• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.709-714
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• 2002

To investigate the decomposition kinetics of poly(ethylene terephthalate) the high pressure molten-polymer injector has been devised. Using the experimental apparatus equipped with batch reactor and high pressure molten-polymer injector the decomposition of PET has been performed at constant pressure of 250 bar and 300, 320, $340^{\circ}C$, respectively. At each temperature conditions the conversions after initial 1 minute have shown very high values such as 76-90%. As the temperature increases the conversion reaches more than 98% at 10 minutes. Based on the second order reaction model the reaction rate constants have been obtained. We can calculate the conversions within 2% errors utilizing optimized rate constants. The activation energy for the decomposition of PET at subcritical conditions has shown to be 54.4 kJ/mol.

• Clean Technology
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• v.9 no.3
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• pp.125-132
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• 2003

Activity improvement of Ni metal catalysts for carbon dioxide reforming was studied using HY-zeolite as the main supporter. As the reaction temperature increased, $CH_4$ and $CO_2$ conversions increased, and conversions higher than 80% was obtained above $700^{\circ}C$. As the Ni loading increased, the catalyst activity increased, and the highest activity was shown for the Ni loading of 13wt%. The HY-zeolite support showed the highest intial conversions of $CH_4$ and $CO_2$, but it showed faster deactivation than a ${\gamma}-Al_2O_3$ support. Nevertheless, it maintained the $CH_4$conversion higher than 80% after 24 hr reaction. The effect of promoters such as Mg, Mn, K, and Ca was also studied. It was observed that the Mg promotor exhibited the highest catalyst activity and less deactivation compared with Mn, K and Ca. After 24hr reaction, The optimum Mg content was found to be 5wt%.

• Polymer(Korea)
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• v.24 no.3
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• pp.287-298
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• 2000

In preparing micron-sized monodisperse polystyrene beads by dispersion polymerization, the conversion, and the particle size and its distribution were affected by the reaction temperature, concentration of the monomer, solvent and initiator, molecular weight and concentration of the steric stabilizer, amount of oxygen existing in the reactor, and an appropriate combination of these starting materials. Ethanol as a dispersing agent, styrene as a monomer, PVP as a steric stabilizer, AIBN as an initiator, DVB as a cross-linking agent and toluene as a co-solvent were the basic materials for the synthesis. The reaction rate and the conversion were increased with the reaction temperature and the amount of DVB from 1 to 4%, and the conversion was saturated after 10 hours of the reaction time. The optimum reaction recipe for the preparation of the monodisperse PS beads was 25% styrene monomer, 0.5% DVB, 25% toluene, 10-15% PVP, and 2 and 4% AIBN, thereby, 3.9~4 ${\mu}{\textrm}{m}$ and 3.4~9.3 ${\mu}{\textrm}{m}$ of polystyrene beads, respectively, were successfully synthesized.

• Analytical Science and Technology
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• v.16 no.6
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• pp.431-437
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• 2003

Metalization yield of uranium oxide to uranium metal from lithium reduction process of spent pressurized water reactor (PWR) fuels was measured using thermogravimetric analyzer. A reduced metal produced in the process was divided into a solid and a powder part, and each metalization yield was measured. Metalization yield of the solid part was 90.7~95.9 wt%, and the powder being 77.8~71.5 wt% individually. Oxidation behaviour of the quartemary alloy was investigated to take data on the thermal oxidation stability necessary for the study on dry storage of the reduced metal. At $600{\sim}700^{\circ}C$, weight increments of alloy of Mo, Ru, Rh and Pd was 0.40~0.55 wt%. Phase change on the surface of the alloy was started at $750^{\circ}C$. In particular, Mo was rapidly oxidized and then the alloy lost 0.76~25.22 wt% in weight.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.120-125
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• 1998

A plasmid pNPG contains a genomic DNA complementing npgA1 which is located on the left arm of linkage group I. It transformed Aspergillus nidulans at a high frequency. No abortive transformants were observed and the $Trp^+$ transformants were all $Npg^+$. The 10.4 kb Psti fragment of the genomic DNA was subcloned into pILJ16, which increased the transformation efficiency by more than 200-folds. The transformants were mitotically unstable and yielded $Arg^-$ conidia at the frequency of more than 80%. An additional gene cloned into the plasmid containing the fragment was always lost with $argB^+$ marker. These characteristics strongly indicate the possibility that the plasmids autonomously replicate. The full activity of enhanced transformation was retained on the 4.9 kb EcoRI-HaeIII fragment. The DNA segment was similar to AMA1 rather than ANS1 in function and designated AMA2.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.452-454
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• 2012

본 논문에서는 열분해 및 촉매반응의 의한 Hydrazine의 Ammonia 전환율을 연구하였다. 원자력발전소 2차 계통은 물/증기 순환계통으로 기기 및 배관의 부식을 억제하고, 증기발생기(Steam Generator, SG)의 부식생성물 유입을 최소하기 위해 전휘발성처리법(All Volatile Treatment, AVT)을 적용하여 계통수의 pH를 약염기성으로 유지하고 있다. 또한 Hydrazine을 이용하여 계통수의 용존산소제거 및 환원성 분위기를 유지하고 있다. 현재 사용되는 AVT는 대부분 단일 아민(Ammine)으로 계통 전 영역에서 pHt를 약염기성으로 유지하기 어렵다. 따라서 복합 아민을 이용하여 단일 아민의 상호단점을 보완한 수처리법을 적용해야한다. 하지만 복합 아민을 적용할 경우 추가 아민 주입설비, 설치부지, 시설유지보수 및 관리가 요구되므로 기존 주입약품을 이용하여 아민을 공급할 수 있는 연구가 필요하다. 따라서 본 연구에서는 Hydrazine의 열분해 및 촉매반응을 이용한 Ammonia 전환율을 조사하였다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.526-529
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• 2007

본 연구에서는 일정선량(600kGy)에서 전자빔 에너지(0.7, 1, 2 MeV)를 달리하여 조사한 $Ni/g-Al_2O_3$ 촉매를 이용하여 세 가지 다른 종류의 합성가스 전환반응(메탄의 이산화탄소 개질반응, 메탄의 수증기 개질반응, 메탄의 부분산화반응)을 수행하였다. 전자빔 조사는 He 분위기, 실온에서 수행하였으며, 조사된 촉매의 표면상태 변화를 살펴보기 위하여 XRD, XPS 분석을 수행하였다. 고에너지 전자빔 처리된 $Ni/g-Al_2O_3$ 촉매의 표면 특성분석 결과 촉매 표면의 Ni종은 metallic Ni, NiO, $NiAl_2O_4$의 3가지 상태로 존재함을 알 수 있었으며, 전자빔 에너지 증가에 따라 촉매 표면의 전체적인 Ni 함량과 촉매 표면의 Ni 분산도를 나타내는 Ni/Al ratio가 증가하였다. 또한, 전자빔 에너지 증가에 따라 Ni에 결합된 산소가 더 크게 감소되어 표면에서 산소 vacancy가 증가하는 결과를 가져왔으며, 이는 결국 세 가지 Ni의 상태 중 metallic Ni과 $NiAl_2O_4$를 증가시켰다. 이러한 결과들은 메탄의 이산화탄소 개질 반응과 메탄의 수증기 개질반응에서 반응물($CH_4$, $CO_2$)의 전환율과 생성물(CO, $H_2$)의 수득율을 증가시켰으며 메탄의 부분산화반응은 반응의 특성상 메탄의 전환율은 증가하나 생성물인 CO, $H_2$는 오히려 감소하는 결과를 가져옴을 알 수 있었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.373-376
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• 2010

The characteristics of thermal-resistance catalyst for $N_2O$ propellant decomposition were studied in the present study. Si was added to the $Al_2O_3$ support to stabilize its surface area at high temperature (> $1000^{\circ}C$). Ru was used as a catalyst for $N_2O$ decomposition. The prepared catalysts were characterized using SEM, EDS and XRD analysis, and $N_2O$ conversion was measured as reaction temperatures. The Ru/$Al_2O_3$-Si catalyst showed better performance than Ru/$Al_2O_3$ catalyst.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.97-105
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• 2007

This study was conducted to compare the performances of acidogenic fermentation and hydrogen fermentation using bench-scale leaching-bed reactors for organic solid waste. Acidogenic fermenters were operated with dilution rates (D) of 2.0, 3.0 and $4.0d^{-1}$ after employing anaerobic sludge and hydrogen fermenters were operated with D of 2.0, 4.0 and $6.0d^{-1}$ after employing heat-treated anaerobic sludge. The highest chemical oxygen demand (COD) conversion efficiency (56.2%) was obtained in acidogenic fermentation with D of $3.0d^{-1}$. Only volatile fatty acid (VFA) was produced as a metabolite. On the other hand, hydrogen fermentation did not show higher COD conversion efficiency (49.3%) than acidogenic fermentation, but it produced hydrogen gas (5.1% of total COD) which was a clean and environmentally friendly fuel with a high energy yield. Therefore, either acidogenic fermentation or hydrogen fermentation could be applied to organic solid waste depending on the purpose of treatment, which could maximize the economics of anaerobic treatment.

• Journal of Korean Society of Transportation
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• v.31 no.3
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• pp.33-44
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• 2013

Personal Rapid Transit(PRT) has emerged as a promising transportation mode for transit-oriented sustainable communities. In this study, an alternative design of questionnaire survey is proposed in order to capture traveler's perception of an unexperienced transportation mode. This study aims at predicting the mode choice diversion behavior of potential PRT users who do not have experience of using it previously, considering their willingness-to-pay. The proposed model was applied to predict an aggregate forecast of PRT patronage for the city of Songdo where PRT is considered to be constructed. For validation of the proposed model, the price elasticity of PRT demand was analyzed, compared with existing models. The analysis results suggest that the proposed design of questionnaire survey is able to capture respondents' attitude and perception to unexperienced transportation mode in an effective manner. Also, they show that the proposed diversion rate model is more realistic than existing models in explaining the effects of users' willingness-to-pay for predicting PRT patronage.