산업단지 및 일반생활 지역의 공기 중 톨루엔에 대한 개인노출 및 생체시료의 상관성 분석

이병준(Byoungjun Lee),허 정(Jung Heo),정다영(Dayoung Jung),김순신(Sunshin Kim),류현수(Hyeon-Su Ryu),최민지(Min-Ji Choi),솨이지엔페이(Jian-Fei Shuai),임성국(Sung-Guk Im),양원호(Wonho Yang) 한국환경보건학회 2017 한국환경보건학회지 Vol.43 No.4

Objectives: The purpose of this study was to assess the correlation relationship between personal exposure and urinary hippuric acid in biological monitoring for airborne toluene in an industrial complex and in general environments. Methods: Personal exposure to toluene and its metabolite, hippuric acid, in urine were simultaneously measured in occupational environments area near an industrial complex and in general environments. The study subjects were divided into three types: 137 workers who use organic solvents in the workplace, 210 residents living near a dyeing industrial complex, and 379 residents living in general environments. The toluene exposures of workers and residents were measured by a passive sampler for four days. The urine of participants was sampled when the passive samplers of personal exposure were collected. Results: The toluene and hippuric acid concentrations of workers were the highest, followed by the concentrations of residents living near a dyeing industrial complex and residents living in general environments. The coefficient of correlation between the concentrations of toluene and hippuric acid among workers was 0.749 (p<0.01) in the workplace. On the contrary, correlations between the concentrations of toluene and hippuric acid among residents living near a dyeing industrial complex and residents living in general environments were all not significant. The relationship between the concentrations of hippuric acid and toluene in three types could be described by the exponential growth model. Conclusions: This study analyzed the relationships between toluene exposure and the concentrations of hippuric acid in urine in high, middle, and low exposure environments, and could be described by the exponential growth model.

Mechanically robust and high-performance ternary solar cells combining the merits of all-polymer and fullerene blends

Lee, Wonho,Kim, Jae-Han,Kim, Taesu,Kim, Seonha,Lee, Changyeon,Kim, Jin-Seong,Ahn, Hyungju,Kim, Taek-Soo,Kim, Bumjoon J. The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.10

<P>In this study, we demonstrate that the introduction of small amounts of phenyl-C71-butyric acid methyl ester (PC71BM) into all-polymer solar cells (all-PSCs) increases the photovoltaic performance without compromising mechanical properties. Ternary blend polymer solar cells (ternary-PSCs) consisting of a polymer donor (PTB7-Th) and an acceptor mixture with different weight ratios of a polymeric acceptor (P(NDI2HD-T2)) and PC71BM demonstrate the effects of PC71BM loading on the power conversion efficiency (PCE) and mechanical properties. A significant enhancement in the PCEs of ternary-PSCs, from 6.32% to 7.33%, is observed when PC71BM is added into the active layer as up to 30 wt% of the acceptor mixture. Importantly, the excellent mechanical properties (<I>i.e.</I>, crack onset strain = 11.6%, toughness = 2237 J m<SUP>−3</SUP>) of the blend films are well preserved at PC71BM loadings at or below 30 wt%. In contrast, both the PCE and the mechanical performance of the ternary-PSCs significantly decrease at higher PC71BM loadings (>50 wt%). Detailed morphological analysis<I>via</I>grazing incidence X-ray scattering measurements reveals that PC71BM molecules are well-dispersed in the amorphous portion of the active layer at PC71BM loadings up to 30 wt%. Therefore, both the mechanical and photovoltaic performances of the ternary-PSCs correlate closely with their morphological behavior, particularly in terms of the mixing behavior of PC71BM with polymers. The well-dispersed PC71BM molecules in the amorphous polymer domains facilitate efficient exciton dissociation, whereas the formation of PC71BM aggregates above a critical concentration causes severe mechanical degradation of the ternary-PSCs due to the presence of weak interfaces between the brittle PC71BM and polymer domains. Therefore, the ternary blends with optimal content of polymer/fullerene acceptors represent important candidates for flexible and wearable solar cells that require both high mechanical and photovoltaic performances.</P>

<i>Drosophila</i> Low Temperature Viability Protein 1 (LTV1) Is Required for Ribosome Biogenesis and Cell Growth Downstream of <i>Drosophila</i> Myc (dMyc)

Kim, Wonho,Kim, Hag Dong,Jung, Youjin,Kim, Joon,Chung, Jongkyeong American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.21

<P>During animal development, various signaling pathways converge to regulate cell growth. In this study, we identified LTV1 as a novel cell growth regulator in <I>Drosophila. LTV1</I> mutant larvae exhibited developmental delays and lethality at the second larval stage. Using biochemical studies, we discovered that LTV1 interacted with ribosomal protein S3 and co-purified with free 40S ribosome subunits. We further demonstrated that LTV1 is crucial for ribosome biogenesis through 40S ribosome subunit synthesis and preribosomal RNA processing, suggesting that LTV1 is required for cell growth by regulating protein synthesis. We also demonstrated that <I>Drosophila</I> Myc (dMyc) directly regulates <I>LTV1</I> transcription and requires LTV1 to stimulate ribosome biogenesis. Importantly, the loss of <I>LTV1</I> blocked the cell growth and endoreplication induced by dMyc. Combined, these results suggest that LTV1 is a key downstream factor of dMyc-induced cell growth by properly maintaining ribosome biogenesis.</P>

Tuning Mechanical and Optoelectrical Properties of Poly(3-hexylthiophene) through Systematic Regioregularity Control

Kim, Jin-Seong,Kim, Jae-Han,Lee, Wonho,Yu, Hojeong,Kim, Hyeong Jun,Song, Inho,Shin, Minkwan,Oh, Joon Hak,Jeong, Unyong,Kim, Taek-Soo,Kim, Bumjoon J. American Chemical Society 2015 Macromolecules Vol.48 No.13

<P>While the regioregularity (RR) of conjugated polymers is known to have a strong influence on their inherent properties, systematic study of the RR effect has been limited due to the lack of a synthetic methodology. Herein, we successfully produced a series of poly(3-hexylthiophene)s (P3HTs) having a wide range of RR from 64 to 98%. Incorporation of controlled amounts of head-to-head (H-H) coupled dimer in modified Grignard metathesis polymerization allows a facile tuning of the RR of the P3HTs with comparable molecular weight and low polydispersity. Then, we investigated the effect of RR on structural, electrical, and mechanical properties of P3HTs in which a higher content of H-H regio-defects, namely lower RR, systematically lowered the degree of crystallinity. Although high RR P3HT (98%) had higher charge carrier mobility (1.81 x 10(-1) cm(2) V-1 s(-1)), its strong crystallinity induced high brittleness and stiffness, resulting in device failure under a very small strain, as shown in tensile and bending tests. The tensile modulus was reduced significantly from 287 MPa (RR 98%) to 13 MPa (RR 64%), and also the RR 64% P3HT film had much better mechanical resilience with an order of magnitude higher elongation at break than that of the RR 98% polymer. Our findings suggest that the mechanical and electrical properties of conjugated polymers can be systematically tuned by controlling the RR to meet the purposes of various organic electronic applications, i.e., flexible portable devices vs high-performance panels.</P>

옥내 전력선망 분석을 위한 전력선 모델링과 사례 연구

김원호(Wonho Kim),황보훈(Hoon Hwangbo),나완수(Wansoo Nah),박일한(Il-han Park),김병성(Byung-Sung Kim),김창섭(Chang-Seob Kim) 대한전기학회 2005 대한전기학회 학술대회 논문집 Vol.2005 No.7

Vulcanizate Structures of NR Compounds with Silica and Carbon Black Binary Filler Systems at Different Curing Temperatures

( Il Jin Kim ),( Donghyuk Kim ),( Byungkyu Ahn ),( Hyung Jae Lee ),( Hak Joo Kim ),( Wonho Kim ) 한국고무학회 2021 엘라스토머 및 콤포지트 Vol.56 No.1

There is an increasing demand for the rolling resistance reduction in truck bus radial (TBR) tires in the tire industry. In TBR tires, natural rubber is used as a base polymer to prevent wear and satisfy required physical properties (cut and chip). A binary filler system (silica and carbon black) is used to balance the durability of the tire and rolling resistance performance. In this study, natural rubber (NR) compounds applied with a binary filler system were manufactured at different cure temperatures for vulcanizate structure analysis. The vulcanizate structures were categorized into carbon black bound rubber, silica silane rubber network, and chemical crosslink density by sulfur. Regardless of the cure temperature, the crosslink density per unit content of carbon black had a greater effect on the properties than silica due to affinity with NR. The relationship analysis between the mechanical, viscoelastic properties with vulcanizate structure could be a guideline for manufacturing practical TBR compounds.

Effect of interpass distance on the arc stability and its effect on the automated wire arc additive manufacturing of 5 Cr - 4 Mo tool steel

Jae-Deuk Kim(김재득),JooYong Cheon(천주용),JaeHun Kim(김재훈),JaeWon kim(김재원),Junsoo Kim(김준수),Hyunwook Jun(전현욱),Wonho Kim(김원호),Changwook Ji(지창욱) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5

Recently, global environmental regulations getting more strict, and hence it is increasing that the interest and investment of automobile companies on the aluminum die casting parts to make light-weight vehicles. Die casting molds are fabricated by the machining of billets of tool steels such as AISI 4140 or H13, in general. But, it has disadvantages like a large material loss and long lead time. Meanwhile, a Wire Arc Additive Manufacturing (WAAM) process could be an alternative fabrication method of the die casting mold. It has advantages such as less material loss, short lead time, easy repair and modification, the chance to make a reinforced mold using dissimilar materials, etc. The 5 Cr - 4 Mo tool steel wire is a commercial tool steel solid wire which designed for the repair and modification of tools and molds. It has superior hot wear resistance and toughness as well as the high strength, thus has high potential to produce die casting molds via the WAAM process. On the other hand, the WAAM process is basically the process that stacking the layers repetitively using a conventional arc welding process based on the designed tool paths by CAD/CAM. Thus, the predictability and the reproducibility of every single layer are the most important core factor to obtain the advantages of the automated WAAM process. Due to its nature, a new process parameter whose named an interpass distance should be considered as well as the conventional process parameters such as current, voltage, travel speed, etc. However, there are lack of researches on the interpass distance of WAAM process. In this research, it was found that the interpass distance greatly affect the arc stability due to arc interference induced by the variation of distance from the prior deposited pass. That is to say that the more arc interference was observed as the less interpass distance was given. This phenomenon had been proven through the analysis of high-speed camera results and the variation in the amount of spatter. Further, it was observed that the interpass distance affects the dimension precision and predictability of automated WAAM process of the 5 Cr - 4 Mo tool steel. And it was found the critical interpass distance that could be utilized in the automated WAAM process of the 5 Cr - 4 Mo tool steel. The effect of the interpass distance on the arc interference would exist unless the interpass distance would be given over 100 %, thus, it is important to find out a point of compromise based on the arc stability, dimension predictability, and reproducibility.

Effect of the functional group of silanes on the modification of silica surface and the physical properties of solution styrene-butadiene rubber/silica composites

Ahn, Byungkyu,Kim, Donghyuk,Kim, Kihyun,Kim, Il Jin,Kim, Hak Joo,Kang, Chang Hwan,Lee, Jong-Yeop,Kim, Wonho V.S.P 2019 COMPOSITE INTERFACES -ZEIST- Vol.26 No.7

호혜적 개발협력을 위한 주요 국가의 STI 시스템 분석 및 협력방향 - 브라질, 인도를 중심으로 -

김왕동(Wangdong Kim),임덕순(Deok Soon Yim),선인경(Inkyoung Sun),김은주(Eun Joo Kim),이다은(Daeun Lee),유제현(Jehyun Yu),이정원(Jung-won Lee),김기국(Ki-Kook Kim),최용인(Yongin Choi),김원호(Wonho Kim),조충제(Chungje Jo),박민경(Minkyoung P 과학기술정책연구원 2021 정책연구 Vol.- No.-

Reciprocal development cooperation refers to “all activities in the public and private sectors that benefit the donor country’s national interest as well as poverty eradication and economic and social development in the recipient country”. The Korean governments development cooperation paradigm is expected to gradually shift from a humanitarian level to a reciprocal level. However, in the case of science and technology innovation, it is difficult to acquire information about countries that are subject to reciprocal development cooperation. Therefore, in this study, the conceptual framework for reciprocal development cooperation was established and STI systems of major countries were analyzed to provide basic STI data and to suggest directions for reciprocal development cooperation. In this study, two countries, Brazil and India, were selected for analysis by applying three criteria: “differentiation from existing research,” “relevance to national interests and national tasks,” and “possibility of securing data”. In this study, the STI system components of Brazil and India were classified and analyzed into macro-environment, STI governance, STI investment and achievements, STI human resources, STI innovative actors, and STI support organizations. The reciprocal development cooperation agenda was described focusing on three dimensions: “what”, “how” and “who”. First, in the perspective of “what”, climate change, digital transformation, infectious diseases, and other issues were derived as cooperation contents. Second, policy advice and joint research, human exchange, and so on, were suggested as cooperation methods. Third, universities, GRIs, and companies were suggested as cooperation partners. Brazils STI system is characterized by a weak national R&D budget, excellent research manpower and strong basic research, lack of connection and creation of innovation demand between universities and companies, weak industrial competitiveness, lack of science and technology policy and strategy, policy implementation, and coordination of inefficiency and slow-step administration. The characteristics of the Indian STI system include inefficient governance and lack of interconnection led by the government, insufficient investment in STI between the government and the private sector, abundant STI manpower and global talent, the pursuit of R&D activities centered on universities and public research institutes rather than the private sector, bureaucratic and bureaucratic An inefficient STI support organization was identified. In-depth interviews and consultations were conducted with experts from each country to derive the Korea-Brazil development cooperation agenda and the Korea-India development cooperation agenda. The interview and advisory groups were largely divided into policymakers(public officials) for each country, researchers(researchers and professors), and local experts(embassies and dispatchers). The detailed agenda contents are described in Chapters 6 and 7. This study is expected to contribute to the theoretical construction of the field of development cooperation, and to the derivation of the governments Korea-Brazil and Korea-India STI cooperation agenda. The study also can contribute to the demand for STI system information of Brazil and India. However, this study has limitations in responding to more demand by the government by selecting Brazil and India as two countries for reciprocal development cooperation. Therefore many more countries besides Brazil and India should be explored in the future. In addition, in order to improve the reliability and validity of the STI cooperation agenda between Korea-Brazil and Korea-India, interviews and consultations with more experts are required.

Developmental characteristic of Tenebrio molitor larvae (Coleoptera: Tenebrionidae) in different larval instars

Jongbin Park,Namjung Kim,Wonho Choi,Seonghyun Kim,Hyojung Jin 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10

A Tenebrio molitor larva that is called mealworm is widely used as feed for raising a pet. Also, it is the insect that would be produced as the edible food for human. For these reasons, many researchers are revealing about physiologic characteristic of Tenebrio molitor to make good use of it. However, morphological characteristic of different larval stage is not specifically indicated and researchers have different opinions about the average number of Tenebrio molitor’s instar until now. This study, therefore, was carried out to examine the physiological and morphological characteristics of Tenebrio molitor larva in different larval stages, and the average number of Tenebrio molitor’s instar. As a result, all of the Tenebrio molitor larvae had 7~8 days during their incubation period and 3~4 days during the 1st instar period. After the 1st instar, there were comparatively large differences in the number of days in each instar. Before emergence, most of the larvae comparatively showed 15th~17th instars, particularly, the largest rate of pupae (28.83%) was observed in the 17th instar. In terms of the body length of each Tenebrio molitor larval stage, the body length was gradually increased by the 17th instar. Beyond the 17th instar, however, the body length was smaller than 17th instar. In the 1st instar, the larva had white color, and the color gradually changed into brown from the 2nd instar. Through this study, we could identify the accurate incubation period, 1st instar period, the average number of instar, body length and the color change in different larval stages. These results would be used as a fundamental data for further study about the physiological and morphological characteristic of each instar period.