• Journal of the Korean Society of Visualization
• /
• v.3 no.1
• /
• pp.20-25
• /
• 2005

An x-ray PIV (Particle Image Velocimetry) technique was developed fur measuring quantitative information on flows inside opaque conduits and/or opaque-fluid flows. To check the performance of the x-ray PIV technique developed, it was applied to a liquid flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, the refraction-based edge enhancement mechanism was employed with seeding detectable tracer particles. The amassed velocity field data obtained were in a reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to get velocity fields of blood flow and to measure size and velocity of micro-bubbles simultaneously, and to visualize the water refilling process in bamboo leaves. The x-ray PIV was found to be a powerful transmission-type flow imaging technique fur measuring quantitative information of flows inside opaque objects and various opaque-fluid flows.

• The Journal of Korean Physical Therapy
• /
• v.29 no.3
• /
• pp.145-151
• /
• 2017

Purpose: The purpose of this study was to investigate the validity and reliability of the measurement of shoulder joint motions using an inertial measurement unit (IMU). Methods: For this study, 33 participants (32 females and 1 male) were recruited. The subjects were passively positioned with the shoulder placed at specific angles using a goniometer (shoulder flexion $0^{\circ}-170^{\circ}$, abduction $0^{\circ}-170^{\circ}$, external rotation $0^{\circ}-90^{\circ}$, and internal rotation $0^{\circ}-60^{\circ}$ angles). Kinematic data on the shoulder joints were simultaneously obtained using IMU three-dimensional (3D) angular measurement (MyoMotion) and photographic measurement. Test-retest reliability and concurrent validity were examined. Results: The MyoMotion system provided good to very good relative reliability with small standard error of measurement (SEM) and minimal detectable change (MDC) values from all three planes. It also presented acceptable validity, except for some of shoulder flexion, shoulder external rotation, and shoulder abduction. There was a trend for the shoulder joint measurements to be underestimated using the IMU 3D angular measurement system compared to the goniometer and photo methods in all planes. Conclusion: The IMU 3D angular measurement provided a reliable measurement and presented acceptable validity. However, it showed relatively low accuracy in some shoulder positions. Therefore, using the MyoMotion measurement system to assess shoulder joint angles would be recommended only with careful consideration and supervision in all situations.

• Wind and Structures
• /
• v.14 no.3
• /
• pp.253-283
• /
• 2011

This paper presents the field measurement results of wind effects on a super-tall building (CITIC Plaza, 391 m high) located in Guangzhou. The field data such as wind speed, wind direction and acceleration responses were simultaneously and continuously recorded from the tall building by a wind and vibration monitoring system during two typhoons. The typhoon-generated wind characteristics including turbulence intensity, gust factor, peak factor, turbulence integral length scale and power spectral density of fluctuating wind speed were presented and discussed. The dynamic characteristics of the tall building were determined based on the field measurements and compared with those calculated from a 3D finite element model of the building. The measured natural frequencies of the two fundamental sway modes of the building were found to be larger than those calculated. The damping ratios of the building were evaluated by the random decrement technique, which demonstrated amplitude-dependent characteristics. The field measured acceleration responses were compared with wind tunnel test results, which were found to be consistent with the model test data. Finally, the serviceability performance of the super-tall building was assessed based on the field measurement results.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1367-1372
• /
• 2009

A proprietary device is adopted to break out the membrane of cell in the rigid polyurethane foam. As it is known, the membrane of cell is hardly tearing-off thoroughly in a mechanical way due to both its elastic characteristic and micro sized pores. In this study, a novel experimental approach is introduced to burst out all gases inside the cells of the rigid polyurethane foam by abrasively grinding micro-cells completely into fine powder. The biggest advantage of this approach is to be capable of releasing all gases out from the cell even in the micro pores. As clearly reflected from the repeatability, the accuracy of the result is highly improved and high confidence in the data sets as well. For the measurements of not only gas composition but partial pressure for each gas simultaneously as well, a precision gas mass spectrometer is used in-line directly to the abrasive grinding device. To control the starting point of the polyurethane foam, all samples were prepared on site in the laboratory. Manufactured time is one of the most critical factors in characterization of cell gas composition because it is known that one of gas composition, especially, carbon dioxide, is diffused out dramatically in a short period of time as soon as it is foamed.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.4
• /
• pp.195-201
• /
• 2002

We propose a new scheme of high-resolution heterodyne interferometer that employs the two-axial mode He-Ne laser with an inter-mode beat frequency of 600~1000 MHz. An electronic RF-heterodyne circuit lowers the beat frequency down to 5 MHz, so that the phase change of the interferometer output is precisely measured with a displacement resolution of 0.1 nanometer without significant loss of dynamic bandwidth. A thermal control scheme is adopted to stabilize the cavity length with ainus to suppress frequency drifts caused by the phenomena of frequency pulling and polarization anisotropy of the two-axial made laser to a stability level of 2 parts in $10^9$. The two-axial mode HeNe laser yields a high output power of 2.0 mW, which allows us to perform multiple measurements of up to 10 machine axes simultaneously.

• Journal of the Korean Society of Physical Medicine
• /
• v.13 no.1
• /
• pp.99-105
• /
• 2018

PURPOSE: The aim of this study was to evaluate the concurrent validity and clinical usefulness of the universal plastic goniometer to measure the range of motion of the internal and external rotation of the hip joint using the three dimensional motion analysis which can analyze the joints and segment movements in the most objective and quantitative method. METHODS: Clinical and kinematic data were collected from thirty individuals using a universal plastic goniometer and a ten camera motion analysis system. Passive hip rotation range was obtained three trials for left and right hip joints using two measure methods simultaneously. RESULTS: There were significant differences between all matching measures of the two measures of internal and external rotation of the hip joint (p<.05). The relationship between the two tests for all measurements of the internal and external rotation of the hip was statistically significant with correlation coefficient form r=.87 to .96. (p<.01). CONCLUSION: Clinical measurement of the internal and external rotation of the hip using a universal plastic goniometer is effective to assess the hip condition. However, application of universal plastic goniometer requires careful attention in more accurate evaluation and research verification of the internal and external rotation of hip joint.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.21 no.4
• /
• pp.370-379
• /
• 2014

Purpose: The purpose of this study was to identify the time for young adults to reach resting blood pressure after walking as measured by an automatic and a mercury sphygmomanometer. Methods: Participants were 33 nursing students in their 20s. Blood pressure after walking was measured every minute on both arms simultaneously for a total of 6 times after walking for 12 minutes on a treadmill at ratings of perceived exertion (RPE) of 11. Data were analyzed using paired t-test, Bland-Altman plots and repeated measures ANOVA. Results: Systolic blood pressure after walking was the same as measurements corresponding to resting blood pressure after 3 minutes of resting if measured with the automatic sphygmomanometer and 4 minutes of resting if measured with the mercury sphygmomanometer. Conclusions: In order to measure the resting blood pressure for healthy young adults who performed low-density walking for 12 minutes on flat land, the measurement needs to be made after a resting time of at least 3 minutes in the case of an automatic sphygmomanometer and 4 minutes in the case of a mercury sphygmomanometer.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.7
• /
• pp.1298-1303
• /
• 2008

Respiration is induced by muscular contraction of the chest and abdomen, resulting in the abdominal volume change. Thus, continuous measurement of the abdominal dimension enables to monitor breathing activity. Conductive rubber cord has been previously introduced and tested to develop wearable application for respiratory measurements. This study implemented respiratory monitoring system with the conductive rubber cord in the patient's pants in purpose of quantitative estimation of tidal volume. Air mixed with $0{\sim}5%$ $CO_2$ was inhaled and the respiratory air flow rate, abdominal dimension change, and end tidal $CO_2$ concentration were simultaneously measured in steady state. $CO_2$ inhalation significantly increased the tidal volume in normal physiological state with the subject unawared. The tidal volume estimated from the abdominal dimension change linearly correlated with the tidal volume measured by a pneumotachometer with a correlation coefficient of 0.88. Customized calibration for each subject resulted in relative errors less than 10%. Therefore, the tidal volume was accurately estimated by measuring the abdominal dimension change.

• Composites Research
• /
• v.16 no.2
• /
• pp.48-53
• /
• 2003

This paper presents a study on the permittivities of the I-glass fabric/epoxy composite laminates containing carbon black dispersions at microwave frequency. Measurements were performed at the frequency band of 5 GHz∼18 GHz. The results showed that the complex permittivities of the composites depend strongly on the natures and concentrations of the carbon black dispersion. A new scheme is proposed to obtain a mixing law for the estimation of the complex permittivities of the composite laminates as a function of concentration of carbon black. Simultaneously, the complex permittivity of carbon black itself was also calculated by the scheme. The experimental values of the complex permittivities of the composites were compared to those calculated.

• Journal of Korean Society for Atmospheric Environment
• /
• v.15 no.3
• /
• pp.305-315
• /
• 1999

The annular denuder system(ADS) was used to determine characteristics of acidic air pollutants and $PM_{2.5}$ species in Seoul-metropolitan areas. All measurements were done simultaneously in downtown(Kwanghwamun, Mullae, Chamshil, Ssangmun dongs) and outskirts(Puch n, Kuri cities) during four seasons. The samples were analyzed using ion chromatography for gas-phase matters(HCl, $HNO_2$, $HNO_3$ and $SO^2$) and particulate phase matters($Cl^-$, $NO^{2-}$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^-$ and $Ca^{2+}$) and was measured fine particles($PM_{2.5}$). The seasonal mean concentrations of HCl, HNO2, HNO3 and SO2 in downtown and outskirt areas were very similar. All chemical species monitored from this study showed seasonal variations. Nitric acid(HNO3) and Nitrous acid(HNO2) were showed higher concentrations during the summer. $PM_{2.5}$, $SO_4^{2-}$, $NH_4^-$, $NO_3^-$ and $Cl^-$ in the particulate phase matters were higher levels during the winter months. The concentrations of these components were 54.8, 3.82, 2.49, 1.80 and 1.02$\mu\textrm{g}$/㎥, respectively.