자외선 조사에 의한 피부조직 단백질의 산화에 관한 연구

차승훈,정영도,이승철,안봉환,김영표,이민화 한국노화학회 1991 한국노화학회지 Vol.1 No.1

티타늄 함유 제올라이트 베타 촉매의 합성, 물성조사 및 반응특성 연구

윤보상,안화승 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.1

티타늄 함유 제올라이트 베타(Ti-beta) 촉매를 5가지 수열합성 방법과 알콕사이드 또는 메탈로센을 티타늄 원으로 이용한 2가지 후처리 grafting방법으로 제조하여 제조 방법에 따른 물성 차이를 연구하였다. 모든 촉매의 UV-Vis 스펙트럼에는 제올라이트 격자구조 내에 고립되어 존재하는 티타늄에 해당하는 220㎚의 흡수밴드가 관찰되었으며, grafting 시킨 경우 나노크기의 TiO_2 cluster에 기인하는 240-320㎚의 흡수 밴드가 함께 관찰되었다. 결정 입자는 dry-gel 방법과 seed를 사용한 경우 50㎚이하, 액상 전구체의 수열합성에 의한 기존 방법이나 TiO_2/SiO_2 xcrogel 전구체를 사용한 경우는 200㎚, 불산 분위기 합성에서는 2-5㎛의 평균 입자 크기를 나타내었으며, 분자체 결정에 대한 수율은 Ti-beta(F^-)>Ti-veta(seed)>Ti-Al-beta(xerogel)>Ti-Al-beta(dry-gel)>Ti-Al-beta(conventional)의 순서로 조사되었다. Cyclohexene의 epoxidation 반응은 Ti-Al-beta(conventional), Ti-beta(seed)>Ti-Al-beta(xerogel), Ti-Al-beta(dry-gel)>Ti-beta(F^-)의 순서로 전화율이 나타났으며, epoxide에 대한 선택성은 Ti-Al-beta(xerogel)<Ti-Al-beta(conventional)<Ti-Al-beta(dry-gel)<Ti-beta(seed)<Ti-beta(F^-)의 순서로 증가하였다. Epoxide의 선택성은 알루미늄 함량과 표면의 소수성 정도에 영향을 받음을 확인할 수 있었다. Cyclohexene의 전화율과 epoxide의 선택성은 모든 촉매에서 CH_3CN을 용매로 사용할 때가 CH_3OH보다 높게 나타났다. A critical evaluation of synthesis recipes reported for the large pore zeolite Ti-beta was conducted after a series of titanium containing zeolite beta were prepared by five different hydrothermal synthesis and in two post-synthetic grafting methods using alkoxide or metallocene as a titanium precursor. All Ti-beta prepared by different synthesis routes showed a narrow charge transfer band centered at ca. 220㎚ in UV-Vis spectra, typical of Ti sites isolated in zeolite framework. For those prepared by grafting, the absorption band at 240-320㎚ attributed to nano-sized TiQ clusters were also detected. Particle size of Ti-Al-beta(dry-gel) and Ti-beta(seed) were below 20㎚; Ti-Al-beta(conventional) and Ti-Al-beta(xerogel) below 200㎚; and Ti-beta(F^-) ca. 2-5㎛. Yield of zeolite crystals decreased in the order Ti-beta(F^-)>Ti-veta(seed)>Ti-Al-beta(xerogel)>Ti-Al-beta(dry-gel)>Ti-Al-beta(conventional). For cyclohexene epoxidation, conversions varied in the order Ti-Al-beta(conventional), Ti-beta(seed)>Ti-Al-beta(xerogel), Ti-Al-beta(dry-gel)>Ti-beta(F^-)> with epoxide selectivity in the order Ti-Al-beta(xerogel)<Ti-Al-beta(conventional)<Ti-Al-beta(dry-gel)<Ti-beta(seed)<Ti-beta(F^-). The epoxide selectivity was affected by aluminum content and hydrophobicity of the material. Cyclohexene conversions and epoxide selectivities were higher in aprotic CH_3CN solvent than in CH_3OH.

재난관리 행정에 대한 네트워크적 분석

박석희,노화준,안대승 서울대학교 행정대학원 2004 行政論叢 Vol.42 No.1

우리나라에서 재난관리행정(disaster management system)에 대한 논의는 대부분 지엽적이고 기술적(technical)인 측면에서만 이루어지고, 재난관리행정의 본질적 특성에 대한 논의는 소수에 불과하였다. 재난관리행정의 중요성을 강조하면서도 재난관리행정의 접근을 위한 이론적 논의나 체계적인 분석은 배제한 채 재난관리에 대한 재구조화에 대한 논의만 무성하였다. 이러한 논의들은 대부분 전통적 관료제적 접근을 전제로 하고 있다. 재난관리행정은 재난관리서비스의 특성과 재난 관리행정조직의 특성상 네트워크 거버넌스를 통한 연계성과 통합성의 실천으로 이해되어야 함에도 불구하고, 관료제적 위계의 방식으로 접근하는 오류를 범하고 있다. 본 논문에서는 재난관리행정의 특성에 대한 분석을 바탕으로 재난관리행정의 규범적 모델로서 네트워크 거버넌스(network governance)에 입각한 지역 거버넌스 모형의 적용가능성을 모색하였다. 먼저 네트워크를 전통적 서비스 공급방식인 시장 및 관료제와 비교하여 네트워크에서의 서비스 교환조건과 사회 메커니즘의 작용을 분석하였다. 이러한 분석을 토대로 재난관리서비스의 특성과 교환조건을 분석하고 우리나라에서 재난관리 네트워크 형성의 제약요인을 검토하였다. 마지막으로 극장의 논의를 기반으로 재난관리행정의 규범적 모델로서 네트워크 거버넌스적 설계방식을 제시하였다. The Disaster Management System(DMS) in Korea has been addressed in unessential and technical aspect, while the discussions on the essential attribute of it have been just a few. The importance of DMS has been highlighted, but the theoretical approach and systematic analysis on in has been excluded. The arguments only on the restructuring of DMS have prevailed. These arguments are usually based on the traditional bureaucratic approach that are very hierarchical. However, considering the characteristics of the organizations and services that compose DMS, it should be recognized as the practice of connectedness and integratedness through network governance, not as the hierarchical bureaucracy. Analyzing the attributes of DMS, this paper searches for the applicability of regional governance model grounded on the network governance as a normative model of DMS. Firstly, this research compares network with market and bureaucracy which are traditional way of service delivery, and analyzes the service exchange condition and operation of social mechanism on network. Secondly, it analyzes the characteristics and the exchange condition of disaster management service on the basis of analysis above, and reviews the factors that restricts the building up of disaster management network in Korea. Finally, it presents the network governance design as a normative model on the basis of the argument above.

BIPHASIC SYNTHESIS OF α-TETRALONE USING NICKEL COMPLEX CATALYSTS

Ahn, Wha Seung,Chung, Young Min,Lim, Phooi K . 한국화학공학회 1998 Korean Journal of Chemical Engineering Vol.15 No.5

Mathematical Model of a Monolith Catalytic Incinerator

Ahn, Wha Seung,Jang, Soo Hyun,Ha, Jae Mok,Park, Kwang Ja 한국화학공학회 1999 Korean Journal of Chemical Engineering Vol.16 No.6

A set of 1-dimensional mathematical models were developed to simulate both the steady state and transient performance of monolithic catalytic incinerators for VOC abatement. In modelling transient performance, quasi-steady state gas phase was assumed since transient response time is determined primarily by the thermal inertia of the monolith. Higher inlet gas temperatures and lower gas velocities were predicted to give higher conversion and faster response times. VOC concentration had little influence on the performance within the concentration ranges used. A catalytic incinerator is shown to operate typically under mass transfer limited conditions, and monolith channel density and shape have significant influence on the conversion and monolith heating time. The metallic monolith was predicted to show superior steady state and transient responses due to its lower thermal inertia generated by higher cell density and thinner wall.

Synthesis of mesoporous silica from bottom ash and its application for CO2 sorption

Wha-Seung Ahn,Chao Chen,Kwang-Seok You,Ji-Whan Ahn 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.3

A supernatant solution of silicate species extracted from bottom ash in a power plant was used to prepare a mesoporous silica by the synthesis protocol of SBA-15. XRD, N2 adsorption-desorption, and TEM confirmed a disordered mesopore structure. The pore volume and average pore size of the product were significantly larger than SBA-15 prepared using pure chemicals, and complementary textural mesoporosity was detected. When the mesoporous silica was tested for carbon dioxide sorption after polyethyleneimine (PEI) impregnation, substantially higher CO2 sorption capacity (169 mg CO2/g-sorbent) was achieved than that of PEI-impregnated pure SBA-15 under the same test conditions. High CO2 sorption capacity was maintained when the gas composition was changed to 15% CO2, and the hybrid material exhibited satisfactory performances during the 10 recycle runs.

Articles : A Study of Intramolecular Electron Exchange in Copper-Radical Complexes Involved in Catalysis Using ESR Spectroscopy

( Wha Seung Ahn ),( Ya Ping Zhong ),( Pooi K. Lim ) 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.5

ESR simulation and experimental results have been presented to show that transition metal-radical complexes can engage in intramolecular electron exchange and that the exchange gives rise to ESR asymmetric line broadening effect. Depending on the relative concentration of the redox-exchange pair, metal or radical-like spectrum can be obtained. Simulation results show that a metal-radical complex can be masked by its redox counterpart upto a relative concentration of 1 : 2 at a modest exchange rate of 3 x 10^8/s. Asymmetric line broadening was predicted to occur upon such metal-radical complexation. Experimentally, a pronounced ESR asymmetric line broadening was observed for Cu(Ⅱ) complexes of various redox-active ligands. Cu(Ⅱ) complex with redox-inert ammonia, however, showed no such evidence. Ligand displacement experiments established the reversibility of metalradical complexation and the associated ESR line broadening.

A STUDY OF INTRAMOLECULAR ELECTRON EXCHANGE IN COPPER - RADICAL COMPLEXES INVOLVED IN CATALYSIS USING ESR SPECTROSCOPY

Ahn, Wha Seung,Zhong, Yaping,Lim, Pooi K . 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.5

ESR simulation and experimental results have been presented to show that transition metal-radical complexes can engage in intramolecular electron exchange and that the exchange gives rise to ESR asymmetric line broadening effect. Depending on the relative concentration of the redox-exchange pair, metal or radical-like spectrum can be obtained. Simulation results show that a metal-radical complex can be masked by its redox counterpart upto a relative concentration of 1 : 2 at a modest exchange rate of 3 x 10^8/s. Asymmetric line broadening was predicted to occur upon such metal-radical complexation. Experimentally, a pronounced ESR asymmetric line broadening was observed for Cu(Ⅱ) complexes of various redox-active ligands. Cu(Ⅱ) complex with redox-inert ammonia, however, showed no such evidence. Ligand displacement experiments established the reversibility of metalradical complexation and the associated ESR line broadening.

총설 : 금속유기구조체를 이용한 이산화탄소 흡착 연구

안화승 ( Wha Seung Ahn ),김준 ( Jun Kim ),김희영 ( Hee Young Kim ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.2

금속유기구조체(metal-organic frameworks, MOF)는 넓은 비표면적, 규칙적인 구조 및 높게 분산된 금속 성분 등 뛰 어난 물리화학적 특성으로 인해 활발한 연구가 이뤄지고 있는 다공성 물질이며, 특히 가스의 흡착, 분리 매체로서 뛰 어난 성능이 보고되고 있다. MOF를 이용한 온실가스 이산화탄소의 흡착 연구는 상온 고압 영역에서 이산화탄소 저장 공정과 상온 저압 영역에서 이산화탄소 흡착 공정의 두 범주로 나눌 수 있으며, MOF의 넓은 비표면적 외에도 (1) MOF 의 빈 배위결합 자리, (2) MOF의 기능화, (3) MOF의 상호 침투 효과, 및 (4) 이온 교환 효과를 이용한 연구 결과가 보고되고 있다. MOF 물질들은 비교적 낮은 수분 및 열에 대한 안정성이 문제로 제기되고 있으며, 제올라이트 유사 구 조체(zeolitic imidazolate frameworks, ZIF) 또는 유기 골격 구조체(covalent organic frameworks, COF) 물질의 이산화 탄소 흡착 특성이 거론되고 있다. 본 소고에서는 MOF를 이용한 이산화탄소 흡착에 대한 최근의 연구 결과를 본 연구 실의 실험 결과를 중심으로 간략히 소개하고자 한다. Metal organic frameworks (MOFs) are a class of crystalline organic-inorganic hybrid compounds formed by coordination of metal clusters or ions with organic linkers. MOFs have recently attracted intense research interest due to their permanent porous structures, large surface areas and pore volume, high-dispersed metal species, and potential applications in gas adsorption, separation, and catalysis. CO2 adsorption in MOFs has been investigated in two areas of CO2 storage at high pressures and CO2 adsorption at atmospheric pressure conditions. In this short review, CO2 adsorption/ separation results using MOFs conducted in our laboratory was explained in terms of four contributing effects; (1) coordinatively unsaturated open metal sites, (2) functionalization, (3) interpenetration/catenation, and (4) ion-exchange. Zeolitic imidazolate frameworks (ZIFs) and covalent organic frameworks (COFs) were also considered as a candidate material.

기판 온도에 따른 La - Ca - Mn - O thin - film의 자기적 성질 연구

안근영(Geun Young Ahn),박승일(Seung Iel Park),이창우(Chang Woo Lee),김철성(Chul Sung Kim),이보화(Bo Wha Lee),이승화(Seung Wha Lee) 한국자기학회 2000 한국자기학회 학술연구발표회 논문개요집 Vol.10 No.1