• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.135-140
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• 2017

In this paper, a novel measurement method of radial artery pulse waveform using robotic applanation tonometry (RAT) was present to reduce the errors by the pressing direction of the vessel. The RAT consisted of an array of pressure sensors and 2-axis tilt sensor, which was attached to the universal joint with a linear spring and five-DOF robotic manipulator with a one-axis force sensor. Using the RAT mechanism, the pulse sensor could be manipulated to perpendicularly pressurize the radial artery. A pilot experimental result showed that the proposed mechanism could find the optimal pressurization angles of the pulse sensor within ${\pm}3^{\circ}$standard deviations. Coefficient values of variation of maximum pulse peaks extracted from the pulse waveforms were 4.692, 6.994, and 11.039 % for three channels with the highest magnitudes. It is expected that the proposed method can be helpful to develop more precise tonometry system measuring the pulse waveform on the radial artery.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1279-1286
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• 1999

In conventional GPS/DR integration schemes, the GPS position (or pseudo-range) information is used in calibrating DR sensors. In those schemes, however, an inaccurate calibration may degrade the position accuracy when the GPS measurement is not available. This paper presents a new integration scheme where the GPS velocity information is used in calibrating DR sensors. Also proposed is a new error model of DR sensors for calibrating the bias error and the tilt error in dynamic environments. The proposed model makes it possible that the errors of both the DR sensor parameters and the velocity are calibrated using the GPS carrier-based velocity(or the pseudo-range rate) measurement while the DR position error is calibrated using the GPS position measurement. Since the DR sensors are calibrated accurately, the positioning accuracy is drastically improved when the GPS measurements are unavailable.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.466-469
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• 2002

The vibration measurement of the AC motor, the most typically used vibration source, is essential to evaluate the causes of unexpected excessive vibration in many mechanical systems. The motor contributes to excite the resonance of the mechanical systems, and in turn tilt amplified vibration of the mechanical parts cause the motor to vibrate severely. Without the vibration evaluation on the motor itself, it is time consuming to solve the vibration problems. This paper deals the vibration measurement method for the AC motor itself.

• Tunnel and Underground Space
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• v.15 no.1 s.54
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• pp.1-8
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• 2005

Measurement of convergence was/is carried out manually throughout the world for tunnels under construction. However, manual method has certain limitations in terms of applicability for the tunnels in operation. This paper describes state of the art of convergence monitoring systems which are available for measuring displacement of existing tunnels. These technologies are analyzed as follows: 1 The Sofo system using the fiber optic sensors has been applied to the stress measurement of the tunnel lining. It has not yet been used for the monitoring of tunnel convergence because of its cost and reliability 2. A TPMS(Tunnel Profile Monitoring System) using tilt sensors and displacement sensors is used for the convergence monitoring of highway tunnels, subway tunnels and underground ducts. 3. A BCS(Bassett Convergence System) using a pair of tilt sensors can be used for the convergence monitoring of tunnels, however the accuracy of the measurement has to be improved because it uses AC input voltage during data acquisition. The system has to be validated before it can be applied to the tunnels in operation. Convergence monitoring systems using TPMS and/or BCS are recommended to be evaluated and improved by a series or tests in tunnels under construction in order to be applied to the main measuring section and the tunnels in operation.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.27-32
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• 2015

This paper describes a distance measurement system with high accuracy that utilizes a stereo-based camera and a pan-tilt unit for automatically maintaining the positional relationship between a vessel and a target on the side of a facility at a close range. The measurement system offers an advantage in that it can measure the distance to a target while tracking it. In order to improve the ability to control the position of a vessel between it and a target while maintaining the distance especially at a close range, the accuracy of the measurement system has to be improved. The accuracy of the distance measured by our system is increased with revisions of the conclusively generated data of distance measurement. We verified the accuracy of our system from an experiment, which generated results that had an accuracy of 30 mm for distances in the range between 2-8 m.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.1
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• pp.88-99
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• 2003

The body changes of the elderly women are the forward tilt of the neck and shoulder point shrinkage of the spinal column, and protrusive abdomen. Unfortunately, few data based on body measurements for elderly women existed and a few studies are limited to the body figure of the elderly women. If these changes are not applied to the manufacturing of the clothing, almost of the elderly women will be unfitted with their clothing. So to improve the fitting of the elderly women, it is necessary to use the standard size systems for elderly women. This report is the first study to develop the standard tables of body measurements to be used for improving the fit of garments and patterns for women aged 60 and older. This study drew from anthropometric measurements of 337 and photographic measurements of 276 women aged 60 and older. It described the protocol of anthropometric measurement, the comparison between the measured data and the data on which National anthropometric survey of Korea 1997 is based, and the development of body measurement standard tables for elderly women. And we also considered the regional difference of body dimensions in order to develop the national size standards for elderly women. Further study would include the classification of body dimensions and description of each figure type for sizing apparel of women aged 60 and older.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.

• Journal of Korea Water Resources Association
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• v.53 no.1
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• pp.15-27
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• 2020

Streamflow discharge as a fundamental riverine quantity plays a crucial role in water resources management, thereby requiring accurate in-situ measurement. Recent advances in instrumentations for the streamflow discharge measurement has complemented or substituted classical devices and methods. Among various potential methods, surface current meter using microwave has increasingly begun to be applied not only for flood but also normal flow discharge measurement, remotely and safely enabling practitioners to measure flow velocity postulating indirect contact. With minimized field preparedness, this method facilitated and eased flood discharge measurement in the difficult in-situ conditions such as extreme flood in active ways emitting 24.125 GHz microwave without relying on natural lights. In South Korea, a rectangular shaped instrument named with Microwave Water Surface Current Meter (MWSCM) has been developed and commercially released around 2010, in which domestic agencies charging on streamflow observation shed lights on this approach regarding it as a potential substitute. Considering this brand-new device highlighted for efficient flow measurement, however, there has been few noticeable efforts in systematic and comprehensive evaluation of its performance in various measurement and riverine conditions that lead to lack in imminent and widely spreading usages in practices. This study attempted to evaluate the MWSCM in terms of instrumen's monitoring configuration particularly regarding tilt and yaw angle. In the middle of pointing the measurement spot in a given cross-section, the observation campaign inevitably poses accuracy issues related with different tilt and yaw angles of the instrument, which can be a conventionally major source of errors for this type of instrument. Focusing on the perspective of instrument configuration, the instrument was tested in a controlled outdoor river channel located in KICT River Experiment Center with a fixed flow condition of around 1 m/s flow speed with steady flow supply, 6 m of channel width, and less than 1 m of shallow flow depth, where the detailed velocity measurements with SonTek micro-ADV was used for validation. As results, less than 15 degree in tilting angle generated much higher deviation, and higher yawing angle proportionally increased coefficient of variance. Yaw angles affected accuracy in terms of measurement area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.296-305
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• 2005

Acoustic target strength (TS) of 12 commercially important fish species caught in the Korean waters had been investigated and their results were presented. Laboratory measurements of target strength on 12 dominant fish species were carried out at a frequencies of 75 kHz by single beam method under the controlled condition of the water tank with the 241 samples of dead and live fishes. The target strength pattern on individual fish of each species was measured as a function of tilt angle, ranging from $-45^{\circ}$ (head down aspect) to $45^{\circ}$ (head up aspect) in $0.2^{\circ}$ intervals, and the averaged target strength was estimated by assuming the tilt angle distribution as N ($-5.0^{\circ}$, $^15.0{\circ}$). The 75 to fish length relationship for each species was independently derived by a least - squares fitting procedure. Also, a linear regression analysis for all species was performed to reduce the data to a set of empirical equations showing the variation of target strength to fish length and fish species. An empirical model for fish target strength(TS, dB) averaged over the dorsal aspect of 158 fishes of 7 species and which spans the fish length(L, m) to wavelength(${\lambda}$, m) ratio between 6.2 and 21.3 was derived: TS: 27.03 Log(L)-7.7Log(${\kanbda}$)-17.21, ($r^2$=0.59).

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.84-87
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• 2015

For large optical elements which are tested by many sub-apertures, it takes too much time for a sub-aperture stitching algorithm to get the stitching result. To solve this problem, we propose a fast sub-aperture stitching algorithm to quickly compensate for piston, tilt, and defocus errors. Moreover, the new algorithm is easy to understand and program. We use partial derivatives of measurement data to separately solve piston, tilt, and defocus errors. First, we show that the new algorithm has a lower time complexity than the currently used algorithm. Although simulation results indicate that the accuracy of the new algorithm is lower than the current algorithm in all 20 simulations, our experimental results validate the algorithm and show it is sufficiently accurate for general use.