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        검색결과 1,295

        21.
        2023.11 구독 인증기관·개인회원 무료
        The mobility of uranium (U) in various disposal environments of a deep geological repository is controlled by various geochemical conditions and parameters. In particular, oxidation state of uranium is considered as a major factor to control the mobility of uranium in most of geological environments. In this study, therefore, we investigated the geochemical behaviors of uranium in grounwater samples from natural analogue study sites located in the Ogcheon Metamorphic Belt (OMB). Groundwater samples were taken using a packer system from Boeun Hoenam-myun site and Geumsan Suyoung-ri site where several boreholes were dilled with various depths. The geochemical properties and parameters such as temperature, pH, Eh, EC, and DO were directly measured in the site using an in-line measurement method. The concentrations of major cations and anions in the groundwater samples were measured by using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) and IC (Ion Chromatography), respectively. The concentrations of trace elements including U and Th were measured by using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) The concentrations of U in the groundwater samples are very low for the Hoenammyun site (0.03~0.69 ppb) and Suyoung-ro site (0.39~1.74 ppb) even though the two sites are uranium deposits and redox conditions are weakly oxidizing. The speciation, saturation index (SI), pH-Eh (Poubaix) diagram were calculated using the Geochemist’s Workbench (GWB 9.0) program and the recent OECD/NEA thermochemical database for U. Calculation results for U speciation in the groundwater samples show that major dissolved uranium species in the groundwater samples are mainly as calcium uranyl carbonate complexes such as Ca2UO2(CO3)3(aq) and CaUO2(CO3)3 2- for almost all groundwater samples. The calculated results for SI and Poubaix diagram also show that the dominant uranium solid phase is a uranyl silicate mineral, uranophane (Ca(H2O)(UVIO2)2 (SiO2)2(OH)6), not uraninite (UIVO2). Since the determination of Eh values for natural groundwater samples is very difficult and uncertain work, we analyzed and discussed the effect of Eh on the geochemical behaviors of U in the groundwater. However, these calculation results are not consistent with the observation for U minerals in rock samples using electron microscopic techniques. Thus, we need further studies to explain the discrepancy between calculation and observation results.
        22.
        2023.11 구독 인증기관·개인회원 무료
        The natural barrier system surrounding the geological repository for high-level radioactive waste plays a crucial role in preventing or delaying the leakage of radionuclides. Therefore, the natural barrier should ensure low permeability to prevent groundwater flow into the engineered barrier system throughout the repository’s lifetime. Crystalline rock, considered as the host rock for the geological repository in Korea, exhibits low intact rock permeability, but the crystalline rock often contains the multiple discontinuities due to its high brittleness that can allow the unexpected fluid flow. Therefore, the long-term hydraulic behavior of the discontinuity should be characterized while considering additional thermal, mechanical, and chemical effects. In comparison to thermal, hydraulic, and mechanical processes, the chemical processes on the discontinuities progress relatively slowly, resulting in limited researches to include these chemical processes. This research introduces mechanisms the involving coupled thermal-hydraulic-mechanicalchemical processes focusing on the rough fracture surfaces and asperities. The chemically-induced changes in mechanical and hydraulic properties are described based on pressure solution and precipitation concepts. A comprehensive review of laboratory tests, field tests, and numerical simulations is conducted related to the chemically-induced coupled processes in fractured rock. Laboratory tests, in particular, concentrate on microscopic changes in fracture asperities induced by pressure solution to analyze chemically-induced aperture changes. The TOUGHREACT, an integral finite difference method program for thermal-hydraulic-chemical simulations, is generally employed to model the chemical response of pressure solution and precipitation on fracture surfaces. The TOUGHREACT includes a module to describe effective porosity and permeability changes based on the modified cubic law, so the real-time change of the fracture permeability can be reflected during the flow simulation. Considering the coupled thermal-hydraulic-mechanicalchemical processes of discontinuity, it becomes evident that the chemical processes under repository conditions (long-term, high temperature, and high pressure) can disturb the hydraulic performance of the natural barrier, so further research is required to characterize the chemically-induced coupled processes for assessing the long-term performance of the natural barrier system.
        23.
        2023.11 구독 인증기관·개인회원 무료
        Natural analogue studies aim to understand specific processes or to make predictions regrading formation processes or environmental conditions based on information from natural phenomena on Earth. Studying geological environments similar to the disposal system can help evaluate the longterm stability of the disposal system. These studies play a crucial role in evaluating the long-term stability of deep geological repositories (DGRs) for high-level radioactive wastes, which must remain stable for extended periods. In particular, bentonite, as a vital buffer material in DGRs, is mainly composed of montmorillonite and undergoes a transformation into zeolite under specific environmental conditions, resulting in the loss of its role as a buffer material in terms of swelling property and hydraulic conductivity. In this study, bentonite samples from Pohang Basin in Korea were investigated, revealing the presence of montmorillonite and zeolite in both outcrop and drilling core samples. While it has been known that montmorillonite and zeolites can form from volcanic glass through diagenesis or hydrothermal alteration, this study revealed that these minerals are formed under distinct environmental conditions. The outcrop samples primarily consisted of montmorillonite with minor quantities of cristobalite and amorphous silicate minerals. In contrast, the drilling core samples were composed of montmorillonite, zeolites, quartz and feldspar, indicating different mineral assemblages and characteristics between the outcrop and drilling samples. This observation suggests different environmental conditions during the mineral formation process. Therefore, various experiments and analytical methods were employed to gain a deeper understanding of the phase transformation from montmorillonite to zeolites under diverse environmental conditions
        24.
        2023.11 구독 인증기관·개인회원 무료
        Raman characteristics of various minerals constituting natural rocks collected from uranium deposits in Okcheon metamorphic zone in Korea are presented. Micro-Raman spectra were measured using a confocal Raman microscope (Renishaw in Via Basis). The focal length of the spectrometer was 250 mm, and a 1800 lines/mm grating was installed. The outlet of the spectrometer was equipped with a CCD (1,024256 pixel) operating at -70°C. Three objective lenses were installed, and each magnification was 10, 50, and 100 times. The diameter of the laser beam passing through the objective lens and incident on the sample surface was approximately 2 m. The laser beam power at 532 nm was 1.6 mW on the sample surface. Raman signal scattered backward from the sample surface was transmitted to the spectrometer through the same objective lens. To accurately determine the Raman peak position of the sample, a Raman peak at 520.5 cm-1 measured on a silicon wafer was used as a reference position. Since quartz, calcite, and muscovite minerals are widely distributed throughout the rock, it is easy to observe with an optical microscope, so there is no difficulty in measuring the Raman spectrum. However, it is difficult to identify the uraninite scattered in micrometer sizes only with a Raman microscope. In this case, the location of uraninite was first confirmed using SEM-EDS, and then the sample was transferred to the Raman microscope to measure the Raman spectrum. In particular, a qualitative analysis of the oxidation and lattice conditions of natural uraninite was attempted by comparing the Raman properties of a micrometer-sized natural uraninite and a laboratory-synthesized UO2 pellet. Significantly different T2g/2LO Raman intensity ratio was observed in the two samples, which indicates that there are defects in the lattice structure of natural uraninite. In addition, no uranyl mineral phases were observed due to the deterioration of natural uraninite. This result suggests that the uranium deposit is maintained in a reduced state. Rutile is also scattered in micrometer-sizes, similar to uraninite. The Raman spectrum of rutile is similar in shape to that of uraninite, making them confused. The Raman spectral differences between these two minerals were compared in detail.
        25.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The use of NG in the transportation sector is becoming an appealing option to diesel and gasoline fuels, presenting higher benefits. ANG technology offers a secure, cost-effective, energy-efficient strategy for the storage of NG in porous sorbents at reasonable gas densities. The major goal for its extensive utilization is the requirement of effective storage materials under practicable conditions. Recently, there has been increased attention in utilizing bio-wastes for the preparation of microporous carbons. In this contribution, our growing knowledge on the use of biobased materials and the processing strategies in an effort to predictively produce effective porous carbons appropriate for ANG technology have been reviewed. By careful literature selection, different precursors with different alternative processes to convert low-cost bio-wastes into porous carbons and achievements in methane storage are presented. To gain deeper insight into the technology, the correlation between the structural and chemical properties of materials and the factors affecting the storage performance are highlighted. The utilization of bio-wastes for the development of microporous carbons with facile methods emerged to be encouraging, which would be significant in larger scale applications. Bio-waste processing for ANG storage is valued over many other techniques, and the products are able to store substantial levels of methane. This review could help improve researchers’ evaluation of the methods as a guideline for ANG. Further studies for achieving an accomplished interconnection between the structural characteristics and the methane storage capacities with different bio-wastes and optimization strategies would be beneficial.
        6,900원
        26.
        2023.10 구독 인증기관·개인회원 무료
        Immunity is largely divided into innate immunity and adaptive immunity. We conducted a study using HongJam extract to confirm its innate immunity-enhancing effect. Our data using Natural Killer (NK) cells, which play an important role in innate immunity, confirmed that HongJam extract promotes the proliferation of NK cells and also enhances the function of NK cells to attack and destroy cancer cells. (Grant No. PJ017024022023)
        27.
        2023.10 구독 인증기관·개인회원 무료
        Seasonal occurrence and distribution of insect pests and their natural enemies were investigated in several Paprika greenhouses(different pest control histories). Even in the environmental-controlled greenhouses with natural enemies for controlling insect pests, there were differences in occurrence and distribution of insect pests and natural enemies by season. From March after planting, aphids and whiteflies(Myzus persicae and Bemisia tabaci) had partially occurred in all experimental greenhouses. During summer season, whiteflies and leaf mites primarily occurred and insect pest species occurred in this season were more diverse than the winter season. In the winter season, whiteflies predominantly occurred in both natural enemies and pesticide-treated Paprika greenhouses. Predatory mite, Amblyseius swirskii was difficult to maintain their populations under an average temperature below 18℃ and relative humidity below 60%.
        28.
        2023.10 구독 인증기관·개인회원 무료
        2022년 10월부터 2023년 5월까지 친환경 딸기재배 농가에서 점박이응애는 칠레이리애응애와 사막이리응애, 진딧물은 콜레마니진디벌을 대상으로 하는 천적처리구와 유기농자재를 사용하는 관행방제구에서 천적의 해 충 밀도억제 효과를 조사하였다. 천적처리구에서 점박이응애 성충 밀도는 잎당 1.5마리 이하, 알은 4개 이하로 관리되었고, 사막이리응애는 잎당 최대 0.4마리까지 증가하여 점박이응애 밀도억제에 많은 영향을 미친것으로 보인다. 반면, 관행방제구에서 점박이응애 밀도는 천적 방사구에 비하여 오히려 많은 발생량을 보였지만, 3월 9일부터는 사막이리응애의 증가와 유기농자재의 효과로 점박이응애 밀도는 급격하게 감소하였다. 진딧물 천적 처리구에서 진딧물 밀도는 1월부터 발생하였으며 3월 상순에 잎당 0.3마리까지 증가하였으나 이후 감소하였고, 콜레마니진디벌은 진딧물 발생이 많지 않아 3.9마리/㎡(2회) 방사하는 데 그쳤다. 한편, 관행방제구 포장의 진딧 물은 유기농자재의 영향으로 거의 발생하지 않았다.
        29.
        2023.10 구독 인증기관·개인회원 무료
        Honeybees are pollinating agent of economic importance, and a model organism for microbiome analysis. The microbiota plays a great role in honeybee health and development as such needs to be fully elucidated among Apis mellifera in Korea. using 16S rRNA gene illumina sequencing, the gut microbiota of Apis mellifera at four developmental stages under natural condition shows dysbiosis of essential microbiota, especially between the 5-days larvae and workers.
        30.
        2023.10 구독 인증기관·개인회원 무료
        The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important agricultural pests. Therefore, we screened fifteen compounds from natural products for their spatial repellent and oviposition deterrent activities against T. urticae in the laboratory by using two-choice and no-choice tests. In the bridge two-choice test, nine compounds showed the spatial repellent effects on T. urticae at 20 mg dose, resulting in reduced numbers of eggs. Among the nine compounds, at 2 mg dose, two compounds were selected as having more spatial repellent activity than the others. The two compounds also showed spatial repellent and oviposition deterrent effects in the two-choice test from hosts. In the no-choice test from a host, the spatial repellent effects of the two compounds to T. urticae were significantly stronger than that of controls. These results suggest that the findings can be used as potential agents for the prevention and population control of T. urticae in the field.
        31.
        2023.10 구독 인증기관·개인회원 무료
        The cotton aphid, Aphis gossypii glover (Hemiptera: Aphididae), is the world-wide agriculture pest and has the ability to become resistant to many pesticides. Hence, we conducted behavioral tests on apterous and alate aphids for series compounds from natural products by using a two-choice test, a no-choice test, a host choice test and electroantennography (EAG). As a result, we found 3 out of 30 compounds for apterous aphids and 2 out of 15 compounds for alate aphids, both of which showed powerful repellent effects on these aphids. In this study, we suggest that our findings could be useful and eco-friendly spatial repellents for controlling cotton aphid.
        32.
        2023.10 구독 인증기관·개인회원 무료
        한국에서 시설 딸기 해충을 방제하는 대표적인 방법은 살충제를 사용한 화학적 방법이다. 이는 농가에서 쉽게 접하고 처리 시기를 마음대로 조절할 수 있는 장점이 있지만, 방제 비용과 농업인부의 빈번한 화학살충제 노출이 큰 단점이다. 경주시 상평농원은 천적을 적극적으로 사용하는 농가로써 2020년부터 현재까지 4년간 4종의 천적 을 구매, 사육, 방사를 실시하였다. 방사한 천적은 점박이응애 방제용 칠레이리응애와 사막이리응애, 작은뿌리 파리 방제용 뿌리이리응애, 진딧물 방제용 콜레마니진딧벌이며, 농장의 규모는 재배동 1,250평, 육묘동 450평으 로 자가육묘를 하기에 1년 내내 딸기를 재배하는 농장이다. 본격적으로 천적을 활용하는 시기는 9월부터 이듬해 5월까지 약 9개월이다. 이 기간 동안 소요된 비용은 천적을 구매하고 자가사육하여 사용한 경우(154만원), 천적과 약제를 구매하여 같이 사용한 경우(240만원), 천적만 구매하여 사용한 경우(262만원), 약제만 처리(377만원) 순 으로 나타났다. 다만, 이 결과는 과학적으로 반복 및 재현 검증되지는 않았고, 각 농가의 천적과 해충의 생태에 대한 이해도와 작물 재배능력, 천적 사육능력에 따라 차이가 있을 수 있다.
        33.
        2023.10 구독 인증기관·개인회원 무료
        경북대학교 친환경농업연구센터에서는 농업인들의 효과적인 천적 활용을 증진시키기 위하여 2016년부터 경상북도 농민사관학교의 지원을 받아서 친환경천적 교육과정을 개설하고 천적 자가생산 및 현장적용 기술의 실습교육을 실시하였다. 그동안 토양 포식성 천적인 총채가시응애(Gaeolaelaps aculeifer)와 뿌리이리응애 (Stratiolaelaps scimitus), 그리고 점박이응애의 포식성 천적인 칠레이리응애(Phytoseiulus persimilis)와 사막 이리응애(Neoseiulus californicus)의 간편하고 경제적인 대량생산기술을 개발하고 그 기술을 약 180명의 농업 인에게 전수하였다. 즉, 농업인들이 스스로 천적을 자가생산하여 시설재배지에 적용함으로서 비용절감 및 청정 농산물 생산 효과를 높히는데 기여했다. 또한, 간편한 천적생산기술을 전국적으로 농업기술원, 농업기술센터, 그리고 친환경농업인단체 등 20여개 기관에 전수하였다. 최근, 경북의 농업기술센터(안동, 고령, 경주)에서 농업 인을 대상으로 천적 대량생산 시스템 보급 시범 사업을 실시하면서 뿌리이리응애 및 칠레이리응애 등의 천적 자가생산시설을 구축하고 자체적으로 생산함으로서 지속적인 천적 활용이 가능하게 되고 해충 방제 효과를 증가시킬 수 있었다. 즉, 농업인들이 직접 천적을 생산하고 활용하게 함으로서 천적농업의 성공사례가 증가하였 을 뿐만 아니라 국내 천적 공급 시스템이 다양화되어 천적농업의 활성화에 크게 기여한다고 판단한다.
        34.
        2023.10 구독 인증기관·개인회원 무료
        경북 안동의 진걸맘농장은 딸기와 쪽 농사를 주로 하고 있으며 10년 이상 친환경 무농약 농법을 인증받은 농가로서 천적을 활용하여 토경 1,000평 규모의 시설 하우스에 딸기 재배를 하고 있다. 2018-2020에 경북농민사관학교 친환경 천적과정을 통하여 천적의 자가생산 기술을 배우고 2021년부터 농가에서 직접 자가생산을 시작하였다. 그래서, 진걸맘농가는 칠레이리응애를 자가사육하여 지속적으로 딸기 재배지에 처리함으로서 점박이응애 방제에 성공한 농업인으로서 국내 첫 사례로 꼽힌다. 또한, 2022년 안동시농업기술센터에서 안전농산물 생산을 위한 천적 배양시 스템 보급 시범 사업에 선정되어 딸기 해충의 생물적 방제를 위한 뿌리이리응애, 칠레이리응애, 보리뱅커플랜트 등의 천적 배양시설 완공, 천적의 자가생산 및 성공적인 현장적용 기술로서 농산물의 지역특화, 브랜드화를 통한 농산물 가격 차별화에 크기 기여하였으며 국내 천적농업의 발전을 위해 앞장서고 있는 선도농가로 인정받고 있다.
        35.
        2023.10 구독 인증기관·개인회원 무료
        국내 천적농업이 활성화되기 위해서 토착천적을 개발하여야 한다. 토착천적들을 개발하기 위하여 시설재배 지 내에 다양한 비작물성 식물들을 확보하는 것이 필요하다. 식물의 종류가 많으면 이에 서식하는 기주곤충이 늘어나고 그 곤충들의 토착천적들이 증가한다. 이러한 시설재배지내에 식물 종다양성 확보를 위하여 재배작물 사이의 공간에 경합되지 않는 곳에는 다양한 잡초를 증식하거나 새로운 천적유지 식물을 개발하여 다양한 기주 곤충을 증식시켜야 한다. 현재 가장 많이 사용하는 것으로서 보리를 이용한 콜레마니진딧벌 천적유지식물이 개발되었지만, 그 외에도 담배, 천사의나팔 김장배추, 쑥, 소리쟁이, 냉이 등 다양한 천적유지식물들을 개발할 수 있다. 즉, 토착천적을 개발하기 위하여 생태적으로 안정된 작물재배환경을 유지하는게 필요하고 이러한 안정 된 생태계 속에서 효과적인 천적을 통한 해충방제가 이루어질 수 있다.
        36.
        2023.10 구독 인증기관·개인회원 무료
        Natural enemy insects, including predators and parasitoids, are beneficial organisms that feed upon other agricultural pests. Using natural enemy insects to suppress or prevent outbreak of pests is a key component of integrated pest management strategy. It is safe, effective, and environmentally friendly and can be applied easily to the greenhouses, filed crops and orchards. Rearing and application of natural enemy insects in biocontrol in China have a long history. As early as 1700 years ago, the predator Oecophylla smaragdina has been used for controlling many kinds of citrus pests. Up to now, more than 30 species of natural enemies that can be artificially mass produced and widely used for biological control of many kinds of pests, including caterpillars, aphids, whiteflies, thrips, leaf mites and scales in China. The annual average application area of natural enemies is over 11.34 million hectares. However, with the increasing demand of using natural enemies in biological control programs, the development of natural enemy insect industrialization still face many challenges. It is urgent to explore more effective candidate natural enemies, improve the production efficiency, increase the shelf life of products and enhance the colonization of natural enemy insects after release, and thus facilitate the commercially production and application of natural enemies. This is of great significance for comprehensively promoting the use of green prevention and control techniques for crop diseases and pests, reducing the use of chemical pesticides, ensuing the quality and safety of food and agricultural products, and ultimately promoting sustainable agricultural development.
        39.
        2023.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The invasive red swamp crayfish, Procambarus clarkii, is native to southcentral United States and northeastern Mexico. Recently, it has been being spreading in the wild in South Korea. However, its primary sources, introduction routes, establishment, and expansion in South Korea remain unclear. Here, we analyzed genetic diversity and population genetic structures of its domestic natural populations during early invasion, commercial stock from local aquaria (a suspected introduction source), and original United States population using mitochondrial COI gene sequences for 267 individuals and eight microsatellite markers for 158 individuals. Natural and commercial populations of P. clarkii showed reduced genetic diversity (e.g., haplotype diversity and allelic richness). The highest genetic diversity was observed in one original source population based on both genetic markers. Despite a large number of individuals in commercial aquaria, we detected remarkably low genetic diversity and only three haplotypes among 226 individuals, suggesting an inbred population likely originating from a small founder group. Additionally, the low genetic diversity in the natural population indicates a small effective population size during early establishment of P. clarkii in South Korea. Interestingly, genetic differentiation between natural populations and the United States population was lower than that between natural populations and aquarium populations. This suggests that various genetic types from the United States likely have entered different domestic aquariums, leading to distinct natural populations through separate pathways. Results of our study will provide an insight on the level of genetic divergence and population differentiation during the initial stage of invasion of non-indigenous species into new environments.
        4,000원
        40.
        2023.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 뇌혈류 신호를 측정할 수 있는 시변자계 기반의 비접촉식 직물센서를 설계하여 뇌혈류 신호 검출 및 감성평가의 가능성을 탐색하고자 하였다. 직물센서는 40 denier의 은사를 30합사 한 후 컴퓨터 기계 자수하여 코일 형 센서로 구현하였다. 뇌혈류 측정 실험을 위해 코일형 센서를 경동맥 부위에 부착하고, ECG (Electrocardiogram) 전극과 RSP (Respiration) 측정 벨트를 부착 및 착용하도록 하였으며, 동시에 초음파 진단기기를 사용해 도플러 초음 파 검사(Doppler Ultrasonography)를 수행하여 혈류 속도를 측정하였다. 피험자에게 Meta Quest 2를 착용시키고, 실 험을 위해 조작된 영상 시각 자극을 보여주면서 혈류 신호를 측정한 후 시각 자극에 대한 감성평가 설문지를 작성하 도록 하였다. 측정 결과, 도플러 초음파 검사를 통해 측정된 혈류 속도 신호에 변화가 생길 때 직물센서로 측정한 신호도 함께 변화하는 것으로 나타났다. 이를 통해 코일형 직물센서를 이용하여 뇌혈류활동 신호를 측정할 수 있다 는 것을 검증하였다. 또한, 감성평가를 위하여 ECG 신호와 PLL 신호(직물센서 신호)에서 추출한 HRV를 계산해서 비교한 결과, 시각 자극으로 인한 교감신경계와 부교감신경계의 활성화에 따른 비율의 변화에 대해서는 직물센서로 측정한 신호와 ECG 신호를 이용해 계산한 값이 비슷한 경향을 보이는 것으로 나타났다. 결론적으로, 본 연구에서 개발된 시변자계 기반의 코일형 직물 센서를 통해 뇌혈류 변화 측정 및 감성 모니터링이 가능할 것으로 사료된다.
        4,300원
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