• Korean journal of food and cookery science
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• v.22 no.3 s.93
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• pp.299-306
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• 2006

The numerous varieties of coffee beans contain a wide range prices and qualities. While the varieties of green coffee beans can generally be distinguished by their appearance, this visual criterion is impossible after the roasting process. Therefore, we need to develop a classification method or device. In this study, the potential of a new type of electronic nose, fast gas chromatography based on a surface acoustic wave sensor(SAW), was evaluated for the classification of origins and blended commercial brands in roasted coffee beans. Eight blended commercial brands and the origins of four similarly roasted ground coffee beans(with no significant difference of color) were rapidly(90 sec/sample) classified. The reproductive results were easily understandable over the aroma image pattern by $VaporPrint^{TM}$. In conclusion, GC-SAW electronic nose can be applied to the classification of origins and commercial brands in roasted ground coffee beans and to e evaluation of the similarities and differences of volatile pattern between samples.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.37-44
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• 2012

This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.393-396
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• 2000

기존의 탄성표면파 듀플렉서 필터는 1/4 파장 정합선로를 이용한 격리회로를 이용하기 때문에 패키지 상에 스트립라인을 구성하는 제작상의 어려움이 있다 본 연구에서는 격리회로가 송신용, 수신용 필터와 함께 온칩상에 위치할 수 있는 새로운 형태의 탄성표면파 필터를 설계하였다. 그 과정으로 송수신 대역을 각각 담당하는 사다리형 필터를 설계하였고, 집중소자 즉, 인덕터와 캐패시터로 구성되는 탄성표면파 듀플렉서 필터의 격리회로를 구성하였으며, 우수한 성능을 가질 수 있도록 각각의 집중소자들의 값을 최적화하였다.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.224-229
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• 2011

In this study, we have developed shear horizontal(SH) surface acoustic wave(SAW) sensors for the detection of immunoglobulin G(IgG) on the gold coated delay line of SH-SAW devices. As the result of the experiment, we could uniformly immobilize anti-MIgG(mouse IgG) conjugate on the surface of gold. When displaying results of immobilization on the surface of gold using G-anti MIgG conjugate and blocking buffer in frequency shift, G-anti MIgG conjugate showed frequency shift of 75.1 kHz in the initial frequency, and blocking buffer showed frequency shift of 215.7 kHz. When various concentrations of MIgG was added in 100MHz type sensor, the sensor showed 46.3, 127.45, 161.21 and 262.39 kHz frequency shift at 25, 50, 75 and 100 ${\mu}g$ MIgG concentration, respectively.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.40-42
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• 2000

This paper presents a new method of segmenting a one-dimensional signal into a set of features of type(line, Vee-groove, Lap-joint and etc.), A set of requirements for the segmentation process result from the application area, which in this case are laser welding, GMAW(Gas Metal Arc Welding), SAW(Submerged Arc Welding) and high speed tack welding. The algorithm is able to detect an exact welding position in the presence of noise and missing data, yet is reasonably economical to implement

• Journal of the Korean Institute of Gas
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• v.14 no.4
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• pp.56-62
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• 2010

The purpose of this paper analyzes and investigates the failure case studies of electronic control sensors for a LP gas engine. The malfunction of crank angle sensor, which controls a fuel injection volume of LP gas, displays an irregular and non-uniform pulse wave form. The pulse form, which is related to the noise of the crank angle sensor, displays at the rectangular peak with a saw-toothed shape and is intermittently generated with a level of 2.46V noise signal. The malfunction of No. 1 TDC sensor in which is caused from the internal disorder affects to the reduction of engine power and engine stop suddenly. If the malfunction of oxygen sensor is occurred due to a wiring problem of a sensor connector, the LP gas vehicle may produce a shaking and disharmony of an engine because of no signal supply from the oxygen sensor. The air cleaner replica produces the clogging of continuous supply of fresh air. This may cause the retardation of vehicle acceleration and engine disharmony intermittently.

• Food Science and Preservation
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• v.20 no.4
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• pp.554-563
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• 2013

The changes in quality properties and nutritional components for two mugworts, namely, Artemisia capillaris Thumberg Artemisiae asiaticae Nakai fermented by Bacillus strains were characterized followed by rapid pattern analysis of volatile flavor compounds through the SAW-based electronic nose sensor in the GC system. After fermentation, the pH has remarkably decreased from 6.0~6.4 to 4.6~5.1 and there has been a slight change in the total soluble solids. The L (lightness) and b (yellowness) values in the Hunter's color system significantly decreased, whilst the a (redness) value increased via fermentation. The HPLC analysis demonstrated that the total amino acids increased in quantity and the essential amino acids were higher in the A. asiaticae Nakai than in the A. capillaris Thumberg, specially with high contents of glutamic and aspartic acid. After fermentation, the monounsaturated fatty acid increased in the A. asiaticae Nakai and the polyunsaturated fatty acids increased in the A. capillaris Thumberg. While the total polyphenol contents have not been affected by fermentation, the total sugar contents have dramatically decreased. Scopoletin, which is one of the most important index components in mugworts, was highly abundant in the A. capillaris Thumberg; however, it was not detected in the A. asiaticae Nakai. Small pieces of plant tissue in the surface microstructure were found in the fermented mugworts through the use of the scanning electron microscope (SEM). Volatile flavor compounds via electronic nose showed that the intensity of several peaks has increased and additional seven flavor peaks have been produced after fermentation. The VaporPrintTM images demonstrated a notable difference in flavors between the A. asiaticae Nakai and A. capillaris Thumberg, and the fermentation enabled the mugworts to produce subtle differences in flavor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.156-160
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• 1997

This paper introdues the development of hydraulic cylinder with magnetic sensor detecting absolute and precise position for automation of excavator. The system which is developed can detect absolute position witha little displacement by using algorithm for recognizing datum points, 1/4 divider algorithm and high precision algorithm improved position precision and robustness to noise etc. The solenoid valve and PWM control using saw-toothed wave are used for absolute position control of cylinder, respectively

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.320-323
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• 2002

This paper presents a new generation of system for pressure vessel and shipbuilding. Typical pressure vessel and ship building weld joint preparations are either traditional V, butt, fillet grooves or have narrow or semi narrow gap profiles. The fillet and U groove are prevalently used in heavy industries and shipbuilding to melt and join the parts. Since the wall thickness can be up to 6" or greater, welds must be made in many layers, each layer containing several passes. However, the welding time for the conventional processes such as SAW(Submerged Arc Welding) and FCAW(Flux Cored Arc Welding) can be many hours. Although SAW and FCAW are normally a mechanized process, pressure vessel and ship structures welding up to now have usually been controlled by a full time operator. The operator has typically been responsible for positioning each individual weld run, for setting weld process parameters, for maintaining flux and wire levels, for removing slag and so on. The aim of the system is to develop a high speed welding system with multitorch for increasing the production speed on the line and to remove the need for the operator so that the system can run automatically for the complete multi-torch multi-layer weld. To achieve this, a laser vision sensor, a rotating torch and an image processing algorithm have been made. Also, the multitorch welding system can be applicable for the fine grained steel because of the high welding speed and lower heat input compare to a conventional welding process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1019-1025
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• 2003

There are many kinds of seam trackers in the industrial welding field. We are proposed the contact seam tracking sensor applying strain gauges kind of contact sensor that mostly used in welding part now. For this seam tracking experiment, we made the strain gauges sensor by ourselves and tested how well the sensor tracks the seam. The experiment device consist of strain gauges sensor, amplifier circuit of strain gauges signal, saw wave generator, MOSFET power diving circuit and X-Y slide by moved DC motor. The tracking areas are X-Y planes(left, right, up and down) and the change of strain gauge resistance causes to move DC motor that connected to X-Y slide. As a result of experiment, we confirmed that the strain gauges sensor tracks a seam well, and X-Y slide DC motor was controlled by PWM control.