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        검색결과 606

        101.
        2018.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        W-10 wt% Ti alloys that have a homogeneous microstructure are prepared by thermal decomposition of WO3-TiH2 powder mixtures and spark plasma sintering. The reduction and dehydrogenation behavior of WO3 and TiH2 are analyzed by temperature programmed reduction and a thermogravimetric method, respectively. The X-ray diffraction analysis of the powder mixture, heat-treated in an argon atmosphere, shows W- oxides and TiO2 peaks. Conversely, the powder mixtures heated in a hydrogen atmosphere are composed of W, WO2 and TiO2 phases at 600 ℃ and W and W-rich β phases at 800 ℃. The densified specimen by spark plasma sintering at 1500 ℃ in a vacuum using hydrogen-reduced WO3-TiH2 powder mixtures shows a Vickers hardness value of 4.6 GPa and a homogeneous microstructure with pure W, β and Ti phases. The phase evolution dependent on the atmosphere and temperature is explained by the thermal decomposition and reaction behavior of WO3 and TiH2.
        4,000원
        102.
        2018.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A citric acid functionalized graphene oxide nanocomposite was successfully synthesized and the structure and morphology of the nanocatalyst were comprehensively characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, X-ray diffraction patterns, atomic force microscopy images, scanning electron microscopy images, transmission electron microscopy images, and thermogravimetric analysis. The application of this nanocatalyst was exemplified in an important condensation reaction to give imidazole derivatives in high yields and short reaction times at room temperature. The catalyst shows high catalytic activity and could be reused after simple work up and easy purification for at least six cycles without significant loss of activity, which indicates efficient immobilizing of citrate groups on the surface of graphene oxide sheets.
        4,000원
        108.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spherical monosized pure aluminum (Al) particles are successfully fabricated by the pulsated orifice ejection method (POEM). The surface reaction between Al and the graphite crucible is investigated by analysing the microstructure and chemical composition of the materials. No significant chemical reaction occurs between Al and the graphite owing to the crystalline Al oxide (γ-Al2O3) layer generated in the initial state. The γ-Al2O3 layer is clearly observed in all regions between the Al particles and graphite via transmission electron microscopy and confirmed by the selected area diffraction pattern. The morphology of the γ-Al2O3 layer perfectly follows the surface morphology of the graphite crucible, which showed nanoscale roughness. This implies that molten Al could not directly contact graphite even though the surface of the crucible became rough to some extent. However, this passivation phenomenon allowed the successful fabrication of monosized pure Al particles. Therefore, POEM is a useful process at least to manufacture monosized pure Al particles.
        4,000원
        109.
        2018.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nitrogen (N)-doped protein-based carbon as platinum (Pt) catalyst supports from tofu for oxygen reduction reactions are synthesized using a carbonization and reduction method. We successfully prepare 5 wt% Pt@N-doped protein-based carbon, 10 wt% Pt@N-doped protein-based carbon, and 20 wt% Pt@N-doped protein-based carbon. The morphology and structure of the samples are characterized by field emission scanning electron microscopy and transmission electron micro scopy, and crystllinities and chemical bonding are identified using X-ray diffraction and X-ray photoelectron spectroscopy. The oxygen reduction reaction are measured using a linear sweep voltammogram and cyclic voltammetry. Among the samples, 10 wt% Pt@N-doped protein-based carbon exhibits exellent electrochemical performance with a high onset potential of 0.62 V, a high E1/2 of 0.55 V, and a low ΔE1/2= 0.32 mV. Specifically, as compared to the commercial Pt/C, the 10 wt% Pt@N-doped proteinbased carbon had a similar oxygen reduction reaction perfomance and improved electrochemical stability.
        4,000원
        110.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        산업과 의학이 발전되면서 많은 인구는 삶의 질에 관심을 가지게 되었다. 건강에 대한 시각이 높아지면서 육류보다 채식 또는 식물성 오일을 선호하게 되었다. 오늘날 주로 니켈 촉매를 사용한 공정이 개발되면서 식물성 오일의 보존기간이 늘어나고 이동성이 편리해졌다. 현재 유지경화용 니켈 촉매는 외국기업이 세계시장을 장악하고 있다. 한편, 국내 니켈 촉매의 대량 생산 기술은 퇴보 되어 전량 외국에서 수입하고 있는 실정이다. 따라서 활발한 기초연구가 필요하고 국내에서 상용화 할 수 있는 촉매개발이 필요하다. 본 연구는 수소화 반응으로부터 유지경화에 기반이 되는 니켈을 주 활성 촉매제로 사용하였고, 희토류가 촉매의 활성에 주는 영향을 알아보았다. 일정량의 희토류는 니켈의 분산을 유도하여 효율을 증가시키고 조촉매로써 사용이 가능하였다.
        4,000원
        111.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 전체산업에서 차지하는 서비스분야의 비중이 높아짐에 따라 자신이 실제 느끼는 감정과는 다른 표현을 하며 일해야 하는 감정노동자들의 고충이 사회적 이슈로 부각되고 있다. 이러한 감정노동자들은 고객들에게 심한 모욕과 비인격적인 대우를 받아도 조직이 정한 감정규칙을 준수하여 항상 친절한 응대 와 태도를 유지하도록 요구받고 있다. 이로 인해 감정노동자들은 심한 심리적 불안과 스트레스에 직면하고 있으며 이는 각종 질환에 노출되게 한다. 이러한 상황에서 감정노동자들의 직무불만족으로 인해 이직률이 증가하고 있는 실정이다. 이에 본 연구에서는 서비스 종사원의 감정노동전략을 표면행동과 내면행동으로 구분하여 감정부조화에 미치는 영향을 살펴보고, 감정부조화가 직무불만족에 미치는 영향과 직무 불만족이 파괴적인 반응행동인 태만행동과 이탈행동에 미치는 영향을 살펴보고자 한다. 또한 감정표현규칙 몰입이 감정노동과 감정부조화의 관계를 어떻게 조절하는지를 살펴보고자 한다. 이를 위해 서비스업에 종사하는 감정노동자들을 대상으로 설문조사를 실시하였으며 총 380부의 설문지가 배포되었고, 불성실한 응답을 제외한 377부의 설문지가 분석에 활용되었다. 실증분석 결과는 다음과 같다. 첫째, 표면행동은 감정부조화에 정(+)의 유의적인 영향을 미치고 내면행동은 감정부조화에 부(-)의 유의적인 영향을 미치는 것으로 나타났다. 둘째, 감정부조화는 직무불만족에 정(+)의 유의적인 영향을 미치며 셋째, 직무불만족은 태만행동과 이탈행동에 모두 정(+)의 유의적인 영향을 미치는 것으로 나타났다. 넷째, 감정노동이 감정부조화와 직무불만족을 이중매개로 태만행동과 이탈행동에 영향을 미치고 있음이 확인되었다. 마지막으로, 감정표현규칙 몰입이 높을수록 내면행동은 감정부조화에 미치는 효과가 유의하게 나타났으나 표면행동은 유의하게 나타나지 않아 감정표현규칙 몰입의 조절효과가 일부만 확인되었다. 이러한 연구결과를 토대로 이론적 및 실무적 시사점과 향후과제를 제시하였다.
        5,800원
        112.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to identify differences in the Systemic reaction, Vertical jump and Side step of Judo, Taekwondo, Kendo elite athletes The Total Health Promotion Plan was used to measure systemic reactions, vertical jump and side steps. In the results of the study, systemic reaction was significantly different between Judo player and Taekwondo player (p<0.05). Vertical jump did not differ between groups. Side step was significantly different between Kendo player, Judo player, Judo player and Taekwondo player, Taekwondo player and Kendo player (p<0.05). This study suggests that systemic reaction, vertical jump and side step are different for each sport.
        4,000원
        113.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to examine the changes in reaction velocity and visual perception between genders participating in driving simulator training. Driving simulator training was performed on 46 adults (male: 20, female: 26) twice a week, 20 minutes per time, 8 times for a month. The results showed that after driving simulator training was significantly more effective for males than females (p<.01). Additionally, the difference in visual perception was also larger in males than in females and it was significantly more effective in males than females (p<.01). This study is expected to contribute to the understanding of differences in reaction velocity and visual perception between adults and handicapped persons of the same gender. The results of this study will also provide a guideline for driving rehabilitation education for handicapped persons in our society and, thereby, help implement driving rehabilitation training systematically.
        3,000원
        114.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is for the consideration of the existence tendency of Kudoa septempunctata in olive flounder. In general, muscle has shown a strong PCR positive reaction in spores containing tissues rather than non-containing tissues. However, blood PCR results showed opposed tendency. In various organs of the tested fish containing spores in muscle tissue, heart had shown positive reaction along with muscle at PCR analysis. Muscle fiber necrosis was observed at the histological observation, and this degeneration was common in both samples. The one sample was the PCR positive muscle containing spore and the other was the PCR positive muscle non-containing spore. Both of muscle tissues indicated a positive reaction at ISH (in-situ hybridization) against K. septempunctata.
        4,000원
        115.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        점토를 이용하여 세 종류의 새로운 형태의 변형된 유기물점토를 제조하였다. Cetylpyridinium chloride (CPC)를 점토에 층간 삽입시켜 OC-CPC를 합성하였고, Aluminium 축을 갖는 Al-PILC 만든 후, cetylpyridinium chloride를 Al-PILC에 삽입시켜 IOC-CPC 화합물을 합성하였다. IR과 TGA를 이용하여 이들 구조를 분석한 결과 층간 삽입반응이 성공적으로 이루어졌음을 확인할 수 있었다. X-ray 회절을 이용하여 층간 거리를 조사하였는데 OC-CPC가 제일 큰 값을 보여 주었다. 층간 구조를 갖는 화합물들은 삽입반응을 이용하여 구조를 변형시킬 수 있으며 이를 통해 층간거리, 표면적, 공간 크기, 화학적 친화성 같은 여러 물리적 성질들을 바꿀 수 있으므로, 본 논문에서는 자연점토를 이용하여 층간 반응을 통해 휘발성 유기화합물의 흡착에 쓰일 수 있는 유용한 유기점토 화합물을 합성하고 이들의 구조를 확인코자 하였다. 벤젠과 톨루엔의 흡착은 IOC-CPC나 Al-PILC에서 보다 OC-CPC에서 더 잘 이루어졌으며, 자연점토에서는 거의 흡착이 일어나지 않았다. OC-CPC 화합물에서는 친 소수성 성질이 크고 층간 거리도 증가했기 때문에 흡착이 잘 일어났다고 볼 수 있으며, 반면에 친수성이 큰 Al-PILC 에서는 벤젠과 톨루엔 같은 휘발성 유기물에 대한 흡착이 상대적으로 적게 일어났다.
        4,000원
        116.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Reaction-bonded silicon carbide (RBSC) is a SiC-based composite ceramic fabricated by the infiltration of molten silicon into a skeleton of SiC particles and carbon, in order to manufacture a ceramic body with full density. RBSC has been widely used and studied for many years in the SiC field, because of its relatively low processing temperature for fabrication, easy use in forming components with a near-net shape, and high density, compared with other sintering methods for SiC. A radiant tube is one of the most commonly employed ceramics components when using RBSC materials in industrial fields. In this study, the mechanical strengths of commercial RBSC tubes with different sizes are evaluated using 3-point flexural and C-ring tests. The size scaling law is applied to the obtained mechanical strength values for specimens with different sizes. The discrepancy between the flexural and C-ring strengths is also discussed.
        4,000원
        120.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted in an effort to investigate the effect of Maillard reaction products (MRPs) on enzymatic browning of burdock and their anti-oxidant activity. The MRPs were prepared by heating glucose and amino acids at 90°C, which served to produce a strong inhibitory effect on burdock polyphenol oxidase. As the reaction time of the solution containing glucose and amino acid increased at 90°C, the production of MRPs increased and intensity of the brown color deepened. When MRPs were prepared by heating at 90°C for five hours, the absorbance of MRPs from glucose and lysine was 6.44, while those of glucose and glycine was 1.95. The MRPs synthesized from the glucose and lysine also reduced the pH of MRPs from 5.60 to 4.51, but those from glucose and glycine decreased slightly from 5.57 to 5.33. The Michealis-Menten constant value (Km) of burdock PPO with pyrocatechol as a substrate was 16.0 mM, and MRPs were a non-competitive inhibitor against burdock PPO. The anti-oxidant activity of MRPs was measured by evaluating its radical scavenging activities of DPPH radicals, ABTS radicals and reducing power. The color intensity of MRPs produced by lysine and glucose were deeper than that produced by glucose and glycine. It was also found that MRPs produced from glucose and lysine exhibited stronger anti-oxidant properties than those produced by glucose and glycine.
        4,000원