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투명 차폐 필름 구현을 위한 전도성 복합 바인더의 입자구조에 따른 성능 평가
박지원 ( Ji-won Park ),백종호 ( Jong-ho Back ),이태형 ( Tae-hyung Lee ),김현중 ( Hyun-joong Kim ) 한국접착및계면학회 2017 접착 및 계면 Vol.18 No.2
스마트 모바일 산업의 성장에 따라 부품의 집적화가 가속화 되고 있다. 이러한 부품의 집적화는 부품간의 간섭현상문제를 야기했으며, 이를 해결하기 위한 전자파 차폐 기술의 중요성이 부각되고 있다. 전자파 차폐 기술은 전자파를 반사하거나 흡수하는 방식으로 구현되며, 일반적으로 전도성 물질이 전자파 차폐에 활용된다. 최근 산업의 변화에 따라 투명 차폐기술이 요구되고 있으며, 본 연구에서는 임프린팅 기술을 활용한 음각 구조 패턴에 전도성 복합 바인더를 충진 하여 투명 차폐소재를 제안하고자 하였다. 전도성 복합 바인더를 제조하기 위하여 UV 중합 아크릴 바인더를 활용하고 전도성 부여를 위해 구상, 판상 및 적층상의 은 입자를 활용하였다. 은 입자의 구조적인 특징에 따라 경화특성, 전도성 그리고 접착력의 변화를 확인하였다. 경화과정에서는 구상 입자의 활용이 가장 효율적이었으며, UV에 취약한 구조를 보완할 추가적인 경화 시스템이 요구되었다. 전도성평가에서는 적층상 구조가 우수한 특성을 보였다. 접착력은 구상이 가장 우수한 특성을 보였으며, 표면에서의 불규칙성에 따른 결과로 평가된다. 최종적으로 이를 활용한 패턴필름은 우수한 투명특성을 보여주었다. Recently, integration of parts is accelerating according to the growth of the smart mobile industry. The integration of these parts causes problems of interference phenomena between the parts, and the importance of electromagnetic wave shielding technology to solve this problem is highlighted. Electromagnetic wave shielding technology is implemented so as to reflect or absorb electromagnetic waves, and generally conductive materials are utilized for electromagnetic wave shielding. Transparent shielding technology is required according to recent industrial changes. In this research, we propose transparent the shielding film using imprint technology with conductive composite binder. Utilizing UV polymerized acrylic binder to produce a conductive composite binder. Spherical, plate and stacked silver particles were used for conductivity. The changes of the curing characteristics, conductivity and adhesion were observed according to the structural characteristics of the silver particles. The use of spherical particles was the most efficient in the curing process, and an additional curing system was required to complement the UV-shadowing structure. In the conductivity evaluation, the stacked structure showed excellent characteristics. The adhesion of spherical system was the best. It is evaluated as a result of irregularities on the surface. Ultimately, the patterned film using this showed excellent transparency characteristics.
Park, Ji-Won,Lee, Tae-Hyung,Back, Jong-Ho,Jang, Seong-Wook,Kim, Hyun-Joong,Skrifvars, Mikael Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.167 No.-
<P><B>Abstract</B></P> <P>We fabricated a new composite material with increased lyocell (a form of rayon that consists of cellulose fiber made from dissolving wood pulp) content through a surface hydrophobic treatment using phenyl silane and fiber carding/melt pressing. A matrix of polylactic acid (PLA) was used to enhance the environment-friendly properties of the composite and a carding process was used to orient the fibers in the composite. The lyocell content was controlled from 10% to 90%. Cross direction (CD) and machine direction (MD) samples were prepared to confirm the effect of the fiber directionality of the composite on its mechanical properties. The MD samples performed better than the CD samples. The tensile, flexural, and impact strengths of the composite were increased by approximately 85%, 155%, and 55%, respectively, after surface treatment. In the heat-resistance evaluation, confirmed by pyrolysis, surface treatment showed an average improvement of more than 10 °C. The water-absorption characteristics showed dramatic improvement, with enhanced surface-wetting properties and excellent initial moisture-absorption properties in the immersion test. Based on the comprehensive results, we conclude that the performance of the composite was satisfactory even when the content of lyocell was 50% or more.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper deals with the development of environmentally friendly green composite materials using regenerated cellulose Lyocell and PLA fibers. </LI> <LI> By using carding/melt pressing process technology, it was possible to obtain lyocell rich composite material. </LI> <LI> Phenyl silane surface treatment technology is very effective in improving internal bonding strength of composite materials. </LI> <LI> Through directional control, composite with very good strength in mechanical direction were produced. </LI> <LI> Mechanical properties, heat resistance and water resistance tend to increase with surface treatment. </LI> <LI> This technology will be a good example to maximize the content of naturally based fillers. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
화농성 근염과 감염성 대동맥류로 진행한 Klebsiella pneumoniae 간농양 1예
김주형,김지은,백수영,구태연,이경아,정경희,김현철,김혜영,배현주 대한감염학회 2008 감염과 화학요법 Vol.40 No.6
Klebsiella pneumonias causes pyogenic infections in various sites, with the risk of which increases in patients with diabetes mellitus. Recently, K. pneumoniae has emerged as a leading cause of pyogenie liver abscess, Primary liver abscess caused by K. pneumoniae in the absence of underlying hepatobiliary disease is commonly associated with metastatic infections such as endophthalmitis, meningitis, brain abscess and infection in other sites. We experienced a case of K. pneumonias liver abscess associated with septic metastatic lesions including pyomyositis and infected aneurysm of aorta. Despite the aggressive management with antibiotics, surgical pus drainage and aortic bypass graft, patient died of ventilator associated pneumonia and multiorgan failure. Our experience suggests that clinicians should be alert to septic metastatic infections when they treat a patient with K. pneumonias liver abscess.
김동형(Dong-Hyung Kim),최윤성(Youn-Sung Choi),김현국(Hyeonguk Kim),전명재(Myoungjae Jun),백성훈(Sunghoon Back),이용석(Yongseok Lee),이지영(Ji Yeong Lee),한창수(Chang-Soo Han) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.3
This paper proposes an algorithm for the trajectory planning of a dual-arm robot. Since the original collision-free path obtained in a probabilistic manner is unnecessarily jerky, it may induce high acceleration in the robot’s actuators, so we regard this as a low-quality path. We propose a B-spline trajectory planning algorithm that transforms the path into a collision-free and smooth trajectory to improve its quality. We applied our proposed algorithm to a cell-phone assembly task using a dual-arm robot as a specific application example. The simulation results show that the smooth and collision-free trajectories can be generated for the task with our motion planning simulator.
Dasom Jung,Jae Back Jung,Seulgi Kang,Ke Li,Inseon Hwang,Ji Hoon Jeong,Hyung Sik Kim,Jeongmi Lee(이정미) 한국분석과학회 2021 학술대회논문집 Vol.2021 No.11
Deep eutectic solvents (DESs) are formed from two or more components that are capable of hydrogen bonding. Because many constituents of DESs are naturally occurring and of low toxicity, the resulting DESs are often regarded safe. Recent studies reporting DES toxicity led us to systematically investigate the potential toxicity of a variety of DESs of which components are GRAS by FDA. The hydrogen bond donor was varied among organic acids (lactic acid and malic acid), polyols (glycerol, xylitol, and sorbitol), sugars (glucose and fructose), and urea, while the hydrogen bond acceptor was fixed as choline chloride (ChCl). The eight DESs were tested on HepG2 and HEK293T cell lines, and their IC50 values were compared with those of the aqueous solutions of individual components and mixtures. The aqueous mixtures of DES components generally showed lower IC50 than those of the individual components. Moreover, DESs usually exhibited similar to or higher cytotoxicities than the aqueous mixtures. For further in vivo toxico-metabolomics investigation, a DES, namely CU (1:2) consisting of ChCl and urea at 1:2 molar ratio was selected, because it is one of the most commonly applied DESs in diverse areas. Mice were grouped into five classes, each of which underwent oral administration of saline, ChCl, urea, aqueous solution of ChCl and urea, and CU (1:2). The acute oral toxicity was examined from serum, kidney, and liver by gas chromatography-mass spectrometry- and liquid chromatography-tandem mass spectrometry-based analysis. Metabolic profiles of the DES-treated mice were generally distinct from those of the other groups. Orthogonal projection to latent structure discriminant analysis allowed us to identify numerous differential metabolites, which imply the association of DES toxicity with oxidative and ammonia stresses. DES-induced oxidative stress was confirmed by superoxide dismutase activity, catalase activity, and malondialdehyde assays. Ammonia stress was evidenced by significantly increased ammonia levels in serum of the DES-treated mice. Ammonia could be produced from heating ChCl and urea and from heating ChCl and organic acids. Taken together, our study suggests that ChCl-based DESs may not be simply considered as pure and safe mixtures. The current presentation is based on our recent publication in Green Chemistry (2021).