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        검색결과 596

        10.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to fabricate composites with high thermal conductivity using diglycidyl ether of bisphenol-A (DGEBA), incorporating carbon fiber cloth (CFC) and graphene as reinforcing agents. Notably, the dispersion of graphene within the DGEBA matrix was enhanced through surface modification via a silane coupling agent. The effects of CFC and graphene addition on the impact strength, thermal conductivity, and morphology of the composites were examined. The experimental results showed that the incorporation of 6 wt% CFC resulted in a substantial (16-fold) increase in impact strength. Furthermore, the introduction of 6 wt% CFCs along with 20 wt% graphene led to a remarkable enhancement in thermal conductivity to 5.7 W/(m K), which was approximately 22 and 4 times higher than the intrinsic thermal conductivities of pristine DGEBA and the CFC/DGEBA composite, respectively. The increased impact strength is ascribed to the incorporation of CFC and silane-modified graphene. Additionally, the gradual increase in thermal conductivity can be attributed to the enhanced interaction between the acidic silane-modified graphene and the basic epoxy–amine hardener within the system studied.
        4,000원
        11.
        2024.04 구독 인증기관·개인회원 무료
        The Euonymus defoliator moth, Pryeria sinica Moore (Lepidoptera: Zygaenidae), is a pest that causes considerable damage to the Euonymus genus, especially Euonymus alatus and Euonymus japonicus. The biological characteristics of P. sinica have been studied in China, Japan, Taiwan, and the United States, but there has been no research conducted on this species in Korea. Also, P. sinica has two dormant phases in each generation, one as eggs in winter and the other as pupae in summer. Our purposes are to study the biological characteristics of Korean populations of P. sinica and to examine the effects of temperature and photoperiod on summer diapause. The biological characteristics were investigated in laboratory conditions (25 ± 1 ℃, 65 ± 1% R.H., 16L:8D) and the number of eggs in an egg mass, developmental periods and mortality rate in each larvae stage, and adults’ life span were determined. The results showed that 190.7 ± 31.64 eggs were contained in one egg mass and it took 25.57 ± 0.61 days from 1st larval stage to the pre-pupal stage. P. sinica has 4 larval stages and each stage took 4.28 ± 0.21, 6.2 ± 0.55, 6.02 ± 0.68, and 8.93 ± 0.88 days. The mortality rate of larvae peaked at 22.5% in 3rd larval stage. The adults’ life span was 4.67 ± 0.97 days in males and 4.61 ± 1.82 days in females. To study summer diapause, we divided pupae into 4 groups. Both low temperature and short daytime were effective in shortening the pupal stage. The pupal stage was the shortest in group D (122.12 ± 1.24 days), in which the initial condition was 25 ℃-16L:8D and the altered condition was 16 ℃ -12L:12D, and the longest in group A (161.92 ± 3.15 days, 25 ℃-16L:8D). These data could be utilized to propose the optimal timing for controlling the population of P. sinica.
        12.
        2024.04 구독 인증기관·개인회원 무료
        Harlequin ladybird (Harmonia axyridis (Pallas, 1773)) is an invasive species originating from Asia, posing a potential threat to the ecosystem and the wine industry in New Zealand due to wine taint, although it can also be a useful biocontrol agent. In this study, the response profiles of antennal olfactory receptor neurons (ORNs) to 32 plant volatiles were examined in male and female H. axyridis, using the single sensillum recording technique. Various types of ORNs were identified from four types of olfactory sensilla in both male and female H. axyridis, with no sexual dimorphism. The most abundant type of sensilla contained two ORNs exhibiting highly specialized responses to methyl benzoate and β-caryophyllene, respectively. Another type of sensilla also contained two specialized ORNs, one responsive to geranyl acetate and the other to some aromatic compounds such as 2-phenylethanol, benzyl acetate, methyl benzoate, and methyl phenylacetate. In contrast, two other types of sensilla contained broadly tuned ORNs, one containing ORN(s) responsive to six-carbon alcohols such as (Z)-3-hexen-1-ol, 1-hexanol, and isomers of 2-hexen-1-ol as well as some other non-alcohol green leaf volatiles, and the other containing ORN(s) exhibiting responses to β-myrcene, geraniol, linalool, nerol, benzyl acetate, and methyl phenylacetate. This study suggests that H. axyridis possesses a set of ORNs specialized for specific plant volatiles, providing insights into the olfactory communication system of this species and potential volatiles to be used for trapping this insect.
        13.
        2024.04 구독 인증기관·개인회원 무료
        The box tree moth (BTM, Cydalima perspectalis Walker) is a pest that infests various plants within the Buxus genus. Although a specific parasitoid wasp species associated with the BTM has been observed in the Republic of Korea, no research on this species has been published. Here we describe the fundamental biological and morphological characteristics of this parasitoid. We placed the wasp under the genus Eriborus (Hymenoptera: Ichneumonidae: Campopleginae). Eriborus sp. parasitizes within the living host body, with one wasp emerging from each host. The parasitism rate in collected BTM populations was 33.1%. The emergence rate was 87.1%, with all emerging adults being females, resulting in a sex ratio of 0. The pupal period averaged 9.5 days, and the adult lifespan averaged 10.5 days. Eriborus sp. parasitized BTM larvae from the first to the fourth instar and reproduced by parthenogenesis. Eriborus sp. exhibited morphological differences compared with previously reported Eriborus species in Korea, particularly in the length of the ovipositor sheath. In addition, the proportion of the highest similarity in nucleotide sequences of mitochondrial cytochrome oxidase I DNA was only 94.53%, rendering species identification using GenBank’s mt cytochrome c oxidase 1 DNA sequences unfeasible. These data suggest Eriborus sp. could be used as a biological control agent for managing BTM infestations.
        14.
        2024.04 구독 인증기관·개인회원 무료
        Our study examined a total of 60 dead wood samples (Quercus spp.), collecting 30 samples each in summer and winter, and measured various environmental variables in the field. These samples were classified into three decay classes: fresh, intermediate, well-decayed. We sampled saproxylic beetles within the collected dead wood using emergence traps. Conducted a cluster analysis to explore their relationships of saproxylic beetle and environmental variables. Our results revealed that season and decay class were significant environmental variables affecting saproxylic beetle communities. These results highlight the sensitivity of saproxylic beetles to fluctuations of environment and climate. In summary, our study highlights the intricate relationships between environmental variables and saproxylic beetles and suggests that different types of dead wood should be maintained in forests.
        16.
        2024.04 구독 인증기관·개인회원 무료
        The Korea Forest Service has designated seven alpine tree species—Abies koreana, A. nephrolepis, Juniperus chinensis, Picea jezoensis, Pinus pumila, Taxus cuspidata, and Thuja koraiensis—as threatened with extinction in Korea. In 2023, we conducted a study on the seasonal occurrence of insect pests, focusing mainly on two coleopteran taxa (Cerambycidae and Scolytinae) and two hemipteran taxa (Aphrophoridae and Cicadellidae) in subalpine forests dominated by A. koreana, A. nephrolepis, Picea jezoensis, Thuja koraiensis, and Taxus cuspidata. We utilized three types of traps—Malaise trap, Lindgren funnel trap, and window trap—in eight investigation locations in Korea. In this presentation, we present the study results and discuss the effects of insect pests on alpine coniferous trees in Korea.
        17.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Animal experiments have demonstrated the effectiveness of fermented rice germ and soybean extracts in lowering blood alcohol concentration. A compound primarily derived from fermented soybean extract constitutes the principal component of DA-5521, an experimental dietary substance examined in this study. We investigated the possible hangover-alleviating effects of DA-5521 in individuals aged 19 to 50 who had previously experienced hangovers. Moreover, we enrolled 22 participants who met the eligibility criteria and conducted a double-blind, randomized, placebo-controlled crossover trial. Six hours after alcohol consumption, the test group exhibited a statistically significant reduction in blood acetaldehyde concentration compared with the placebo group. Further, our results displayed significantly lower levels in the DA- 5521 group at 0.50 and 0.75 h post-ingestion and substantially lower peak breath alcohol concentration compared to the placebo group. These findings confirm that consumption of DA-5521 can significantly ameliorate hangover symptoms by diminishing blood acetaldehyde concentration and reduce breath alcohol concentration.
        4,200원
        19.
        2023.11 구독 인증기관·개인회원 무료
        Chelating agents, such as EDTA, NTA, and citric acid, possess the capacity to establish complexes with radionuclides, potentially enhancing the migration of such radionuclides from the disposal sites. Hence, quantification of these chelating agents in radioactive wastes is required to ensure secure disposal protocols. The determination of chelating agents in radioactive wastes is mainly composed of two steps, e.g. extraction and detection. However, there are little information on the extraction of the chelators in various radioactive wastes. We endeavored to optimize the extraction conditions for citric acid (CA) found within concrete, a prevalent component in the context of dismantled waste materials. Given the inherent high solubility of CA in water, we applied an aliquot of deionized water to the concrete and conducted a one-hour ultrasonic leaching procedure to facilitate chelate extraction. Subsequently, following the preparation of the concrete leachate via vacuum filtration and centrifugation to yield a clarified solution, we quantified the concentration of CA within the solution using Ion Chromatography (IC). To enhance leaching efficiency, we examined the % recovery variation with respect to the pH of the leaching solution. The optimized extraction method will be applied to diverse chelating agents and radioactive waste categories.
        20.
        2023.11 구독 인증기관·개인회원 무료
        Alpha activities can be used for categorization, transportation, and disposal of radioactive waste generated from the operation of nuclear facilities including nuclear power plants. In order to transport and dispose of such low- and intermediate-level radioactive waste (LILW) to the Wolsong LILW Disposal Center (WLDC) at Gyeongju, the gross alpha concentration of an individual drum should be determined according to the acceptance criteria. In addition, when the gross alpha concentration exceeds 10 Bq/g, the inventory of the comprising alpha emitters in the waste is to be identified. Gross alpha measurements using a proportional counter are usually straightforward, inexpensive, and high-throughput, so they are broadly used to assay the total alpha activity for environmental, health physics, and emergency-response assessments. However, several factors are thoughtfully considered to obtain a reliable approximate for the entire alpha emitters in a sample, which include the alpha particle energy of a particular radionuclide, the radionuclide that is used as a calibration standard, the uniformity of film in a planchet, time between sample collection and sample preparation, and time between sample preparation and counting. Korea Atomic Energy Research Institute (KAERI) have evaluated the inventory of radionuclides in low-level radioactive waste drums to send every year hundreds of them to the WLDC. In this presentation, we revisit the gross alpha measurement results of the drums transported to WLDC in the past few years and compare them with the concentrations of alpha emitters measured from alpha spectrometry and gamma spectrometry. This study offers an insight into the gross alpha measurement for radioactive waste regarding calibration source, self-absorption effect, composition of alpha emitters, etc.
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