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        검색결과 482

        102.
        2018.10 구독 인증기관·개인회원 무료
        4,4’-dichlorodiphenyltrichloroethane (DDT) has been re-recommended by the World Health Organization for malaria mosquito control in Africa. Previous DDT use has resulted in predisposition of resistance, and with continued use resistance will increase further in terms of level and extent. Drosophila melanogaster is a model dipteran that has many available genetic tools, has been widely used for elucidating insecticide resistance mechanisms, and is related to malaria mosquitoes allowing for extrapolation. The 91-R strain of D. melanogaster is highly resistant to DDT (>1500-fold); however, there is no mechanistic scheme that accounts for this level of resistance. Recently, reduced penetration, increased detoxification, and direct excretion have been identified as resistance mechanisms in the 91-R strain. Their interactions, however, remain unclear. Use of Gal4/UAS-RNAi transgenic lines of D. melanogaster allowed for the targeted knockdown of genes putatively involved in DDT resistance and has identified the role of several cuticular proteins (Cyp4g1 and Lcp1), cytochrome P450 monooxygenases (Cyp6g1 and Cyp12d1), and ATP binding cassette transporters (mdr50, mdr65, and mrp1) in increased sensitivity to DDT. These findings have been further validated in 91-R flies using a nanoparticle-enhanced RNAi strategy, directly implication these genes in DDT resistance in 91-R flies.
        103.
        2018.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 고지방·고콜레스테롤 식이 흰쥐에서 곰보배추 파우더가 간조직의 항산화 효소활성 및 산화적 손상에 미치는 영향을 관찰하였다. 실험군을 4군으로 나누어 정상 식이군, 고지방·고콜레스테롤 식이군, 고지방·고콜레스테롤 식이에 곰보배추 파우더를 5% 및 10% 첨가한 군으로 각각 나누었다. 간 조직 중의 항산화 효소계인 GSH-px, catalase 및 SOD 활성은 정상군에 비해 HF군에서는 감소되는 경향을 나타내었으나 HF군에 비해 곰보배추 파우더 공급군에서 유의적으로 증가되었다. Superoxide radical 함량을 mitochondria 및 microsome에서 측정한 결과 정상군에 비해 HF군에서 유의적인 증가를 나타내었으나 곰보배추 공급으로 유의하게 감소되었다. 특히 microsome에서는 군간의 유의한 차이도 나타내었다. 간조직의 cytosol 및 mitochondria에서 H2O2의 함량에서는 곰보배추 공급군 모두에서 유의적인 감소로 정상군 수준을 나타내었다. 혈청에서 간수치 GOT 및 GPT를 측정한 결과 10%의 곰보배추의 공급으로 HF군에 비해 유의적으로 감소되었다. 간조직의 microsome 및 mitochondria에서의 산화단백질 함량 또한 곰보배추 파우더의 공급으로 유의적으로 감소하였다. 과산화지질의 함량을 간조직에서 관찰 한 결과 고지방·고콜레스테롤 식이로 인해 증가된 과산화지질이 곰보배추 파우더를 공급한 군에서 유의한 감소를 나타내었다. 곰보배추의 공급으로 고지방·고콜레스테롤 식이로 손상된 간조직의 항산화계는 곰보배추 내 함유되어진 여러 생리활성 물질들이 항산화효소의 활성을 증가시켜 체내에서 생성된 free radical에 의한 산화를 억제시켰으리라 사료되어진다. 이로 미루어 곰보배추는 체내 조직의 산화를 억제하는 항산화작용에 효과적으로 기여함을 알 수 있었다.
        4,000원
        106.
        2018.05 구독 인증기관·개인회원 무료
        본 연구에서는 roll to roll (R2R) 설비를 이용해 폭 60 cm의 역전기투석용 양이온 및 음이온교환막을 제막했다. 양이온 및 음이온교환막의 전해질로 아크릴아마이드계 술폰산 및 암모늄염, 가교제로 다이아크릴아마이드를 사용했다. 또한, 지지체로 16 um 두께의 PE계 다공성 필름을 사용했다. R2R 설비로 제작된 양이온 및 음이온교환막은 swelling 후 18 um의 두께, 0.6 Ω⋅cm² 이하의 저항, 85% 이상의 permselectivity, 1.3 meq g-1 이상의 ion exchange capacity(IEC)를 지니고 있었다. 또한, 제조된 이온교환막의 전극 유효면적 5 × 5 cm의 역전기투석 셀 test 결과 2.5 W/m²의 전력밀도를 보였다.
        107.
        2018.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Epitaxial (1120) a-plane GaN films were grown on a (1102) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient H2/NH3 mixture gas at 1140℃ after carbonization by the pyrolysis in ambient H2 at 1100℃. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ω-2θ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After Ar+ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.
        4,000원
        108.
        2018.04 구독 인증기관·개인회원 무료
        충남 공주시 묵논에서 생육하고 있는 식물을 대상으로 식물의 기능적인 특징을 알아보기 위해 Grime의 CSR (Competitive, Stress tolerant, Ruderal) 전략 계획에 따라 분류 및 평가하였다. 식물의 생활사 유형을 분류하기 위해 각 분류군마다 성체 단계의 3개체를 선정하여 수관높이 (canopy height), 건물함량(dry matter content), 잎의 건물 량(leaf dry matter), 엽면적(specific leaf area), 개화기간 (flowering period), 개화시기(flowering start) 그리고 측아 확장(lateral spread)의 데이터에 관한 자료를 수집하였다. 그 결과, 멸종위기식물인 독미나리(Cicuta virosa)와 전주물꼬리풀(Dysophylla yatabeana)는 각각 CR, C/CR이었 고, 외래식물인 미국가막사리(Bidens frondosa)는 C/CR 이였다. 물달개비(Monochoria vaginalis), 벼(Oryza sativa) 그리고 피(Echinochloa utilis)는 각각 CR, C/CR 그리고 C/CR이었다. 묵논에서 생육하고 있는 6종의 식물들은 CR과 C/CR 두 가지의 유형이 나타나는 것으로 보아 모두 경쟁과 교란에 내성이 강한 식물임을 의미한다. 이러한 결과는 묵논에서 생육하고 있는 6종의 식물들은 모두 경쟁과 교란에 내성이 강한 경쟁자 식물(C/CR)과 경쟁형 마을식물(CR)로 묵논은 자원이 풍부하고, 교란이 심한 환경 특성을 갖는다는 것을 의미한다.
        109.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 강우 발생빈도의 불규칙한 변화로 홍수 및 가뭄 피해가 증가함에 따라 불규칙한 자연현상의 특 성을 예측하는 확률론적 방안들이 관심을 받고 있다. 본 연구에서는 자연계 현상을 확률론적으로 예측 하는 기법인 플랙탈이론의 허스트지수(Hurst exponent)를 이용한 자기유사성 평가를 전국 64개 기상관 측소의 월강수량 자료를 대상으로 실시하였다. 1986년부터 2015년까지 총 30년 동안의 월강수량을 평 가한 결과 허스트지수는 H=0.97~0.99의 범위로 나타났다. 이는 H>1/2의 양의 상관관계를 보이며, 자 기유사성을 가지는 것으로 평가될 수 있어 기존의 축척된 자료를 통해 향후의 이상강우에 대한 예측이 가능하다는 사실을 보여주는 것으로 나타났다.
        4,000원
        110.
        2017.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        H2O maser emission at 22 GHz in the circumstellar envelope is one of the good tracers of detailed physics and kinematics in the mass loss process of asymptotic giant branch stars. Long-term monitoring of an H2O maser spectrum with high time resolution enables us to clarify acceleration processes of the expanding shell in the stellar atmosphere. We monitored the H2O maser emission of the semi-regular variable R Crt with the Kagoshima 6-m telescope, and obtained a large data set of over 180 maser spectra over a period of 1.3 years with an observational span of a few days. Using an automatic peak detection method based on least-squares fitting, we exhaustively detected peaks as significant velocity components with the radial velocity on a 0.1 km s−1 scale. This analysis result shows that the radial velocity of redshifted and blue-shifted components exhibits a change between acceleration and deceleration on the time scale of a few hundred days. These velocity variations are likely to correlate with intensity variations, in particular during flaring state of H2O masers. It seems reasonable to consider that the velocity variation of the maser source is caused by shock propagation in the envelope due to stellar pulsation. However, it is difficult to explain the relationship between the velocity variation and the intensity variation only from shock propagation effects. We found that a time delay of the integrated maser intensity with respect to the optical light curve is about 150 days.
        4,000원
        111.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper aims at finding some lessons applicable to successful implementation of ‘The 3D Printing R/D Project’ through both examining the process of adopting overseas industrialized housing production technological knowhow by home builders during the 1970's~1980's period and thereafter until now the various efforts to adjust the technologies efficiently to the Korea‘s unique situation. Some meaningful lessons can be summarized as follows; Ⅰ) Deep understanding of 3DP technological know-why along with its inheritance, Ⅱ) Readjusting of R/D period and goals(cf. Global leader Winsun's 15 years experiment), Ⅲ) Restructuring for more collaborative R/D B&E system among participating researchers Ⅳ) Fostering 3DP expert-engineers and technicians from the early stage, Ⅴ) Clearing legal barriers in users' adopting 3DP methods necessary, Ⅵ) Development of appropriate building material besides concrete. Therefore, it is highly recommended that the above-mentioned 6 lessons positively accepted and applied to the Research Implementation Plan in due course, especially by KICT consortium and KAIA under the guidance of Ministry of Land, Infrastructure and Transport.
        4,000원
        113.
        2017.11 구독 인증기관·개인회원 무료
        An all-silica deca-dodecasil 3R (Si-DDR) zeolite with a pore size of 0.36*0.44 nm2 is highly desirable for membrane-based separation of CO2 from N2, which critical in the post-combustion carbon capture process, via molecular recognition of their slight size difference. For the first time, we acquired h0h-oriented, hydrophobic DDR zeolite films through epitaxial growth of a DDR seed layer with a structure directing agent of methyltropinium iodide. The degree of the out-of-plane orientation and inter-growth was increased with the secondary growth time, while reducing the defects that provide non-selective pathways. The resulting DDR membrane showed a CO2/N2 separation factor (SF) as high as 11.9 at 50°C under dry conditions. More desirably, it could achieve a much enhanced CO2/N2 SF of up to 15.9 at 50°C in the presence of H2O vapor.
        115.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Improvement of living and life style led to increased sales of frozen milk products, such as ice creams or ice bars. These frozen milk products are commonly stored in a small refrigeration stocker. R-502, which has long been used as the refrigerant of a stocker, is being replaced with R-404A due to the ozone layer depletion issue. In this study, thermal analysis was conducted for the stocker, and the results are compared with experimental data. For the compressor analysis, performance curves were used. Evaporator or condenser was discretized into small volumes, and energy balance was applied. Capillary tube was also discretized into small volumes, and energy and momentum balance were applied. Comparison with the test data of the stocker having 500 liter internal volume revealed that the condensation or evaporation temperature was predicted well except for the initial start-up period. Slightly lower prediction (maximum 4oC) was obtained for the stoker room temperature at the initial operation period. The effect of radiation heat transfer for prediction of the stocker room temperature was assessed.
        4,000원
        116.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we compared the efficiencies of national R&D investments between NT (Nanotechnology) areas in terms of papers, patents, and commercializations, and found ways to improve the efficiencies of national R&D investments for each NT area. This is in response to huge R&D investments government has made recently in NT areas.Here, we collected data on investments, papers, patents, and commercializations for the R&D projects in NT areas through National Science & Technology Information Service. Based on the data, we analyzed the investment and performances (papers, patents, and commercializations) for each NT area, calculated the efficiency for each NT area, and compared the efficiencies between NT areas. Next, using cluster analysis, we identified several NT areas with similar characteristics in terms of paper efficiency, patent efficiency and commercialization efficiency. Finally, we derived implications for the efficiency enhancement for each grouping.The cluster analysis showed that there could be two groups, one being low in terms of technological outcome (papers and patents) efficiencies and high in terms of commercialization efficiencies, while the other being high in terms of technological outcome (papers and patents) efficiencies and low in terms of commercialization efficiencies. Therefore, the strategy for one group calls for support for technology transfer or technology introduction from other R&D performers and grant of guidance for improving R&D performers’ commercialization ability to other R&D performers while the strategy for the other group calls for R&D support for transfer of technology to other R&D performers, activation of technology transfer and support for commercialization of R&D performers.
        4,000원
        118.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to distribute agricultural robots to the fields, based on the review of Japanese trends, three preliminary tasks and implications for the development of agricultural robots in Korea are derived as followings. The first result is that farmers are small-scale, agricultural robot is necessary to standardize through the public-private partnerships and reduce the supply price through the utilization of existing technologies and components. Secondly, the car-based robots are GPS-based system, and it is necessary to construct a nation-wide regional base stations that can trensmit the GPS correction signals free of charge in real time. Third, additional research is needed to cope with the unexpected situation in the fields, such as obstacle avoidance technology, robot safety evaluation technology, and safety standard development. In addition, although agricultural robots are being developed in Korea, a step-by-step approach is necessary for solving the above-mentioned pre-requisites for field distribution. In the first stage, it is necessary to supply an autonomous straight guidance system that assists the worker. The second stage is the spread of cooperation system between human and robot. The third stage is a complete robot system, in which the robot works on its own. Therefore, the supply of agricultural robots needs to be approached sequentially.
        4,000원
        119.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Stable Isotope Analysis (SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <50 μm), large sized POM (>50 μm), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.
        4,000원
        120.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The external R&D, which includes the adoption of the external technology and knowledge in addition to the internal R&D, is one of important factors for the innovation. Especially for small and medium-sized enterprises (SMEs), the external R&D has been considered as a key factor to carry out the innovation more efficiently due to the limitations of their resources and capacities. However, most of extant studies related to external R&D have focused on analyzing the influence of external R&D on innovation outputs or outcomes. Only a few studies have explored the impact of external R&D on the innovation efficiency. This study therefore investigates whether the external R&D effects the industry’s innovation efficiency and productivity. On this study, we used Korean manufacturing industry data of SMEs from 2012 to 2014 and employed a global Malmquist productivity analysis technique, which is based on the Data Envelopment Analysis (DEA), to assess the innovation efficiency and productivity. Innovation performances of external R&D group and internal R&D group are compared. Then, the sectoral patterns of both innovation efficiency and productivity are analyzed with respect to the technological intensity, which is introduced by OECD. The results show that the gap of innovation efficiency between external and internal R&D groups has gradually decreased because of the continuous improvement of the external R&D group’s performance, while the external R&D group lag behind the internal R&D group. In addition, patterns of the innovation efficiency and productivity change were different depending on the technological intensity, which means that the higher the technological intensity, the greater the effect of external R&D.
        4,300원