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        검색결과 13

        1.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As mechatronic systems have various, complex functions and require high performance, automatic fault detection is necessary for secure operation in manufacturing processes. For conducting automatic and real-time fault detection in modern mechatronic systems, multiple sensor signals are collected by internet of things technologies. Since traditional statistical control charts or machine learning approaches show significant results with unified and solid density models under normal operating states but they have limitations with scattered signal models under normal states, many pattern extraction and matching approaches have been paid attention. Signal discretization-based pattern extraction methods are one of popular signal analyses, which reduce the size of the given datasets as much as possible as well as highlight significant and inherent signal behaviors. Since general pattern extraction methods are usually conducted with a fixed size of time segmentation, they can easily cut off significant behaviors, and consequently the performance of the extracted fault patterns will be reduced. In this regard, adjustable time segmentation is proposed to extract much meaningful fault patterns in multiple sensor signals. By considering inflection points of signals, we determine the optimal cut-points of time segments in each sensor signal. In addition, to clarify the inflection points, we apply Savitzky-golay filter to the original datasets. To validate and verify the performance of the proposed segmentation, the dataset collected from an aircraft engine (provided by NASA prognostics center) is used to fault pattern extraction. As a result, the proposed adjustable time segmentation shows better performance in fault pattern extraction.
        4,300원
        2.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        머신러닝 기법의 발달과 함께 기계에서 발생하는 다양한 종류(진동, 온도, 유량 등)의 데이터를 활용하여 기계의 상태를 진단하고 이상 탐지 및 비정상 분류 연구도 활발히 진행되고 있다. 특히 진동 데이터를 활용한 회전 기계의 상태 진단은 전통적인 기계 상태 모니터링 분야로 오랜 기간 동안 연구가 진행되었고, 연구 방법 또한 매우 다양하다. 본 연구에서는 가정용 에어컨에 사용되는 로터리 압축기에 가속도계를 직접 설치하여 진동 데이터를 수집하는 실험을 진행하였다. 데이터 부족 문제를 해결하기 위해 데이터 분할을 수행하였으며, 시간 영역에서의 진동 데이터로부터 통계적, 물리적 특징들을 추출한 후, Chi-square 검증을 통해 고장 분류 모델의 주요 특징을 추출하였다. SVM(Support Vector Machine) 모델은 압축기의 정상 혹은 이상 유무를 분류하기 위해 개발되었으며, 파라미터 최적화를 통해 분류 정확도를 개선하였다.
        4,000원
        4.
        2016.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effect of roasting intensity and extraction time of coffee bean on the antioxidant activity of roasted ground coffee extract was investigated. Coffee was roasted at 185oC using a rotating fluidized bed roaster for 5.17 (medium roasting) and 6.00 (dark roasting) min, respectively. Both roasted coffees were extracted in 90oC hot water according to the increased extraction time. Until 20 min, an increase in extraction time significantly increased soluble solute, caffeine, brown color, and phenolic compound. The soluble solid and caffeine contents showed no significant difference among medium- and dark-roasted coffee extracts. The brown color intensity and free radical scavenging activity of dark-roasted coffee extract were higher than those of medium-roasted coffee. On the contrary, the total phenolic content of dark-roasted coffee extract was lower than that of medium-roasted coffee. The free radical scavenging activity of coffee extracts showed a positive correlation with brown color intensity, as well as total phenolic content.
        4,000원
        6.
        2014.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Background/Aims: The ballooning time in endoscopic papillary large balloon dilation (EPLBD) remains controversial. The aim of this study was to evaluate the significance of the ballooning time comparing an immediate balloon deflation method with a conventional ballooning time of > 45 seconds. Methods: Between January 2010 and December 2010, 126 patients with bile duct stones treated with EPLBD and endoscopic sphincterotomy were divided according to the ballooning time: the immediate deflation group (n=56) and the conventional inflation group (ballooning time 45s to < 60s) (n=70). Results: The overall success rate and the success rate of the first attempt of ERCP (endoscopic retrograde cholangio-pancreatography) were 96.4% (54/56) and 80.4% (45/56) in the immediate group and 97.1% (68/70) and 77.1% (54/70) in the conventional inflation group. There were no statistically significant differences in the overall success and the first attempt of ERCP success rate (p=0.99, p=0.66). The frequency of mechanical lithotripsy was 0% in the immediate deflation group and 7.1% in the conventional inflation group (p=0.065). Complications occurred in 3.6% (2/56) patients in the immediate deflation group and 8.6% (4/70) patients in the conventional inflation group (p=0.298). Conclusions: The ballooning time in EPLBD does not affect the outcomes of the treatment for bile duct stones. And the feasibility of the immediate deflation method in EPLBD is acceptable.
        4,000원
        7.
        2016.05 서비스 종료(열람 제한)
        Background : From 2000 years ago, Panax ginseng is identified as precious pharmaceutical plant. Depend on growing environment, the name would be vary. For instance, it is called "mountain cultured ginseng (jangnoesam)" which is artificially grown ginseng, "Cultured ginseng (jaebaesam)" which refer to the ginseng grown in the forest, and lastly "Wild ginseng (sansam)" which inhabits in deep mountain. The main active compounds in the Panax ginseng is called ginsenoside and many researches have been performing in biological field. However, most studies focus on functional ability of ginseng. In this study, to seek the suitable extraction condition and antioxidant activity, cell cultured Panax ginseng was extracted according to different ethanol concentration and extraction time. Methods and Results : To establish the optimal extraction condition, the sample was pulverized into 500 μm and added 10% (v/v), 30% (v/v), 50% (v/v), 70% (v/v) and, 90% (v/v) EtOH. After that, the samples are extracted in different time by ultrasonic bath (Power sonic 520, Hwashin Co., Korea). The extracts was filtered by Whatman No. 2 filtering paper. Eventually, the saponin was separated by n-butanol as the ginsenoside, the combination of terpenoid and sugar. The extraction yield of 90% cell cultured panax ginseng EtOH extract was 7.36±0.33%, which was the lowest extraction yield and simultaneously, 10% EtOH extract showed 1.8 times more yield that of 90% EtOH extract. The saponin extraction yield revealed 10% and 70% EtOH extract showed 1.64±0.06% and 3.13±0.08%, respectively. Conclusion : The suitable extraction yield in cell cultured panax ginseng and saponin were evaluated by different extraction condition such as ethanol concentration and extraction time. As a result, when 10% EtOH was applied as solvent, the yield was doubles of 90% EtOH extract. As ethanol became high concentrations, the extraction yield was gradually increased. Among them, crude saponin, the main active compounds in Panax ginseng was extracted the most by 70% EtOH and that value was 3.13±0.08%.
        8.
        2011.08 KCI 등재 서비스 종료(열람 제한)
        In this study, ginseng flower water extracts were analyzed to set up the ginsenoside content and quality optimization condition. The highest total ginsenoside content among the ginseng flower water extracts was 67.44mg/g which was extracted at 85℃ for 3 hours. In addition, the ginsenoside content decreased according to the increased extraction temperature and time. The highest total content of Rb2 and Re was 37.42mg/g at 75℃ for 6 hours. Total content of Rb2 and Re decreased according to the increased extraction temperature and time. The highest prosapogenin (Rg2 + Rg3 + Rh1) content among the total of ginseng flower water extracts was 18.58mg/g which was extracted at 95℃ for 12 hours. The sweetness, absorbance were increased according to the increased extraction temperature and time. But pH was decreased according to the increased extraction time.
        9.
        2010.12 KCI 등재 서비스 종료(열람 제한)
        본 연구는 홍삼의 가능성 식품개발을 위한 기초 자료로 활용하기 위하여 추출 시간에 따른 홍삼 부위별 ginsenoside의 함량 변화를 비교하였다. 동체, 지근 및 세근의 총 ginsenoside 최고 함량은 동제 21시간, 지근 18시간, 세근 12시간 추출하였을 때 각각 23.04, 65.68 295.92 mg/100 ml이었고, 추출시간이 증가할수록 ginsenoside의 총량은 감소하였다. Ginsenoside Rg1 과 Rb1 의 최고 함량은 동제 21시간, 지근 15시간, 세근 12시간 추출하였을 때 각각 5.76, 28.39, 117.83 mg/100 ml 이었고, Rb2 와 Re의 함량은 동체 21시간, 지근 18시간, 세근 9시간 추출하였을 때 각각 5.76, 28.39, 117.83 mg/100 ml이었다. 홍삼으로부터의 총 ginsenoside의 추출비율은 동체 21.3%, 지근 21.1%, 세근 67.1%이었다.
        10.
        2009.10 KCI 등재 서비스 종료(열람 제한)
        In this study, raw ginseng water extract solutions were analyzed to set up the functional saponin content and quality optimization condition. The highest saponin content among the total raw ginseng water extracts was 74.6 mg/100 ml which was extracted at 75℃ for 24 hours. In addition, the saponin content decreased according to the increased extraction temperature and time. The highest total content of Rb2 and Re was 19.9 mg/100 ml at 75℃ for 12 hours which decreased according to the increased extracted temperature and time. The highest prosapogenin (Rg2 + Rg3 + Rh1) content among the total raw ginseng water extracts was 28.6 mg/100 ml which was extracted at 85℃ for 36 hours. The reducing sugar content, sweetness and turbidity were increased according to the increased extraction temperature and time. But pH were decreased according to the increased extracted time.
        11.
        2008.03 KCI 등재 서비스 종료(열람 제한)
        검정콩 품질평가의 한 기준이 되는 안토시아닌의 함량평가를 위한 분석기술 개발의 일환으로 검정콩 종피 함유 안토시아닌의 최적의 추출용매 및 추출방법을 확립하고, 주요재배 검정콩 종피 함유 안토시아닌의 함량을 정량적으로 평가한 결과를 요약하면 다음과 같다. 1. 검정콩 종피 함유 안토시아닌의 최적 추출용매를 검토한 결과 1% HCl - H2O 로부터 1% HCl - 80% MeOH용액까지 통계적 차이가 인정되지 않았으나, 산술적으로 1% HCl - 60% MeOH 용액으로 추출하였을 때 총 안토시아닌의 함량이 7.72 mg/g으로 가장 높은 양상을 나타내었으나, 추출용매에 메탄을 함량이 높아질수록 안토시아닌 피크의 분리도가 극히 불량한 결과를 나타내므로 종합적 견지에서 볼 때 1% HCl - 20% MeOH를 이용하여 안토시아닌을 추출하는 것이 가장 우수한 것으로 평가되었다. 2. 검정콩 종피 함유 안토시아닌의 최적 추출방법 및 추출시간을 검토한 결과 상온 12시간 추출이 가장 우수한 결과를 나타내었으며, 추출시간이 24시간 이상 지속될 경우 추출시간이 증대됨에 따라 안토시아닌의 함량이 소량 감소되는 양상을 확인할 수 있었다. 3. 국내외 주요 재배 검정콩 품종별 종피 함유 안토시아닌 색소의 함량을 비교한 결과 총 안토시아닌의 함량 범위는 1.58-10.62 mg/g으로 조사되었고, 조사된 품종 중 검정 올콩이 10.62 mg으로 가장 높은 양상을 나타내었으며, 가장 낮은 함량을 나타낸 흑청콩 대비 약 7배 높은 안토시아닌 함량을 나타내었다.
        12.
        2005.06 KCI 등재 서비스 종료(열람 제한)
        A unique technique to extract the phase in time domain is proposed in order to measure the time parameters such as speed and depth by transmitting sound and electric waves. In the signal analysis processing, the phase of pulse signal can be transformed and digitalized with local data in real time without the effect of direct current bias and Nyquist limits. This method is sensitive to base frequency of pulse signal with high spacial resolution and is effective to compare two signals which have different forms. It is expected that the phase analysis technique will be applied to the measurement of the speed and depth accurately by ultrasonic pulse signal in water.
        13.
        2002.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        An attempt was made in this study to investigate the optimum extracting time from meat with bone of goat and the nutritional component of its extract. for the trials, the mixtures of meat with bone and water were adjusted to the ratios of five to four by weight and extracted for 6, 9 and 12 hours at 120 under autoclave. Judging from the content of mineral and amino acid, nonenzymatic browning and yield, the optimum extracting time was 9 hours. The major components of mineral were composed of 47.7mg% potassium, 12.7mg% calcium, 150.0mg% sodium, 105.3mg% phosphorus and 0.5mg% iron, and of amino acids composed of 1,308.0mg% glutamic acid, 1,464.2mg% glycine, 750.2mg% alanine and 828.lmg% proline in extract. The yield of extract was 32.1 percentage by dry basis.