하였다. 가속 열열화 시험은 IEEE/ANSI Standard C59.91-1981의 수명 예측 곡선에 의거하여 국내 배전환경에 부합하도록 $55^{\circ}C$ 절연시스템을 기준으로 하였으며, $150^{\circ}C$에서 약 1,000시간 동안 열 스트레스를 인가함으로써 변압기의 수명이 다하도록 모의하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.2
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• pp.136-140
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• 2002

The investment casting process is used frequently to manufacture precise and complex shape metal parts. The previous wax pattern manufacturing process takes long time and high costs because the process is performed by hands. In order to improve the wax manufacturing process, a new process is developed to manufacture the wax pattern by using a rapid prototyping system. A CastForm pattern is made by a Selective laser Sintering type RP with CastForm powder. The CastForm pattern is dipped in the melted wax liquid, and the melted wax penetrates into the pores of the CastForm pattern. Wax pattern is obtained after cooling the CastForm pattern slowly. A stainless steel part has been manufactured by the suggested process. By obtaining the suggested process the manufacturing time and costs are reduced largely and the accuracy is improved.

• Journal of Conservation Science
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• v.37 no.6
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• pp.821-830
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• 2021

The weapons excavated from the de-militarized zones (DMZ) of Korea are vulnerable to corrosion due to the immediate and drastic environmental change. Especially, the chloride ions (Cl^-) in iron weapons cause active corrosion and require removal. In this study, conservation treatment and de-salination was performed for the discovered weapons from excavation sites of soldiers killed in action during the Korean War. Furthermore, an attempt was made to prepare the most stable plan for conservation treatment through the comparative study of soaking weapons in distilled water without chemicals and in a solution of sodium (SSC) at different temperatures. In the preliminarily experiments, the comparison of the eluted Cl^- ions according to different conditions of de-salination showed that the highest number of ions were detected from the de-salination with SSC at a temperature of 100℃, and its duration was much smaller, i.e., 1~2 weeks. Accordingly, for the parts from the guns and rifles amongst other objects, a six-time de-salination was conducted in the SSC solution for 8 hours at 100℃ and subsequently, for 16 hours at room temperature during which the distilled water and SSC were exchanged every week. However, in the case of a loaded rifle, the de-salination was not conducted, considering the risk that the high temperature and pressure by impregnation in vacuum could cause an explosion

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.606-612
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• 2022

Relatively high indoor CO₂ concentration (>1,000 ppm) has a negative impact on human health. In this work, indoor CO₂ adsorbent was developed by impregnating KOH or K₂CO₃ on commercial activated carbon, named as KOH/AC and K₂CO₃/AC. Commercial activated carbon (AC) showed relatively high BET surface area (929 m²/g) whereas KOH/AC and K₂CO₃/AC presented lower BET surface area of 13.6 m²/g and 289 m²/g. Two experimental methods of TGA (2,000 ppmCO₂, weight basis) and chamber test (initial concentration: 2,000 ppmCO₂, CO₂ IR analyzer) were used to investigate the adsorption capacity. KOH/AC and K₂CO₃/AC exhibited similar adsorption capacities (145~150 mg_CO2/g), higher than K₂CO₃/Al+Si supports adsorbent (84.1 mg_CO2/g_sample). Similarly, chamber test also showed similar trend. Both KOH/AC and K₂CO₃/AC represented higher adsorption capacities (KOH/AC: 93.5 mg_CO2/g K₂CO₃/AC: 94.5 mg_CO2/g_sample) K₂CO₃/Al+Si supports. This is due to the KOH or K₂CO₃ impregnation increased alkaline active sites (chemical adsorption), which is beneficial for CO₂ adsorption. In addition, the regeneration test results showed both K-based adsorbents pose a good regeneration and reusability. Finally, the current study suggested that both KOH/AC and K₂CO₃/AC have a great potential to be used as CO₂ adsorbent for indoor CO₂ adsorption.