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        검색결과 45

        3.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To investigate the effect of the catalyst and metal–support interaction on the methane decomposition behavior and physical properties of the produced carbon, catalytic decomposition of methane (CDM) was studied using Ni/SiO2 catalysts with different metal–support interactions (synthesized based on the presence or absence of urea). During catalyst synthesis, the addition of urea led to uniform and stable precipitation of the Ni metal precursor on the SiO2 support to produce Ni-phyllosilicates that enhanced the metal–support interaction. The resulting catalyst upon reduction showed the formation of uniform Ni0 particles (< 10 nm) that were smaller than those of a catalyst prepared using a conventional impregnation method (~ 80 nm). The growth mechanisms of methane-decomposition-derived carbon nanotubes was base growth or tip growth according to the metal–support interaction of the catalysts synthesized with and without urea, respectively. As a result, the catalyst with Ni-phyllosilicates resulting from the addition of urea induced highly dispersed and strongly interacting Ni0 active sites and produced carbon nanotubes with a small and uniform diameter via the base-growth mechanism. Considering the results, such a Ni-phyllosilicate-based catalyst are expected to be suitable for industrial base grown carbon nanotube production and application since as-synthesized carbon nanotubes can be easily harvested and the catalyst can be regenerated without being consumed during carbon nanotube extraction process.
        4,300원
        4.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250oC.
        4,000원
        6.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Consumers want to express their original unique personality, and even are willing to endure high expenses in order to do this. One noticeable strategy in the market, used by companies to suit for this consumer sentiment, is that of employing limited edition marketing and limited free gifts. This study investigated the effects of limited free gifts on consumer response. Specifically, the present study examined how the need for uniqueness moderated the effects of limited free gifts on brand commitment and attitudes. The online survey method was used to gather the data and a total of 224 data were used to analyze data. The results of the research were as follows. The findings revealed four dimensions of limited free gifts: scarcity/specialty, not for sale, complementarity, and risk. Complementarity positively affected brand commitment, while all four dimensions of limited free gifts positively influenced brand attitude. In addition, the need for uniqueness was proven to be the strongest variable which positively influenced brand commitment and attitudes. Also, when the need for uniqueness was applied as a moderating variable, depending on the levels of the need for uniqueness, the effects of riskiness on the consumer’s response were shown to be different. The findings of this study infer various academic and practical applications.
        5,500원
        7.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fibrous adsorbents, such as activated carbon fibers (ACF) have acknowledged advantages of rapid adsorption rate and ease of modification compared with granular and powdered adsorbents. Based on the surface modification of lyocell-based ACF, we observed different surface characteristics of ACF samples with variation in the mixing ratio and impregnation time of H3PO4, NaCl, and KMnO4 solution. For an engineering application, we also explored the adsorption characteristics of thusproduced ACF samples onto volatile organic compounds (VOCs). Isothermal adsorption experiments were performed using toluene and benzene as adsorbates. Results indicate that both physical and chemical surface properties have an effect on the adsorption of volatile organic compounds (VOCs).
        4,000원
        10.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the retail environment where online-shopping malls are growing, offline store are find it difficult to survive simply by selling their products. As a result, offline retailers are trying to find unique services that are appealing to their customers. In such a market environment, marketing strategies that stimulate the five senses other than the sight can be an alternative. Therefore, this research is aimed at observing the effect of the senses on emotion and purchase intention in a fashion retail context. A two by two experimental design (existence vs non-existence of scent x existence vs. nonexistence of eating chocolate) between subjects was used. A total of 120 participants were randomly assigned to the four situations, and they were asked to complete the questionnaires about emotion and purchase intention. The survey data were statistically analyzed using SPSS 23.0, and results are as follows. After a two-way ANOVA, we observed a statistically significant effect of the scent service on pleasure and purchase intention the sweet offering service on purchase intention. Moreover, when scents service and sweet offering service were provided at the same time, the highest purchase intention was obtained among other services. In addition, we studied the effects of emotions on purchase intentions, and the pleasant emotions resulting from the services have a positive effect of on purchase intentions.
        4,500원
        11.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Coke aggregates and carbon artifacts were produced to investigate the interactions of coke and pitch during the kneading process. In addition, the kneading ratio of the coke and binder pitch for the coke aggregates was controlled to identify the formation of voids and pores during carbonization at 900°C. Experiments and thermogravimetric analysis revealed that carbon yields were improved over the theoretical yield calculated by the weight loss of the coke and binder pitch; the improvement was due to the binding interactions between the coke particles and binder pitch by the kneading process. The true, apparent, and bulk densities fluctuated according to the kneading ratio. This study confirmed that an excessive or insufficient kneading ratio decreases the density with degradation of the packing characteristics. The porosity analysis indicated that formation of voids and pores by the binder pitch increased the porosity after carbonization. Image analysis confirmed that the kneading ratio affected the formation of the coke domains and the voids and pores, which revealed the relations among the carbon yields, density, and porosity.
        4,000원
        12.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : Thermal cracking (also called low-temperature cracking) is a serious stress for asphalt pavement, especially in eastern South Korea, the northern USA, and Canada. Thermal cracking occurs when the level of thermal stress exceeds the corresponding level of low temperature strength of the given asphalt materials. Therefore, computation of thermal stress is a key factor for understanding, quantifying, and evaluating the level of low-temperature cracking resistance of asphalt pavement. In this paper, two different approaches for computing thermal stress on asphalt binder were introduced: Hopkins and Hamming’s algorithm (1967) and the application of a simple power-law function. All the computed results were compared visually; then the findings and recommendations were discussed. METHODS: Thermal stress of the tested asphalt binder was computed based on the methodology introduced in previous literatures related to viscoelastic theory. To perform the numerical analysis, MATLABTM 2D matrix-correlation and Microsoft Excel visual basic code were developed and used for the function fitting and value-minimization processes, respectively. RESULTS : Different results from thermal stress were observed with application of different computation approaches. This variation of the data trends could be recognized not only visually but also statistically. CONCLUSIONS: It can be concluded that these two different computation approaches can successfully provide upper and lower limits (i.e. boundaries) for thermal stress prediction of a given asphalt binder. Based on these findings, more reliable and reasonable thermal stress results could be provided and finally, better pavement performance predictions could also be expected.
        4,000원
        13.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study conducted to predict the stock market prices based on the assumption that internet news articles might have an impact and effect on the rise and fall of stock market prices. The internet news articles were tested to evaluate the accuracy by comparing predicted values of the actual stock index and the forecasting models of the companies. This paper collected stock news from the internet, and analyzed and identified the relationship with the stock price index. Since the internet news contents consist mainly of unstructured texts, this study used text mining technique and multiple regression analysis technique to analyze news articles. A company H as a representative automobile manufacturing company was selected, and prediction models for the stock price index of company H was presented. Thus two prediction models for forecasting the upturn and decline of H stock index is derived and presented. Among the two prediction models, the error value of the prediction model ① is low, and so the prediction performance of the model ① is relatively better than that of the prediction model ②. As the further research, if the contents of this study are supplemented by real artificial intelligent investment decision system and applied to real investment, more practical research results will be able to be developed.
        4,000원
        14.
        2018.05 구독 인증기관·개인회원 무료
        The ride quality (i.e. smoothness) is a key factor for evaluating the construction quality of expressway asphalt pavement. Conventionally, three paving devices are widely used to control the surface layer thickness: leveling sensor (i.e. LS), short-range-surfacing-contact-ski (i.e. SSCS) and long-range-surfacing-contact-ski (i.e. LSCS). However, each of these levelling tools presents one major drawback. In the case of LS, if the original sub-layer evenness is poor, the final asphalt pavement surface and its smoothness will be negatively affected. The SSCS cannot assure satisfactory smoothness when relatively long paving section (in the order of 10 km) are paved. While the LSCS would reduce the drawback of the SSCS, its weight on the one hand and its length on the other discourage its use in the paving site especially for curved sections. In this paper, a next generation pavement smoothness leveling equipment, known as non-contact-digital-ski (i.e. NCDS) was implemented, evaluated and compared to the conventional equipment leveling device. The international Roughness Index (IRI m/km) was measured on sections paved with and without NCDS and the results visually and statistically compared. In addition, for the same sections, the modulus of the pavement layers was computed and compared by means of Falling Weight Deflectometer (i.e. FWD). It was observed that when NCDS is used for asphalt pavement overlay of existing concrete pavement, significant improvement in IRI (i.e. IRI<1.0m/km) and consistently uniform elastic modulus could be achieved compared to the conventional levelling and paving method.
        15.
        2018.04 구독 인증기관·개인회원 무료
        The fruit house fly Atherigona orientalis (Schiner), which is belonging to Muscidae, Diptera, is classified as quarantine pest and first reported in Korea at 2016. Annual occurrence and spatial distribution pattern of A. orientalis was biweekly monitored from April to December, using fly-wine trap in Korea. A. orientalis was first found in Gwangyang in June and increased populations by September, 2017. It is considering that A. orientalis is difficult to survive during winter season because this species is belonging to non-diapausing insect, so it may possible to be overwintering in warm place such as green house of paprika and tomato during winter. Based on this survey, A. orientalis is considered to be excluded from quarantine pests.
        16.
        2018.04 구독 인증기관·개인회원 무료
        Plant quarantine is preventing the introduction and adaption of exotic pests in homeland, and then eventually promoting and improving domestic agriculture and forestry. Therefore, we conducted a survey of intercepted pests on hand-carried plants from all over the world to Korea. Totally 7,291 of hand-carried plants had been inspected by quarantine inspectors at 2017. Gimpo, Daegu, and Incheon International Airport showed more inspection cases than other areas by November 10, 2017, meanwhile, Gimhae and Incheon International Airport and Incheon Harbor showed more intercepting pest rate than other areas. In Animal and Plant Quarantine Agency, inspector found 490 cases of intercepted pests on 32 countries including China with 116 imported goods.
        19.
        2017.05 구독 인증기관·개인회원 무료
        To obtain in vivo matured oocytes for dog cloning, serum progesterone (P4) level were employed for ovulate determination. Radioactive immunoassay (RIA) is a traditional serum hormone assay method with highly radioactivity. The aim of this study was to evaluate the reliability of RIA and to compare its canine serum P4 concentration determination accuracy to that of the electric chemiluminescence immunoassay (ECLI). To obtain in vivo matured oocytes for canine somatic cell nuclear transfer, serum P4 levels were accurately measured with both methods of RIA and ECLI. Although both methods detected similar P4 level before ovulation, the mean P4 concentration using ECLI was significantly higher than that using RIA from 3days before ovulation. Following ovulation, oocytes were collected by surgery, and a lower percentage of mature oocytes were observed using ECLI (39%) as compared to RIA (67%) if 4-8ng/ml of P4 were criteria for determination of ovulation. On other hand, high percentage of mature oocytes was observed using ECLI when 6–15 ng/mL of progesterone was criteria for ovulation determination. To determine whether in vivo oocytes obtained by ECLI method could be used for canine cloning, six canines were selected as oocyte donors and two puppies were produced after SCNT and embryo transfer. In conclusion, compared to the traditional RIA method, the ECLI method is a safe and reliable method for canine cloning.
        20.
        2015.10 구독 인증기관·개인회원 무료
        Grapholita molesta occur four times a year and Carposina sasakii occur twice a year, and both pests do damage on stone fruits such as peach, apple, plum, apricot, etc. Grapholita molesta is worldwide distributed in temperate and subtropical areas including South Korea. But, Carposina sasakii distributed in South Korea, Japan, China and Asia, and has been managed as an important import quarantine pest by the authorities of United States, Canada and Taiwan. Forecasting of both pests in Korea is currently done through the investigation of 1,000 fruits per 10 trees (100 fruits / tree) in designated peach orchard. However, this method is very difficult to observe the pest by bagging of peach and require too much time and labor. Therefore, we tried to carry out a new forecasting method by using of sex pheromone traps for newly standardized method as an alternative. Using sex pheromone trap, attractiveness of G. molesta was proved to be 2.5 > 1.5 > 0.5 m by the height and the border => outside > center by the position. Attractiveness of C. sasakii made no difference in height, but, more trapped at the center and border than outside in position at peach orchard.
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