• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.131-137
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• 2024

Aerodynamic noise generated by the surrounding flow of a train traveling at high speed affects both outdoor and indoor noise. This study's goal is to develop a test method to measure and quantitatively evaluate aerodynamic noise through pressure perturbation data on the train surface. To accurately evaluate aerodynamic noise, it is important to separate and evaluate the compressive and incompressible pressure fluctuations mixed in the acquired surface pressure fluctuation data. This is because the noise transmission characteristics of the two pressure fluctuations are different. First, the installation length and interval of the microphone were determined to acquire surface pressure fluctuation data, and wavenumber-frequency analysis was performed to separate incompressible pressure fluctuation and compressible pressure fluctuation to obtain a sound pressure level spectrum. Finally, as a result of comparing the test results measured in the train head and trail, It was confirmed that the pressure fluctuation on the train head surface was greater than that on the tail.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1034-1043
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• 2021

Objective: The purpose of this meta-analysis was to investigate the pooled agreements of the coronary artery calcium (CAC) severities assessed by electrocardiogram (ECG)-gated and non-ECG-gated CT and evaluate the impact of the scan parameters. Materials and Methods: PubMed, EMBASE, and the Cochrane library were systematically searched. A modified Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate the quality of the studies. Meta-analytic methods were utilized to determine the pooled weighted bias, limits of agreement (LOA), and the correlation coefficient of the CAC scores or the weighted kappa for the categorization of the CAC severities detected by the two modalities. The heterogeneity among the studies was also assessed. Subgroup analyses were performed based on factors that could affect the measurement of the CAC score and severity: slice thickness, reconstruction kernel, and radiation dose for non-ECG-gated CT. Results: A total of 4000 patients from 16 studies were included. The pooled bias was 62.60, 95% LOA were -36.19 to 161.40, and the pooled correlation coefficient was 0.94 (95% confidence interval [CI] = 0.89-0.97) for the CAC score. The pooled weighted kappa of the CAC severity was 0.85 (95% CI = 0.79-0.91). Heterogeneity was observed in the studies (I² > 50%, p < 0.1). In the subgroup analysis, the agreement between the CAC categorizations was better when the two CT examinations had reconstructions based on the same slice thickness and kernel. Conclusion: The pooled agreement of the CAC severities assessed by the ECG-gated and non-ECG-gated CT was excellent; however, it was significantly affected by scan parameters, such as slice thickness and the reconstruction kernel.

• Journal of Acupuncture Research
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• v.27 no.4
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• pp.239-245
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• 2010

Objectives : The aim of this study is to evaluate the effect of cervical Hyeopcheok(Jiaji) point for neck pain. Methods : The twenty-nine patients who feel neck pain, are chosen from chart review, received acupuncture treatment on cervical Hyeopcheok(Jiaji) point. The evaulation of progress was checked by NDI(neck disability index), and VAS(visual analog scale). Data were analyzed by Friedman two way analysis of variance and Wilcoxon matched pairs signed rank test. Results : NDI value(mean${\pm}$SD) was $17.76{\pm}8.26$(n=29) at the first visit, $13.41{\pm}8.04$(n=29) at 3days after treatment, $10.85{\pm}8.46$(n=26) at 5days, $11.00{\pm}7.80$(n=13) at 9days, $7.22{\pm}4.76$(n=9) at 15days, $3.86{\pm}4.06$(n=7) at 20days, and $3.33{\pm}3.78$(n=6) at 30days. VAS value(mean${\pm}$SD) was $4.07{\pm}1.33$(n=29) at the first visit, $12.97{\pm}1.05$(n=29) at 3days after treatment, $2.15{\pm}1.12$(n=26) at 5days, $2.15{\pm}0.99$(n=13) at 9days, $1.56{\pm}0.73$(n=9) at 15days, $1.29{\pm}0.49$(n=7) at 20days, and $0.83{\pm}0.41$(n=6) at 30days. The value of NDI and VAS gradually decreased. Repeated measurement results(the difference between the first visit and each measurement day) and the difference between before and after the interval(except between 5 and 9days, between 20 and 25days) were statistically significant. Conclusions : This result was shown that treatment of cervical Hyeopcheok(Jiaji) acupuncture point for neck pain can be effective. Further systematic research will be needed.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.17-25
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• 1991

This study was undertaken to find the effect of radiation therapy on the healing ability of surgical wounds and on this basis, to find the proper time interval between the radiation therapy and surgery. Two hundred and fifty-two mice were used and a single dose of 2000 cGy was given in each instances to the hind limb of mice. Incisional wounds were produced after varying intervals in the previously irradiated areas and then they were followed up at regular intervals by the measurement of tensile strength. The wounds which received surgery immediately, 1 or 2 weeks after irradiation revealed marked delay and the wounds which received surgery 12, 16 or 20 weeks after irradiation demonstrated slight delay in wound healing in terms of tensile strength measurement. But the wounds which received irradiation 4 or 8 weeks before surgery did not differ much in the wound healing process from that of the control group. Histopathologic studies of the wounds demonstrated epithelization in most instances as quickly as in the control wounds. The appearance of fibroblasts and collagen fibers has delayed momently and appeared to have close correlation with the tensile strength healing curves.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.439-448
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• 2001

This paper considers the acoustical characteristics of the closing click sounds of the mechanical valves employed in an implantable biventricular assist device (BYAD) and their re1evance to the Physical states of the valved. Bj rk Shiley Convexo Concave tilting disk valve was chosen for the study and acoustic measurement was made for the BYAD operated in a mock circulatory system as well as implanted in an animal (sheep). In the BYAD operated in the mock circulatory system. three different states of the valve were examined, ie. normal. mechanically damaged. pseudo-thrombus attached. Microphone measurement for the BVAD implanted in the animal was carried out for five days at a regular time interval from one day after implantation. Characteristic spectrum of the sound from the valve was estimated using Multiple Signal Classification (MUSIC) in which the optimal order was determined according to Bayesian Information Criterion (BIC) . It was observed that the mechanical damage of the valve resulted in changes of the structure of the acoustic spectrum. In contrast. the thrombus formed on the valve did not change much the basic structure of the spectrum but brought about altering the spectral Peak frequencies and energies. Maximum spectral Peak (MSP) with the greatest energy was seen at 2 kHz for the normal valve and it was shifted to 3 kHz for the calve attaching the Pseudo-thrombus. Unlike the normal valve, strong spectral Peak appeared around 7 kHz in the sound from the valve mechanically damaged. In the case of the BYAD implanted in the animal. as the thrombus grew, acoustic energy was reduced relatively more in the low frequency components (〈 2 kHz) and the frequencies of the 1st, 2nd and 3rd MSP were increased little. The thrombus formation would result in reduction in both the variability of the 1st, 2nd and 3rd MSP and the value of the BIC optimal order.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1530-1530
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• 2001

The objectives of this study were to develop models to predict quality parameters of Korean bee-honeys by visible and NIR spectroscopic technique. Two kinds of bee-honey fronl acacia and polyflower sources were tested in this study. The honeys were harvested in the spring of 2000 and stored in the storage facility at 20$^{\circ}C$ during experiments. Total of 394 samples of honey were analyzed. Reflectance spectra, moisture contents, ash, invert sugar, sucrose, F/G (fructose/glucose) ratio, HMF (hydroxymethyl furfural), and C12/C13 ratio of honeys were measured. The average values for the tested honeys were 19.9% of moisture contents, 0.12% of ash, 68.4% of invert sugar, 5.7% of sucrose, 1.27 of F/G(fructose/glucose) ratio, 14.4 mg/kg of HMF, and -19.1 of C12/C13 ratio. A spectrophotometer, equipped with a single-beam scanning monochromator (NIR Systems, Model 6500, USA) and a horizontal setup module, was used to collect reflectance data from honey. The reflectance spectra were measured in wavelength ranges of 400∼2,498 nm. with 2 nm of interval. Thirty-two repetitive scans were averaged, transformed to log(1/Reflectance), and then were stored in a microcomputer file, forming one spectrum per measurement. A sample cell and reflectance plate were made to hold honey samples constantly. Spectra of honey samples were divided into a calibration set and a validation set. The calibration set was used during model development, and the validation set was used to predict quality parameters from unknown spectra. The PLS(Partial Least Square) models were developed to predict the quality parameters of honeys. The first and the second derivatives of raw spectra were also used to develop the models with proper smoothing gap. The MSC (multiplicative scatter correction) and the SNV & Dtr.(standard normal variate and detranding) preprocessing were applied to all spectra to minimize sample-to-sample light scatter differences. The PLS models showed good relationships between predicted and measured quality parameters of honeys in the wavelength range of 1100∼2200 nm. However, the PLS analysis was not good enough to predict HMF of honeys.

• Journal of Korean Physical Therapy Science
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• v.7 no.1
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• pp.377-396
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• 2000

After warming-up exercise for 20 minutes, Isokinetic measurement of trunk strength for flexor and extensor was done by using Cybex 6000 TEF Unit on 91 healthy male white workers from 22years old to 49 years old, and compared each other. 20 repetitions of trunk extension-flexion were done at $120^{\circ}$/sec angular velocity. After resting for 1 minutes, Four repetitions at two different angular velocities($60^{\circ}$/sec, $120^{\circ}$/sec) were done with 30 seconds of resting interval between each angular velocity. The purpose of this study is to obtain the isokinetic normative strength values for trunk extensors and flexors, and is to know the correlation between age, height, weight of subjects and data from isokinetic trunk strength measurement, and is to provide a guideline for exercise program of male white collar workers The collected data were analyzed by ANOVA, Duncan's Multiple Range Test, and Pearson correlation coefficiency in PC-SAS program. The results obtained were as follow; 1. There is significant positive-correlation with the statistic value between weight and peak torque of trunk muscles at two different angular velocities($60^{\circ}$/sec, $120^{\circ}$/sec)(p<01), between height and peak torque of trunk muscles at two different angular velocities($60^{\circ}$/sec, $120^{\circ}$/sec) except peak torque of trunk flexor at $60^{\circ}$/sec(p<01). 2. There is nagitive-correlation between age and peak torque of trunk muscles at two different angular velocities($60^{\circ}$/sec, $120^{\circ}$/sec), there is significant differences with statistic value between age and peak torque of trunk extensor at $120^{\circ}$/sec(p<.01). 3. Mean peak torque and mean peak torque % by body weight of trunk extensor is 1.1 times higher values than trunk flexor at $60^{\circ}$/sec. 4. There is the increase in peak torque angle of trunk flexor with increasing of age, and the decrease in peak torque angle of trunk flexor with increasing of age at two different angular velocities($60^{\circ}$/sec, $120^{\circ}$/sec). there is significant differences with statistic value in peak torque angle of trunk flexor at $120^{\circ}$/sec(p<.01). 5. There is significant decrease in endurance ratio of trunk extensor with increasing of age at $120^{\circ}$/sec(p<.01). In conclusion, peak torque of trunk extensor is 1.1 times higher values than trunk flexor in healthy male white collar workers.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.12-20
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• 2009

Statement of problem: When an implant is fixed, a fixture comes into contact with a tissue fluid. Adhesion of a tissue fluid to a surface of implant is various case by case. Purpose: The ultimate goal of this work is to analyze a correlation between a surface roughness and wettability of implant specimens. A measurement for wettability is performed considering 4 types of specimen implant with surface treatments different from each other to investigate the change of wettability with the elapse of time. Material and methods: Firstly, 20 specimens of titanium were prepared. The specimen were made of a commercial Titanium Grade IV with the diameter of 10 mm and the thickness of 1 mm. According to the method of surface treatment, the specimens were classified into 4 groups of 5 specimens per group. Group A: Machined Surface Group B: Anodized surface Group C: RBM (HA blasting) surface Group D: CMP (calcium methaphosphate) coating surface. Surface roughness of specimen was measured using SV-3000S4 (Mituyoto, Japan). The measurement was based on the standard of JIS1994. Sessile drop method was used to measure the wettability, which measures contact angle between implant disc and saline with the time interval of 5, 10, and 15 seconds. SPSS 11.0 was used to analyze the collected data. In order to analyze the difference of wettability and surface roughness according to implant surface treatment method. The statistical significance was tested with the confidence level of 95%. Pearson's correlation coefficient was used to evaluate the correlation of surface roughness and wettability. Results: The difference of surface roughness was statistically significant in the order of Group C ($1.69{\pm}0.26$), Group D ($1.58{\pm}0.16$), Group B ($0.78{\pm}0.14$) Group A ($0.18{\pm}0.05$). The wettability has also a statistically significant difference, which was in the order of group B ($17.70{\pm}2.66$), Group C ($27.86{\pm}4.52$), Group D ($66.28{\pm}3.70$) Group A ($70.52{\pm}8.00$). There was no difference in wettability with the passage of time. Conclusions: 1. The surface roughness was high in the order of RBM, CMP, Anodized, Machined group (P<.05). 2. The wettability was high in the order of Anodized, RBM, CMP, Machined group (P<.05). 3. There was no statistical significance in the correlation of surface roughness and wettability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.376-383
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• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each subsystem, this partition will cause unwanted effects. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is used for the way of maintaining radiated emission, still specific user's guide doesn't give sufficient principle. In a view point of EMI, design principle of multi-CB using method will be analyzed by measurement. And design principle of noise mitigation will be provided. Generally interval of multi-CB is ${\lambda}/20$ ferrite bead. In this study, When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of EMI.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.366-375
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• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each sub system, this partition will cause unwanted effects. In a circuital point of view, RCP partition has a bad influence upon signal integrity. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is usecl for the way of maintaining signal integrity, still specific user's guide doesn't give sufficient principle. In a view point of signal integrity, design principle of multi-CB using method will be analyzed by measurement and simulation. And design principle of noise mitigation will be provided. Generally interval of CB is ${\lambda}/20$ ferrite bead. In this study. When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement and simulation. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of signal integrity.