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Fabrication of Various Conducting Polymers Using Graphene Oxide as a Chemical Oxidant
Kim, Minkyu,Lee, Choonghyeon,Seo, Young Deok,Cho, Sunghun,Kim, Jihoo,Lee, Gyeongseop,Kim, Yun Ki,Jang, Jyongsik American Chemical Society 2015 Chemistry of materials Vol.27 No.18
<P>Recently, using graphene oxide (GO) for “carbocatalysis” has been very attractive as a novel application of graphene-based nanomaterials and is expected to open a host of possibilities for chemical synthesis because of the abundance of natural carbon sources, as well as the low density, extensive chemical functionalization, hydrophilicity, low cost, and ease of preparation. Here, we demonstrate that the GO can play a role as a chemical oxidant for various CPs (polythiophene, polyaniline, and polypyrrole), and diverse graphene–CP composites (graphene–polythiophene, graphene–polyaniline, and graphene–polypyrrole) can simply and rapidly be synthesized by using the GO as both graphene precursor and chemical oxidant. The UV–vis analysis confirms that the GO has successfully polymerized the CPs and been transformed to reduced graphene oxide (RGO). The SEM and TEM analyses show that the CPs have successfully been coated on the few-layered graphene sheets. Raman analysis and series of FT-IR analyses have been conducted to survey what functional group in the GO polymerized the monomers, and they reveal that hydroxyl and epoxy groups in the GO polymerized the monomers. Finally, plausible polymerization mechanisms have specifically and deeply proposed based on the IR result, classical radical polymerization mechanisms of the CPs, and widely adopted thermal reduction mechanism of the GO.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-18/acs.chemmater.5b01408/production/images/medium/cm-2015-01408r_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b01408'>ACS Electronic Supporting Info</A></P>
Kim Yeji,Kim Jihoo,Kim Won June,Lee Eok Kyun,Choi Insung S. 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.5
3D graph convolutional network (3DGCN) is a graph neural network (GNN) variant that utilizes the 3D bond information on molecules for chemical tasks. In 3DGCN, the pooling operation extracts the molecular features from the atomic features for molecule embedding and dimensionality reduction. In this work, we investigated the pooling effects on the performance of 3DGCN in the classification of protein–ligand binding events, especially when a ligand is rotated with respect to a target protein in the 3D Cartesian coordinate. 3DGCN showed the general ability for recognizing the ligand rotation, and its prediction accuracy was found to be pooling-dependent. For example, 3DGCN with max pooling did not recognize the rotations of known active ligands for human β-secretase 1 faithfully, compared with the other pooling operations (sum, avg, and set2set). This work would contribute to augmented architecture evolution of 3DGCN for the chemical tasks that require the 3D molecular information including chirality.
Defect-Free Copolymer Gate Dielectrics for Gating MoS<sub>2</sub> Transistors
Kim, Min Je,Choi, Yongsuk,Seok, Jihoo,Lee, Sungjoo,Kim, Young Jun,Lee, Jun Young,Cho, Jeong Ho American Chemical Society 2018 The Journal of Physical Chemistry Part C Vol.122 No.23
<P>In this study, the poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane-<I>co</I>-cyclohexyl methacrylate) [p(V4D4-<I>co</I>-CHMA)] copolymer was developed for use as a gate dielectric in molybdenum disulfide (MoS<SUB>2</SUB>) field-effect transistors (FETs). The p(V4D4-<I>co</I>-CHMA) copolymer was synthesized via the initiated chemical vapor deposition (<I>i</I>CVD) of two types of monomers: 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA). Four vinyl groups of V4D4 monomers and cyclohexyl groups of CHMA monomers were introduced to enhance the electrical strength of gate dielectrics through the formation of a highly crosslinked network and to reduce the charge trap densities at the MoS<SUB>2</SUB>-dielectric interface, respectively. The <I>i</I>CVD-grown p(V4D4-<I>co</I>-CHMA) copolymer films yielded a dielectric constant of 2.3 and a leakage current of 3.8 × 10<SUP>-11</SUP> A/cm<SUP>2</SUP> at 1 MV/cm. The resulting MoS<SUB>2</SUB> FETs with p(V4D4-<I>co</I>-CHMA) gate dielectrics exhibited excellent electrical properties, including an electron mobility of 35.1 cm<SUP>2</SUP>/V s, a subthreshold swing of 0.2 V/dec, and an on-off current ratio of 2.6 × 10<SUP>6</SUP>. In addition, the environmental and operational stabilities of MoS<SUB>2</SUB> FETs with p(V4D4-<I>co</I>-CHMA) top-gate dielectrics were superior to those of devices with SiO<SUB>2</SUB> back-gate dielectrics. The use of <I>i</I>CVD-grown copolymer gate dielectrics as demonstrated in this study provides a novel approach to realizing next-generation two-dimensional electronics.</P> [FIG OMISSION]</BR>
Craftsmanship of Computer Based Digital Arts in Present and Future
Jihoo Kim,Sanghwa Hong 한국HCI학회 2023 한국HCI학회 학술대회 Vol.2023 No.2
With the advent of cryptocurrency, digital art is in the limelight with its inherently collectible medium. At the same time, craftsmanship is considered obsolete and less pursued in the art scene. But the concept of craftsmanship is worth reconsidering and redefined in the context of digital arts. NFT technology may protect the original artworks, but there still needs to be more standards in evaluating digital artistry. In this paper, we discuss a methodology to reconsider the value of craftsmanship in code-based digital art and reflect it as an evaluation element of contemporary art.
곰팡이 생육 및 곰팡이 독소 생산의 억제에 있어서의 유산균의 역할
김지후(Jihoo Kim),이희섭(Heeseob Lee) 한국생명과학회 2020 생명과학회지 Vol.30 No.12
최근 기후의 급속한 변화에 따라서 식품과 농산물에 Aspergillus, Fusarium 및 Penicillium속에 해당하는 곰팡이에 의한 오염이 빈번하고 이들에 의해 생성되는 aflatoxins, fumonisins, ochratoxins, patulin, trichothecenes, zearalenone등의 곰팡이 독소로 인해서 인간의 건강에 위해를 끼치고 또한 경제적인 손실을 가져오게 하고 있다. 최근 건강에 대한 소비자의 관심으로 인하여 기존에 사용되고 있는 프로피온산 및 소브산과 같은 보존료에 대한 거부감이 증가하고 있어 천연의 소재로부터 이를 대체할 만한 항진균제의 개발이 필요한 상황이다. 본 총설에서는 곰팡이의 생육 및 독소 생성을 제어하기 위한 생물학적 방법으로 유산균의 역할에 대하여 살펴보고자 하였다. 최근의 연구에 의하면 유산균은 저분자 화합물인 유기산, reuterin, 단백질 유래 화합물, 하이드록시 지방산, 페놀화합물과 같은 다양한 대사산물을 통하여 곰팡이의 생육을 효과적으로 억제시키고 있으며, 또한 유산균의 세포벽구성성분과의 흡착, 곰팡이 독소의 분해 및 곰팡이 독소의 생산 저해 등을 통하여 곰팡이 독소의 생산을 감소시키고 있는 사실이 제시되고 있다. 유산균은 다양한 종류를 포함하고 있으며 다양한 대사산물을 생산하고 있으므로 이를 바탕으로 효과적으로 곰팡이의 생육 및 독소 생산을 제어할 수 있는 잠재력 갖추고 있으므로, 유산균은 식품에 있어서 곰팡이의 생육을 조절하는 소재로서 주목 받을 것으로 기대된다. Over recent years, it has become evident that food and agricultural products are easily contaminated by fungi of Aspergillus, Fusarium, and Penicillium due to rapid climate change, which is not only a global food quality concern but also a serious health concern. Owing to consumers’ interest in health, resistance to preservatives such as propionic acid and sorbic acid (which have been used in the past) is increasing, so it is necessary to develop a substitute from natural materials. In this review, the role of lactic acid bacteria as a biological method for controlling the growth and toxin production of fungi was examined. According to recent studies, lactic acid bacteria effectively inhibit the growth of fungi through various metabolites such as organic acids with low molecular weight, reuterin, proteinaceous compounds, hydroxy fatty acids, and phenol compounds. Lactic acid bacteria effectively reduced mycotoxin production by fungi via adsorption of mycotoxin with lactic acid bacteria cell surface components, degradation of fungal mycotoxin, and inhibition of mycotoxin production. Lactic acid bacteria could be regarded as a potential anti-fungal and anti-mycotoxigenic material in the prevention of fungal contamination of food and agricultural products because lactic acid bacteria produce various kinds of potent metabolic compounds with anti-fungal activities.
다양성을 고려하는 사용자-시스템 상호작용 기반 추천 방법
김지후 ( Jihoo Kim ),채동규 ( Dong-kyu Chae ),김상욱 ( Sang-wook Kim ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2
추천 시스템은 사용자들의 과거 구매 이력 등을 학습해서 사용자들이 미래에 구매할 것 같은 상품을 추천한다. 대부분의 추천 시스템 관련 연구들은 사용자들과의 상호작용을 고려하지 않은 채 한 번의 모델 학습과 한 번의 추천만 수행하며, 사용자로부터 추천 결과에 대한 피드백을 받아서 더 나은 추천을 수행하려는 시도는 거의 이루어지지 않았다. 본 논문에서는 기존의 추천 모델들이 사용자와의 상호작용을 추가적으로 고려했을 때 어느 정도의 정확도 향상을 이룰 수 있는지에 대해서 분석한다. 특히 사용자와의 상호작용을 통해 사용자 취향의 다양성을 파악하고 이를 반영하여 더 나은 추천을 제공하는 방법에 대해서 논의한다.