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        검색결과 1,593

        21.
        2024.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bearing-shaft systems are essential components in various automated manufacturing processes, primarily designed for the efficient rotation of a main shaft by a motor. Accurate fault detection is critical for operating manufacturing processes, yet challenges remain in sensor selection and optimization regarding types, locations, and positioning. Sound signals present a viable solution for fault detection, as microphones can capture mechanical sounds from remote locations and have been traditionally employed for monitoring machine health. However, recordings in real industrial environments always contain non-negligible ambient noise, which hampers effective fault detection. Utilizing a high-performance microphone for noise cancellation can be cost-prohibitive and impractical in actual manufacturing sites, therefore to address these challenges, we proposed a convolution neural network-based methodology for fault detection that analyzes the mechanical sounds generated from the bearing-shaft system in the form of Log-mel spectrograms. To mitigate the impact of environmental noise in recordings made with commercial microphones, we also developed a denoising autoencoder that operates without requiring any expert knowledge of the system. The proposed DAE-CNN model demonstrates high performance in fault detection regardless of whether environmental noise is included(98.1%) or not(100%). It indicates that the proposed methodology effectively preserves significant signal features while overcoming the negative influence of ambient noise present in the collected datasets in both fault detection and fault type classification.
        4,500원
        22.
        2024.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Myxomatous mitral valve disease (MMVD) in dogs is a heart disease that is characterized by histopathologic changes in cardiomyocytes, which ultimately result in valve degeneration and blood regurgitation due to structural changes in the heart valves. A number of studies have been conducted with the objective of identifying prognostic factors that may influence the prognosis of dogs with MMVD. Nevertheless, there is a paucity of research examining the factors that predict MMVD stage progression as defined by the American College of Veterinary Internal Medicine. The objective of this study was to examine whether there are factors associated with stage progression within one year of diagnosis in dogs diagnosed with subclinical MMVD (stage B1 or B2) using physical examination findings, clinicopathologic biomarkers, and echocardiographic markers. This is a retrospective study of veterinary practice performed at Chungbuk National University Animal Hospital. The electronic medical record of the hospital was searched to obtain clinical records of canine patients diagnosed with subclinical MMVD over an 11-year period. For each patient cohort, a logistic regression analysis was conducted. The variables were initially selected using the backward elimination method, and the optimal logistic regression model was determined by removing the independent variables with the largest variance inflation factor. Among the independent variables examined in this study, heart murmur intensity was identified as a statistically significant predictor of stage progression within one year for subclinical MMVD, a finding that aligns with those of previous studies. No other independent variables were found to be significantly associated with subclinical MMVD stage progression. This is the inaugural exploratory study to concentrate on blood test results, a relatively straightforward and quantifiable test result that can be readily obtained in primary care veterinary clinics, among the factors that may be associated with the progression of subclinical MMVD stages.
        4,000원
        23.
        2024.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The AlSi10Mg alloy has garnered significant attention for its application in laser powder bed fusion (L-PBF), due to its lightweight properties and good printability using L-PBF. However, the low production speed of the L-PBF process is the main bottleneck in the industrial commercialization of L-PBF AlSi10Mg alloy parts. Furthermore, while L-PBF AlSi10Mg alloy exhibits excellent mechanical properties, the properties are often over-specified compared to the target properties of parts traditionally fabricated by casting. To accelerate production speed in L-PBF, this study investigated the effects of process parameters on the build rate and mechanical properties of the AlSi10Mg alloy. Guidelines are proposed for high-speed additive manufacturing of the AlSi10Mg alloy for use in automotive parts. The results show a significant increase in the build rate, exceeding the conventional build rate by a factor of 3.6 times or more, while the L-PBF AlSi10Mg alloy met the specifications for automotive prototype parts. This strategy can be expected to offer significant cost advantages while maintaining acceptable mechanical properties of topology-optimized parts used in the automobile industry.
        4,000원
        32.
        2024.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study investigated a method of synthesizing a pitch suitable for making activated carbon using fluid catalytic crackingdecant oil (FCC-DO), a high-purity carbon precursor from oil refining. We kept the reaction time and catalyst amount constant while varying the temperature to investigate its impact on pitch synthesis and the resulting physical and activation properties. Previous research established that materials added during pitch synthesis can affect the properties of both the pitch and resulting activated carbon. This study examined the addition of polyethylene terephthalate (PET) to FCC-DO-based pitch. The results indicated significant changes in properties with PET addition and temperature variation that ensured stable activated carbon quality. At temperatures of 390 °C or higher, the specific surface area of the activated carbon stabilized between 2680 and 2740 m2/ g. Waste PET, a recyclable plastic, was chosen due to its compatibility and thermodynamic suitability for pitch synthesis. Importantly, adding PET didn't generate additional waste or degrade the physical properties of the activated carbon.
        4,000원
        33.
        2024.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        장미과의 과일 및 관상용 식물은 세계적으로 경제적, 원예적 가치가 뛰어나다. 장미과의 뱀딸기는 관상 및 약용 작물로써 이용가치가 매우 높은데, 증식방법이 마련되어 있지 않은 실정 이다. 뱀딸기의 종자 종자발아 특성을 조사하기 위해 내부형태 관찰, 수분흡수실험, 온도 별 배양, move-along test, GA3처리 실험을 수행하였다. 뱀딸기 종자는 탈리시점부터 성숙한 배를 지닌다. 수분흡수실험 결과, 침지 3시간만에 종자 무게가 초 기무게 대비 100% 이상 증가하였다. 온도 별 배양 실험 결 과, 25/15, 20/10, 15/6, 5, 25, 20, 15°C에서 각각 8주간 배양하였을 때 88, 71, 61, 12, 89, 39, 17%로 나타났다. Move-along test의 T125/15°C(12주)→20/10°C(4주)→ 15/6°C(4주)→5°C(12주)]에서 12주차까지 72%가 발아하였고 T2[4°C(12주)→15/6°C(4주)→20/10°C(4주)→25/15°C(12주)] 에선 20/10°C까지 발아하지 않았고 25/15°C에 도달하고 나서 발아하여 최종발아율은 16%로 나타났다. GA3처리구에선 배양 3주차에 발아를 시작한 반면에 대조구에선 배양 4주차부터 발 아하였다. 따라서 한반도 자생 뱀딸기 종자는 PD로 분류하였다. 뱀딸기속과 Potentilla속 식물은 서로 근연관계이고, 종간의 종 자휴면에 차이가 나타나 종자휴면 특성에 분화가 일어난 것으로 판단된다.
        4,000원
        34.
        2024.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The alfalfa weevil (Hypera postica) is an important pest that causes significant damages to alfalfa crops, reducing yield and quality, but there’s a solution. This research had two main goals to evaluate the efficacy of insecticides available in Korea for alfalfa weevil control and to provide data for pest management studies. The experiment, conducted from 2023 to 2024 at the National Institute of Animal Science in Cheonan, Republic of Korea, included four treatment plots: control (CON), early-occurrence (EAR), mid-occurrence (MID), and late-occurrence (LAT). It also included two frequency plots with primary and secondary insecticide using 50% fenitrothion emulsion, which made it truly comprehensive study. The primary insecticide was applied at the first observation of the alfalfa weevil larvae, with subsequent secondary applications at specified intervals. The results showed that two-times insecticide applications significantly reduced larvae populations and increased yield and nutrient content compared to a single application. Specifically, control rates ranged from 94 to 94.7% on the third day after treatment and from 72.2 to 93.4% on the seventh day. Plots with two applications had higher yields and crude protein content. The study concluded that the timing and frequency of insecticide applications are critical to maximizing alfalfa yield and quality, emphasizing the importance of optimized application strategies for effective pest control.
        4,000원
        35.
        2024.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to contribute to resolving the critical issue of weed management in newly established alfalfa fields, study has been conducted on effective herbicide use. The study evaluated the impact of various domestically available foliar herbicides on alfalfa phytotoxicity, weed control, yield, and nutritive value. The experiment was designed in a randomized complete block design with four treatments. Alfalfa ‘SW 5615’ seeded in the spring of 2024 on a 1 ha field (March 18), with herbicide treatments including fluazifop-P-butyl (FPB), bentazone (BEN), and a mixture of these herbicides (MIX). Herbicide efficacy, alfalfa yield, and nutritive value were assessed 30 days post-application. Results indicated that the MIX treatment achieved superior weed control comparable to hand weeding (HW), although it exhibited higher phytotoxicity, requiring extended recovery periods. While MIX led to lower overall yield, it enhanced alfalfa purity, resulting in higher crude protein (CP) content and relative feed value (RFV) compared to other treatments. The study concludes that despite the potential for increased phytotoxicity, mixed herbicide treatments could offer a strategic advantage in enhancing the quality of alfalfa feed through effective weed management, thereby improving CP and RFV, critical factors for the nutritional value of alfalfa. These findings provide valuable insights for optimizing weed management practices in alfalfa cultivation, suggesting that mixed herbicide application, although associated with increased phytotoxicity on the plants, could improve the overall feed quality by reducing weed competition.
        4,000원
        36.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We aimed to evaluate the effectiveness of ensemble optimal interpolation (EnOI) in improving the analysis of significant wave height (SWH) within wave models using satellite-derived SWH data. Satellite observations revealed higher SWH in mid-latitude regions (30o to 60o in both hemispheres) due to stronger winds, whereas equatorial and coastal areas exhibited lower wave heights, attributed to calmer winds and land interactions. Root mean square error (RMSE) analysis of the control experiment without data assimilation revealed significant discrepancies in high-latitude areas, underscoring the need for enhanced analysis techniques. Data assimilation experiments demonstrated substantial RMSE reductions, particularly in high-latitude regions, underscoring the effectiveness of the technique in enhancing the quality of analysis fields. Sensitivity experiments with varying ensemble sizes showed modest global improvements in analysis fields with larger ensembles. Sensitivity experiments based on different decorrelation length scales demonstrated significant RMSE improvements at larger scales, particularly in the Southern Ocean and Northwest Pacific. However, some areas exhibited slight RMSE increases, suggesting the need for region-specific tuning of assimilation parameters. Reducing the observation error covariance improved analysis quality in certain regions, including the equator, but generally degraded it in others. Rescaling background error covariance (BEC) resulted in overall improvements in analysis fields, though sensitivity to regional variability persisted. These findings underscore the importance of data assimilation, parameter tuning, and BEC rescaling in enhancing the quality and reliability of wave analysis fields, emphasizing the necessity of region-specific adjustments to optimize assimilation performance. These insights are valuable for understanding ocean dynamics, improving navigation, and supporting coastal management practices.
        4,600원
        37.
        2024.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        많은 연구에 따르면 Tenebrio molitor은 유충 단계에서 플라스틱을 섭취할 수 있다고 보고되었다. 이 연구의 목적은 T. molitor 유충의 성장과 발달에 발포폴리스티렌 섭취가 미치는 영향을 조사하는 것이다. 밀기울을 섭취한 유충의 성장률은 발포폴리스티렌을 섭취한 유충의 성장률보다 더 좋았고(p < 0.001) 발포폴리스티렌을 섭취한 유 충의 번데기로 전환되는 기간은 밀기울을 섭취한 유충의 번데기로 전환되는 기간보다 더 빨랐다(p < 0.001). 하지만 두 처리구간 생존율은 유의미한 차이가 없었다(p = 0.786). 이 결과에 따르면 발포폴리스티렌을 섭취한 유충은 체중 감소와 짧은 발육기간이 특징이지만 생존하는 것에는 문제가 없었다. 따라서 우리는 T. molitor가 플라스틱 폐기물 의 지속 가능하고 친환경적인 제거를 위한 주요 자원이라는 결론을 내렸다.
        4,000원
        38.
        2024.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The aggressive scaling of dynamic random-access memory capacitors has increased the need to maintain high capacitance despite the limited physical thickness of electrodes and dielectrics. This makes it essential to use high-k dielectric materials. TiO2 has a large dielectric constant, ranging from 30~75 in the anatase phase to 90~170 in rutile phase. However, it has significant leakage current due to low energy barriers for electron conduction, which is a critical drawback. Suppressing the leakage current while scaling to achieve an equivalent oxide thickness (EOT) below 0.5 nm is necessary to control the influence of interlayers on capacitor performance. For this, Pt and Ru, with their high work function, can be used instead of a conventional TiN substrate to increase the Schottky barrier height. Additionally, forming rutile-TiO2 on RuO2 with excellent lattice compatibility by epitaxial growth can minimize leakage current. Furthermore, plasma-enhanced atomic layer deposition (PEALD) can be used to deposit a uniform thin film with high density and low defects at low temperatures, to reduce the impact of interfacial reactions on electrical properties at high temperatures. In this study, TiO2 was deposited using PEALD, using substrates of Pt and Ru treated with rapid thermal annealing at 500 and 600 °C, to compare structural, chemical, and electrical characteristics with reference to a TiN substrate. As a result, leakage current was suppressed to around 10-6 A/cm2 at 1 V, and an EOT at the 0.5 nm level was achieved.
        4,000원
        39.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The development of thermoelectric (TE) materials to replace Bi2Te3 alloys is emerging as a hot issue with the potential for wider practical applications. In particular, layered Zintl-phase materials, which can appropriately control carrier and phonon transport behaviors, are being considered as promising candidates. However, limited data have been reported on the thermoelectric properties of metal-Sb materials that can be transformed into layered materials through the insertion of cations. In this study, we synthesized FeSb and MnSb, which are used as base materials for advanced thermoelectric materials. They were confirmed as single-phase materials by analyzing X-ray diffraction patterns. Based on electrical conductivity, the Seebeck coefficient, and thermal conductivity of both materials characterized as a function of temperature, the zT values of MnSb and FeSb were calculated to be 0.00119 and 0.00026, respectively. These properties provide a fundamental data for developing layered Zintl-phase materials with alkali/alkaline earth metal insertions.
        4,000원
        40.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Aflatoxin B1 (AFB1) is a toxic metabolite generated by Aspergillus species and is commonly detected during the processing and storage of food; it is considered a group I carcinogen. The hepatotoxic effects, diseases, and mechanisms induced by AFB1 owing to chronic or acute exposure are well documented; however, there is a lack of research on its effects on the intestine, which is a crucial organ in the digestive process. Dogs are often susceptible to chronic AFB1 exposure owing to lack of variation in their diet, unlike humans, thereby rendering them prone to its effects. Therefore, we investigated the effects of AFB1 on canine small intestinal epithelial primary cells (CSIc). Methods: We treated CSIc with various concentrations of AFB1 (0, 1.25, 2.5, 5, 10, 20, 40, and 80 μM) for 24 h and analyzed cell viability and transepithelial-transendothelial electrical resistance (TEER) value. Additionally, we analyzed the mRNA expression of tight junction-related genes (OCLN, CLDN3, TJP1, and MUC2), antioxidant-related genes (CAT and GPX1), and apoptosis-related genes (BCL2, Bax, and TP53). Results: We found a significant decrease in CSIc viability and TEER values after treatment with AFB1 at concentrations of 20 μM or higher. Quantitative polymerase chain reaction analysis indicated a downregulation of OCLN, CLDN3, and TJP1 in CSIc treated with 20 μM or higher concentrations of AFB1. Additionally, AFB1 treatment downregulated CAT , GPX1, and BCL2. Conclusions: Acute exposure of CSIc to AFB1 induces toxicity, and exposure to AFB1 above a certain threshold compromises the barrier integrity of CSIc.
        4,000원
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