• Science of Emotion and Sensibility
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• v.21 no.3
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• pp.165-176
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• 2018

The objective of this study was to develop clothing-type wearable motion sensing and feedback systems to enhance children's sports by promoting visual and audio feedback. In this study, several applications, such as fabric sensors, sportswear integrated with various types of fabric sensors, and fabric-based motion sensing module design, as well as a visual and audio feedback system for gaining a better understanding of a child's interest in a type of exercise, were developed. An SWCNT-based stretchable fabric sensor was developed for motion sensing, and sportswear was designed using the fabric sensor that was integrated into the limbs of the garment. The sensing module was developed, and sensory performance was evaluated through a joint motion experiment for children. In addition, using the feedback system that was developed in the form of an accessory, the responses of light and sound were also examined based on the movement of the child who was wearing the sportswear prototypes. This study focused on the development and assessment of prototype designs for children's sportswear and accessory products that can help to ascertain a child's interest in a particular exercise.

• Journal of Environmental Science International
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• v.25 no.4
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• pp.505-516
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• 2016

With the development of nanotechnology, nanomaterials are used in various fields. Therefore, the interest regarding the safety of nanomaterial use is increasing and much effort is diverted toward establishment of exposure assessment and management methods. Occupational exposure limits (OELs) are effectively used to protect the health of workers in various industrial workplaces. This study aimed to propose an OEL for domestic multi-walled carbon nanotubes (MWCNTs) based on animal inhalation toxicity test. Basic procedure for development of OELs was examined. For OEL estimation, epidemiological study and quantitative risk assessment are generally performed based on toxicity data. In addition, inhalation toxicity data-based no observed adverse effect level (NOAEL) and benchmark dose (BMD) are estimated to obtain the OEL. Three different estimation processes (NEDO in Japan, NIOSH in USA, and Baytubes in Germany) of OELs for carbon nanotubes (CNTs) were intensively reviewed. From the rat inhalation toxicity test for MWCNTs manufactured in Korea, a NOAEL of $0.98mg/m^3$ was derived. Using the simple equation for estimation of OEL suggested by NEDO, the OEL of $142{\mu}g/m^3$ was estimated for the MWCNT manufacturing workplace. Here, we used test rat and Korean human data and adopted 36 as an uncertainty factor. The OEL for MWCNT estimated in this work is higher than those ($2-80{\mu}g/m^3$) suggested by previous investigators. It may be greatly caused by different physicochemical properties of MWCNT and their dispersion method and test rat data. For setting of regulatory OELs in CNT workplaces, further epidemiological studies in addition to animal studies are needed. More advanced technical methods such as CNT dispersion in air and liquid should be also developed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.37-44
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• 2015

In this paper, we have investigated a selective assembly method of single-walled carbon nanotubes (SWCNTs) on a silicon substrate using only photolithographic process and then proposed a fabrication method of field effect transistors (FETs) using SWCNT-based patterns. The aminopropylethoxysilane (APTES) patterns, which are formed for positively charged surface molecular patterns, are utilized to assemble and align millions of SWCNTs and we can more effectively assemble on a silicon (Si) surface using this method than assembly processes using only the 1-octadecyltrichlorosilane (OTS). We investigated a selective assembly method of SWCNTs on a Si surface using surface-programmed APTES and OTS patterns and then a fabrication method of FETs. photoresist(PR) patterns were made using photolithographic process on the silicon dioxide (SiO2) grown Si substrate and the substrate was placed in the OTS solution (1:500 v/v in anhydrous hexane) to cover the bare SiO2 regions. After removing the PR, the substrate was placed in APTES solution to backfill the remaining SiO2 area. This surface-programmed substrate was placed into a SWCNT solution dispersed in dichlorobenzene. SWCNTs were attracted toward the positively charged molecular regions, and aligned along the APTES patterns. On the contrary, SWCNT were not assembled on the OTS patterns. In this process, positively charged surface molecular patterns are utilized to direct the assembly of negatively charged SWCNT on SiO2. As a result, the selectively assembled SWCNT channels can be obtained between two electrodes(source and drain electrodes). Finally, we can successfully fabricate SWCNT-based multi-channel FETs by using our self-assembled monolayer method.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.443-454
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• 2013

Various metal ions (transition and base metals) incorporated MCM-41 catalysts can be synthesized using colloidal and soluble silica with non-sodium involved process. Transition metal ion-typically $V^{5+}$, $Co^{2+}$, and $Ni^{2+}$-incorporated MCM-41 catalysts were synthesized by isomorphous substitution of Si ions in the framework. Each incorporated metal ion created a single species in the silica framework, single-site solid catalyst, showing a substantial stability in reduction and catalytic activity. Radius of pore curvature effect was investigated with Co-MCM-41 by temperature programmed reduction (TPR). The size of metallic Co clusters, sub-nanometer, could be controlled by a proper reduction treatment of Co-MCM-41 having different pore size and the initial pH adjustment of the Co-MCM-41 synthesis solution. These small metallic clusters showed a high stability under a harsh reaction condition without serious migration, resulting from a direct anchoring of small metallic clusters to the partially or unreduced metal ions on the surface. After a complete reduction, partial occlusion of the metallic cluster surface by amorphous silica stabilized the particles against aggregations. As a probe reaction of particle size sensitivity, carbon single wall nanotubes (SWNT) were synthesized using Co-MCM-41. A metallic cluster stability test was performed by CO methanation using Co- and Ni-MCM-41. Methanol and methane partial oxidations were carried out with V-MCM-41, and the radius of pore curvature effect on the catalytic activity was investigated.

• Science of Emotion and Sensibility
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• v.18 no.4
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• pp.25-34
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• 2015

TThis study explored the requirement of fabric sensor that can measure the motion of the joint effectively by measuring and analyzing the variation in electric resistance of a sensor in accordance with bending and stretching motion of the arm by the implementation of a motion sensor utilizing conductive fabric. For this purpose, on both sides of two kinds of knitted fabric, namely 'L' fabric and 'W' fabric Single Wall Carbon Nano-Tube(SWCNT) was coated, fabric sensor was developed by finishing them in a variety of ways, and the sensor was attached to the arm band. The fabric sensor consisted of total 48 cases, namely background fabric for coating, the method of sensor attachment, the number of layer of sensors, the length of sensor, and the width of sensor. The performance of fabric motion sensors in terms of a dummy arm, that is, a Con-Trex MJ with 48 arm bands around it was evaluated. For each arm band, a total of 48, fastened around the dummy arm, it was adjusted to repeat the bending and stretching at the frequency : 0.5Hz, ROM : $20^{\circ}{\sim}120^{\circ}$, the voltage was recorded for each case after conducting three sets of repeat measurement for a total of 48 cases. As a result of the experiment, and as a consequences of the evaluation and analysis of the voltage based on the uniformity of the base line of the peak-to-peak voltage(Vp-p), the uniformity of Vp-p within the same set, and the uniformity of the Vp-p among three sets, the fabric sensors that have been configured in SWCNT coated 'L' fabric / welding / two layers / $50{\times}5mm$, $50{\times}10mm$, $100{\times}10mm$, and SWCNT coated 'W' fabric / welding / two layers / $50{\times}10mm$ exhibited the most uniform and stable signal value within 5% of the total variation rate. Through all these results of the experiment, it was confirmed that SWCNT coated fabric was suitable for a sensor that can measure the human limb operation when it was implemented as a fabric sensor in a variety of forms, and the optimal sensor types were identified.

• Science of Emotion and Sensibility
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• v.22 no.4
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• pp.97-106
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• 2019

The purpose of this study was to investigate the effect of the type and measurement location of a fabric strain gauge sensor on the detection performance for respiratory signals. We implemented two types of sensors to measure the respiratory signal and attached them to a band to detect the respiratory signal. Eight healthy males in their 20s were the subject of this study. They were asked to wear two respiratory bands in turns. While the subjects were measured for 30 seconds standing comfortably, the respiratory was given at 15 breaths per minute were synchronized, and then a 10-second break; subsequently, the entire measurement was repeated. Measurement locations were at the chest and abdomen. In addition, to verify the performance of respiratory measurement in the movement state, the subjects were asked to walk in place at a speed of 80 strides per minute(SPM), and the respiratory was measured using the same method mentioned earlier. Meanwhile, to acquire a reference signal, the SS5LB of BIOPAC Systems, Inc., was worn by the subjects simultaneously with the experimental sensor. The Kruskal-Wallis test and Bonferroni post hoc tests were performed using SPSS 24.0 to verify the difference in measurement performances among the group of eight combinations of sensor types, measurement locations, and movement states. In addition, the Wilcoxon test was conducted to examine whether there are differences according to sensor type, measurement location, and movement state. The results showed that the respiratory signal detection performance was the best when the respiratory was measured in the chest using the CNT-coated fabric sensor regardless of the movement state. Based on the results of this study, we will develop a chest belt-type wearable platform that can monitor the various vital signal in real time without disturbing the movements in an outdoor environment or in daily activities.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.588-593
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• 2022

Terephthalaldehyde (TPA) is introduced as a cross liker to enhance electron transfer of hemin-based cathodic catalyst consisting of polyethyleneimine (PEI), carbon nanotube (CNT) for hydrogen peroxide reduction reaction (HPRR). In the cyclic voltammetry (CV) test with 10 mM H₂O₂ in phosphate buffer solution (pH 7.4), the current density for HPRR of the suggested catalyst (CNT/PEI/hemin/PEI/TPA) shows 0.2813 mA cm^-2 (at 0.2 V vs. Ag/AgCl), which is 2.43 and 1.87 times of non-cross-linked (CNT/PEI/hemin/PEI) and conventional cross liker (glutaraldehyde, GA) used catalyst (CNT/PEI/hemin/PEI/GA), respectively. In the case of onset potential for HPRR, that of CNT/PEI/hemin/PEI/TPA is observed at 0.544 V, while those of CNT/PEI/hemin/PEI and CNT/PEI/hemin/PEI/GA are 0.511 and 0.471 V, respectively. These results indicate that TPA plays a role in facilitating electron transfer between the electrodes and substrates due to the π-conjugated cross-linking bonds, whereas conventional GA cross-linker increases the overpotential by interrupting electron and mass transfer. Electrochemical impedance spectroscopy (EIS) results also display the same tendency. The charge transfer resistance (R_ct) of CNT/PEI/hemin/PEI/TPA decreases about 6.2% from that of CNT/PEI/hemin/PEI, while CNT/PEI/hemin/PEI/GA shows the highest R_ct. The polarization curve using each catalyst also supports the superiority of TPA cross liker. The maximum power density of CNT/PEI/hemin/PEI/TPA (36.34±1.41 μWcm^-2) is significantly higher than those of CNT/PEI/hemin/PEI (27.87±0.95 μWcm^-2) and CNT/PEI/hemin/PEI/GA (25.57±1.32 μWcm^-2), demonstrating again that the cathode using TPA has the best performance in HPRR.