• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.401-407
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• 2006

In this paper, we present a small-sized and light weighted dual-band antenna for an access point of 2.4/5 GHz dual-band WLAN(Wireless Local Area Network). The antenna for WLAN should show the characteristic of omni-directional radiation pattern. First, to obtain the omni-directional radiation pattern the proposed dual-band antenna has an orthogonal inverted triangular type element at the center and locates four resonating elements symmetrically around it. Also, for the purpose of easy manufacturing and miniaturization of the antenna, we changed the central element which had the orthogonal inverted triangular type structure into the plate type. Measured $S_{11}$ for the proposed dual-band plate type antenna showed characteristic which was less then -12.8 dB for WLAN frequency bands. Measured results for the maximum gain showed 3.17 dBi at 2.44 GHz, 5.38 dBi at 5.77 GHz with omni-directional radiation pattern. The implemented antennas showed applicable performances for the access point of WLAN.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.45-51
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• 1993

An erbium doped fiber amplifier(EDFA) pumped by aingle 1.48$\mu$m LD was fabricated, and its gain and noise characteristics were measured. As a signal source, 1548 nm wavelength DFB LD was used. The small signal net gain of the EDFA module was 21.8 dB with maximum gain coefficient 0.7dB/mW for the erbium fiber length of 17.6 m, the pump power of 58 mW, and an input signal power of -25 dBm, respectively. The saturation power of the EDFA was 1 dBm for the input signal power of -5 dBm and the noise figure, measured by using an optical spectrum analyzer, was 5.8 dB for the input signal power of -40 dBm.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.489-490
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• 2006

This paper presents a switch type 2.4/5.8 GHz dual band low-noise amplifier, designed with $0.13{\mu}m$ RF CMOS technology. Using MOS switch allows the LNA to have two different input transconductance and output capacitance modes. Given supply voltage of 1.2 V, the simulation exhibits gains of 8.1 dB and 17.1 dB, noise figures of 3.1 dB and 2.57 dB and power consumptions of 13.0 mW and 10.2 mW at 2.4 GHz and 5.8 GHz, respectively.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.219-223
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• 2013

The purpose of this study was to determine the relationship between the spherical equivalent visual acuity (VA) and uncorrected astigmatism. On 108 emmetropic eyes, the spherical equivalent VA was measured for cross cylindrical lens (CC lens)-induced astigmatic eyes and the VA-astigmatism relation determined. On 158 astigmatic eyes, the spherical equivalent VA and corrected astigmatism were measured and the measured values were compared with the calculated values from the VA-astigmatism relation by correlation coefficient analysis. Subsequent to that, the relationship between spherical equivalent VA and uncorrected astigmatism was made. The relationship was fitted for an exponential equation. Correlation coefficient between calculated values by equation and measured values for astigmatic eyes was 0.991 (p<0.01). The relationship between the spherical equivalent VA and the uncorrected astigmatism was decided as follows (spherical equivalent VA / uncorrected astigmatism): 1.0 / 0.25 D, 0.9 / 0.50 D, 0.8 / 0.75 D, 0.7 / 1.00 D, 0.6 / 1.25 D, 0.5 / 1.50 D, 0.4 / 2.00 D, 0.3 / 2.50 D, 0.2 / 3.00 D, 0.1 / 4.00 D, and 0.05 / 4.75 D. In conclusion, the relationship table devised from this study is a useful reference for predicting uncorrected astigmatism by measurement of decimal VA in spherical equivalent.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.323-326
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• 1994

Three new sesquiterpene lactone glucosides named dentatins A, B and C were isolated from lxeris dentata and the structures were elucidated as $3{\betha}, {\;}8{\betha}-dihydroxy-(1{\alpha}, 5{\alpha})guainan-10(14)-ene-6{\alpha}, {;\}12-olide-3-O-{\betha}-D-giucopyuranoside{\;}(1), {\;}3{\betha}, {\;}8{\betha}-dihydroxy-(1{\alpha}, {\;}5{\alpha})-guaian-4(15), {\;}10(14)-diene-6{\alpha}, {\;}12-plide-3-O-{\betha}-D-glucopyranoside{\;}(3)$, respectively, on the basis of spectral evidence.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.17 no.2
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• pp.33-39
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• 2011

Background: The purpose of this study was to verify the most effective spinal stabilization exercise program by comparing the activities of muscles contributing to spinal stabilization during 2 types of exercises using 3-D NEWTON and a Gym-ball. Methods: We divided sixteen healthy students to two groups in D city were recruited and each subjects performed two type of exercise. Exercise 1 was performed 3-D NEWTON spinal stabilization training during 4 weeks (n=8). Exercise 2 was performed special training program that use a Gym-ball during 4 weeks (n=8). Results: The group of 3-D NEWTON applying lumbar stabilization kinetic program was increased 18.8s after training. Conclusions: It was revealed the statically significant difference between 3-D NEWTON and Gym-ball lumbar stabilization exercise groups. Therefore it has been turned out that 3-D NEWTON and Gym-ball lumbar stabilization exercise has an effect on the abdominis and trunk muscle strengthening and balance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.259-264
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• 2016

In this study, the properties of a patch antenna fed by a coplanar waveguide with ground (CPWG) and design method were studied. The antenna was impedance-matched to the CPWG feedline by adjusting the width, length, and position of the patch. To improve the frequency properties of the CPWG type antenna, patch length, patch width, patch position, and ground distance were simulated using HFSS (High Frequency Structure Simulator) simulation program. A CPWG antenna of 1.8 GHz for LTE band was designed and fabricated by photolithography on an FR4 substrate (dielectric constant of 4.4 and thickness of 0.8 mm). The fabricated antenna was analyzed using a network analyzer. The measured results agree well with the simulations, which confirmed the validity of this study. The fabricated CPWG antenna showed a center frequency, minimum return loss and -10dB bandwidth of 1.8GHz, -32.1dB, 22MHz and $50.2{\Omega}$ respectively. The proposed antenna is expected to be applicable to the LTE band.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.218-224
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• 2021

This study was conducted to determine the mass-loss rates and the changes in carbon/nitrogen (C/N) ratio of dead woods, which were of following species: Dryobalanops aromatic, D. rappa, and Cratoxylum arborescens. These were dominant tree species in mixed Dipterocarp forests (MDF) and peat swamp forests (PSF) in Brunei Darussalam. In May, 2019, 48 dead wood samples (15 cm×4.8 cm×5 cm) were placed in MDF and PSF sites, and all the samples were collected after 16 months. The effects of species on mass loss were statistically significant (p<0.05); however, no difference was observed in the mass loss obtained from the two forest types (p>0.05). The initial density (g·cm^-3) of the dead woods D. aromatic, D. rappa, and C. arborescens, was 0.64±0.02, 0.60±0.00, and 0.44±0.01, respectively. Also the annual mass loss rate (%) was estimated to be 6.37, 8.17, and 18.53 for D. aromatic, D. rappa, and C. arborescens, respectively. The proportion of dead woods in decay class III was only 25% of C. arborescens samples, which were attacked by wood-feeding invertebrates, such as termites. The C/N ratio decreased significantly in D. aromatic and D. rappa, but the decreasing trend of C/N ratio was not statistically significant in C. arborescens. The results indicate that physical traits of dead woods, such as density, could be one of the main factors causing the decomposition of dead woods initially, as invertebrates such as termites are one of the key decomposers of dead wood in tropical rainforests. In the samples of C. arborescens, which was attacked by invertebrates, nitrogen immobilization occurred to lesser extent as compared to that observed in D. aromatic and D. rappa.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.31-37
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• 2008

In order to organize the Intelligent Transport System(ITS) as a communication equipment, the satellite and wireless system demand broadband characteristics for collecting information from the wide road. Band-pass filters (BPF) or broad BPFs used in such communication system are required for broadband characteristics. This paper presents a design of such broad BPF which can be used in the system. Designed BPF which was difficult to get broadband characteristics after realization, become possible to realize filter with broad bandwidth and compact structure using parallel coupled line. The designed filter achieved the insertion losses improved by 0.4 dB and the return losses improved by 17.4 dB respectively with 60% of bandwidth at the 5.8 GHz of the center frequency, respectively.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.923-936
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• 2014

Images can be contaminated with different types of noise, for different reasons. The neighborhood averaging and smoothing by image averaging are the classical image processing techniques for noise removal. The classical spatial filtering refers to the aggregate of pixels composing an image and operating directly on these pixels. To reduce or remove effectively noise in image sequences, it usually needs to use noise reduction filter based on space or time domain such as method of spatial or temporal filter. However, the method of spatial filter can generally cause that signals of objects as the target are also blurred. In this paper, we propose temporal filter using the piece-wise quadratic function model and enhancement algorithm of image quality for the performance improvement of target detection and tracking by heterogeneous noise reduction. Image tracking simulation that utilizes real IIR(Imaging Infra-Red) images is employed to evaluate the performance of the proposed image processing algorithm.