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        검색결과 16

        1.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To solve the problem of water pollution, researchers have proposed a photocatalytic degradation technology, in which the key factor is the development of efficient photocatalytic materials. Graphitic carbon nitride (g-C3N4), an n-type semiconductor, has been widely studied due to its suitable band gap (2.7 eV), low cost, easy preparation, non-toxicity, and high photostability. However, the pure-phase g-C3N4 still has defects such as low specific surface area, insufficient visible light absorption, low charge mobility, few active sites for interfacial reaction, and easy recombination of photogenerated electron–hole pairs, which leads to the lower photocatalytic activity of g-C3N4. Aiming at the problems mentioned above, this paper focus on the synthesis of g-C3N4-based composites with high photocatalytic activity via lemon juice induction method. Thiourea and lemon juice were selected as precursors, and carbon quantum dots (CQDs) as electron mediators were introduced anchoring on the surface of g-C3N4 to build g-C3N4/CQDs with compact interface. The results showed that small-sized CQDs are uniformly distributed on the surface of g-C3N4, and the g-C3N4/CQDs composite has a 2D0D structure, which reduces the recombination of photogenerated electron–hole pairs. The photocatalytic degradation efficiency of 4% g-C3N4/CQDs for RhB reaches the highest data of 90.9%, and the photocatalytic degradation rate is 0.016 min− 1, which is about 2.3 times that of g-C3N4. After four cycles of photocatalytic reaction, the photocatalytic degradation efficiency of the material remained at 81.7%. Therefore, the g-C3N4/CQDs synthesized via lemon juice induction has a more stable microstructure, and the charge separation efficiency is greatly improved, which is suitable for practical photocatalytic environmental protection.
        4,300원
        2.
        2019.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this paper we introduce a software package, the Very long baseline interferometry Network SIMulator (VNSIM), which provides an integrated platform assisting radio astronomers to design Very Long Baseline Interferometry (VLBI) experiments and evaluate the network performance, with a userfriendly interface. Though VNSIM is primarily motivated by the East Asia VLBI Network, it can also be used for other VLBI networks and generic interferometers. The software package not only integrates the functionality of plotting (u; v) coverage, scheduling the observation, and displaying the dirty and CLEAN images, but also adds new features including sensitivity calculations for a given VLBI network. VNSIM provides exible interactions on both command line and graphical user interface and o ers friendly support for log reports and database management. Multi-processing acceleration is also supported, enabling users to handle large survey data. To facilitate future developments and updates, all simulation functions are encapsulated in separate Python modules, allowing independent invoking and testing. In order to verify the performance of VNSIM, we performed simulations and compared the results with other simulation tools, showing good agreement.
        4,000원
        3.
        2019.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implement compatible optics systems. Simultaneous dual/multi-frequency VLBI observations at mm wavelengths with international baselines are thus possible. In this paper, we present the results from the first successful simultaneous 22/43 GHz dualfrequency observation with KaVA(KVN and VERA array), including images and astrometric results. Our analysis shows that the newly implemented simultaneous receiving system has brought a significant extension of the coherence time of the 43 GHz visibility phases along the international baselines. The astrometric results obtained with KaVA are consistent with those obtained with the independent analysis of the KVN data. Our results thus confirm the good performance of the simultaneous receiving systems for the non-KVN stations. Future simultaneous observations with more global stations bring even higher sensitivity and micro-arcsecond level astrometric measurements of the targets.
        4,000원
        4.
        2018.02 구독 인증기관 무료, 개인회원 유료
        Professor Petersmann has developed a constitutionalization theory for IEL based on Western constitutionalism theory in conjunction with human rights law. However, there is a paradox in his theory considering that he stresses ‘legal pluralism’ on the one hand, while calling for a cosmopolitan conception of IEL on the other hand. The hypothesis of this paper is that there are no ‘universalizable’ principles and common constitutional principles that can guarantee the compatibility between the two. Petersmann’s three often-used keywords, ‘human rights,’ “principles of justice,” and “judicial protection of individual rights,” are clarified in the context of Chinese thought and China’s progressive integration into the world economy. This paper finds that Petersmann’s theory focuses on bottom-up individual struggles, whereas Chinese thought is characterized by top-down overall consideration. The value divergence between the goodness of human nature in Chinese thought and the evil of human nature in Western thought makes ‘legal pluralism’ an insurmountable obstacle to a cosmopolitan conception of IEL.
        6,000원
        5.
        2016.10 구독 인증기관·개인회원 무료
        α-solanine is toxic to human health by disturbing digestive and central nervous systems. However, little information has been focused on investigated with respect to α-solanine influence in mammal oocyte maturation and quality. In this study, we investigated the effects of α-solanine on oocyte maturation, quality and possible molecular mechanisms in a pig model. Porcine Cumulus-oocyte complexes (COCs) were treated with increasing concentration (0, 1, 10, 20, 50 μM) of α-solanine subjected to further in vitro maturation culture. The result showed that α-solanine significantly inhibited cumulus cells expansion and increased oocyte death rates when the concentration of α-solanine more than 10 μM. After cell cycle and cytoskeleton analysis, the results showed that α-solanine (10 μM) disturbed meiotic resumption, increased abnormal spindle formation and cortical granules (CGs) distribution rates when compared with the untreated group. α-solanine (10 μM) triggered autophagy by increasing the expression of autophagy-related genes (LC3, ATG7, LAMP2) and accumulation of LC3-specific puncta (an autophagy maker). TUNEL staining assay showed that α-solanine significantly increased apoptosis in porcine oocytes confirmed by up-regulated the levels of BAX and CAPS3 genes. Further study revealed that exposure α-solanine (10 μM) to porcine oocytes induced ROS generation, reduced mitochondrial membrane potential. In addition, our results suggested that α-solanine (10 μM) significantly increased the levels of H3K36me3 and H3K27me3 in porcine oocytes. Taken together, these data indicated that α-solanine toxic impaired oocyte maturation and quality by inhibited cumulus cells expansion, increased abnormal spindle and CGs distribution rates, triggered autophagy/apoptosis occur, accumulated ROS, decreased mitochondrial membrane potential, and changed epigenetic modifications.
        7.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        VLBI experiments have been conducted by radio telescopes in the East Asia VLBI Network (EAVN) in which 14 telescopes in China, Japan, and Korea participated. One of the aims of the EAVN is to obtain higher angular resolution that is provided by the 6,000 km baseline between China and Japan and better sensitivity by adding large telescopes. Data were recorded at 1 a Gbps recording rate at all stations and processed on the Korea-Japan Joint VLBI Correlator (KJJVC) at the Korea-Japan Correlation Center (KJCC) after experiments. Fringes were obtained from these experiments conducted at 8 GHz and 22 GHz and post-correlation data analysis of the experiments is undergoing. The outcomes of these experiments open the possibility of conducting EAVN observations with global VLBI networks. In this presentation, the recent status of these experiments and future prospects are presented.
        3,000원
        8.
        2015.05 구독 인증기관 무료, 개인회원 유료
        Pigs are considered an ideal source of human disease model due to their physiological similarities to humans. However, the low efficiency of in vitro embryo production (IVP) is still a major barrier in the production of pig offspring with gene manipulation. Despite ongoing advances in the associated technologies, the developmental capacity of IVP pig embryos is still lower than that of their in vivo counterparts, as well as IVP embryos of other species (e.g., cattle and mice). The efficiency of IVP can be influenced by many factors that affect various critical steps in the process. The previous relevant reviews have focused on the in vitro maturation system, in vitro culture conditions, in vitro fertilization medium, issues with polyspermy, the utilized technologies, etc. In this review, we concentrate on factors that have not been fully detailed in prior reviews, such as the oocyte morphology, oocyte recovery methods, denuding procedures, first polar body morphology and embryo quality.
        4,000원
        11.
        2012.06 구독 인증기관·개인회원 무료
        The objective of the present study was to investigate the effects of different concentrations of sorbitol supplementation for in vitro maturation medium and in vitro culture medium, on porcine cumulus oocyte complexe(COC) maturation and subsequent developmental capacity after parthenogenetic activation. Porcine COC were cultured for 44 h(0~ 22 h termed MI stage and 22~44 h termed MII stage) in TCM199 without(— ) or with(+) sorbitol (20 μM, 100 μM, 200 μM), and the resultant metaphase II oocytes cultured in PZM-3 for 7 days following activation. Our results showed that supplementation with appropriate concentrations of sorbitol (20 μM) during full term maturation culture(MI+/MII+) significantly(p<0.05) improved blastocyst formation rates and total cell number. When the concentration of sorbitol were increased to 100 μM and 200 μM during maturation culture, the maturation rate of COC were significantly reduced compared with 20 μΜ or control groups. Also blastocyst formation rates significantly(p<0.05) reduced with increasing concentration of sorbitol(200 μM). Supplementation with sorbitol(20 μM, 50 μM, 100 μM) into PZM-3 for in vitro culture significantly(p<0.05) inhibited blastocyst formation compared with control group. However, the blastocyst formation rates start to rise again when 50 μ M sorbitol was used for the first 48 hours and then cultured in PZM-3 without sorbitol. There was no significant difference in cell number between control and sorbitol treated groups. When the activated oocytes were cultured in PZM-3 for 48h and then cultured in PZM-3 with sorbitol, interestingly, the blastocyst formation rate was similar to that of PZM-3 with sorbitol for in vitro culture and significantly lower than control group. These results suggest that addition of low concentrations of sorbitol(20 μM) during oocyte maturation is beneficial for subsequent blastocyst development and improved embryo quality. However, treatment with sorbitol supplementation during in vitro culture medium is negative effect to blastocyst formation.
        12.
        2016.04 서비스 종료(열람 제한)
        Four shear-deficient reinforced concrete (RC) beam specimens with different shear span ratios were tested using a well-instrumented drop-weight impact machine to gain a better understanding of the effect of shear span ratio on impact behavior of RC beams strengthened with carbon fibre reinforced polymer (CFRP). The results demonstrated that the shear span ratio could change the failure modes for strengthened specimens and also affect the impact resistance.
        13.
        2016.04 서비스 종료(열람 제한)
        This study is focused on three-dimensional nonlinear finite element analysis of reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymer (CFRP) strips under impact loading. The validity of the model was assessed through the comparison with experimental results obtained from drop-weight impact tests of the authors. The well agreement proves the feasibility of the proposed numerical analysis method.