Fe3O4–ZnO Core–Shell Nanoparticles Fabricated by Ultra-Thin Atomic Layer Deposition Technique as a Drug Delivery Vehicle

Sejong Seong,In‑Sung Park,Yong Chan Jung,Taehoon Lee,Seon Yong Kim,Su‑Jae Lee,Jin-HoAhn 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.4

Fe3O4–ZnO nanoparticles with core–shell structures were successfully fabricated by an atomic layer deposition method. The core–shell NPs consisted of superparamagnetic Fe3O4cores of 100 nm average size and conformal ZnO shells of 10 nmthickness. The NPs showed a saturation magnetization of ~ 23 emu/g, which is suitable for magnetic delivery of the particles. Cytotoxicity testing revealed that the Fe3O4–ZnO NPs have high cell viability (over 90%) after 24 h culture. Also, theyexhibited a high ibuprofen-loading capacity (640 μg per mg of the particles) and good release ability (> 90% after 72 h insimulated body fluid). As a result, the Fe3O4–ZnO nanoparticles with conformal ultra-thin ZnO shell layers are anticipatedas promising drug delivery vehicles with acceptable cell viability and high drug loading-release abilities.

Fabrication of Fe₃O₄-ZnO core-shell nanoparticles by rotational atomic layer deposition and their multi-functional properties

Seong, Sejong,Jung, Yong Chan,Lee, Taehoon,Park, In-Sung,Ahn, Jinho Elsevier 2016 CURRENT APPLIED PHYSICS Vol.16 No.12

<P>Fe3O4-ZnO core-shell nanoparticles (NPs) were fabricated using a flow-type atomic layer deposition (ALD) apparatus, equipped with a rotational reactor. This overcomes problems with aggregated NP cores that are commonly encountered when fabricating core-shell NPs by conventional ALD. The composition, crystallographic, optical, and magnetic properties of the NPs were investigated for multifunctional applications. Diethylzinc and deionized water were used as the metal precursor and oxidant, respectively, for preparing the ZnO shells by ALD. The ALD process used in this study differed from conventional ALD processes, in that it included extra evacuation and reaction steps for coating NP cores with shells. The evacuation and reaction processes allowed the precursor and reactant to sufficiently react with the large surface area NPs. The thickness of the shell was controlled by varying the ALD cycle parameters. The morphology and crystallinity of the ZnO shells were investigated by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping. The X-ray powder diffraction pattern of the Fe3O4-ZnO NPs indicated the formation of ZnO shells of wurtzite structure on the Fe3O4 cores. The stoichiometry of the ZnO shells was analyzed by X-ray photoelectron spectroscopy. Photoluminescence and magnetization measurements of the Fe3O4-ZnO NPs showed that they simultaneously exhibited photoluminescence from ZnO and superparamagnetism from Fe3O4. (C) 2016 Elsevier B.V. All rights reserved.</P>

Enhanced uniformity in electrical and optical properties of ITO thin films using a wide thermal annealing system

Seong, Sejong,Jung, Yong Chan,Lee, Taehoon,Park, In-Sung,Ahn, Jinho Elsevier 2018 Materials science in semiconductor processing Vol.79 No.-

<P>We investigated the effects of thermal treatment using a wide thermal annealing (w-TA) system on the structural, electrical, and optical properties of indium tin oxide (ITO) thin films deposited by radio-frequency magnetron sputtering at room temperature. The w-TA system was designed to enhance the uniformities of the electrical and optical properties of thin films in a large-scale 8G display substrate. The ITO films were annealed at 350 degrees C and 450 degrees C in a planar w-TA chamber. The X-ray diffraction analysis showed crystallization of ITO films along the <111> direction after the annealing process and an increase in their crystallite size with process temperature. The uniform characteristics of the electrical resistance and optical transmittance of ITO films are suitable for wide transparent electrodes, being the major advantage of the w-TA system. The sheet resistance (Rs) of the ITO thin films was lower, down to 18 Omega/square, and the variation of the Rs value was also narrowed down, which is measured by Rs at diverse points, after the w-TA process. The carrier concentration and mobility of the ITO films improved with an increase in annealing temperatures. The annealed ITO films exhibited both improved transmittance and better uniformity in the visible light region on a large 8G substrate. The band gap energy and carrier concentration of the ITO films increased after thermal annealing, as suggested by both the blue shift of the refractive index and the extinction coefficient values.</P>

Analysis of Airtightness and Air Leakage of Wooden Houses in Korea

Sejong Kim,Yoon-seong Chang,Joo-saeng Park,Kug-bo Shim 한국목재공학회 2017 목재공학 Vol.45 No.6

Airtightness of buildings is one of critical aspects of its energy performance. To build up references of air-tightness of wooden houses built in Korea, blower door tests have been carried out in 42 houses since 2006. Causes of air leakage were investigated recently. The average value of air change rate was 3.7 h^-1 for light frame house and 5.5 h^-1 for post-beam construction at ACH50 (air change per hour at 50 Pa air pressure differ-ence). Foam type insulation was more advantageous in ensuring building airtightness than glass fiber batt. Airtightness of wooden houses which were constructed after 2010 was improved to have less than 1.5 h^-1 of ACH50, threshold for application of artificial air change. The average air change rate of CLT (cross laminated timber) houses showed the lowest value, 1.1 h^-1, among the tested structures.

Quantification of Carbon Reduction Effects of Domestic Wood Products for Valuation of Public Benefit

( Yoon-seong Chang ),( Sejong Kim ),( Kwang-mo Kim ),( Hwanmyeong Yeo ),( Kug-bo Shim ) 한국목재공학회 2018 목재공학 Vol.46 No.2

This study was carried out to quantify degree of contribution of harvested wood product (HWP) on mitigation of climate change by valuation of public benefits, environmentally and economically. The potential carbon dioxide emission reduction of HWP was estimated by accounting carbon storage effect and substitution effect. Based on 2014 statistics of Korea Forest Service, domestic HWPs were sorted by two categories, such as wood products produced domestically from domestic and imported roundwood. The wood products were divided into seven items; sawnwood, plywood, particle board, fiberboard (MDF), paper (including pulp), biomass (wood pellet) and other products. The carbon stock of wood products and substitution effects during manufacturing process was evaluated by items. Based on the relevant carbon emission factor and life cycle analysis, the amount of carbon dioxide emission per unit volume on HWP was quantified. The amounts of carbon stock of HWP produced from domestic and from imported roundwood were 3.8 million tCO_2eq., and 2.6 million tCO_2eq., respectively. Also, each reduction of carbon emission by substitution effect of HWP produced from domestic and imported roundwood was 3.1 million tCO_2eq. and 2.1 million tCO_2eq., respectively. The results of this study, the amount of carbon emission reduction of HWP, can be effectively used as a basic data for promotion of wood utilization to revise and establish new wood utilization promotion policy such as ‘forest carbon offset scheme’, and ‘carbon storage labeling system of HWP’.

장식조명 빛공해 개선방안 도출을 위한 실태조사 항목 구성방식 제안

유성식(Seong-sik Yoo),이세종(Sejong Lee),전순호(Sunho Jeon),김훈(Hoon Kim) 한국조명·전기설비학회 2014 한국조명·전기설비학회 학술대회논문집 Vol.2014 No.11

레이저 초음파를 이용한 Ti-6Al-4V/YSZ 3D 프린팅 부품의 인장특성 평가

강세종(Sejong Ghang),박성현(Seong-Hyun Park),유지웅(Jiung Yoo),장경영(Kyung-Young Jhang) 한국비파괴검사학회 2022 한국비파괴검사학회 춘계학술대회 초록집 Vol.2022 No.5

축소모형 실험을 통한 벽체의 열관류 측정

장윤성 ( Yoon Seong Chang ),김세종 ( Sejong Kim ),심국보 ( Kug Bo Shim ),이상준 ( Sang Joon Lee ),한연중 ( Yeonjung Han ),박용건 ( Yonggun Park ),여환명 ( Hwanmyeong Yeo ) 한국목재공학회 2015 목재공학 Vol.43 No.6

구조용 부재의 단열성능에 대한 적절한 평가와 냉난방에너지에 대한 합리적 제어는 건물의 에너지효율을 향상시키기 위하여 매우 중요하다. 한국의 일반적인 주택 난방방식은 바닥난방이다. 이와 같은 복사난방방식은 국내의 지정학적인 조건 또는 기후에 적합할 뿐만 아니라 온열감에 따른 정서적 안정감을 준다는 장점을 가진다. 국내의 바닥난방시스템을 적용하여, 목조공간과 콘크리트조 공간을 대상으로 축소모형을 제작하였다. 천장은 스티로폼으로 단열하고 벽과 바닥은 각각 합판과 콘크리트로 구성하였다. 바닥에는 난방필름을 부착하였다. 바닥난방에 따른 실내의 온도분포는 열전대로 측정하였고, 벽체 표면의 온도는 적외선 열화상 카메라로 측정하였다. 목조주택의 에너지효율 향상을 위한 데이터베이스 구축을 위해 축소모형의 단열성능을 평가하였다. 다양한 벽체와 바닥구성을 지닌 모형들의 단열성능평가 자료는 실제 주택의 열환경 분석시 참고기준으로 이용될 수 있을 것으로 기대된다. Appropriate evaluation of thermal insulation property of structural member and valid control of cooling/heating energy are important for improving building’s energy efficiency. The typical heating system of house in Korea is the floor heating one. The radiation heating system is not only appropriate to climate and geographic conditions of Korea, but also advantageous to provide emotional comfort by the warm feeling of floor. Based on living conditions in Korea, scaled models of the wooden house and concrete house were designed. The ceiling was made of styrofoam insulation and the four sided walls and bottom were made of plywood and concrete, respectively. The floor was heated by heating film. Indoor vertical temperature distributions by floor heating system were measured by thermocouple, and surface temperatures on walls were measured by infrared thermography. Also, thermal insulation property of wooden wall was evaluated to build database for improving energy efficiency of wooden building. It is expected that collected data during tests of various types of floor and wall composition could be referenced for evaluating thermal environment of actual conditions of houses.

국산 참나무류의 이용활성화를 위한 건조특성 및 가공수율 평가

장윤성 ( Yoon-seong Chang ),신현경 ( Hyun-kyeong Shin ),김세종 ( Sejong Kim ),한연중 ( Yeonjung Han ),김민지 ( Min-ji Kim ),엄창득 ( Chang-deuk Eom ),이영근 ( Young-geun Lee ),심국보 ( Kug-bo Shim ) 한국목재공학회 2017 목재공학 Vol.45 No.5

본 연구에서는 국산 참나무류의 고부가가치재 이용기술 개발을 위해 굴참나무와 신갈나무를 대상으로 입목으로부터 마루판재까지의 가공수율을 조사하였다. 또한 참나무류 건조시간 단축을 위한 건조스케줄의 개선 및 물성평가를 수행하였다. 건조시간은 총 173시간이 소요되었으며, 최종함수율은 굴참나무 5.39%, 신갈나무 4.17%로 측정되었다. 건조에 따른 굴참나무와 신갈나무의 재색변화는 ΔE 값이 7∼11으로 현저한 변화를 보였다. 건조에 따른 수축률은 굴참나무의 경우, 접선방향 8.1%, 방사방향 5.0%이었으며, 신갈나무의 경우, 접선방향 8.5%, 방사방향 6.2%로 평가되었다. 제재수율은 30∼40%, 최종제품수율은 8∼15%로 평가되었다. 본 연구에서 조사된 참나무류의 가공특성은 아직까지 저이용되고 있는 국산 활엽수의 효율적인 생산계획을 수립하는데 기여할 수 있을 것으로 기대된다. In order to develop value-added utilization technology of domestic oaks the processing yield rate from the standing tree to the flooring material for the Quercus variabilis and Quercus mongolica were investigated. Also, to reduce drying time, improved drying schedule was applied and the physical properties were measured. The drying time was 173 hours in total, and the final moisture content was 5.39% (Quercus variabilis) and 4.17% (Quercus mongolica). The color difference of oak lumber before and after drying showed a significant change as ΔE value from 7 to 11. The shrinkage rates of Quercus variabilis and Quercus mongolica during drying were 8.1% and 8.5% in the tangential direction and 5.0% and 6.2% in the radial direction, respectively. The lumber manufacturing yield rate of sawn lumber was 30 to 40% and that of the final product was 8 to 15%. It is expected that the processing characteristics of the Quercus species investigated in this research could contribute to formulate an efficient production plan of domestic hardwoods that are still under utilization.

목조주택 온실가스 배출량 평가를 위한 간이 전과정평가 툴 개발

장윤성 ( Yoon-seong Chang ),김세종 ( Sejong Kim ),손휘림 ( Whi-lim Son ),정순철 ( Soon-chul Jung ),신현경 ( Hyun-kyeong Shin ),심국보 ( Kug-bo Shim ) 한국목재공학회 2017 목재공학 Vol.45 No.5

본 연구에서는 목조건축 전과정평가의 접근성과 활용성을 높이고자 간이 전과정평가 툴(simplified LCA)을 개발하고 이를 검증하기 위하여 전과정평가(LCA) 상용프로그램(Simapro.7)과의 비교를 수행하였다. 전과정목록을 바탕으로 환경영향을 평가한 결과, 대상 목조주택 1동의 전과정평가 결과와 간이 전과정평가 툴의 결과는 약 1% 정도로 나타났다. 따라서, 간이 전과정평가 툴을 통한 목조건축의 온실가스 배출량 분석이 가능할 것으로 판단되며, 사용자 편의를 기반으로 사례추가를 통한 국내 목조건축 환경영향 데이터베이스 구축에 이용될 수 있을 것으로 생각된다. 또한 목조건축 건설에 따른 온실가스 저감효과는 시공단계까지 온실가스 배출량의 약 53%를 상쇄하는 효과를 가지는 것으로 평가되었다. 본 연구결과는 목조주택의 친환경적 이미지 제고를 통한 목조주택 보급확대 정책을 지원할 수 있는 근거로써 임업분야 신기후체제 대응에 기여할 수 있을 것으로 기대된다. In this study, simplified LCA (life cycle assessment) tool was developed to increase accessibility and availability on LCA timber construction. The result of simplified LCA was compared with commercial program on LCA (Simapro.7) to verify its availability. As a result of evaluating environmental impacts with the Life Cycle Inventory of all processes, gap between LCA and simplified LCA tools of timber construction was about 1%. Therefore, the simplified LCA tool could analyse greenhouse gas emissions of timber construction and to expand number of data set through improved conveniency of users for developing database of timber construction in Korea. The reduction effects of greenhouse gas emissions of timber construction was about 53% of total emission offset up to construction phase. The results of this study would support decision making process to expand to timber construction policy to showcase environmental friendliness of timber construction. It was expected to contribute to response to the New climate regime in forestry.