Enhanced thermal conductivity of polymer composites in a hybrid filler system

하성민,이횡래,조광수,유영재,원종찬,이성구 한국고분자학회 2012 한국고분자학회 학술대회 연구논문 초록집 Vol.2012 No.10

Thermally conductive PI/h-BN nanocomposite films with high anisotropy

하성민,권오환,김병각,김용석,원종찬,유영재 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.4

Isolated Activation of the Upper Trapezius in Three Manual Muscle Testing Position : Convergence Study

하성민 한국융합학회 2020 한국융합학회논문지 Vol.11 No.1

The purpose of this study was to investigate the optimal position among three manual muscle tested positions for upper trapezius in which to obtain an isolated upper trapezius EMG signal for the normalization of upper trapezius muscle EMG activity. A total of 28 healthy adult men participated in the experiment. The UT (upper trapezius) and LS (levator scapulae) muscle activities were measured using the TeleMyo 2400T and analyzed using MyoResearch software. The muscle activity of the US and LS was measured by performing three manual muscle test positions for the upper trapezius. The UT/LS ratio during the S-MVIC was 80.25 and was significantly higher than that during the T-MVIC (76.50; p = 0.011) and the C-MVIC (60.95; p < 0.001). And, the UT/LS ratio during the T-MVIC and was significantly higher than that during the C-MVIC (p < 0.001). Based on the results of present study, we suggest a switch from T-MVIC to S-MVIC for the independent normalization reliability of upper trapezius EMG activity. The UT muscle strength or normalization test using S-MVIC will be able to measure muscle strength or activity of UT compared to previous measurement methods.

Thermally conductive polyamide 6/carbon fillers composites based on hybrid filler system

하성민,이횡래,유영재,조광수,원종찬,이성구 한국고분자학회 2013 한국고분자학회 학술대회 연구논문 초록집 Vol.2013 No.10

A Study on the Perception of Learning Coaches about Dyslexia

하성민,최진오,정종성 (사)위기관리이론과실천 2022 Journal of Safety and Crisis Management Vol.12 No.12

The purpose of this study was to examine the perceptions about dyslexia of the learning coaches working at the basic education support center, and to identify what personal variables affected those perceptions. In K-Province, 122 learning coaches at 7 centers were surveyed about their perceptions of the causes, symptoms, diagnosis, and treatment of dyslexia. Descriptive statistics and a regression analysis were used to examine the accuracy level of learning coaches' perceptions of dyslexia, and what individual variables affected those accuracy level. The results showed that learning coaches had an inaccurate perception of the cause, diagnosis, and treatment of dyslexia, except for the symptoms of dyslexia (correct answer rate of 58.2%). Second, among the individual variables of learning coaches, teaching experience, training experience, and course completion about dyslexia had a positive effect on their perceptions of dyslexia, while self-confidence in teaching students with dyslexia had a negative effect on their perceptions. The results of this study also indicated that training about dyslexia for learning coaches should be continuously provided because the training experience had the most positive effects on their accurate perceptions of dyslexia.

침전법을 이용한 YAG분말의 합성 및 소결

하성민,이재홍,박준영,심수만 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.3

Al 및 Y 질산염 용액에 탄산수소암모늄(NH$_4$HCO$_3$)을 침전제로 사용하여 YAG 분말을 합성하였다. 침전물을 attrition-milling한 결과, $Y_2$O$_3$와 YAG 상이 생성되었으며, 분쇄한 침전물을 110$0^{\circ}C$에서 1시간 하소하여 결정상이 잘 발달된 YAG 단일상 분말을 얻을 수 있었다. 분말의 소결성은 소결조제 SiO$_2$(500ppm Si)의 첨가에 관계없이 매우 우수하였다. 모든 시편은 130$0^{\circ}C$에서 이미 70% 이상의 밀도로 소결되었으며,140$0^{\circ}C$에서도 -83%의 밀도를 나타내었다. SiO$_2$로 도핑한 시편은 도핑하지 않은 시편 보다 치밀화가 약간 향상되었으며, 1$600^{\circ}C$에서 97%의 소결밀도가 얻어졌다. Yttrium Aluminum Garnet (YAG) powders were synthesized by precipitation of solutions of Al and Y nitrates using ammonium hydrogen carbonate as a precipitant. Y$_2$O$_3$ and YAG phases were formed in the precipitates, which had been attrition-milled. Well-crystallized, phase-pure YAG powders were obtained after calcination of the milled precipitates at 1100$^{\circ}C$ for 1 h. The powders were found to exhibit an excellent sinterability regardless of the addition of SiO$_2$(500 ppm Si) as a sintering aid. All samples already densified to relative densities greater than 70% at 1300$^{\circ}C$ and relative densities of ∼83% at 1400$^{\circ}C$. The samples doped with SiO$_2$ showed a little improvement in densification as compared with those for the undoped samples and resulted in a relative density of 97% at 1600$^{\circ}C$.

Multiple performance enhancements with one effect: Improving the electrochemical performance of SiOx coated with specific aromatic compounds

하성민,황기범,김대섭,윤송훈,이영석 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

In this study, modification is performed with pyrolyzed fuel oil to analyze the constituent components ofpetroleum residue oil (PRO), and carbon coating are performed on SiOx surfaces through vapor depositionto determine the effects of the aromatic compounds from the PRO. The effects of the carbon-coating fromPRO on the electrochemical performance of a lithium-ion battery are also examined. Carbon-coating layerswith amorphous structures and thicknesses of 13.8 to 24.6 nm are obtained depending on the depositiontemperature. After 50cycles, the coulombic efficiency of the sample is 99.8 %, the initial cyclecapacity is 1095.4 mAh/g at a current density of 1.0C. The rate test results for this sample showing acapacity of 417.4 mAh/g at a current density of 2.0C. This is attributing to the formation of a thickcarbon-coating layer on the sample’s surface, which maintaining the stability of the sample’s structureand suppressing volume expansion. The impedance of this sample also shows the lowest resistance at189.2 X, indicating a better electrochemical performance compared to those of the others. Since 250PRO contains more 2,3-cycle aromatic compounds than other samples, it is much easier to form thepoly-aromatic compound when forming the carbon coating layer of SiOx, thereby improving electricalconductivity and lithium ion diffusion.

Improving Energy & Power density of Li/CF_X primary battery through control of C-F bonds using a thermobaric modification

하성민,임채훈,민충기,하나은,이영석 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.1

Selective Activation of Thoracic Extensor Muscles during 3 Different Trunk Extensor Strengthening Exercise

하성민,정성훈,김준희,곽경태 KEMA학회 2017 근골격계과학기술학회 Vol.1 No.1

ABSTRACT Background Although there are many exercises to selectively strengthen the thoracic extensor, general trunk extensor strengthening exercises lead to pain and excessive lumbar extension. Purpose We investigated the most effective exercise among three thoracic extensor strengthening exercises (active prone thoracic extension, active prone thoracic hyper-extension, and active sitting thoracic extension) based on selective activity of the thoracic spine extensors. Study design Comparative, repeated measures design. Methods Sixteen healthy participants performed three thoracic extensor strengthening exercises. Electromyograph (EMG) activity was measured in the longissimus thoracis (LT), iliocostalis thoracis (ICT), and iliocostalis lumborum (ICL) muscles. Results The ICT/ICL and LT/ICL composition ratios were greatest in active sitting thoracic extension compared to other exercises. Conclusions We recommend active sitting thoracic extension exercise for selective strengthening of the thoracic spine extensor. ABSTRACT Background Although there are many exercises to selectively strengthen the thoracic extensor, general trunk extensor strengthening exercises lead to pain and excessive lumbar extension. Purpose We investigated the most effective exercise among three thoracic extensor strengthening exercises (active prone thoracic extension, active prone thoracic hyper-extension, and active sitting thoracic extension) based on selective activity of the thoracic spine extensors. Study design Comparative, repeated measures design. Methods Sixteen healthy participants performed three thoracic extensor strengthening exercises. Electromyograph (EMG) activity was measured in the longissimus thoracis (LT), iliocostalis thoracis (ICT), and iliocostalis lumborum (ICL) muscles. Results The ICT/ICL and LT/ICL composition ratios were greatest in active sitting thoracic extension compared to other exercises. Conclusions We recommend active sitting thoracic extension exercise for selective strengthening of the thoracic spine extensor.

무선랜용 I/Q 채널 12bit 120MHz CMOS D/A 변환기 설계

하성민,윤광섭,남태규,서성욱,신선화,주찬양 대한전자공학회 2006 電子工學會論文誌-SD (Semiconductor and devices) Vol.43 No.11

This paper describes the design of I/Q channel 12bit Digital-to-Analog Converter(DAC) which shows the conversion rate of 120MHz and the power supply of 3.3V with 0.35um CMOS n-well 1-poly 4-metal process for advanced wireless transceiver. The proposed DAC utilizes 4-bit thermometer decoder with 3 stages for minimum glitch energy and linearity error. Also, using a optimized 4bit thermometer decoder for the decrement of the chip area. Integral nonlinearity(INL) of ±1.6LSB and differential nonlinearity(DNL) of ±1.3LSB have been measured. In single tone test, the ENOB of the proposed 12bit DAC is 10.5bit and SFDR of 73dB(@ Fs=120MHz, Fin=1MHz) is measured, respectively. Dual-tone test SFDR is 61 dB (@ Fs=100MHz, Fin=1.5MHz, 2MHz). Glitch energy of 31 pV·s is measured. The converter consumes a total of 105mW from 3.3-V power supply. 본 논문에서는 무선통신용 송수신기에 집적화할 수 있도록 0.35μm CMOS n-well 1-poly 4-metal 공정을 이용하여 3.3V의 전원 전압으로 동작하는 I/Q 채널 12비트 120MHz 전류구동 D/A 변환기를 설계하였다. 설계된 12비트 D/A 변환기는 4비트 온도계 디코더를 3단 구성하여 글리치 에너지와 선형오차 특성을 최소화 하였다. 측정된 선형오차인 INL/DNL은 각각 ±1.5 LSB, ±1.3LSB이며, 글리치 에너지는 31pV·s 로 측정되었고, 전력소모는 105mW이다. 샘플링 및 입력주파수가 각각 120MHz, 1MHz일 때, 싱글 톤 테스트에서 유효비트수는 10.5비트로 측정되었다. 듀얼 톤 테스트에서 1MHz/1.1MHz 의 기저대역신호는 0.9MHz/1.2MHz의 영상신호 차이가 -63dB 나타나는 것으로 측정되었다.