• Journal of Soil and Groundwater Environment
• /
• v.11 no.2
• /
• pp.38-44
• /
• 2006

Two sulfur-based column reactors inoculated with a bacterial consortium containing autotrophic denitrifiers were operated for 100 and 500 days, respectively and nitrate removal efficiency and the adaptation of microbial communities in the columns were monitored with column depths and time. For better understanding the adaptation phenomenon, molecular techniques including 16S rDNA sequencing and DGGE analysis were employed. Although both columns showed about 99% of nitrate removal efficiency heterotrophic denitrifiers such as Cenibacterium arsenioxidans and Geothrix fermentans were found to a significant portion at the initial stage of the 100-day reactor operation. However, as operation time increased, an autotrophic denitrifier Thiobacillus denitrificans became a dominant bacterial species throughout the column. A similar trend was also observed in the 500-day column. In addition, nitrate removal efficiencies were different with column depths and thus bacterial species with different metabolic activities were found at the corresponding depths. Especially, T. denitrificans was successfully adapted and colonized at the bottom parts of the columns where most nitrate was reduced.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.4
• /
• pp.273-281
• /
• 2007

Hyperalkaline groundwater formed by groundwater-cement components and its reaction with bedrock in a nuclear waste repository were simulated by geochemical modeling. The result of groundwater-cement components reaction showed that the pH of water was 13.3 and the precipitated minerals were Brucite, Katoite, Calcium Silicate Hydrate(CSH1.1), Ettringite, Hematite, and Portlandite. The result of interaction between such minerals and groundwater sampled in Gyeongju area also showed that the pH of groundwater reached 12.4. Interaction between such hyperalkaline groundwater and granite was simulated by kinetic model during $10^3$ years. This result showed that the final pH of groundwater reached 11.2 and the variation of pH was controlled by dissolution/precipitation of silicate and CSH minerals. Groundwater quality was also determined by dissolution/precipitation of silicate, CSH, oxide minerals. Our results show that geochemical modeling of long-term hyperalkaline groundwater and rock interaction can contribute to the safety assessment of engineered barrier by predicting geochemical condition in repository site.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2004.05a
• /
• pp.309-311
• /
• 2004

수용성 양이온 안료인 RhB를 대상으로 회전원판 광촉매 반응기와 열처리와 비열처리 방법으로 코팅된 고정화 광촉매를 이용하여 색 제거실험을 수행한 결과 다음과 같은 결론을 얻었다. 1. 회전원판 광촉매 반응기의 경우 설치하는 회전원판의 개수가 증가하면 반응면적의 증가로 반응속도가 증가하지만 일정 거리이하로 설치되면 광과 원판과의 접촉이 방해받아 반응면적 증가 효과를 감소시키는 역할을 하며, 원판 사이의 최적 거리가 존재하는 것으로 나타났으며, 본 실험범위에서는 약 11.2 mm인 것으로 나타났다.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2003.05a
• /
• pp.297-302
• /
• 2003

국내 화학공업에 있어서 두드러진 특징중의 하나는 의약품, 염·안료 등과 같은 부가가치가 매우 큰 제품을 제조하는 정밀화학공업이 대부분을 차지하고 있으며, 반응기는 회분식으로 대상이 되는 공정의 반응조건 등을 제조자 스스로 결정해야 하는 것이 많아 오조작이나 열분해반응이나 폭주반응과 같은 이상반응 발생 시 조기 제어 미흡 등으로 인한 화재 폭발 등 중대사고가 발생할 위험성이 매우 크다. 실제로 회분식 반응기에 의한 사고가 빈번히 발생하였고 사고에 의한 피해도 심각하다.(중략)

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05c
• /
• pp.133-138
• /
• 1996

원자로의 중기발생기 재료로 사용되어온 Alloy 600에서의 규칙 반응에 대한 활성화 에너지 측정, aging에 따른 미세조직의 변화에 근거하여 입계 응력 부식 균열 기구를 검토하였다. Alloy 600에서는 약 50$0^{\circ}C$ 이하의 온도에서 aging 처리중 단범위 규칙 상의 존재 및 규칙 반응의 존재가 입증된 바 있다. 규칙 반응의 본성이 열적활성화 과정에 의한 것이라는 점, 규칙 반응에 대한 활성화 에너지의 크기와 입계응력부식균열의 활성화 에너지와의 유사성, 규칙 반응에 의한 쌍정의 형성, 쌍정의 형성에 기인한 결정내의 추가적 응력의 발생 등에 근거하여 Alloy 600에서 나타나는 입계응력부식균열 현상이 규칙 상의 형성과 관련되어 있음을 제안하였다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.295-300
• /
• 1997

백금족 원소인 Rhodium 과 Palladium 담지 SDBC 고분자촉매를 제조하여 삼중수소 분리반응 특성을 실험하였다. 수중에서도 고활성을 유지하는 소수성촉매 제조를 위하여 고수율의 벌크중합법에 의한 SDBC 고분자담체를 합성하였다. 삼중수소 분리반응실험은 수소유속과 반응온도를 촉매물질에 따라 변화 시켜서 반응효율을 측정함으로써 수행하였다. 실험결과 Rhodium-SDBC 와 Palladium-SDBC 공히 삼중수소 분리반응에 활성이 있는 것으로 나타났으며, 특히 Rhodium은 유망한 백금대체 촉매물질로 개발될 수 있음이 밝혀졌다.

• Geophysics and Geophysical Exploration
• /
• v.18 no.4
• /
• pp.232-240
• /
• 2015

Magnetotelluric (MT) survey investigates electrical structure of subsurface by measuring natural electromagnetic fields on the earth surface. For the accurate interpretation of MT data, the precise three-dimensional (3-D) modeling algorithm is prerequisite. Since MT responses are affected by electrical anisotropy of medium, the modeling algorithm has to incorporate the electrical anisotropy especially when analyzing time-lapse MT data sets, for monitoring engineered geothermal system (EGS) reservoir, because changes in different-vintage MT-data sets are small. This study developed a MT modeling algorithm for the simulation MT responses in the presence of electrical anisotropy by improving a pre-existing staggered-grid finite-difference MT modeling algorithm. After verifying the developed algorithm, we analyzed the effect of vertical transversely isotropic (VTI) anisotropy on MT responses. In addition, we are planning to extend the applicability of the developed algorithm which can simulate not only the horizontal transversely isotropic (HTI) anisotropy, but also the tiled transversely isotropic (TTI) anisotropy.

• Applied Chemistry for Engineering
• /
• v.30 no.3
• /
• pp.352-357
• /
• 2019

In this study, a reactive emulsifier with vinyl groups was synthesized by using 3-butenoic acid and polyoxyethylene(20) stearyl ether. The synthesized reactive emulsifier was confirmed by FT-IR and $^1H-NMR$. In addition, the reactive emulsifier synthesized in the preparation of aqueous acrylic pressure sensitive adhesives was used and the properties of the respective pressure sensitive adhesives were compared to those of using commonly used nonionic emulsifiers. The solid content was measured in the range of 56.8~57.4%. In the case of the initial adhesion, the S20BA made with a reactive emulsifier was measured as $^{\sharp}13$. Peel strengths of the prepared adhesives were measured in the range of $0.66{\sim}1.05kg_f$ and the highest peel strength was observed for S20BA. As a result of the heat resistance test, S20BA showed the highest as $840^{\circ}C$. In order to evaluate the applicability of adhesives for skin, the pH value was measured as 7, neutral and also it was found to be non-irritation from primary skin irritation test results.

• Journal of the Korean Data Analysis Society
• /
• v.20 no.6
• /
• pp.3015-3024
• /
• 2018

This study investigates the recent asymmetric effect of news on stock return volatility in Asian five stock markets - Japan, Korea, Singapore, Taiwan, and Malaysia - since 2000. This study uses the GJR-M model which shows a different effect of a good and bad news on volatility. Empirical results show that the unexpected negative return has a more crucial effect on stock return volatility than the unexpected positive one does in all five stock markets. This implies that the bad news of the stock markets gives a more remarkable effect on volatility than good news does. This study finds that it is very important for market participants and regulation practitioners to distinguish between positive and negative return shocks in the stock markets since bad news might have a larger impacts on volatility than good news.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.225-226
• /
• 2003

일시적 수용성 반응성 분산염료는 염료합성시에 분산제를 사용하지 않기 때문에 원가절감 및 밀링공정 생략에 의한 생산성 증대효과가 있다[1-2l. 또한 혼방섬유를 단일염료로 일욕에서 염색할 수 있기 때문에 공정단축의 효과, 염색공정시에도 분산제를 사용하지 않아도 되므로 조제절감 및 염색폐수의 환경문제 개선 둥의 장점이 있다. 3원색(yellow, red, blue)의 일시적 수용성 반응성 분산염료를 이용하여, Acetate/Nylon(A/N), Acetate/polyester(A/P), Polyester/Nylon(P/N) 혼방섬유를 일욕에서 염색하였으며, 염색성, 견뢰도 및 염색폐수의 환경성을 평가하였다. (중략)