Synthesis of Silver Nanowire Arrays by Thermal Decomposition of Silver Acetate

Seongeun Lee,오한준,이준희,이오연,지충수,정용수 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4

Rapid progress in nanotechnology has made it increasingly easier to nanostructure metal materials. This paper describes the formation of uniform silver nanowires by reducing silver acetate with PLLA polymer. The silver nanowires were prepared by wetting a porous template at 350 °C using 1.5 wt.% CH2Cl2 solution containing PLLA/silver acetate in a ratio of 1:1. A thermal analysis in the temperature range of 100 °C to 400 °C was carried out by a differential scanning calorimeter (DSC). An exothermic reaction peak associated with pure silver occurred at 352 °C at a heating rate of 5 °C/min. From the attenuated total reflectance (ATR) spectra analysis of the silver and PLLA composites, it was obtained that the absorption peak of the PLLA became weak by heating to successively higher temperatures in the range of 230 °C to 350 °C. The DSC and ATR results showed that the PLLA can be directly and easily removed at 350 °C, leaving the pure metal inside the pores. The silver nanowires consisted of nanoparticles whose average diameter was about 26.5 nm. And those nanowires with an aspect ratio of about 13 showed an UV-vis absorption peak, which is attributed to the surface plasmon excitation at 350 nm and 377 nm. Rapid progress in nanotechnology has made it increasingly easier to nanostructure metal materials. This paper describes the formation of uniform silver nanowires by reducing silver acetate with PLLA polymer. The silver nanowires were prepared by wetting a porous template at 350 °C using 1.5 wt.% CH2Cl2 solution containing PLLA/silver acetate in a ratio of 1:1. A thermal analysis in the temperature range of 100 °C to 400 °C was carried out by a differential scanning calorimeter (DSC). An exothermic reaction peak associated with pure silver occurred at 352 °C at a heating rate of 5 °C/min. From the attenuated total reflectance (ATR) spectra analysis of the silver and PLLA composites, it was obtained that the absorption peak of the PLLA became weak by heating to successively higher temperatures in the range of 230 °C to 350 °C. The DSC and ATR results showed that the PLLA can be directly and easily removed at 350 °C, leaving the pure metal inside the pores. The silver nanowires consisted of nanoparticles whose average diameter was about 26.5 nm. And those nanowires with an aspect ratio of about 13 showed an UV-vis absorption peak, which is attributed to the surface plasmon excitation at 350 nm and 377 nm.

Effects of Various Solution Wetting Conditions on the Morphology and the Crystallization of Poly (Vinylidene Fluoride) Nanotubes

Seongeun Lee,Byunggwan Lee,Jinwook Choi,정용수,오한준,지충수 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.3

Poly(vinylidene fluoride) nanotubes were fabricated by using solution wetting methods with nanoscale AAO templates whose pore diameters were about 90 nm and 190 nm when prepared by anodizing in oxalic-/and phosphoric-acid solutions, respectively. Wetting of the AAO template was done under two conditions of heat treatments, annealing at 200℃ and then cooling to 130℃ and annealing for 1 h at 130℃ after having been kept at room temperatures. The synthesis of nanowires and nantubes was particularly affected by the annealing condition. The attenuated total reflectance (ATR) spectroscopy result suggested that the PVDF nanotubes crystallized exclusively in the α form while the nanowires formed in a mixture of α and γ phases. These results indicate that the morphology and the crystallization of the PVDF nanostructures are affected by the annealing time and temperature and by the solution wetting conditions. X-ray diffraction (XRD) patterns with a relatively high intensity at the (020) plane showed that a texture is induced in α-PVDF nanotubes when a wetting solution of 10 wt% PVDF in DMF is used.

중학교의 학업성취도에 대한 지역교육청 효과 분석

이성은 ( Seongeun Lee ) 경북대학교 중등교육연구소 2015 중등교육연구 Vol.63 No.2

이 연구는 단위학교 지원이라는 지역교육청의 역할을 교육행정기관의 교육책무성 관점에서 보고, 성과 중심 책무성에 기반하여 중학교 학업성취도에 대한 지역교육청 효과 탐색을 목적으로 하였다. 국가수준학업성취도평가 자료와 학교정보공시 및 교육통계자료를 활용하였으며, 학교 수준과 지역교육청 수준의 2수준 다층모형을 적용하여 분석하였다. 연구결과 지역교육청 간 학업성취도의 차이가 있으며, 지역교육청의 학교 교육력 제고를 위한 학교지원기능에 기반 한 책무성 측면에서 어떠한 특성들이 학력차이를 만드는지 탐색해보아야 할 타당성을 제공하였다. 또한 학교지원기능을 극대화하기 위해 지역교육청의 관리, 감독 대상 학교 수 및 학교규모 면에서 지역교육청이 적정규모로 운영되어야 함을 보여주었다. 그리고 중학교의 경우 지역교육청 수준에서 학생 1인당 방과후학교지원비가 학업성취도에 영향을 미치는 것으로 나타나 교육소외계층에 대한 지원과 다양한 교육기회의 제공 위한 정책적 노력이 중요함을 시사하고 있다. In this paper, the roles of district offices of education are defined as support the unit school based on educational accountability of an education-administration-agency. The purpose of this study is to seek factors which influence on academic achievement in the level of district offices of education. This study was analyzed with a multilevel model to seek determinants influencing on academic achievement of 180 district offices of education in primary education. The conclusions of this study are as follows. First, there was the difference of academic achievement between district offices of education. And it provides the validity to investigate which characteristics of district offices of education made the gap of academic achievement. Second, the result was showed that one district office of education has suitable scale of schools to supervise and support efficiently in order to improve educational power. Third, the financial support for the after-school in the level of district offices of education was influence on academic achievement positively. It means that policy efforts to support and to provide a variety of education opportunities are important.

감시 영역 적응형 이중 신경망 기반 군중 밀집도 모니터링 시스템

이성은(Lee, Seongeun),이소은(Lee, Soeun),최해철(Choi, Haechul) 한국방송·미디어공학회 2023 한국방송공학회 학술발표대회 논문집 Vol.2023 No.11

다문화가정의 삶의 질 향상을 위한 다문화지원 서비스 정책 발전 방안 연구

이성은(Seongeun Lee),최경철(Kyungchul Choi) 인문사회과학기술융합학회 2019 예술인문사회융합멀티미디어논문지 Vol.9 No.5

본 연구는 급변하고 있는 사회적인 변화 중 가장 많은 부분을 차지하고 있는 다문화가족에 대한 현황을 알아보고, 현재 운영되고 있는 다문화 가정을 대상으로 하는 다문화지원 서비스에 대한 사례를 살펴본다. 이를 통해 다문화가정을 대상으로 하는 서비스 과정 및 진행에 대한 문제점을 도출하여, 향후 다문화가정을 대상으로 하는 다문화지원 서비스 개선방안을 마련하여, 다문화가정의 실질적 지원이 되는 복지서비스 체계 마련 및 실효성 있는 복지정책수립에 도움이 되고자 하는데 목적이 있다한국사회가 다문화사회로 진입하면서 겪은 시행착오를 통해 얻은 많은 발전 속에서, 현재의 다문화 지원정책 서비스를 들여다보면, 서비스 형태 및 방법적인 부분 및 전달과정에 대한 다양한 문제점들이 도출되고 있기 때문에, 결과주의적 관점이 아닌, 과정주의적 관점으로서의 다문화가정 지원 서비스 체계의 개선이 무엇보다 시급하다. 이를 위한 본 연구의 내용은 다음과 같다. 첫째, 국내의 다문화 사회의 형성과정을 바탕으로, 현재 국내에서 지원하고 있는 다문화가정 정책을 분석함으로써, 이에 따른 문제를 파악하고, 개선방안을 모색한다. 이를 통해, 다문화 가정에 대한 정책지원 현황을 살펴본다. 셋째, 실효성 있는 정책 반영정도를 알아보기 위해, 국내에 거주하고 있는 다문화 가족을 대상으로 인터뷰를 실시하고, 이를 분석하여 현재 다문화 지원서비스의 개선방안을 제시한다. 넷째, 국내의 다문화 정책을 기반으로 한 다문화 서비스 제도에 대한 대안을 마련하고, 새로운 방법의 정책을 제안하여 한국사회가 진정한 다문화사회로 발전할 수 있는 방법을 모색해하고자 한다. This study examines the current status of multicultural families, which are the most common social changes in the rapidly changing world, and examines the cases of multicultural support services for multicultural families currently in operation. Through this process, problems of service process and progress for multicultural families will be elucidated. In the future, multicultural support services for multicultural families will be improved, and a welfare service system will be provided to support multicultural families. It is aimed at helping policy formulation. In view of the many developments gained through the trial and error of Korean society as it entered into the multicultural society, various problems of service type, methodical part, and delivery process are derived from the current multicultural support policy service, It is urgent to improve the multicultural home support service system as a process-oriented view rather than a viewpoint. The contents of this study are as follows. First, based on the process of forming a multicultural society in Korea, we analyze the policies of multicultural families supported in Korea and identify the problems and seek ways to improve them. Through this, we will examine the status of policy support for multicultural families. Third, in order to examine the degree of effective policy reflection, interviews are conducted for multicultural families residing in Korea, and analysis of them is presented to suggest ways to improve multicultural support services. Fourth, we plan to find alternatives to the multicultural service system based on the domestic multicultural policy, and propose a new policy to find ways for the Korean society to develop into a truly multicultural society.

다양한 수위조건에서의 300kHz 초음파 캐비테이션 산화반응 연구

이성은(Seongeun Lee),나이슬(Iseul Na),손영규(Younggyu Son) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11

3-Way 록업클러치가 적용된 토크컨버터의 내부 Oil Path 구조에 따른 클러치 작동 응답성에 관한 연구

이성은(Seongeun Lee),안효재(Hyojae An) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11

300㎑ 초음파 산화 반응기에서의 수위 및 용존가스 영향 연구

이성은(Seongeun Lee),손영규(Younggyu Son),나이슬(Iseul Na) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11

토크 컨버터 비틀림 진동 특성에 대한 연구

이성은(SeongEun Lee),최완(Wan Choi),장재덕(JaeDuk Jang),주인식(InSik Joo) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

Recently, in order to improve the fuel economy in vehicle, it has been tried to lower torque converter lock-up speed in automatic transmission. But this trend is likely to cause the abnormal vibration and surge accompanied by the vehicle vibration during a drive. The torsional vibration characteristics by many researchers were investigated on the NVH issues. but so far to comprehend the vibration characteristics of the vehicle power train system has so difficulty doing. So, the torsional vibration analysis of the vehicle is investigated by the vehicle power train modeling using AMESim<SUP>®</SUP> that is a commonly used program for analyzing vehicle dynamics characteristics. The vehicle power train model shows the torque fluctuation of vehicle caused by changing torque converter’s primary inertia, secondary inertia, stiffness and hysteresis of damper. Additionally, this paper presents a guideline for the torque converter design to minimize the torsional vibration in power train of automatic transmission vehicle.

토크 컨버터 댐퍼 시스템 다단화를 통한 진동특성 최적화

이성은(Seongeun Lee),최완(Wan Choi),장재덕(Jaeduk Jang),주인식(Insik Joo) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

Recently, in order to improve the fuel economy in vehicle, it has been tried to lower torque converter lock-up speed and the vehicle’ engine is composed of direct injection, variable compression ratio, variable engine displacement, cylinder deactivation, homogeneous charge compression ignition, turbo charger and high pressure fuel injection. Accordingly, this trend is likely to cause the abnormal vibration accompanied by the vehicle vibration. To overcome disadvantageous vibration characteristic , Several type of advance damper system have been developed and the existing damper system have been optimized with the multi-stage damper system. The torsional vibration in the research is analyzed by the vehicle power train model using AMESim that is a commonly used program for analyzing vehicle dynamic characteristics. In this research, it is focused on developing that the vehicle vibration characteristic is optimized by the damper system with the multi-stage.