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        검색결과 181

        42.
        2017.11 구독 인증기관·개인회원 무료
        As ZIF materials have their unique properties such as high surface area, tunable pore structure, thermal and chemical stability, they can be used in various applications including gas separation and catalysis. For synthesis of ZIF membranes, fixing sub-micron ZIF seed particles on the support is challenging and important. In this work, ZIF-8 seed layer was synthesized by conversion synthesis of ZnO layer on support in H-mIm solution, followed by the secondary growth synthesis of ZIF-8 membranes. The parameters of conversion seeding had been investigated to control the reaction rate combining the dissolution rate of ZnO and the crystallization rate of ZIF-8. This ZIF-8 membranes showed the better coverage of seeding layer and improved gas separation properties compared with the membranes prepared by traditional dip-coating seeding method.
        44.
        2017.05 구독 인증기관·개인회원 무료
        As ZIF materials have their unique properties such as high surface area, tunable pore structure, thermal and chemical stability, they can be used in various applications including gas separation and catalysis. For synthesis of ZIF membranes, fixing sub-micron ZIF seed particles on the support is challenging and important. In this work, ZIF-8 seed layer was synthesized by conversion synthesis of ZnO layer on support in H-mIm solution, followed by the secondary growth synthesis of ZIF-8 membranes. The parameters of conversion seeding had been investigated to control the reaction rate combining the dissolution rate of ZnO and the crystallization rate of ZIF-8. This ZIF-8 membranes showed the better coverage of seeding layer and gas separation properties compared with the membranes prepared by traditional dip-coating seeding.
        45.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study concerned the analysis on the efficiency of the conversion of water tank type supply system to direct water supply system to examine the feasibility of the conversion, as well as the calculation of optimal conversion range that enables the supply of safe, high-quality water at stable pressure in accordance with the standards of water supply facility. The results of this research showed that when converting water supply system from water tank type supply system to direct water supply system, more nodal points could be properly converted and more reduction of electricity usage was expected in case water pressure rather than residence time was fixed. This means that higher efficacy can be obtained by fixing water pressure when converting water supply system. However, since the number of the locations that received on-spot inspection was small and the electricity usage measured was not exclusively by water supply facility, it is difficult to judge that such reduction of electricity usage accurately represents reduced electricity usage by water supply facility alone. therefore, after having secured on-spot information about a larger number of locations in apartment complexes that have converted water supply system, and utilizing information about electricity usage exclusively by water supply facility, the proposed method of this research could be applied to accurately deducing expected reduction of electricity usage by water supply facilities of various other apartment complexes. It is also considered possible to deduce an effective operation method of water supply system by finding out an area that shows low pressure or low residual chlorine concentration in the optimal conversion range of water supply, followed by estimating the proper location of pumping station or the proper chlorine dosage at the power purification plant that supply water to the target area.
        4,000원
        46.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ginger was steamed at 121 o C and 1.5 lb/in 2 for 30 min, dried at 60 o C for 12 h, and each step was repeated nine times. During processing, the lightness (L* value) and yellowness (b* value) decreased from 85.65±0.33 and 26.99±0.20 in the non-treated ginger to 56.91±0.25 and 16.69±0.06 in ginger treated for the ninth treatment. On the other hand, redness (a* value) increased from -1.51±0.03 to 7.34±0.08 on the eight treatment and then decreased to 7.21±0.04 on the ninth theatment. The contents of 6-gingerol decreased from 3.257±0.067 mg/g in the non-treated ginger to 0.567±0.036 mg/g on the theatment, whereas the contents of 6-shogaol increased from 1.299±0.050 mg/g to 2.999±0.089 mg/g on the sixth treatment and decreased to 2.099±0.039 on the ninth treatment. The contents of 10-gingerol decreased slightly from 1.106±0.125 mg/g to 0.806±0.026 mg/g. Unlike the 6- and 10-gingerol, the contents of 8-gingerol did not change greatly, with values between 0.916±0.005 mg/g and 1.106±0.005 mg/g being observed during processing. The tyrosinase inhibitory activities were increased from 43.42±11.45% in the non-treated ginger to 100% on the sixth treatment and then decreased to 51.98±7.36% on the theatment. The antioxidative activity was retained during processing.
        4,000원
        47.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The ISO (International Organization for Standardization) 9000 QMS (Quality Management System) standards specify requirements that need to demonstrate an organization’s ability to consistently provide products or services. Korean companies have been implementing ISO 9000 QMS to compete in global markets. ISO 9000 QMS standards have been revised in 1994, 2000, 2008, and 2015 since the first release in 1987. The key change in ISO 9001:2015 is focused on risk-based thinking. It means that risk inherent within an organization is early identified and proactively controlled by use of all aspects of QMS rather than taking preventive actions. In this article we did literature review mainly on empirical study related to motivation and operation performance of ISO 9000 implementation. We present the necessity of changeover, features of new version, and comparison between new and old version. In order to see how well organizations can implement the new ISO 9001:2015 we focus on manufacturing companies that are going to convert to ISO 9001:2015 registration. We collect their key characteristics such as yearly sales, the number of MPI (Management Performance Indicators), the number of KPI (Key Performance Indicators), the number of quality control engineers, quality control engineer work experience, and the degree of adaptiveness between new ISO 9001:2015 QMS and QMS currently operating in manufacturing companies. Especially the degree of adaptiveness is analyzed by correlation analysis, regression analysis, ANOVA, and t-tests to discover the relationships among their characteristics. We found out that the degree of adaptiveness is linearly related to quality control engineer work experience and the number of MPI and KPI that is practically utilized in manufacturing companies. We summarize the implications discovered to help manufacturing industry convert to ISO 9001:2015 registration.
        4,300원
        48.
        2016.06 구독 인증기관·개인회원 무료
        Oyster mushroom is one of mushrooms that are cultivated and consumed a lot in Korea. P. ostreatus 'ASI 2504(Suhan)' is a preferable cultivar to mushroom farmers because it has a dark pileus and a thick stipe. But it is very sensitive to environmental conditions, so farmers demand an alternative cultivar of ‘Suhan’ continuously. To develop a new cultivar, parental strains ‘ASI 2504(Suhan)’ and ‘ASI 0665(Heuktari)’ were selected from P. ostreatus’s various collected strains according to morphological characteristics. P. ostreatus ‘Soltari’ was developed by the method of Di-Mono crossing between dikaryotic strain ‘Suhan’ and monokaryotic strain derived from ‘Heuktari’. Analysis of the mitochondrial genetic characteristics was performed for primary selection in 100 crossed strains. The mitochondrial DNA profile of ‘Soltari’ was same as that of ‘Heuktari’, when mitochondrial DNA primer MtPo1 was used. And a nuclear DNA profile of ‘Soltari’ was similar as those of the parental strains, ‘Suhan’ and ‘Heuktari’, when RAPD(Random Amplified Polymorphic DNA) primer URP 1, 3 were used. The optimum temperature for mycelial growth was 30°C for ‘Soltari’. ‘Soltari’ was appropriate for middle high temperature to grow, especially 13~18°C. Fruiting body production per bottle (1,100mL) was about 158.6g. When compared to the control strain ‘Suhan’, the stipe’s length and thickness of ‘Soltari’ were similar to those of ’Suhan’. But the pileus diameter of ‘Soltari’ was a little shorter than that of ‘Suhan’, the former was 42.72mm, while the latter was 51.33mm. And the pileus thickness of ‘Soltari’ and ‘Suhan’ were 18.18mm and 25.46mm, respectively. ‘Soltari’ was more resistant at high CO2 concentration than ‘Suhan’ and the color of pileus of ‘Soltari’ was kept dark gray at high temperature. Therefore, it is suggested that this new cultivar ‘Soltari’ be an alternative of ‘Suhan’ and contribute to energy saving effect in oyster mushroom farms.
        49.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 광전환재의 사이즈가 다른 광전환 필름을 피복한 온실에서, 실내 생육 환경, 토마토 및 상추의 생육과 품질을 분석하는 것이다. 10μm 이상의 광 전환재를 이용한 광전환 필름(Micro 필름), 500nm 이하의 광전환재를 이용한 광전환 필름(Nano 필름)과 폴리에틸렌(PE) 필름을 2중 온실의 외피복재로 피복하였다. 내피복재는 0.06mm PE 필름을 사용하였고, 내피복 재 및 외피복재의 두께는 모두 0.06mm로 동일하였다. 광전환 필름의 인장강도, 인열강도, 신장율은 PE 필름과 유사하였다. 투광률은 Nano 필름이 600-750nm 및 전체 투광률에서 PE 필름보다 높았으며, Micro 필름은 PE 필름보다 전체 투광률이 낮았다. 온실 내 기온은 Micro 및 Nano 필름 온실이 PE 필름 온실에 비하여 약 2oC정도 높았고, 광전환 필름 온실 간의 유의적인 차이는 없었다. 지온은 Nano 필름 온실이 Micro 필름과 PE 온실에 비하여 각각 1.5, 3 정도 높았다. 토마토의 수량은 PE 필름 온실에 비해 Micro 및 Nano 필름 온실에서 각각 12%, 14% 정도 유의적으로 증가하였고, 당도 차이는 없었다. 그리고 광전환 필름 간의 유의적인 차이는 없었다. 상추의 수량은 Micro 필름 온실이 Nano 필름 및 PE 필름 온실에 비하여 각각 27%, 59% 높았다. Hunter의 적색 값a는 Nano 필름 온실에서 가장 높았다. 토마토와 같이 높은 광을 요구하는 작물은 투광률이 좋은 Nano 필름이 적합하였고, 상추와 같이 낮은 광을 요구하는 작물은 상추는 Micro 필름이 적합하다고 판단되었다.
        4,000원
        50.
        2016.05 구독 인증기관·개인회원 무료
        MOF(Metal-organic frameworks)의 일종인 ZIF-8은 큰비표면적과 높은 열적⋅ 화학적 안정성을 가지고 있어 분리막 재료로 많은 연구가 진행되고 있다. 특히, 3.4Å 크기의 기공입구와 11.6 Å 크기의 기공 크기를 가지고 있는 ZIF-8을 분리 막으로 합성시 프로필렌/프로판을 분자체 효과를 통해 분리해 낼 수 있다. 본 연구에서는 ZnO 층을 형성하고 이를 전환시켜 결함 없는 ZIF-8 막을 합성하고 이를 통해 프로필렌/프로판을 분리하고자 했다. 우선, 매크로기공을 가진 디스크 모양의 α-알루미나 지지체 위에 ZnO 층을 형성하고, 2-methylimidazole 용액에서 용매열 합성하여 ZnO를 ZIF-8 분리막으로 전환시켰다. 합성된 ZIF-8 분리막 은 XRD, SEM, 기체투과장치, GC 등을 이용하여 분석하였다.
        51.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lignocellulosic biomass conversion to biofuels such as ethanol and other value-added bio-products including activated carbons has attracted much attention. The development of an efficient, cost-effective, and eco-friendly pretreatment process is a major challenge in lignocellulosic biomass to biofuel conversion. Although several modern pretreatment technologies have been introduced, few promising technologies have been reported. Microwave irradiation or microwave-assisted methods (physical and chemical) for pretreatment (disintegration) of biomass have been gaining popularity over the last few years owing to their high heating efficiency, lower energy requirements, and easy operation. Acid and alkali pretreatments assisted by microwave heating meanwhile have been widely used for different types of lignocellulosic biomass conversion. Additional advantages of microwave-based pretreatments include faster treatment time, selective processing, instantaneous control, and acceleration of the reaction rate. The present review provides insights into the current research and advantages of using microwave-assisted pretreatment technologies for the conversion of lignocellulosic biomass to fermentable sugars in the process of cellulosic ethanol production.
        4,000원
        52.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 촉매 상 H2O2 전환에 의해 건식산화제가 생성되었으며, 이를 이용한 NO 산 화 공정에 대한 연구를 진행하였다. 건식산화제를 생성하기 위한 H2O2 촉매 전환에 관한 실험을 수행 한 결과, Mn계 촉매의 성능이 가장 우수하였으며, 이를 통해 생성된 건식산화제를 NO 산화공정에 주 입하여 다양한 운전조건에서 NO 산화특성을 조사하였다. 그 결과, H2O2 주입량, 산화반응온도, 그리고 공간속도가 NO 산화율에 크게 영향을 미치는 것을 확인하였다. 그리고, 산화반응온도와 H2O2 주입량 이 증가할수록 NO 산화효율이 증가하였으며, 공간속도가 증가할수록 NO 산화효율이 감소하였다.
        4,000원
        53.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 이산화탄소와 석탄을 사용하여 합성가스 CO를 생산하는 실험을 수행하였다. CO 합성특성은 KOH 촉매를 사용한 화학적 활성화 방법에 의해 조사되었으며, 제조공정은 CO2 전환 반응에서 석탄과 활성화 촉매 비율, 가스 유량과 반응온도 등과 같은 실험변수들을 분석함으로서 최적화 되었다. KOH 촉매를 사용하지 않은 경우, 반응온도 950℃와 CO2 유량 300 cc/min에서 65% CO2 전 환율을 얻었으며, 반면에 촉매를 사용한 경우 같은 반응조건에서 98.1%의 전환율을 얻었다. 석탄의 활 성화촉매 반응물의 비(석탄 : KOH = 4 : 1)가 다른 반응물 비에 대해 더 좋은 CO2 전환율과 CO 선 택도 보여줌을 알 수 있었다.
        4,000원
        54.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        팽이버섯 내에 존재하는 GAD 효소를 발효를 통해 활 성화 시켜 MSG를 GABA로의 전환율을 높이고자 하였다. 효과적인 고농도 GABA를 생산하기 위해 나노분말 팽이 버섯에다가 수경재배한 인삼을 첨가하여 야쿠르트발효기 에서 발효한 결과 GABA 전환율은 팽이나노인삼분말 발 효군(88%) > 팽이분말 발효군(52%) > 팽이나노분말 발 효군(44%) 순으로 나타났다. 이러한 결과는 MSG를 기질 로 첨가하는 식품에서 활용할 가치가 있으리라 사료된다.
        3,000원
        55.
        2015.11 구독 인증기관·개인회원 무료
        Perfluorinated sulfonic acid (PFSA)ionomersare representative proton-conductive polymer electrolyte materials with excellent chemical resistance. PFSA ionomers exhibitrelatively well-defined morphologies composed ofhydrophilic and hydrophobic moieties, which provide pathway and barrier for fast proton conduction and hydrogen permeation, respectively. A general way to change thedegree of hydrophilic-hydrophobic phase separation is thermal treatment at certain temperatures, particularly their glass transition temperatures. In this study, a simple way to transform their morphologies and to give improved proton conduction and reduced hydrogen permeationis suggested.
        58.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The metallicity distribution of globular clusters (GCs) provides a crucial clue for the star formation history of their host galaxy. With the assumption that GCs are generally old, GC colors have been used as a proxy for GC metallicities. Bimodal color distributions of GCs observed in most large galaxies have, for decades, been interpreted as bimodal metallicity distributions, indicating the presence of two populations within a galaxy. However, the conventional view has been challenged by a new theory that non-linear GC color-metallicity relations can cause a bimodal color distribution even from a single-peaked metallicity distribution. Using photometric and spectroscopic data of NGC 5128 GCs in combination with stellar population simulation models, we examine the effect of non-linearity in GC color-metallicity relations on transformation of the color distributions into the metallicity distributions. Although in some colors offsets are present between observations and models for the color-metallicity relations, their overall shape agrees well for various colors. After the offsets are corrected, the observed spectroscopic metallicity distribution is well reproduced via modeled color-metallicity relations from various color distributions having different morphologies. We discuss the implications of our results.
        3,000원
        59.
        2015.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        YNbO4:Yb3+/Er3+ is synthesized using a solid-state reaction process with a LiCl flux. The effects of the Er/(Yb+Er) ratios (REr) on the up-conversion (UC) and down-conversion (DC) spectra are investigated. The XRD data confirm that the Yb3+ and Er3+ ions are fully substituted for the Y3+ sites. The UC emission spectra activated by 980 nm consists of green and red emission bands, which originate from the Er3+ ions through an energy transfer (ET) process from Yb3+ to Er3+. The UC emission intensity depends on the REr value, and the findings demonstrate that REr ≤ 0.14 is suitable for an effective UC process. The DC emission spectra under 269 nm radiation of the synthesized powders exhibits not only a strong blue emission assigned to the [NbO4]3− niobates, but also green peaks that originate from the Er3+ ions through an ET process between [NbO4]3− and Er3+.
        4,000원
        60.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This paper presents a description of the current issues facing road managers regarding the surface-type conversion of lowvolume roads for cost savings. METHODS: The paper reviews previous works conducted toward this end, acknowledges gaps in the current research, and lays out what information is needed for further studies. RESULTS : If the cost to maintain an unsurfaced road is less than the cost of maintaining a surfaced road, then there is potential for cost savings for the management agency. However, the problem is bigger than simply maintaining the roads that already exist. If unsurfaced roads prove to be more economical than surfaced roads, then the cost to convert from a surfaced to an unsurfaced roadway, and vice versa, when necessary, must also be examined. CONCLUSIONS : No other studies have addressed the un-surfacing of a road for cost savings, and it is therefore unknown whether substantial savings can be realistically obtained by converting from a surfaced to an unsurfaced road. To determine whether a conversion policy would be a viable option, additional data and research are needed.
        4,300원
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