Selective Oxidative Degradation of Organic Pollutants by Singlet Oxygen-Mediated Photosensitization: Tin Porphyrin versus C₆₀ Aminofullerene Systems

Kim, Heechan,Kim, Wooyul,Mackeyev, Yuri,Lee, Gi-Seon,Kim, Hee-Joon,Tachikawa, Takashi,Hong, Seokwon,Lee, Sanghyup,Kim, Jungbae,Wilson, Lon J.,Majima, Tetsuro,Alvarez, Pedro J. J.,Choi, Wonyong,Lee, Ja American Chemical Society 2012 Environmental science & technology Vol.46 No.17

<P>This study evaluates the potential application of tin porphyrin- and C<SUB>60</SUB> aminofullerene-derivatized silica (SnP/silica and aminoC<SUB>60</SUB>/silica) as <SUP>1</SUP>O<SUB>2</SUB> generating systems for photochemical degradation of organic pollutants. Photosensitized <SUP>1</SUP>O<SUB>2</SUB> production with SnP/silica, which was faster than with aminoC<SUB>60</SUB>/silica, effectively oxidized a variety of pharmaceuticals. Significant degradation of pharmaceuticals in the presence of the 400-nm UV cutoff filter corroborated visible light activation of both photosensitizers. Whereas the efficacy of aminoC<SUB>60</SUB>/silica for <SUP>1</SUP>O<SUB>2</SUB> production drastically decreased under irradiation with λ > 550 nm, Q-band absorption caused negligible loss of the photosensitizing activity of SnP/silica in the long wavelength region. Faster destruction of phenolates by SnP/silica and aminoC<SUB>60</SUB>/silica under alkaline pH conditions further implicated <SUP>1</SUP>O<SUB>2</SUB> involvement in the oxidative degradation. Direct charge transfer mediated by SnP, which was inferred from nanosecond laser flash photolysis, induced significant degradation of neutral phenols under high power light irradiation. Self-sensitized destruction caused gradual activity loss of SnP/silica in reuse tests unlike aminoC<SUB>60</SUB>/silica. The kinetic comparison of SnP/silica and TiO<SUB>2</SUB> photocatalyst in real wastewater effluents showed that photosensitized singlet oxygenation of pharmaceuticals was still efficiently achieved in the presence of background organic matters, while significant interference was observed for photocatalyzed oxidation involving non-selective OH radical.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2012/esthag.2012.46.issue-17/es301775k/production/images/medium/es-2012-01775k_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es301775k'>ACS Electronic Supporting Info</A></P>

Development of Implementation Strategies for u-Health Services Based on the Healthcare Professionals' Experiences

Kim, Jeongeun,Kim, Sukwha,Kim, Heechan,Kim, Kyungwhan,Yang, Sukchul,Shin, Yoonju Mary Ann Liebert 2011 TELEMEDICINE JOURNAL AND E HEALTH Vol.17 No.2

액체산소/에탄올 엔진 연소시험 설비 구축 및 예비 운영 시험

김민상(Minsang Kim),전준수(Junsu Jeon),김태완(Taewoan Kim),우희찬(Heechan Woo),고영성(Youngsung Ko),김선진(Sunjin Kim),김승한(Seunghan Kim) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5

본 연구에서는 향후에 다양한 목적으로 사용될 수 있는 액체산소/에탄올 추진제 조합의 로켓 엔진 연소시험 설비를 구축하고, 이 설비에 대한 운용 능력을 평가하기 위하여 예비 운영 시험을 수행하였다. 추진제는 가압 방식에 의해 공급되며, 이를 위해 고압용 추진제 탱크와 가압 및 공급 설비를 구축하였다. 그리고 다중 분사기 엔진을 설계/제작하였으며, 수류시험과 실유체 분무 시험을 통해 이 엔진의 분무 특성과 유량 공급 특성을 관찰하였다. 최종적으로 연소시험을 통하여 액체산소/에탄올 엔진과 연소시험 설비의 안정성을 검증하였다. In this study, LOx/Ethanol rocket engine combustion test facility was constructed which can be used for various purpose in the future and preliminary operational tests were performed to evaluate the operational capability. The facility consists of run tanks, pressurization and supply system. Also a multi injector rocket engine was designed and manufactured and the engine’s cold flow and propellents spray tests were performed to observe spray and supply characteristics as well. Finally, stability of the LOx/Ethanol engine and combustion test facility were verified by combustion tests.

Document Summarization Model Based on General Context in RNN

( Heechan Kim ),( Soowon Lee ) 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.6

In recent years, automatic document summarization has been widely studied in the field of natural language processing thanks to the remarkable developments made using deep learning models. To decode a word, existing models for abstractive summarization usually represent the context of a document using the weighted hidden states of each input word when they decode it. Because the weights change at each decoding step, these weights reflect only the local context of a document. Therefore, it is difficult to generate a summary that reflects the overall context of a document. To solve this problem, we introduce the notion of a general context and propose a model for summarization based on it. The general context reflects overall context of the document that is independent of each decoding step. Experimental results using the CNN/Daily Mail dataset show that the proposed model outperforms existing models.

The relationship between spontaneous abortion and female workers in the semiconductor industry

Heechan Kim,Ho-Jang Kwon,Jeongbae Rhie,Sinye Lim,Yun-Dan Kang,Sang-Yong Eom,Hyungryul Lim,Jun-Pyo Myong,Sangchul Roh 대한직업환경의학회 2017 대한직업환경의학회지 Vol.29 No.-

Background: This study investigated the relationship between job type and the risk for spontaneous abortion to assess the reproductive toxicity of female workers in the semiconductor industry. Methods: A questionnaire survey was administered to current female workers of two semiconductor manufacturing plants in Korea. We included female workers who became pregnant at least 6 months after the start of their employment with the company. The pregnancy outcomes of 2,242 female workers who experienced 4,037 pregnancies were investigated. Personnel records were used to assign the subjects to one of three groups: fabrication process workers, packaging process workers, and clerical workers. To adjust for within-person correlations between pregnancies, a generalized estimating equation was used. The logistic regression analysis was limited to the first pregnancy after joining the company to satisfy the assumption of independence among pregnancies. Moreover, we stratified the analysis by time period (pregnancy in the years prior to 2008 vs. after 2009) to reflect differences in occupational exposure based on semiconductor production periods. Results: The risk for spontaneous abortion in female semiconductor workers was not significantly higher for fabrication and packaging process workers than for clerical workers. However, when we stratified by time period, the odds ratio for spontaneous abortion was significantly higher for packaging process workers who became pregnant prior to 2008 when compared with clerical workers (odds ratio: 2.21; 95% confidence interval: 1.01–4.81). Conclusions: When examining the pregnancies of female semiconductor workers that occurred prior to 2008, packaging process workers showed a significantly higher risk for spontaneous abortions than did clerical workers. The two semiconductor production periods in our study (prior to 2008 vs. after 2009) had different automated processes, chemical exposure levels, and working environments. Thus, the conditions prior to 2008 may have increased the risk for spontaneous abortions in packaging process workers in the semiconductor industry.

Document Summarization Model Based on General Context in RNN

Kim, Heechan,Lee, Soowon Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.6

In recent years, automatic document summarization has been widely studied in the field of natural language processing thanks to the remarkable developments made using deep learning models. To decode a word, existing models for abstractive summarization usually represent the context of a document using the weighted hidden states of each input word when they decode it. Because the weights change at each decoding step, these weights reflect only the local context of a document. Therefore, it is difficult to generate a summary that reflects the overall context of a document. To solve this problem, we introduce the notion of a general context and propose a model for summarization based on it. The general context reflects overall context of the document that is independent of each decoding step. Experimental results using the CNN/Daily Mail dataset show that the proposed model outperforms existing models.

Relationship between residential district and health-related quality of life in Chungnam industrial complex area

Kim, Heechan,Roh, Sangchul The Korean Society of Environmental Toxicology 2016 환경독성보건학회지 Vol.31 No.-

Objectives This study aimed to evaluate the relationship between residential district of people, such as power plant, steel-mill and petrochemical industries, and health-related quality of life (HRQoL). Methods Using a cross-sectional study design, we randomly recruited participants for our study from industrial areas (thermoelectric power plant, steel-mill, petrochemical industry) and rural areas. Logistic regression analysis was used to identify the relationships between Euro quality of life-5 dimension (EQ-5D) scores and living region, while controlling for sociodemographic characteristics. Results In adjusted model, quality of life decreased with increasing category of age and were lower for females than males. EQ-5D scores of people living in the vicinity of thermoelectric power plant were significant lower than those of people living the vicinity of comparison region (odds ratio, 1.59; 95% confidence interval, 1.00 to 2.53). Conclusions Living region of thermoelectric power plant, was strongly associated with scores on the EQ-5D. More research is needed to elucidate the mechanisms which makes the relationship with the living regions and HRQoL.

Study on magnon-contribution to unidirectional spin Hall magnetoresistance in HM/FM bilayer structures

Heechan Jang,Eunkang Park,Seyeop Jeong,Donghyun Lee,Jisu Kim,Kwangsu Kim,Nyun Jong Lee,Chun-Yeol You,Sanghoon Kim 한국자기학회 2020 한국자기학회 학술연구발표회 논문개요집 Vol.30 No.2

Cascade proton relays facilitate electron transfer across hydrogen-bonding network

Kim Heechan,Lee Dongwhan 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.4

Functioning as both hydrogen-bonding donor and acceptor, the imidazole group of histidine holds a unique position in the proton transfer cascade of biological systems. For example, a histidine residue in the oxygen-evolving photosystem II participates in the proton-coupled electron transfer (PCET) reaction to facilitate light-triggered one-electron oxidation of a nearby tyrosine residue. As a minimalist synthetic model of such His–Tyr functional diad, three structural variants of benzimidazole–phenol conjugate were studied. We found that an increasing number of hydrogen bonds facilitate reversible one-electron oxidation of the phenol ring. The reaction coordinates of this intriguing PCET process were mapped out by density functional theory computational studies to reveal oxidation-driven conformational switching as an entry point to cascade proton relays stabilizing the phenoxyl radical. Strategic placement of hydrogen bonds thus tightly regulates the energy windows of electron transfer, which is an effective strategy for biological redoxphores of seemingly limited structural diversity.

Relationship between residential district and health-related quality of life in Chungnam industrial complex area

Heechan Kim,Sangchul Roh 환경독성보건학회 2016 환경독성보건학회지 Vol.31 No.-

Objectives This study aimed to evaluate the relationship between residential district of people, such as power plant, steel-mill and petrochemical industries, and health-related quality of life (HRQoL). Methods Using a cross-sectional study design, we randomly recruited participants for our study from industrial areas (thermoelectric power plant, steel-mill, petrochemical industry) and rural areas. Logistic regression analysis was used to identify the relationships between Euro quality of life-5 dimension (EQ-5D) scores and living region, while controlling for sociodemographic characteristics. Results In adjusted model, quality of life decreased with increasing category of age and were lower for females than males. EQ-5D scores of people living in the vicinity of thermoelectric power plant were significant lower than those of people living the vicinity of comparison region (odds ratio, 1.59; 95% confidence interval, 1.00 to 2.53). Conclusions Living region of thermoelectric power plant, was strongly associated with scores on the EQ-5D. More research is needed to elucidate the mechanisms which makes the relationship with the living regions and HRQoL.