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Wavepacket Correlation Function Approach for Nonadiabatic Reactions: Quasi-Jahn-Teller Model
Park, Heesoo,Shin, Changkyun,Shin, Seokmin Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.4
Time-dependent formulations of the reactive scattering theory based on the wavepacket correlation functions with the M${\phi}$ller wavepackets for the electronically nonadiabatic reactions are presented. The calculations of state-to-state reactive probabilities for the quasi-Jahn-Teller scattering model system were performed. The conical intersection (CI) effects are investigated by comparing the results of the two-surface nonadiabatic calculations and the single surface adiabatic approximation. It was found that the results of the two-surface nonadiabatic calculations show interesting features in the reaction probability due to the conical intersection. Single surface adiabatic calculations with extended Born-Oppenheimer approximation using simple wavepacket phase factor was found to be able to reproduce the CI effect semi-quantitatively, while the single surface calculations with the usual adiabatic approximation cannot describe the scattering process for the Jahn-Teller model correctly.
Park, Heesoo,Lee, Jin Yong,Shin, Seokmin American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.37
<P>The influence of pyridine adsorption and the applied electric field on the band structure and metallicity of zigzag graphene nanoribbons (ZGNRs) was investigated by using density functional theory (DFT) calculations. The semiconducting ZGNRs became half-metallic or remained semiconducting depending on the configuration of N–C covalent bonds between pyridine and the outermost C atom of the ZGNRs. In addition, the band gap of the α- and β-spin states of the ZGNRs could be tuned by noncovalent bonds. This effect was enhanced when BF<SUB>3</SUB> was introduced simultaneously at the opposite edge. The applied external electric field also modulated the band structures of the ZGNRs, making them half-metallic or semiconducting to some extent. These features suggest that the well-arranged adsorption of pyridine and BF<SUB>3</SUB> could be used to tune the band structures of nanoscale electronic devices based on graphene.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-37/jp3046824/production/images/medium/jp-2012-046824_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3046824'>ACS Electronic Supporting Info</A></P>
Heesoo Kim,Dong Ryul Park*,정지철,이상봉,Sunyoung Park,송인규 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA- 15 and polypyrrole as a templating agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site for the immobilization of [PMo10V2O40]5−. By taking advantage of the overall negative charge of [PMo10V2O40]5−, H5PMo10V2O40 (PMo10V2) catalyst was chemically immobilized on the N-MC support as a charge-matching component. Characterization results showed that nitrogen in the N-MC played an important role in forming a nitrogen-derived functional group (amine group), and PMo10V2 catalyst was finely and chemically immobilized on the nitrogen-derived functional group of N-MC support. In the vapor-phase selective conversion of methanol, the PMo10V2/N-MC catalyst showed a higher conversion of methanol than the bulk PMo10V2 catalyst. Furthermore, the PMo10V2/N-MC catalyst showed a higher selectivity for dimethoxymethane (a product formed by bifunctional oxidation-acid-acid catalysis) and a higher selectivity for methylformate (a product formed by bifunctional oxidation- acid-oxidation catalysis) than the PMo10V2 catalyst. Reaction pathway for selective conversion of methanol to dimethoxymethane over PMo10V2/N-MC catalyst could be controlled by changing the methanol feed rate.
Computational Study on Removal of Epoxide from Narrow Zigzag Graphene Nanoribbons
Park, Heesoo,Lee, Jin Yong,Shin, Seokmin American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.46
<P>We performed computational studies on the removal of an epoxide group from oxidized zigzag graphene nanoribbons (ZGNRs). Using density functional theory (DFT) calculations, we investigated the reaction mechanisms for the two competing processes, migration and reduction of an epoxide group in the middle of a narrow ZGNR. We found that the relative magnitudes of the barriers for migration and reduction depend on the width of the ZGNR. The reaction barrier for the reduction of an epoxide by CO decreased as the width of the ZGNR increased, while the barrier for migration showed the opposite trend. Moreover, the transition state energies for migration and reduction decreased upon the applied electric field perpendicular to the surface of the ZGNR. Our results illustrate that the removal of an epoxide from a ZGNR by reduction with CO can be facilitated by the application of an external electric field. For narrow ZGNRs, epoxide migration to neighboring sites may compete with the reduction reaction.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-46/jp508322z/production/images/medium/jp-2014-08322z_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp508322z'>ACS Electronic Supporting Info</A></P>
UV and storage stability of retinol contained in oil-in-water nanoemulsions
Park, Heesoo,Mun, Saehun,Kim, Yong-Ro Elsevier 2019 Food chemistry Vol.272 No.-
<P><B>Abstract</B></P> <P>This study was performed to examine the stability of retinol contained within oil-in-water (O/W) emulsions under UV and during storage at different temperatures. O/W emulsions were prepared using different emulsifiers and oil concentrations. The stability of the retinol contained in the O/W emulsions was investigated by measuring the percentage of residual retinol in the samples after UV exposure and storage at different temperatures (4, 25, and 40 °C). The oil concentration of the emulsion had a greater impact on UV stability than the type of emulsifier used, whereas the storage stability at different temperatures was affected by both the choice of emulsifier and the oil concentration. The storage stability of the retinol contained in the O/W emulsions may be related to the lipid oxidation properties of the emulsions rather than the latter’s physical stability. Experiments with EDTA and different oil types were performed to confirm this theory.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Turbidity of emulsions affect UV stability of retinol contained in the emulsion. </LI> <LI> Long-term stability of retinol might be related to chemical stability of emulsion. </LI> <LI> WPI-emulsion had poor retinol retention rates due to factors that promote oxidation. </LI> </UL> </P>
비점오염물질 저감을 위한 가정용 소규모 빗물 정원 연구
박희수(Heesoo Park),김성표(Seong-Pyo Kim) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-
도시의 개발사업에 따른 불투수면 확애로 인해 비점오염물질로 인한 4대강의 비점부하율은 1998년에 약 27%에서 2010년에는 약 68%로 증가하였으며 2020년에는 약 72%까지 증가될 것으로 전망된다. 본 연구에서는 이러한 비점오염물질의 증가율을 저감시키기 위해 가정용 소규모 빗물 정원의 연구가 필요하다고 보고 연구를 진행하였다. 본 연구에서 사용된 여재 및 식생은 가정에서 구하기 쉬운 것으 로 선택하였다. 여재는 자갈 5mm/10mm, 톱밥, 모래, peatmoss를 사용하였으며 식생으로는 창포, 잔디 를 선택하였다. 빗물 정원은 자갈 10mm, 톱밥, 모래(Type A), 자갈 5mm, 우드칩, 모래(Type B), 자갈 10mm, 잔디, 모래(Type C), 자갈 10mm, 창포, 모래(Type D), 자갈, 잔디, 모래 + paetmoss(Type E) 로 구성하였고 초기 오염물질의 농도는 T-N 12.6mg/L, T-P 2.5mg/L, COD 9mg/L로 하였다. 오염물 질 제거율이 가장 높은 빗물 정원은 Type E로 확인되었으나 전반적으로 제거율이 낮게 나타나 더 높 은 오염물질 제거율을 위해 추가 실험이 필요하다고 보인다.
박희수(Heesoo Park),이종욱(Jongwuk Lee) Korean Institute of Information Scientists and Eng 2018 정보과학회논문지 Vol.45 No.10
Skyline query is a preference query that finds a candidate set for user preferences, employing the dominance property. It can be effectively used for decision problems that have multiple data attributes. However, a problem arises whereby the skyline becomes too large as the number of attributes in the data increases. To solve this problem, in this paper, we propose a new algorithm for a linear skyline query that restricts a user’s preference function by a linear function. In the previous work, a method was proposed to obtain a linear skyline by adding the same number of virtual points to the data as the number of attributes. However, it has been observed that this previous method does not guarantee the correctness of the linear skyline. We revised this method by adding virtual points in order to find the correct linear skyline. We prove that the proposed algorithm finds the correct linear skyline, and we empirically evaluate the correctness of the proposed algorithm.