Investigation of degradation pathways of poly(semiperfluoroalkyl methacrylate) thin films induced by electron‐beam irradiation

Jung, Seok‐,Heon,Chuluunbandi, Khajidkhand,Kim, Youngtae,Son, Jongchan,Oh, Hyun‐,Taek,Lee, Jin Hyun,Lee, Jin‐,Kyun,Beom‐,Hoan, O John WileySons, Inc. 2018 Journal of polymer science Part A, Polymer chemist Vol.56 No.23

<P><B>ABSTRACT</B></P><P>In this article, we report the results of high‐energy electron beam (e‐beam) irradiation of polymer thin films made of poly(semiperfluoroalkyl methacrylate)s <B>(PR</B><SUB><B>F</B></SUB><B>MA</B>s<B>)</B> and propose plausible chemical reactions that may cause their solubility to change in fluorous liquids. It was observed that the polymer films were converted to a more soluble state under low exposure doses of e‐beam, possibly due to main‐chain scission. However, the films became insoluble with higher doses of e‐beam. Three hypotheses were proposed to explain the reduction in solubility, and we used data from Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, mass spectrometry (MS), and nanoindentation to eliminate the less probable hypotheses. The results derived from e‐beam‐irradiated thin films of three <B>PR</B><SUB><B>F</B></SUB><B>MA</B>s showed that the radical‐related Norrish Type I and II pathways may not be the main decomposition routes. The data also suggested that sufficient scission reactions of the perfluorooctyl moieties of <B>PR</B><SUB><B>F</B></SUB><B>MA</B>s do not occur by e‐beam. We therefore assumed that the decrease in solubility of the fluorinated polymers results from intermolecular crosslinking reactions between the free radicals and reactive moieties generated on the perfluorooctyl groups by the e‐beam. The unique imaging mechanism of <B>PR</B><SUB><B>F</B></SUB><B>MA</B>s may be developed further to synthesize radiation‐sensitive materials working under e‐beam and extreme ultraviolet (λ = 13.5 nm) lithography conditions for advanced patterning applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. <B>2018</B>, <I>56</I>, 2672–2680</P>

Association of Changes in Mood Status and Psychosocial Well-Being with Depression During Interferon-Based Treatment for Hepatitis C

JungSeok Choi,Won Kim,BoKyung Sohn,JunYoung Lee,HeeYeon Jung,Sohee Oh,SaeKyoung Joo,HwiYoung Kim,YongJin Jung 대한신경정신의학회 2017 PSYCHIATRY INVESTIGATION Vol.14 No.3

Objective-The aims of this prospective study were to investigate temporal changes in mood status and distress level, as well as the development of depression, during pegylated interferon (PEG-IFN)-based treatment of patients with chronic hepatitis C (CHC). We also explored whether baseline demographic, psychiatric, and personality traits predicted the evolution of depression. Methods-CHC patients without depression were screened with laboratory tests; psychiatric interviews; and evaluations of mood symptoms, level of distress, and personality traits. A total of 67 treatment-naïve patients with CHC were consecutively treated with PEG-IFN-α-2a plus ribavirin for 48 (genotype 1, n=29) or 24 (genotype 2, n=38) weeks. Patients were followed prospectively every 4 weeks during the treatment period. Results-Seven patients (10.4%) were diagnosed with major depressive disorder (MDD), and eight (11.9%) developed subsyndromal depression. Times to onset of MDD and subsyndromal depression were 6.67±5.01 and 11.11±5.58 weeks, respectively, after initiation of treatment. Patients who developed MDD had significantly increased fatigue and anxiety and poor psychological well-being during the course of treatment. Pretreatment subthreshold mood symptoms were a significant predictor of depression. Conclusion-An early psychiatric assessment may be helpful in improving psychological well-being in those with CHC, leading to adherence to PEG-IFN-based treatment.

Phase Transition of Octaneselenolate Self-assembled Monolayers on Au(111) Studied by Scanning Tunneling Microscopy

Jungseok Choi,강훈구,Eisuke Ito,Masahiko Hara,노재근 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8

We investigated the surface structure and wetting behavior of octaneselenolate self-assembled monolayers (SAMs) on Au(111) formed in a 50 μM ethanol solution according to immersion time, using scanning tunneling microscopy (STM) and an automatic contact angle (CA) goniometer. Closely-packed, well-ordered alkanethiol SAMs would form as the immersion time increased; unexpectedly, however, we observed the structural transition of octaneselenolate SAMs from a molecular row phase with a long-range order to a disordered phase with a high density of vacancy islands (VIs). Molecularly resolved STM imaging revealed that the missing-row ordered phase of the SAMs could be assigned as a (6 × √3)R30° superlattice containing three molecules in the rectangular unit cell. In addition, CA measurements showed that the structural order and defect density of VIs are closely related to the wetting behaviors of octaneselenolate SAMs on gold. In this study, we clearly demonstrate that interactions between the headgroups and gold surfaces play an important role in determining the physical properties and surface structure of SAMs.

Formation and Role of Self Assembled Monolayer in Organic Thin Transistors

Jungseok Hahn 한국표면공학회 2007 한국표면공학회 학술발표회 초록집 Vol.2007 No.-

고분자 반도체를 이용한 유기 박막트랜지스터(OTFT) 소자 제작시 특성 향상을 위해 Self-Assemble Monolayer (SAM)을 이용한 유기 Gate 절연막과 source/drain 전극의 표면처리에 대해 설명하였다. Gate insulator의 경우 소수성 SAM이 고분자 반도체와의 상호작용으로 배열도를 향상시켜 이동도를 증가시켰으며, 전극 처리의 경우 접촉저항을 낮추어 injection을 증대시키는 효과를 나타내었다. 각각의 경우 적용되는 SAM 재료와 효과를 극대화시키기 위한 처리공정 전반에 대해 설명하였다.

Succinate Production from CO2-grown Microalgal Biomass as Carbon Source Using Engineered Corynebacterium glutamicum through Consolidated Bioprocessing

Jungseok LEE,Sang Jun SIM,Michael BOTT,Youngsoon UM,Min-Kyu OH,Han Min WOO 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

Flood risk awareness and property values: evidences from Seoul, South Korea

Jungseok Seo,Jihun Oh,Jeongseob Kim 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.2

There is ongoing debate about flood risk discounts regarding property values. While some researchers claim that housing prices reflect flood risk, a growing body of literature has shown that flood risk is quickly forgotten after a flood event, and risk discounts are minimal in the long term. This study provides new evidence of flood risk discounts, with an emphasis on the role of flood risk awareness based on the case of Seoul, South Korea. This paper empirically examines how flood risk discounts vary depending on past flood experiences, and analyzes whether they are affected by the disclosure of inundation hazard maps. According to the results, flood risk discounts are disproportionally higher in districts with severe past flood experiences, but interestingly, there is no evidence that negative disclosure effects of hazard information on property values exist. These findings imply that home buyers carefully consider flood risk in their housing transactions in high flood risk areas, even before hazard maps become available, possibly because having flood insurance is rare in South Korea. Understanding the relationship between flood risk awareness and risk discounts in terms of property values has vital implications for disaster management policies as they relate to cities’ resilience.

Self-Assembled Monolayers of Dioctyl Diselenides on Au(111)

Jungseok Choi,Yoon Jung Lee,강훈구,한진욱,노재근 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.6

The surface structure, electrochemical behavior, and wetting property of self-assembled monolayers (SAMs) formed by dioctyl diselenide (DODSe) on Au(111) were investigated by scanning tunneling microscopy (STM), cyclic voltammetry (CV), and contact angle measurements. In contrast to the formation of well-ordered SAMs by octanethiol on Au(111), the SAMs formed by DODSe have a disordered phase and many unusual vacancy islands (VIs). In addition, the formation of DODSe SAMs is largely influenced by the solution concentration used. DODSe SAMs formed in 5 μ M and 50 μ M solutions have two mixed domains consisting of missing-row ordered phases and disordered phases, while DODSe SAMs formed in 1 mM and 5 mM solutions have only disordered phases with an abnormally high VI fraction of 22-24%. We also found that the wetting property and electrochemical behavior of DODSe SAMs on Au(111) are markedly influenced by the formation of ordered SAMs and the density of VIs.

Automatic Parking System using Background Subtraction with CCTV Environment

Jungseok Cho,Jinrak Park,Untae Baek,Donghyun Hwang,Seibum Choi,Soohyun Kim,Kyungsoo Kim 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

In this paper, a new automatic parking approach that uses a surveillance camera is suggested. Many parking lots have surveillance cameras. Vehicle position, attitude, and parking space detection methods using a based on CCTV environment are introduced. An entire auto parking system is realized using a small experimental vehicle. Existing auto parking systems are primarily ADAS (advanced driver assistance systems) that use extra sensors such as external cameras, ultrasonic sensors, and so on. The authors suggest an automatic parking system that does not impose an economic burden on drivers. Instead, drivers can use an automatic parking system based on CCTV environment, a central process computer, and a communication method between the computer and the driver’s car.

Characteristics of Pig Carcass and Primal Cuts Measured by the Autofom Ⅲ Depend on Seasonal Classification

Jungseok Choi,Kimun Kwon,Youngkyu Lee,Eunyoung Ko,Yongsun Kim,Yangil Choi 한국축산식품학회 2019 한국축산식품학회지 Vol.39 No.2

The objective of this study was to investigate slaughtering performance, carcass grade, and quantitative traits of cuts according to seasonal influence by each month in pigs slaughtered in livestock processing complex (LPC) slaughterhouse in Korea, 2017. A total of 267,990 LYD (Landrace×Yorkshire×Duroc) pig data were used in this study. Results of slaughter heads, sex distribution, carcass weight, backfat thickness, grading class, total weight, and fat and lean meat percentages of each cut predicted by Autofom Ⅲ were obtained each month. The number of slaughtered pigs was the highest in early and late fall but the lowest in midsummer. Only in midsummer that the number of females was higher than that of castrates. During 2017, carcass weight was the lowest in late summer. Backfat thickness was in the range of 21–22 mm. In mid and late spring, pigs showed high 1+ grade ratio (37.05% and 36.15%, respectively). For traits of 11 cuts predicted by Autofom Ⅲ, porkbelly showed lower total weight, lean weight, and fat weight in midsummer to early fall but higher lean meat percentage compared to other seasons. Weights of deboned neck, loin, and lean meat were the highest in midfall compared to other seasons (p<0.05). In conclusion, characteristics of slaughtering, grading, and economic traits of pigs seemed to be highly seasonal. They were influenced by seasons. Results of this study could be used as basic data to develop seasonal specified management ways to improve pork production.

중국 유통산업과 산업연관분석

최정석 ( Jungseok Choi ),김형근 ( Hyunggeun Kim ) 사단법인 아시아문화학술원 2020 인문사회 21 Vol.11 No.6

본 연구는 중국 유통산업이 과거 글로벌 생산기지에서 소비시장으로 전환되고 있는 상황에서, 중국 2017년 산업연관표를 활용하여 유통산업의 경제적 효과를 분석하고, 이를 통해 중국유통산업에 대한 발전 전망을 조망하는데 그 배경과 목적이 있다. 본 논문의 분석결과는 다음과 같다. 첫째, 영향력계수 결과를 보면, 기존 전통제조업에서 3차 서비스산업으로의 이전과정에서 한층 업그레이드되어 더욱 구체적으로 진행되고 있다고 생각할 수 있다. 둘째, 감응도계수 결과를 보면, 중국정부의 일대일로 정책이 더욱 구체화되고 진전이 있는 산업군으로 변화되고 있음을 알 수 있다. 다만 본 연구의 한계점으로는 항상 거론되고 있는 분석 시점이 현재시점과 차이가 있다는 점을 들 수 있다. 왜냐하면 중국 투입산출표 발간자체가 평균 2-3년 정도 후에 이루어지기 때문에 현재의 산업연관관계를 분석하는데 애로사항이 있다고 볼 수 있다. This study analyzes the economic effects of the Chinese distribution industry using the 2017 industry link table in China in a situation where the Chinese distribution industry is transitioning from a global production base to a consumption market in the past, and through this, a prospect for the development of the Chinese distribution industry is forecast. It has its background and purpose. The analysis results of this paper are as follows. First, in the process of moving to the tertiary service industry, it can be considered that it has been further upgraded and is proceeding more specifically. Second, looking at the results of the sensitivity coefficient, it can be seen that the One Belt and One Road policy of the Chinese government is becoming more concrete than in the past. However, the limitation of this study is that there are difficulties in analyzing the current industry-related relations, since the publication of the input output table in China takes place on average 2-3 years later.