Synthesis and Characterization of Diketopyrrolopyrrole Derivatives as Organic Semiconductors for Organic Thin-Film Transistors

Kim, Hyekyoung,Van, Nguyen Pham Thanh,Kim, Choongik,Seo, SungYong American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.6

<P>New diketopyrrolopyrrole derivatives end-functionalizaed with phenyl acetylene, 2,5-bis(2-ethylhexyl)-3,6-bis(5-(phenylethynyl)thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (1) and 2,5-bis(2-ethylhexyl)-3,6-bis(5-((4-(trifluoromethyl)phenyl)ethynyl)thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (2), were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Compound 1 exhibited p-channel characteristics with carrier mobility as high as 10(-3) cm(2)/Vs and a current on/off ratio > 10(5) for top-contact/bottom-gate OTFT devices.</P>

Recent Advance of Flexible Organic Memory Device

Kim, Jaeyong,Hung, Tran Quang,Kim, Choongik The Institute of Semiconductor Engineers 2020 Journal of semiconductor engineering Vol.1 No.1

With the recent emergence of foldable electronic devices, interest in flexible organic memory is significantly growing. There are three types of flexible organic memory that have been researched so far: floating-gate (FG) memory, ferroelectric field-effect-transistor (FeFET) memory, and resistive memory. Herein, performance parameters and operation mechanisms of each type of memory device are introduced, along with a brief summarization of recent research progress in flexible organic memory.

Towards Sustainable Environmental Policy and Management in the Fourth Industrial Revolution: Evidence from Big Data Analytics

Choongik CHOI,Chunil KIM,Chulmin KIM 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.3

This study is to explore the relationship between the Fourth Industrial Revolution and the environment using the big data methodology. We scrutinize the trend of the Fourth Industrial revolution, in association with the environment, and provide implications for a more desirable future environmental policy. The results show that the Industrial Revolution has been generally perceived as negative to environment before the 2010s, while it has been widely regarded as positive after the period. It is highly expected that the Fourth Industrial Revolution will be capable of functioning as a new alternative to enhance the quality of the biophysical and social environment. This study justifies that the new wave of technological development may serve as a cure for the enhancement of the environmental quality. The positive linkage between the new technological development and the environment from this study clearly indicates that the environmental industry and environmental technologies will be key economic factors in the next-generation society. They should be of critical importance in shaping our cities into clearer and greener spaces, and people will continuously depend on the development of new environmental technologies in order to correct environmental damages.

Polyurethane triblock copolymer gate dielectrics for low-voltage organic thin-film transistors

Kim, Dongkyu,Kim, Choongik,Earmme, Taeshik Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-

<P><B>Abstract</B></P> <P>Novel polyurethane triblock copolymers comprising polycaprolactone diol (PCL), 1,6-hexamethylene diisocyanate (HMDI), and polyethylene glycol (PEG) were synthesized for use as gate dielectric for organic thin-film transistors (OTFTs). Thin films of polyurethane gate dielectrics processed from solution exhibit excellent insulating properties (∼7×10<SUP>−7</SUP> A/cm<SUP>2</SUP> at 1V) as well as large areal capacitance (170nF/cm<SUP>2</SUP>) with film thickness of ∼50nm. OTFTs are fabricated with representative n-channel organic semiconductor (N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide; PTCDI-C13) using the developed gate dielectrics, and the resulting devices show decent electrical performance with negligible hysteresis at low operating voltage of 1V.</P>

Effect of methane–sugar interaction on the solubility of methane in an aqueous solution

Kim, Kwangmin,Kwon, Taejin,Sung, Bong June,Kim, Choongik Academic Press 2017 Journal of Colloid and Interface Science Vol. No.

<P><B>Abstract</B></P> <P>In this study, the effect of methane–sugar interaction on the solubility of methane in an aqueous solution at ambient pressure was investigated. Various sugars, such as fructose, glucose, sucrose, maltose, and raffinose, were used, and depending on the type and concentration of sugar, the methane solubility increased from 21.72mg/L (in pure water) to 24.86mg/L. Sugars with a low hydrogen-bonding number between the water and sugar molecules exhibited a large enhancement in methane solubility. The solute partitioning model and molecular dynamics simulations were employed to verify the results obtained for the experimental solubility of methane in aqueous sugar solutions.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

부동산 보유세의 역진성과 전세가 귀착효과

최충익 ( Choi Choongik ),김철민 ( Kim Chulmin ),이동관 ( Lee Dongkwan ),김천일 ( Kim Chunil ) 한국감정평가학회 2020 감정평가학논집 Vol.19 No.3

본 논문은 부동산 보유세의 역진성과 전세가 귀착효과를 파악하기 위해 실증분석하고 있다. 보유세 개편을 두고 다양한 논의들이 이루어졌지만 부동산 보유세가 주택보유자에게 경제적으로 얼마나 부담이 되는지에 대한 담론과 보유세가 상승할 경우 이를 세입자에게 전가시킬 것인지에 대한 실증적 논의는 제대로 이루어지지 못했다. 이에 본 논문에서는 주택 보유자의 사회경제적 특성 파악을 토대로 부동산 보유세의 역진성 및 전세가 귀착효과에 대한 실증분석을 하고 있다. 분석자료로 주택소유자 개별특성을 파악할 수 있는 마이크로 데이터를 사용하여 실제 주택보유자의 특징을 분석하고 서울시 전세 실거래가를 토대로 부동산 보유세의 전세가 귀착효과를 분석하였다. 분석결과 소득계층별 보유세 부담의 역진성은 뚜렷하게 나타났다. 재정패널자료를 통해 주택보유가구의 보유세 부담을 소득수준별에 따라 분석한 결과 가구소득 1분위부터 4분위까지 소득계층별 세부담의 역진성이 발견되었다. 또한 종합부동산세 대상 아파트가 종합부동세 납부 대상이 아닌 아파트에 비해 전세가격이 높지 않게 나타났으며, 종부세 부과에 따른 전세금 전가효과는 분석결과 나타나지 않았다. 이는 전가시킬 만큼의 충분한 종합부동산세가 부과되지 않았기 때문일 수 있으며, 종부세가 충분히 증가할 경우 전세금으로의 전가효과는 다른 결과를 나타낼 수 있음을 시사한다. This paper conducted empirical analyses in order to explore the incidence effect of real estate tax on the Jeonse costs and the regression of the property tax. Recently, various discussions have been made over the reformulation of property tax, but the discourse on how much the tax is economically burdened to homeowners and whether the increase in the tax will be passed onto tenants has not been properly investigated. The purpose of this study is two fold. First, we analyzed the real estate tax burden by income class using the Public Finance Panel Survey data. Finally, we explored the possibility of the incidence of real estate tax on the Jeonse tenants by employing a simple quasi-experimental design. We found the Jeonse prices for the apartments, which are subject to the comprehensive real estate tax, are not higher than those for the apartments, which are not subject to the comprehensive tax. This indicates that (1) there is no evidence on the incidence of the tax on the Jeonse tenants, and (2) the amount of tax levied is not enough to trigger the incidence. We expect that the pattern of the incidence would turn to the different direction if the tax rates rise.

Enhanced mass transfer rate of methane in aqueous phase via methyl-functionalized SBA-15

Lee, Jaewon,Kim, Kwangmin,Chang, In Seop,Kim, Myung-Gil,Ha, Kyoung-Su,Lee, Eun Yeol,Lee, Jinwon,Kim, Choongik Elsevier 2016 Journal of molecular liquids Vol.215 No.-

<P><B>Abstract</B></P> <P>Methyl-functionalized mesoporous silica SBA-15, synthesized from tetraethyl-orthosilicate (TEOS) and methyltriethoxysilane (MTES), were employed as additives for the enhancement of volumetric mass transfer coefficient (<I>k</I> <SUB>L</SUB> <I>a</I>) of methane in aqueous solution. The surface functional group, highly ordered structure, and exceptionally high surface area exerted great influence on mass transfer rate of methane in aqueous solution. Especially, the fraction of surface functional groups controlled by adjusting the ratio of TEOS to MTES was found to be a crucial factor. Mesoporous characteristics of synthesized materials were investigated via BET surface area analysis, small angle X-ray diffraction, and FT-IR spectroscopy. At an optimal molar ratio (20:1) of TEOS and MTES, an 88% enhancement of <I>k</I> <SUB>L</SUB> <I>a</I> for methane in water was observed at 30°C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Methyl-functionalized silica SBA-15 were synthesized and characterized. </LI> <LI> Synthesized materials were employed as additives in aqueous solution. </LI> <LI> Enhanced methane–water volumetric mass transfer coefficient was observed. </LI> <LI> 88% enhancement of <I>k</I> <SUB>L</SUB> <I>a</I> for methane in water was observed. </LI> </UL> </P>

Controlled synthesis of SnS_xSe_2−x nanoplate alloys via synergetic control of reactant activity and surface defect passivation control with surfactant and co-surfactant mixture

Won, Jong Kook,Hwang, Chahwan,Ahn, Kyunghan,Choi, Seong-Young,Lee, Yongkyu,Kim, Jaehyun,Lee, Yangjin,Park, Sung Kyu,Chung, In,Kim, Choongik,Kim, Kwanpyo,Ahn, Sang Hyun,Lee, Min Hyung,Kim, Myung-Gil Elsevier 2019 Journal of solid state chemistry Vol.278 No.-

<P><B>Abstract</B></P> <P>Two-dimensional (2D) metal dichalcogenide nanomaterials have been receiving enormous research interest for electronic, optoelectronic, and catalytic applications. However, the facile tunability of alloying and doping, as well as the successful formation of ideal defect-free nanoplate morphology have been hardly achieved for 2D nanomaterials. Herein, we successfully synthesized a series of 2D solid-solution SnS<SUB>x</SUB>Se<SUB>2−x</SUB> particles of 0.20–2.00 μm width and 30–68 nm thickness with morphological defect-free nanoplate via a solvothermal reaction. With controlled reactivities of elemental chalcogen precursors, a co-surfactant hexylamine together with a structure-directing agent polyvinylpyrrolidone was found to be essential for realizing ideal defect-free nanoplate morphology of SnS<SUB>x</SUB>Se<SUB>2−x</SUB> particles without either cabbage-like or twinned structure. The successful synthesis of morphologically defect-free SnS<SUB>x</SUB>Se<SUB>2−x</SUB> nanoplates with rationally controlled energy band gaps ranging from 1.36 eV for SnSe<SUB>2</SUB> to 1.96 eV for SnS<SUB>2</SUB> could provide promising materials for electronics, optoelectronics, and electrocatalytic applications.</P> <P><B>Graphical abstract</B></P> <P>With chalcogen source control and surfactant/co-surfactant usage, morphologically defect free SnS<SUB>x</SUB>Se<SUB>2−x</SUB> nanoplates alloys were synthesized by facile solvothermal reaction.</P> <P>[DISPLAY OMISSION]</P>

Revie : Biocatalytic Conversion of Methane to Methanol as a Key Step for Development of Methane-Based Biorefineries

( In Yeub Hwang ),( Seung Hwan Lee ),( Yoo Seong Choi ),( Si Jae Park ),( Jeong Geol Na ),( In Seop Chang ),( Choongik Kim ),( Hyun Cheol Kim ),( Yong Hwan Kim ),( Jin Won Lee ),( Eun Yeol Lee ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.12

Methane is considered as a next-generation carbon feedstock owing to the vast reserves of natural and shale gas. Methane can be converted to methanol by various methods, which in turn can be used as a starting chemical for the production of value-added chemicals using existing chemical conversion processes. Methane monooxygenase is the key enzyme that catalyzes the addition of oxygen to methane. Methanotrophic bacteria can transform methane to methanol by inhibiting methanol dehydrogenase. In this paper, we review the recent progress made on the biocatalytic conversion of methane to methanol as a key step for methane-based refinery systems and discuss future prospects for this technology.

A Historical Research on the Characteristics of Large-scale Disasters in Korea

Choongik Choi,Chul Min Kim 위기관리 이론과 실천 2016 Crisisonomy Vol.12 No.4

본 연구의 목적은 해방 이후 한국사회에서 발생한 대형재난의 특징과 변화를 역사적 관점에서 살펴보는데 있다. 한국사회에서 발생한 주요 재난에 대해 발견적 탐색 기법으로 역사적 흐름과 변화과정을 다루고자 하였다. 연구범위는 1945년에서 2015년까지 발생한 대형재난을 대상으로 하였으며 모두 360개의 대형재난 사고가 검색되었으며, 재난 유형별로는 선박사고가 158건, 육상교통사고가 98 건으로 높은 비중을 나타났다. 시기별 연구 결과 대형재난 발생에 대한 특징들을 요약하면 다음과같다. 첫째, 대형재난의 발생 원인이 대부분 경험부족과 관리능력 부족이었다는 점이다(1기, 1945-1960). 둘째, 경제성장과 더불어 사회간접자본이 확충되고 이에 따라 대형재난 역시 급격하게증가하였다는 점이다(2기, 1961-1980). 셋째, 육상사고는 줄어들었으나 항공기 사고 등이 크게 증가하였다는 점이다(3기, 1981-2000). 넷째, 국내 대형재난 발생 건수는 급격하게 감소했지만 해외에서의 대형재난 발생은 증가하고 있다는 점이다(4기, 2001-2015). This study aims to explore the characteristics of large-scale disaster accidents using a historical approach, by assessing the main features of natural disasters in Korea by a heuristic method. We searched 360 large-scale disaster accidents in Korea occurred from 1945 to 2015 including 158 maritime accidents and 98 land transportation accidents. The results provide several important implications as follows. Firstly, most of accidents before 1960s were caused mainly by the lack of experience and management skills. Secondly, large-scale disasters increased dramatically along with economic growth and urbanization during the period from 1961 to 1980. Thirdly, it is notable that land transportation accidents decreased, while aircraft accidents increased during the period 1981 to 2000. Fourthly, the frequency of domestic large-scale disasters has been decreasing since 2000, whereas that of overseas large-scale disasters has been increasing.