• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.222-226
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• 1998

Borazine (B3N3H6) as an inorganic analogue of benzene was synthesized by reaction of cheap raw materials (NaBH4 and (NH4)2SO4), and by using simple glass reaction apparatus in a scale up to 20 g per run with highly improved yield over 50%. It appears that synthesis of borazine is competing with formation of poly(aminoborane) as an inorganic analogue of polyethylene. The synthesized borazine and its polymerized product were characterized by comparison with products obtained from a commercial one. Bulk pyrolysis of the borazine polymer to 1500 ℃ produced a pure boron nitride (BN) with 75% ceramic yield, which displayed good oxidation resistance under dry air.

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1789-1796
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• 2007

A ${\beta}$-glucosidase with the molecular mass of 160,000 Da was purified to homogeneity from cell extract of a cellulolytic bacterium, Cellulomonas uda CS1-1. The kinetic parameters ($K_m$ and $V_{max}$) of the enzyme were determined with pNP-cellooligosccharides (DP 1-5) and cellobiose. The molecular orbital theoretical studies on the cellulolytic reactivity between the pNP-cellooligosaccharides as substrate (S) molecules and the purified ${\beta}$-glucosidase (E) were conducted by applying the frontier molecular orbital (FMO) interaction theory. The results of the FMO interaction between E and S molecules verified that the first stage of the reaction was induced by exocyclic cleavage, which occurred in an electrophilic reaction based on a strong charge-controlled reaction between the highest occupied molecular orbital (HOMO) energy of the S molecule and the lowest occupied molecular orbital (LUMO) energy of the hydronium ion ($H_3O^+$), more than endocyclic cleavage, whereas a nucleophilic substitution reaction was induced by an orbital-controlled reaction between the LUMO energy of the oxonium ion ($SH^+$) protonated to the S molecule and the HOMO energy of the $H_2O_2$ molecule. A hypothetic reaction route was proposed with the experimental results in which the enzymatic acid-catalyst hydrolysis reaction of E and S molecules would be progressed via $SN_1$ and $SN_2$ reactions. In addition, the quantitative structure-activity relationships (QSARs) between these kinetic parameters showed that $K_m$ has a significant correlation with hydrophobicity (logP), and specific activity has with dipole moment, respectively.

• 약학회지
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• 제40권2호
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• pp.202-211
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• 1996

Experiments were performed on male Sprague-Dawley rats to investigate the immunobiological effects on route of administration of amygdalin(AM). Rats were administered orally at 12.5, 25, or 50mg/kg/day of AM or injected wtih 25,50, or 100mg/kg/day of AM intravenously for 2 weeks. Rats were immunized and challenged with sheep red blood cells(SRBC). The results of this study were summarized as follows;(1) In oral administration of AM, body weight gains were significantly increased by 50mg/kg AM as compared with controls, the relative weights of liver and thymus also were significantly increased by 12.5 and 25mg/kg AM. However, 2-mercaptoethanol-resistant hemagglutination titier (2-MER HA), Plaque forming cells (PFC) and rosette forming cells (RFC) were non-dose dependently decreased. Phagocytic activity and delayed-type hypersensitivity (DTH) reaction also were significantly decreased by 50mg/kg AM. (2) In intravenous injection of AM, body weight gains, hemagglutination titer (HA), 2MER-HA, DTH reaction, PFC, RFC and circulating leukocytes were not influenced by AM. However, the relative weights of liver, spleen and thymus were significantly enhanced 100mg/kg AM. These results indicated that oral administration of AM non-dose dependently suppresses humoral and cell-mediated immunity in SD rats, and that intravenous injection of AM is unaffected humoral and cell-mediated immunity, however, the high dose of it significantly enhances phagocytic activity.

• 한국세라믹학회지
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• 제56권5호
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• pp.497-505
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• 2019

Lanthanum-based transition metal cations containing perovskites have emerged as potential catalysts for the intermediate-temperature (600-800℃) oxygen reduction reaction (ORR). Here, we report a facile acetylacetone-assisted combustion route for the synthesis of nanostructured La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF6428) cathodes for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). The as-prepared powder was analyzed by thermogravimetry analysis-differential scanning calorimetry. The powder calcined at 800℃ was characterized by X-ray diffraction, scanning electrode microscopy, energy dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area measurements. It was found that the porosity of the air electrode significantly increased by utilizing the nanostructured LSCF6428 instead of commercial powder. The performance of a single cell fabricated with the nanostructured LSCF6428 cathode increased by 112%, from 0.4 to 0.85 W cm^-2, at 700℃. Electrochemical impedance spectroscopy showed a considerable reduction in the area-specific resistance and activation energy from 133.5 to 61.5 kJ/mol, resulting in enhanced electrocatalytic activity toward ORR and overall cell performance.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.766-771
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• 2012

폴리카보네이트(Polycarbonate (PC))는 전기, 전자, 자동차, 건축 등 여러 분야에 널리 사용되고 있는 엔지니어링 플라스틱으로 사용량이 점차 증가하고 있다. 일반적으로 PC는 bisphenol A (BPA)와 phosgene을 반응시켜 합성한다. 하지만 이 반응에서 사용되는 phosgene은 심각한 독성을 갖고 있어, 환경 안전 면에서 문제가 제기되고 있다. Phosgene을 대체하기 위해 DPC을 이용하는 공정이 제안되었다. DPC는 DMC (Dimethyl Carbonate)와 Phenol의 에스테르교환 반응에 의해 합성된다. PBO 촉매를 사용한 DPC 합성 반응에 대하여 반응온도, DMC/Phenol의 비 그리고 촉매 농도 변화가 반응 수율에 미치는 영향을 알아보았다. 또한 DPC 합성 반응에 대한 반응속도 모델을 구하였고 반응속도 모델이 예측한 값이 실험치와 잘 일치함을 보였다.

• 한국세라믹학회지
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• 제48권1호
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• pp.99-105
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• 2011

Lead titanate ($PbTiO_3$) powder was prepared from lead nitrate ($Pb(NO_3)_2$) and titania ($TiO_2$) by hydrothermal route. Phase formation process was investigated by observing the phases formed in various experimental conditions like different KOH concentration, reaction temperature and time. $PbTiO_3$ powder was fabricated when the KOH concentration was 0.8M or higher. An intermediate compound, $PbTi_{0.8}O_{2.6}$, was formed at first by a reaction between PbO and $TiO_2$ and changed into $PbTiO_3$ powder with a perovskite crystal structure. A $PbTiO_3$ phase was formed in a shorter time when a KOH concentration was increased from 0.8M to 8M because a driving force for a $PbTiO_3$ formation was increased due to an increase in a degree of supersaturation. And $TiO_2$ (rutile) and $3PbO{\cdot}H_2O$ were observed at room temperature in a 0.8M KOH solution and $TiO_2$(rutile) and PbO (litharge) in a 8M KOH. A $PbTiO_3$phase was also formed in a shorter time at a higher reaction temperature as a reaction temperature influenced the rates for a dissolution and a precipitation.

• 한국실내디자인학회논문집
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• 제19권6호
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• pp.197-205
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• 2010

For the spatial experience of spectators visiting a museum, the route search of trying to follow the spatial structure or production of exhibition and the information search of trying to see are accomplished at the same time. In such process, the spectator's reaction of visual perception produces the result of emotional reaction and action exchanged between human and space by going through the recognition and perception on the target of environment factor. For the spatial experience of a spectator, the reaction of visual perception which interacts according to the exhibit and exhibition environment within space according to viewing purpose, interest and concern of spectator comes out as visual activity which is an activity to understand the spatial information shown as various activities according to spatial structure and unfolding characteristics of the display. The purpose of this study is to identify The Correlation of Spectator Movement Created According to Structural Form of Exhibition Area Based on Interaction between Exhibition Area Structure and Spectator to utilize as basic material while designing museum exhibition using isovist field which is a quantitative analysis tool of spectator's visual behavior and spatial structure at each exhibition area.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.3055-3058
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• 2013

Methanesulfonic acid (MSA) was used as catalyst to remove trace organic sulfur (thiophene) from Fluid Catalytic Cracking gasoline (FCC) via alkylation with olefins. The reactions were conducted in Erlenmeyer flask equipped with a water-bath under atmospheric pressure. The influence of the temperature, the reaction time, and the mass ration of MSA were investigated. After a 60 min reaction time at 343 K, the thiophene conversion of 98.7% was obtained with a mass ration of MSA to oil of 10%. The catalyst was reused without a reactivation treatment, and the thiophene conversion reached 92.9% at the third time. The method represents an environmentally benign route to desulfur, because MSA could easily be separated from the reaction mixture via decantation and it could be reused.

• 대한의생명과학회지
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• 제27권4호
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• pp.255-263
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• 2021

Human Astrovirus (HuAstV) is an important gastrointestinal pathogen that is frequently reported worldwide. Monitoring of contaminated groundwater has been suggested since HuAstV is transmitted through the fecal-oral route. This study developed a test method based on conventional reverse transcription (RT)-nested polymerase chain reaction (PCR) that involves SL^® non-specific reaction inhibitor for unknown non-specific amplification taking place in the groundwater environment. An optimal method for detecting HuAstV in groundwater sample through analysis and comparison against conventionally reported method was also suggested. The developed method enabled the production of nested PCR amplicon of 630 nt, which is a sufficient length for similarity analysis based on sequencing and genotyping. Amplicons suspected to be HuAstV were amplified in two out of the twenty groundwater samples collected in Korea, presenting 99.77% and 99.73% similarity against HuAstV 1 strain lhar/2011/kor (JN887820.1) in sequencing, respectively. These amplicons were identified as HuAstV 1.

• 대한화학회지
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• 제27권6호
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• pp.449-456
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• 1983

방사선장해를 예방할 수 있는 특성을 지닌 티오인산 이수소 S-2-(${\omega}$-아미노알킬아미노)에틸들의 간편한 합성법을 연구하였다. 중간체인 3-(2-프탈이미도에틸)-2-옥사졸리디논을 프탈이미드 칼륨염과 3-(2-브로모에틸)-2-옥사졸리디논을 반응시켜 만들었으며, 이 브로모에틸의 옥사졸리디논 유도체는 디에탄올아민으로부터 만들어진 2,2-디브로모 디에틸아민과 탄산염 혼합물의 알카리성 고리닫기 반응으로 합성할 수 있었다. 이 중간체는 30% 브롬화수소(가스)-초산용액으로 반응시켜 브롬화수소 N-(2-(2-브로모에틸아미노)에틸)프탈이미드로 유도되었고 이것을 다시 브롬화수소-초산용액으로 반응시켜 이브롬화수소 N-(2-브롬화에틸)-1,2-에탄디아민을 얻을 수 있었다. 1,3-디아미노프로판과 2-클로로에탄올로부터 2-(3-아미노프로필아미노)에탄올을 합성하고 이것을 Cortese씨법으로 처리하여 이브롬화수소 N-(2-브로모에틸)-1,3-프로판아민을 얻었다. 이들 이브롬화수소들을 DMF 용매에서 티오인산 나트륨으로 처리하여 티오인산 이수소 S-2-(${\omega}$-아미노알킬아미노) 에틸들을 합성하였다. 각각의 합성과정의 특징을 반응조건 및 총수율과 관련시켜 논의하였으며 티오인산 유도체를 합성하는 각편한 방법을 제의하였다.