Preparation of a Novel Microporous HDPE/ Zeolite Composite Film

Kim, Hyun,Jagannath, Biswas,Choi, Hyang Hee,Kim, Geon-Joung,Lee, Dai Soo,Choe, SoonJa 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.6

Novel microporous film of the zeolite filled HDPE composites prepared by a conventional compounding prccedure using a twin-screw extruder and followed by a simple stretching in a tensile test machine. Zeolite particles are well dispersed in HDPE matrix without a significant aggregation. m e Young's modulus values gradually increase, but the yield stress, impact strength and elongation at break decrease with zeolite contents in composite. Dewetting phenomenon is predominant around the zeolite particles, thereby zeolite seems to he acting as non-adhering filler. In addition, the X-ray diffractometer meaurement reveals that the crystallinity extremely reduced with zeolite contents. Thus, enlargement of the air holes upon stretching and merging between the neighboring air holes, and the reduced crystallinity is responsible for poor mechanical propnties. It is suggested that the size, number, and aspect ratio of the micropores should be controlled due to the zeolite contents in matrix and the degree of stretching.

Finger language recognition based on ensemble artificial neural network learning using armband EMG sensors

Kim, Seongjung,Kim, Jongman,Ahn, Soonjae,Kim, Youngho IOS Press 2018 Technology and health care Vol.26 No.1

<P><B>BACKGROUND:</B></P><P> Deaf people use sign or finger languages for communication, but these methods of communication are very specialized. For this reason, the deaf can suffer from social inequalities and financial losses due to their communication restrictions.</P><P><B>OBJECTIVE:</B></P><P> In this study, we developed a finger language recognition algorithm based on an ensemble artificial neural network (E-ANN) using an armband system with 8-channel electromyography (EMG) sensors.</P><P><B>METHODS:</B></P><P> The developed algorithm was composed of signal acquisition, filtering, segmentation, feature extraction and an E-ANN based classifier that was evaluated with the Korean finger language (14 consonants, 17 vowels and 7 numbers) in 17 subjects. E-ANN was categorized according to the number of classifiers (1 to 10) and size of training data (50 to 1500). The accuracy of the E-ANN-based classifier was obtained by 5-fold cross validation and compared with an artificial neural network (ANN)-based classifier.</P><P><B>RESULTS AND CONCLUSIONS:</B></P><P> As the number of classifiers (1 to 8) and size of training data (50 to 300) increased, the average accuracy of the E-ANN-based classifier increased and the standard deviation decreased. The optimal E-ANN was composed with eight classifiers and 300 size of training data, and the accuracy of the E-ANN was significantly higher than that of the general ANN.</P>

The improvement of electrical properties of InGaZnO (IGZO)4(IGZO) TFT by treating post-annealing process in different temperatures.

Soonjae Kim,Hoojeong Lee,Heejun Yoo,Gumhee Park,Taewook Kim,Yonghan Roh 한국진공학회 2010 한국진공학회 학술발표회초록집 Vol.39 No.-

Flexible and multi-directional piezoelectric energy harvester for self-powered human motion sensor

Kim, Min-Ook,Pyo, Soonjae,Oh, Yongkeun,Kang, Yunsung,Cho, Kyung-Ho,Choi, Jungwook,Kim, Jongbaeg Institute of Physics Publishing 2018 Smart materials & structures Vol.27 No.3

<P>A flexible piezoelectric strain energy harvester that is responsive to multi-directional input forces produced by various human motions is proposed. The structure of the harvester, which includes a polydimethylsiloxane (PDMS) bump, facilitates the effective conversion of strain energy, produced by input forces applied in random directions, into electrical energy. The structural design of the PDMS bump and frame as well as the slits in the piezoelectric polyvinylidene fluoride (PVDF) film provide mechanical flexibility and enhance the strain induced in the PVDF film under input forces applied at various angles. The amount and direction of the strain induced in PVDF can be changed by the direction of the applied force; thus, the generated output power can be varied. The measured maximum output peak voltage is 1.75, 1.29, and 0.98 V when an input force of 4 N (2 Hz) is applied at angles of 0°, 45°, and 90°, and the corresponding maximum output power is 0.064, 0.026, and 0.02 <I>μ</I>W, respectively. Moreover, the harvester stably generates output voltage over 1.4?×?10<SUP>4</SUP> cycles. Thus, the proposed harvester successfully identifies and converts strain energy produced by multi-directional input forces by various human motions into electrical energy. We demonstrate the potential utility of the proposed flexible energy harvester as a self-powered human motion sensor for wireless healthcare systems.</P>

Sequential microwave roasting and magnetic separation for removal of Fe and Ti impurities in low-grade pyrophyllite ore from Wando mine, South Korea

Kim, Bong-Ju,Cho, Kang Hee,Chang, Bongsu,Kim, Hyun-Soo,Lee, Sang-Gil,Park, Cheon-Young,Lee, Soonjae,Choi, Nag-Choul Elsevier 2019 Minerals engineering Vol.140 No.-

<P><B>Abstract</B></P> <P>The applications and price of pyrophyllite are highly dependent on its Al<SUB>2</SUB>O<SUB>3</SUB> and impurity contents. Titanium as well as iron in pyrophyllite are impurities causing colorization of the final product. We investigated a method for removal of Fe and Ti impurities to improve the grade of pyrophyllite ore using sequential microwave roasting and magnetic separation. Pyrophyllite ore from the Wando mine (South Korea) contains Fe impurities, such as pyrite and hematite, and Ti impurities, such as rutile and Ti-oxides. This research demonstrate that the ore can be purified by the proposed sequential separation technique using microwave treatment and magnetic separation. The purification efficiency for the low-grade pyrophyllite ore was evaluated by conducting batch-scale sequential treatment tests. The microwave treatment magnetized Fe minerals in the ore due to mineral phase changes, and thus the magnetic impurities could be successfully separated by the subsequent magnetic separation. Iron and Ti were removed from the pyrophyllite ore with 86.3% and 68.3% efficiency, respectively, by 30 min of microwave irradiation and 2000 gauss of magnetic separation. The high removal efficiency of Ti impurity was resulted from association of rutile with Fe minerals, although weak. The efficiency of impurity removal was improved by lengthening the microwave irradiation time and increasing the magnetic field intensity. By applying a high magnetic intensity (>5000 gauss), it was possible to remove additional paramagnetic Ti impurities. The sequential separation technique using microwave roasting and magnetic separation may be a promising method for enhancing the grade of low-grade pyrophyllite ore.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low grade pyrophyllite contained impurities, such as pyrite, hematite and rutile. </LI> <LI> Microwave roasting caused Fe impurities gaining magnetic property. </LI> <LI> Magnetized particles were isolated from pyrophyllite ore by magnetic separation. </LI> <LI> Association of Ti mineral with Fe mineral enhanced efficiency of impurity removal. </LI> <LI> Isolated Ti impurities was additionally separated under high magnetic field intensity. </LI> </UL> </P>

An Activation plan of Korea Kimchi distribution Industry in the Chinese Kimchi Market

Soonja Kim,Kihyung Bae,Jae-Eun Lee 한국유통과학회 2018 유통과학연구 Vol.16 No.8

Purpose - To active the Korea kimchi distribution, this study aims to investigate the effect of Korea national image and kimchi image on kimchi purchase intention. this study suggest the strategies for kimchi export to China by examining how the Chinese perceptions of Korean kimchi. Research design, data, and methodology - For this study, empirical analysis was conducted based on survey results. A questionnaire was distributed to a total of 400 Chinese consumers. Of these, 280 were collected and 278 were used for statistical processing, excluding 2 that were found to be unsuitable for analysis. This study was performed by the regression analysis using the spss24 statistical program. Results - As a results, It was not significant that the Chinese consumers’ familiarity on the Korea image will have a positive effect on their kimchi purchase intention. On the other hand, the kimchi/Korean food image of Chinese consumers’ will increase their kimchi consumption experience. Conclusions - The Chinese consumers’ positive image on kimchi/Korean food in terms of the unique characteristics of kimchi, health aspects and preference of kimchi is positively influenced when they have higher image on Korea related to its national characteristics, and that of the higher image for Korea has a positive effect on kimchi purchase intention.

Comparison of Groundwater Modeling under Different Geological Models Constructed from High Resolution Borehole Data

( Mingyeong Kim ),( Jeryeong Kim ),( Minuk Ha ),( Minseo Bae ),( Juhee Kim ),( Ja-young Goo ),( Soonjae Lee ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

High resolution site characterization (HRSC) can support more effective remediation design and faster site cleanup. Recently, researches on HRSC techniques have conducted in Deokso area, Keonggi-do, Korea. In this research, we investigated the groundwater flow under different geological models constructed based on the detailed lithological and structural borehole log from the adjacent boreholes on the test bed. The conceptual hydrogeological models were constructed with homogeneous layer models as well as heterogeneous models. The homogeneous models were derived by interpolating observed contacts in borehole logs. Heterogeneous models were built by geostatistical simulation of lithology variables and material properties using T-PROGS. Over the generated hydrogeology model, the groundwater flow modeling was conducted using MODFLOW. The simulated groundwater flow field in homogeneous layer models were compared with the simulations in a heterogeneous model made with a T-PROGS tool. The simulation results showed that the groundwater flow varied greatly depending on configuration of the conceptual model as well as the resolution of geological survey data.

Optimization of a Pre-impact Fall Detection Algorithm and Development of Hip Protection Airbag System

Ahn, Soonjae,Choi, Dagyeong,Kim, Jongman,Kim, Seongjung,Jeong, Youngjae,Jo, Min,Kim, Youngho MYU K.K. 2018 Sensors and materials Vol.30 No.8

<P>In this study, a pre-impact fall detection algorithm using a custom-made inertial sensor was optimized, and a spring-trigger airbag system was developed for preventing injuries from falls. Four different types of simulated falls were performed by 20 healthy volunteers (age 23.4 +/- 4.4 years), and six different daily activities were tested in 14 elderly subjects (age 71.8 +/- 4.0 years). An inertial sensor unit was used to measure acceleration, angular velocity, and vertical angle during all activities. Thresholds of 0.9 g acceleration, 47.3 degrees/s angular velocity, and 24.7 degrees vertical angle were determined on the basis of optimizing lead time and accuracy in pre-impact fall detection. A belt-type airbag system consisted of a polyurethane inner skin, an artificial leather outer shell, and a spring-trigger inflator. To evaluate the accuracy of the airbag system, 10 healthy adult males (age 28.5 +/- 2.7 years) wore the system and performed three sets of simulated falls. Fall detection was achieved 401.9 +/- 46.9 ms before impact on average, and the airbag inflated without fail during the falls (100% sensitivity). In all daily activities, no airbag inflation occurred (100% specificity).</P>

Application of organic-inorganic hybrid composite particle for removal of heavy metal ions from aqueous solution and its toxicity evaluation

Lee, Soonjae,Kim, Nahae,Cho, Seulki,Ryu, Jae-Chun,Cho, Yoon,Park, Jeong-Ann,Lee, Sang-Hyup,Kim, Juyoung,Choi, Jae-Woo Elsevier 2017 European polymer journal Vol.95 No.-

<P><B>Abstract</B></P> <P>In this study, we present new organic–inorganic (O-I) hybrid composite particles and their possible application asan adsorbent for removal of various inorganic heavy metal from aqueous phase. The O-I hybrid nanoparticles were first prepared by copolymerization of (3-aminopropyl) triethoxysilane (APTES) and alkoxysilane-functionalized amphiphilic polymer (APAS) precursors which have hydrophobic polypropylene oxide segment and hydrophilic polyethylene oxide segment at the same backbones where triethoxysilane groups are chemically bonded with hydrophobic segment. The O-I hybrid composite particles consisting of silica nanoparticles chemically interconnected by O-I hybrid nanoparticles were prepared using the 2nd hydrolysis-condensation reaction. The characteristics of the hybrid particle thus developed were confirmed by FT-IR (Fourier transform infrared) spectroscopy, <SUP>29</SUP>Si-NMR (nuclear magnetic resonance) spectroscopy, EA (Elemental analysis), TGA (thermogravimetric analysis), SEM (scanning electron microscopy), and cryo-TEM (cryogenic transmission electron microscopy). The O-I hybrid particles exhibited removal of cations (Ni, Cu, Zn, Cd and Pb) from aqueous solution with a considerably higher sorption capacity for Pb than for other cations. The heavy metal removal occurred instantaneously with pH increase. A step wise application tests were conducted to distinguish between heavy metal precipitation at a high pH and adsorption by the developed material. Cytotoxicity tests demonstrated that the developed adsorbent has a weak cytotoxic effect on four different types of human cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amphiphilic polymer precursor is conjugated onto silica nanoparticles. </LI> <LI> The composite removed various heavy metal ions from aqueous solution. </LI> <LI> The composite is a promising adsorbent for hydrophilic and/or hydrophobic pollutants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

EM PCB Modeling Oriented RF Co-Simulation Platform for Mobile Handset Applications

Yongsup Kim,Soonjae Kwon,Junseok Yang,Austin Kim 한국통신학회 2007 한국통신학회 학술대회논문집 Vol.2007 No.7