• Economic and Environmental Geology
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• v.32 no.1
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• pp.93-100
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• 1999

In rock, there are many microsopic structures which influence the mechnical behavior of rock. Many microstructures interact with each other, and furthermore, material constants vary discontinuously within rock, as most rocks are composed of several minerals. Taking into account this feature, it may be possible to contemplate a microstructure of rock as a unit cell by which the rock is constituted periodically. If this idealization is acceptable, the homogenization method can be applied. In this research, various microcracks on rock specimens were observed through a stereoscopic microscope under uniaxial compression. On the other hand, local stress distribution in the periodic-micro structure was calculated by the homogenization method. Then it is shown that there is a possibility to establish a relation between the behavior of microcrack and macroscopic load quantitatively by the linear fracture mechanics.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.147-152
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• 1999

We have measured viscoelastic properties of fabrics in thickness direction. We assume that Maxwell model is very useful in stress relaxation of viscoelastic theories and appropriate formulas for fabric are calculated. Measurement system constitute of high precession load cell, translator and laser displacement sensor for viscoelastic properties was designed and elastic coefficients and damping coefficients were measured for 10 fabric samples. Elastic coefficients measured were 19~25 kN/㎡ and Damping coefficients measured were 4.8~8.7 MN$.$s/㎡. We concluded that these coefficients are good related with FUKURAMI collected from KESF system

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2008.10b
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• pp.634-642
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• 2008

Radio wave is the valuable resources in $21^{st}$ century. It will be widely used in various applications such as DMB, USN, telematics, and home network as well as mobile and wireless communications. Cognitive Radio technology is devised to maximize the utilization of radio resources by sensing near-by spectrum and dynamic and allocating free resources dynamically and adaptively. Wireless links for the secondary user need to be frequently switched to idle frequencies during the transmission of multimedia data in the cognitive radio based system. This may cause delay and information loss, and QoS degradations occur inevitably. The efficient frequency allocation scheme is necessary to support the seamless multimedia service to the secondary user while maintaining QoS of the primary user. This paper suggests a frequency selection scheme which considers other parameters such as cell load, data rate, and available bandwidth than just received signal strength during the frequency selection process. The performance of our proposed scheme is analyzed by simulation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.6-7
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• 2018

Although the importance of the construction lift is increasing, no improvements are being made to its operating system. This study proposed an optimal call-response algorithm of the construction lift for high-rise building construction by using image sensing technology, height measuring sensor, and load cell. This algorithm makes turn-around decision of the construction lift by considering the information and the number of user. It occurs when the call comes from a floor where the construction lift already have passed. The purpose of this study is to reduce the total latency of the construction lift user. Furthermore, it is possible to prevent delay in construction duration by carrying out a priority operation of the construction lift for the critical workforce.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.186-188
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• 1994

Fundamental characteristics of Giant Magnetostrictive Alloy Terfenol-D$(Tb_{0.3}Dy_{0.7}Fe_{1.9\sim1.95})$ were measured by experiments. Magnetostrictions of Terfenol-D samples whose lengths are 15 and 25 mm have been measured under compressive stress from 0 to 14 MPa, when the applied magnetic field was up to 1200 Oe. The relationship between magnetostriction and field is shown graphically in the form of $H-{\lambda}$, curve. For the experiment, solenoid magnet and lever-arm-type stress equipment were designed and fabricated. The magnetostriction is measured by laser displacement measuring system and the stress applied to the sample is measured by load cell.

• Food Science and Preservation
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• v.1 no.2
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• pp.99-105
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• 1994

To convert the analog signal from the drying process into the digital signal, the interface circuit was designed and built. To measure the weight and temperature during drying process, strain gauge type load cell and temperature transducer composed of pt 100 $\Omega$ thermometers and wheatstone bridge circuits were built and used. The temperature control device was composed of photocoupler and triac. Microcomputer aided experimental convective drying system was built with above cricuits and devices. Drying characteristics of onions can be estimated using this system.

• Journal of Auto-vehicle Safety Association
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• v.8 no.3
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• pp.5-9
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• 2016

The objective of this study was to find the factors affecting the results of full frontal barrier impact test for the NCAP (New Car Assessment Program). To find the factors, the frontal NCAP test results of the NHTSA (National Highway Traffic Safety Administration) were utilized. The three tested vehicle were same model year. It was observed the second peak value of barrier force affected the occupant injury risk. As the second peak value of the barrier force increases, the injury risk of the driver side occupant increases as well.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.180-184
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• 2009

A novel set of experimental test tooling for measuring pulling and holding forces for drawbeads on binders inclined at a wide range of angles is introduced. A mechanical design featuring a single load cell, a male-female draw bead set, translation and rotation degrees of freedom, and a screw-driven clamping system has been incorporated into a standard tensile test machine. On a real time basis, restraining and holding force data with respect to draw-in displacement may be directly downloaded into a PC for data processing. The proposed experimental system represents a significant breakthrough in drawbead simulation technology due to its relatively low cost, clever design, and versatility. The system is shown to yield excellent experimental data suitable for verifying theory and numerical model predictions.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1251-1252
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• 2006

In order to investigate 95% retained critical current of Bi-2223/Ag tapes under various stress-strain conditions, load cell attached tension and bending apparatus was used. The critical current of stress-strained tape was degraded below 95% retained critical current when tension and bending was simultaneously applied together. But only one of this tension or bending did not degrade the tape below 95% retained critical current. Deformation temperature was important to maintain the 95% retained Ic of Bi-2223/Ag tapes after bending or tension deformation because mechanical strength of tapes can be changed drastically between room temperature and 77 K.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.519-520
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• 2006

In this paper, we propose a voltage-controlled ring oscillator (VCO) for a 900 MHz low-noise fractional-N frequency synthesizer. The VCO delay cell is based on an nMOS source-coupled pair with load elements [1] and a combined tail current sources which consist of a large and a small current source to control the integer and fractional behaviors, respectively. The Spectre simulation results of the scheme in a 0.18um CMOS process show the accurate control of the KVCO better than the conventional one.