• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.476-481
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• 2013

Ethylbenzene (EB) which has a similar physical properties with p-xylene (pX) was separated from EB/pX mixture by using MFI-type zeolite (TS-1, ZSM-5, and Silicalite-1) coated membranes. The zeolites were synthesized by microwave method to reduce the synthesis time and uniformly formed zeolite particles were coated on the ${\alpha}$-almina tubular support with a thickness of $3-4{\mu}m$. Separation factor and permeation flux of the synthesized zeolite coated membranes were measured to survey the best performance of ethylbenzene separation from different composition of EB/pX mixtures. When the EB/pX mixture of 5:5 molar ratio applied for the separation experiment, it represented the highest separation factor. We also have studied about the effect of the atomic composition of zeolites on the separation performance within the temperature range from 160 to $220^{\circ}C$. TS-1 showed the highest permeation flux of $1,666mol/m^{2*}s^*Pa$ and Silicate-1 showed the highest separation factor of 1.73 at $200^{\circ}C$ respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2479-2485
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• 2013

In this paper, we present a design for solid-state radar SSPA with sequential bias. We apply to variable extension pulse generator to eliminate signal distortion which is caused by bias rising/falling delay of power amplifier. There is an optimum impedance matching circuit to have high efficiency of GaN-power device by measuring microwave characteristics through load-pull method. The designed SSPA is consisted of pre-amplifier, drive-amplifier and main-amplifier as a three stages to apply for X-Band solid-state radar. Thereby we made a 200W SSPA which has output pulse maximum power shows 53.67dBm and its average power is 52.85dBm. The optimum design of transceiver module for solid-state pulse compression radar which is presented in this dissertation, it can be available to miniaturize and to improve the radar performances through additional research for digital radar from now on.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.10-15
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• 2008

In this paper, a new NMOS gate cross-connected current-mirror type bridge rectifier for UHF RFID applications is presented. The DC converting characteristics of the proposed rectifier are analyzed with the high frequency equivalent circuit and the gate capacitance reduction technique for reducing the gate leakage current due to the increasing of operating frequency is also proposed theoretically by circuitry method. As the results, the proposed rectifier shows nearly same DC output voltages as the existing NMOS gate cross-connected rectifier, but it shows the gate leakage current reduced to less than 1/4 and the power consumption reduced more than 30% at the load resistor, and it shows more stable DC supply voltages for the valiance of load resistance. In addition, the proposed rectifier shows high enough and well-rectified DC voltages for the frequency range of 13.56MHz HF(for ISO 18000-3), 915MHz UHF(for ISO 18000-6), and 2.45 GHz microwave(for ISO 18000-4). Therefore, the proposed rectifier can be used as a general purpose one to drive RFID transponder chips on various RFID systems which use specified frequencies.

• Polymer(Korea)
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• v.24 no.6
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• pp.860-868
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• 2000

In this work, the electro-magnetic interference (EMI) characteristics of PAN-based carbon fibers-reinforced composites are investigated with difference to manufactural parameters, i.e., fiber grade, fiber orientation angle, and laminating method. As a result, EMI shielding effectiveness (SE) of the composites greatly depends on a fiber orientation in composite angle. Especially, the fiber grade affects SE of composites in case of orientation angle of 0$^{\circ}$. Then the SE become greater as the change of electric character according to the arrangement directions, i.e., electrical anisotropy in the same constituent materials. This is due to the skin effect which is represented in the surface of electro-magnetic wave in high-frequency range. In all cases according to lamination methods, the composites represents SE of 83~98% over. Whereas, in symmetric and unsymmetric laminate structures, the SE decreases slightly as the laminate angles of composites increases. On the contrary. the repeating laminates structure shows the opposite tendency. Especially, 90$^{\circ}$ repeating laminate structure shows the SE more than 90% over the measuring frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.892-899
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• 2013

This paper discusses difficulties in precise measurements of the scattering parameters in (sub-)millimeter-wave range and tips for more accurate measurements, and provides measurement examples in the G-band(140~220 GHz). First, one investigates the differences in operating principles of scattering parameters measurement systems used in microwave and (sub-)millimeter-wave ranges and describes tips for better operation of the (sub-)millimeter-wave scattering parameters measurement system. In addition, one describes tips for better transmission properties and connection repeatability of waveguides and a precise measurement method for devices with small reflection coefficients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1653-1660
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• 2016

The synthetic aperture rardar (SAR) is an active sensor using microwaves. It transmits a microwave signal, called a chirp pulse, and receives the reflected signal in a moving platform such as satellite and unmanned aerial vehicle. Since this sensor uses microwaves that can penetrate the atmosphere, SAR generates the images regardless of light and weather conditions. However SAR operates on the moving platform, the Doppler shift and the side-looking observation method should be considered. In addtion, a residual image or ghost image can be occurred according to selection of the pulse repetition frequency (PRF). In this paper, a range design of the PRF for the L-band spaceborne SAR system is studied for prevention of SAR image distortion. And the system is studied for prevention of SAR image distortion. And the system parameter and the PRF are calibrated iteratively according to the proposed system design procedure and design constraints. The MATLAB based on SAR system simulator has been developed to verify the validity of calculated PRF. The developed simulator assumes that SAR sensor is operated by the PRF calculated from the design. The results of the simulator show that the targets in image has a valid peak to side-lobe ratio (PSLR) so that the PRF can be used for the spaceborne SAR sensor.

• Atmosphere
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• v.27 no.3
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• pp.359-370
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• 2017

In this study, the oceanic Total Precipitable Water (TPW) retrieval algorithm at 16 km altitude of High Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV) is described. Empirical equation based on Wentz method (1995) that uses the 18.7 and 22.235 GHz channels is developed using the simulated brightness temperature and SeeBor training dataset. To do radiative simulation, Satellite Data Simulator Unit (SDSU) Radiative Transfer Model (RTM) is used. The data of 60% (523) and 40% (349) in the SeeBor training dataset are used to develop and validate the TPW retrieval algorithm, respectively. The range of coefficients for the TPW retrieval at the altitude of 3~18 km with 3 km interval were 153.69~199.87 (${\alpha}$), 54.330~58.468 (${\beta}$), and 84.519~93.484 (${\gamma}$). The bias and RMSE at each altitude were found to be about $-0.81kg\;m^{-2}$ and $2.17kg\;m^{-2}$, respectively. Correlation coefficients were more than 0.9. Radiosonde observation has been generally operated over land. To validate the accuracy of the oceanic TPW retrieval algorithm, observation data from the Korea Meteorological Administration (KMA) Gisang 1 research vessel about six clear sky cases representing spring, autumn, and summer season is used. Difference between retrieved and observed TPW at 16 km altitude were in the range of $0.53{\sim}1.87kg\;m^{-2}$, which is reasonable for most applications. Difference in TPW between retrieval and observation at each altitude (3~15 km) is also presented. Differences of TPW at altitudes more than 6 km were $0.3{\sim}1.9kg\;m^{-2}$. Retrieved TPW at 3 km altitude was smaller than upper level with a difference of $-0.25{\sim}0.75kg\;m^{-2}$ compared to the observed TPW.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.8
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• pp.1221-1226
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• 2016

This study investigated changes in the S-allyl-L-cysteine (SAC) content of garlic using different cooking methods. Methods for determining SAC were validated by determining specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy using an high-performance liquid chromatography-fluorescence detection system. Results showed high linearity in the calibration curve with a coefficient of correlation ($R^2$) of 0.9999. The LOD and LOQ values for SAC were 0.15 and $0.47{\mu}g/mL$, respectively. The relative standard deviations for intra- and inter-day precision of SAC were less than 5%. The recovery rate of SAC was in the range from 97.35% to 97.47%. The SAC content of raw garlic was 2.77 mg/g, and there was no significant difference in SAC content according to blanching and microwave treatment. However, SAC content upon boiling and autoclaving at $110^{\circ}C$ and $121^{\circ}C$ increased from 3.50~9.16 mg/g, 6.52~16.21 mg/g, and 14.15~50.24 mg/g with increasing cooking temperature and time, respectively.

• Korean Journal of Remote Sensing
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• v.16 no.3
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• pp.221-233
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• 2000

An intertidal topography is continuously changed due to morphodynamics processes. Detection and measurement of topographic change for a tidal flat is important to make an integrated coastal area management plan as well as to carry out sedimentologic study. The objective of this study is to generate intertidal DEM using leveling data and waterlines extracted from optical and microwave remotely sensed data in a relatively short period. Waterline is defined as the border line between exposed tidal flat and water body. The contour of the terrain height in tidal flat is equivalent to the waterline. One can utilize satellite images to generate intertidal DEM over large areas. Extraction of the waterline in a SAR image is a difficult task to perform partly because of the presence of speckle and partly because of similarity between the signal returned from the sea surface and that from the exposed tidal flat surface or land. Waterlines in SAR intensity and coherence map can effectively be extracted with MSP-RoA edge detector. From multiple images obtained over a range of tide elevation, it is possible to build up a set of heighted waterline within intertidal zone, and then a gridded DEM can be interpolated. We have tested the proposed method over the Gomso Bay, and succeeded in generating intertidal DEM with relatively high accuracy.

• Journal of Oral Medicine and Pain
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• v.31 no.2
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• pp.155-165
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• 2006

The purpose of this study was to evaluate treatment outcome and prognosis of the patients with orofacial pain disorders who visited for treatment in the Department of Oral Medicine, Dankook University Dental Hospital from January 2002 to December 2004. Orofacial pain disorders were categorized into TMD(myogenous, arthrogenous and muscle-joint combined TMDs), neuropathic pain disorder, oral soft tissue disease and complex condition simultaneously having more and two aforementioned categories and treatment period, method and treatment outcome were evaluated. The results of this study were as follows; 1. Average longevity of treatment period was the longest in the neuropathic pain, followed by soft tissue disease, complex conditions, arthrogenous TMD, muscle-joint combined TMD and myogenous TMD in order. 2. When treatment methods were largely categorized into pharmacologic, physical and oral appliance therapy, pharmacologic therapy was used the most frequently for the patients with neuropathic pain or oral soft tissue diseases, oral appliance therapy for those with arthrogenous TMD and physical therapy for those with myogenous TMD. 3. Of physical therapeutic methods used in our clinic, EAST and microwave was employed the most frequently in the patients with myogenous TMD, ultrasound for those with arthogenous TMD and LLLT for those with neuropathic pain or oral soft tissue disease. 4. In comparison with change of pain after treatment, there existed a tendency that pain from neuropathic pain disorders persisted while pain from TMD was getting better or totally disappeared. 5. Concerning the change of mouth opening range in the TMD subgroups, there was no significant difference among the subgroups but significant difference existed among opening ranges, indicating comfortable maximum mouth opening increased the most following treatment. Improvement of active range of mouth opening was the most considerable in those with disc displacement without reduction. It can be said on the basis of the findings from this study that various treatments currently used for the orofacial pain showed good results with TMD in regards with pain control and improvement of function, suggestive of favorable prognosis, while neuropathic pain or soft tissue disease was the clinical conditions difficult to resolve, requiring a long and persistent treatment.