• 재활복지
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• v.21 no.3
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• pp.147-163
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• 2017

The purpose of this study was to examine how horse-riding exercise would be effective on the stroke patients' muscle thickness of lower extremity. The 30 stroke patients who were hospitalized in a hospital located in G metropolitan city were selected for this study. These subjects were randomly placed in a horse-riding exercise group (n=15) and a control group (n=15). The horse-riding exercise group received three 20-minute exercises a week for a total of 6 weeks. An ultrasound imaging equipment was used to measured The thicknesses of the rectus femoris (RF), tibialis anterior (TA), medial gastrocnemius (MG), and gluteus medius (GM). After the completion of a 6-week exercise program, same measurement was conducted for all study subjects. The data were analyzed using a paired t-test and independent t-test to determine the statistical significance. As a result, muscle thickness was significantly differentiated before and after the intervention in each group. The thicknesses of all the four muscles significantly increased after exercise in the horse-riding exercise group. The thicknesses of the RF, GM, and TA significantly increased after exercise in the control group. In conclusion, horse-riding exercise increased the thickness of the lower extremity skeletal muscles by stabilizing the knees and activating the extensor muscles of the lower extremities.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.382.1-382.1
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• 2014

Graphene field-effect transistors (GFET) is one of candidates for future high speed electronic devices since graphene has unique electronic properties such as high Fermi velocity (vf=10^6 m/s) and carrier mobility ($15,000cm^2/V{\cdot}s$) [1]. Although the contact property between graphene and metals is a crucial element to design high performance electronic devices, it has not been clearly identified. Therefore, we need to understand characteristics of graphene/metal contact in the GFET. Recently, it is theoretically known that graphene on metal can be doped by presence of interface dipole layer induced by charge transfer [2]. It notes that doping type of graphene under metal is determined by difference of work function between graphene and metal. In this study, we present the GFET fabricated by contact metals having high work function (Pt, Ni) for p-doping and low work function (Ta, Cr) for n-doping. The results show that asymmetric conductance depends on work function of metal because the interfacial dipole is locally formed between metal electrodes and graphene. It induces p-n-p or n-p-n junction in the channel of the GFET when gate bias is applied. In addition, we confirm that charge transfer regions are differently affected by gate electric field along gate length.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.90-97
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• 2007

8-Hydroxyquinoline is used as antibacterial agent and antioxidant based on its function inducing the chelation of ferrous ion present in host resulting in production of chelated complex. This complex being transported to cell membrane of bacteria and fungi exerts antibacterial and antifungal action. In this study, we have carried out in vitro genetic toxicity tests and microarray analysis to understand the underlying mechanisms and the mode of action of toxicity of 8-hydroxyquinoline. TA1535 and TA98 cells were treated with 8-hydroxyquinoline to test its toxicity by basic genetic toxicity test, Ames and two new in vitro micronucleus and COMET assays were applied using CHO cells and L5178Y cells, respectively. In addition, microarray analysis of differentially expressed genes in L5178Y cells in response to 8-hydroxyquinoline were analyzed using Affymatrix genechip. The result of Ames test was that 8-hydroxyquinoline treatment increased the mutations in base substitution strain TA1535 and likewise, 8-hydroxyquinoline also increased mutations in frame shift TA98. 8-Hydroxyquinoline increased micronuclei in CHO cells and DNA damage in L5178Y. 8-Hdroxyquinoline resulted in positive response in all three tests showing its ability to induce not only mutation but also DNA damage. 783 Genes were initially selected as differentially expressed genes in response to 8-hydroxyquinoline by microarray analysis and 34 genes among them were over 4 times of log fold changed. These 34 genes could be candidate biomarkers of genetic toxic action of 8-hydroxyquinoline related to induction of mutation and/or induction of micronuclei and DNA damage. Further confirmation of these candidate markers related to their biological function will be useful to understand the detailed mode of action of 8-hydroxyquinoline.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.62-62
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• 2003

금속-실리콘간 화합물인 실리사이드 중에서, 코발트다이실리사이드(CoSi$_2$)는 비저항이 낮고 선폭이 좁아짐에 따라 면저항이 급격히 증가하는 선폭의존성이 없으며 화학적으로 안정한 재료로 현재 널리 이용되고 있는 재료이다. 또한, 실리콘 (100) 기판과 에피택셜하게 성장한 CoSi$_2$는 우수한 열안정성 과 낮은 juction leakage의 특성을 가지며, shallow junction 형성을 가능하게 하는 많은 장점을 가지고 있어 각광받고 있다. 그러나 순수한 Co의 증착 후속 열처리에 의해 형성된 CoSi$_2$는 (110), (111), (221)등의 다양한 결정방위를 가지게 되어 에피택셜 하게 형성되기 어렵다. 현재까지 Ti, Ta, Zr과 화학 산화막 등의 확산 방지막을 이용하여 에피 택셜하게 성장시키는 많은 방법들이 연구되어 왔으며, 최근에는 본 연구실에서 반응성화학기상증착법으로 Co-C 박막을 증착하여 in-Situ로 에피택셜 CoSi$_2$를 형성하는 새로운 방법을 보고하였다. 본 연구는 반응성 스퍼터링에 의해 증착된 Co-N 박박으로부터 후속 열처리를 통하여 에피택셜 CoSi$_2$를 성장시키는 새로운 방법을 제시하고자 한다. Co-N 박박은 Ar과 $N_2$의 혼합가스 분위기 속에서 Co를 스퍼터링하여 증착하였다. 증착시 혼합가스 내의 $N_2$함량의 변화에 따라 다양한 Co-N 박막이 형성됨을 확인하였다. 후속열처리시 Co-N 박막의 산화를 방지하기 위하여 Ti층을 마그네트론 스퍼터링으로 증착하였으며, Ar 분위기에서 온도에 따른 ex-situ RTA 열처리를 통하여 에피택셜 CoSi$_2$를 성장시킬 수 있었다. 이러한 에피택셜 CoSi$_2$는 특정 한 Ar/$N_2$ 비율 내에서 성장이 가능하였으며, 약 $600^{\circ}C$이상의 열처리 온도에서 관찰되었다.

• The Korean Journal of Ecology
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• v.27 no.3
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• pp.155-159
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• 2004

In order to gain a better understanding of how forests participate in the cycling of carbon, effects of nitrogen addition on soil respiration were investigated on the oak forest in Kongju, Korea. Study site was divided into control, treatment f and treatment 2 plots, with 5 replication in each plot. In each replicate of treatment 1 and treatment 2 were fertilized with ammonium nitrate (NH$_4$NO$_3$), 30 g/$m^2$ and 60 g/$m^2$, respectively. Soil respiration, soil temperature, ammonium-N and nitrate-N were measured during the experimental period. Ammonium-N and nitrate-N in Ta were higher than those in control and T$_1$. Ammonium-N and nitrate-N in top-soil and sub-soil decreased sharply in August after bi9 rainfall in July in T$_1$ and T$_2$, however, those in control plot increased. Soil respiration in T$_2$ Plot showed consistently higher than those in control and T$_1$ until the end of July. However, soil respiration was similar among the control, T$_1$ and T$_2$ in mid-August and September The amount of Co$_2$ released from soil respiration in control, T$_1$ and T$_2$ in mid-August was 8.0$\pm$0.4, 9.3$\pm$0.6 and 10.2$\pm$0.5 $\mu$mol$^{-1}$ ㆍm$^{-2}$ ㆍs$^{-1}$ , respectively. However, those in control, T$_1$ and T$_2$in mid-August was 13.0$\pm$0.4, 13.5$\pm$0.5, 13.3$\pm$0.6 $\mu$mol$^{-1}$ ㆍm$^{-2}$ ㆍ$^{-1}$ , respectively. The results suggest that nitrogen addition in this oak forest has a positive effect on soil respiration.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.111-112
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• 2009

Diamond-like carbon (DLC) is a convenient term to indicate the compositions of the various forms of amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), hydrogenated amorphous carbon and tetrahedral amorphous carbon (a-C:H and ta-C:H). The a-C film with disordered graphitic ordering, such as soot, chars, glassy carbon, and evaporated a-C, is shown in the lower left hand corner. If the fraction of sp3 bonding reaches a high degree, such an a-C is denoted as tetrahedral amorphous carbon (ta-C), in order to distinguish it from sp2 a-C [2]. Two hydrocarbon polymers, that is, polyethylene (CH2)n and polyacetylene (CH)n, define the limits of the triangle in the right hand corner beyond which interconnecting C-C networks do not form, and only strait-chain molecules are formed. The DLC films, i.e. a-C, ta-C, a-C:H and ta-C:H, have some extreme properties similar to diamond, such as hardness, elastic modulus and chemical inertness. These films are great advantages for many applications. One of the most important applications of the carbon-based films is the coating for magnetic hard disk recording. The second successful application is wear protective and antireflective films for IR windows. The third application is wear protection of bearings and sliding friction parts. The fourth is precision gages for the automotive industry. Recently, exciting ongoing study [1] tries to deposit a carbon-based protective film on engine parts (e.g. engine cylinders and pistons) taking into account not only low friction and wear, but also self lubricating properties. Reduction of the oil consumption is expected. Currently, for an additional application field, the carbon-based films are extensively studied as excellent candidates for biocompatible films on biomedical implants. The carbon-based films consist of carbon, hydrogen and nitrogen, which are biologically harmless as well as the main elements of human body. Some in vitro and limited in vivo studies on the biological effects of carbon-based films have been studied [$2{\sim}5$].The carbon-based films have great potentials in many fields. However, a few technological issues for carbon-based film are still needed to be studied to improve the applicability. Aisenberg and Chabot [3] firstly prepared an amorphous carbon film on substrates remained at room temperature using a beam of carbon ions produced using argon plasma. Spencer et al. [4] had subsequently developed this field. Many deposition techniques for DLC films have been developed to increase the fraction of sp3 bonding in the films. The a-C films have been prepared by a variety of deposition methods such as ion plating, DC or RF sputtering, RF or DC plasma enhanced chemical vapor deposition (PECVD), electron cyclotron resonance chemical vapor deposition (ECR-CVD), ion implantation, ablation, pulsed laser deposition and cathodic arc deposition, from a variety of carbon target or gaseous sources materials [5]. Sputtering is the most common deposition method for a-C film. Deposited films by these plasma methods, such as plasma enhanced chemical vapor deposition (PECVD) [6], are ranged into the interior of the triangle. Application fields of DLC films investigated from papers. Many papers purposed to apply for tribology due to the carbon-based films of low friction and wear resistance. Figure 1 shows the percentage of DLC research interest for application field. The biggest portion is tribology field. It is occupied 57%. Second, biomedical field hold 14%. Nowadays, biomedical field is took notice in many countries and significantly increased the research papers. DLC films actually applied to many industries in 2005 as shown figure 2. The most applied fields are mold and machinery industries. It took over 50%. The automobile industry is more and more increase application parts. In the near future, automobile industry is expected a big market for DLC coating. Figure 1 Research interests of carbon-based filmsFigure 2 Demand ratio of DLC coating for industry in 2005. In this presentation, I will introduce a trend of carbon-based coating research and applications.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.243-248
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• 2012

ZrN nanoparticles were prepared by an exothermic reduction of $ZrCl_4$ with $NaN_3$ in the presence of NaCl flux in a nitrogen atmosphere. Using a solid-state combustion approach, we have demonstrated that the zirconium nitride nanoparticles synthesis process can be completed in only several minutes compared with a few hours for previous synthesis approaches. The chemistry of the combustion process is not complex and is based on a metathesis reaction between $ZrCl_4$ and $NaN_3$. Because of the low melting and boiling points of the raw materials it was possible to synthesize the ZrN phase at low combustion temperatures. It was shown that the combustion temperature and the size of the particles can be readily controlled by tuning the concentration of the NaCl flux. The results show that an increase in the NaCl concentration (from 2 to 13 M) results in a temperature decrease from 1280 to $750^{\circ}C$. ZrN nanoparticles have a high surface area (50-70 $m^2/g$), narrow pore size distribution, and nano-particle size between 10 and 30 nm. The activation energy, which can be extracted from the experimental combustion temperature data, is: E = 20 kcal/mol. The method reported here is self-sustaining, rapid, and can be scaled up for a large scale production of a transition metal nitride nanoparticle system (TiN, TaN, HfN, etc.) with suitable halide salts and alkali metal azide.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.1
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• pp.69-76
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• 2008

Objective: The purposes of this study were to determine the distribution of follicle-stimulating hormone receptor (FSHR) genotypes in infertile Korean women and to evaluate the relationship between FSHR genotypes and clinical outcomes of IVF-ET cycles. Methods: Genomic DNA was extracted from peripheral blood in 1, 020 of infertile Korean women. Genotypes of FSHR at Thr307Ala (T/A) and Asn680Ser (N/S) were screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Clinical outcomes related to the genotypes of FSHR were evaluated in IVF-ET cycles (n=302) with controlled ovarian hyperstimulation (COH) of infertile women under 40 years old. Results: In a population of 1, 020 infertile Korean women, the frequency of TT/NN, TA/NS and AA/SS for the major variant Thr307Ala and Asn680Ser was 44.80%, 41.96% and 10.49%, respectively. There was no significant difference in characteristics of ovarian response and clinical pregnancy rate among the major genotypes of FSHR in IVF-ET cycles with COH. However, implantation rate of AA/SS patients was significantly higher than that of TT/NN patients (24.5% vs 15.7%, p<0.05). Conclusion: This study showed that FSHR genotype was not directly associated with ovarian response in IVF-ET cycles with COH. The relationship between clinical outcomes and FSHR genotypes of patients should be substantiated by further studies.

• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.19-33
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• 1997

This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.297-300
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• 2012

In the present study, we investigated and compared the oxidant-antioxidant status of dogs undergoing open and laparoscopic cholecystectomy. Ten male beagle dogs, 4-6 years old, weighing 7-12 kg were used. The animals were randomly assigned to one of two groups according to the type of surgical procedure; open (group 1, n = 5) or laparoscopic cholecystectomy (group 2, n = 5). Heart rate, mean arterial pressure, end-tidal carbon dioxide, peripheral oxygen saturation, and respiratory rates were measured. Plasma total oxidant status (TOS) and total antioxidant status (TAS) levels for the evaluation of oxidative stress were measured. The ratio of the TOS to the TAS gave oxidative stress index (OSI), which is an indicator of the degree of oxidative stress. TOS, OSI and TAS levels were significantly changed after surgery in comparison to levels of before anesthesia. There were no significant different between groups. In the present study, we showed that oxidative stress parameters were found similar in dogs underwent laparoscopic or open cholecystectomy.