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        검색결과 110

        1.
        2024.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Si-based anodes are promising alternatives to graphite owing to their high capacities. However, their practical application is hindered by severe volume expansion during cycling. Herein, we propose employing a carbon support to address this challenge and utilize Si-based anode materials for lithium-ion batteries (LIBs). Specifically, carbon supports with various pore structures were prepared through KOH and NaOH activation of the pitch. In addition, Si was deposited into the carbon support pores via SiH4 chemical vapor deposition (CVD), and to enhance the conductivity and mechanical stability, a carbon coating was applied via CH4 CVD. The electrochemical performance of the C/Si/C composites was assessed, providing insights into their capacity retention rates, cycling stability, rate capability, and lithium-ion diffusion coefficients. Notably, the macrostructure of the carbon support differed significantly depending on the activation agent used. More importantly, the macrostructure of the carbon support significantly affected the Si deposition behavior and enhanced the stability by mitigating the volume expansion of the Si particles. This study elucidated the crucial role of the macrostructure of carbon supports in optimizing Si-based anode materials for LIBs, providing valuable guidance for the design and development of high-performance energy-storage systems.
        4,300원
        2.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The thermocatalytic decomposition of methane is a promising method for hydrogen production. To determine the cause of carbonaceous catalyst deactivation and to produce high-value carbon, methane decomposition behavior and deactivated catalysts were analyzed. The surface properties and crystallinity of a commercial activated carbon material, MSP20, used as a methane decomposition catalyst, varied with the reaction time at a reaction temperature of 900 °C. During the initial reaction, MSP20 provided a methane conversion of ≥ 50%; however, the catalyst exhibited rapid deactivation as crystalline carbon grew at surface defects; after 15 min of reaction, approximately 33% methane conversion was maintained. With increasing reaction time, the specific surface area of the catalyst decreased, whereas crystallinity increased. The R-square value of the conversion–crystallinity relationship was significantly higher than that of the conversion–specific surface area relationship; however, neither profile was linear. The activity of the activated carbon catalyst for methane decomposition is mainly determined by the complex actions of the specific surface area and defect sites. The activity was maintained after an initial sharp decline caused by the continuous growth of crystalline carbon product. This study presents the application of carbonaceous catalysts for the decomposition reaction of methane to form COx- free hydrogen, while simultaneously yielding porous carbon materials with an improved electrical conductivity.
        4,200원
        4.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2021년 4월부터 8월에 제주시의 비닐하우스에서 재배되는 목이버섯에서 거저리 일종이 발견되었으며, 그를 동정한 결과 제주진주거저리 (Platydema takeii Nakane, 1956)로 확인되었다. 상업적으로 재배되는 버섯에 있어서 거저리 해충으로 인한 우리나라의 첫 번째 피해 사례이다. 여 기서는 이 해충의 피해 증상과 성충 및 유충의 진단형질을 제공하고자 한다.
        4,000원
        7.
        2021.03 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Celecoxib, a cyclooxygenase (COX)-2 selective inhibitor, was approved as a non-steroidal anti-inflammatory drug (NSAID), and this therapeutic application has been expanded to several other diseases, including colon cancer. Notably, a treatment strategy combining the use of celecoxib and radiation therapy has been employed for improving the control of local cancers. In this study, we examined the effect of celecoxib on irradiation-induced intestinal damage. The twenty four mice (BALB/c) were divided into four groups; 1) sham-irradiated control group, 2) celecoxib-treated group, 3) irradiated group, and 4) celecoxib-treated irradiation group. Mice were orally administered celecoxib at a dose of 25 mg/kg in a 0.1 mL volume, daily for 4 days after irradiation exposure (10 Gy). Then, histological examinations of the jejunal villous height, crypt survival, and crypt size were performed. The expression of COX-2 after administration of celecoxib in irradiated mice was examined by employing immunohistochemistry, Western blotting, and qPCR analysis. The jejunal villi height and the crypt survival were reduced in the irradiation group compared with the sham-irradiated group. Celecoxib treatment in irradiation mice even more decreased those indicators. Crypt size was increased in the radiation group compared to the sham-irradiated control group, whereas the size was decreased in the celecoxibtreated irradiation group compared with the group exposed to the radiation injury. COX-2 expression was detected in the crypt of the small intestine, and COX-2 expression was increased in the crypt lesion following radiation exposure. However, COX-2 expression was reduced in the celecoxib-treated irradiation group. Therefore, in the present study, we confirmed that celecoxib treatment after irradiation aggravated the irradiation-induced intestinal damage. These results suggest that a caution need to be administered when celecoxib treatment is performed in combination with radiation therapy for cancer treatment.
        4,000원
        10.
        2019.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        During the winter of 2017/2018, significantly low water temperatures were detected around the western and southern coasts of Korea (WSCK). In this period, sea surface temperature (SST) in the Korea Waters was about 2℃ lower than mean temperature. Using the real-time observation system, we analyzed the temporal variation of SST during this period around the western and southern coasts. Low water temperature usually manifested over a period of about 10 ~ 20 days. The daily Arctic oscillation index was also similarly detectable with the variation of SST. From the cross-correlation function, we compared two periodic variations, which were SST around the WSCK and the Arctic oscillation index. The cross correlation coefficients between both variations were approximately 0.3 ~ 0.4. The time lag of the two time series was about 6 to 7 days. Therefore, significanlyt low water temperatures during winter in the Korean coastal areas usually became detectable 6 to 7 days after the negative peak of Arctic oscillation.
        4,000원
        11.
        2019.04 구독 인증기관·개인회원 무료
        This study was carried out to confirm the predatory and developmental features of N. stenoferus. We determine the host range of N. stenoferus. As a result, it was confirmed that Aphis gssypii, Myzus persicae, Planococcus citri, and Frankliniella occidentalis. N. stenoferus is thought to be able to feed on other micro pests. The test for a developmental period of N. stenoferus at 25℃ showed that the egg period was about 10 days. The nymphal period was about 18 days. Each nymphal period from 1st instar to 3rd instar nymphs was about 3 days. And the nymphal period of 4th and 5th were about 3.5 and 6 days, respectively. The female adult laid eggs in stem tissue or on leaves, and sometimes on the soaked cotton for water supply.
        12.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The osmolarity of a medium that is commonly used for in vitro culture (IVC) of oocytes and embryos is lower than that of oviductal fluid in pigs. In vivo oocytes and embryos can resist high osmolarities to some extent due to the presence of organic osmolytes such as glycine and alanine. These amino acids act as a protective shield to maintain the shape and viability in high osmotic environments. The aim of this study was to determine the effects of glycine or/and alanine in medium with two different osmolarities (280 and 320 mOsm) during IVC on embryonic development after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) in pigs. To this end, IVC was divided into two stages; the 0-2 and 3-7 days of IVC. In each stage, embryos were cultured in medium with 280, 320, or 360 mOsm and their combinations with or without glycine or/and alanine according to the experimental design. Treatment groups were termed as, for example, "T(osmolarity of a medium used in 0-2 days of IVC)-(osmolarity of a medium used in 3-7 days of IVC)" T280-280 was served as control. When PA embryos were cultured in medium with various osmolarities, T320-280 showed a significantly higher blastocyst formation (29.0%) than control (22.2%) and T360-360 groups (6.9%). Glycine treatment in T320-280 significantly increased blastocyst formation (50.4%) compared to T320-280 only (36.5%) while no synergistic was observed after treatment with glycine and alanine together in T320-280 (45.7%). In contrast to PA embryonic development, the stimulating effect by the culture in T320-280 was not observed in SCNT blastocyst development (27.6% and 23.7% in T280-280 and T320-280, respectively) whereas the number of inner cell mass cells was significantly increased in T320-280 (6.1 cells vs. 9.6 cells). Glycine treatment significantly improved blastocyst formation of SCNT embryos in both T280-280 (27.6% vs. 38.0%) and T320-280 (23.7% vs. 35.3%). Our results demonstrate that IVC in T320-280 and treatment with glycine improves blastocyst formation of PA and SCNT embryos in pigs.
        4,000원
        15.
        2018.10 구독 인증기관·개인회원 무료
        This study was carried out to confirm the parasitic and developmental features of A. japonica and D. suzkii was used as a parasitic natural enemy. A. japonica attacked the D. suzukii larvae and the emergence of adults were observed from D. suzukii pupae. Black spots were observed in parasitized D. suzukii larvae. Mortality of parasitized larvae, rate of parasitic and developmental feature were investigated according to developmental stages of host, D. suzukii. Mortality and rate of parasitic of D. suzukii larvae were the highest when second instar larvae were attacked. Developmental period of parasitized D. suzukii larvae showed differences to developmental stages, but there was no significant difference in developmental stage of pupal period.
        16.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적 : 본 연구는 중심부 암점을 가진 환자에게 한글 기반의 중심외보기 훈련 소프트웨어를 적용하여 그 효과성을 파악하고자 하였다. 연구방법 : ABA 단일대상연구(single-subject research design) 설계를 위해 중심부 암점을 가진 2명의 환자에게 훈련 전후 기초선 각 3회기, 중심외보기 훈련은 8회기를 시행하였다. 매회기 훈련 종료 후에 단문읽기속도를 측정하였고, 훈련전과 훈련 후에 일기활동 능력을 평가하기 위하여 캐나다작업수행측정(Canadian Occupational Performance Measure; COPM)와 운동처리기술평가(Assessment of Motor and Process Skills; AMPS)를 시행하였다. 결과 : 중심외보기 훈련 결과 대상자 모두의 읽기속도가 훈련 전보다 훈련 후에 2표준편차 이상 증가하였고, 특히 훈련 2-3회기에 큰 증가세를 나타냈다. 전반적인 일상생활활동 능력에서는 훈련 전후 변화가 없었으나, 읽기와 관련된 활동에서는 의미있는 향상을 나타냈다. 결론 : 본 연구를 통하여 한글기반의 중심외보기 훈련 프로그램이 중심부 암점을 갖고 있는 환자의 읽기활동 수행 수준을 향상시킬 수 있음을 확인하였고, 국내 임상현장에서 적용할 근거를 마련하였다.
        4,200원
        17.
        2018.07 구독 인증기관·개인회원 무료
        From the first inspiration of a desire until a product reaches hands, consumers go through complex and multi-faceted interactions with brands, involving myriads of channels and media. As such, it is important for marketers to understand this shopping “journey” since it is where brands can influence and persuade consumers most effectively and efficiently. In this study, we conduct an exploratory study to understand the patterns and correlates of pre-purchase behaviors and the relationship to actual purchases (made both online and offline) by analyzing survey data obtained in Korea and China. In particular, we examine three key drivers for pre-purchase behaviors: product category, market maturity, and consumer tendencies. To address category-level differences, we compare and contrast grocery and electronics. As for the market maturity, we study Korea and China in which e-commerce is at different stages of development. Finally, consumer tendencies are measured by general shopping tendencies, online activity patterns, and risk perception for e-commerce. Our empirical analyses provide the following findings. First, general shopping tendencies impact the pre-purchase behavior in grocery buying, but not electronics, for both Korea and China. Second, online activity patterns (entertainment and content-creating activities) have an impact on the shopping journey in both categories. Third, risk perceptions for ecommerce only affect pre-purchase behaviors of Chinese consumers. That is, in a developing market at an earlier stage of e-commerce development, consumers perceive online transactions more risky and uncertain, leading to greater pre-purchase behaviors. Lastly, we investigate the link from the information search to the final purchase stages. Consumers buying grocery present a positive and significant relationship between prepurchase and final purchase behaviors whereas electronics present no such relationship across the stages of the consumer shopping journey.
        18.
        2018.05 구독 인증기관·개인회원 무료
        In case of performing asphalt pavement overlay on existing concrete pavement layer, applying asphalt emulsion tack-coating or spreading prime-coating is considered to improve adhesion between asphalt and concrete layer. After coating work is done a curing process is considered not only for promoting evaporation process in coated (and/or spread) asphalt emulsion, but also for generating a membrane which can act as a bonding agent. Finally, asphalt overlay construction is performed when this curing process is completely done. However, during asphalt overlay construction process remarkable amount of spread tack-coating layer is lost due to asphalt material transfer vehicles (e.g. trucks, approximately 40~50% of total spread tack coating material is lost). In this paper, a new pavement equipment contains simultaneous asphalt emulsion spreading ability and corresponding construction techniques are introduced. Through applying this equipment, non-stop two step sequent working process: spreading asphalt emulsion on to existing concrete pavement layer then paving asphalt material for overlay construction, is available. During pavement working process temperature of asphalt material was kept with ranged between 130ºC and 170ºC. After performing field performance evaluation, it was found that crucial improvement in pavement layer adhesion, crack and rutting resistant ability were observed compared to the conventional paving method.
        19.
        2017.10 구독 인증기관·개인회원 무료
        In recent 10 years, mushroom cultivation area and number of cultivators have decreased, but mushroom production tends to increase. This shows that mushroom cultivation is being transformed from log and bed cultivation to bottle cultivation using automated facilities with high productivity per unit area. The bottle cultivation is possible to mechanized and automated, which can save manpower, less damage to pests, can be cultivated throughout the year, and is uniform in quality and advantageous for mass production. However, the investment in production facilities and farm materials is very large compared to the production of logs and bed cultivars, which can lead to large losses in the case of failure to grow. Therefore, it is necessary for the farmers who want to start the bottle cultivation to make careful management decisions by carefully examining the investment cost, the operating cost, and the expected income that are put into the bottle cultivation system. This study was conducted to analyze the management performance of bottle cultivation in mushroom farm and use it as farming decision making data. As a result of analysis of the management performance through farmers' survey, it was found that such as cost of spawn, substrate materials, other material, employment effort, and fuels & electricity power cost accounted for a large proportion of the cost of bottle cultivation.
        20.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, p-type Bi−Sb−Te alloys powders are prepared using gas atomization, a mass production powder preparation method involving rapid solidification. To study the effect of the sintering temperature on the microstructure and thermoelectric properties, gas-atomized powders are consolidated at different temperatures (623, 703, and 743 K) using spark plasma sintering. The crystal structures of the gas-atomized powders and sintered bulks are identified using an X-ray diffraction technique. Texture analysis by electron backscatter diffraction reveals that the grains are randomly oriented in the entire matrix, and no preferred orientation in any unique direction is observed. The hardness values decrease with increasing sintering temperature owing to a decrease in grain size. The conductivity increases gradually with increasing sintering temperature, whereas the Seebeck coefficient decreases owing to increases in the carrier mobility with grain size. The lowest thermal conductivity is obtained for the bulk sintered at a low temperature (603 K), mainly because of its fine-grained microstructure. A peak ZT of 1.06 is achieved for the sample sintered at 703 K owing to its moderate electrical conductivity and sustainable thermal conductivity.
        4,000원
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