• 한국세라믹학회지
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• 제27권5호
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• pp.661-667
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• 1990

Spinel powders were synthesized at the comparatively low-temperature range(800~90$0^{\circ}C$) by the emulsion-hot kerosene drying method and the effects of kerosene-evaporative conditions on powder characteristics were investigated. In emulsion drying, more unagglomerated and sinterable powders could be synthesized through rapid evaporation of emulsion at the higher kerosene temperature. The completion of formation reaction of spinel observed at the low-temperature range confirmed the high reactivity of powders. The relative theoretical density and the fracture toughness of spinel pellets sintered at 1$650^{\circ}C$ for 4hrs. were 98% and 2.1MN/m3/2, respectively.

• Food Science and Biotechnology
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• 제15권3호
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• pp.385-391
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• 2006

In Korea, different kinds of genetically modified (GM) crops are under development, including GM-rice expressing insecticidal crystal (Cry) proteins of Bacillus thuringiensis (Bt) modified to change a single amino acid. In this study, amino acid (aa) sequences of modified Cry proteins were compared to that of known allergens, and Cry proteins expressed in GM-rice were identified by using Cry protein specific polyclonal antibody. The antigen-antibody reactions were compared between GM and commercial rice to assess the allergic risk of Cry proteins. This analysis showed no known allergen to have more than 35% aa sequence homology with modified Cry proteins in Bt rice over an 80 aa window or to have more than 8 consecutive identical aa. Sera from allergic patients showed some IgE reactivity via immunoblotting and enzyme-linked immunosorbent assay (ELISA), although no differences were seen between GM and commercial rice. Based on these results we conclude that GM rice with modified Cry proteins has no differences in its protein composition or allergenicity relative to commercial rice.

• Bulletin of the Korean Chemical Society
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• 제21권10호
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• pp.1044-1046
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• 2000

Catalytic copolymerization of diethyl dipropargylmalonate (DEDPM) and phenylacetylene (PA) by Mo(CO)6 and (toluene) Mo(CO)3/chloranil has resulted in the expected copolymer consiting of a polyene backbone with five-and/or six-membered rings and th e PPA structure. Both complexes exhibited not only varying degree of catalytic activity depending upon the relative mole ratio of two monomers but also characterize the types of coploymers. The former yields the polyene backbone containing only five-membered rings as well as PA while the latter produces the polymers consisting of both five-and six-membered ring structure. Comparative studies show that Mo(CO)6 exhibits reactivity toward DEDPM alone, thus catalyzing initially metathesis cyclopoly-merization of DEDPM followed by copolymerization with PA while the (toluene)Mo(CO)3/chloranil system shows affinity for both PA and DEDPM.

• Bulletin of the Korean Chemical Society
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• 제5권5호
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• pp.179-182
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• 1984

MINDO/3 theoretical studies were carried out on sigmatropic hydrogen rearrangements in systems with central nitrogen atom; three systems studied being (1) N-methylformaldimine, (2) nitrous acid, and (3) formaldoxime-nitrosomethane systems. It was found that in system (1), 1,3-H shift is preferred whereas in systems (2) and (3), 1,2-H shifts are favored. The relative order of reactivity for the three systems was found to be (2) < (3) < (1), which is exactly the opposite to that found for the corresponding systems with central carbon atom.

• 한국가축번식학회지
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• 제10권2호
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• pp.168-174
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• 1986

These experiments were carried out to clarify the optimalconditions and interspecific cross reaction of H-Y antibody activity. H-Y antiserum was prepared in inbred SD female rats and Balb/c female mice by repeated immunization of rat newborn testis homogemate, rat and mouse spleen cells obtained from males of same strain. The activity of H-Y antibody in antiserum was tested by ELISA and biological tests. The cross reactivity of H-Y antibody was confirmed by culturing mouse and rabbit embryos in medium containing H-Y antibody and complement obtained from rat and guinea pig, respectively. The optimal condition for the activity of H-Y antibody was also investigated by culturing embryos in medium with different pH and complement concentration. The results obtained in these experiments were summarized as follows: 1. The formation rates of H-Y antibody in rats immunized with newborn testis and spleen cell were 40.0 and 50.0% respectively, and that in mouse immunized with spleen cell was 48.4%. 2. The activity of H-Y antibody was not affected by pH in range of 6.5 to 8.0, and the same was true for the relative concentration of complement to the H-Y antibody. 3. Minimum time needed for the activity of H-Y antibody was confirmed to be 0.5 to 1 hour and 24 to 48 hours respectively for the zona free embryos and intact embryos. 4. When mouse and rabbit embryos were treated with H-Y antibody obtained from rat, 46.4 and 54.8% of embryos were retarded or destroyed. From these results it could be said that H-Y antibody had strong interspecific cross reactivity.

• 한국대기환경학회지
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• 제15권4호
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• pp.417-428
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• 1999

The measurement of VOSCs(volatile organic sulfur compounds) in the air is nowadays a very important environmental research field. It is, however, very difficult because the concentration of the VOSC in ambient air is usually very low and the high reactivity makes it difficult to keep in container without loss of recovery. In this study, sampling method with cryogenic preconcentration is evaluated for analysis of atmospheric VOSC such as $CH_3SH,\;CH_3CH_2SH,\;CH_3SCH_3,\;CS_2,\;CH_3SSCH_3,\;CH_3SCH_2SCHA_3,\;and\;C_2H_5SSC_2H_5$ analyzed by GC-MS or GC-FID. Repeatabilities of measurement accompanied with preconcentration for 3-successive runs were in the range of 0.2~1.0% as a relative standard deviation. Stabilities up to 13 days were measured in 6 L canister and 10 L tedlar bag filled with VOSCs in ppb level. Higher stability was observed in tedlar bag as compared to canister with glass coated inner walls, and thiol compounds show dramatic losses in canister within 2~3 days. It is found that recovery over 70% was obtained in a week for all tested VOSCs when the compounds from ambient air matrix were stored in tedlar bag. It is also found that the stabilities of VOSCs are depending on humidity and coexisting compounds in matrix gas due to sample adsorption onto inner surface and reactivity. The results indicate the possibility and limitations of VOSC analysis in ambient air using container sampling method with cryogenic preconcentration.

• 대한화학회지
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• 제40권1호
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• pp.11-19
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• 1996

에너지기인 azido기($-CH_2N_3$), nitrato기($-CH_2ONO_2$)로 치환된 옥세탄의 단량체를 $BF_3$촉매하의 공중합에 관해서 반경험적인 MINDO/3, MNDO, AM1 그리고 HF/3-21G 방법 등을 사용하여 이론적으로 고찰하였다. 옥세탄 치환제와 $BF_3$ 이분자 착물의 입체적, 정전기적 구조를 이론적으로 설명할 수 있다. 옥세탄의 공중합 성장단계에서 반응성은 옥세탄의 반응중심 탄소의 양전하 크기와 옥세탄 성장단계의 친전자체의 낮은 LUMO에너지에 좌우됨이 예측된다. 옥세탄의 공중합 반응성비는 계산치와 실험값이 일치하는 랜덤 공중합 반응이다. 평형상태의 고리형 oxonium 이온과 열린 carbenium 이온의 농도 크기가 반응 메카니즘의 결정단계이며, 형태와 계산을 기초로하여 빠른 평형을 예상하여 볼 때 선폴리머 성장단계에서 $S_N1$ 메카니즘이 $S_N2$ 메카니즘보다 빠르게 반응할 것으로 예측된다.

• 보존과학연구
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• 통권33호
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• pp.85-97
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• 2012

이 연구는 문화재 보존환경 간이 측정법의 적용 및 활용 가능성 검토를 위한 기초연구로 자외선 지시카드의 성능을 검증하고 이를 바탕으로 일부 전시조명에서의 적용성을 검토하였다. 5종의 자외선 지시카드를 대상으로 온 습도 환경 및 자외선램프에 의한 반응도를 살펴본 결과, L 카드와 K 카드는 반응도가 매우 낮아서 환경 측정용으로 부적합한 것으로 나타났으며, M 카드는 습도의 영향을 받는 것으로 조사되었다. 그러나 S 카드는 반응성이 가장 좋고 자외선 저 방사 환경에서도 민감한 색도 변화를 보였다. S 카드를 주요 전시조명으로 활용되는 광원에서 노출평가를 실시한 결과, 자외선량이 높은 할로겐램프와 형광램프에서 큰 색차 값과 육안상의 뚜렷한 색변화를 관찰할 수 있었다. 따라서 자외선 지시카드 중 S 카드가 문화재의 전시조명 환경 점검 및 관리에 있어 간편하게 활용할 수 있을 것이다.

• Environmental Engineering Research
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• 제18권1호
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• pp.29-35
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• 2013

This study noted that the actual mechanism of N-nitrosodimethylamine (NDMA) photodecomposition in the presence of $H_2O_2$ is missing from the previous works. This study investigated a key unknown reactive species (URS) enhanced by the addition of $H_2O_2$ during the photolysis of NDMA with $H_2O_2$, not hydroxyl radicals. In order to provide experimental evidences in support of URS formation, we have mainly used p-nitrosodimethylaniline, methanol, and benzoic acid as well-known probes of ${\cdot}OH$ in this study. Both loss of PNDA and formation of hydroxybenzoic acids were dependent on NDMA concentrations during the photolysis in a constant concentration of $H_2O_2$. In particular, competition kinetics showed that the relative reactivity of an URS was at least identical with ${\cdot}OH$-like reactivity. In addition, the decay of NDMA was estimated to be about 65% by the direct UV light and about 35% by the reactive species or URS generated through the photolysis of NDMA and $H_2O_2$. Therefore, our data suggest that a highly oxidizing URS is formed in the photolysis of NDMA with $H_2O_2$, which could be peroxynitrite ($ONOO^-$) as a potent oxidant by itself as well as a source of ${\cdot}OH$.

• 한국음향학회지
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• 제21권8호
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• pp.708-718
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• 2002

본 연구에서는 진동-음향계에서 방사되어 생성된 일반 근접장에서 음향 인텐시티 기법을 이용해 소음원을 파악하는 방법의 문제점에 관하여 논한다. 이를 위해 자동차나중장비의 엔진실을 모사하는 3차원 구조물 모델을 고려한다. 실제 상황과 유사하도록 모델에는 음원들이 복잡한 형상의 표면에 상호 연관성이 있는 또는 없는 형태로 분포한다. 즉, 음원들은 음향학적으로 단단한 상자들에 의해 형성된 좁은 공간으로 연결되어 있다. 따라서 반사가 심한 음장에 면한 표면에 배치되어 있으며, 전체 구조의 바닥 부분은 하부의 바닥과 작은 틈새만큼 떨어져 있다. 음향 경계요소법을 이용하여 근접 음장과 내부 음장의 인텐시티를 계산한다. 주어진 음원들간의 상대적 위상, 주파수, 위치에 따른 효과를 조사하였고, 그 결과를 등인텐시티선도, 벡터도 및 에너지 유선으로 표현하였다. 현장에서 종종 행해지는 바와 같이, 예를들어 엔진룸 상부에서 인텐시티를 측정하여 음원을 조사하는 것과 같은, 반사장이 강한 음장에서 음향 인텐시티 기법을 적용하여 음원탐색을 시도할 경우 가짜 음원이 검색될 수 있음을 보였다. 이와 같은 음장에서 정확한 결과를 얻기 위해서는, 음원탐색 수행 전에 음장의 리액티비티에 대한 조사가 먼저 필요하며, 측정을 시행하기 전에 음장의 리액티비티를 없애거나 대폭적으로 줄이는 작업이 선행되어야 할 것이다.