Flexible artificial synesthesia electronics with sound-synchronized electroluminescence

Kim, Jong Sung,Cho, Sung Hwan,Kim, Kang Lib,Kim, Gwangmook,Lee, Seung Won,Kim, Eui Hyuk,Jeong, Beomjin,Hwang, Ihn,Han, Hyowon,Shim, Wooyoung,Lee, Tae-Woo,Park, Cheolmin Elsevier 2019 Nano energy Vol.59 No.-

<P><B>Abstract</B></P> <P>Visualization of human senses has been of great interest for developing an emerging interactive display that can artificially stimulate synesthesia with numerous unprecedented applications. Especially, visualization of various daily sound and music, which are much more complicated than human touch, in a form of flexible thin film devices can be a great challenge. We present flexible artificial synesthesia electronics that visualize continuous and complicated sounds. The electronic device is made of a thin composite film of a piezoelectric polymer for sound generation and inorganic electroluminescence (EL) microparticles for direct visualization of input sound signals. Field-induced EL of the microparticles in the device depends upon the source sound wave, making their EL synchronized with sound arising from the piezoelectric actuation. The flexible artificial synesthesia devices with sound-synchronized EL (FASSEL) showed extreme mechanical tolerance that can be repeatedly folded and crumpled with visible sound, allowing a variety of unexplored applications including synchronous sound-lightings and wearable, on-body sound-vision systems to facilitate emotional interaction of human being with sound in a human-friendly form.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ultra-flexible piezoelectric loudspeakers were developed with sound synchronized EL. </LI> <LI> Piezoelectric polymer composite with EL particles for direct visualization of sound. </LI> <LI> Artificial synesthesia of sound and vision via a single capacitive device platform. </LI> <LI> Silica-encapsulated-ZnS particle was employed for high EL with low leakage current. </LI> <LI> Extreme mechanical tolerance that can be repeatedly folded and crumpled. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A Study of the Reliability and Validity of the Korean Version of the Penn Alcohol Craving Scale for Alcohol-Dependent Patients

MinJeong Kim,SungGon Kim,HyoJeong Kim,HoChan Kim,JiHeh Park,KwangSeok Park,DukKi Lee,WonTan Byun,CheolMin Kim 대한신경정신의학회 2008 PSYCHIATRY INVESTIGATION Vol.5 No.3

Objective-The Penn Alcohol Craving Scale (PACS) is a stronger predictor of subsequent drinking and relapse of alcohol dependence that can be administered more quickly and easily than other craving scales. The goal of this study was to develop the Korean version of the Penn Alcohol Craving Scale (PACS-K). Methods-To examine the psychometric properties of the PACS-K, responses were chosen from 80 patients admitted to a treatment facility for alcohol dependence. Results-The PACS-K possesses good psychometric properties, as assessed by Cronbach’s α estimates (Cronbach’s α=0.91). The test-retest reliability of the PACS-K showed high correlation (p<0.01) when the retest interval was 1 day. When the validity of the PACS-K was investigated using correlation analysis with two other craving scales (the Obsessive Compulsive Drinking Scale (OCDS) and the Visual Analogue Scale (VAS), high correlations were obtained between total PACS scores and total OCDS scores, and between total PACS scores and VAS scores (p<0.01, respectively). Conclusion-The PACS-K is a reliable and valid measure of alcohol cravings, and it could be useful for predicting which individuals are at risk for subsequent relapse.

Diamond structure-dependent pad and wafer polishing performance during chemical mechanical polishing

Shin, Cheolmin,Kulkarni, Atul,Kim, Kangjun,Kim, Hojoong,Jeon, Sanghuck,Kim, Eungchul,Jin, Yinhua,Kim, Taesung Springer-Verlag 2018 INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TE Vol.97 No.1

Molecularly Engineered Surface Triboelectric Nanogenerator by Self-Assembled Monolayers (METS)

Song, Giyoung,Kim, Younghoon,Yu, Seunggun,Kim, Min-Ook,Park, Sang-Hee,Cho, Suk Man,Velusamy, Dhinesh Babu,Cho, Sung Hwan,Kim, Kang Lib,Kim, Jongbaeg,Kim, Eunkyoung,Park, Cheolmin American Chemical Society 2015 Chemistry of materials Vol.27 No.13

<P>Self-powered energy harvesters utilizing triboelectric effect and electrostatic induction have been widely studied, leading in the materials viewpoint to numerous material pairs for facile charge separation upon repetitive contacts with elaborate topological structures. Here, we present a simple but robust triboelectric platform based on a molecularly engineered surface triboelectric nanogenerator by self-assembled monolayers (METS). Triboelectric surface charge density of a substrate was readily controlled by the variation of end-functional groups of self-assembled monolayers (SAMs). In particular, by employing fluorine terminated SAMs, we are able to develop a METS with the maximum open circuit voltage and short circuit current of 105 V and 27 μA, respectively, under relatively gentle mechanical contacts with the 3N vertical force at 1.25 Hz. The power density of the device was 1.8 W/m<SUP>2</SUP> at the load resistance of 10 MΩ more than 60 times greater than that of an unmodified dielectric/Al device. Moreover, our approach with SAMs was extended to various types of surfaces including fabrics of silk, cotton, and poly(ethylene terephthalate) (PET) and a PET film, and the results of single-friction-surface triboelectric nanogenerators with these materials offers a facile and universal guideline for designing triboelectic materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-13/acs.chemmater.5b01507/production/images/medium/cm-2015-01507p_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b01507'>ACS Electronic Supporting Info</A></P>

Cloning metallothionein gene in Zacco platypus and its potential as an exposure biomarker against cadmium.

Lee, Sangwoo,Kim, Cheolmin,Kim, Jungkon,Kim, Woo-Keun,Shin, Hyun Suk,Lim, Eun-Suk,Lee, Jin Wuk,Kim, Sunmi,Kim, Ki-Tae,Lee, Sung-Kyu,Choi, Cheol Young,Choi, Kyungho D. Reidel Pub. Co ; Springer 2015 Environmental monitoring and assessment Vol.187 No.7

<P>Zacco platypus, pale chub, is an indigenous freshwater fish of East Asia including Korea and has many useful characteristics as indicator species for water pollution. While utility of Z. platypus as an experimental species has been recognized, genetic-level information is very limited and warrants extensive research. Metallothionein (MT) is widely used and well-known biomarker for heavy metal exposure in many experimental species. In the present study, we cloned MT in Z. platypus and evaluated its utility as a biomarker for metal exposure. For this purpose, we sequenced complete complementary DNA (cDNA) of MT in Z. platypus and carried out phylogenetic analysis with its sequences. The transcription-level responses of MT gene following the exposure to CdCl2 were also assessed to validate the utility of this gene as an exposure biomarker. Analysis of cDNA sequence of MT gene demonstrated high conformity with those of other fish. MT messenger RNA (mRNA) expression and enzymatic MT content significantly increased following CdCl2 exposure in a concentration-dependent manner. The level of CdCl2 that resulted in significant MT changes in Z. platypus was within the range that was reported from other fish. The MT gene of Z. platypus sequenced in the present study can be used as a useful biomarker for heavy metal exposure in the aquatic environment of Korea and other countries where this freshwater fish species represents the ecosystem.</P>

Optimized Solvent Vapor Annealing for Long-Range Perpendicular Lamellae in PS-<i>b</i>-PMMA Films

Kim, Kyunginn,Park, Sungmin,Kim, Yeongsik,Bang, Joona,Park, Cheolmin,Ryu, Du Yeol American Chemical Society 2016 Macromolecules Vol.49 No.5

<P>We report a simple approach to fabricating highly stable, perpendicularly oriented lamellae through the self-assembly of high-molecular-weight polystyrene-bpoly(methyl methacrylate) (PS-b-PMMA). Using a solvent vapor annealing (SVA) process controlled by modulating the temperature gap between the chamber and bottom plate, followed by a subsequent thermal annealing process, the ordering stability of perpendicularly oriented lamellae was investigated. The temperature gap that regulates the solvent absorption and dewetting times of the swollen block copolymer (BC?) films was adjusted to enable the films to wet a neutral substrate, thereby facilitating ordering and structural development with no ordering failure. An optimized SVA process at a selected temperature gap of 5 degrees C was found to display the excellent long-term stability, at which highly ordered line arrays composed of perpendicularly oriented lamellae were confined to large-width (3.2 mu m) topographic line patterns. This study also provides the effective time window for the SVA process, suggesting a simple and efficient route to fabricating long-range lateral ordering in BCP self-assembled structures.</P>

Investigation of the pad-conditioning performance deterioration in the chemical mechanical polishing process

Kim, Hojoong,Hong, Seokjun,Shin, Cheolmin,Jin, Yinhua,Lim, Dong Hyun,Kim, Jun-yong,Hwang, Hasub,Kim, Taesung Elsevier 2017 Wear: An international journal on the science and Vol.392 No.-

<P>The surface roughness of a chemical mechanical polishing (CMP) pad provides microscopic asperities where the actual polishing takes place. Thus, the roughness should be maintained in a proper regimen to obtain stable CMP process quality. A conditioner is a key consumable in the CMP process because it maintains the roughness of the CMP pad surface against surface glazing or flattening during polishing. Because the conditioner mechanically breaks the pad surface to maintain the roughness, previous research has expressed its ability index in terms of the pad wear rate (PWR). In the present study, we investigate the reason for PWR change of CMP pads having vigorously changing moduli with respect to temperature changes during the mass production. The pad property changed steeply in the process temperature range from 60 to 80 degrees C. The tensile strength is a key property change that leads to sudden PWR drop. We found that the shape and configuration of the diamond tip are the major parameters affecting the ability to maintain surface roughness of the pads. Thus, we suggested a proper conditioner design for tungsten (W) CMP based on the experimental data to sustain the process quality and increase the consumable lifetime. As a result, the peak surface roughness has improved from 29.4 mu m to 32.6 mu m and the consumable lifetime was also increased.</P>

Development of Fruit Harvest Basket and Assessment of its Effectiveness

Cheolmin Lim,Kyungsuk Lee,Kyungran Kim,Hyocher Kim,Sungwoo Kim,Mintae Seo,Hyeseon Chae 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.5

The purpose of this study is to develop products that prevent muscular skeletal disease of farm workers, which would bring improvement for an efficient harvesting work. A pretest for product development and a survey research was carried out to inspect the problems of current harvesting work procedure. The product was developed and assessed based on ideas to supplement and improve these weak points. A total of twenty men were recruited to evaluate the effects of harvest baskets on the upper-limb muscle activities. For the usability evaluation, electromyogram of previous working method(disuse of harvest basket , one-hand carriage of the basket) and new working method with the usage of newly-developed harvest basket was examined. The whole anterior deltoid, biceps brachii and erector spinae on both sides, which makes a total of six muscle parts, were used for this experiment. The results were analyzed using ANOVA with muscle activity(%MVC) of each three forms of work and required work time from SPSS 18.0. According to the test result, all muscles did not demonstrate any statistically significant difference, with an exception of the backbone erector(right). The muscle activity of backbone erector(right) in the work method that uses harvest basket was detected to be approximately 23% less than that of the previous working method. As such, the decrease in the amount of waist muscle usage at harvesting work would enable the prevention of muscular skeletal disease and stabilization of lumbar spine. Which in turn would increase the effectiveness and reduce personnel expense(labor costs) while enhancing productivity with a decreased working hours.

Micropatterns of Non‐Circular Droplets of Nanostructured PS‐<i>b</i>‐PEO Copolymer by Solvent‐Assisted Wetting on a Chemically Periodic Surface

Kim, Tae Hee,Park, Youn Jung,Song, Giyoung,Kim, Dong Ha,Huh, June,Karthaus, Olaf,Park, Cheolmin WILEY‐VCH Verlag 2012 Macromolecular chemistry and physics Vol.213 No.4

<P><B>Abstract</B></P><P>A method to fabricate micropatterns of non‐circular droplets of a self‐assembled block copolymer by solvent‐assisted wetting on chemically periodic surface is presented. The block copolymer is dewetted on a topographic pre‐pattern to form an array of microdroplets with a sphere‐capped shape and circular contact line. The droplets are then transferred onto a chemically periodic Au line pattern microcontact‐printed with two types of self‐assembled monolayers (SAMs). Solvent vapor application provides sufficient mobility to the block copolymer molecules to induce spreading of the transferred droplets, resulting in two types of non‐circular microdroplet growth. The growth behavior depends on the size of initial droplets relative to periodic line width and on the initial registries of as‐transferred droplets.</P>

Biodegradable, electro-active chitin nanofiber films for flexible piezoelectric transducers

Kim, Kyungtae,Ha, Minjeong,Choi, Byeongwook,Joo, Se Hun,Kang, Han Sol,Park, Ju Hyun,Gu, Bongjun,Park, Chanho,Park, Cheolmin,Kim, Jongbok,Kwak, Sang Kyu,Ko, Hyunhyub,Jin, Jungho,Kang, Seok Ju Elsevier 2018 Nano energy Vol.48 No.-

<P><B>Abstract</B></P> <P>Since the conventional fluorine-based electro-active polymers release toxic residues into the environment during their syntheses and decomposition processes, eco-friendly piezoelectric polymers are urgently demanded in the field of energy-related soft materials. Here, we derive a high-performance biodegradable chitin polymer from squid pen material and demonstrate its utility as a flexible piezoelectric material. The readily controlled ferroelectric chitin film confers excellent piezoelectricity under external mechanical pressure, resulting in comparable performance with that of conventional fluorine-based piezoelectric polymers. In particular, the sufficient piezoelectric behavior in chitin film allows us to not only realize a high-fidelity paper-type speaker and microphone that operates over a wide frequency range without significantly deteriorating the input and output sounds but also demonstrate transparent speaker consisting of AgNWs electrodes onto freestanding chitin film which also enables to resemble the original sound. Finally, the biodegradable chitin polymer can be successfully dissolved by chitinase enzyme within eight days without any toxic residues remained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ferroelectric characteristic is confirmed by polarization measurement. </LI> <LI> β-chitin film enables to demonstrate high-fidelity paper-type speaker and microphone. </LI> <LI> The biodegradable nature of chitin film can be dissolved within eight days. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>We present a novel biodegradable piezoelectric material from chitin material, the second-most abundant polysaccharide biopolymer. The decent polarization arising from the chitin molecules not only facilitates the piezoelectric response upon the external pressure but also generates the harmonic frequencies of the input music source. Moreover, the environmentally friendly chitin film can be completely dissolved in a water-based solution without generating toxic products.</P> <P>[DISPLAY OMISSION]</P>