• Proceedings of the KSME Conference
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• 2008.11a
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• pp.322-326
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• 2008

In this paper, we have studied the images which have been reconstructed by using combination of images acquired by the variation of operating frequency. When inner images have been reconstructed, they have been superposed by the surface state effect. In this case, the images of the phase object can be enhanced by the contrast of inner images. There is a kind of specimen, one is a reference block having 1/4T, 1/2T, 3/4T side drilled holes as main run piping material of the steam generator in nuclear power plants. It has been shown that the two results of defect shapes have better than before in this processing and phase contrast grow about twice. And we have constructed the acoustic microscope by using a quadrature detector that enables to acquire the amplitude and phase of the reflected signal simultaneously. Further more we have studied the reconstruction method of the amplitude and phase images, the enhancement method of the defect images' contrast.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.655-659
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• 2010

In the conventional PNC scheme, the relay node requires simultaneous transmission of two source nodes with strict power control and carrier-phase matching between two received symbols. However, this pre-equalization process at source nodes is not practical in fading channels. In this letter, we propose a novel physical-layer network coding (PNC) scheme with log-likelihood ratio (LLR) conversion for fading channels, which utilizes not pre-equalizer at transmitters (source nodes) but joint detector at receiver (relay node). The proposed PNC requires only channel side information at the receiver (CSIR), which is far more practical assumption in fading channels. In addition, the proposed PNC scheme can use the conventional modulation scheme like M-QAM regardless of modulation order, while the conventional PNC scheme requires reconfiguration of modulation scheme at the source nodes for detection of the received signal at relay node. We consider the combination of the proposed PNC and channel coding, and find that the proposed PNC scheme is easily combined the linear channel codes such as turbo codes, LDPC, and convolutional codes.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.165-169
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• 2014

An existing infrared (IR) analysis system is generally composed of infrared source, IR focusing lenses, IR detector, and optical chopper. An optical chopper is widely used in combination with lock-in amplifier to improve the signal-to-noise ratio by periodically interrupting incident light beam. During recent years, a few researches on miniaturized optical chopper have been reported to apply to micro-scaled optical systems. In this paper, a micro optical chopper operated by electromagnetic actuation is proposed and applied to a miniaturized micro-scaled optical system operating in IR spectral range. Additionally, the fabrication method of the proposed micro chopper is demonstrated. The proposed micro optical chopper is composed of the polydimethylsiloxane (PDMS) membrane, solenoid, and permanent magnet. The permanent magnet is bonded on the PDMS membrane using an ultraviolet-activated adhesive. The operation of the chopper is based on the attractive and repulsive forces between permanent magnet and solenoid induced by an electrical current flowing through the solenoid. The fabricated micro optical chopper could operate up to 200 Hz of frequency. The maximum operating distance of the chopper with 7mm diameter membrane was $750{\mu}m$ at 100 Hz of frequency.

• The Korean Journal of Food And Nutrition
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• v.13 no.2
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• pp.118-124
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• 2000

Lipoxygenase(LOX) in soybeans is responsible for beany flavors which limit the wide utilization of soybeans to foods. This study was conducted to analyze beany flavor compounds of the normal Hwagkeumkong and LOX-deficient soybean cultivars, Jinpumkong which lacks L-2, L-3, and Jinpumkong 2 which lacks all L-1, L-2, L-3. Using the combination of dynamic headspace sampling and gas chromatography-mass selective detector(DHS-GC-MSD) for analyzing volatile compounds, hexanal and hexanol were identified in whole soy flour of all three soybena cultivars. Hwangkeumkong had more volatile compounds than Jinpumkong and Jinpumkong 2 in defatted soy flour. Hexanal and acetic acid were identified in soy milk of all three soybean cultivars but Hwangkeumkong had more volatile compounds than Jinpumkong 2. From the analysis with a static headspace sampling(SHS) and GC-MSD the major compounds were hexanal, acetic acid, 1-hexanol, and 1-octen-3-ol. The content of acetic acid was similar among three cultivars. But contents of hexanal and pentanal in Jinpumkong 2 were less than that of Jinpumkong and Hwangkeumkong. Using GC-FID, Jinpumkong 2 had less contents of hexanal and pentanol than Hwangkeumkong in whole soy flour and defatted soy flour. In this study, LOX-deficient soybean cultivars showed less hexanal, pentanol and other compounds than the normal Hwangkeumkong. However quite amount of beany flavor compounds were identified in Jinpumkong and Jinpumkong 2. So further studies are required to characterize LOX isozymes, to understand the mechanisms of beany flavors production, and to develop some other methods for removing beany flavor.

• Food Science of Animal Resources
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• v.21 no.3
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• pp.256-264
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• 2001

Pyrolysis/GC-mass spectrometry(Hewlet-Packard 5890GC/mass selective detector, 5971 BMSD), interfaced to a CDS Pyroprobe 1500 was optimized for rapid analysis of flavour compounds in Cheddar cheese. Twenty flavour compounds, including aldehydes(4), ketones(4), fatty acids(10), alcohol(1), and hydrocarbon(1), were identified from Cheddar cheeses. In total, Twenty-three flavour compounds aldehydes(2), ketones(8), alcohols(3), fatty acids(7), lactone(1), benzene derivative(1) and amide(1) were identified from two samples of accelerated-ripened Cheddar cheese treated with the proteolytic enzymes of Lactobacillus casei LGY. In total, Twenty-one flavour compounds; aldehydes(2), ketones(5), alcohols(2), fatty acids(11), and lactone(1) were identified from enzyme-modified cheese(EMC) treated with the combination of the proteolytic enzymes of Lactobacillus casei LGY and commercial endopeptidase or lipase. However, All the flavour compounds identified by pyrolysis/GC/MS in samples of ARC and EMC were not determined whether they are recognized as typical Cheddar flavour or not. More studies were requested on the development of methods for a rapid and convienent analysis of dairy fermented products using pyrolysis/GC-mass spectrometry.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.10
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• pp.452-457
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• 2006

In this paper, an algorithm to detect steps in hemiplegic patients using a 3-axis accelerometer a紅ached on the trunk was proposed. The proposed algorithm consisted of the signal pre-processing, the step detector, the classification of steps and the calculation of stride time. Two FIR band-pass filters were designed and steps were measured by the combination of filtered signals in the vertical and the anteroposterior directions. In addition, the classification of steps and the calculation of stride time were computed by using the detected steps and lateral signals. For the experiment, fourteen hemiplegic patients were participated and the linear accelerations of the trunk and foot switch signals were measured synchronously. To evaluate the system performance, the detected steps and initial contacts by the foot switch were compared. The average error between the steps and initial contacts was 0.024ms and the difference of the average stride time was 0.01s. Finally, all gait events were detected exactly. Results showed that the accelerometry could use for the gait evaluation in clinical rehabilitation therapies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.356-362
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• 2003

In this paper, we propose a predistortion technique which uses a novel combination of the second harmonic technique and the difference frequency technique to achieve independent control of the 3rd and 5th order intermodulation products generated by the PA. The second harmonic and difference frequency terms are generated using an envelope detector and two frequency multipliers. The RF predistorter has capability to independently control of the 3rd and 5th order intermodulation products so that high power amplifier is optimized for linear characteristics. From the measurement results, over the frequency band 2137.5 MHz to 2142.5 MHz, ACPR reduction of 11 dB is obtained for a single 30 dBm W-CDMA carrier.

• The Journal of Korean Medicine
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• v.20 no.1 s.37
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• pp.44-51
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• 1999

Analysis of residual pesticides in herbal drugs was performed by GC-ECD and GC-MS. Especially, selected ion monitoring(SIM) technique was applied to increase the GC/MS sensitivity. Analysis of residual pesticides was determined sensitivity and selectively without any internal standard by setting the SIM technique to their characteristic fragments for quantitation ion and confirmation ion. The combination of two detector, GC-ECD and MS-SIM technique, is abailable for determining a multiclass residual pesticides in herbal drugs. The average recoveries through the method were $65.9%{\sim}99.7%$ in herbal drugs. The data of gas chromatographic analysis was compared with the limits of residual pesticides in herbal drugs and agricultural foods. 4. 4-DDT was detected above the limits to the residual pesticides in herbal drugs. Diazinon and EPN were detected, but the limits of residual pesticides were less than that of agricultural foods.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.176-180
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• 2001

In this paper, we have studies the images have been reconstructed by using combination of images which has been acquired by the variation of operating frequency. When inner images has been reconstructed, inner image has been superposition by surface state effect. In this case, image enhancement the phase object and enhance the contrast of inner image. In the result of the specimen for the round defect with 2mm diameter, for the types of the depth are 1.5mm, 2mm, 2.5mm, and 3mm, it has been show that the shape of defect has better than before this processing and phase contrast grow large twice. And we have constructed the acoustic microscope by using quadrature detector that is able simultaneously to acquired the amplitude and phase of the reflected signal. Father more we have studied the reconstruction method of the amplitude and phase images and the enhancement method of the defect images' contrast.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.94-101
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• 2004

From the Beckmann's reflection model of wave incident, reflected light from a surface is known to have not only specular but also diffuse components. The specular component dominant a surface for a mirror-like surface is distributed on the almost the same area as the spot on the surface, but the diffuse component region dominant f3r a rough surface spreads scattered on the larger areas than the spot. Therefore, statistic parameters from the scattered light distribution are more meaningful in the diffuse region, while the magnitude of rather meaning in the specular region. In usual, there need two sensors to acquire two kinds of information: Photo-detector for light intensity magnitude and image sensor for light intensity distribution. But dual sensor scheme requires a beam splitter usually to feed light to each sensor, and moreover there is not a combination rule to relieve the different sensor characteristics. In this study a new method is proposed for acquisition of the dual information using only an image sensor. Specular region is established on an image area being distinguished from a diffuse component, and laser power is adjusted so that no pixel of the image sensor in the specular region is saturated. Simulation based on the light reflection theory and the experimental results are quite well matched, and thus the proposed method was proved to be very useful for mirror-like surface measurement.