• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.310-312
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• 2004

The aim of this study was to analyze the characteristics of knee joint sound in frequency domain and classify the knee joint diseases. The spectral analysis of knee joint sounds was performed using LPC(Linear Predictive Coding) and Wigner-Ville distribution. Ten normal subjects and 5 patients with meniscal tearing were enrolled. Each subject was seated on a chair and underwent active knee flexion and extension for 60 seconds. Sampling frequency was 10kHz and electronic stethoscope and electro-goniometer were applied during the knee motion for data collection. The spectral analysis showed 3 peaks in both groups and the difference energy distribution in time-frequency domain. These results suggest that the diagnosis of knee joint pathology using the auscultation could be easier and more correct.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.479-483
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• 2004

A new calculation method of expected overtopping probability of rubble mound breakwater considering real tide occurrence has been proposed. A calculation method of expected overtopping probability of rubble mound breakwater was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself, It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.22 no.1
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• pp.71-76
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• 2016

Background: The objective of this research is to provide base line data on Korea Baseball rehabilitation treatment by presenting the distribution of upper extremity surgeries according the surgical sites of Korean professional baseball players. Methods: The targets of this research are 561 players from nine Korean baseball clubs. The number of players that have undergone surgery was investigated. In other words, the frequency of shoulder joint surgeries, elbow joint surgeries, and wrist and hand surgeries per each baseball club was investigated. Results: The number of the players who have had surgeries was 151, but among the players, there were some who have had repeated surgeries for which the total number of surgery experience was 162. The result showed that elbow joint surgeries were the most frequently enacted, followed by shoulder joint surgeries, and wrist and hand surgeries. From the nine clubs, Samsung was the club with the highest frequency of surgeries. Conclusions: This research shows that Korean professional baseball players need special training centers with systematic rehabilitation programs. Another conclusion suggests that urgent need for rehabilitation program of upper arm which particularly focused on elbow joint is existing. On the basis of this research, we expect more studies on the specific rehabilitation programs which is categorized by injury areas.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.259-271
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• 2020

In Korea, snow damage has happened in the region with little snowfalls in history. Also, accidental damage was caused by heavy snow leads and the public interest on heavy snow has been increased. Therefore, policy about the Natural Disaster Reduction Comprehensive Plan has been changed to include the mitigation measures of snow damage. However, since heavy snow damage was not frequent, studies on snowfall have not been conducted on different points. The characteristics of snow data commonly are not the same as the rainfall data. Some southern coastal areas in Korea are snowless during the year. Therefore, a joint probability distribution was suggested to analyze the snow data with many 0s in a previous research and fitness from the joint probability distribution was higher than the conventional methods. In this study, snow frequency analysis was implemented using the joint probability distribution and compared to the design codes. The results were compared to the design codes. The results of this study can be used as the basic data to develop a procedure for the snow frequency analysis in the future.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.116-122
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• 2012

A short-term atmospheric dispersion factor (${\chi}/Q$) is an essential element for radiological dose assessment following a hypothetical accidental releases of light-water nuclear power plants. The U. S. NRC developed PAVAN program to comply with the U. S. NRC's Regulatory Guide 1.145. Meteorological data is an essential element for atmospheric dispersion, and PAVAN uses a joint frequency distribution data, which represents the occurrence probability of wind speed and wind direction for atmospheric stability. Using the meteorological data measured at Kori and Wolsung sites for the last 5 years (from 2006 to 2010), a variety of joint frequency distribution data were prepared to evaluate ${\chi}/Q$ values with different wind speed classifications (U. S. NRC's recommendation and even distribution of occurrence probability) and periods of meteorological data to be analyzed (1 year, 2 year, 3 year, 4 year, 5 year). As a result, it was found that the influence of the wind speed classification on ${\chi}/Q$ values is little, while the influence of the periods of meteorological data to be analyzed is relatively significant, representing more than 1.5 times in the ratio of maximum to minimum values.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.239-239
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• 2015

This study presents a bivariate extension of the goodness-of-fit measure for regional frequency distributions developed by Hosking and Wallis [1993] for use with the method of L-moments. Utilising the approximate joint normal distribution of the regional L-skewness and L-kurtosis, a graphical representation of the confidence region on the L-moment diagram can be constructed as an ellipsoid. Candidate distributions can then be accepted where the corresponding the oretical relationship between the L-skewness and L-kurtosis intersects the confidence region, and the chosen distribution would be the one that minimises the Mahalanobis distance measure. Based on a set of Monte Carlo simulations it is demonstrated that the new bivariate measure generally selects the true population distribution more frequently than the original method. An R-code implementation of the method is available for download free-of-charge from the GitHub code depository and will be demonstrated on a case study of annual maximum series of peak flow data from a homogeneous region in Italy.

• Journal of Oral Medicine and Pain
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• v.23 no.2
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• pp.127-141
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• 1998

This study was performed to investigate the clinical features of internal derangement of temporomandibular joint. For this study, 117 patients with temporomandibular disorders and 81 dental students without any signs and symptoms of temporomandibular disorders were selected as the patients group and as the control group, respectively. Preferred chewing side, Angle's classification, lateral guidance pattern, maximal mouth opening range, and affected side were recorded clinically. Head and shouldeer posture was measured in a groundplate on which square diagram of five centimeters each had been drawn, and cephalograph was also taken for measurement of head and neck posture. Sonopak of Biopak system (Bioresearch inc., USA) was used to record joint vibration for evaluation of internal healthy status of temporomandibular joint. The data collected were analyzed by SAS statistical program. The results of this study were as follows : 1. Frequency of left side chewing subjects was higher in patients than in control group, but there was no difference in distribution of subjects by Angle's classification. Other types was prvalent in patients whereas group function was more in control group for lateral guidance pattern. 2. As to lateral guidance pattern by clinical diagnosis, patients with internal derangement and/or degenerative joint disease showed higher frequency was consistent with the result by Sonopak impression. 3. There was no difference for shoulder height between the two groups, however, tilting of head and backward extension of cervical spine was more frequent in control group. 4. Acromion was positioned more anteriorly in patients with internal derangement and/or degenerative joint disease than in control group and angle between eye and tragus was larger in patients. Patients with degenerative joint disease showed more flexed head posture than control group did in cephalometric profile. 5. Maximal mouth opening range in patients with internal derangement was the least in all subgroups in patients classified by Sonopak impression.

• Smart Structures and Systems
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• v.17 no.1
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• pp.135-147
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• 2016

This paper describes a smart structural system, which uses smart materials for real-time monitoring and active control of bolted-joints in steel structures. The goal of this research is to reduce the possibility of failure and the cost of maintenance of steel structures such as bridges, electricity pylons, steel lattice towers and so on. The concept of the smart structural system combines impedance based health monitoring techniques with a shape memory alloy (SMA) washer to restore the tension of the loosened bolt. The impedance-based structural health monitoring (SHM) techniques were used to detect loosened bolts in bolted-joints. By comparing electrical impedance signatures measured from a potentially damage structure with baseline data obtained from the pristine structure, the bolt loosening damage could be detected. An outlier analysis, using generalized extreme value (GEV) distribution, providing optimal decision boundaries, has been carried out for more systematic damage detection. Once the loosening damage was detected in the bolted joint, the external heater, which was bonded to the SMA washer, actuated the washer. Then, the heated SMA washer expanded axially and adjusted the bolt tension to restore the lost torque. Additionally, temperature variation due to the heater was compensated by applying the effective frequency shift (EFS) algorithm to improve the performance of the diagnostic results. An experimental study was conducted by integrating the piezoelectric material based structural health monitoring and the SMA-based active control function on a bolted joint, after which the performance of the smart 'self-monitoring and self-healing bolted joint system' was demonstrated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.197-205
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• 2008

In order to estimate mean wind speed in the Gwangyang-Myodo Region, the probability distribution model of extreme values has been used in the statistical analysis of joint distribution probability of daily maximum wind speed and corresponding direction in this paper. For this purpose frequency of daily maximum records at respective stations is inquired into and sample of largest yearly wind speed of sixteen compass direction and non-direction is extracted from daily data of maximum wind speed and appropriate direction of the meteorological observing stations nearby the bridge construction site. These extreme speed records are applied to Gumbel and Weibull distribution model and parameters are estimated through method of moment and method of least squares etc. And also, distribution and parameters are inquired into whether it is fitted through the probability plot correlation coefficient examination. From fitted parameters the largest yearly wind speed of sixteen compass direction and non-direction is extrapolated taking into account factors regarding sample size of data and distance from the bridge construction site according to the appropriate stations.

• Tunnel and Underground Space
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• v.4 no.3
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• pp.274-286
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• 1994

Direct shear tests were on ducted in a laboratory setting in order to investigate the shear strength and deformation behavior of rock joints. Also, the characteristics of acoustic emissions (AE) during shearing of rock joints were studied. The artificial rock joints were created by splitting the intact blocks of Hwangdeung granites and Iksan marbles. Joint roughness profiles were measured by a profile gage and then digitized by Image analyzer. Roughness profile indices(Rp) of the joints were calculated with these digitized data. Peak shear strength, residual shear strength, shear stiffness and maximum acoustic emission(AE) rate were investigated with joint roughness. The peak shear strenght, the residual shear strength and the shear stiffness were increased as roughness popfile index or normal stress increased in the shear tests of granites. In the tests of marble samples, the shear deformation characteristics were not directly affected by joint roughness. As the result of two directional shear tests, the shear characteristics were varied with shear direction. AE count rates were measured during the shear deformation and the AE signals in several stages of the deformation were analyzed in a frequency domain. The AE rate peaks coincided with the stress drops during the shear deformation of joint. The dominant frequencies of the AE signals were in the vicinity of 100 kHz fo rgranite sample and 900 kHz for marble samples. The distribution of amplitude was dispersed with increasing normal stress.