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        검색결과 24

        1.
        2023.07 구독 인증기관·개인회원 무료
        This study examined the combined effects of scarcity appeals and time remaining from the travel date on attitudes toward advertising and purchase intention. The results lead to a rationale for disparate advertising strategies of scarcity appeals considering the temporal distance of a consumer's hotel booking.
        2.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon fibers are commonly used in many specialized, high-performance applications such as race cars and aircraft due to their lightweight and high durability. The most important stage in the production of carbon fibers is the carbonization process. During this process, carbon fibers are subjected to high temperatures in the absence of oxygen to prevent fibers from burning. Labyrinth seals are attached to a carbonization furnace to prevent airflow into the furnace and to assist in the elimination of off-gases. This study investigated flow characteristics inside a carbonization furnace and the effects of different geometric parameters of labyrinth seals such as labyrinth tooth shape, number of teeth, and tooth clearance. Varying carbonization furnace operating conditions were also studied in regard to flow behavior, including fiber movement and outlet vacuum pressure. A high working gas flow rate at the furnace inlet resulted in recirculation zones. Properly regulated gas flow from the main and labyrinth inlets enabled uniform flow around the fibers’ inlet and outlet which prevented air from being trapped in the reactor. Flow behavior was minimally effected by changes to labyrinth seal geometry such as tooth length, tooth clearance, and outlet pressure. However, the movement of fibers had a clear effect on flow characteristics in the furnace.
        4,000원
        6.
        2018.11 구독 인증기관·개인회원 무료
        Ovarian folliculogenesis and the production of fertilizable oocytes depend on gap junctional intercellular communication within both the developing and the mature follicle. Gap junctions connect oocytes with granulosa cells and granulosa cells with each other. Various nutritional bio-molecules are known to be transferred to the growing oocyte from the granulosa cells via gap junction. Signals that regulate meiotic maturation of fully-grown oocytes pass through the oocyte-granulosa cell gap junctions. Gap junctions also play a critical role in regulating uterine blood flow, contributing to the maternal recognition and also implantation during pregnancy. Due to the challenge of various stressors the in vitro embryo developmental potentials are still suboptimal compared to in vivo. To identify the molecular mechanism of these stressors and to improve the existing embryo developmental potentials, the singlet oxygens quencher lycopene was added to the culture media to counterbalance the oxidative damage caused by ROS. In this study, we have patterned connexin like Cx43, Cx37, Cx32 and Cx26 at protein and transcription level during follicular growth, atresia and blastocyst stage by using immunohistochemistry, conventional PCR and RT-qPCR. Lycopene (0.2 μM) significantly (P < 0.05) increased the gap junctional communication protein (connexin) expression of Cx43, Cx37, Cx32, Cx26 as compared to the control group at both transcription and translation level during follicular growth, atresia and blastocyst stage. Lycopene potentiates ovarian folliculogenesis, provides the production of fertilizable oocytes and improved embryo developmental capabilities by increasing gap junctional intercellular communication.
        7.
        2018.07 구독 인증기관·개인회원 무료
        The purpose of this study is to assess the role of marketing to the area of strategic alliances. We suggest that marketing capability – the ability to deploy resources to serve customers better- is a key determinant that facilitates value creation in strategic alliances. Specifically, we investigate the interaction effects of marketing capability on performance of strategic alliance experience and types of strategic alliances (introducing three types: SI-SF alliance, AI-SF alliance and AI-DF alliance), and whether these interaction effects are moderated by high vs. low technological industry. This study analyzed the panel data from 39 international firms and their 2,158 alliances during the period 1994 - 2014, 21 firms from computer industry (high-tech industry) and 18 firms from food industry (low-tech industry), respectively. The results indicate that the contribution of marketing capability on the relationships between alliance experience, types of strategic alliances and firm value varies with environmental contexts. First, when a firm has strong marketing capability, the effect of strategic alliance experience on firm value is greater than those of firms with low marketing capability. Also, the strength of its interaction effect is lower in high-tech industry than low-tech industry. Second, when a firm has strong marketing capability, the effects of three different types of strategic alliances on firm value are greater than those of firms with low marketing capability. However, their interaction effects to firm value were significant only in high-tech industry. Specifically, when a firm has strong marketing capability, the stock market reacts most favorably to the AI-DF alliance than those of SI-SF alliance and AI-SF alliance in high-tech industry. In contrast, even a firm has strong marketing capability, the stock market reacts favorably only to AI-SF alliance in low-tech industry. In sum, our research suggests that the interactive performance impact of marketing capability to the strategic alliance experience and the types of strategic alliances can be obtained in particular environmental contexts.
        8.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to examine the influences of two human chorion gonadotrophins (hCGs) being injected into young or aged (45- to 65-week old) outbred (ICR) mice on developmental capacity of oocytes retrieved. In vitro-culture and parthenogenetic activation of oocytes retrieved were employed for the assessment. Superovulation was determined as being induced when more than 25 oocytes were retrieved. No aged mice were superovulated, while in contrast, 67-100% were superovulated in the 6- to 8-week-old (young) mice. In the aged, hCG injection yielded better retrieval (5 vs. 13 to 14.8 oocytes/mouse). Overall, no significant difference between two hCGs was detected but between the young and aged, significant differences in maturational arrest (0% vs. 39% MI arrest and 46% vs. 15% degeneration) and developmental capacity (24% vs. 46% 8-cell embryo development) were detected. In conclusion, hCG injection contributes to increasing oocyte retrieval from aged outbred mice, but the kinds of gonadotrophin influenced the efficiency of hyperstimulation induction in specific ages.
        4,000원
        9.
        2017.05 구독 인증기관·개인회원 무료
        This study investigated the effect of Charcoal:Dextran Stripped fetal bovine serum (CDS FBS) and heat-inactivated FBS (HI FBS) in embryo culture medium on their ability to support in vitro development of bovine embryos. The developmental ability and quality of bovine embryos were determined by assessing their cell number, lipid content, mitochondrial activity, gene expression, and cryo-tolerance. The percentages of embryos that underwent cleavage and formed a blastocyst were significantly (P<0.05) higher in medium containing CDS FBS than in medium containing HI FBS (42.84 ± 0.78% vs. 36.85 ± 0.89%, respectively). Furthermore, the beneficial effects of CDS FBS on embryos were associated with a significantly reduced intracellular lipid content, as identified by Nile red staining, which increased their cryo-tolerance. The post-thaw survival rate of blastocysts was significantly (P<0.05) higher in the CDS FBS than in the HI FBS group (85.33 ± 4.84% vs. 68.67 ± 1.20%). Quantitative real-time PCR showed that the mRNA levels of acyl-CoA synthetase long-chain family member 3, acyl-coenzyme A dehydrogenase long-chain, hydroxymethylglutaryl-CoA reductase, and insulin-like growth factor 2 receptor were significantly increased upon culture with CDS FBS. Moreover, the mRNA levels of sirtuin 1, superoxide dismutase 2, and anti-apoptotic associated gene B-cell lymphoma 2 in frozen-thawed blastocysts were significantly (P<0.05) higher in the CDS FBS group than in the HI FBS group, however, the mRNA level of the pro-apoptotic gene BCL2-associated X protein was significantly reduced. Taken together, these data suggest that supplementation of medium with CDS FBS improves in vitro bovine embryo developmental competence and cryo-tolerance.
        10.
        2016.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the results of BV time-series photometry of the globular cluster NGC 288. Ob- servations were carried out to search for variable stars using the Korea Microlensing Telescope Network (KMTNet) 1.6-m telescopes and a 4k pre-science CCD camera during a test observation from August to December, 2014. We found a new SX Phe star and confirmed twelve previously known variable stars in NGC 288. For the semi-regular variable star V1, we newly determined a period of 37.3 days from light curves spanning 137 days. The light-curve solution of the eclipsing binary V10 indicates that the system is probably a detached system. The pulsation properties of nine SX Phe stars were examined by applying multiple frequency analysis to their light curves. We derived a new Period-Luminosity (P-L) relation, hMV i = −2.476(±0.300) logP − 0.354(±0.385), from six SX Phe stars showing the fundamental mode. Additionally, the period ratios of three SX Phe stars that probably have a double-radial mode were investigated; PFO/PF = 0.779 for V5, PTO/PFO = 0.685 for V9, PSO/PFO = 0.811 for V11. This paper is the first contribution in a series assessing the detections and properties of variable stars in six southern globular clusters with the KMTNet system.
        4,300원
        11.
        2016.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present photometric results of the  Sct star V1162 Ori, which is extensively monitored for a total of 49 nights from mid-December 2014 to early-March 2015. The observations are made with three KMTNet (Korea Microlensing Telescope Network) 1.6 m telescopes installed in Chile, South Africa, and Australia. Multiple frequency analysis is applied to the data and resulted in clear detection of seven frequencies without an alias problem: five known frequencies and two new ones with small amplitudes of 1.2-1.7 mmag. The amplitudes of all but one frequency are significantly different from previous results, confirming the existence of long-term amplitude changes. We examine the variations in pulsation timings of V1162 Ori for about 30 years by using the times of maximum light obtained from our data and collected from the literatures. The O − C (Observed minus Calculated) timing diagram shows a combination of a downward parabolic variation with a period decreasing rate of (1/P)dP/dt = −4.22 × 10−6 year−1 and a cyclic change with a period of about 2780 days. The most probable explanation for this cyclic variation is the light-travel-time effect caused by an unknown binary companion, which has a minimum mass of 0.69 M⊙. V1162 Ori is the first  Sct-type pulsating star of which the observed fast period decrease can be interpreted as an evolutionary effect of a pre-main sequence star, considering its membership of the Orion OB 1c association.
        4,000원
        15.
        2020.12 KCI 등재 서비스 종료(열람 제한)
        Chronological aging and photoaging affect appearance, causing wrinkles, pigmentation, texture changes, and loss of elasticity in the skin. Phragmites communis is a tall perennial herb used for its high nutritional value and for medicinal purposes, such as relief from fever and vomiting and facilitation of diuresis. In this study, we investigated the effects of ethanol extract of P. communis rhizome (PCE) on skin aging. The total flavonoid and total phenolic content in PCE were 2.92 ± 0.007 ㎍ of quercetin equivalents (QE) and 231.8 ± 0.001 ㎍ of gallic acid equivalents (GAE) per 100 ㎎ of dried extract (n = 3). The half-maximal inhibitory concentration (IC50) values of PCE for 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and hydrogen peroxide scavenging activities were 0.96 and 0.97 ㎎/mL, respectively. PCE showed inhibitory effects on tyrosinase when L-tyrosine (IC50 = 1.25 ㎎/mL) and L-3,4-dihydroxyphenylalanine (IC50 = 0.92 ㎎/mL) were used as substrates. PCE treatment up to 200 ㎍/mL for 24 h did not cause any significant cytotoxicity in B16F10 melanocytes, human dermal fibroblasts (HDFs), and HaCaT keratinocytes. In B16F10 melanocytes, PCE (25 and 50 ㎍ /mL) inhibited melanin production and cellular tyrosinase activity after challenge with α-melanocyte-stimulating hormone (α-MSH; p < 0.05). In HDFs, PCE suppressed the mRNA expression of matrix metalloproteinase-1 (MMP-1) and reduced the activity of elastase (p < 0.05). In addition, ultraviolet B (UVB)-mediated downregulation of hyaluronic acid synthase-2 gene expression in HaCaT keratinocytes was also effectively suppressed by PCE treatment. Overall, our results showed that PCE has potential anti-skin aging activity associated with the suppression of hyperpigmentation, wrinkle formation, and reduction in dryness. PCE is a promising candidate for the development of an anti-skin aging cosmetic ingredient.
        16.
        2018.09 KCI 등재 서비스 종료(열람 제한)
        Angelica tenuissima, also known as Ligusticum tenuissimum, is classified as a food-related plant and has been used as traditional medicines treating headache and anemia in Asia. However, its anti-melanogenic effect has not been reported in detail. When the extract of Angelica tenuissima (ATE) was prepared by the extraction with 70% EtOH at 80°C (final yield = 22%), the contents of decursin and Z-ligustilide in ATE were determined 0.06% and 8.43%, respectively. Total flavonoid and phenolic content in mg ATE were 5.52±0.07 ㎍ quercetin equivalents and 237.27±13.24 ㎍ gallic acid equivalents, respectively. Antioxidant capacity of ATE determined by DPPH and ABTS assay was increased with a dose dependent manner up to 1000 ㎍/㎖. The amount of melanin synthesis followed by α-melanocyte stimulating hormone on B16F10 cells were significantly reduced in the presence of ATE (250 to 1000 ㎍/㎖, p<0.05). ATE (125 to 1000 ㎍/㎖, p<0.05) suppressed the tyrosinase activity but did not show any significant effect on α-glucosidase activity at the same condition. Taken together, ATE possesses tyrosinase inhibitory potential with significant antioxidant capacities. These effects of ATE might be involved in suppression of melanin synthesis, at least, in B16F10 cells. The anti-melanogenic potential of ATE will provide an insight into developing a new skin whitening product.
        17.
        2015.07 서비스 종료(열람 제한)
        The β-carotene biofortified transgenic soybean was developed recently through Agrobacterium -mediated transformation using the recombinant PAC (Phytoene synthase-2A-Carotene desaturase) gene in Korean soybean (Glycine max L. cv. Kwangan). GM crops prior to use as food or release into the environment required risk assessments to environment and human health in Korea. Generally, transgenic plants containing a copy of T-DNA were used for stable expression of desirable trait gene in risk assessments. Also, information about integration site of T-DNA can be used to test the hypothesis that the inserted DNA does not trigger production of unintended transgenic proteins, or disrupt plant genes, which may cause the transgenic crop to be harmful. As these reasons, we selected four transgenic soybean lines expressing carotenoid biosynthesis genes with a copy of T-DNA by using Southern blot analysis, and analyzed the integration sites of their T-DNA by using flanking sequence analysis. The results showed that, T-DNA of three transgenic soybean lines (7-1-1-1, 9-1-2, 10-10-1) was inserted within intergenic region of the soybean chromosome, while T-DNA of a transgenic soybean line (10-19-1) located exon region of chromosome 13. This data of integration site and flanking sequences is useful for the biosafety assessment and for the identification of the β-carotene biofortified transgenic soybean.
        18.
        2015.07 서비스 종료(열람 제한)
        A variety of genetically modified (GM) crops have been developed in Korea. In these crops, the resveratrol-enriched transgenic rice plant has moved ahead to generate the dossier for regulatory review process required for commercialization of GM crop. The resveratrol-enriched transgenic rice plant could be released to farmers for cultivation after national regulators have determined that it is safe for the environment and human health. Here we developed a PCR-based DNA marker based on flanking sequences of transgene for the discrimination of zygosity in resveratrol-enriched transgenic rice plant. This DNA marker will be useful for identifying of resveratrol-enriched transgenic rice plant, and can also be use to estimate transgene movement occurred by pollen transfer or seed distribution.
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