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        검색결과 176

        81.
        2016.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.
        4,300원
        82.
        2016.11 구독 인증기관·개인회원 무료
        Membrane based water and wastewater treatment becomes more and more popular; however, membrane fouling is still a critical obstacle for its extensive use. Most of the membranes being used are polymeric and have limitations in physical, chemical, and thermal stability, even though various novel materials were introduced. In this study, metal membranes were fabricated to solve those weak points of polymeric membranes. We evaluated the physical properties of a metal membrane, such as pore size distribution, surface morphology, and water flux, and finally used the membrane for electrochemical oxidation of municipal wastewater with simultaneous hydrogen fuel generation. The metal membrane removed 50-70% of the feed organic matter by electrochemical oxidation; 10-30 % removal by electrochemical oxidation plus 40% by membrane rejection.
        83.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이산화염소는 살충효과를 지니며, 이는 이 물질이 발생시키는 활성산소에 기인된다. 살충효과를 주는 주요 원인으로 이산화염소의 세포독 성에 주목하고 있다. 본 연구는 이산화염소가 유발하는 세포독성이 활성산소에 기인한 아폽토시스 유발로 가설을 세우고 이를 검증하였다. 화랑 곡나방(Plodia interpunctella) 유충에 이산화염소를 주입한 결과 전체혈구수의 뚜렷한 감소를 보였고, 이후 처리 유충은 사망하였다. 아폽토시스 세포치사과정을 규명하기 위해 TUNEL (terminal deoxynucleotidyl transferase nick end translation) 분석법을 적용하였다. 곤충 세포주의 하나인 Sf9 세포에 서로 다른 이산화염소를 처리하고 TUNEL 분석법으로 관찰한 결과 처리 농도에 비례하여 아폽토시스 비율이 증가하였다. 다 음으로 서로 다른 농도의 이산화염소를 화랑곡나방 유충에 주입하고 혈구 세포를 TUNEL 분석법으로 관찰한 결과 이산화염소는 처리 농도에 비례하여 아폽토시스 유발을 나타냈다. 그러나 항산화제인 비타민 E를 이산화염소와 함께 처리하면 비타민 E의 농도에 비례하여 이산화염소의 아폽토시스 유발을 억제하고 이에 따라 살충률도 감소하였다. 이러한 결과는 이산화염소에 기인한 세포독성은 활성산소에 기인한 아폽토시스 유 발로 이뤄졌다는 것을 제시하고 있다.
        4,000원
        84.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the current study, oxidative decomposition of a volatile organic compound was investigated at room temperature and pressure. The experiment was carried out in lower ethylene concentration and with various higher gas flow rates. The reactor has 7 different compartments in which the reaction takes place independently. Plasma was generated inside each compartment by the application of alternating current (AC) voltage. 5 wt% manganese loaded and 5 wt% silver loaded 13X zeolite were used as catalysts. Bare zeolite showed higher ethylene decomposition efficiency than Ag loaded and Mn loaded zeolite. Ozone concentration was increased slightly while increasing the SIE, reached a maximum and started decreasing. Ag loaded zeolite also showed similar decomposition efficiency, but the concentration of ozone was greatly lowered.
        4,000원
        85.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Stockbridge damper was adopted to reduce the reponses of structures under earthquakes. A finite element analysis software, SAP2000, was used to simulate the structural response and the control device under dynamic loads. A 3 story frame model and the proposed control device, Stockbridge damper, were designed under laboratory conditions. In this research, a pendulum type tuned mass damper (PTMD) was also adopted in order to compare with the Stockbridge damper. Harmonic loads were applied to verity the control performance of both control devices in each mode. In results, it has been found that the Stockbirdge damper decreases significantly the responses of the structure more than the PTMD under the harmonic loadings. The El Centro and Northridge earthquakes were also applied in order to investigate the performance by both control devices. The responses of the building demonstrate that the Stockbridge damper reduces the response of the building structure during earthquakes more effectively than the PTMD.
        4,000원
        86.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Plant-parasitic nematodes are the most devastating group of plant pathogens worldwide and are extremely challenging to control. In the present study, we have performed a genome wide analysis to identify common genes among four nematode species consisting of root-knot nematodes (Meloidogyne incognita and Meloidogyne hapla), cyst nematode (Heterodera glycines), and free living nematode (Caenorhabditis elegans) respectively. Using their whole genome sequences, we predicted 15,274 genes from M. incognita, 38,149 genes from M. hapla, 8,061 genes from H. glycines and 23,894 genes from C. elegans, where, among the predicted genes, 1,358, 1,350, 1,401, 1,365 respectively from each nematode, code for common groups of proteins. Further, 2,067, 2,086, 1,566, 2,903 genes were recollected using Clusters of Orthologous Groups (COG) database. Under our search criteria, a total of 800 common genes were identified in all the four studied nematode genomes. The most annotated conserved genes were obtained from four different species using Basic Local Alignment Searching Tool (BLAST). Uni- Prot Taxon identifier database was used to elucidate their taxonomic classification such as 698 genes under kingdom Metazoa, 660 genes confined to Nematoda, 290 genes in Chordata and 660 genes falling under class Chromadorea. The biochemical characterization of proteins expressed by these genes was examined using Pedant-Pro sequence analysis. The protein length, molecular weight, isoelectric point (pI), and transmembrane domain of the coded proteins were at a range of 300 to 999 amino acids (40.9%), molecular weight of over 100 kDa (96%), pI from 4.5 to 5.5 (27.6%) and 0 (56.6%), respectively. To classify protein function, the obtained BLAST hits were assigned to Gene Ontology classification scheme. The fractions of protein function were distributed as cellular component, biological processes and molecular function of the cell (22.2%), multicellular organism process (15.8%) and binding (48.3%), respectively. The current study provides an excellent resource for nematode functional genomics studies, which can be utilized further for studies on role of genes involved in nematode biological processes.
        4,000원
        87.
        2016.06 구독 인증기관·개인회원 무료
        A permanent deformation model for asphalt concrete (AC) layers based on shear properties is developed and calibrated in this study. The indirect tensile (IDT) strength and uniaxial compressive strength (UCS) were used to determine the cohesion and friction angle of asphalt mixtures. Five types of asphalt mixtures with various air-void and binder contents are tested under different loadings and temperature conditions. Multiple regression analysis was conducted to develop permanent deformation model of asphalt mixtures which is a function of the air void, binder content, stress, and number of load cycles, temperature, and frequency. The regression model was verified by comparing the predicted and measured plastic strain. It was found out that the regression model has a correlation coefficient of 0.96 in determining plastic strain. Through the field WesTrack database, the permanent deformation model was calibrated to be applied to AC layers. After calibration, it is observed that the correlation coefficient is 0.86 for the measured and predicted rut depth. Finally, the model is validated using the field rutting performance obtained from Long Term Pavement Performance (LTPP) data sets. Based on the validation study, it can be concluded that the proposed model can successfully predict the permanent deformation of various asphalt mixtures in a wide range of loadings and temperature conditions in the field.
        88.
        2016.05 구독 인증기관·개인회원 무료
        High oxygen permeability and structural stability are required in the presence of high concentrations of CO2 for application of oxygen transport membrane in the oxy-fuel combustion process. MIEC membranes based on alkaline earth metal such as Ba0.5Sr0.5Co0.8Fe0.2O3-δ have low CO2 stability. Carbonates were formed over the surface of membranes including alkaline earth metal in the presence of CO2 and oxygen permeation fluxes are deteriorated. In this work, dense dual-phase hollow fiber membranes were prepared by a phase inversion spinning and sintering process. The oxygen permeation fluxes of dual-phase hollow fiber membrane were evaluated at various temperatures.
        90.
        2016.04 구독 인증기관·개인회원 무료
        로케트트랩의 유인물 조합에 따른 노린재류의 유인효과를 조사하였다. 로케트트랩에 의한 톱다리개미허리노린재의 유인수는 통발트랩보다 휴반에서 약 1.6∼2.3배, 팥포장에서 1.5∼2.0배 많았고, 매실원과 단감원에서 미국산트랩보다 각각 5.9∼9.9배 및 3.2∼5.2배 많았다. 팥포장에서 썩덩나무노린재는 로케트트랩에 잘 유인되었으나, 펀넬트랩과 통발트랩에는 유인되지 않았다. 또한 로케트트랩 내부에 solar fan을 장착하면 톱다리개미허리노린재의 유인수는 휴반에서 1.3배, 콩포장에 서 1.9배 증가하였고, 썩덩나무노린재는 콩포장에서 1.8배 증가하였다. 집합페로몬(AP)과 유인물 조합에 따른 노린재류의 유인은 톱다리개미허리노린재는 집합페로몬 단독대비 2가지 유인물 조합의 경우 톱다리개미허리노린재AP(톱다리AP)+콩 (1.9배)>톱다리AP+멸치(1.8배)>톱다리AP+썩덩나무노린재AP(1.5배)조합 순으로 많이 유인되었고, 3∼4가지 유인물 조합은 톱다리AP+썩덩나무노린재AP(썩덩나무AP)+콩+멸치(2.3배)>톱다리AP+썩덩나무AP+멸치(1.9배)>톱다리AP+썩덩나무AP+ 콩(1.5배)조합 순으로 많이 유인되었다. 한편, 썩덩나무노린재의 유인은 집합페로몬 단독대비 2가지 유인물 조합의 경우 썩덩나무AP+멸치(2.2배)>썩덩나무+콩(2.1배)>썩덩나무AP+톱다리AP(0.9배) 조합 순으로 많이 유인되었고, 3∼4가지 유인물 조합의 경우 썩덩나무노린재의 유인수는 썩덩나무AP+콩(2.6배)>썩덩나무AP+톱다리AP+콩+멸치(2.1배) 및 썩덩나무AP+톱 다리AP+멸치(2.1배)조합 순으로 많이 유인되었다.
        91.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Human tissue-type plasminogen activator (t-PA) is responsible for fibrin-specific plasminogen activation and plays a key role in fibrinolysis thereby aiding breakdown of blood clots in the vasculature. In the present study, in order to develop a system for production of recombinant st-PA and t- PAHis6 proteins in transgenic rice seeds, a DNA fragment encoding t-PA gene was selected and cloned to a plant binary vector (pMJ21) harboring a rice GluB1 promoter, an N-terminal signal peptide of the rice glutelin B1 protein and a Pin II terminator. The constructed plasmid was transformed into Agrobacterium tumefaciens LBA4404 (pSB1) to facilitate introduction into rice callus. The insertion of the st-PA and t-PAHis6 genes into the genome of transgenic rice seeds and their transcripts were confirmed using PCR, and Southern blot as well as RT-PCR, respectively. The highest level of recombinant st-PA expression as determined by enzyme-linked immunosorbent assay (ELISA) was found to be 2,916 ng/total soluble protein (mg) in transgenic rice seeds. The amount of recombinant proteins expressed in transgenic plants was estimated to range from 634 ~ 2,916 ng/TSP mg (st-PA) and 925 ~ 2,640 ng/TSP mg(t- PAHis6), respectively. Immuno-blot analysis of transgenic rice seeds revealed single bands of approximately 68-kDa representing recombinant st-PA and t-PAHis6 proteins. These results demonstrate the expression and in vivo activity of recombinant st-PA and t-PAHis6 in transgenic rice seeds. This study is a promising endeavor for production of recombinant pharmaceutical proteins using rice seed system.
        4,000원
        92.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On account of the increase in water demand and climate change, droughts are in great concern for water resources planning and management. In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using Weibull distribution model with 40-year records of annual minimum rainfall depth collected in major cities of Korea. As a result, the non-stationary minimum probable rainfall was expected to decrease, compared with the stationary probable rainfall. The reliability of ξ1, a variable reflecting the decrease of the minimum rainfall depth due to climate change, in Wonju, Daegu, and Busan was over 90%, indicating the probability that the minimal rainfall depths in those city decrease is high.
        4,000원
        93.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using generalized extreme value (GEV) distribution and Gumbel distribution models with rainfall data collected in major cities of Korea to reevaluate the return period of sewer flooding in those cities. As a result, the probable rainfall for GEV and Gumbel distribution in non-stationary state both increased with time(t), compared to the stationary probable rainfall. Considering the reliability of ξ1, a variable reflecting the increase of storm events due to climate change, the reliability of the rainfall duration for Seoul, Daegu, and Gwangju in the GEV distribution was over 90%, indicating that the probability of rainfall increase was high. As for the Gumbel distribution, Wonju, Daegu, and Gwangju showed the higher reliability while Daejeon showed the lower reliability than the other cities. In addition, application of the maximum annual rainfall change rate (ξ1·t) to the location parameter made possible the prediction of return period by time, therefore leading to the evaluation of design recurrence interval.
        4,000원
        94.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        곤충 생리현상의 가소성은 후생유전적 변화와 밀접하게 관련을 지을 수 있다. 이 가설을 증명하기 위해 광식성인 파밤나방(Spodoptera exigua)을 대상으로 상이한 먹이 조건에 따라 이 곤충의 발육과 DNA 메틸화에 영향을 주는 지 분석하였다. 동일한 코호트로 부터 얻은 갓 부화한 유충을 최종령에 이르기까지 세 가지 다른 먹이(대파, 배추, 인공사료)로 섭식 처리하였다. 이 결과 상이한 먹이 조건에 따라 유충발육속도, 용화 율 및 우화율에서 뚜렷한 차이를 보였다. 인공사료로 사육된 유충이 가장 빠른 유충발육속도와 높은 용화율 및 우화율을 나타냈다. 반면에 두 자 연 기주 가운데는 대파가 배추에 비해 파밤나방 발육에 양호하였다. 이러한 먹이에 따른 변이는 혈림프 단백질 및 혈당에서도 차이가 나타났다. 또한 발육과 연계되었을 것으로 추정되는 인슐린유사펩타이드(SeILP1) 유전자의 발현 정도도 먹이조건에 따라 상이했다. 단일항체를 이용하여 파밤나방 게놈 DNA의 시토신 메틸화를 분석한 결과 이 부위에 DNA 메틸화가 검출되었으며, 메틸화 정도는 먹이 조건에 따라 상이했다. 이 결 과들은 동일 집단의 파밤나방이 상이한 먹이 조건에 따라 발육차이를 나타내고 또한 시토신 메틸화에 변이를 보여 이 곤충의 생리적 가소성에 후 생유전적 인자가 작용하고 있는 것을 제시한다.
        4,000원
        97.
        2015.11 구독 인증기관·개인회원 무료
        본 연구에서는 평균입경 0.2, 0.5, 1,7㎛ 크기의 α-알루미나 분말을 이용하여 다공성 α-알루미나 지지체의 기공구조를 조절하고자 하였다. 다공성 α-알루미나 지지체는 슬립캐스팅공법을 이용하여 제조한 후 소결하였으며, 이 때 소결 온도가 지지체의 기공특성에 미치는 영향에 대하여 고찰하였다. 제조된 다공성 α-알루미나 지지체는 수은기공분석기를 이용하여 기공크기 및 기공률 등을 분석하였으며, 단일기체투과장치를 이용하여 기체 투과도를 측정하였다. 그 결과 평균입경 0.2, 0.5, 1.7㎛ 크기의 α-알루미나 분말을 이용하여 제조된 지지체는 각각 80, 130, 200㎚의 기공경을 가졌으며, CO2 단일기체에 대해 각각 1300, 1700, 5000GPU를 나타냈다.
        98.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이산화염소(ClO2) 훈증제는 살충효과를 나타낸다. 그러나 일부 곤충은 이산화염소에 대해 회피행동을 보여, 이 훈증제에 대한 방제효율을 크게 떨어뜨리고 있다. 본 연구는 이를 해결하기 위해 이산화염소 처리에 열처리를 추가하여 곤충의 이산화염소에 대한 회피행동을 줄여 살충효과를 극대화하는 전략을 세웠다. 이산화염소 훈증 처리는 거짓쌀도둑거저리(Tribolium castaneum)에 대해 살충효과를 주었으며, 시험 곤충이 노출된 조건에서 12 시간 처리할 때 유충에 대해서 383.67 ppm (153.63 - 955.78 ppm: 95% 신뢰구간), 성충에 대해서 397.75 ppm (354.46 - 446.13 ppm: 95% 신뢰구간)의 반수치사농도를 나타냈다. 그러나 먹이인 밀가루를 충분히 제공한 상태에서 이산화염소를 처리하면, 처리 약제에 반응하여 시험 곤충이 먹이 속으로 들어가는 회피행동을 보이면서 방제효과는 크게 낮아졌다. Y 튜브를 이용한 이 곤충의 먹이 선호성 행동을 분석한 결과 거짓쌀도둑거저리 성충은 이산화염소가 처리된 먹이를 회피하는 행동을 보였다. 그러나 촉각을 제거한 경우 이러한 회피행동은 둔화되었다. 거짓쌀도둑거저리에 6 시간 동안 46℃ 열처리를 하면 살충효과는 10% 이하로 낮지만, 처리된 성충들이 먹이 밖으로 나와 있는 것을 관찰하였다. 반면 400 ppm의 이산화염소를 단독으로 6 시간 처리한 결과 회피행동에 따라 전혀 살충효과를 보이지 않았다. 그러나 46℃ 열처리와 400 ppm의 이산화염소를 병행하여 6 시간 처리한 결과 살충효과는 95%로 크게 증가하였다. 따라서 열처리는 거짓쌀도둑거저리의 이산화염소에 대한 회피행동을 억제하여 살충효과를 증가시켰다.
        4,000원
        99.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study intended to investigate exploratorily the precedent factors affecting two types of perceived balances between work and life(family/leisure) and the antecedent ones affected by them, focusing on the metro train drivers. To attain this purpose, literature survey on the precedent factors, work-life balance, and antecedent factors was performed, and the study model was designed based on this survey, and then this model was analyzed empirically using Multiple-Regression. The results on the precedent factors showed that Job Demand, Self-Efficacy, and Age have significant effects on the negative transfer of work. On the other hand, it was shown that Affiliative Culture, Self-Efficacy, and Internal Locus of Control have significant effects on the family centered balance. And the results on the antecedent factors showed that family centered balance has significant effects on Job Satisfaction, Psychological Depression and Fatigue, Safety Behavior, and accident, and the negative transfer of work has significant effects on Physical and Psychological Depression and Fatigue, Emergency Stress, and Safety Behavior.
        4,800원
        100.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The 1/5 scale–down model of the Bycatch Reduction Device (BRD) from an Argentinean demersal trawl was tested in a circulating water channel. The BRD is designed to help small Hake (merluza, merluccius hubbsi) to escape from a trawl. It is settled in front of a trawl codend, and is equipped with selection grids that help small fish to escape from the gear and guiding panels that help fish to meet with the grids. Bars of the grids are wires covered by the PVC and other parts of the BRD are made of net. When the velocity was less than 0.65 m/sec (2.81 Kont when translated to real towing speed) which is slow speed compared with real towing speed, position between an upper guiding panel and an upper selection grid were good to help small fish to escape. When the velocity was more than 0.8 m/sec (3.41 Knot when translated to real towing speed) which is similar to and faster than real towing speed, it was considered that small fish may have difficulties in escaping because the gap was not enough between an upper guiding panel and an upper selection grid. The lower selection grid was sat on the bottom of the tank without an angle due to the weight that it carries. Improvements were proposed to position the panels and the grids better.
        4,000원
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