• Smart Structures and Systems
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• v.6 no.9
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• pp.1007-1023
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• 2010

This paper describes the development and evaluation of an innovative TDR distributed moisture sensor. This sensor features advantages of being responsive to the spatial variations of the soil moisture content. The geometry design of the sensor makes it rugged for field installation. Good linear calibration is obtained between the sensor measured dielectric constant and soil physical properties. Simulations by the finite element method (FEM) are conducted to assist the design of this sensor and to determine the effective sampling range. Compared with conventional types of moisture sensor, which only makes point measurement, this sensor possesses distributed moisture sensing capability. This new sensor is not only easy to install, but also measures moisture distribution with much lower cost. This new sensor holds promise to significantly improve the current field instruments. It will be a useful tool to help study the influence of a variety of moisture-related phenomena on infrastructure performance.

• Journal of the Korean Geophysical Society
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• v.8 no.1
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• pp.7-14
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• 2005

Early detection in real-time response of slope movements ensures tremendous saving of lives and repair costs from catastrophic disaster. Therefore, it is essential to constantly monitor the performance and integrity of slope-stabilizing structures such as Rock bolt, Nail and Pile during or after installation. We developed a novel monitoring system using Fiber Bragg Grating (FBG) sensor. It's advantages are highly sensitivity, small dimension and electro-magnetic immunity. capability of multiplexing, system integrity, remote sensing - these serve real-time health monitoring of the structures. Real-time strain measurement by the signal processing program is shown graphically and it gives a warning sound when the monitored strain state exceeds a given threshold level so that any sign of abnormal disturbance on the spot can be easily perceived.

• Applied Microscopy
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• v.36 no.spc1
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• pp.47-56
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• 2006

Improvements are made to existing primitive cell volume measurement method to provide a real-time analysis capability for the phase analysis of nanocrystalline materials. Simplification is introduced in the primitive cell volume calculation leading to fast and reliable method for nano-phase identification and is applied to the phase analysis of Mo-Si-N nanocoating layer. In addition, comparison is made between real-time and film measurements for their accuracy of calculated primitive cell volume values and factors governing the accuracy of the method are determined. About 5% accuracy in primitive cell determination is obtained from camera length calibration and this technique is used to investigate the cell volume variation in WC-TiC core-shell microstructure. In addition to chemical compositional variation in core-shell type structure, primitive cell volume variation reveals additional information on lattice coherency strain across the interface.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.273-278
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• 1999

A TDM-multiplexed fiber optic pressure/temperature sensor system utilizing fiber optic Fabry-Perot interferometers as sensing devices was developed and applied to measure water level variations and temperature variations. The maximum measurement speed of the system without saving measurement data is 4500 times per second and the response time of the sensors is thought to be ~ms. The difference between the theoretical value and the measured value for the scale factor of water level sensor and temperature sensor was +13.7%, -18% respectively. The nonlinearity of the sensors after calibration was less than 1%. The sensor system was applied to verify the capability of measuring the temperature variations and water level variations at a high speed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.780-789
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• 2008

A new method for measuring the performance of a micro-thruster is suggested in this paper. A few thrust stands have been developed for measuring micro-level thrusts. This paper describes a different measurement method that can minimize the calibration involved in the measurements, while providing the capability of directly measuring the produced minimum impulse bit directly. The underlying theory and the theoretical background for the measurement mechanism are described here. The theory and method is verified using a computer simulation, and the result is given in this paper. The theory has also been tested on an actual hardware. Although this hardware is a prototype, developed for proof-of-concept analysis, satisfactory results have been obtained.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.471-476
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• 1996

In this study, the method to use the phase shift keying (PSK) communication technique in smart transmitter is presented. In nuclear applications. smart transmitters for various parameters are expected to improve the accuracy of measurement and to reduce the load of calibration work. The capability of communication in field level is the most important merit of the smart transmitter. The most popular method is using of digital and analog techniques simultaneously - transmitting measurements from the field at 4∼20mA while modulating the current to carry digital information in both directions over the same twisted pairs. Conventional smart transmitters use the frequency shift keying (FSK) method for digital communication. Generally, however, the FSK method has the speed limit at 1200 bps. Amount of information to transmit becomes increasing as the processing technique is improved. The PSK method is noticeable alternative for high speed digital communication, but it has non-zero DC component. In order to use the PSK method in the field transmission with smart transmitter, the method to remove the DC component is studied in this work.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.105-113
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• 2017

KOLAS (KOrea Laboratory Accreditation Scheme) belongs to APLAC (Asia Pacific Laboratory Accreditation Cooperation). KOLAS manages the accreditation scheme for measurement traceability to SI units. As per June 2016, there are 22 KOLAS laboratories for liquid flow metering. Among them, 12 laboratories participated in the proficiency test (PM2015-08) for water flow metering, organized by KASTO (Korea Association of Standards and Testing Organizations). This proficiency test was performed with three kinds of flow ranges ($3.6m^3/h{\sim}12m^3/h$, $40m^3/h{\sim}80m^3/h$, $40m^3/h{\sim}200m^3/h$) considering the CMC (calibration and measurement capability) of the participating laboratories. The purpose of the proficiency test was to find out measurement equivalence of the CMC's between each participating laboratory and the reference testing laboratory (KRISS). The measurement equivalence was tested by the number of equivalence ($E_n$). If ${\mid}E_n{\mid}$ < 1, the measurement equivalence was established. All the participating laboratories passed this proficiency test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.341-350
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• 2006

In this paper, a new method for detecting breast cancer is proposed, which utilizes dielectric characteristics of pathological tissues and time delay of back scattered response, and its feasibility was investigated. We have developed a detection algorithm and verified it by numerical simulation and measurement for a prototype system. For a prototype system, we have fabricated experimental model(artificial breast with a cancer) and UWB(ultra-wideband) antenna. The results of the measurement simulation show an excellent detection capability of a cancer tissue. It is found that a good UWB antenna and a good calibration signal are key elements of such detection system. Further study is ongoing to develop a commercial system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.313-319
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• 2017

Fiber optics sensors that have been mainly applied to aerospace areas are now finding applicability in other areas, such as transportation, including railways. Among the sensors, the fiber Bragg grating (FBG) sensors have led to a steep increase due to their properties of absolute measurement and multiplexing capability. Generally, the FBG sensors adhere to structures and sensing modules using adhesives such as an epoxy. However, the measurement errors that occurred when the FBG sensors were used in a long-term application, where they were exposed to environmental thermal load, required calibration. For this reason, the thermal curing of adhesives needs to be investigated to enhance the reliability of the FBG sensor system. This can be done at room temperature through cyclic thermal load tests using four types of specimens. From the test results, it is confirmed that residual compressive strain occurs to the FBG sensors due to an initial cyclic thermal load. In conclusion, signals of the FBG sensors need to be stabilized for applying them to a long-term SHM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2334-2339
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• 2009

In case of an embedded system having an LCD panel with touch-screen capability, various figures such as rectangles, pentagons, circles, and arrows are frequently used for the delivery of user-input commands. In such a case, it is necessary to have an algorithm that can recognize whether a touched location is within a figure on which a specific user-input command is assigned. Such algorithms, however, impose a considerable amount of overhead for embedded systems with restricted amount of computing resources. This paper first describes a method for initializing and driving a touch-screen LCD and a coordinate-calibration method that converts touch-screen coordinates into LCD panel coordinates. Then it introduces methods that can be used for recognizing touched areas of rectangles, many-sided figures like pentagons, and circles; they are a range checking method for rectangles, a crossing number checking method for many-sided figures, a distance measurement method for circles, and a color comparison method that can be applied to all figures. In order to evaluate the performance of these methods, we implement two-dimensional graphics functions for drawing figures like triangles, rectangles, circles, and images. Then, we draw such figures and measures times spent for the touched-area recognition of these figures. Measurements show that the range checking is the most suitable method for rectangles, the distance measurement for circles, and the color comparison for many-sided figures and images.