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        검색결과 364

        2.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Despite enormous popularity of graphene oxide (GO) several open questions remain regarding the structure and properties of this material. One of those questions is the role of a graphite precursor on the properties of GO product. In this study, we investigate the oxidation process and the structure of GO products, made from the four different graphite precursors: synthetic graphite, two natural flaky graphites, and expanded graphite. The highest rate of the oxidation reaction was registered for the small particle size synthetic graphite. Thermal expansion of natural flaky graphite did not significantly affect the rate of the reaction. The nature of the graphite precursor does not notably affect the chemical composition of the synthesized GO products. However, it affects stability of respective aqueous dispersions. The solutions of the three GO samples, prepared from the natural graphite sources demonstrate excellent stability due to complete exfoliation of GO to single-atomic-layer sheets. GO from synthetic graphite forms unstable dispersions due to the presence of numerous multi-layered particles. This, in turn, is explained by the presence of not fully graphitized, amorphous inclusions in synthetic graphite. Our observations suggest that synthetic graphite should not be used as GO precursor when the ability to completely exfoliate and the stability of dispersions are critical for intended applications.
        4,000원
        3.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Porcine embryonic development is widely utilized in the medical industry. However, the blastocyst development rate in vitro is lower compared to in vivo . To address this issue, various supplements are employed. Extracellular vesicles (EVs) play the role of communicators that carry many bioactive cargoes. Additionally, the contents of EVs can vary on the estrous cycle. Methods: We compared the effects of adding EVs derived from porcine uterine fluid (UF), categorized as non-EV (G1), EVs in estrus (G2) and EVs in diestrus (G3). After in vitro culture (IVC) was performed in three different groups, cleavage rate and blastocyst development rate were examined. In addition, glutathione (GSH) and reactive oxygen species (ROS) levels were measured 2 days after activation to assess oxidative stress. Results: Using NTA and cryo-TEM, we confirmed the presence of EVs with sizes ranging from 30 nm to 200 nm, that the particles were suitable for analysis for analysis. In IVC data, the highest cleavage rate was observed in G2, which was significantly different from G1 but not significantly different from the next highest, G3. Similarly, the highest blastocyst development rate was observed in G2, which was significantly different from G1 but not significantly different from the next highest, G3. Conclusions: These results indicate that estrus derived EVs contain biofactors beneficial for early blastocyst development, including GSH which protects the blastocyst from oxidative stress. Additionally, although diestrus-derived EVs are expected to have some effect on blastocyst development, it appeared to be less effective than estrus-derived EVs.
        4,000원
        5.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        New tetrazole fused imidazopyridine derivatives (12a–j) were developed to exploit their cytotoxic activity towards cancer cell lines-MCF7, A549, and MDA-MB-231, utilizing MTT reduction assay with doxorubicin as standard drug. The compounds 12 h and 12j demonstrated strong anticancer activity bearing IC50 values 1.44 μM and 1.33 μM against A549 cell line.
        4,000원
        6.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hypertension is characterized by excessive renin-angiotensin system activity, leading to blood vessel constriction. Several synthetic compounds have been developed to inhibit renin and angiotensin-converting enzyme (ACE). These drugs often have adverse side effects, driving the exploration of plant protein-derived peptides as alternative or supplementary treatments. This study assessed the phenolic compound and amino acid content and the antioxidant and antihypertensive activity of 5 South Korean staple crops. Sorghum had the highest phenolic compound content and exhibited the highest antioxidant activity. Millet grains, particularly finger millet (38.86%), showed higher antihypertensive activity than red beans (14.42%) and sorghum (17.16%). Finger millet was found to contain a large proportion of branched-chain, aromatic, and sulfur-containing amino acids, which are associated with ACE inhibition. In particular, cysteine content was positively correlated with ACE inhibition in the crops tested (r=0.696, p<0.01). This study confirmed that the amino acid composition was more correlated with the antihypertensive activity of grains than the phenolic compound content. Finger millet mainly contained amino acids, which have higher ACE inhibitory activity, resulting in the strongest antihypertensive activity. These findings underscore the antihypertensive potential of select crops as plant-based food ingredients, offering insight into their biological functions.
        4,200원
        7.
        2023.10 구독 인증기관·개인회원 무료
        Miridae show remarkable diversity (>11,700 spp.), accounting for a quarter of all Heteroptera. However, their phylogeny and evolutional history is still remain unclear. In this work, we provide new suggestions for the phylogeny of Miridae using a larger dataset than previous studies. In addition, we suggest an alternative evolutionary history based on newly calibrated divergence dates for Miridae and its subordinate groups, and present probable factors of the family’s success in terms of species diversity. The entire dataset comprises 16 outgroups and 188 ingroup taxa including all seven known subfamilies and 37 out of 45 known tribes. Each species is aligned as 3,577 bp with six molecular loci (COI, 16S rRNA, 18S rRNA, 28S rRNA D3 region, H2A, and H3A).
        8.
        2023.10 구독 인증기관·개인회원 무료
        Many insects form mutualistic relationships with microbial symbionts, crucial for their physiological processes. The bean bug, Riptortus pedestris, establishes a unique gut symbiosis with the genus Caballeronia and consistently acquires these symbionts from surrounding soil with each generation. As a result, the bean bug unavoidably consumes a variety of environmental microbes, including potential pathogens. To address this, the bean bug has developed a specialized organ in its midgut that selectively filters out non-symbiotic microbes, thereby preventing contamination of its symbiotic organ. In this study, we identified a pathogenic strain from the genus Burkholderia that lethally affects the bean bug post-invasion of the symbiotic organ. This pathogen employs a strategy of mimicking the motility of native symbionts to infiltrate the symbiont sorting organ and displays a pronounced resistance against antimicrobial agents produced by the host. Upon establishing itself in the symbiotic organ, the pathogen breaches the midgut cells, leading to host mortality, and subsequently disperses into the external environment. Our findings unveil a cunning pathogenic tactic that exploits the mimicry of native symbionts within an insect's symbiotic framework.
        10.
        2023.07 구독 인증기관·개인회원 무료
        Innovative companies after the first and second waves of the COVID-19 pandemic are undergoing significant changes: from new trends in the markets to the growth of remote work in the digital environment. At any stage of development, innovative companies need an adaptive marketing approach to the implementation of the planned strategy. Marketing solutions to the problems of a volatile, uncertain, complex and ambiguous environment (VUCA) in 2023 can rightfully be considered an emergency aid to innovative transformations in emerging markets. The triad “market orientation – innovation – performance” chain has been extended to various innovation types– from technological and product innovation to innovation orientation and capability. Moreover, the market orientation research agenda has, during last 10 years, highlighted customer orientation as a key component of market orientation that drives innovative activities.
        11.
        2023.07 구독 인증기관·개인회원 무료
        Many retailers and food service providers offer programs as part of their loyalty programs in which customers are given stamps for each purchase of a qualifying product or service and redeemed for a reward once a certain number of stamps have been accumulated. We identify which stimuli in such goal-directed motivational promotions induce customers to participate in the program.
        12.
        2023.07 구독 인증기관·개인회원 무료
        Negative brand events can significantly harm the brand, affecting consumer cognitions, emotions, and behavior, leading to negative brand evaluations, negative emotions, brand avoidance, and retaliation. Thus, it is critical for brands to design and implement strategies that promote consumer forgiveness to mitigate those negative consumer responses. Despite the growing literature on the determinant factors of consumer behavior in a brand failure context, there is still scarce evidence regarding the impact of brand type on consumer responses, including consumer forgiveness, following a negative brand event. Considering that consumers tend to react differently to a brand perceived as arrogant (making them feel inferior), as opposed to a brand they strongly identify with, this paper focuses on failures of equal vs. higher status brands and investigates their impact on consumer forgiveness. Following the above, we expect that differences in brand status can shape consumer behavior following a failure or transgression.
        13.
        2023.07 구독 인증기관·개인회원 무료
        Following the military advance of Russian forces into Ukraine in February 2022, Russia became the most sanctioned country in the world (Shapiro, 2022) as global leaders attempted to condemn the act and impose several sanctions on the Russian Federation including the ban of Russian oil and gas imports, the closure of airspace to Russian airplanes and the removal of Russian banks from the Swift international payment network (BBC, 2022). Among the noticeable effects of the Russia-Ukraine conflict is the animosity expressed against Russians. In a marketing context, animosity has been studied mostly from the perspective of consumers and is conceptualized as the “anger related to previous or ongoing military, economic or diplomatic events” (Klein et al., 1998:90) which impacts purchasing behaviour. Given that animosity has been found to have enduring effects, it is worth examining the anti-Russian sentiments currently manifesting as these may have impacts in terms of tourism management and marketing.
        14.
        2023.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Wide-Angle Polarimetric Camera (PolCam) is installed on the Korea’s lunar orbiter, Danuri, which launched on August 5, 2022. The mission objectives of PolCam are to construct photometric maps at a wavelength of 336 nm and polarization maps at 461 and 748 nm, with a phase angle range of 0◦–135◦ and a spatial resolution of less than 100 m. PolCam is an imager using the push-broom method and has two cameras, Cam 1 and Cam 2, with a viewing angle of 45◦ to the right and left of the spacecraft’s direction of orbit. We conducted performance tests in a laboratory setting before installing PolCam’s flight model on the spacecraft. We analyzed the CCD’s dark current, flat-field frame, spot size, and light flux. The dark current was obtained during thermal / vacuum test with various temperatures and the flat-field frame data was also obtained with an integrating sphere and tungsten light bulb. We describe the calibration method and results in this study.
        4,000원
        15.
        2023.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The GMT-Consortium Large Earth Finder (G-CLEF) is the first instrument for the Giant Magellan Telescope (GMT). G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. G-CLEF Flexure Control Camera (FCC) is included as a part in G-CLEF Front End Assembly (GCFEA), which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within GCFEA. FCC consists of an optical bench on which five optical components are installed. The order of the optical train is: a collimator, neutral density filters, a focus analyzer, a reimager and a detector (Andor iKon-L 936 CCD camera). The collimator consists of a triplet lens and receives the beam reflected by a fiber mirror. The neutral density filters make it possible a broad range star brightness as a target or a guide. The focus analyzer is used to measure a focus offset. The reimager focuses the beam from the collimator onto the CCD detector focal plane. The detector module includes a linear translator and a field de-rotator. We performed thermoelastic stress analysis for lenses and their mounts to confirm the physical safety of the lens materials. We also conducted the global structure analysis for various gravitational orientations to verify the image stability requirement during the operation of the telescope and the instrument. In this article, we present the opto-mechanical detailed design of G-CLEF FCC and describe the consequence of the numerical finite element analyses for the design.
        5,100원
        18.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 제주특별자치도에 유입된 Myocastor coypus Molina, 1782 (Nutria)의 퇴치를 위해 이루어졌다. 서식확인 및 퇴치는 2013년 9월부터 2013년 11월까지 이루어졌고, 그후 퇴치 성공여부를 확인하기 위해 2022년 6월까지 조사가 이루어졌다. 서식 확인 및 포획은 무인카메라, 청문조사, 문헌조사, 먹이유인을 통한 트랩 포획법을 사용하여 진행하였다. 후속조사는 Nutria의 행동반경을 감안하여 조사범위를 비교적 넓게 설정하여 서식지역(퇴치지역)을 중심으로 4.0㎢ 내 습지 및 하천 조사를 진행하였다. 그 결과 서식 확인지역은 제주특별자치도 제주시 구좌읍 송당리 소재의 송당목장에 서만 발견되었으며, 방목장 내 수로와 연못에서 서식흔적(족적, 배설물, 굴)이 확인되었다. 포획개체는 총 8개체였으며, 암컷 4개체, 수컷 3개체였다. 1개체는 서식확인 시 확인되어 부패 정도가 심해 암·수의 구별이 어려웠다. 후속조사는 설정한 조사범위 내 항시 물이 있는 성읍저수지, 천미천, 몰순이못을 중심으로 서식지와 그 주변을 정밀조사하였으나 서식흔적이 확인되지 않았다. 따라서, 제주도에 서식하는 Nutria는 완전히 퇴치된 것으로 판단된다. 제주특별자치도에서 Nutria의 퇴치가 성공적으로 이루어진 것은 Nutria의 서식 확인 후 빠른 포획을 통해 정착단계 초기에 퇴치가 이루진 것과 제주도 지질 특성상 물이 항시 고여있는 습지가 드물어 확장의 시기가 늦어진 것이 시너지 효과를 일으켜 성공적인 퇴치가 이루어진 것으로 판단된다. 이 결과들은 외래종의 유입에 대한 대처는 그 종의 생태특성을 신속하게 파악하고, 올바른 대처를 통해 확장단계 이전 정착 초기 단계에서 관리 및 퇴치를 통해 교란이 일어나기 전 또는 교란 초기에 차단하는 것이 매우 효과적인 방법임을 시사한다.
        4,000원
        19.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 집쥐 퇴치 계획은 대한민국 최대 슴새 번식지 및 흑비둘기 서식처로 천연기념물 제333호로 지정되어있는 제주특별 자치도 소재(33°55′13.04″N, 126°38′19.98″E) 무인도서인 사수도 내 집쥐 퇴치를 위해 이루어졌다. 구제 연구는 2015년 11월부터 2021년 2월까지 총 12차례 진행되었고, 조사는 섬 전역을 천천히 배회하며 출발지점과 도착지점을 동일하게 하여 조사하는 선조사법을 이용하였다. 이 때 확인된 배설물, 터널 등 Rattus norvegicus 흔적 주변에 포획트랩 을 설치하였다. 그 결과 매 차시 최소 2개체 ~ 최대 6개체가 포획되던 개체가 마지막에는 포획되지 않았다. 집쥐가 사수도에 유입된 경로는 과거 레저 및 어업을 위해 출입하는 배를 통하여 유입되었을 것으로 추정하고 있다. 2006년 집쥐로 인한 슴새의 피해가 확인된 후 철저한 경비를 통하여 사수도 출입을 엄격히 금하고 2013년 해양정화 사업과 2015년부터 지속된 포획을 통하여 구제가 성공적으로 이루어지고 있는 것으로 판단된다. 본 상태 유지 및 관리를 위해서 앞으로 새로운 집쥐의 유입을 제어하기 위하여 지속적이고 철저한 출입관리를 이어가 출입자를 엄격히 통제하는 등의 보존 관리방안이 필요하다 할 수 있다.
        4,000원
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