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김민지,신수영,송월섭,조수진,최동락,황미진,황진규,박진현,김경,Dennis W. Fell 대구대학교 특수교육재활과학연구소 2011 再活科學硏究 Vol.29 No.1
이 연구는 트레드밀 운동과 키네시오 테이핑의 효과에 따른 폐활량의 변화를 알아보기 위해 26명의 비흡연자가 참가하였으며 키네시오 테이핑을 적용하지 않은 그룹과 키네시오 테이핑을 적용한 두 그룹으로 무작위로 배정하고 각 군들을 주 3회 6주간의 트레드밀 훈련을 실시하였다. 실험 전과 후, 스파이로미터를 사용하여 키네시오 테이핑의 적용 따른 폐활량 변화 효과를 측정하였다. 이 연구의 결과를 종합해보면 키네시오 테이핑을 적용 그룹에서 적용하지 않은 그룹에 비해 FVC, FEV1에서 유의한 증가를 보였다. 이러한 결과는 건강한 성인에서 키네시오 테이핑을 적용한 경우 키네시오 테이핑을 적용하지 않고 트레드밀 운동을 한 경우보다 폐활량의 향상에 효과적이라고 생각되어진다. The purpose of this study was to investigate the variation of vital capacity(VC) according to the effects of kinesio taping with treadmill exercise. Twenty-six non-smokers were participated in this research and these subjects were randomly assigned into two groups. To measure the VC variation effects of kinesio taping, spirometer was used. The collected data were analyzed statistically by using a paired Mauchly test and repeated measure ANOVA. The results of this study were as follows; A group: treadmill with kinesio taping B group: treadmill without kinesio taping. Between A and B, there were significant differences. In the case of A group, there was 11.66% increase of VC, during 3 weeks experiment(p<.01). In the case of B group, there were significant differences, 3.35% increase of VC, during 3 weeks taping intervention(p<.01). After 6 weeks experiment, the improvement of VC shown a significant difference with intergroup (p<.05). From this result, it was revealed that treadmill exercise with kinesio taping was effective to improve VC to healthy adult than treadmill exercise without kinesio taping.
한민섭,민병권,이상조 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
Electrochemical discharge machining (ECDM)process is one of spark based micromachining methods especially for microstructuring of nonconductive materials such as glass and ceramics. In ECDM process spark discharge is produced by the dielectric gas film which formed by the coalescence of electrochemically generated gas bubbles. ECDM process has been suffered from achieving uniform geometry of microstructures because of the irregular gas film characteristics. In this study various technical approaches, pulse voltage, side insulated electrode and ultrasonic vibrated electrolyte are proposed to improve the geometric accuracy of ECDM process. Side insulated electrode helps improve the spark discharge uniformity by localizing the electrolysis at the tool tip, while ultrasonic vibrated electrolyte enhances the flushing effects at the gap between the tool and the workpiece. Experimental investigation demonstrates that geometric accuracy of microchannel and microhole is improved by using the proposed methods.
Han, Min-Seop,Min, Byung-Kwon,Lee, Sang Jo IOP 2009 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.19 No.6
<P>Electrochemical discharge machining (ECDM) is a spark-based micromachining method especially suitable for the fabrication of various microstructures on nonconductive materials, such as glass and some engineering ceramics. However, since the spark discharge frequency is drastically reduced as the machining depth increases ECDM microhole drilling has confronted difficulty in achieving uniform geometry for machined holes. One of the primary reasons for this is the difficulty of sustaining an adequate electrolyte flow in the narrow gap between the tool and the workpiece, which results in a widened taper at the hole entrance, as well as a significant reduction of the machining depth. In this paper, ultrasonic electrolyte vibration was used to enhance the machining depth of the ECDM drilling process by assuring an adequate electrolyte flow, thus helping to maintain consistent spark generation. Moreover, the stability of the gas film formation, as well as the surface quality of the hole entrance, was improved with the aid of a side-insulated electrode and a pulse-power generator. The side-insulated electrode prevented stray electrolysis and concentrated the spark discharge at the tool tip, while the pulse voltage reduced thermal damage to the workpiece surface by introducing a periodic pulse-off time. Microholes were fabricated in order to investigate the effects of ultrasonic assistance on the overcut and machining depth of the holes. The experimental results demonstrated that the possibility of consistent spark generation and the machinability of microholes were simultaneously enhanced.</P>
One-step etching, doping, and adhesion-control process for graphene electrodes
Jo, Kyungmin,Kim, Sang-Min,Lee, Seung-Mo,Kim, Jae-Hyun,Lee, Hak-Joo,Kim, Ki Soo,Kwon, Yong Duck,Kim, Kwang-Seop Elsevier 2015 Carbon Vol.82 No.-
<P><B>Abstract</B></P> <P>Enhancing the electrical conductivity and reliability of graphene electrodes is critical for the practical realization of graphene-based electronics, since these factors influence the electrical performance of devices. To achieve such improvements in graphene electrodes requires additional processes such as doping and surface treatments, which inevitably complicate device fabrication. Here, we introduce a novel, straightforward one-step etching method, in which a catalytic copper substrate is etched in imidazole-containing ammonium persulfate solution, of simultaneously enhancing the electrical and adhesion properties of graphene grown on copper foil by chemical vapor deposition. Applying one-step etching method, the sheet resistance of monolayer graphene with 270Ω/sq is obtained, while the adhesion of graphene is improved by 20%. Moreover, the electrical conductivity of graphene remained improved after storage for 30days in ambient conditions without any passivation layers, and the graphene was almost transparent with transmittance of 97.7% at 550nm. The enhancement of the electrical and adhesion properties of graphene originated from the synergistic adsorption of imidazole and etched Cu ions, which results in p-doping of graphene.</P>
Jo, Kyungmin,Lee, Sangbong,Kim, Sang-Min,In, Jung Bin,Lee, Seung-Mo,Kim, Jae-Hyun,Lee, Hak-Joo,Kim, Kwang-Seop American Chemical Society 2015 Chemistry of materials Vol.27 No.10
<P>Fabrication of a transparent and flexible supercapacitor requires electrode materials that are optically transparent and mechanically flexible. Although chemical vapor deposition (CVD)-grown graphene is a promising electrode material, its use in supercapacitor applications is greatly limited by the low area-specific capacitance of the fabricated supercapacitor. Here, we demonstrate transparent and flexible high-performance supercapacitor using stacked bilayer graphene and an ultrathin redox-active interlayer. By inserting the redox-active layer between stacked bilayer graphene, we achieved an almost 20-fold enhancement of the area-specific capacitance (from 5.6 μF/cm<SUP>2</SUP> to 101 μF/cm<SUP>2</SUP>) with a thickness of electrode material for each electrode less than 2 nm. In addition, the fabricated supercapacitor exhibited excellent transparency of 75% (including the substrate’s transparency) and flexibility (bending radius down to 5 mm) by virtue of the outstanding transparency and flexibility of the stacked bilayer graphene and redox-active interlayer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-10/cm504801r/production/images/medium/cm-2014-04801r_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm504801r'>ACS Electronic Supporting Info</A></P>
Min Ji Jang,Hyunjeong Kwak,Ye Won Lee,Youjin Jeong,Jahong Choi,Yong Hee Jo,Won-Mi Choi,Hyun Je Sung,Eun Yoo Yoon,S. Praveen,Sunghak Lee,Byeong-Joo Lee,Mohamed Ibrahim Abd El Aal,Hyoung Seop Kim 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2
A single FCC phase 40Fe–25Ni–15Cr–10Co–10V high-entropy alloy was designed, fabricated, and evaluated for potentialcryogenic applications. The alloy forms a single FCC phase and exhibits higher yield strength, tensile strength, and elongationat cryogenic temperature (77 K) than at room temperature (298 K). The superior tensile properties at cryogenic temperatureare discussed based on the formation of deformation twins during the tensile test at cryogenic temperature. In addition, aconstitutive model reflecting the cryogenic deformation mechanism (i.e., twinning-induced plasticity) was implementedinto the finite element method to analyze this behavior. Experimental results and the finite element analysis suggest that theincrease in plastic deformation capacity at cryogenic temperature contributes to the formation of deformation twins.
Purification of Si using Catalytic CVD
조철기(Jo, Chul-Gi),이경섭(Lee, Kyeong-Seop),송민우(Song, Min-Wu),김영순(Kim, Young-Soon),신형식(Shin, Hyung-Shik) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.11
Silicon is commercially prepared by the reaction of high-purity silica with wood, charcoal, and coal, in an electric arc furnace using carbon electrodes, so called the metallurgical refining process, which produces ~98% pure Si (MG-Si). This can be further purified to solar grade silicon (SoG-Si) by various techniques. The most problematic impurity elements are B and P because of their high segregation coefficients. In this study, we explored the possibility of the using Cat-CVD for Si purification. The existing hot-wire CVD was modified to accommodate the catalyzer and the heating source. Mo boat (1.5 cm {times} 1 cm {times} 0.2 cm) was used as a heating source. Commercially available Si was purchased from Nilaco corporation (~99% pure). This powder was kept in the Mo-boat and heated to the purification temperature. In addition to the purification by cat-CVD technique, other methods such as thermal CVD, plasma enhanced CVD, vacuum annealing was also tried. It is found that the impurities are reduced to a great extent when treated with cat-CVD method.