• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.415-416
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• 2007

• 한국소음진동공학회논문집
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• 제25권9호
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• pp.637-643
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• 2015

In recent years, pattern recognition methods have been widely used by many researchers for fault diagnoses of mechanical systems. The soundness of a mechanical system can be checked by analyzing the variation of the system vibration characteristic along with a pattern recognition method. Recently, the hidden Markov model has been widely used as a pattern recognition method in various fields. In this paper, the hidden Markov model is employed for the fault diagnosis of the mass unbalance of a rotating system. Mass unbalance is one of the critical faults in the rotating system. A procedure to identity the location and size of the mass unbalance is proposed and the accuracy of the procedure is validated through experiment.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.282-287
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• 2008

Identification of steady-state is the first step in developing a fault detection and diagnosis (FDD) system. In a complete FDD system, the steady-state detector will be included as a module in a self-learning algorithm which enables the working system's reference model to "tune" itself to its particular installation. In this study, a steady-state detector of a residential air conditioner based on moving windows was designed. Seven representing measurements were selected as key features for steady-state detection. The optimized moving window size and the feature thresholds was suggested through startup transient test and no-fault steady-state test. Performance of the steady-state detector was verified during indoor load change test. From the research, the general methodology to design a moving window steady-state detector was provided for vapor compression applications.

• 대한한방부인과학회지
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• 제30권4호
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• pp.77-88
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• 2017

Objectives: The purpose of this study is to analyze the characteristics of the pulse energy in women with PCOS (Polycystic ovary syndrome) compared with women who have a regular menstrual cycle. Methods: We analyzed the values of pulse energy on 20 patients with PCOS as an experimental group and 40 patients with regular menstrual cycle as a control group. Control group was divided into 20 women with follicular phase and 20 women with luteal phase respectively. Statistical analysis was performed using SPSS/Win 18.0, one way ANOVA and Tukey HSD. Results: The results were as follows. 1. The mean pulse energy of the Right Chon was significantly increased compared with those of the Left Kwan and the Right Kwan among PCOS group. 2. There were no statistically significant pulse energy among control groups. Conclusions: The pulse energy of Lung is bigger than that of Spleen and Liver in PCOS patients compared with women who have a regular menstrual cycle.

• 대한기계학회논문집A
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• 제32권7호
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• pp.583-589
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• 2008

For the purpose of monitoring by ultrasonic test of the ball bearing conditions in rotating machinery, a system for their diagnosis was developed. ultrasonic technique is used to detect abnormal conditions in the bearing system. And various data such as frequency spectrum, energy and amplitude of ultrasonic signals, and ultrasonic parameters were acquired during experiments with the simulated ball bearing system. Based on the above results and practical application for power plant, algorithms and judgement criteria for diagnosis system was established. Bearing diagnosis system is composed of four parts as follows : sensing part for ultrasonic sensor and preamplifier, signal processing part for measuring frequency spectrum, energy and amplitude, interface part for connecting ultrasonic signal to PC using A/D converter, graphic display and software part for display of bearing condition and for managing of diagnosis program.

• 디지털융복합연구
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• 제9권2호
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• pp.141-152
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• 2011

오늘날 데이터센터는 비즈니스에서 핵심영역으로 인식되고 있으며, 이들에 대한 많은 서비스 요구는 보다 많은 에너지 소비를 낳고 있다. 따라서 데이터센터의 높은 수준의 에너지 효율성은 구축, 운영, 폐기 등 그들의 생명주기에 있어서 핵심이슈로 등장하였다. 본 연구에서는 이러한 생명기상에서 데이터센터의 그린화 수준을 진단할 수 있도록 성숙도모델에 기초한 그린데이터센터 수준진단모델을 제시한다. 본 연구에서 제시한 수준진단 모델은 엑션추어 GMM, DCEEF 등 기존 에너지평가모델 및 그린데이터센터 성숙도평가 모델을 참조하였으며, 최종적으로 건축, 공조, 전기, IT, 조직 등 데이터센터의 5개 핵심영역에 대한 진단지표를 제안하였다.

• Journal of Welding and Joining
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• 제21권6호
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• pp.33-39
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• 2003

Wavelet transform analysis results show a spectrum energy distribution of CWT along scale factors distinguish the partial, full and over penetration in a electron beam welding by analyzing the curve of spectrum energy at small scale, middle and large scale range, respectively. Two types of signals collected by Ion collector and x-ray sensors and analyzed. The acquired signals from sensors are very complicated since these signals are very closely related the dynamics of keyhole which interact the very high density energy with materials during welding. The results show the wavelet transform is more effective to diagnosis than Fourier Transform, further for the general welding defects which are not a periodic based, but a transient, non-stationary and time-varying phenomena.

• International Journal of Safety
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• 제9권2호
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• pp.11-15
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• 2010

Infrastructures in Japan constructed mostly in high economic growth period become elder & elder, and the troubles & accidents caused by the aging increase. Though investment for the renewal is necessary, the shortage of public fund delays the action. Besides, we expect the decrease of the population that means the decrease of the engineers who take care of social infrastructures. Thus, it is necessary for us to develop Advanced Management system of social Infrastructures (AMI) to realize the efficient and economical operation. Our concept of AMI consists of using ICT, PI (Public Involvement) and establishment of O&M diagnosis system. We expect AMI will support to realize the appropriate repairing, preventive maintenance based on the actual performance, accidents & dangerous experience and education & training of the workers. In this paper, development of AMI for the waste disposal facility as a first example of infrastructures will be shown.

• Korean Journal of Radiology
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• 제22권9호
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• pp.1555-1568
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• 2021

Pulmonary embolism (PE) is a potentially fatal disease if the diagnosis or treatment is delayed. Currently, multidetector computed tomography (MDCT) is considered the standard imaging method for diagnosing PE. Dual-energy CT (DECT) has the advantages of MDCT and can provide functional information for patients with PE. The aim of this review is to present the potential clinical applications of DECT in PE, focusing on the diagnosis and risk stratification of PE.

• The Journal of the Acoustical Society of Korea
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• 제15권1E호
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• pp.5-19
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• 1996

This paper proposes a loose part monitoring system (LPMS) design with a signal processing method based on fuzzy logic. Considering fuzzy characteristics of metallic impact waveform due to not only interferences from various types of noises in an operating nuclear power plant but also complex wave propagation paths within a monitored mechanical structure, the proposed LPMS design incorporates the comprehensive relation among impact signal features in the fuzzy rule bases for the purposes of alarm discrimination and impact diagnosis improvement. The impact signal features for the fuzzy rule bases include the rising time, the falling time, and the peak voltage values of the impact signal envelopes. Fuzzy inference results based on the fuzzy membership values of these impact signal features determine the confidence level data for each signal feature. The total integrated confidence level data is used for alarm discrimination and impact diagnosis purposes. Through the perpormance test of the proposed LPMS with mock-up structures and instrumentation facility, test results show that the system is effective in diagnosis of the loose part impact event(i.e., the evaluation of possible impacted area and degree of impact magnitude) as well as in suppressing false alarm generation.