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        검색결과 61

        2.
        2023.10 구독 인증기관·개인회원 무료
        Honey bees are crucial pollinators for agricultural and natural ecosystems, but are experiencing heavy mortality in Korea due to a complex suite of factors. Extreme winter losses of honey bee colonies are a major threat to beekeeping but the combinations of factors underlying colony loss remain debatable. Finding solutions involves knowing the factors associated with high loss rates. To investigate whether loss rates are related to Varroa control and climate condition, we surveyed beekeepers in korea after wintering (2021–2022 to 2022–2023). The results show an average colony loss rate of 46%(2022) and 17%(2023), but over 40% colony loss before wintering at 2022. Beekeepers attempt to manage their honey bee colonies in ways that optimize colony health. Disentangling the impact of management from other variables affecting colony health is complicated by the diversity of practices used and difficulties handling typically complex and incomplete observational datasets. We propose a method to 1) Varroa mite population Control by several methods , and 2) Many nursing bee put in hive before wintering.
        4.
        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
        5.
        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
        7.
        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
        9.
        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
        10.
        2018.10 구독 인증기관·개인회원 무료
        The purpose of the present study was to evaluate if main domestic vector mosquitoes, Aedes albopictus as a diurnal species and Culex pipiens as a nocturnal species, have correlation between reflecting luminous intensity of colors and preference for blood feeding activity. Laboratory evaluations were performed and the mosquito preferences were compared to three different color brightness such as light, primary, and dark for five fundamental color series including red, yellow, green, blue, and purple. The test bodies selected for these experiments were BioGents Sentinel traps (BG traps) with 20g dry ice in each falcon tube, which covered outside of the traps attached with three different luminous intensities such as light, primary, and dark for each different color of paper sheets. In each experiment, a pair of BG traps was placed 0.6 m away from each other in a 1.8 m x 3.7 m x 1.8 m screened enclosure. The enclosure maintained at 26±2℃, 65±5% RH, and 100 lux illumination. Evaluations were performed for two hours between 10:00 and 16:00 for each 25 Ae. ablopictus females and 15 hours from 18:00 to 9:00 for each 25 Cx. pipiens females. Each experiment was replicated four times. As a result, reflecting luminous intensity (L-value) affected and correlated negatively to the preference of the two mosquito species but the fundamental colors, green-red (a-value) and blue-yellow (b-value) were not correlated significantly to the preference (p=0.05). Aedes ablopictus females were preferred for feeding activity more to lower L-values of the colors and correlated negatively between color preference of the mosquitoes and the L-values such as r = -0.584 (p=0.003) for red, r = -0.606 (p=0.002) for yellow, r = -0.620 (p=0.001) for green, and r = -0.463 (p=0.023) for blue except purple (r = -0.129; p=0.549). Similarly, Cx. pipiens females were correlated negatively such as r = -0.590 (p=0.002) for red, r = -0.564 (p=0.005) for yellow, r = -0.687 (p=0.000) for green, r = -0.623 (p=0.001) for blue, and r = -0.689 (p=0.000). In conclusion, the color brightness were negatively correlated to the feeding activity of the two vector mosquito species but not the wavelength of visible ray. Also, the mosquito females preferred significantly darker ones in the same color series (p<0.05) except purple for Ae. ablopictus females.
        11.
        2018.10 구독 인증기관·개인회원 무료
        The purpose of the present study was to evaluate if main domestic vector mosquitoes, Aedes albopictus as a diurnal species and Culex pipiens as a nocturnal species, have color preference for blood feeding activity. Laboratory evaluations were performed and compared to assess color attractiveness using seven fundamental colors including black, white, red, yellow, green, blue, and purple. The test bodies selected for these experiments were BioGents Sentinel traps (BG traps) with 20g dry ice in each falcon tube, which covered outside of the traps attached with each different color of vinyl sheets. In each experiment, a pair of BG traps was placed 0.6 m away from each other in a 1.8 m x 3.7 m x 1.8 m screened enclosure. The enclosure maintained at 26±2℃, 65±5% RH, and 100 lux illumination. Evaluations were performed for two hours between 10:00 and 16:00 for each 25 Ae. ablopictus females and 15 hours from 18:00 to 9:00 for each 25 Cx. pipiens females. The attraction rates were determined by a series of 42 simultaneous pairs of sample counts of the number of mosquitoes caught in the traps at every 30 minutes. As a result, black traps collected the largest number of Ae. albopictus as a mean 0.7 of 1.0 for Mosquito Preference Index (MPI), followed closely by red, blue, and purple (MPIs, 0.6) that were significantly higher (p<0.05) than those of green (MPI, 0.5), white (MPI, 0.3), and yellow (MPI, 0.2). Similarly, the MPIs for Cx. pipiens were significantly higher at black and red traps (MPIs, 0.7) but the MPIs (0.3) at white and yellow traps were significantly lower than those of the other colors.
        12.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 교육용 코딩퍼즐게임의 모델링에 대하여 분석하고 이를 바탕으로 유·아동에게 효과적인 형식의 코딩게임을 구현하며, 그 적합도를 평가한다. 시중에 출시된 여러 코딩퍼즐게임들의 핵심체계가 되는 학습개념, UI체계, 게임시스템의 특징과 문제점을 분석한 후, 이를 바탕으로 새로운 학습용 퍼즐게임을 개발한다. 개발된 게임의 학습개념, UI체계, 게임시스템을 소개하고, 개발된 게임을 실제로 적용한 어린이집 모의수업과 실습수업 진행과정에 대하여 기술한다. 실제로 게임을 실행하게 되는 아이들에게 있어서 적정 수준의 단계가 어느 정도인지를 판단하기 위해 개발된 게임에 대해서 어린이집 방과후 학습교사들의 평가로 개념의 시각화, 직관적 요소, 난이도 조절의 세 항목에 대하여 평가과정(각각 5점 만점)을 거쳤다. 그 결과로 개발된 게임은 직관적 요소에서 4.08점, 난이도 조절에서 3.72점, 개념의 시각화에서 3.44점을 나타내어 모두 보통 이상의 결과를 나타냈다. 개념의 시각화를 위해서는 개념 자체를 활용할 수 있는 포맷의 적용, 직관적 요소로 스테이지의 시작과 종료를 알리는 명확한 요소의 적용, 난이도 조절로는 연습문제 챕터의 적용이 주요한 것으로 나타났다.
        4,000원
        13.
        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.
        14.
        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.
        15.
        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.
        16.
        2017.10 구독 인증기관·개인회원 무료
        Ethyl formate has been used for the control of insect pests by fumigation. However, there were not many reports toshow its target site of fumigant toxicity on insect pests since its first use in the agricultural industry. In the present study,we showed the presumable target sites of ethyl formate fumigation in insect pests using Myzus persicae nymphs. Afterethyl formate fumigation, the nymphs of this species were collected and the changes at the biochemical and molecularlevel were determined. The activity of cytochrome c oxidase (COX) was approximately two-fold higher after ethyl formatefumigation. In addition, the expression levels of acetylcholinesterase (AChE) decreased gradually with increasing ethylformate concentration. These two findings suggested that COX and AChE might be the major target sites of ethyl formatefumigation. In addition to these results, the analysis of lipid content using MALDI-TOF MS/MS identified 9 phospholipidsdifferently generated 2-fold higher in the ethyl formate-treated nymphs than that in the control nymphs, thereby leadingto changes in cell membrane composition in M. persicae nymphs. Therefore, the ethyl formate fumigation caused lethaleffects on M. persicae nymphs by changing COX activity, AChE gene expression, and phospholipid production.
        18.
        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.
        19.
        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.
        20.
        2015.10 구독 인증기관·개인회원 무료
        Calepitrimerus vitis (Nalepa) is a grapevine pest and distributed worldwide. This study was conducted to identify grapevine damage related to density of C. vitis and to suggest an effective control time. The damaged flower buds displayed retarded growth and became dried up, and symptoms of damaged leaves such as malformed and bronzed leaves were observed. Flower cluster and leaves were collected and density of the grape rust mite were observed by using a washing and sieving method. The highest mean density (±SE) of C. vitis was found to be 672.6±112.9 per flower cluster with mid-level damage, and 450.1±66.5 per 2 leaves was found on the damaged leaves. These severe damage symptoms were observed in the early spring, and the density of the grape rust mite was significantly higher as 80 times in damaged vineyard than in the undamaged at the early growth stages of the grapevine. To determine the emergence time of the grape rust mite from lower part of a winter bud the ratio of density of C. vitis on upper-bud to lower-bud was observed. On 13 April 2015, 80% of the grape rust mites were observed on upper-bud where the mite could feed at the bud burst stage. Therefore, once the symptoms of damaged flower clusters and leaves are observed, acaricides should be sprayed before inflorescence emergence, and at the early growth stage between bud burst and leaf development in following year. This would allow the decrease of the density of C. vitis in early spring, and the progression of severe damage could be prevented.
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