검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 1,256

        484.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Bi0.5Na0.5TiO3 (BNT) based ceramics are considered potential lead-free alternatives for Pb(Zr,Ti)O3(PZT) based ceramics in various applications such as sensors, actuators and transducers. However, BNT-based ceramics have lower electromechanical performance as compared with PZT based ceramics. Therefore, in this work, lead-free bulk 0.99[(Bi0.5Na0.5)0.935Ba0.065](1-x)LaxTiO3-0.01SrZO3 (BNBTLax-SZ, with x = 0, 0.01, 0.02) ceramics were synthesized by a conventional solid state reaction The crystal structure, dielectric response, degree of diffuseness and electric-field-induced strain properties were investigated as a function of different La concentrations. All samples were crystallized into a single phase perovskite structure. The temperature dependent dielectric response of La-modified BNBT-SZ ceramics showed lower dielectric response and improved field-induced strain response. The field induced strain increased from 0.17% for pure BNBT-SZ to 0.38 % for 1 mol.% La-modified BNBT-SZ ceramics at an applied electric field of 6 kV/mm. These results show that Lamodified BNBT-SZ ceramic system is expected to be a new candidate material for lead-free electronic devices.
        4,000원
        485.
        2015.10 구독 인증기관·개인회원 무료
        The longevity and fecundity of Naranga aenescens adult were investigated at temperatures of 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, and 32.5°C. Adult longevity was influenced by temperature but there was no temperature effect of fecundity. Longevity decreased with increasing temperature: it was highest at 15°C (22.2 ± 3.51 days) and lowest at 32.5°C (6.2 ± 0.32 days). Total fecundity was highest at 25°C (1693 eggs) and lowest at 15.0°C (1115 eggs). The oviposition period was longest at 20°C (8.8 ± 0.57 days) and shortest at 32.5°C (4.1 ± 0.21 days). The oviposition model presented in this study consisted of two reproductive components (total fecundity and age-specific oviposition rate) and a survival component (age-specific survival rate). The relationship between adult developmental rate and temperature was described by the Logan 6 model (r2=0.98, p<0.0001).The age-specific survival rate was explained by a exponential function (r2=0.98, p<0.00001). The age-specific cumulative oviposition rate was described by the two-parameter Weibull function (r2=0.95, p<0.00001). Temperature-dependent fecundity was estimated using the Briere-2 model (r2=0.91, p<0.0125). Daily egg production of N. aenescens in relation to adult age and temperature was estimated.
        486.
        2015.10 구독 인증기관·개인회원 무료
        The Citrus Leafminer (CLM) larvae creates shallow tunnels in leaves of citrus (orange, mandarins, lemons, grapefruit, etc) and commonly attacks citrus young leaves. They spread almost worldwide (North America, Asia, Australia, etc) and difficult to control by chemicals due to their small size and their behavior of leaf rolling. Due to difficult of managing, our interest is preparing pheromone to control; Z7Z11-16;Al is known as the sex pheromone of this species in Japan. While blending Z7Z11-16;Al and Z7Z11E13-16;Al (3:1 ratio) is known as the pheromone of this insect in North America. Even though commercialized and mass produced already in overseas, there had been almost no report in Korea about synthetic studies and field screening results. The control of the regio-isomers is very important in this kind of pheromone synthesis. Our strategy is the regio-selective Wittig olefination reaction between E-pent-2-enyl(triphenylphsphonium)bromide (phosphonium salt) and the counterpart aldehyde using sodium hexamethyldisilazide (NaHMDS) as a base. All the spectroscopic data (1H, 13C, GC-Mass, etc) are nicely matched with the previously reported values. The field screening in the Jeju island is currently ongoing and will be reported.
        487.
        2015.10 구독 인증기관·개인회원 무료
        Due to its rapid development of resistance to nearly all arrays of acaricide, Tetranychus urticae is extremely hard to control using conventional acaricides. As an alternative control measure of acaricide-resistant mites, RNA interference (RNAi)-based methods have recently been suggested. A double-stranded RNA (dsRNA) delivery method using multi-unit chambers was established and employed to screen the RNAi toxicity of 42 T. urticae genes. Among them, the dsRNA treatment of coatomer I (COPI) genes, such as coatomer subunit epsilon (COPE) and beta 2 (COPB2), resulted in high mortality [median lethal time (LT50) = 89.7 and 120.3h, respectively]. The transcript level of the COPE gene was significantly (F3,9 = 16.2, P =0.001) reduced by up to 24% following dsRNA treatment, suggesting that the toxicity was likely mediated by the RNAi of the target gene. As a toxicity enhancement strategy, the recombinant dsRNA was generated by reciprocally recombining half-divided fragments of COPE and COPB2. The two recombinant dsRNAs exhibited higher toxicity than the respective single dsRNA treatments as determined using LT50 values (79.2 and 81.5h, respectively). This finding indicates that the recombination of different genes can enhance RNAi toxicity and be utilized to generate synthetic dsRNA with improved RNAi efficacy.
        488.
        2015.10 구독 인증기관·개인회원 무료
        The pheromone biosynthesis in Plutella xylostella is stimulated a neuropeptide, pheromone biosynthesis activating neuropeptide which is produced in subesophageal ganglion. The pheromone production is more active in the scotophase than in the photophase, which suggests that there may be changes of gene expression in the pheromone glands. To analyze gene expression related to pheromone biosynthesis, we performed transcriptomes of pheromone glands which were isolated at every 4 h. Eleven pheromone biosynthesis-related genes, acetyl-CoA carboxylase, fatty acid synthase, acyl-CoA dehydrogenase, enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, Δ9 desaturase, Δ11 desaturase, fatty acid reductase, alcohol oxidase, aldehyde oxidase, and aldehyde reductase were identified. Among these genes, the expression of aldehyde reductase and aldehyde oxidase were relatively higher in the scotophase than in photophase, which may affect increase of pheromone production in the scotophase. Expression of signal genes involving in pheromone biosynthesis such as acyl-CoA desaturase, FAR, PBAN receptor, fatty acid transporter and acyl-CoA binding protein did not exhibited any significant difference.
        489.
        2015.10 구독 인증기관·개인회원 무료
        A rapid cold hardening (RCH) and supercooling capacity usually play crucial roles in survival during the overwintering period in the tobacco budworm, Helicoverpa assulta, a freeze-susceptible species. Cryoprotectants such as polyol or sugar affect RCH and maintain fluid status of hemolymph. This study is performed to identify cryoprotectants as a RCH factor in H. assulta. Pre-exposure of H. assulta larvae to 4℃ significantly increased survival at -10℃ in all developmental stages from egg to adult. RCH was dependent on the duration of the pre-exposure period. RCH also significantly enhanced the supercooling capacity. Analysis of cryoprotectants from the hemolymph revealed that the pre-exposure treatment allowed the larvae to accumulate glycerol and trehalose among polyols examined. In addition, unknown materials from 2 peaks were also increased. TIC analysis revealed 3 predicted formulas for unknown materials, C26H24O20S or C3H4N6OS and C22H20O21. Glycerol-3-phosphate dehydrogenase (GPDH) and glycerol 3-phosphatase (G3P) that involving in glycerol biosynthesis were identified from the transcriptome of H. assulta 4th instar larvae. Based on the expression level of transcripts, the expressions of GPDH and G3P were relatively increased when compared to that of the control, suggesting that these genes contribute to overwintering and biosynthesis of glycerol.
        490.
        2015.10 구독 인증기관·개인회원 무료
        To clarify the geographical distribution of scrub typhus vectors in Korea, the first survey of chigger mites was conducted from 2005 to 2007 by collecting wild small mammals twice a year (spring and autumn) at 24 sites nationwide. The two predominant mite species were Leptotrombidium pallidum (52.6%) and L. scutellare (27.1%). However, the proportions of L. scutellare in southern areas, including endemic provinces such as Chungcheongnam-Do, Jeollabuk-Do, Jeollanam-Do, and Gyeongsangnam-Do, were relatively higher than in central Korean regions where L. pallidum was predominant. In autumn, the ratio of L. scutellare increased to 42% while the ratio of L. pallidum decreased. The geographical distribution map of the L. scutellare chigger index was identical to the incidence pattern of scrub typhus, whereas those of overall mites and L. pallidum showed no relationship with case incidence patterns. Distribution mapping analysis shows an identical geographical distribution of L. scutellare and epidemic incidence of scrub typhus in South Korea. The second periodical survey was performed from 2011 to 2013. The result suggests that the distribution of L. scutellare has not been changed remarkably in comparison to the first survey.
        491.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        미이라병은 Diaporthe/Phomopsis complex에 의해 유발되는병으로 콩 재배기간 중 따뜻하고 습한 환경에서 종자가 성숙되면 감염률이 높아지며 감염된 콩 종자는 외관상 품질뿐만아니라 종자 활력이 저하된다. 미이라병에 대한 연구를 수행하기 위하여 대만에 위치한 아시아채소개발연구센터(AVRDC)의 콩 시험포장에서 미이라병 병징을 보이는 콩 줄기를 채집하고 이로부터 3개의 곰팡이 균주(isolate)를 분리하였다. 배지위에서의 곰팡이 균사의 생육특성, 현미경하에서 관찰된 알파,베타 분생자(conidia)의 모양 그리고 PCR-RFLP 분석으로, 3개의 균주는 Diaporthe phaseolorum var. sojae 으로 확인되었다. 한편, 미이라병 저항성 육종을 위해서는 유전자원과 계통의 검정이 선행되어야 하는데, 인공접종을 위해서 분생자의최적 배양조건을 탐색하였다. 그 결과 배지는 PDA, 온도는24oC에서 잘 배양되었으며, 일장은 암조건에서는 균사체만 유도되고 분생자는 유도되지 않았으며, 24시간과 15시간의 일장에서는 균사체 유도 및 분생자의 유도 정도에 차이가 없었다.또한 잎-줄기와 꼬투리, 두 개의 접종 부위에 따른 미이라병감염률을 조사하였는데, 두 접종 부위에 따른 미이라병 감염정도는 통계적인 유의차는 나타나지 않았으나 잎-줄기에 접종한 개체 보다 꼬투리에 접종한 개체의 종자 감염률이 높은 경향을 보였다.
        4,000원
        492.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An experiment was conducted to study the potential of thermal treated oak sawdust(steaming and steam explosion) as horticultural medium component in plug seedlings production of Chinese cabbage(Brassica campestris L.). This study involves the chemical, physical characterization and growth test of thermal treated oak sawdust(steaming and steam explosion) in order to evaluate their use as components of horticultural media. A commercial peat moss and oak sawdust were used as control. The total carbohydrate, C/N ratio, pH, phenolic compound, total porosity and water holding capacity were 45.1g/100g dry wt, 425.1, 4.4, 141.8mg/g wt, 82.5%, 47.1% in oak sawdust and 39.2g/100g dry wt, 300.3, 4.7, 131.7mg/g wt, 84.9% and 49.2% in steamed oak sawdust and 30.3g/100g dry wt, 247.8, 5.7, 40.8mg/g wt, 92.3% and 51.7% in steam exploded oak sawdust, respectively. The mixtures of the horticultural media were prepared using different substrate as peat moss, oak sawdust, steamed oak sawdust, steam exploded oak sawdust and perlite to grow Chinese cabbage in a greenhouse. The seed germination, stem height and leaf area were 68%, 2.2cm, 1.1cm2 in OSP(containing 90% oak sawdust and 10% perlite) and 69%, 2.5cm, 1.5cm2 in SMP(containing 90% steamed oak sawdust and 10% perlite) and 87%, 3.0cm, 2.2cm2 in SEP(containing 90% steam exploded oak sawdust and 10% perlite), respectively. The leaf area SEP(containing 90% steam exploded oak sawdust and 10% perlite) was higher than that of PP(containing 90% peat moss and 10% perlite). This research indicates that steam exploded oak sawdust may be utilized as a suitable replacement for peat moss in horticultural media component for Chinese cabbage.
        4,200원
        493.
        2015.06 구독 인증기관·개인회원 무료
        This study integrates the cognitive appraisal theory and script theory, highlighting the bridging role played by recollective memory. The relationships between visitors’ appraisals, emotions, recollection, storytelling and repurchase intention as they relate to the luxury cruise trip experience were assessed. We developed 14 theoretical hypotheses from a literature review. We then tested these hypotheses using data collected from 300 luxury cruise passengers. To the best of our knowledge this study is the first to incorporate the cognitive appraisal approach into script theory in a luxury tourism setting. Our work discloses that these two theories complement each other and recollection is the tie between them. This research reinforces the theoretical literature on cognitive appraisal and script theory. Moreover, the luxury cruise sector is under pressure due to fierce competition and as a result there is a need to acknowledge the crucial determinants of tourists’ emotional reactions. An understanding of tourists’ emotional experiences, and their antecedents and consequences will aid in the formulation of strategic marketing, segmentation, and communication efforts. The results of our study confirm that different emotional reactions can be elicited due to the power of four appraisal dimensions: appetitive goal congruence, certainty, novelty and agency. The findings not only enrich the cognitive appraisal framework and script theory literature but also provide guidance for managerial and marketing strategies of cruise industry practitioners.
        494.
        2015.06 구독 인증기관 무료, 개인회원 유료
        Mitral valvular prolapse (MVP) in dogs is characterized by myxomatous valvular degeneration, which is caused by abnormal valvular thickening and incomplete coaptation of the mitral valve leading to mitral regurgitation. Mitral regurgitation causes left atrial and left ventricular enlargement. Pathogenesis of the disease is unknown, although some studies have suggested the involvement of endothelin and systemic connective tissue diseases. Mitral valvular prolapse in dogs commonly occurs in aged small dog breeds, including Malteses and Shih Zhus. This case study investigated the clinical features of an affected Maltese family and performed pedigree analysis. To the best of the authors’ knowledge, this is the first report of putative familial mitral valve prolapse and regurgitation in Maltese dogs. All family members in this study showed degenerative valvular changes and echocardiographic features of mitral valvular prolapse. Although disease progression differed, all dogs progressed to advanced heart failure stage within 2-3 years after diagnosis. Therefore, this is the first study to identify putative familial mitral valve prolapse in Maltese dogs. This finding suggests strong genetic etiology involved in the development of degenerative mitral valve disease in Maltese dogs. Furthermore, this finding could be a valuable resource for the identification of gene mutations in dogs with familial mitral valvular prolapse.
        4,000원
        495.
        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
        497.
        2015.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: This study set out to investigate the current state of microsurfacing in Texas and compared the results with the current state of the practice nationwide. METHODS: For this study, case studies were extracted from the existing literature and compared with the data obtained both from site visits by the research team and data obtained from a survey by Texas Department of Transportation (TxDOT) personnel. The successes and failures of microsurfacing are detailed and explanations of different issues are outlined. Forensic studies from Texas are included in the descriptions of those microsurfacings that failed when configured as part of the cape seals. RESULTS : Microsurfacing has been shown to be an effective pavement preservation technique when applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues. The failures experienced in Texas can mostly be attributed to cape seals and an inability to recognize structurally faulty pavement. CONCLUSIONS : When applied to an appropriate road, at an appropriate timing, and as a remedy for certain issues, microsurfacing has been shown to perform well in numerous case studies. The majority of microsurfacing failures are the result of poor project selection, usually involving the treatment being applied to structurally unsound pavement.
        4,000원
        498.
        2015.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to verify a correlation between flexi-bar exercise and improvement of trunk strength and body composition in juvenile soccer players. The subjects were 11 teenager juvenile soccer players who conducted flexi-bar exercise half an hour daily three times a week for eight weeks. They were tested for trunk muscles strength, body composition and correlation. The result showed that trunk muscles strength improved significantly( p<.01) and weight, Rt. arm muscle mass, Rt. leg muscle mass, and Lt. leg muscle mass(p<.05), Lt. arm muscle mass, trunk muscle mass, and body muscle mass(p<.01) improved significantly as well while Lt. arm fat mass, Rt. leg fat mass, and Lt. leg fat mass decreased significantly(p<.05). In the correlation analysis, the more trunk muscle mass and trunk muscles strength increased, the more muscle mass of body regions increased, which was a positive correlation whereas fat mass of body regions decreased, which was a negative correlation. It was verified that there was a correlation between flexi-bar exercise and improvement of trunk muscles strength and body composition for juvenile soccer players.
        4,000원
        499.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phasianus colchicus is not only a beautiful bird but also a great value in science and under the threat of endanger. Hence, the aim of this study was to isolate the pheasant male germ cells (mGCs) and then induce them into elongated sperm-like cells in vitro. The mGCs were purified and enriched by a two-step plating method based on the different adherence velocities of mGCs and somatic cells. The percentage of the c-kit positive cells and c-kit negative cells examined by flow cytometry analysis (FCA) was 92.87% and 2.57%, respectively. Subsequently, the mGCs were induced for 48h in DMEM/F12 medium supplemented factors such as retinol acid, testosterone and bovine FSH, followed by 5 weeks in culture. We found that some elongated sperm-like cells appeared initially in vitro under inducement of stimulated factors. The elongated sperm-like cells showed in the expression of changed morphology and post-transcriptional marker such as spermatid associated (SPERT), spermatid perinuclear RNA binding protein (STRBP), round spermatid basic protein 1 (RSBN1) and SPER1L. Moreover, in DNA content identified assay, induced cells showed that the 1C DNA population markedly increased in differentiated group but it was not change in undifferentiated group. Successful in vitro differentiation of pheasant testicular germline cells into spermatids appears to offer extremely attractive potential for the conservation of endangered birds and treatment of male infertility.
        4,000원
        500.
        2014.12 구독 인증기관 무료, 개인회원 유료
        As basic research to develop HEV and EV agricultural field machinery, the present study analyzes the technical trend of electric agricultural field machinery through product analysis, paper analysis, and patent analysis concerning HEV and EV in the automobile, construction machinery, and agricultural machinery sectors. For product analysis, the homepages of companies in these sectors were consulted to analyze the number of products of each company. For paper analysis, key words related to HEV and EV were selected, a search formula was drawn up, and articles search sites were consulted. And for patent analysis too, key words were selected and then a search formula was drawn up to examine published patent applications or registered patent applications, and trends were analyzed by structure, country, and year. The number of HEV and EV products were 17 in the automobile area, 8 in construction machinery, and 4 in agricultural machinery. Notably, in the agricultural machinery area, all HEV and EV products were from advanced companies overseas. In terms of papers, papers published in the past 5 years were searched and 33,195 papers were from the automobile area, 3,806 were from construction machinery, and 2,687, the fewest papers, were from the agricultural machinery area. A search of patents in the electric drive technology area in Korea, USA, and Japan, and Europe showed 1,927 valid patents, with 1,120 in Japan, 497 in USA, 193 in Korea, and 117 in Europe. Analysis of the trend of research on electric agricultural field machinery by product, paper, and patent shows the development of HEV and EV technology in Korea is insufficient compared to USA, Japan, and Europe, which means rapid technological development is needed.
        4,000원