• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.15-20
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• 2012

Field measurement is a very essential factor for economic aspect and estimation of stability of tunnels. In this paper, various types of support element based on field test data in 4-lane wide road tunnel were evaluated. And stability and economical efficiency were also estimated. The estimated value were compared with design value and the type of support element which is applicable to site condition was evaluated. The results show that most of support elements were modified under the standard value(30mm) and type of support element which is already constructed was overestimated. So, appropriate level of support element have to be presented to save the time and cost during construction.

• Journal of the Korean Geotechnical Society
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• v.38 no.8
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• pp.29-37
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• 2022

A three-dimensional analysis is required to interpret the drainage behavior of an improved ground with vertical drains, and the macroelement method enables efficient interpretation considering the three-dimensional drainage effect of vertical drains under two-dimensional plane strain condition. In this study, a novel finite element analysis program was developed by applying the macroelement method to the vacuum consolidation method used in ground improvement practice. The conventional macroelement method was used to calculate the amount of drainage from the vertical drain by setting the excess porewater pressure in the drainage material to zero; however, the program developed in this study was improved to consider negative excess porewater pressure as an actual vacuum consolidation condition. To verify the performance of the program, because of a comparison with the measurement values at the site where the vacuum consolidation method was applied, results predicted by the program and field measurement data showed similar settlement behavior.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.37-45
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• 2006

Bender elements, composed of thin piezo-ceramics and elastic shims, have been used to measure shear wave velocities of specimens in laboratories. In a preliminary stage of their field applications, an in-house research of optimizing suitable bender elements and their geometrical arrangement has been carried out in a barrel of kaolinite-water mixture. Two types of measurement configuration, similar to cross-hole and in-hole seismic testing, have been implemented. prototype instrumented rods were penetrated into a soft clay layer in the west coast and excellent shear waves were recorded. Development of penetration device (mandrel) and associated instrumented rods are in progress for deeper investigation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.37-42
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• 2016

This paper proposes a method to develop a high-precision dimension measurement system using a linear variable differential transformer sensor. The Dimension targets for measurement is carbon material vanes of key element in the rotating parts within vehicle circulating pump. Data acquisition system for dimension measurement is designed using the NI Compact RIO. And the program applying the dimension measurement algorithm is built using NI LabVIEW. The dimension measuring program is composed of a FPGA program, Real Time program and Host program. The method of the experiment compares master vane with target vane for measure the length of the carbon material vane. The experimental results confirmed the usefulness of the accuracy within ${\pm}4um$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.525-533
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• 1997

A nondestructive moisture measurement technique has been applied to improve the previous moisture measurement method in the building research. The experiment was done in free space using horns since it is the key element for continuous and non-destructive measurement. For this purpose a microwave bridge type analyzer at the frequency of 9.5 GHz was used to determine the moisture content of sands in the range of 1~12%. From this, the representative calibration curves were obtained. This shows that moisture measurement technique using microwave is applicabe to the measurement of moisture in non-metallic materials such as coal, pulp, foods, building materials, etc.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.55-64
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• 2003

Underwater acoustic noise measurement is an essential element for vulnerability assessment of modern naval platforms. But during the last few decades environmental conditions have drastically changed due to the gradually increasing sea ambient noise level and decreasing submarine radiated noise level. A real-time underwater acoustic measurement system with vertical line array is designed for the quiet submarine radiated noise assessment in challenging environment. This system has a constant directivity index in measurement frequency range and accurate tracking capability for the transmission loss compensation and navigation aids inside the submarine. This system has been validated at sea and used several times for the submarine noise measurement.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.594-599
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• 2004

In the sheet metal forming operations, the strain measurement of sheet panel is an essential work which provides the formability information needed in die design, process design, and product inspection. To measure efficiently complex geometry strains, the 3-dimensional automative strain measurement system, which theoretically has a high accuracy but practically has about 3～5％ strain error, is often used. For eliminating the strain error resulted in measuring the strains of formed panels using an automated strain measurement system, the position error calibration method is suggested, which computes accurate strains using the grids with accurate nodal coordinates. The accurate nodal coordinates are calculated by adding the nodal coordinates measured by the measurement system and the position error found using the multiple regression method as a function of the main error parameters obtained from the analysis of strain error in a standard cube. For the verification, the strain distributions of square and dome cups obtained from the position error calibration method are compared with those provided by the finite element analysis and ASAME.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.917-924
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• 2012

Noise power of large machineries, such as textile looms, winders, and twisting machines, is often measured in a reverberant space because they cannot be installed and operated in an anechoic chamber due to their size, weight, and operating conditions. Factors affecting the measurement error of an in-situ noise power measurement include the nonuniform reverberation time and the direction of sound intensity vector which is usually regarded as normal to the measurement surface. In this study errors due to these factors are estimated with the aid of numerical simulation based on the ray-tracing technique. The averaging of reverberation times measured at several points on the measurement surface is suggested to reduce the errors from nonuniform absorption. Also the direction cosine of each surface element is taken into account, which as a whole is represented as a solid angle of the measurement surface.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.66-69
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• 2017

The internal temperature of human-tissue transfers must be steadily maintained regardless of the external environmental changes. An ice pack and dry ice are the coolants for the transfer containers for which heat-insulating materials such as EPP (expended polypeopylene and EPS (expended polystrene) are used; however, changes of the external temperature/pressure and the melting of the coolants that is due to a long carriage result in changes of the internal temperature, and this makes it difficult to maintain the temperature. Accordingly, the thermoelectric element was used to design/manufacture a transfer container to maintain the internal temperature regardless of the external environmental changes. As a result of the measurement of the changes of the internal temperatures of the manufactured thermoelectric-element container and the EPS container over time, the internal temperature of the EPS container was increased, whereas the internal temperature of the thermoelectric-element container was maintained. The temperature of the distilled water that was poured into the containers indicated a pattern identical to that of the internal temperature.

• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.29-33
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• 2017

This paper proposes a half-mode substrate integrated waveguide (HMSIW) amplifier using lumped-element transition. The input and output impedances of this amplifier are matched by the lumped-element transition structure. This structure provides compact impedance and mode matching circuits between the HMSIW and a stand-alone amplifier. Surface mount technology inductors and capacitors are implemented to realize the lumped-element transition. A prototype of the proposed HMSIW amplifier shows 15 dB gain with 3 dB bandwidth of 4 to 7.05 GHz in a simulation and measurement.