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        검색결과 131

        23.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to investigate the effect of isolated lactic acid bacteria (LAB) on the quality of high moisture rye silage. Rye forage (Secale cereale L.) was harvested at the heading stage (27.3% of dry matter (DM)) and cut into approximately 3-5 cm lengths. Then, the forage divided into 4 treatments with different inoculants: 1) No additives (CON); 2) Lactobacillus brevis strain 100D8 at a 1.2 x 105 colony-forming unit (cfu)/g of fresh forage (LBR); 3) Leuconostoc holzapfelii strain 5H4 at a 1.0 x 105 cfu/g of fresh forage (LHO); and 4) Mixture of LBR and LHO (1:1 ratio) applied at a 1.0 x 105 cfu/g of fresh forage (MIX). About 3 kg of forage from each treatment was ensiled into a 20 L mini-bucket silo in quadruplicate for 100 days. After silo opening, silage was collected for analyses of chemical compositions, in vitro nutrient digestibilities, fermentation characteristics, and microbial enumerations. The CON silage had the highest concentrations of neutral detergent fiber and acid detergent fiber (p = 0.006; p = 0.008) and a lowest in vitro DM digestibility (p < 0.001). The pH was highest in CON silage, while lowest in LBR and MIX silages (p < 0.001). The concentrations of ammonia-N, lactate, and acetate were highest in LBR silage (p = 0.008; p < 0.001; p < 0.001). Propionate and butyrate concentrations were highest in CON silage (p = 0.004; p < 0.001). The LAB and yeast counts were higher in CON and LHO silages compare to LBR and MIX silages (p < 0.001). However, the mold did not detect in all treatments. Therefore, this study could conclude that L. brevis 100D8 and Leu. holzapfelii strain 5H4 can improve the digestibility and anti-fungal activity of high moisture rye silage.
        4,000원
        24.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Predicting remaining useful life (RUL) becomes significant to implement prognostics and health management of industrial systems. The relevant studies have contributed to creating RUL prediction models and validating their acceptable performance; however, they are confined to drive reasonable preventive maintenance strategies derived from and connected with such predictive models. This paper proposes a data-driven preventive maintenance method that predicts RUL of industrial systems and determines the optimal replacement time intervals to lead to cost minimization in preventive maintenance. The proposed method comprises: (1) generating RUL prediction models through learning historical process data by using machine learning techniques including random forest and extreme gradient boosting, and (2) applying the system failure time derived from the RUL prediction models to the Weibull distribution-based minimum-repair block replacement model for finding the cost-optimal block replacement time. The paper includes a case study to demonstrate the feasibility of the proposed method using an open dataset, wherein sensor data are generated and recorded from turbofan engine systems.
        4,500원
        25.
        2022.05 구독 인증기관·개인회원 무료
        High-intensity focused ultrasonic (HIFU) decontamination technology to decontaminate complex metal radioactive waste was developed and verified. Ultrasonic decontamination technology is a method widely used in this field, but its energy strength is weak, so it cannot be applied to fixed contamination. The HIFU developed in this study can eliminate a wide range of fixed contamination due to the advantage of maintaining a high frequency while having hundreds of times the energy intensity compared to conventional general ultrasonic method. In addition, there is a merit in that there is no work that generates a lot of secondary wastes such as chemical decontamination method or threatens the safety of workers. In particular, high ultrasonic energy is transmitted to curved parts and inside pipes that cannot be decontaminated with blasting method, so various types of metal wastes can be treated with the HIFU method. In this study, the performance of the HIFU was verified for zirconium chips, and the radioactivity after decontamination was reduced to less than MDA in all subjects.
        30.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was aimed to estimate the effect of ensiling period and bacterial inoculants on chemical compositions and fermentation characteristics on rye silage harvested at delayed stage. Rye (Secale cereale L.) was harvested after 20 days of heading stage (29.4% dry matter, DM). The harvested rye forage was applied with different inoculants following: applications of distilled water (CON), Lactobacillus brevis (LBB), Leuconostoc holzapfelii (LCH), or mixture of LBB and LCH at 1:1 ratio (MIX). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 50 (E50D) and 100 (E100D) days in triplicates. The E50D silages had higher in vitro digestibilities of DM (IVDMD, p<0.001) and neutral detergent fiber (IVNDFD, p=0.013), and lactate (p=0.009), and acetate (p=0.011) than those of E100D, but lower pH, lactic acid bacteria (LAB), and yeast. By inoculant application, LCH had highest IVDMD and IVNDFD (p<0.05), while MIX had highest lactate and lowest pH (p<0.05). The CON and LCH in E50D had highest LAB and yeast (p<0.05), whereas LBB in E100D had lowest (p<0.05). Therefore, this study concluded that LCH application improved the nutrient digesbility (IVDMD and IVNDFD) of lignified rye silage, and longer ensiling period for 100 days enhanced the fermentation characteristics of silage compared to ensiling for 50 days.
        4,000원
        35.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to estimate the effect of different cutting lengths on fermentation characteristics and aerobic stability of whole crop rice (WCR) silage. The WCR was harvested at the yellow ripe stage (43.7%, DM), and then cut at 5 (R05), 10 (R10), and 20 cm (R20) of the theoretical length of cut with no cut WCR (R60). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 150 days in quadruplicates. The cutting lengths were not affected the chemical compositions of WCR silage (p > 0.05). The pH (p < 0.001) and concentration of ammonia-N (p = 0.022) in WCR silage were increased linearly with the increase of cutting length. The concentration of lactate had quadratic effect (p = 0.007), which was highest in R20 silage (p < 0.05). The concentration of acetate was increased linearly (p = 0.014), but the concentration of butyrate was decreased linearly (p = 0.033). The lactic acid bacteria count was decreased linearly (p = 0.017), and yeast count had quadratic effect (p = 0.009), which was the highest in R20 silage (p < 0.05). Aerobic stability had strong quadratic effect (p < 0.001), which was the highest in R20 silage (p < 0.05). In conclusion, R60 silage had highest pH by a linear increase of ammonia-N concentration and led to low aerobic stability. While R20 silage had the lowest pH by high lactate concentration and led to high aerobic stability.
        4,000원
        36.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There has been a steady rate of accident in Coal Thermal Power Plants which have relatively higher chance of mortality. However, neither the systematic view of safety management nor the methodology such as safety factors or system requirements are yet to be studied in detail. Therefore, this study aims to propose a methodology to preemptively deal with safety issues and to secure fact focused responsibility in safety. It consists of two main parts. First, the Safety Measurement Index(SMI) with total 50 factors is proposed by analyzing the key factors that contribute to safety accidents based on failure mode and effect analysis (FMEA) and quality function deployment (QFD). To analyze the safety requirements, index presented by major countries and organizations are discussed. Second, main features of intelligent CCTV are studied to determine their relative importance for the framework of Smart Safety Management System (SSMS). Main features are discussed with four technological steps. Also, QFD was held to analyze to analyze how key technologies deal with Quality Measurement Index(QMI). The research results of this study reveal that scientific approaches could be utilized in integrating CCTV technologies into a smart safety management system in the era of Industry 4.0. Moreover, this reasearch provides an specific approach or methodology for dealing with safety management in Coal Thermal Power Plant.
        4,600원
        37.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        현재 기술이 발전하게 됨에 따라 멀티미디어 콘텐츠 제작에는 많은 비용과 인적자원이 필요하고, 수많은 멀 티미디어 제작 도구 소프트웨어가 필요하게 되었다. 이런 각각의 멀티미디어 제작 소프트웨어들은 배울 내용 이 너무 많은데다가 고품질의 최종결과물을 만들기 위해서 많은 시간이 소요되는 문제점이 있다. 그렇기 때 문에 대학생들이 실무 업계에서 통용될 수 있는 멀티미디어 콘텐츠 제작을 위해서 4년이라는 대학교육 시간 내에서 이것들을 전부 학습하기엔 무리가 있고 여러 가지 제약이 수반될 수밖에 없다. 이러한 문제점들이 대 두된 가운데 게임을 제작하기 위한 게임 엔진이 새로운 대안으로 제시되고 있다. 여러 가지 소프트웨어로 만 들어야 했던 멀티미디어 콘텐츠를 게임 엔진으로 하나로 통합하여 만들 수 있게 되었고, 실시간 렌더링을 할 수 있는 게임 엔진의 특성상 최종 결과물을 만드는 데 기존의 방식보다 비약적인 시간 단축이 가능하기 때 문이다. 본 논문에서는 대학에서 효율적인 교육을 위하여 상용게임 엔진 중 가장 많이 쓰는 Unity 엔진과 Unreal 엔진을 중심으로 각 게임 엔진의 특성과 장·단점을 비교 분석함으로써 위 두 엔진 중 대학교에서 어 떤 것을 선택하여 교육하는 것이 효율적인지에 대한 분석 결과를 제시하고자 한다.
        4,000원
        40.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Backpacks are one of the most widely used accessories in modern society. However, previous studies have shown that carrying a backpack can cause various musculoskeletal problems. Objectives: To investigate the effects of a body-adhesive backpack on craniovertebral angle, sagittal shoulder angle and the muscle fatigue in the upper extremity. Design: Randomized cross-over design. Methods: For this study, 36 healthy university students participated in this study. The experiment was conducted three times using common backpack, and body-adhesive backpack condition. The angles of the cervical spine and shoulder joints of the subjects were calculated without the backpack. Electrodes were placed at upper trapezius, lower trapezius, rectus abdominis and erector spinae to check for muscle fatigue. Subjects carried a backpack and walked on a treadmill for 15 minutes at 4 km/h. The muscle fatigue signal was also measured while walking. After walking, the craniovertebral and sagittal shoulder angles were measured again while subjects carried backpack. Results: As a result of this study, body-adhesive backpack condition showed significant decrease and significant increase in craniovertebral angle and sagittal shoulder angle than common backpack (P<.05). Body-adhesive backpack condition showed significant decrease in upper trapezius, lower trapezius, erector spinae, and rectus abdominis when compared to a common backpack (P<.05). Conclusion: This study suggests that a body-adhesive backpack is more beneficial in correcting body posture than a common backpack.
        4,000원
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