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        검색결과 371

        1.
        2024.04 구독 인증기관·개인회원 무료
        Hand, foot, and mouth disease (HFMD) is a highly contagious disease with no specific treatment. Since it is common in immunocompromised children under the age of 5, there is a need to develop a safe vaccine. Virus-like particles (VLPs) are similar structures to viruses with the lack of genetic material which makes them impossible to replicate and infect, and therefore have a high level of biological safety and are considered to have high value as vaccines. In this study, the insect virus expression system that is widely used for vaccine and drug production due to its high post-translational modification efficiency, was used to produce VLPs for Coxsackievirus type A6 and A10, which are recently reported to be the main causes of HFMD. For this purpose, the selection of promoters that can control the timing and intensity of expression of 3CD protein, which is essential for VLPs assembly but has been reported to be cytotoxic, was conducted to construct an optimal expression form for HFMD-VLP.
        2.
        2024.04 구독 인증기관·개인회원 무료
        Distractive marking, as conceptualized by Abbott H. Thayer, refers to diminutive patterns of contrasting colors on an animal’s body. Thayer hypothesized that these patterns augment camouflage by diverting predatory focus from the outline of the prey, however, the evidence was insufficient. In this study, we verified the hypothesis that the presence of distractive markings confers a survival advantage under specific conditions. Specifically, the experiment aimed to ascertain whether the existence of lichens on trees hinders the visual detection of prey, given that lichens resemble distractive markings. The experimental design involved human subjects as predators and artificial moth images on a monitor as prey. The survival of moths with and without distractive markings was compared, also considering the influence of the presence of lichens in the background. As an analysis result, the survival likelihood of moths was statistically significantly hindered when the distractive marking was present. This result contradicts Thayer‘s hypothesis and implies the presence of a function distinct other than the enhancement of camouflage.
        3.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        실제세계에서 데이터 수집의 비용과 한계를 고려할 때, 시뮬레이션 생성 환경은 데이터 생성 과 다양한 시도에 있어 효율적인 대안이다. 이 연구에서는 Unity ML Agent를 로그라이크 장 르에 적합한 강화학습 모델로 구현하였다. 간단한 게임에Agent를 이식하고, 이 Agent가 적을 인식하고 대응하는 과정을 코드로 작성하였다. 초기 모델은 조준사격의 한계를 보였으나 RayPerceptionSensor-Component2D를 통해 Agent의 센서 정보를 직접 제공함으로써, Agent가 적을 감지하고 조준 사격을 하는 능력을 관찰할 수 있었다. 결과적으로, 개선된 모델 은 평균3.81배 향상된 성능을 보여주었으며, 이는 Unity ML Agent가 로그라이크 장르에서 강화학습을 통한 데이터 수집이 가능함을 입증한다.
        4,000원
        4.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Liquid phase exfoliation of natural graphite is an industrially effective solution for graphene preparation. However, many countries have identified natural graphite as a strategic resource and restricted its mining. In this report, we used abundant and readily available needle coke (NC) as a graphene exfoliation precursor and sodium carboxymethyl cellulose (CMC) as a dispersant to prepare a sandwich structured conductive graphitized NC nanosheets (GNCNs) by liquid phase exfoliation, freeze-drying and high-temperature graphitization, in which a graphene layer is sandwiched between two thin CMC layers. CMC could increase the liquid absorption and retention ability of the conductive agent and improve the migration rate of lithium ions. The highly ordered graphene layer could accelerate the transmission of electrons. The GNCNs with 0.4 wt% CMC addition showed good rate performance (144.6 mAh g− 1 at 5 C) and high cycle stability (96.2% after 200 cycles at 1 C) for LiFePO4 (LFP) battery. The traditional Super-P (SP) conductive agent exhibited low-rate performance (113.9 mAh g− 1 at 5 C) and cycle performance (89.9% after 200 cycles at 1 C). This study offers a novel approach to selecting graphene precursors and has promising applications for conductive additives in high-performance LFP batteries.
        4,800원
        5.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Organic wastewater causes serious environmental pollution, and catalytic oxidation is promising technique for wastewater treatment. Developing green and effective catalysts is currently challenging. In this work, green synthesis of nano zerovalent iron loaded onto porous biochar derived from popcorn is conducted, and catalytic oxidation of Rhodamine B (RhB) is evaluated in the presence of H2O2. Effect of process factors is examined on catalytic performance for RhB removal. The mechanism of RhB removal is discussed by characterizations (Fourier transform infrared spectra and Raman) and UV–vis spectra. RhB removal is improved with high catalyst dosage, low initial RhB concentration, and high reaction temperature, while it is slightly influenced by carbonization temperature of biochar, H2O2 dosage and pH value. Under conditions of BC-250 1.0 g/L, H2O2 0.01 mol/L, pH 6.1, and temperature 30 °C, the removal rate of RhB is 92.27% at 50 min. Pseudo first-order kinetics is used to fitting experimental data, and the activation energy for RhB removal in BC-250/H2O2 system is 39 kJ/mol. RhB removal in BC-250/H2O2 system can be attributed to adsorption effect and catalytic oxidation with the dominant role of hydroxyl radical. This work gives insights into catalytic oxidation of organic wastewater using green catalyst.
        4,200원
        6.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Intervertebral disc disease is a medical condition in which the disc, a fibrocartilage substance, escapes in the spinal cavity and compresses the spinal cord and it often co-occurs with Chiari-like malformation. A 7-year-old Pomeranian dog was referred for a forelimb ataxia. Disc protrusion at C2 to C3, crowding of the caudal fossa and mild cerebellar herniation into the foramen magnum were confirmed through Computed tomography and magnetic resonance imaging. The patient was hospitalized for two weeks and received electroacupuncture along with other rehabilitation therapies. After 2 weeks of inpatient treatment, there was an improvement in the patient's clinical symptoms.
        3,000원
        7.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Salivary gland dysfunction is a common complication of diabetes. Decreased saliva production and changes in saliva composition may cause oral diseases. Reactive oxygen species (ROS) generation in the salivary glands results in the loss of acinar cells and decreased saliva secretion. Glucagon-like peptide 1 (GLP-1) is the incretin hormone that regulates blood glucose level and can suppress ROS production and inflammation through its antioxidant effects. Dipeptidyl peptidase-4 (DPP-4) is an enzyme that breaks down GLP-1. In this study, we evaluated the pathological role of DPP-4 and GLP-1 on salivary gland dysfunction in type 2 diabetic db/db mice. We observed reduced salivary secretion and histopathological alteration of salivary glands in the db/db mice. The increased DPP-4 and decreased GLP-1 levels in the salivary glands were also detected in the db/db mice. Furthermore, the db/db mice had increased apoptosis and oxidative injury in salivary glands. There was an accumulation of advanced glycation end products and mucus in the salivary glands of the db/db mice. In conclusion, these results showed the possible involvement of DPP-4 and GLP-1, leading to increased ROS-induced apoptosis in diabetes-related salivary gland dysfunction. DPP-4 and GLP-1 may be a pharmacological target for patients with diabetes-related salivary gland dysfunction.
        4,300원
        8.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기존의 스타크래프트II 내장AI는 미리 정의한 행동 패턴을 따르기 때문에 사용자가 전략을 쉽게 파악할 수 있어 사용자의 흥미를 오랫동안 유지시키기 힘들다. 이를 해결하기 위해, 많은 강화학습 기반의 스타크래프 트II AI 연구가 진행되었다. 그러나 기존의 강화학습AI는 승률에만 중점을 두고 에이전트를 학습시킴으로써 소수의 유닛을 사용하거나 정형화 된 전략만을 사용하여 여전히 사용자들이 게임의 재미를 느끼기에 한계가 존재한다. 본 논문에서는 게임의 재미를 향상시키기 위하여, 강화학습을 활용하여 실제 플레이어와 유사한 AI을 제안한다. 에이전트에게 스타크래프트II의 상성표를 학습시키고, 정찰한 정보로 보상을 부여해 유동적 으로 전략을 변경하도록 한다. 실험 결과, 사용자가 느끼는 재미와 난이도, 유사도 부분에서 고정된 전략을 사용하는 에이전트보다 본 논문에서 제안하는 에이전트가 더 높은 평가를 받았다..
        4,000원
        9.
        2023.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        파골세포양 거대세포형 미분화 암종은 췌장암의 1%만을 차지하는 흔치 않은 암종으로 알려져 있다. 저자들은 39세 남자에게서 진단된, 수술 및 항암치료를 시행한 1예를 소개하고자 한다.
        4,000원
        11.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phytohormones (plant hormones) are a class of small-molecule organic compounds synthesized de novo in plants. Although phytohormones are present in trace amounts, they play a key role in regulating plant growth and development, and in response to external stresses. Therefore, the analysis and monitoring of phytohormones have become an important research topic in precision agriculture. Among the various detection methods, electrochemical analysis is favored because of its simplicity, rapidity, high sensitivity, and in-situ monitoring. Graphene and graphene-like carbon materials have abundant sources, exhibiting large specific surface area, and excellent physicochemical properties. Thus, they have been widely used in the preparation of electrochemical biosensors for phytohormone detection. In this paper, the research advances of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection have been reviewed. The properties of graphene and graphene-like carbon materials are first introduced. Then, the research advances of electrochemical biosensors (including conventional electrochemical sensors, photoelectrochemical sensors, and electrochemiluminescence sensors) based on graphene and graphene-like carbon materials for phytohormone detection is summarized, with emphasis on their sensing strategies and the roles of graphene and graphene-like carbon materials in them. Finally, the development of electrochemical sensors based on graphene and graphene-like carbon materials for phytohormone detection is prospected.
        4,900원
        12.
        2023.07 구독 인증기관·개인회원 무료
        This paper tests firms’ strategic response to negative consumer sentiment. We use sentiment analysis on social media posts to detect and proxy for negative consumer sentiments toward the firms and operationalize the number of ESG positive news about the firms as the strategic response to the sentiment. We document a surprising phenomenon that negative sentiment toward a firm is positively associated with future ESG news announcements by the firm. The effect is stronger for B2B firms than for B2C ones. We argue this is the firm’s strategic reaction rather than being a true change in the firm’s ESG policy, because (1) The ESG effect only lasts for a short period, and (2) the negative sentiment toward the firm decreases after the ESG news. Using former US president Trump’s tweets as external shocks, we show the causal relationship in a DID framework.
        13.
        2023.07 구독 인증기관·개인회원 무료
        Social media has emerged as a prevalent tool for businesses in recent years through which brands actively engage in promotions. This development has resulted in several social media trends aimed at garnering increased consumer engagement on various social media platforms that brands utilize routinely. We investigate one such prevalent social media trend: brands sharing memes. Several popular brands, such as Netflix, regularly post memes on social media platforms. Therefore, it is important to study the brands’ use of memes and their resultant impact on consumer behavior.
        14.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Germ cells undergo towards male or female pathways to produce spermatozoa or oocyte respectively which is essential for sexual reproduction. Mesenchymal stem cells (MSCs) have the potential of trans-differentiation to the multiple cell lineages. Methods: Herein, rat MSCs were isolated from bone marrow and characterized by their morphological features, expression of MSC surface markers, and in vitro differentiation capability. Results: Thereafter, we induced these cells only by retinoic acid supplementation in MSC medium and, could able to show that bone marrow derived MSCs are capable to trans-differentiate into male germ cell-like cells in vitro. We characterized these cells by morphological changes, the expressions of germ cell specific markers by immunophenotyping and molecular biology tools. Further, we quantified these differentiated cells. Conclusions: This study suggests that only Retinoic acid in culture medium could induce bone marrow MSCs to differentiate germ cell-like cells in vitro . This basic method of germ cell generation might be helpful in the prospective applications of this technology.
        4,000원
        15.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Toll-like receptor 4 (TLR4) is known to contribute to the modulation of insulin resistance and systemic inflammation seen in obesity and the metabolic syndrome. The present study was performed to investigate the fertility competence of TLR4 knock out male mice (TLR4 mice) on a high-fat diet (HFD), compared to a normal-chow diet (NCD). The controls included wildtype (WT) mice fed on a HFD or NCD. Six-week-old male mice were fed with either a NCD or HFD for 20 weeks. Body and organ weights, serum levels of glucose, triglycerides and hepatoxicity, sperm quality and spermatogenesis were observed after the sacrifice. Also, randomly selected male mice were mated with virgin female mice after feeding of 19 weeks. The weight of the body and organs increased in WT and TLR4 mice on a HFD compared to those of mice on a NCD. The weights of the reproductive organs did not vary among the treatment groups. The motility and concentration of the epididymal spermatozoa decreased in both WT and TLR4 mice fed a HFD. The pregnancy rate and litter size declined in the HFD-fed WT mice compared to the HFD-fed TLR4 mice. In conclusion, the HFD alters energy and steroid metabolism in mice, which may lead to male reproductive disorders. However, fertility competence was somewhat restored in HFD-fed TLR4 male mice, suggesting that the TLR4 is involved in testis dysfunction due to metabolic imbalance.
        4,300원
        16.
        2023.05 구독 인증기관·개인회원 무료
        The acoustic emission (AE) method as a passive non-destructive monitoring technique is proposed for real-time monitoring of mechanical degradation in underground structures, such as deep geological disposal of high-level nuclear waste (HLW). This study investigates the low-frequency characteristics of AE signals emitted during the fracturing of meter-scale concrete specimens; uniaxial compression tests (UCT) in a lab scale and Goodman jack (GJ) tests in a 1.3 m-long concrete block were conducted while acquiring the AE signals using low-frequency AE sensors. The results indicate a sharp increase in AE energy emission at approximately 60% and 80% of the yield stresses in the UCT and GJ tests, respectively. The collected AE signals were primarily found in two frequency bands: the 4-28 kHz range and the 56-80 kHz range. High-frequency AE signals were captured more as the stress increased in the GJ tests, which was in contrast to the UCT tests. Furthermore, the AE signals obtained from the Goodman jack tests tended to lower RA values than the UCT results. This study presents unique experimental data with low-frequency AE sensors under different loading conditions, which provides insights into field-scale AE monitoring practices.
        17.
        2023.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study assessed the influences of fluorine introduced into DLC films on the structural and mechanical properties of the sample. In addition, the effects of the fluorine incorporation on the compressive stress in DLC films were investigated. For this purpose, fluorinated diamond-like carbon (F-DLC) films were deposited on cobalt-chromium-molybdenum substrates using radio-frequency plasma-enhanced chemical vapor. The coatings were examined by Raman scattering (RS), Attenuated total reflectance Fourier transform infrared spectroscopic analysis (ATR-FTIR), and a combination of elastic recoil detection analysis and Rutherford backscattering (ERDA-RBS). Nano-indentation tests were performed to measure hardness. Also, the residual stress of the films was calculated by the Stony equation. The ATR-FTIR analysis revealed that F was present in the amorphous matrix mainly as C-F and C-F2 groups. Based on Raman spectroscopy results, it was determined that F made the DLC films more graphitic. Additionally, it was shown that adding F into the DLC coating resulted in weaker mechanical properties and the F-DLC coating exhibited lower stress than DLC films. These effects were attributed to the replacement of strong C = C by feebler C-F bonds in the F-DLC films. F-doping decreased the hardness of the DLC from 11.5 to 8.8 GPa. In addition, with F addition, the compressive stress of the DLC sample decreased from 1 to 0.7 GPa.
        4,000원
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