Direct Observation of Interfacial Morphology in Poly(3-hexylthiophene) Transistors: Relationship between Grain Boundary and Field-Effect Mobility

Choi, Danbi,Jin, Sangwoo,Lee, Youngmin,Kim, Se Hyun,Chung, Dae Sung,Hong, Kipyo,Yang, Chanwoo,Jung, Jungwoon,Kim, Jin Kon,Ree, Moonhor,Park, Chan Eon American Chemical Society 2010 ACS APPLIED MATERIALS & INTERFACES Vol.2 No.1

<P>We investigated the effects of microstructural (crystallization and molecular orientation) and morphological alternation (grain boundary) of poly(3-hexylthiophene) (P3HT) films on the field-effect mobility (μ) before (as-spun P3HT) and after (melt-crystallized P3HT) melting of P3HT films. Although grazing incidence X-ray scattering shows that melt-crystallized P3HT has a more highly ordered edge-on structure than as-spun P3HT, the melt-crystallized P3HT reveals μ = 0.003 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>; this is an order of magnitude lower than that of as-spun P3HT (μ = 0.01 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>). In addition, the interfacial morphologies of the bottom surfaces of P3HT films, which are attached to the gate dielectric, were investigated using a film transfer technique. The melt-crystallized P3HT at this interface consists of well-developed nanowire crystallites with well-defined grain boundaries that act as trap states, as verified by analysis of the temperature-dependence of μ. The remarkable reduction of μ in low-molecular-weight P3HT film (8 kg/mol) that results from melt-crystallization is due to the increased number of well-defined grain boundaries.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2010/aamick.2010.2.issue-1/am9005385/production/images/medium/am-2009-005385_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am9005385'>ACS Electronic Supporting Info</A></P>

High-Performance Triisopropylsilylethynyl Pentacene Transistors via Spin Coating with a Crystallization-Assisting Layer

Choi, Danbi,Ahn, Byungcheol,Kim, Se Hyun,Hong, Kipyo,Ree, Moonhor,Park, Chan Eon American Chemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.1

<P>The effects of spin speed and an amorphous fluoropolymer (CYTOP)-patterned substrate on the crystalline structures and device performance of triisopropylsilylethynyl pentacene (TIPS-PEN) organic field-effect transistors (OFETs) were investigated. The crystallinity of the TIPS-PEN film was enhanced by decreasing the spin speed, because slow evaporation of the solvent provided a sufficient time for the formation of thermodynamically stable crystalline structures. In addition, the adoption of a CYTOP-patterned substrate induced the three-dimensional (3D) growth of the TIPS-PEN crystals, because the patterned substrate confined the TIPS-PEN molecules and allowed sufficient time for the self-organization of TIPS-PEN. TIPS-PEN OFETs fabricated at a spin speed of 300 rpm with a CYTOP-patterned substrate showed a field-effect mobility of 0.131 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, which is a remarkable improvement over previous spin-coated TIPS-PEN OFETs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-1/am201074n/production/images/medium/am-2011-01074n_0007.gif'></P>

Effect of Solvent-Assisted Dispersions of Clay/Epoxy Nanocomposites on Steel Passivation

Choi, Danbi,Park, Chan Eon,Yang, Seung Yun,Kim, Haekyoung,Kim, Se Hyun American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.1

<P>Dispersion of clay in polymer matrices is important to improve their engineering performances. Here we report the effect of solvent on dispersion of montmorillonite (MMT) in an epoxy matrix by examining transmission electron micrographs and X-ray diffraction of MMT/epoxy composites prepared with solvents with different polarities. We found that N-metyl-2-pyrrolidone (NMP) used as a polar solvent exhibited the improved dispersion of MMT in the epoxy owing to positive interaction energies with components, which prevents the aggregation of MMT platelets. The solvent-assisted dispersion of MMT significantly increased the corrosion resistance of MMT/epoxy nanocomposites pre-coated onto steel plates.</P>

웹 기반 협업 개체명 태깅 도구

최단비(Danbi Choi),김예원(Yewon Kim),김장원(Jangwon Gim) 한국정보기술학회 2020 Proceedings of KIIT Conference Vol.2020 No.10

개체명 인식 기술은 문서 내 중요한 의미를 지니고 있는 개체명을 추출하여 인명, 기관명, 기술명 등으로 분류하여 요약, 기계번역 분야에서 유용하게 사용된다. 그러나 개체명 인식 기술 중 하나인 개체명 태깅 과정은 태깅을 수행하는 작업자의 배경지식, 어휘 이해도 등이 다르기 때문에 동일한 단어가 다른 개체명으로 태깅될 수 있는 문제점이 있다. 본 논문에서는 개체명 태깅 및 검토 기능을 개발하고, 작업자에 의해 태깅된 통계 결과를 시각화할 수 있는 웹 기반 협업 개체명 태깅 도구를 제안한다. 그 결과 협업을 통해 효율적으로 개체명 태깅을 할 수 있는 시스템을 구축하였다. The entity name recognition technology is useful in the fields of summary and machine translation by extracting entity names that have important meanings in a document and classifying them into human names, organization names, technical names, etc. However, the entity name tagging process, which is one of the entity name recognition technologies, has a problem in that the same word may be tagged with a different entity name because the background knowledge and vocabulary comprehension of the tagging worker are different. In this paper, we develop an entity name tagging and review function, and propose a web based collaborative entity name tagging tool that can visualize statistical results tagged by workers. As a result, we built a system that can efficiently tag entity names through collaboration.

사회적 약자를 위한 공공데이터 통합 및 분석 방법 사례 연구

최단비(Danbi Choi),김예원(Yewon Kim),김장원(Jangwon Gim) 한국정보기술학회 2021 Proceedings of KIIT Conference Vol.2021 No.6

최근 다양한 공공데이터가 공유 및 활용되어 이를 활용한 서비스들이 급증하고 있다. 그렇지만 많은 수의 공공데이터가 공개된 것에 비하여 공공데이터의 연계를 통한 서비스 또는 지역별 특징을 반영한 정책 등을 위한 공공데이터의 활용이 다소 미흡하다. 따라서 본 논문에서는 공공데이터를 이용하여 사회적 약자 지원을 위한 서비스를 제안한다. 이를 위해 각 지역의 공공데이터를 수집, 통합 및 분석하고 사회적 약자를 지원하는 서비스의 빈도를 고려한 점수를 계산하여 지역별 차이를 도출한다. 그 결과 수도권에 위치한 시도지역 보다 비수도권 지역이 사회적 약자 지원 서비스를 위한 점수가 상대적으로 낮음을 알 수 있다. 본 논문에서 제안한 방법을 통해 각 지역에서 공개된 공공데이터들의 상호 연계를 통해 지역 맞춤형 서비스 및 정책을 수립이 가능함을 보이며 또한, 향후 전국 단위의 공공데이터 통합 및 분석 서비스의 기반 연구로 활용 가능할 것으로 보인다. Recently, various public data has been shared and utilized, and services using it are increasing rapidly. However, compared to the fact that much public data has been disclosed, the use of public data for services through linkage of public data or policies reflecting regional characteristics is insufficient. Therefore, in this paper, we propose a service to support the socially underprivileged using public data. In this paper, we collect, integrate, and analyze public data of each region and calculate the score considering the frequency of services supporting the socially disadvantaged to derive regional differences. As a result, it can be seen that the score for support services for the socially underprivileged in the non-metropolitan area is relatively lower than that of the urban area located in the metropolitan area. Through the proposed model, it is possible to establish regional customized services and policies through mutual interlinking of public data disclosed in each region. In addition, it is expected to be used as basic research for national public data integration and analysis services in the future.

Development of Machine Learning-Based Clinical Decision Support System for Hepatocellular Carcinoma

( Gwang Hyeon Choi ),( Jihye Yun ),( Jonggi Choi ),( Danbi Lee ),( Ju Hyun Shim ),( Young-suk Lim ),( Han Chu Lee ),( Young-hwa Chung ),( Yung Sang Lee ),( Beomhee Park ),( Namkug Kim ),( Kang Mo Kim 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: There is a significant discrepancy between the actual choice for initial treatment option for hepatocellular carcinoma (HCC) and recommendations from the currently used BCLC staging system. The aim of this study is to develop a machine learning-based clinical decision support system (CDSS) for recommending initial treatment option in HCC and predicting overall survival (OS). Methods: From hospital records of 1021 consecutive patients with HCC treated at a single center in Korea between January 2010 and October 2010, we collected information on 61 pretreatment variables, initial treatment, and survival status. Twenty pretreatment key variables were finally selected. We developed the CDSS from the derivation set (N=813) using random forest method and validated it in the validation set (N=208). Results: Among the 1021 patients (mean age: 56.9 years), 81.8% were male and hepatitis B virus was positive in 77.0%. Patients with BCLC stages 0, A, B, C, and D were 13.4%, 26.0%, 18.0%, 36.6%, and 6.3%, respectively. The 6 multistep classifier models were developed for treatment decision in a hierarchical manner, and it showed good performance with 76.6-88.4% of accuracy. We also developed 7 survival prediction models for each treatment option, which showed good prediction ability for OS with C-index values ranging from 0.684-0.959. Conclusions: Our newly developed HCC-CDSS model showed good performance in terms of treatment recommendation and overall survival prediction. Our HCC-CDSS model may be used as a guidance in deciding the initial treatment option for HCC.

Kinetics of the Neutrophil-Lymphocyte Ratio during PD-1 Inhibition as a Prognostic Factor in Advanced Hepatocellular Carcinoma

( Won-mook Choi ),( Ji Yoon Kim ),( Jonggi Choi ),( Danbi Lee ),( Ju Hyun Shim ),( Young-suk Lim ),( Han Chu Lee ),( Changhoon Yoo ),( Min-hee Ryu ),( Baek-yeol Ryoo ),( Kang Mo Kim ) 대한간학회 2021 춘·추계 학술대회 (KASL) Vol.2021 No.1

Effects and Safety of Nivolumab in Child-Pugh B Patients with Hepatocellular Carcinoma: A Retrospective Cohort Study

( Won-mook Choi ),( Jonggi Choi ),( Danbi Lee ),( Ju Hyun Shim ),( Kang Mo Kim ),( Young-suk Lim ),( Han Chu Lee ),( Changhoon Yoo ),( Sook Ryun Park ),( Min-hee Ryu ),( Baek-yeol Ryoo ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Nivolumab showed durable response and safety in patients with hepatocellular carcinoma (HCC) in the previous trials. However, real-world data of nivolumab in HCC patients, especially those with Child-Pugh class B, is lacking. We aimed to investigate the efficacy and safety of nivolumab in a real- world cohort of patients with advanced HCC. Methods: This study retrospectively evaluated 203 patients with HCC who were treated with nivolumab between July 2017 to February 2019. Radiologic evaluation was based on mRECIST. Survival outcomes were estimated by Kaplan-Meier method and Cox proportional hazard model. Logistic regression model was used to identify the predictive factors of treatment response. Results: Of 203 patients, 132 patients were within Child-Pugh class A and 71 patients were within Child-Pugh class B. Objective response rate was lower in patients with Child-Pugh class B than A (2.8% vs. 15.9%; P=0.010 by unweighted analysis and P=0.034 by weighted analysis) and Child-Pugh class was an independent predictor for objective response (Odds ratio, 0.21; 95% confidence interval; 0.05-0.93; P=0.040). Median overall survival was shorter in Child-Pugh B patients (11.3 vs. 42.9 weeks; P<0.001 by both unweighted and weighted analyses). However, other efficacy outcomes including disease control rate, time to progression, and progression-free survival were comparable between Child-Pugh A and B patients by unadjusted, adjusted, matched, and weighted analyses. There was no significant difference in terms of safety between Child-Pugh A and B patients. Conclusions: Given the limited treatment options for advanced HCC in Child-Pugh B patients, nivolumab may be a viable option despite lower response in these patients. Further studies are needed in this patient population.

Regorafenib versus Nivolumab after Sorafenib Failure: Real-World Data in Patients with Hepatocellular Carcinoma

( Won-mook Choi ),( Jonggi Choi ),( Danbi Lee ),( Ju Hyun Shim ),( Young-suk Lim ),( Han Chu Lee ),( Young-hwa Chung ),( Young-sang Lee ),( Sook Ryun Park ),( Min-hee Ryu ),( Baek-yeol Ryoo ),( So Jun 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Regorafenib and nivolumab are drugs approved for second-line treatment of patients with hepatocellular carcinoma (HCC) after sorafenib failure. However, the effectiveness of regorafenib and nivolumab following sorafenib has not been directly compared. Methods: This study retrospectively evaluated 373 patients with HCC who were treated with regorafenib (n=223) or nivolumab (n=150) after sorafenib failure between July 2017 and February 2019. Results: Progression-free survival (PFS; hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.69-1.06; P=0.150), time to progression (TTP; HR, 0.95; 95% CI, 0.77-1.19; P=0.680), and overall survival (OS; HR, 0.83; 95% CI, 0.64-1.07; P=0.154) did not differ significantly between groups of patients treated with regorafenib and nivolumab, findings consistently observed by multivariable-adjusted, propensity score-matched, and inverse probability treatment weighting (IPTW) analyses. However, the objective response rate was significantly higher in the nivolumab than in the regorafenib group (13.3% vs, 4.0%; P=0.002). When the effectiveness of regorafenib and nivolumab was compared in non-progressors to treatment, defined as patients who achieved complete response, partial response, or stable disease after first response evaluation, PFS (HR, 0.50; 95% CI, 0.33-0.75; P=0.001), TTP (HR, 0.48; 95% CI, 0.31-0.73; P<0.001), and OS (HR, 0.51; 95% CI, 0.31-0.87; P=0.013) were significantly longer in the 59 non-progressors to nivolumab than in the 104 non-progressors to regorafenib, findings also observed by multivariable-adjusted and IPTW analyses. Conclusions: Survival outcomes in patients treated with regorafenib and nivolumab after sorafenib failure did not differ significantly. However, nivolumab may be more effective than regorafenib in non-progressors.

A Systematic Review and Meta-Analysis of Applicability of Web-Based Interventions for Individuals with Depression and Quality of Life Impairment

Danbi Yang,Ji-Won Hur,Yoo Bin Kwak,Sung-Won Choi 대한신경정신의학회 2018 PSYCHIATRY INVESTIGATION Vol.15 No.8

Objective_The purpose of this meta-analysis was to determine the applicability of web-based treatment programs for individuals with depression and quality of life impairments. Methods_We conducted database and manual searches using imprecise search-term strategy and inclusion criteria. Research published from 2005 to December 2015 was included in this study. Upon review, a total of 12 published papers on web-based intervention for individuals with depression were assessed eligible for this meta-analysis. Effect sizes were estimated for depression and quality of life. Results_The mean effect size of web-based treatment on depressive symptoms was 0.72. However, unlike the result showing medium to large effect size, the analysis on the quality of life did not yield adequate effects of web-based interventions. Conclusion_Our results suggest robust benefits of employing web-based treatments for depressive symptoms. However, the adequacy of these relatively new intervention tools for individuals who suffer severe impairments of quality of life was found insufficient. The current study demonstrates the need to further develop web-based intervention techniques to improve overall functioning, as well as the clinical symptoms of patients with mental disorders.