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        검색결과 49

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Aflatoxin B1 (AFB1) is a toxic metabolite generated by Aspergillus species and is commonly detected during the processing and storage of food; it is considered a group I carcinogen. The hepatotoxic effects, diseases, and mechanisms induced by AFB1 owing to chronic or acute exposure are well documented; however, there is a lack of research on its effects on the intestine, which is a crucial organ in the digestive process. Dogs are often susceptible to chronic AFB1 exposure owing to lack of variation in their diet, unlike humans, thereby rendering them prone to its effects. Therefore, we investigated the effects of AFB1 on canine small intestinal epithelial primary cells (CSIc). Methods: We treated CSIc with various concentrations of AFB1 (0, 1.25, 2.5, 5, 10, 20, 40, and 80 μM) for 24 h and analyzed cell viability and transepithelial-transendothelial electrical resistance (TEER) value. Additionally, we analyzed the mRNA expression of tight junction-related genes (OCLN, CLDN3, TJP1, and MUC2), antioxidant-related genes (CAT and GPX1), and apoptosis-related genes (BCL2, Bax, and TP53). Results: We found a significant decrease in CSIc viability and TEER values after treatment with AFB1 at concentrations of 20 μM or higher. Quantitative polymerase chain reaction analysis indicated a downregulation of OCLN, CLDN3, and TJP1 in CSIc treated with 20 μM or higher concentrations of AFB1. Additionally, AFB1 treatment downregulated CAT , GPX1, and BCL2. Conclusions: Acute exposure of CSIc to AFB1 induces toxicity, and exposure to AFB1 above a certain threshold compromises the barrier integrity of CSIc.
        4,000원
        2.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbon (AC) is a versatile and extensively employed adsorbent in environmental remediation. It possesses distinct properties that can be enhanced to selectively target specific pollutants through modifications, including chemical impregnation or incorporation into composite materials. In this study, porous calcium alginate beads (PCAB) were synthesized by incorporating AC and natural alginate through ion gelation in a Ca(II) ion-containing solution, with the addition of sodium lauryl sulfate as a surfactant. The prepared PCAB was tested for Cu(II) removal. PCAB exhibited a spherical shape with higher porosity and surface area (160.19 m2. g−1) compared to calcium alginate beads (CAB) (0.04 m2. g−1). The adsorption kinetics followed the pseudo-first-order model for PCAB and the pseudo-second-order model for CAB. The Langmuir isotherm model provided the best fit for adsorption on PCAB, while the Freundlich model was suitable for CAB. Notably, PCAB demonstrated a maximum adsorption capacity of 75.54 mg.g−1, significantly higher than CAB's capacity of 9.16 mg. g−1. Desorption studies demonstrated that 0.1 M CaCl2 exhibited the highest efficiency (90%) in desorbing Cu(II) ions from PCAB, followed by 0.1 M HCl and 0.1 M NaCl. PCAB showed efficient reusability for up to four consecutive adsorption– desorption cycles. The fixed-bed column experiment confirmed the match with the Thomas model to the breakthrough curves with qTH of 120.12 mg.g−1 and 68.03 mg.g−1 at a flow rate of 1 mL.min−1 and 2 mL.min−1, respectively. This study indicated that PCAB could be an effective adsorbent for Cu(II) removal, offering insights for further application and design considerations.
        4,600원
        3.
        2020.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 ‘설향’ 딸기의 수확시기에 따른 품질 특성을 확인하고, 상온(20°C )·cold-chain(10-12°C)·저온 (5°C) 유통에 적합한 숙성단계를 조사하기 위하여 수행하였다. 딸기는 12월 20일부터 5월 9일까지 6번에 걸쳐서 수확하였다. 딸기를 수확할 때 적합한 숙성 정도는 3월까지는 경도 2.9-3.0 N, 당도 8.6 °Brix 이상이었으나, 4월 이후에는 당도가 감소하였다. 딸기의 숙성을 결정하는 주요 요인은 붉게 착색된 정도이고, Hunter a 값은 32-37, hue angle은 36-45°였다. 딸기의 후숙 실험에서 숙성 정도는 딸기의 착색이 진행되는 정도에 따라서 결정되었으며, 상온에서는 10%/day, 10-12°C에서는 5%/day, 5°C에서는 3%/day씩 착색이 진행되었다. 따라서 상온에서 유통할 경우에는 80%, cold-chain · 저온에서 유통하기 위해서는 90%의 착색된 과실을 수확하여야 유통하는 동안 상품성이 유지되었다. 그리고 상온에서는 70% 이하로 착색된 딸기를 유통하거나, 저온에서는 80% 이하로 착색된 딸기를 유통하는 경우에는 100% 착색이 이루어지지 않고 상품성을 잃었다.
        4,200원
        4.
        2018.07 구독 인증기관·개인회원 무료
        People prefer a certain gain over an uncertain one (e.g., Kahneman and Tversky 1979; Gneezy, List, and Wu 2006), and uncertainty threatens the perception of personal control (e.g., Simonsohn 2009; Sonsino 2008; Gaucher, Hafer, Kay, & Davidenko, 2010). Nevertheless, research has also showed that under certain circumstances people love uncertainties as “surprises” can add unexpected pleasures to our life (Goldsmith and Amir 2010; Shen, Fishbach, and Hsee 2015). In this research, we examine consumers’ preference for surprise in the subscription services. A typical subscription business offers a “surprise-me” option, where customers receive the package without knowing what items are included, in addition to (or instead of) customers making their own selections (referred to as the “self-selection” option hereafter). Despite the surging popularity of this business model, little is known whether consumers prefer making their own selections or are willingly let providers surprise them. Theoretically, it offers an opportunity to examine consumers’ willingness to relent their control in choice when there are risks involved. Managerially, answers to these questions can help service providers better design the surprise-me option for both operational efficiencies and customer satisfactions. Our key hypothesis is that a sense of personal control is an important condition for consumers’ preference of the surprise-me option in subscription services. Feeling of control serves as a safeguard and thus allows consumers to attend to the pleasures of uncertainty. This also means that in situations where consumers do not feel in control, their preference for the surprise-me option decreases (relative to the in-control condition). This is because, the compensatory control theory (Whitson & Galinsky, 2008; Kay et al., 2008; 2009) suggests that when consumers feel not in control, they tend to compensate by trying to take things into their own hands (e.g., self-select) to regain control rather than relenting control to others (e.g., to be surprised). However, when it is difficult to regain control through self-selection due to choice difficulty (e.g., lack of topical knowledge), they may again prefer surprise as a way to simply delegate the choice (Aggarwal and Mazumdar 2008; Steffel and Williams 2017). Thus, we expect feeling of control to play an important role in preference of a surprise-me option. We conducted three studies to test this prediction. Overall, the set of studies supported the expected important role of feeling of control. The surprise option is valued only when consumers do not lack the sense of control hence do not need to regain it through choice or the chance of regaining control through choice is low due to choice difficulty (expertise or product assortment characteristics). Our research provides important theoretical contributions.
        5.
        2017.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        리더십 발현과정에는 사회·문화적 맥락으로 인해 차이가 발생할 수 있으나, 국내에서 수행된 다수의 리더십 연구에서는 이러한 특징을 고려하는데 한계가 있다. 이러한 원인은 연구대상을 한국인으로 국한 하기 때문으로 판단된다. 이에 본 연구에서는 한국인과 중국인을 연구대상으로 설정하여 리더십 영향력 과정에서 나타나는 차이를 실증적으로 비교하고자 하였다. 이를 위해, 임파워링 리더십, 기본심리욕구, 선 제적 행동을 연구의 주요 개념으로 설정하였다. 구체적으로 임파워링 리더십의 기본심리욕구(자율성, 관 계성, 유능성 욕구)에 대한 영향력을 확인하고, 기본심리욕구의 선제적 행동(피드백 추구행동, 발언행동) 에 대한 영향력 관계를 설정하였다. 다음으로 임파워링 리더십과 선제적 행동(피드백 추구행동, 발언행 동)의 관계에서 기본심리욕구(자율성, 관계성, 유능성 욕구)의 매개효과를 검증하고자 하였다. 연구목적을 달성하기 위한 자료는 번역타당성 검증과정을 거쳐 설문지를 완성하였으며, 한국인과 중국인으로부터 수 집하였다. 연구대상별 총 330부의 설문지를 배부하여 회수된 자료 가운데 불성실하게 응답한 자료를 제외 하고, 한국인 303명, 중국인 301명으로부터 획득된 자료를 분석하였다. 가설검증을 위한 과정에서 측정도 구의 타당성과 신뢰성은 연구대상을 통합하여 분석을 수행하였으며, 상관관계 및 가설검증은 연구대상을 분리하였다. 연구결과를 정리하면, 임파워링 리더십의 기본심리욕구 만족에 대한 영향력, 기본심리욕구 만족의 선제적 행동에 대한 영향력, 기본심리욕구 만족의 매개효과 경로에서 연구대상에 따른 차이가 확 인되었다. 이러한 결과는 글로벌 경영환경에서 임파워링 리더십을 발휘하는 경우 추종자의 국적에 따른 차이를 고려한 접근을 제안하고 있으며, 기본심리욕구 만족에 있어 임파워링 리더십의 역할을 확인하는 계기를 제공하고 있다.
        6,700원
        6.
        2017.05 구독 인증기관·개인회원 무료
        The mesenchymal stem cells (MSC) has been investigated as a source of stem cell therapy to replace and treat damaged cells. Human endometrial epithelial and stromal cells was isolated from hysterectomy tissue and the direct evidence of stem/progenitor cells in the human endometrium was identified. Endometrium derived stem cells (EnMSCs) are known to have a high proliferative ability, genetic stability, lack of tumorigenicity and low immnunogenicity during long-term cultivation. Here, we aimed to identify MSC in canine endometrium and characterize its potential to differentiate into decidua cells. EnMSCs were isolated from thrown-away spayed uterus of adult canine depending on their estrus cycle, and identified by flow cytometry, immunocytochemistry and flow cytometry with MSC specific markers. We then characterized the ability of EnMSCs by the doubling-time analysis, colony-forming units and MSC differentiation assays. Isolated EnMSCs expressed stem cell specific genes (Sox2, Oct4, Nanog, MCAM, Endoglin, Susd2 and IGTB) and MSC surface markers (CD90, CD44 and CD117). EnMSCs are also differentiated into adipogenic, osteogenic and chondrogenic cells morphologically under modified conditions with the expression of lineage specific genetic markers. EnMSCs showed higher proliferation ability than canine amniotic fluid derived MSCs which were used as a positive control. EnMSCs were cultured at low density (10, 20, cells/cm2) and initiated to form small colonies of loosely-arranged cells and gradually formed large colonies of densely-packed cells which underwent self-renewal with high proliferative potential which is similar to the clonogenicity feature of human endometrium-derived stem cells. EnMSCs were then induced to differentiate into decidua cells with 0.5 mM dbcAMP. After 14 days, EnMSCs changed their morphology into the elongated and rounded shape. The induced decidual cells expressed PRL and IGFBP1 which are typically expressed in decidua cells. In conclusion, we successfully isolated and characterized MSC in the canine endometrium which differentiated into decidua cells. These results showed that endometrium may be a promising source of stem cells, and furthermore raise the possibility of canine EnMSCs as a novel hypothetical decidualisation model of infertility associated with decidualisation insufficiency and implantation failure.
        7.
        2016.10 구독 인증기관·개인회원 무료
        Somatic cell nuclear transfer (SCNT) has been considered for preserving genetically valuable or endangered animals. Sapsaree is a Natianal Monument in Korea to maintian a pure pedigree. The aim of this study was to produce azoospermia Sapsaree using SCNT and identify normal reproductive ability of cloned azoospermia Sapsaree. Ear skin biopsy was performed on a thirteen-year-old azoospermia Sapsaree and ear skin fibroblasts were isolated for SCNT as donor cells. The fibroblasts were injected into enucleated in vivo matured oocytes, the couplets were electrical fused by two pulse of direct current (55 V for 15 μs) using titanium and platinum fusion needle and activated by calcium ionophore. Cloned embryos were surgically transferred into oviducts of natuarally estrus cycle synchronized recipient dogs. The fusion rate of platinum needle was 70%, which was higher than those of titanium needle (64.1%). Developmental rate to the 8 cells and 10 cell stages was higher in platinum needle group (24% and 16%, respectively) than those of platinum needle group (14.8% and 3.1%, respectively). Total 35 SCNT embryos were transferred into oviducts of 3 recipient dogs and one recipient finally delivered a puppy by caesarean section. As results, this study demonstrated that platinum fusion needle could be successfully make the reconstructed embryos and improve the efficiency of canine SCNT. Cloning azoospermia Sapsaree may contribute to conserve genetically valuable and unique pedigree. And further study should be confirm whether cloned live dog is azoospermia.
        8.
        2016.10 구독 인증기관·개인회원 무료
        Prolonged communication between oocytes and the surrounding somatic cells is one of the unique reproductive physiology in canine. Paracrine Kit ligand (KITL) signaling is a well-known communication between granulosa cells and the oocyte. KITL is a cytokine growth factor secreted by granulosa cells that signals via the c-kit receptor expressed by oocytes. Paracrine factors, including growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), exert their effects by binding with the kinase receptors expressed on the granulosa cells. However, the regulations of GDF9 and BMP15 in the canine KITL expression are currently poorly understood. Therefore, we investigated the effects of GDF9 and BMP15 on the expression of KITL in canine ovarian granulosa cells in vitro. In Annexin V assay recombinant GDF9 and BMP15 did not induce apoptosis in the cultured ovarian granulosa cells. When treated, FSH significantly increased KITL expression, and hCG suppressed its expression. When both FSH and hCG were treated, the expression of KITL was affected by GDF9 and BMP15 in dose and time dependent manner in the luteal granulosa cells. GDF9 (10 ng/mL) significantly decreased KITL expression after12 h. BMP15 (10 ng/mL) significantly also decreased KITL expression after 24 h. Western blot and immunochemistry results indicate that GDF9 activated Smad2/3. After blocking ALK 4/5/7 receptors by SB, GDF9 failed to activate Smad2/3, also BMP15 did not activate Smad1/5/8 after blocking ALK 2/3/6 receptors by DM. So GDF9 exerts its effects via using ALK 4/5/7 receptors to activate SMAD2/3 signaling, and BMP15 binds ALK 2/3/6 receptors to activate SMAD1/5/8 signaling. The expression of KITL was not changed by SB or DM treatment. However, the effect of GDF9 and BMP15, which decreased the expression of KITL, was suppressed by SB or DM treatment. In conclusion, this study provides the first evidence that recombinant GDF9 and BMP15 decrease KITL expression in canine ovarian granulosa cells.
        9.
        2016.10 구독 인증기관·개인회원 무료
        The cancer and Parkinson's disease associated protein DJ-1 is multifunctional protein that involves in diverse cellular process. DJ-1 protein has a cellular protective role and promoted cell survival under an oxidative stress. However, the cellular protective mechanism of DJ-1 is not fully understand, and we needs to be further study their functions in novel organisms. In the present study, we investigated the protective role of DJ-1 against induced oxidative stress in canine cell line. On the basis of these experiments, canine DJ-1 overexpressing and null cell lines were established. The stable overexpression and down regulation of DJ-1 efficiency confirmed by the western blot analysis. Subsequently, the DJ-1 gene transfected cell lines and control cells were subjected to induced the oxidative stress, and then cell viability, cell proliferation assay, cellular apoptosis detection analysis (Annexin V and TUNEL assay), intracellular ROS and mitochondrial activity were measured appropriately. The results showed that DJ-1 overexpressed cells were up-regulated cell viability under oxidative stress conditions induced by the rotenone and hydrogen peroxide (H2O2), whereas loss of DJ-1 cells were down-regulated the cell survival activity. Additionally, overexpression of DJ-1 cells increased cell resistance to oxidative stress and inhibited the elevation of cell death and cellular ROS induced apoptosis. Moreover, DJ-1 overexpressed cells was increased mitochondrial functions by using confocal microscopy with MitoTracker staining. On the contrary to this, DJ-1 null cells show defective cellular protection and mitochondria activity against oxidative stress conditions. Our data indicate that canine DJ-1 protein attenuates cellular apoptosis and ROS generation, enhances the cellular survival activity and promote mitochondrial function under the oxidative stress, likewise other mammalian cells. Importantly, DJ-1 overexpression may be an important part of a protective strategy as a sensor for oxidative stress.
        11.
        2009.08 구독 인증기관·개인회원 무료
        Thee kinds of explants, young spikes, immature and mature embryos, was compared in callus induction, embryogenic callus formation, differentiation and plant regeneration of Russian wildrye. Callus induction efficient of young spikes is highest. The imature embryos formed more somatic embryogenesis, and with highest frequency of embryogenic callus.
        12.
        2009.03 구독 인증기관 무료, 개인회원 유료
        A improved strength model was developed to predict the punching shear strength of interior slab-column connections without shear reinforcement. Considering the damage due to flexural cracking at slab-column connections damaged by flexural cracking, the punchingshear force was assumed to be resisted mainly by the compression zone of the critical section. The punching shear strength was defined by using the material failure criteria of concrete. In the evaluation of the punching shear strength, the interaction between the shear stress and the compressive normal stress developed by the flexural moment of the slab was considered. The proposed strength model was verified by existing test specimens.
        4,000원
        13.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Petroleum pitch and coke with wet mixture method or with dry mixture method were investigated to develop the composite anodic carbon material of high power lithium ion battery. Cokes coated with pitch were obtained by the heat treatment of mixture of cokes and pitch with different weight ratios at 800~1200℃. The charge and discharge characteristic of the consequent composite anodic carbon material assembled in batteries was tested. Cokes with wet mixture method have a smooth surface and their capacity changed little with changing temperature and content as compared to the cokes with dry mixture method. Although the reversible capacities showed different values by the anode manufacturing method, the composite anode with the mixture of 20 wt% of petroleum pitch and 80 wt% of coke showed the higher power capability and initial efficiency than the pitch based anode. However, the reversible capacity of the composite anode showed the reduced value as compared with the pitch based anode.
        4,000원
        14.
        2008.03 구독 인증기관 무료, 개인회원 유료
        In this study, based on the results from the sinusoidal base excitation analyses of a single degree of freedom system with a tuned mass damper (TMD) , the optimal friction is computed so that the rail friction improve the performance of the TMD. The magnitude of the optimal friction increases with increasing mass ratio of the TMD and decreases with increasing structural damping. Particularly, it is observed that the optimized friction force gives better control performance than the optimized viscous damping of the TMD. However, because the performance of the TMD considerably deteriorates when the friction force increases over the optimal value, it is required to keep the friction force from exceeding the optimal value. Based on the results from this study, it is possible to economically design the TMD by avoiding the unconditional minimization of the rail friction and in some cases by removing the additional damping devices of which function can be performed by the rail friction.
        4,000원
        15.
        2006.09 구독 인증기관 무료, 개인회원 유료
        This paper presents vibration control of a real-scaled five-story steel structure subjected to horizontal excitation using a semi-active magneto-rheological (MR) damper. A large-sized double-rod MR damper, which is applicable for vibration control of the real-scaled five-story structure, is designed and manufactured on the basis of the field-dependent Bingham model of the MR fluid. The damping force of the MR damper is experimentally evaluated with respect to the excitation frequency at various magnetic fields. After formulating the governing equation of motion for the five-story structure associated with the MR damper, displacement and acceleration responses of the structure are discussed under pseudo earthquake excitation in which a hybrid mass damper is designed to reproduce seismically excited structural responses. The controllers which require only structural response of the damper installed floor for calculating the input current of the MR damper are designed to effectively suppress unwanted structural vibrations
        3,000원
        16.
        2006.04 구독 인증기관·개인회원 무료
        This paper concerned with SPS (spark plasma sintering), hot pressing of sinter nanometer WC-Co powder and discussed the density, hardness, microstructures and grain sizes of the alloys sintered. The results showed that the two sintered techniques could produce high density alloys and play well on the grain growth, but SPS could lower the sintering temperature and shorten sintering time. Besides, the hardness of the sintered cemented alloys that was dependent on the grain size and densification could also be improved.
        17.
        2006.02 구독 인증기관 무료, 개인회원 유료
        Corrosion level of reinforcing bar is investigated in this study. Seventy-two specimens are designed with 12 different target corrosion levels, two types of reinforcing bars, 3 different concrete covers. Corrosion current density, corrosion potential and ohmic resistance of concrete are measured on these specimens using Gecor device. Metal loss measurements are performed in accordance with ASTM G1-90[1], method C3.5[2], after specimens cracked. The actual corrosion weight loss of the steel reinforcing bars is then compared to the result obtained from the corrosion level measurement. Finally, the estimation of corrosion level can be made using electrical potential and current intensity measured. The experimental results show that the actual corrosion levels of steel bars embedded in concrete are less than the expected corrosion levels. And non-destructive corrosion measurement technique is applicable in order to assess corrosion level in reinforcing bars. This study suggests the relationship between corrosion level and measured electrical potential and measured current intensity.
        4,000원
        18.
        2004.02 구독 인증기관 무료, 개인회원 유료
        Corrosion of rebar causes a severe problem that causes extensive damage to various types of structures. While considerable research has been carried out on measuring the amount of corrosion and methods to slow the progress of corrosion, a qualitative measurement technique that can measure the amount of corrosion of reinforcing steel need to be developed. The purpose of this research is to develop a new tech-nique to measure the corrosion level of rebar using accumulated thermal data. Accumulated thermal data were gathered using infrared cam-era and digitized to distinguish the difference between various corrosion levels of rebar. The test results shows that the higher level of corro-sion displays the higher level of temperature.
        4,000원
        19.
        2020.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This paper investigates the determinants of students’ success in Vietnam through conducting online interviews and surveys with 2,500 Vietnamese students at eight famous universities in Vietnam. By applying both SPSS 22 and STATA software, the study is to evaluate the impact of four driver factors, which affect GPA, language efficacy, and personal achievement. These factors are psychological perspective, home environmental, student demographic, and school environmental. The research results emphasize a positive effect of psychological and home-environmental determinants, but the negative effect of school environmental factors on the students’ success. Besides, the relationship between demographics and student success was tested and indicated that male students have a better language learning ability, but a low level of academic achievement than female students. The results also point out the impact of religious affiliation and ethnicity on personal achievement. Non-religious students are better achievers than those having a religion or those in minority ethnicity. Moreover, accumulated schooling years are negatively associated with students’ success. The more working experience students accrued, the higher possibility they are successful. Finally, the finding provides an insight into students’ success that might be useful to government authorities and other universities in designing policies for enhancing the quality of education.
        20.
        2020.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This study, not only investigates the important role of lifelong learning in shaping young people’s knowledge and in maximizing their potential, but also aims to shed light on the influencing factors of lifelong learning of young people in Vietnam. The author applied STATA and SPSS to analyze quantitative data collected from questionnaires with 332 respondents aged between 19 years old and 24 years old. Based on a holistic review of literature, this study concludes that four driver factors affect young people’s lifelong learning ability, comprising: organizational culture, motivation, human resource development, and domestic private type of enterprise. The results emphasize the positivity of organizational culture, human resource development, and the nature of work, especially organizational culture and human resource development, which are dominant reasons for young people to maintain lifelong learning. The relationship between demographics and lifelong learning was tested and it indicated that male has a stronger interest in learning than female. The result of the study also shows the impact of different types of business sectors on employees’ learning intentions. It points out that the domestic private type of enterprise is the most effective factor that has a positive relationship with the lifelong learning of the individual.
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