http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Minwook Choi,Chunbiao Wu,Jae-Woong Kim 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.12
Aluminum is widely used in fields that require lightweight technology, such as in the aerospace and automobile industries. The welding of aluminum alloys, however, tends to generate large deformations in the welded structures due to its large heat conductivity and thermal expansion. Therefore, this study aims to reduce welding deformations that occur in the welding process by obtaining an optimal welding sequence. The welding sequence optimization process consists of two main stages. The first involves the prediction of the welding deformation behavior by using thermo-elastic-plastic finite element analysis. The second stage optimizes the welding sequence by using a genetic algorithm (GA), which can efficiently optimize very large solution spaces considering not only the welding sequence, but also the welding direction. In addition, this study proposed an appropriate and efficient GA for the present optimization problem. The optimization results showed that the developed finite element analysis model were in good agreement with the experimental results, and the proposed optimization tool can reduce the welding deformation considerably.
금속이온 잉크와 탄소나노튜브 용액의 에어브러싱 적층 기반 고성능 고내구성 박막형 히팅 모듈의 수월 제작 기술
김민욱(Minwook Kim),김민규(Mingyu Kim),김광준(Kwangjun Kim),박재원(Jaewon Park),이민영(Minyoung Lee),최현식(Hyunsik Choi),박종갑(Jonggab Park),노현찬(Hyeonchan Noh),윤부현(Boohyeon Youn),정은창(Eunchang Jeong),최광진(Kwangjin Choi),허 대한전기학회 2020 대한전기학회 학술대회 논문집 Vol.2020 No.7
최민욱(Choi Minwook) 한국옥외광고학회 2006 OOH광고학연구 Vol.3 No.2
본 논문은 문헌고찰을 중심으로 옥외광고 효과 분석에 관한 실무 현황과 학문적 연구 현황을 살펴봄으로써 옥외광고 효과 조사 및 연구의 전체 흐름을 이해하고 파악하는 한편, 이를 바탕으로 향후 조사 및 연구 방향을 탐색하였다. 특히 타 매체광고 효과 분석과의 비교 관점에서 옥외광고 효과 조사 및 연구의 현황을 분석하여 보았다. 분석결과 타 매체광고 효과 운석과 비교하여 옥외광고 효과 조사 및 연구는 광고물의 가시성(Visibility)을 중심으로 인지효과 측정을 중요시하는 경향을 보이고 있는 것으로 나타났다. 분석결과를 바탕으로 한 향후 조사 및 연구 방향으로 옥외광고의 태도와 행동효과에 대한 조사 및 연구의 활성화, 옥외광고 효과에 영향을 미치는 다양한 번인들에 대한 분석, 옥외광고 효과에 초점을 맞춘 이론과 연구방법의 정립, 유동인구, 교통량, 개별 옥외광고 장소 특성 등의 자료를 제공하는 시스템의 개발 및 활용, 다양한 종류의 옥외광고 미디어 효과에 대한 조사 및 연구를 제안하였다. This paper reviewed the articles about the effectiveness of outdoor advertising for the purpose of understanding the issues in this field and providing the guidelines for the future research in the basis of what was found. Especially, the articles were analyzed from the comparative point of view with the effectiveness of other media advertising. As a result of analysis, it was found that the evaluation of awareness by measuring the visibility of site was the main issue of the effectiveness study of outdoor advertising. Conclusively, the attitudinal and behavioral effect of outdoor advertising, the influence of various variables on the effectiveness of outdoor advertising, the theory and method for the effectiveness study of outdoor advertising, the development and application of circulation data system, and the effectiveness study for the various kinds of outdoor advertising were recommended for future research subjects.
Twist-Angle-Dependent Optoelectronics in a Few-Layer Transition-Metal Dichalcogenide Heterostructure
Choi, Woosuk,Akhtar, Imtisal,Rehman, Malik Abdul,Kim, Minwook,Kang, Dongwoon,Jung, Jongwan,Myung, Yoon,Kim, Jungcheol,Cheong, Hyeonsik,Seo, Yongho American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.2
<P>Lattice matching has been supposed to play an important role in the coupling between two materials in a vertical heterostructure (HS). To investigate this role, we fabricated a heterojunction device with a few layers of p-type WSe<SUB>2</SUB> and n-type MoSe<SUB>2</SUB> with different crystal orientation angles. The crystal orientations of WSe<SUB>2</SUB> and MoSe<SUB>2</SUB> were estimated using high-resolution X-ray diffraction. Heterojunction devices were fabricated with twist angles of 0, 15, and 30°. The <I>I</I>-<I>V</I> curve of the sample with the twist angle of 0° under the dark condition showed a diodelike behavior. The strong coupling due to lattice matching caused a well-established p-n junction. In cases of 15 and 30° samples, the van der Waals gap was built because of lattice mismatching, which resulted in the formation of a potential barrier. However, when the light-emitting diode light of 365 nm (3.4 eV) was illuminated, it was possible for excited electrons and holes to jump beyond the potential barrier and the current flowed well in both forward and reverse directions. The effects of the twist angle were analyzed by spectral responsivity and external quantum efficiency, where it was found that the untwisted HS exhibited higher sensitivity under IR illumination, whereas the twisting effect was not noticeable under UV illumination. From photoluminescence and Raman spectroscopy studies, it was confirmed that the twisted HS showed a weak coupling because of the lattice mismatch.</P> [FIG OMISSION]</BR>
Choi, Yu-Jin,Kim, Dae-Yoon,Park, Minwook,Yoon, Won-Jin,Lee, Yumin,Hwang, Joo-Kyoung,Chiang, Yeo-Wan,Kuo, Shiao-Wei,Hsu, Chih-Hao,Jeong, Kwang-Un American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.14
<P>The well-defined hierarchical superstructures constructed by the self assembly of programmed supramolecules can be organized for the fabrication of remote-controllable actuating and rewritable films. To realize this concept, we newly designed and synthesized a benzene-1,3,5-tricarboxamide (BTA) derivative (abbreviated as BTA-3AZO) containing photoresponsive azobenzene (AZO) mesogens on the periphery of the BTA core. BTA-3AZO was first self-assembled to nanocolumns mainly driven by the intermolecular hydrogen-bonds between BTA cores, and these self-assembled nanocolumns were further self-organized laterally to form the low-ordered hexagonal columnar liquid crystal (LC) phase below the isotropization temperature. Upon cooling, a lamello-columnar crystal phase emerged at room temperature via a highly ordered lamello-columnar LC phase. The three-dimensional (3D) organogel networks consisted of fibrous and lamellar superstructures were fabricated in the BTA-3AZO cyclohexane-methanol solutions. By tuning the wavelength of light, the shape and color of the 3D networked thin films were remote-controlled by the conformational changes of azobenzene moieties in the BTA-3AZO. The demonstrations of remote-controllable 3D actuating and rewritable films with the self-assembled hierarchical BTA-3AZO thin films can be stepping stones for the advanced flexible optoelectronic devices.</P>
Choi, Hyeongsu,Lee, Jeongsu,Shin, Seokyoon,Lee, Juhyun,Lee, Seungjin,Park, Hyunwoo,Kwon, Sejin,Lee, Namgue,Bang, Minwook,Lee, Seung-Beck,Jeon, Hyeongtag IOP Pub 2018 Nanotechnology Vol.29 No.21
<P>Representative tin sulfide compounds, tin monosulfide (SnS) and tin disulfide (SnS<SUB>2</SUB>) are strong candidates for future nanoelectronic devices, based on non-toxicity, low cost, unique structures and optoelectronic properties. However, it is insufficient for synthesizing of tin sulfide thin films using vapor phase deposition method which is capable of fabricating reproducible device and securing high quality films, and their device characteristics. In this study, we obtained highly crystalline SnS thin films by atomic layer deposition and obtained highly crystalline SnS<SUB>2</SUB> thin films by phase transition of the SnS thin films. The SnS thin film was transformed into SnS<SUB>2</SUB> thin film by annealing at 450 °C for 1 h in H<SUB>2</SUB>S atmosphere. This phase transition was confirmed by x-ray diffractometer and x-ray photoelectron spectroscopy, and we studied the cause of the phase transition. We then compared the film characteristics of these two tin sulfide thin films and their switching device characteristics. SnS and SnS<SUB>2</SUB> thin films had optical bandgaps of 1.35 and 2.70 eV, and absorption coefficients of about 10<SUP>5</SUP> and 10<SUP>4</SUP> cm<SUP>−1</SUP> in the visible region, respectively. In addition, SnS and SnS<SUB>2</SUB> thin films exhibited p-type and n-type semiconductor characteristics. In the images of high resolution-transmission electron microscopy, SnS and SnS<SUB>2</SUB> directly showed a highly crystalline orthorhombic and hexagonal layered structure. The field effect transistors of SnS and SnS<SUB>2</SUB> thin films exhibited on–off drain current ratios of 8.8 and 2.1 × 10<SUP>3</SUP> and mobilities of 0.21 and 0.014 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. This difference in switching device characteristics mainly depends on the carrier concentration because it contributes to off-state conductance and mobility. The major carrier concentrations of the SnS and SnS<SUB>2</SUB> thin films were 6.0?×?10<SUP>16</SUP> and 8.7?×?10<SUP>13</SUP> cm<SUP>−3</SUP>, respectively, in this experiment.</P>
Construction of light-responsive phase chirality from an achiral macrogelator
Choi, Yu-Jin,Yoon, Won-Jin,Park, Minwook,Kang, Dong-Gue,Bang, Geukcheon,Koo, Jahyeon,Lim, Seok-In,Park, Seohee,Jeong, Kwang-Un The Royal Society of Chemistry 2019 Journal of Materials Chemistry C Vol.7 No.11
<P>To realize light-responsive phase chirality from an achiral macrogelator in the solid state, a disc-shaped achiral macrogelator (B1AZ) was newly synthesized. B1AZ was self-assembled into a lamello-columnar structure in the bulk state, while single-handed helical fibrils (<I>H</I>F) with 400 nm of helical pitch were constructed by side-by-side lateral association of achiral B1AZ molecules in carvone chiral solvents. Even after the elimination of chiral solvents, the helical morphology and its chiroptical properties were precisely preserved. However, <I>H</I>F was not sensitive to UV light due to intense lateral packing. For remote-controlling the helical morphology, a single-helix (<I>H</I>S) with an 18 nm helical pitch was formed by utilizing <I>cis</I>-B1AZ sol. Upon irradiation with UV light, <I>H</I>S was transformed into spheroids (<I>S</I>) because of the <I>trans</I>-to-<I>cis</I> photo-isomerization of the azobenzene (AZ) of B1AZ. The photo-switchable phase chirality can be applied in light-responsive smart materials.</P>
Multilayer thin films for the construction of active repulsive hydrogen barriers
Park, Minwook,Kim, Dae-Yoon,Kang, Dong-Gue,Yoon, Won-Jin,Choi, Yu-Jin,Lee, Joong Hee,Jeong, Kwang-Un The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.6
<P>An active repulsive hydrogen (H2) barrier thin film (ARHB-tfilm) was fabricated by layer-by-layer (LbL), spin and plasma sequential coatings on a poly(ethylene terephthalate) (PET) film. Protons generated by the reduction of H2 on the palladium nanolayer can be trapped in the proton-rich Nafion region by the electrical repulsive force formed at the interface of the positively charged polymer nanolayer. The multilayer ARHB-tfilms showed a significant improvement in hydrogen gas barrier properties.</P>