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        검색결과 28

        1.
        2023.07 구독 인증기관 무료, 개인회원 유료
        The body of knowledge from psychology has been useful to marketing for understanding consumer minds and behaviors (Jia et al., 2018). Daily activities, such as movie watching, grocery shopping, online shopping, drinking coffee (with friends or alone), and making an in-app purchases on social media, all involve consumption which is affected by the perceptions, attitudes, and behaviors of the decision maker (i.e., consumers). But when the ways in which we sense and interact with the world change, how does it shift our ways of communicating with each other and the processes of forming perceptions, attitudes, and behaviors?
        3,000원
        2.
        2018.12 구독 인증기관 무료, 개인회원 유료
        Exosomes are Nano-sized lipid vesicles secreted from mammalian cells containing diverse cellular materials such as proteins, lipids, and nucleotides. Multiple lines of evidence indicate that in saliva, exosomes and their contents such as microRNAs (miRNAs) mediate numerous cellular responses upon delivery to recipient cells. The objective of this study was to characterize the different expression profile of exosomal miRNAs in saliva samples, periodically isolated from a single periodontitis patient. Unstimulated saliva was collected from a single patient over time periods for managing periodontitis. MicroRNAs extracted from each phase were investigated for the expression of exosomal miRNAs. Salivary exosomal miRNAs were analyzed using Affymetrix miRNA arrays and prediction of target genes and pathways for its different expression performed using DIANA-mirPath, a web-based, computational tool. Following the delivery of miRNA mimics (hsa-miR-4487, -4532, and -7108-5p) into human gingival fibroblasts, the expression of pro-inflammatory cytokines and activation of the MAPK pathway were evaluated through RT-PCR and western blotting. In each phase, 13 and 43 miRNAs were found to be differently expressed (|FC| ≥ 2). Among these, hsa-miR-4487 (|FC|=9.292005) and hasmiR- 4532 (|FC|=18.322697) were highly up-regulated in the clinically severe phase, whereas hsa-miR-7108-5p (|FC|= 12.20601) was strongly up-regulated in the clinically mild phase. In addition, the overexpression of miRNA mimics in human gingival fibroblasts resulted in a significant induction of IL-6 mRNA expression and p38 phosphorylation. The findings of this study established alterations in salivary exosomal miRNAs which are dependent on the severity of periodontitis and may act as potential candidates for the treatment of oral inflammatory diseases.
        4,000원
        3.
        2018.10 구독 인증기관·개인회원 무료
        Bumblebee, Bombus ardens ardens (Apidae: Hymenopera), is an important resource for pollination that is most widely distributed in Korea. This study utilized microsatellite markers for investigation of genetic diversity and geographic relevance of the B. a. ardens populations in Korea. Through Next Generation Sequencing analysis, we identified 10 microsatellite markers and genotyped for 107 individuals of B. ardens collected from 10 populations. At each locus the number of alleles ranged from 10 to 23; the observed and expected heterozygosities ranged from 0.8909 to 1.0000 and 0.6641 to 0.8422, respectively; and inbreeding coefficient(FIS) ranged from –0.5053 to –0.0891. Significant deviation from the Hardy–Weinberg equilibrium was not observed at any locus. Population structure analysis indicated that there are three genetic groups in Korea with each Jeongseon and Ulleung-do composed of different gene pool from the remaining other populations. Similarly, Principal coordinates analysis also showed the same pattern. FST and RST analyses showed that each Jeongseon and Ulleung-do population had a significant genetic distance from other populations. Considering these results, genetic isolation of Ulleung-do may be explained by “Oceanic island” status and Jeongseon, which showed the positive FIS (0.069) and genetic isolation may be caused by its location on the east side of Baekdudaegan and by on-going inbreeding with a small population size.
        5.
        2017.04 구독 인증기관·개인회원 무료
        We collected four species of Osmia spp. consisting of O. cornifrons, O. pedicornis, O. taurus and O. satoi in Yeongwol, Bonghwa and Yechon locations. O. pedicornis was the dominant species, which accounts for 59.6% to 76.4% in the three locations. The sex ratio of Osmia spp. were from 1:1 to 1: 2.8 in O. cornifrons and from 1:2.8 to 1: 5.5 in O. pedicornis. The sex ratio of O. cornifrons and O. pedicornis was different in 3 locations. The female and male cocoons of O. cornifrons were the long elliptical-shaped and grey-brown color. The female and male cocoons of O. pedicornis were the long elliptical-shaped and polished dark-brown color. In both species of O. cornifrons and O. pedicornis, the cocoon size of the females was significantly larger than that of the male. Between those two species, the latter had a relatively bigger size than the former.
        6.
        2017.04 구독 인증기관·개인회원 무료
        In the age of sexual maturity of queen, mating occurred at 6.7% immediately after eclosion and it was the highest as 85.0% at 10 days after emergence. However, a remarkable decrease was occurred at 20 days after the emergence. With regard to oviposition rate, the highest rate was observed as 81.3-81.8% at 6 to 10 days of eclosion. The rate of colony foundation and progeny-queen production were the highest as 43.8% and 37.5%, respectively, at 8 days of eclosion. In the age of sexual maturity of male, mating rate was as high as 38.3% immediately after the eclosion, the highest as 80.0% at 25 days of eclosion, and 76.6% at 8 days of eclosion. The oviposition rate was the highest as 76.9% at 6 days of eclosion, and decreased to 75.0% at 8 days and 72.7% at 10 days of eclosion. Summarized, our results indicate that sexual maturity for mating of B. terrestris is most favorable 6-8 days after eclosion for queen and 6-10 days after for male.
        7.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, bulk nickel-carbon nanotube (CNT) nanocomposites are synthesized by a novel method which includes a combination of ultrasonication, electrical explosion of wire in liquid and spark plasma sintering. The mechanical characteristics of the bulk Ni-CNT composites synthesized with CNT contents of 0.7, 1, 3 and 5 wt.% are investigated. X-ray diffraction, optical microscopy and field emission scanning electron microscopy techniques are used to observe the different phases, morphologies and structures of the composite powders as well as the sintered samples. The obtained results reveal that the as-synthesized composite exhibits substantial enhancement in the microhardness and values more than 140 HV are observed. However an empirical reinforcement limit of 3 wt.% is determined for the CNT content, beyond which, there is no significant improvement in the mechanical properties.
        4,000원
        8.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Fe-Cu-Ni-Mo-C low alloy steel powder is consolidated by spark plasma sintering (SPS) process. The internal structure and the surface fracture behavior are studied using field-emission scanning electron microscopy and optical microscopy techniques. The bulk samples are polished and etched in order to observe the internal structure. The sample sintered at 900oC with holding time of 10 minutes achieves nearly full density of 98.9% while the density of the as-received conventionally sintered product is 90.3%. The fracture microstructures indicate that the sample prepared at 900oC by the SPS process is hard to break out because of the presence of both grain boundaries and internal particle fractures. Moreover, the lamellar pearlite structure is also observed in this sample. The samples sintered at 1000 and 1100oC exhibit a large number of tiny particles and pores due to the melting of Cu and aggregation of the alloy elements during the SPS process. The highest hardness value of 296.52 HV is observed for the sample sintered at 900oC with holding time of 10 minutes.
        4,000원
        11.
        2015.10 구독 인증기관·개인회원 무료
        The post-hibernated queens of Korean native bumblebee, Bombus hypocrita saporoensis were collected in Jeong-Sun, Korea to investigate their ecological characteristics and reared under the laboratory conditions; 27℃, 65% R.H. and darkness. The average weight of collected queens was 0.87±0.14g and 0.8g class was most abundant (34.7%) among eight weight classes. The rates of colony initiation, colony foundation and progeny-queen production were 76.3%, 60.0% and 42.5%, respectively. The durations up to colony initiation and colony foundation were 12.0±6.7 days and 49.3±2.4 days, respectively. The duration up to first worker, male and queen emergence were 22.2±3.0 days, 63.4±6.5 days and 63.5±8.7 days, respectively. The number of progenies was 108.5±26.0 workers, 186.7±70.7 males and 39.1±30.3 queens. The longevity of colony founded queen was 90.2±19.9 days whereas that of non-colonized queen was 35.9±30.3 days. Copulation time was 29.5±9.6 min. The number of eggs per egg cell laid new queen was 9.3±2.3 grains. An egg shaped as banana and it’s size was 1.12±0.10 mm in a width, 3.54± 0.16 mm in a length and 2.26±0.34 mg in a weight.
        12.
        2013.04 구독 인증기관·개인회원 무료
        To substitute for bluebottle fly, Chrysomyia megacephala which is being used for pollinator in mango fruit, and improve the pollinating effect of mango fruit which is also being increased as high value added crop recently in Jeju island of korea, 2 kinds of pollinator were used in analyzing and surveying of foraging activities on mango fruit in Seogwipo province. This study was conducted using 3 species of pollinator, Apis mellifera, Bombus terrestris and Chrysomyia megacephala with 3 treatment in vinyl-house condition respectively. Species of mango fruit, Irwin, was used in this experiment. A number of foraging activity of Apis mellifera and Bombus terrestris in hive showed highest 11 AM, and showed normal foraging activity in high temperature condition(28℃). Pollinating ratio of Bombus terrestris was shown 100% and over 95% in case of Apis mellifera. This ratio suggest that the 2 species of insects is effective as pollinator on mango fruit compared with bluebottle fly. Daily pollinating activity of Apis mellifera and Bombus terrestris was shown peak in 11 AM, but showed even activity from 9 AM to 3 PM in case of Chrysomyia megacephala. The pollinating characteristics of 3 species depends on illuminance but temperature, especially in case of Bombus terrestris was more affected by change of illuminance. Visiting time of Bombus terrestris and Apis mellifera on this flower was shown 2.8 and 3.4 seconds respectively. But Chrysomyia megacephala showed longer 10 times with 32.5 seconds than other insects. This results suppose that Chrysomyia megacephala showed as resting behavior for almost time on the flower not foraging activity to pollinate.
        13.
        2011.10 구독 인증기관·개인회원 무료
        To increase the fruit quality and productivity of the apricot, 2 species of insects, Apis mellifer, and Bombus terrestris were used for pollination in apricot field in Yeongcheon province. This study was conducted using 3 kinds of methods for pollination effect, natural condition, net-house treatment and control method. Also this experiment carried out in 2 places, vinyl-house and field condition. In case of field treatment of Apis mellifera, heating lamp experiment was added in net-house to find out the reason for harmful efficacy of low temperature early in the spring. Species of apricot, Mangum, was used in this experiment. A number of foraging activity of Apis mellifera and Bombus terrestris in vinyl-house showed higher than in field condition. But after stoping heating, showed low efficacy after showing peak in 1 PM. In field, Apis mellifera showed peak of foraging activity from 1 to 3PM, heating lamp experiment of field condition showed peak in 3 PM and then lowest tendency to evening suddenly. The fruit set rate of Apis mellifera and Bombus terrestris in vinyl-house showed higher with 92% and 89% respectively than control with 83%. In field, heating lamp treatment of Apis melliferawas was highest with 28% compared to Bombus terrestris with 25% and control with 15%. This results suppose that apricot in field was to be harmed by low temperature and frost in blooming time early in spring
        14.
        2011.09 구독 인증기관 무료, 개인회원 유료
        Historically the rise of contagious diseases and epidemics has been mainly caused by lack of food safety knowledge and negligence in personal hygiene. Food poisoning is an example that have been caused by lack of proper knowledge in food safety and personal hygiene. In order to prove this hypothesis, our team distributed a total of 225 survey sheets to middle school students. Survey questions mainly focused on the students' food safety knowledge, personal hygiene and regular dietary habits. We used 12 items to determine the stages of change in teenagers and divided into 3 stages of change: precontemplation stage (poor problem recognition), contemplation and preparation stage (some problem recognition), and action stage. Out of the 225 students surveyed, 105(47.1%) were male and 118 (52.9%) were female; 44.0% were in 7th grade, 33.0% in 8th grade, and 24.0% in 9th grade. In stages of change model, 3.8% were classified in pre-contemplation stage, 31.1% in preparation stage, and 65.1% in action stage. The awareness of the significance of food safety has a strong positive correlation with the stages of change food safety behavior (P<0.001), which suggesting our questionnaires regarding stages of change and food safety behavior were quite credential. Stages of change were also correlated with the consumption of unsanitary foods (P<0.01) and with the frequent hand washing (P<0.05). The stages of change showed a positive correlation with the food safety knowledge level (P<0.05). The four questions (out of 10) with the least percentage of correct answers were questions about the meaning of Norovirus (23.6%), the meaning of expiration date (43.6%), the meaning of food poisoning (36.4%), and proper food-handling (36.0%).
        4,600원
        16.
        2010.05 구독 인증기관·개인회원 무료
        The bumblebee, Bombus ignitus (Hymenoptera: Apidae), is a valuable natural resource that is one of the most notably utilized for greenhouse pollination in Korea. In order to understand the nature of genetic relationships, gene flow, and population structure of the species we sequenced a partial COI gene of mitochondrial DNA (mtDNA) corresponding to “animal barcode” region and the complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA (nrDNA) collected from Korean localities. Although the 658-bp long mtDNA sequence provided only six haplotypes with the maximum sequence divergence of 0.61% (4 bp), the ITS sequences provided 84 sequence types with the maximum sequence divergence of 1.02% (21 sites), confirming better applicability of the ITS sequences to the study of intraspecific variation. The complete ITS2 sequences of B. ignitus were shown to be longest among known insects, ranging in size from 2,034 bp ~ 2,052 bp, harboring two duplicated repeats. Overall, a very high per generation migration ratio, a very low level of genetic fixation, and no discernable hierarchical population/ population group were noted to exist among populations of B. ignitus on the basis of both molecules, thus suggesting that the B. ignitus populations on the Korean peninsula are panmictic, which is consistent with our understanding of the dispersal capability of the species
        17.
        2009.10 구독 인증기관·개인회원 무료
        The bumblebee, Bombus ignitus (Hymenoptera: Apidae), is a valuable natural resource that is one of the most notably utilized for greenhouse pollination in Korea. In order to understand the nature of genetic relationships, gene flow, and population structure of the species we sequenced a partial COI gene of mitochondrial DNA (mtDNA) corresponding to “animal barcode” region and the complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA (nrDNA) with the individuals collected from Korean localities. Although the 658-bp long mtDNA sequence provided only six haplotypes with the maximum sequence divergence of 0.456% (3 bp, from 91 individuals), but the ITS sequences provided 33 sequence types with the maximum sequence divergence of 0.78% (16 bp, from 35 individuals), confirming better applicability of the ITS sequences to the study of intraspecific variation. The ITS2 sequences of B. ignitus were shown to be the longest among known insects, ranging in size from 2,034 bp ~ 2,045 bp and harbored two duplicated repeats, indicating unusual structure of B. ignitus ITS2 sequences compared with other insect ITS sequences. Overall, a very high per generation migration ratio, a very low level of genetic fixation, and no discernable hierarchical population/population group were noted to exist among populations of B. ignitus on the basis of both molecules, thus suggesting that the B. ignitus populations on the Korean peninsula are panmictic, which is consistent with our understanding of the dispersal capability.
        18.
        2009.05 구독 인증기관·개인회원 무료
        The bumblebees, Bombus species are valuable natural resources being utilized for greenhouse pollination. Low level of genetic variation of Bombus species has been reported previously. In this study, we sequenced complete internal transcribed spacer 2 (ITS2) of the nuclear rDNA from 100 individuals of B. ardens collected from seven localities in Korean peninsula. The ITS2 sequence of B. ardens is longest, ranging in size from 1,940 bp-1,954 bp among known in insects, which ranges approximately from 241 bp-1,728 bp. The ITS2 sequences have ~51% of C+C content and contain each two 27 bp repeats, 20 bp repeats, 33 bp repeats, and 34 bp repeats at the beginning. Such repeats were not found in other insects. Uncorrected pairwise distance among 96 sequences that were obtained from 100 individuals revealed a maximum sequence divergence of 1.03%. Genetic diversity (π) of each population ranged from 0.007801 to 0.009627, and the lowest diversity was obtained from islet population of Ulleungdo, indicating possibly small, isolation of the population. Significant level of genetic distance was only found when Ulleungdo population was compared to two other mainland populations. Except for this, overall, a very high rate of per generation migration ratio (Nm=7.1-infinite) and a very low level of genetic fixation (FST=0-0.06546) were detected between pairs of localities. Analysis of hierarchical relationships among localities consistently revealed no statistically significant structure among populations. Taken these together, the B. ardens populations on the Korean peninsula are panmictic this is consistent with our understanding of the dispersal capability.
        19.
        2009.05 구독 인증기관·개인회원 무료
        The bumblebee, Bombus ardens, is a valuable natural resource, and is most notably utilized for greenhouse pollination. In order to gain a greater understanding of the population genetic structure and the genetic diversity of this species, we sequenced a portion of the mitochondrial COI gene corresponding to the “DNA Barcode” region (658 bp) from 160 individuals collected over 15 Korean localities. Uncorrected pairwise distances among the eight haplotypes suggested low intraspecific genetic diversity, with a maximum sequence divergence of 0.3%. Such a low level of intraspecific genetic diversity was further reflected in local populations, particularly to islet populations, such as those of Youngheungdo, Jakyakdo, and Ulleugdo, which had zero genetic diversity. Geographically, one haplotype (BARBA01) was widespread and dominant, with a frequency of 90.6% (145 among 160 individuals). Other haplotypes were restricted to one to three localities and had low frequency. Overall, a very high rate of per generation female migration ratio (Nm= 4.6 to infinite) and a very low level of genetic fixation (FST= 0 to 0.099) were detected between pairs of localities, suggesting that the B. ardens population sonthe Korean peninsula are panmictic, which is consistent with our understanding of their dispersal capability.
        20.
        2008.10 구독 인증기관·개인회원 무료
        To understand geographic genetic variation of the species and relationships among populations of the bumble bee, Bombus ardens, that is utilized as green house pollinator we expanded our investigation by sequencing somewhat longer mitochondrial DNA (mtDNA) fragment, covering some uninvestigated regions within the species distribution, and analyzing the sequence data in terms of population genetic structure. For the purpose of study, a portion of mitochondrial COI gene, corresponding to "DNA Barcode" region (658 bp) was sequenced from 160 individuals of B. ardens collected over 15 localities in Korea. The sequence data revealed overall relatively low genetic diversity within species, with a maximum sequence divergence of 0.3%. Geographically, one haplotype (BARBA01) was found in all localities surveyed, with the frequency of 91% (145 among 160 individuals), whereas other haplotypes were found in a locality mostly as a single individual, suggesting that haplotype distribution can be summarized as coexistence of widespread, one dominant haplotype and regionally restricted, other haplotypes. Overall, very high rate of per generation female migration (Nm = 4.6 ~ infinite) and very low level of geographic substitution (FST = 0 ~ 0.099) among localities were characteristic. Although some populations were genetically subdivided from the remaining localities in the hierarchical analysis, there was regional polarity on this subdivision. Taken together with gene flow estimates, the nature of genetic divergence of the bumble bee populations is characterized as one that possessing low genetic diversity, high gene flow, and wide spread of one dominant haplotype, consistent with the previous finding. To have further detailed information of this valuable genetic resource, further longer and variable molecular portion is under investigating.
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