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        검색결과 22

        1.
        2023.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we focus on the improvement of data quality transmitted from a weather buoy that guides a route of ships. The buoy has an Internet-of-Thing (IoT) including sensors to collect meteorological data and the buoy’s status, and it also has a wireless communication device to send them to the central database in a ground control center and ships nearby. The time interval of data collected by the sensor is irregular, and fault data is often detected. Therefore, this study provides a framework to improve data quality using machine learning models. The normal data pattern is trained by machine learning models, and the trained models detect the fault data from the collected data set of the sensor and adjust them. For determining fault data, interquartile range (IQR) removes the value outside the outlier, and an NGBoost algorithm removes the data above the upper bound and below the lower bound. The removed data is interpolated using NGBoost or long-short term memory (LSTM) algorithm. The performance of the suggested process is evaluated by actual weather buoy data from Korea to improve the quality of ‘AIR_TEMPERATURE’ data by using other data from the same buoy. The performance of our proposed framework has been validated through computational experiments based on real-world data, confirming its suitability for practical applications in real- world scenarios.
        4,300원
        3.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh- energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600oC.
        4,000원
        4.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To meet rapidly changing market demands, manufacturers strive to increase both of productivity and diversity at the same time. As a part of those effort, they are applying flexible manufacturing systems that produce multiple types and/or options of products at a single production line. This paper studies such flexible manufacturing system with multiple types of products, multiple Bernoulli reliability machines and dedicated buffers between them for each of product types. As one of the prevalent control policies, priority based policy is applied at each machines to select the product to be processed. To analyze such system and its performance measures exactly, Markov chain models are applied. Because it is too complex to define all relative transient and its probabilities for each state, an algorithm to update transient state probability are introduced. Based on the steady state probability, some performance measures such as production rate, WIP-based measures, blocking probability and starvation probability are derived. Some system properties are also addressed. There is a property of non-conservation of flow, which means the product ratio at the input flow is not conserved at the succeeding flows. In addition, it is also found that increased buffer capacity does not guarantee improved production rate in this system.
        4,200원
        5.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research examines deep learning based image recognition models for beef sirloin classification. The sirloin of beef can be classified as the upper sirloin, the lower sirloin, and the ribeye, whereas during the distribution process they are often simply unified into the sirloin region. In this work, for detailed classification of beef sirloin regions we develop a model that can learn image information in a reasonable computation time using the MobileNet algorithm. In addition, to increase the accuracy of the model we introduce data augmentation methods as well, which amplifies the image data collected during the distribution process. This data augmentation enables to consider a larger size of training data set by which the accuracy of the model can be significantly improved. The data generated during the data proliferation process was tested using the MobileNet algorithm, where the test data set was obtained from the distribution processes in the real-world practice. Through the computational experiences we confirm that the accuracy of the suggested model is up to 83%. We expect that the classification model of this study can contribute to providing a more accurate and detailed information exchange between suppliers and consumers during the distribution process of beef sirloin.
        4,000원
        6.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서 흰목이버섯의 추출조건별 추출수율과 기능성 성분의 함량을 비교하여 최적 추출조건을 분석하였으며, 모든 분석에서 R²이 0.9331~0.9462로 유의성을 보이는 것을 확인하였다. 각 독립변수에 따른 추출수율과 ergothioneine, β-glucan 성분을 분석한 결과 추출수율은 추출온도와 추출시료농도에 반비례했으며, 추출시간에는 큰 영향이 없었다. Ergothioneine 성분은 온도가 증가할수록 증가하며, 추출시간은 4.33 h가 가장 높았고 시료량에 큰 영향이 없었다. β-glucan 성분은 온도가 증가할수록 감소했으며, 추출시간에 큰 영향이 없었고 시료량이 21.2 mg/mL에서 가장 높았다. 모든 종속변수의 최대 독립변수는 온도 60 o C, 추출시간 4.33 h, 추출시료농도 16.6 mg/mL에서 추출수율 24.9%, ergothioneine 성분함량 66.8 ug/g, β-glucan 성분함량 34.9 g/100 g으로 나타났다.
        4,000원
        7.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to evaluate the improvement in exercise endurance by Hovenia dulcis fruit hot water extract (HDWE) for the potential application as a functional food material. The effect was based on the evaluation of the forced-swimming capacity and changes in biochemical parameters in mice. Six-week-old mice were classified into four groups based on a randomized block design: the negative control group, the HDWE 50 mg/kg body weight group, the HDWE 200 mg/kg body weight group, and the 1-octacosanol 50 mg/kg body weight group (n=8 mice per group). The swimming exercise time in the HDWE-50 group was increased at 545±43 sec compared to the control group at 263±28 sec. The HDWE-200 fatigue indicators, lactate acid and ammonia content, decreased to 4.99±0.33 mg/mL and 0.63±0.05 mg/mL, respectively. In addition, the content of glycogen in the liver and muscle tended to increase in the group administered HDWE but was not significant. Likewise, the LDH and glucose contents were increased compared to the control group. The muscle damage indicators ALT (52.7±2.6 U/L) and AST (42.5±5.2 U/L) tended to decrease compared to the control group (76.4±10.2 U/L).
        4,000원
        10.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 2013년도에 강원도의 옥수수 재배지들을 조사하고, 밑둥썩음병에 걸린 옥수수로부터 Fusarium균을 분리하였다. 분리한 병원균은 translation elongation factor 1 alpha(EF-1 alpha) 유전자 분석과 형태학적 조사를 통해 확인하였으며, F. subglutinans가 밑둥썩음병의 주요 원인균임을 확인하였다. F. subglutinans KWFS-1의 화학적 방제를 위해, 6개의 살균제와 하나의 살충제를 선발하여 항균효과를 검정하였다. 추천농도로 약제를 사용하였을 때, tebuconazole, difenoconazole, fluquinconazole이 각각 균사생장을 무처리구에 비해 64%, 60%, 55% 억제하는 것으로 나타났다. 반면 에 hymexazol, azoxystrobin, clothianidin, benomyl은 각각 20%, 37%, 35%, 23%를 억제하는 효과를 보였다. 포자생장 억제에서 benomyl, tebuconazole, difenoconazole, fluquinconazole은 포자생장을 완전히 억제하였지만 hymexazol, azoxystrobin, clothianidin이 첨가된 배지에서는 포자생장으로 나타난 균총이 각각 1.1 mm, 2.1 mm, 4.1 mm의 직경크기를 보여 농약별 포자생장 억제효과가 상이함을 보였다.
        4,000원
        11.
        2012.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Chalcogenide-based semiconductors, such as CuInSe2, CuGaSe2, Cu(In,Ga)Se2 (CIGS), and CdTe have attracted considerable interest as efficient materials in thin film solar cells (TFSCs). Currently, CIGS and CdTe TFSCs have demonstrated the highest power conversion efficiency (PCE) of over 11% in module production. However, commercialized CIGS and CdTe TFSCs have some limitations due to the scarcity of In, Ga, and Te and the environmental issues associated with Cd and Se. Recently, kesterite CZTS, which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of 104cm-1, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTS-based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. The recent development of kesterite-based CZTS thin film solar cells is summarized in this work. The new challenges for enhanced performance in CZTS thin films are examined and prospective issues are addressed as well.
        4,800원
        12.
        2012.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        석조문화재의 풍화훼손도를 평가하기 위해 초음파속도를 이용하는 방법은 현장적용 및 풍화도 평가가 용이하여 널리 사용되고 있다. 이 방법은 풍화가 진행되면 초음파 속도가 감소하는 특성을 이용해 신선암과 풍화암의 초음파속도 차이를 이용하여 풍화등급을 산정한다. 그러나 풍화등급 산정에서 신선암의 초음파속도를 암석의 산출지역과 관계없이 고정값(5,000 m/s)으로 사용하기 때문에 우리나라와 같이 동일한 암종에서도 다양한 속도가 나타나는 경우 많은 문제가 발생되고 있다. 따라서 본 연구에서는 우리나라 석조문화재를 구성하는 대표 암종에 대하여 20종의 시편과 60개의 코어시료를 획득해 신선암의 초음파속도를 측정하여 데이터베이스(DB)를 구축하고 이를 보고하였다. 이 결과, 동일한 암종인 화강암 내에서도 초음파속도가 3,118에서 5,380 m/s까지 다양하게 나타나며 이를 무시하고 고정값을 사용할 경우 풍화등급 산정에 많은 오차를 발생시킬 수 있음을 확인하였다. 다음으로 측정 오차에 대한 보정을 위해, 현장측정에서 사용하는 두 가지 방법(직접법과 간접법)에 의해 속도를 측정하고 지역별 암종에 따른 보정계수를 산출하였는데 그 범위는 1.31에서 1.76까지 다양하게 나타났다. 그 외 측정온도, 장비운영자에 따른 초음파속도의 차이를 확인한 결과 그 차이가 오차범위 내에 있어 풍화도 평가에 미치는 영향은 크지 않은 것으로 나타났다. 마지막으로 본 연구에서 얻어진 초음파속도 DB와 측정보정계수를 실제 석조문화재인 봉황리 마애불상군에 적용한 결과, 풍화지수는 0.3으로 기존의 방법보다 0.1 정도 낮게 평가되었으며 풍화등급 또한 기존의 방법이 "상당히 풍화"로 판별하는 것에 비해 "중간정도의 풍화"로 차이가 나타났다. 동일한 문화재를 대상으로 한 다른 연구결과에서 중간정도의 풍화등급을 제시하고 있어 본 연구의 결과가 보다 정확한 것으로 확인되었다. 따라서 본 연구에서 제시한 방법은 보다 정확한 풍화지수의 산정과 그에 따른 보존대책을 수립하는데 기여할 것으로 기대된다.
        4,500원
        13.
        2019.10 서비스 종료(열람 제한)
        본 논문에서는 혼합골재 종류 변화 및 CGS 치환율에 따른 콘크리트의 내구성 특성을 분석하였다. 실험결과 CGS 치환율이 증가할수록 AE공기량의 영향으로 내동해성은 저하, 조직치밀화의 영향으로 탄산화는 지연되는 것으로 나타났다.
        14.
        2019.10 서비스 종료(열람 제한)
        본 연구에서는 선별파쇄 골재 등 부순 골재에 포함된 토분함유량 규정치를 정하는 연구의 일환으로써 골재 토분이 모르타르의 기초적 특성에 미치는 영향을 분석하였다. 토분함유량이 증가할수록 유동성과 휨강도는 감소하고, 공기량은 증가하며 압축강도는 1 % 전후에서 증가하는 경향도 나타났으나 전반적으로 감소하였다.
        15.
        2019.04 서비스 종료(열람 제한)
        In this study, the mechanical properties of concrete incorporating blast furnace slag with 60 % were analyzed according to CBS-Dust replacement rate. Results indicate that replacement of more than 10 % of CBS-Dust have a positive effect on reducing waste disposal costs and strength improvement
        16.
        2018.10 서비스 종료(열람 제한)
        In this study, the temperature correction strength (Tn) was conducted to propose (Tn) according to the management age of structural concrete that is separated from the average curing temperature of 4°C to 17°C in cold conditions. After reviewing the strength difference of the concrete using fly ash as a combined material at W/C 50%, the temperature correction strength (Tn) is proposed. The temperature correction strength was proposed to compensate for differences with standard curing conditions due to decrease in curing temperature from 28th, 42nd, 56th and 91st of the models interpreted as equivalent age methods.
        17.
        2018.10 서비스 종료(열람 제한)
        This study is a basic study to CGS, which originates from the IGCC, as fine aggregate for concrete. The study measured density, water absorption ratio, solid volume percentage for grain shape, fineness modulus, grading curve of physical properties of fine aggregate. As a result, the density and solid volume percentage for grain sheet were found to be satisfactory in the aggregate for content (KS F 2527).Water evaluation ratio, fitness modulus, and grinding curve did not meet KS standards. Therefore, it is deemed necessary to adjust the grain size through sieving in case of fineness modulus and grinding curve.
        18.
        2018.10 서비스 종료(열람 제한)
        This study was conducted to improve the economy, quality, and load of Soil paving concrete by using waste materials such as Oystery and Dolomitic to solve strength reduction and durability reduction caused by hardening agents in Korea. According to the results of the study, for the curing expenses, the Fine part agreement (FC) and the Furnace slag power lower (BS) are 5:5, It was possible to verify that the best results were obtained in terms of the quality of cement mortar when the natural organic lime and dolomitic lime were mixed at a ratio of 5:5.
        19.
        2018.10 서비스 종료(열람 제한)
        In this study, the shear strength according to the width of the web was assessed by using the Waste styrofoam as hollow material without reprocessing. The concrete's design strength was set to 24MPa and the web width was 50mm, 100mm, and 150mm as variables. Shear strengths of KCI increased from 111.2% to 203.9%.
        20.
        2018.04 서비스 종료(열람 제한)
        In this study, the correlation between the durometer and the proctor penetration resistance tester, which is considered to be efficient in determining the setting time in a simple portability for soil and concrete utilizing organic lime (H) and Goto lime (G), is used. The results of the study show a high correlation between the portable hardness meter, the durometer and the proctor penetration resistance test period. Therefore, it is expected that the durometer will be useful for the measurement of setting time and the time limit.
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