• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.108-117
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• 2004

In this paper, a measuring NDT(nondestructive testing) system using RUS(Resonant Ultrasound Spectroscopy) was built for nondestructive evaluation of the flaw in a ceramic Ferrule. The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. The RUS system is the measuring which is to exite specimen and to inspect the difference of natural frequency pattern between acceptable specimen and specimen which has some defects. RUS system is configured of spectrum analyzer, power amplifier, PZT sensor and support frame. For defect evaluation by the RUS, we performed to measure natural frequency of Ferrule, both acceptable and cracked. In the case of Ferrule, the resonant frequency of cracked-Ferrule existed to higher frequency band than acceptable-Ferrule.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.897-898
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• 2006

This paper presents test results for the speed control system of PMSM (Permanent Magnet Sychronous Motor). The PMSM has higher efficiency and torque per volume than other motors because PMSM use permanent magnet of high energy density instead of field winding. In this paper, current and speed control of PMSM using DSP was accomplished.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.1
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• pp.44-54
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• 1993

This is an experimental study to identify the performance of air-to-air rotary heat exchanger with polyurethane foam matrix. The experimental apparatus including heating AHU(Air Handling Unit), cooling AHU, sensor chamber, and heat exchanger testing unit was designed and manufactured in this study. The performance of heat exchanger with porous polyurethane foam matrix was tested with variations of the density and the thickness of matrix, regulating the wind velocity and the rotational speed of matrix. The actual heat recovery effectiveness, air leakage rate, and pressure drop of heat exchanger were measured and analyzed.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.503-510
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• 2006

The measurement of specific gases is based on the reversible conductivity change of sensing materials in semiconductor type gas sensors. For an application as gas sensors of high sensitivity, porous $SnO_2$ films have been fabricated by anodizing of pure Sn foil in oxalic acid and characteristics of anodic tin oxide films have been investigated. Pore diameter and distribution were dependent on process conditions such as electrolyte concentration, applied voltage, anodizing temperature, and time. Characteristics of anodic films were explained with current density-time curves.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.10
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• pp.50-62
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• 1996

A parallel looking stereo camera was mainly used as an input sensor for digital image processing, image understanding and the extraction of 3 dimensional information. Theoretical analysis and performance evaluation are dealt in this paper for a convergent looking stereo camera model having a fixation point with the result of crossing optical axes. The quantization error, depth resolution and equidepth map due to digital pixels, and the misalignments effects of pan, tilt and roll angles are analyzed by using rhe relationship between the reference and image coordinate systems. Also horopter, epipolar lines, probability density functions of the depth error, and stereo fusion areas for the two camera models are discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.37-39
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• 2015

The ships transiting the Northern Sea Route (NSR) have been gradually increased so that the number of ship-ice collision accidents would be increased. The collision between ship and ice floe can lead to serious damage of hulls and decline of ship's maneuverability. In this study, collision tests that a model ship is forced to collide with disk-shaped synthetic ice floes are conducted in a towing tank. The synthetic ice floes made of polypropylene which has similar density with real ice are used. The ice load is measured by a load cell installed on the carriage rod. The ice floe's motion is measured by a motion sensor installed on the synthetic ice floe. The influences of contact conditions such as hull form and ship speed on the ship-ice collision response are investigated and discussed by measured peak force and ice floe's motion.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.405-410
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• 2006

We fabricated gas sensors using carbon nanotubes (CNTs) as electron emitters for the purpose of detecting inert gases. By using the silicon-glass anodic bonding and glass patterning technologies with the typical Si process, we improved the compactness of the sensors and the reliability in process. The proposed sensor, based on, an electrical discharge theory known as Paschen's law in principle, works by figuring the variation of the discharge current depending on gas concentration. In the experiment, the initial breakdown characteristics were measured for air and Ar as a function of gas pressure. As the result, even though it should be realized that there are many other factors which have an effect on the breakdown of a gap, the sensors led to similar result as predicted by Paschen's law, and they showed a possibility as gas sensors which enable to detect the gas density ranged to the vacuum pressure from 1 to $10^{-3}$ Torr.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.189-192
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• 2009

The leakage current in a CMOS image sensor (CIS) can have various origins. Leakage current investigations have focused on such things as cobalt-salicide, source and drain scheme, and shallow trench isolation (STI) profile. However, there have been few papers examining the effects on leakage current of nitride stringers that are formed by gate sidewall etching. So this study reports the results of a series of experiments on the effects of a nitride stringer on real display images. Different step heights were fabricated during a STI chemical mechanical polishing process to form different nitride stringer sizes, arsenic and boron were implanted in each fabricated photodiode, and the doping density profiles were analyzed. Electrons that moved onto the silicon surface caused the dark leakage current, which in turn brought up the speckle defect on the display image in the CIS.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.378-385
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• 2001

This paper deals with the effect of an adjacent viscous fluid on the torsional vibration of a circular rod excited by a transducer at one end. The interaction between the torsional vibration of the rod and the fluid has been studied theoretically and expressed in terms of the mechanical impedance. The theoretically-obtained trend that the mechanical impedance is proportional to the square root of the viscosity times density of the fluid has been confirmed by the impedance measurement. The paper demonstrates that a torsionally-vibrating rod can be used as a sensor measuring the viscosity of a fluid.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.353-354
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• 2014

무선 센서 네트워크(WSN)환경에서는 저가의 센서 노드를 구성하기 위해 배터리, 제한된 에너지 등과 같은 하드웨어적인 제약을 갖고 있다. 특히, 센서 노드의 제한된 에너지는 네트워크 수명과 직접적인 관련이 있기 때문에 네트워크의 수명을 연장하기 위한 효율적인 기법들이 요구되는 실정이다. 이를 위해 본 논문에서는 WSN환경에서 고정 노드와 모바일 노드를 혼용하여 음영지역을 최소화할 수 있는 모바일 노드 이동 기법을 제안한다. 이는 대표 노드를 선정하여 네트워크의 밀도를 제어하고 각 노드들의 거리에 따라 신호 세기를 제어한다. 이를 통해 네트워크 지역의 확장과 각 노드의 에너지를 효율적으로 사용할 수 있다.