• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.2059-2064
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• 2004

Texture analysis is an important role for automatic visual insfection. This paper presents an application of wavelet extension and Gray level co-occurrence matrix (GLCM) for detection of defect encountered in textured images. Texture characteristic in low quality images is not to easy task to perform caused by noise, low frequency and small dimension. In order to solve this problem, we have developed a procedure called wavelet image extension. Wavelet extension procedure is used to determine the frequency bands carrying the most information about the texture by decomposing images into multiple frequency bands and to form an image approximation with higher resolution. Thus, wavelet extension procedure offers the ability to robust feature extraction in images. Then the features are extracted from the co-occurrence matrices computed from the sub-bands which performed by partitioning the texture image into sub-window. In the detection part, Mahalanobis distance classifier is used to decide whether the test image is defective or non defective.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1854-1858
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• 2007

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, which is carried out to obtain basic dynamic characteristics of the fuel assembly, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification cation for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. Finally, to verify the test result to represent the accurate natural characteristics of the structure, the proper correlation analysis between the theoretical and experimental method has to be carried out. In this study, the overall procedure and result of lateral vibration test for the fuel assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

• Computers and Concrete
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• 제5권2호
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• pp.101-116
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• 2008

The microscopic determination of air void characteristics in hardened concrete, defined in EN 480-11 as the linear-traverse method, is an extremely time-consuming and tedious task. Over past decades, several researchers have proposed relatively expensive mechanical automated systems which could replace the human operator in this procedure. Recently, the appearance of new high-resolution flatbed scanners has made it possible for the procedure to be automated in a fully-computerized and thus cost-effective way. The results of our work indicate the high sensitivity of such image analysis automated systems firstly to the quality of sample surface preparation, secondly to the selection of the air void threshold value, and finally to the selection of the probe system. However, it can be concluded that in case of careful validation and the use of the approach which is proposed in the paper, such automated systems can give very good estimate of the air void system parameters, defined in EN 480-11. The amount of time saved by using such a procedure is immense, and there is also the possibility of using alternative stereological methods to assess other, perhaps also important, characteristics of air void system in hardened concrete.

• Journal of Power Electronics
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• 제5권3호
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• pp.198-205
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• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• Coupled systems mechanics
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• 제11권1호
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• pp.33-41
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• 2022

Quite often we have a lot of measurement data and would like to find some relation between them. One common task is to see whether some measured data or a curve of known shape fit into the cumulative measured data. The problem can be visualized since data could generally be presented as curves or planes in Cartesian coordinates where each curve could be represented as a vector. In most cases we have measured the cumulative 'curve', we know shapes of other 'curves' and would like to determine unknown coefficients that multiply the known shapes in order to match the measured cumulative 'curve'. This problem could be presented in more complex variants, e.g., a constant could be added, some missing (unknown) data vector could be added to the measured summary vector, and instead of constant factors we could have polynomials, etc. All of them could be solved with slightly extended version of the procedure presented in the sequel. Solution procedure could be devised by reformulating the problem as a measurement problem and applying the generalized inverse of the measurement matrix. Measurement problem often has some errors involved in the measurement data but the least squares method that is comprised in the formulation quite successfully addresses the problem. Numerical examples illustrate the solution procedure.

• 한국과학교육학회지
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• 제25권3호
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• pp.321-326
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• 2005

본 연구는 군집 분석을 통해 학생들의 복합적인 성취 목적 양식을 확인하고, 이것이 학습 전략(심층적/피상적)과 과학 성취도에 미치는 영향을 조사하였다. 성취 목적(과제 지향/수행 지향/수행 회피)에 대해 군집 분석을 실시한 결과, '과제 지향 목적이 높은 집단(군집 1)'. '과제 지향 목적과 수행 지향 목적이 모두 높은 집단(군집 2)', '과제 지향 목적과 수행 지향 목적이 모두 낮은 집단(군집 3)'으로 구분되었다. 일원 변량 분석 결과, 심층적 학습 전략에서 군집 2의 평균이 군집 1과 군집 3보다 유의미하게 높았으며, 과학 성취도에서 군집 1과 군집 2의 평균이 군집 3보다 유의미하게 높은 것으로 나타났다. 피상적 학습 전략에서는 군집 3의 평균이 군집 1과 군집 2보다 유의미하게 높았다. 본 연구 결과에 대한 교육적 함의를 논의하였다.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.111-111
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• 2001

목적： To evaluate the feasibility of the event-related functional MR study using power grip studying the hand motor system 대상 및 방법： Event-related functional MRI was performed on a 1.5T MR unit in seven norm volunteers (man=7, right-handedness=2, left-handedness=5, mean age： 25 years). A single-shot GRE-EPI sequence (TR/TE/flip angle： 1000ms/40ms/90, FOV = 240 mm matrix= 64$\times$64, slice thickness/gap = 5mm/0mm, 7 true axial slices) was used for functiona MR images. A flow-sensitive conventional gradient echo sequence (TR/TE/flip angl 50ms/4ms/60) was used for high-resolution anatomical images. To minimize the gross hea motion, neck-holders (MJ-200, USA) were used. A series of MR images were obtained in axial planes covering motor areas. To exclude motion-corrupted images, all MR images wer surveyed in a movie procedure and evaluated using the estimation of center of mass of ima signal intensities. Power grip task consisted of the powerful grip of all right fingers and hand movement ta used very fast right finger tapping at a speed of 3 per 1 second. All tasks were visual-guid by LCD projector (SHARP, Japan). Two tasks consisted of 134 phases including 7 activatio and 8 rest periods. Active stimulations were performed during 2 seconds and rest period were 15 seconds and total scan time per one task was 2 min 14 sec. Statistical maps we obtained using cross-correlation method. Reference vector was time-shifted by 4 seconds an Gaussian convolution with a FWHM of 4 seconds was applied to it. The threshold in p val for the activation sites was set to be 0.001. All mapping procedures were peformed usin homemade program an IDL (Research Systems Inc., USA) platform. We evaluated the activation patterns of the motor system of power grip compared to hand movement in t event-related functional MRI.

• 한국의료질향상학회지
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• 제9권2호
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• pp.148-163
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• 2002

Background : The personnel of emergency department have been under tremendous pressure to manage unexpected emergency situations and excited patients. And interpersonal conflict has existed always, because emergency department was consisted of various personnel of their own specialty. The patient's satisfaction has to come from the personnel's satisfaction. The purpose of this study was to evaluate emergency department personnel's job satisfaction and its related factors and to improve quality of emergency medical service Methods : A self-administered questionnaire survey to the emergency department personnel was conducted between September 1 and October 31, 2001. The response rate was 90.2%. Using SAS program (Version 6.12), the collected data was analyzed by frequency, ANOVA, multiple comparison, Pearson correlation procedure, and stepwise multiple regression analysis. Result : The analysis of related factors of job satisfaction showed high score of interpersonal interaction (3.246), professional prestige (3.095), autonomy (2.916), task requirements (2.701), organizational requirements (2.444), and pay (1.953) in order of item mean. Professional prestige (0.498), task requirements (0.464), and organizational requirements (0.408) were highly positive correlated with overall level of job satisfaction. The factors influencing the job satisfaction were professional prestige and task requirements which explaining efficacy were 37.6% and 32.2% respectively. The total explaining efficacy was 33.6%. Conclusion : It was found out that emergency department personnel's job satisfaction can be raised by promoting professional prestige and task requirements. The personnel of emergency department have to be satisfied through their job, and the administration of the hospital has to pay more attention to their employees' job satisfaction and it related factors.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.151-164
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• 2013

A key input for the assessment of Human Error Probabilities (HEPs) with Human Reliability Analysis (HRA) methods is the evaluation of the factors influencing the human performance (often referred to as Performance Shaping Factors, PSFs). In general, the definition of these factors and the supporting guidance are such that their evaluation involves significant subjectivity. This affects the repeatability of HRA results as well as the collection of HRA data for model construction and verification. In this context, the present paper considers the TAsk COMplexity (TACOM) measure, developed by one of the authors to quantify the complexity of procedure-guided tasks (by the operating crew of nuclear power plants in emergency situations), and evaluates its use to represent (objectively and quantitatively) task complexity issues relevant to HRA methods. In particular, TACOM scores are calculated for five Human Failure Events (HFEs) for which empirical evidence on the HEPs (albeit with large uncertainty) and influencing factors are available - from the International HRA Empirical Study. The empirical evaluation has shown promising results. The TACOM score increases as the empirical HEP of the selected HFEs increases. Except for one case, TACOM scores are well distinguished if related to different difficulty categories (e.g., "easy" vs. "somewhat difficult"), while values corresponding to tasks within the same category are very close. Despite some important limitations related to the small number of HFEs investigated and the large uncertainty in their HEPs, this paper presents one of few attempts to empirically study the effect of a performance shaping factor on the human error probability. This type of study is important to enhance the empirical basis of HRA methods, to make sure that 1) the definitions of the PSFs cover the influences important for HRA (i.e., influencing the error probability), and 2) the quantitative relationships among PSFs and error probability are adequately represented.

• 한국전자통신학회논문지
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• 제16권1호
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• pp.89-94
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• 2021

본 논문에서는 학습 과제 수행 시 청각 자극이 뇌에 미치는 영향을 확인하기 위하여 뇌파 계측 실험을 통해 얻은 데이터로 분석한 결과를 제시하였다. 피험자가 수학적 과제를 해결하는 동안, 피험자의 선호도에 따라 구분한 선호 음악 및 비선호 음악을 청각 자극으로 제시하였으며, 수학적 과제는 암기형 및 절차형 과제로 구분하여 뇌파를 측정하였다. 이를 집중력과 관련된 뇌파의 주파수 대역인 세타파, SMR파 및 중간베타파로 나누어 상대 파워 스펙트럼 값을 비교하였다. 본 논문의 결과로는 무음악과 선호 음악 및 무음악과 비선호 음악을 비교한 경우에서 유의한 차이를 나타내는 채널을 관측할 수 있었으며, 공통적으로 전두엽 부위의 채널인 F3 및 F4에서 평균의 차이를 나타냈다. 유의미한 차이를 나타낸 채널들에서도 음악이 없는 경우보다 음악이 제시된 경우의 파워가 더 크게 나타났으며, 선호도에 따라서는 선호 음악이 비선호 음악의 경우보다 두뇌의 활성도가 크게 나타난다는 사실을 실험결과로부터 확인할 수 있었다.