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        검색결과 18

        1.
        2023.11 구독 인증기관·개인회원 무료
        Bentonite, primarily composed of montmorillonite, plays a crucial role as one of the engineering barrier materials in a deep geological repository (DGR). The advantageous properties of montmorillonite, such as its swelling capacity, low permeability, and low thermal conductivity, make it a key component as a buffer material for isolating high-level radioactive waste from the surrounding natural environment. It has been known that the stability of montmorillonite is influenced by a wide range of pressure-temperature-composition (P-T-X) conditions relevant to the DGR environment. When considering potential geological events, of notable concerns are its interactions with groundwater or seawater at elevated temperatures, leading to safety hazards within the system. In this study, therefore, we investigated the hydration and dehydration reactions of Ca-montmorillonite with saline fluids such as NaCl and KCl solutions at elevated pressures and temperatures by conducting in-situ X-ray diffraction experiments using both a capillary sample heating cell and a resistive-heated diamond anvil cell. As a result, we observed different hydration states of montmorillonite depending on the chemical composition of fluids, i.e., tri-hydrated layers in NaCl and bi-hydrated layers in KCl solutions, respectively. Furthermore, we identified that montmorillonite undergoes distinct stepwise dehydration with increasing temperature, and the dehydration temperature of montmorillonite significantly increases with increasing water pressure. Consequently, this study would provide insights into the stability of hydrated montmorillonite in a seawater-dominated fluid environment and its implications for the long-term safety of the disposal system.
        2.
        2022.10 구독 인증기관·개인회원 무료
        Concrete is used as the main engineering barrier in low and intermediate level radioactive waste disposal facilities. As the time passed, the radionuclides stored in repository may contact with groundwater and leak into the ecosystem through the rock media. In this process, the radionuclides can react with calcite via sorption or coprecipitation, because calcite is the major mineral of concrete. Under the various background conditions in repository, frequent dissolution-precipitation reactions can happen. Dissolution of Sr-coprecipitated calcite may be different from that of SrCO3(s) which can mislead the safety performance of radioactive Sr and the estimate of Sr mobility based on the solubility of SrCO3(s). Strontium is not only one of the fission products but also emits beta rays with a long half-life almost 29 years. The strontium may be released or retarded by the dissolution-precipitation reactions in repository. In this study, the dissolution of Sr-coprecipitated with respect to calcite was tested in various environment conditions. The Sr-coprecipitated calcite, (Sr,Ca)CO3(s) was synthesized by coprecipitation method in alkaline condition. The 250 mL of 0.1 M of CaCl2 solution was mixed with 250 mL of 1.14 mM SrCl2·6H2O solution. Then, independently prepared 500 mL of 0.1 M Na2CO3 solution was mixed with the mixed solution of CaCl2 and SrCl2. The precipitates could be made and they were aged for 3 days at room temperature. Then, the supernatant was separated by the centrifugation and the solid at the bottom was dried in an oven at temperature 80°C. After that, the Srcoprecipitated calcite powder was washed using the DI water several times and dried again before use. Characterization of solid powder was conducted by XRD and SEM, and the ICP-MS and ICP-AES were used to analyze the concentrations of Ca and Sr. The batch dissolution experiment was conducted with a solid-to-solution ratio of 10 g/L groundwater in polyethylene tubes. The oxidative groundwater was synthesized by simulating the chemical composition of KAERI Underground Research Tunnel (KURT) DB-3 groundwater. Different temperatures and pHs were prepared and tested for the release of Sr and Ca from the coprecipitated (Sr,Ca)CO3(s) to compare the results with the release of Sr and Ca from SrCO3(s) and CaCO3(s), respectively. Such as, these results will be used to provide better understanding of Sr release and mobility in various repository environments.
        4.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study is to analyze the impact of the level of the light-environment and the driver's visual ability on the change in the driver's perception of a forward curved section at night. The study also aims to identify factors that should be considered to ensure safety while entering curved sections of a road at night. METHODS : Data collected from a virtual driving experiment, conducted by the Korean Institute of Construction Technology (2017), were used. Logistic regression was applied to analyze the effects of changes in the light-environment factors (road surface luminance and glare) and the driver’s visual ability on a driver's perception of the road. Additionally, analysis of the moderated effect of visual ability on light-environment factors indicated that the difference in drivers’ visual abilities impact the influence of light-environment factors on their perception. A driver's ability to perceive, as a response variable, was categorized into 'failure' and 'success' by comparing the perceived distance and minimum reaction sight distance. Covariates were also defined. Road surface luminance levels were categorized into 'unlit road surface luminance' (luminance ≤ 0.1 nt) and 'lit road surface luminance' (luminance > 0.1 nt), based on 0.1 nt, which is the typical level observed on unlit roads. The glare level was categorized as 'with glare' and 'without glare' based on whether the glare was from a high-beam caused by an oncoming vehicle or not. The driver's visual ability level was categorized into 'low visual ability' (age ≥ 50) and 'high visual ability' (age ≤ 49), considering that after the age of 50, the drive’s visual ability sharply declines. RESULTS : The level of road surface luminance, glare, and driver's visual ability were analyzed to be significant factors that impact the driver's ability to perceive curved road sections at night. A driver's perception was found to reduce when the road surface luminance is very low, owing to the lack of road lighting ('unlit road luminance'), when glare is caused by oncoming vehicles ('with glare'), and if the driver's visual ability level is low owing to an older age ('low visual ability'). The driver's ability to perceive a curved section is most affected by the road surface luminance level. The effect is reduced in the order of glare occurrence and the driver's visual ability level. The visual ability was analyzed as a factor that impacts the intensity of the effect of change of the light-environment on the change of the driver's ability to perceive the road. The ability to perceive a curved section deteriorates significantly in 'low visual ability' drivers, aged 50 and above, compared to drivers with 'high visual ability,' under the age of 49, when the light-environment conditions are adverse with regard to the driver’s perception (road surface luminance: 'lit road surface luminance'→'unlit road surface luminance,' glare: 'without glare'→'with glare'). CONCLUSIONS : Supplementation, in terms of road lighting standards that can lead to improvements in the level of light-environment, should be considered first, rather than the implementation of restrictions on the right of movement, such as restricting the passage of low visual ability or aging drivers who are disadvantageous in terms of gaining good perception of the road at night. When establishing alternatives so that safety on roads at night is improved, it is necessary to consider improving drivers' perception by expanding road lighting installation. The road lighting criteria should be modified such that the glare caused by oncoming traffic, which is an influential factor in the linear change in perception, and the level of light-environment thereof are improved.
        4,900원
        5.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기존 온·습도 센서와 여러 가스센서에 의해 측정 및 제어되는 돈사환경제어시스템에 돼지의 체온조 절행동에 근거한 생체정보를 이용하여 외부 환경정보를 보정한다면 보다 정밀한 축사 환경제어를 할 수 있다. 이를 위한 본 연구는 ICT기술을 접목한 스마트돈사의 정밀환경제어를 위한 기초연구로 획득된 이 미지를 바탕으로 돼지의 행동특성을 3가지로 분류하기 위한 영상처리시스템 알고리즘을 제시하고자 한 다. 공시재료는 실험돈사에서 사육되고 있는 육돈용 자돈(F2, 36~40kg) 3마리를 이용하였으며, 영상처 리를 수행하고자 천정에 설치된 카메라를 통해 획득된 이미지를 이용하였다. 영상처리를 위한 프로그램 은 Visual Studio C과 다양한 영상처리를 위해 개발된 오픈 소스 라이브러리인 OpenCV Library를 이 용하여 구현하였다. 행동분류 알고리즘은 각 돼지의 중심점 데이터, 돼지가 차지하는 면적, 돼지 사이 의 거리를 구하고자 전처리를 수행한 이미지를 RGB 색상계에서 YCrCb 색상계로 변환하였으며, 히스토 그램 평활화(Histogram Equalization), cvBlob함수를 사용하여 Labeling 알고리즘을 수행하였다. 영상 처리 결과, 검증 이미지를 대상으로 군집형태 A로 판단된 결과는 면적만 고려한 것과 거리와 면적을 같 이 고려하였을 때 인식률 95%를 나타내었다. 군집형태 B의 경우 면적만을 고려하였을 경우 65%, 면적 과 거리를 모두 고려하였을 경우 95%로 나타났다. 군집형태 C의 경우 면적만을 고려하였을 경우 25%, 면적과 거리를 모두 고려하였을 경우 100%로 나타나 환경정보 보정자료로 활용이 가능한 것으로 판단 되었다.
        4,000원
        6.
        2017.04 구독 인증기관 무료, 개인회원 유료
        This study is intended to look into the effects of employee's working environment on work loss and productivity in overseas construction sites of Korean construction companies. To achieve this, a survey was empirically carried out to overseas construction site experts. The results were as follows. The weight by 5 loss factors of overseas construction projects showed that project management environment was the highest, followed by construction company environment, owner environment, government support environment and entry country environment, which the biggest work loss factor was the project management section. The weight by loss factors of entry country environment showed that local environment was highest, followed by social environment, economical environment, political environment and cultural environment. In other words, awareness and management of weak social bases, which are not well-institutionalized as properties of most preferred loss, are important in that local environment of new entry countries is the most important thing. As for the above-mentioned findings, the most important project management of overseas construction projects will need to take advantage and have know-how for construction companies' ability to cope with a crisis or the most preferred management and loss prevention of owner environment, government support environment and entry country environment.
        4,000원
        7.
        2013.06 구독 인증기관 무료, 개인회원 유료
        이 연구는 사회복지사의 근로환경 실태를 파악하기 위하여 서울시 사회복지사협회 정책위원회의 발표자료를 근거로 하여 사회복지사들의 근로형태 및 임금, 근로시간 등의 근로조건과 근로환경, 윤리적 및 종교적 갈등, 클라이언트 폭력, 신체 및 정신적 어려움 등에 초점을 두어 살펴보고, 현재 사회복지 현장에서 시행되고 있는 사회복지사의 처우에 관한 실태조사를 통해 사회복지사들의 사기진작과 서비스의 질적 향상을 위한 방안을 모색해 보고자 하였다. 먼저, 근로조건에 대해서는 전반적으로 보통 수준 이하의 낮은 수준으로 조사되었고, 일․가정 양립을 위한 기관의 인식개선 및 지원책 마련이 필요한 것으로 나타났으며, 종교 편향적, 비윤리적 기관운영에 대한 개선책의 마련이 필요한 것으로 조사되었다. 또한 클라이언트의 폭력과 직장내 폭력으로부터 보호책의 마련이 시급한 것으로 파악되었으며, 전체적으로 사회복지사의 인권수준이 매우 열악한 것으로 조사되었다. 연구 결과 사회복지사의 처우개선을 위한 실질적 대책 마련이 시급하고, 사회복지시설의 보조금 지원방식의 개선과 예산지원의 확대가 필요하다고 사료된다.
        5,700원
        8.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        저일조 조건에서 고추와 토마토 유묘의 생육에 미치는 몇 가지 친환경농자재의 이용효과를 검토하고자 하였다. 친환경농자재는 미생물제재, 효소제, 아미노산제 3종을 이용하였고 30% 차광조건에서 토마토와 고추를 육묘하였으며, 육묘용 상토 종류에 따른 차이를 보기위해 일반 원예용(유비)상토와 무비상토를 비교하였다. 토마토와 고추 모두 무비상토에서는 효소제와 아미노산제 처리에 의해 묘의 생육이 양호하였으나, 미생물제재 처리는 대조구와 차이가 없었다. 유비상토에서는 친환경농자재 처리에 의한 생장촉진효과가 나타나지 않았다. 차광처리에 의하여 묘의 건물중은 감소하고, 엽면적은 다소 증가하는 경향을 보였으나, 친환경농자재의 처리에 의한 생육촉진효과는 없었다. 정식 후 토마토 1화방의 개화소요일수 및 착과절위를 조사한 결과, 무비상토의 경우 효소제 및 아미노산제 처리구에서 개화소요일수가 3~4일 적었으나, 착과절위는 차이가 없었다. 다만 차광조건에서 착과절위가 낮아지는 경향을 보였다. 유비상토의 경우는 친환경농자재 처리나 차광 유무에 따른 개화소요일수나 착과절위의 차이가 없었다. 고추는 무비상토에서 차광에 관계없이 효소제 및 아미노산제 처리구에서 건물중이 증가하였으나 미생물제재 처리구에서는 효과가 없었다. 유비상토는 친환경 농자재의 처리효과가 없었다. 따라서 시판되고 있는 효소제와 아미노산제는 무비상토에서 생육촉진효과가 있었으나, 미생물제재 처리는 처리효과가 없었고, 양분이 함유된 상토에서는 친환경농자재의 처리효과가 없었다. 또 차광에 의한 저일조 조건에서 친환경농자재의 혼용 처리에 의한 토마토와 고추 유묘의 생육촉진효과는 없었다.
        4,000원
        9.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 묘의 생육을 최대화하기 위하여 생육 단계를 임의로 구분하고 각 단계 별 적정 환경 조건을 확립함에 목적을 두었다. 생육 단계는 총 20일의 배양기간을 6일(1단계), 7일(2단계), 7일(3단계)의 3단계로 구분하였다. 첫 번째 단계는 활착기로서 환경 처리 별 생육에 큰 차이가 나타나지 않았다. 높은 환경 조건에 의한 잎의 장해를 고려하였을 때, 80μmmol·m-2·s-1 의 PPFD 및 대기 중의 CO2 농도가 적합하였다. 두 번째 단계에서는 PPFD 및 CO2 조건이 높아짐에 따라 건물 중을 중심으로 부분적으로 향상되었다. 에너지 효율과 생육을 고려할 때, 160μmmol·m-2·s-1 의 PPFD와 700μmmol·mol-1의 CO2가 적합할 것으로 생각되었다. 세 번째 단계에서는 PPFD 및 CO2 농도가 높아짐에 따라 유의적으로 생육이 향상되었으며, 잎 및 마디의 발달상태도 현저히 향상되었다. 따라서 보다 적극적으로 생육증진을 고려할 때, 320μmmol·m-2·s-1 PPFD와 1800μmol·mol-1의 CO2가 적합할 것으로 생각되었다. 생육 단계별 환경 조절은 초기단계에 상대적으로 낮은 조건을 유지하고 후기단계에서 충분한 조건을 제공함으로써 건전한 묘를 생산할 수 있고 에너지 및 물질의 투입량을 절약할 수 있다.
        4,000원
        10.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        With the effectuation of Kyoto Protocol, one of the important movement throughout the world is reducing the emission of greenhouse gas which is the main reason of making global warming. The actual factor of greenhouse gas is CO2, and in year of 2002 20% of total CO2 emission was produced only through transportation throughout the South Korea. In the contrary, the recycling of municipal wastes in South Korea was 44.0% in 2002, but it will be targeted upto 53.5% in 2011. All of these show environment-conscious logistics should be implemented together throughout the each stage of distribution with the development of product and service. This study applied survey research for the activities affecting to the emission of CO2 and packaging wastes produced from transportation and packaging stages in logistics area. For this, survey questionary was constructed with five specific areas - strategy, transportation & distribution, custody, packaging, and information. Based on the 148 returned survey questionaries, this study analyzed 52 categories and finally suggests necessary modal shift, collaboration & co-operation in logistics, LCA(life-cycle assessment), and other promoting policies for the environment-conscious logistics in effective way.
        4,300원
        11.
        2016.10 KCI 등재 서비스 종료(열람 제한)
        Localized atmospheric conditions between multi-reference stations can bring the tropospheric delay irregularity that becomes an error terms affecting positioning accuracy in network RTK environment. Imbalanced network error can affect the network solutions and it can corrupt the entire network solution and degrade the correction accuracy. If an anomaly could be detected before the correction message was generated, it is possible to eliminate the anomalous satellite that can cause degradation of the network solution during the tropospheric delay anomaly. An atmospheric grid that consists of four meteorological stations was used to detect an inhomogeneous weather conditions and tropospheric anomaly applied AWSs (automatic weather stations) meteorological data. The threshold of anomaly detection algorithm was determined based on the statistical weather data of AWSs for 5 years in an atmospheric grid. From the analytic results of anomaly detection algorithm it showed that the proposed algorithm can detect an anomalous satellite with an anomaly flag generation caused tropospheric delay anomaly during localized atmospheric conditions between stations. It was shown that the different precipitation condition between stations is the main factor affecting tropospheric anomalies.
        12.
        2016.10 KCI 등재 서비스 종료(열람 제한)
        Extreme tropospheric anomalies such as typhoons or regional torrential rain can degrade positioning accuracy of the GPS signal. It becomes one of the main error terms affecting high-precision positioning solutions in network RTK. This paper proposed a detection algorithm to be used during atmospheric anomalies in order to detect the tropospheric irregularities that can degrade the quality of correction data due to network errors caused by inhomogeneous atmospheric conditions between multi-reference stations. It uses an atmospheric grid that consists of four meteorological stations and estimates the troposphere zenith total delay difference at a low performance point in an atmospheric grid. AWS (automatic weather station) meteorological data can be applied to the proposed tropospheric anomaly detection algorithm when there are different atmospheric conditions between the stations. The concept of probability density distribution of the delta troposphere slant delay was proposed for the threshold determination.
        13.
        2013.09 KCI 등재 서비스 종료(열람 제한)
        The Historic Cultural Environment Conservation Areas around Chosun Royal Tombs in Gyeonggi Province are larger than those around other Cultural Assets, so more efficient management tools on the Areas should be needed. This study aims to suggest the directions of policy to modify the existing management tools by analyzing the spatial extent and alteration standards of the 12 Historic Cultural Environment Conservation Areas around Chosun Royal Tombs in Gyeonggi Province. The results of this study are as follows: First, in most cases, the spatial extents of the Areas are 500m, but the spatial extents should be precisely classified in Gyeonggi Ordinance of Cultural Assets Protection, and be excluded according to the layout of Protection Areas and roads. And the outside view from the inside is more important in Chosun Royal Tombs, so the areas on the axis of the view must be controled by considering the development density(bulk or height of buildings). Second, the same zoning areas must be classified as the same section of the Area allowing for equity, and Finally, the Current Conditions Permission Criteria should be actualized to take into account the difference between the development densities of zoning araes and the Criteria.
        14.
        2010.03 KCI 등재 서비스 종료(열람 제한)
        The present study explores time and spatial thermal environment for Daegu, which is a city built on a basin area, according to varying land cover conditions of the earth's surface by analyzing data derived from meteorological observation and satellite images. The study has classified land use by utilizing MODIS satellite images and analyzed land surface temperature. Also, by using data acquired from automatic weather system, the study has evaluated the effects of atmospheric heating caused by city pavements by analyzing the sensible heat flux between the city's land surface and the atmosphere.The results are as follows. 1) Classification of land use in the Daegu area shows 46.64% of urban and built-up area, 1.39% of watersides, 35.19% of forest, 11.43% of crops, and 5.37% grasslands. 2) During the weekdays throughout the year, the land surface temperature was high for Dalseogu, Bukgu, and Seogu regions where industrial complexes could be found. Comparatively, lower temperature could be observed in the woodlands. 3) While the land surface temperature displayed the effects of pushing air upwards during the weekdays in urban areas, the reverse was true for forest regions. During the night, the temperature did not exert any significant influence on air movement.
        16.
        2008.10 KCI 등재 서비스 종료(열람 제한)
        인삼은 연작지 재배가 불가능하고 주산지의 우량 예정지 고갈로 인하여 제주도를 제외하고 국내 전국에서 재배하고 있다. 지역별 기후형태가 상이함에도 불구하고 동일한 해가림 구조로 재배하고 있어 일부지역에서 피해가 발생하고 있어 지역에 적합한 표준 해가림 재배기술이 필요하다고 생각된다. 따라서, 본 연구는 남부지역(밀양, 나주, 해남)에서의 적정 해가림구조를 밝히고자 실시하였다. 실험은 2008년 부산대학교 부속농장(밀양)에 묘삼을 이식하였고 해가림 시설은 차광망(검정 차광망), 차광판(비누수 광반사 차광판), 차광지+망(청색 비누수차광지에 검정색 차광망), 차광지(청색 비누수차광지)를 후주연결식으로 설치하여 삼집내 광량과 온도를 측정하였고(Li-cor사의 LI-2000) 광합성속도와 엽록소 형광반응은 생육하고 있는 2년생 인삼을 이용하여 Li-cor의 LI-6400으로 조사하였다. 해가림 자재별 광량은 차광판과 차광지에서 높은 경향을 보였으며, 차광판의 경우 전주에서의 반사광의 유입으로 삼집내 광량이 높은 경향이 있었고, 차광지의 경우 투광량이 높아 광량이 높게 나타냈다. 차광지+망과 차광망에서는 광량이 낮은 경향이었다. 온도는 차광판이 가장 낮은 경향이었는데 이는 직접광이 삼집내로 투과되지 못한 원인으로 사료되며, 다음으로 차광망, 차광지+망, 차광지 순으로 높은 경향을 보였다. 차광지의 경우 투광량이 높아 인삼에서 고온장해가 생기는 현상이 나타났다. 광합성의 경우, 광강도가 증가함에 따라 광합성속도가 증가하는 경향이 있었고, 해가림 자재에 따라 비교하면 차광판에서 높은 경향을 보였으며, 다음으로 차광망과 차광지+망이 높았고, 차광지에서 낮은 경향이었다. 엽록소 형광반응에서 Fo는 차광판에서 낮은 경향이었으며, 다음으로는 차광망, 차광지+망, 차광지 순으로 높은 경향을 보였다. Fv/Fm에서는 차광판에서 높았고, 차광망, 차광지+망, 차광지 순으로 낮은 경향이 있었다. ETR은 차광판에서 가장 높은 경향이 나타냈으며, 다음으로 차광망, 차광지+망, 차광지로 낮은 경향을 보였다.
        17.
        2008.09 KCI 등재 서비스 종료(열람 제한)
        The effects of inorganic salts, inoculum concentration, aeration rate and shaking speed on insoluble phosphate solubilization by Pseudomonas fluorescens RAF15 were investigated. Soluble phosphate production was dependent on the presence of MgCl₂·6H₂O and MgSO₄·7H₂O in the medium. Supplementation of medium with 0.01% CaCl₂·2H₂O and 0.01% NaCl slightly increased soluble phosphate production. The optimal medium compositions for the solubilization of insoluble phosphate by P. fluorescens RAF15 were 1.5% glucose, 0.005% urea, 0.3% MgCl₂·6H₂O, 0.01% MgSO₄·7H₂O, 0.01% CaCl₂·2H₂O and 0.01% NaCl, respectively. Optimal inoculum concentration was 2.0%(v/v). Maximum soluble phosphate production was obtained with 20-50 ml/250-ml flask and 200 rpm of shaking speed, respectively. The addition of EDTA decreased cell growth and soluble phosphate production.
        18.
        2002.03 KCI 등재 서비스 종료(열람 제한)
        A biosurfactant-producing microorganism was isolated from activated sludge by enrichment culture when grown on a minimal salt medium containing n-hexadecane as a sole carbon source. This microorganism was identified as Pseudomonas sp. and it was named Pseudomonas sp. EL-G527. It's optimal culture condition is 2% n-hexadecane, 0.2% NH4NO3, 0.3% KH2PO4, 0.3% K2HPO4, 0.02% MgSO4ㆍ7H2O, 0.0025% CaCl2ㆍ6H2O, 0.0015% FeSO4ㆍ7H2O in 1ℓ distilled water and initial pH 7.0. Cultivation was initiated with a 2% inoculum obtained from starter cultures grown in 30 ㎖ of the same medium in 250 ㎖ flask. They were cultivated at 30 ℃ in reciprocal shaking incubator and the highest biosurfactant production was observed after 4 days.