• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.199-205
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• 2017

In a small cell base station used in densely populated areas, a dual polarized multiple antenna(MIMO) is mainly used to increase the cell capacity. This paper demonstrates a dual-polarization antenna with high cross-polarization discrimination(XPD) that can improve the capacity of a small cell using a dual polarization multiple antenna (MIMO). By using the symmetric structure and differential feeding, high XPD in all directions is achieved. In addition, a very similar radiation pattern is observed between each polarization. Because of high XPD and similar radiation pattern in all directions, proposed antenna is well adopted for small-cell multiple-input multiple-output(MIMO) system. Experimental results shows that the proposed antenna has a bandwidth of 180 MHz (2.51~2.7 GHz), a maximum gain of 4.5 dBi (3.5~4.5 dBi), and a half-power beam width of 85 degrees. In addition, average XPD of 26.4 dB in all directions, more than 13.8 dB increase than previous dual-polarization antennas which use single emitter by using different feeding or selectively use polarization through switching.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.19 no.1
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• pp.20-30
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• 1993

Liquid Chromatographic behavior of Pd(II) in Isonitosoethylacetoacetate imine IEAA-NR: R=H, CH3, C2H5, n-C3H7, n-C4H9, C6H5-CH2) Chelates were investigated by reversed phase high performance 1iquid chromatography on Micropak MCH-5 Column using Methanol /water as mobile phase. The optimum condition for the separation of Pd-Isonitrosoethylacetoacetate imine chelates were examined with respect to the flow rate, mobile phase strength. It was found that Pd(IEAA-NR)2 chelates were eluted in an acceptable range of the capacity factor value (0 $\leq$ log k' $\leq$ 1), The dependence of the logarithm of capacity factor(k') on the volume fraction of water in mixture with in the binary mobile phase was examined. Also, the dependence of k'on the liquid-liquid extraction distribution constant in methanol-water / n-alkane extraction system was on system was invert tigated for Pd(IEAA-NR)2. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates be largely due to the solvophobic effect.

• Microbiology and Biotechnology Letters
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• v.7 no.1
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• pp.37-46
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• 1979

In order to investigate the compositional change of the lauan and pine sawdust media during the coltivation of oyster mushroom (Pleurotus ostreatus) chemical components of the two media and mushroom were analized periodically from spawning to ending. The results are summerized as follows: 1) The total yield of mushroom from the lauan sawdust media was 6.39 kg/$m^2$, and from the Pine saw-dust media 6.31 kg/$m^2$, 94％ of which was produced from the first and second cropping period. 2) In both media ash content increased gradually, while organic matter content decreased as the cultivation progressed. Moisture content, which was about 79％ at the time of spawning, decreased a little during the priod of mycelial propagation, after which no change was observed. 3) Total nitrogen content of the two media decreased gradually as the cultivation progressed, and total loss of insoluble nitrogen was greater than that of soluble nitrogen. Amino nitrogen content tended to increase continually. 4) In both media pentosan, $\alpha$-cellulose, lignin and C/N ratio decreased gradually, while the content of reduced sugar, trehalose and mannitol continued to increase. 5) In both media phosphorus, potassium, manganese and zinc decreased, and magnecium, calcium, iron and copper showed irregular changes. 6) CMC-saccharifying and liquefying activity gradually increased from after mycelial propagation to the second cropping, after which it decreased in both media. Xylanase activity rapidly and greatly increased during the second cropping period rather than the first period. At the start of the third cropping period the activity decreased slowly. Protease activity was highest after mycelial propagati, after which it gradually decreased. The pH of the two media decreased as the cultivation progressed. 7) In both media little change was observed in the content of the components of mushroom cropped from the first to the third period, but slight decrease was noticed at the fourth cropping.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.491-500
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• 2017

Stream water quantity is the most basic, fundamental and important element for stream water quality and for conservation of ecological environment. This study aims to analyze causes of changes in stream water quantity based on the percentage of impervious surface area (%ISA) in urban streams of Gyeonggi-do, and also to present a method to secure water quantity of urban streams in Gyeonggi-do and data to be applied to River Management Policy. For this purpose, the Anyangcheon watershed, the Tancheon watershed, and the Osancheon watershed were selected as samples of the urban streams. In addition, the stream water quantity and the changes in stream water quality which were based on the amount of ISA, and methods to directly and indirectly secure stream water quantity were investigated. The results are as follows. The amounts of ISA of the Anyangcheon watershed, of the Tancheon watershed, and of the Osancheon watershed showed a 5.32%, 6.32%, and 7.22% increase, respectively, from 2014 which was approximately 10 years ago. The runoff coefficient generally increased as the amount of ISA was increased. Water reuse quantity of stream in the Tanchon watershed had a positive effect on securing stream water quantity, but both in the Anyangcheon watershed and in the Osancheon watershed, it did not have a positive effect on that. However, water reuse quantity of stream improved the water quality of each stream.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1183-1189
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• 2014

The accuracy of the resistive-sheet technique in calculating the RCS(Radar Cross Section) of a deciduous leaf is examined in this paper for various thicknesses and dielectric constants, and a range of thicknesses for the resistive sheet technique is proposed. At first, a leaf was assumed to be a lossy dielectric disk, and the dielectric disk was again assumed to be a resistive sheet with an appropriate resistivity for a given thickness, a dielectric constant, and a frequency. Then, the RCS of the leaf was computed using the physical optics(PO) method, and was compared with the calculation results of a numerical analysis: i.e., a commercial tool based on the FEM (Finite Element Method) technique. It was shown that the error increases as the thickness increases. The error was 0.1 dB, for example, when the thickness is 1.2 mm and 3.7 dB when the thickness is 3 mm with a dielectric constant of(21.4, 9.7) at 9.6 GHz. It was also found that the error decreases as the dielectric constant increases. This study will be very useful for calculating the scattering characteristics of numerous leaves in a vegetation canopy for estimating its radar backscatter using scattering model.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.426-434
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• 2022

Bubbles generated by various causes in the ocean are known to persist for long periods of time. Although the volume occupied by bubbles in the ocean is small, the presence of bubbles in ocean due to resonance and attenuation greatly affects the acoustic properties. Accordingly, bistatic reverberation experiment was performed in the ocean where artificial bubbles exist. A number of transducers and receivers were installed on 6 buoys arranged in a hexagonal shape, and blowing agents were dropped in the center of the buoy to generate bubbles. For reverberation modeling that reflects acoustic characteristics changed by bubbles, the spatial distribution of bubbles was estimated using video data and received signals. A measurement-based bubble spectral shape was used, and it was assumed that the bubble density within the spatial distribution of the estimated bubble was the same. As a result, it was confirmed that the bubble reverberation was simulated in a time similar to the measured data regardless of the bubble density, and the bubble reverberation level similar to the measured data was simulated at a void fraction of about 10^-7 ~ 10^-6.8.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.35-40
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• 2023

For the EMC test, the radiation characteristics and immunity characteristics of the EUT are measured under the condition that the EUT maintains its normal operation. For normal operation of the EUT, it is necessary to operate the EUT and monitor its status through separate equipment outside the anechoic chamber. External equipment operates and monitors the EUT through various communications such as 1553B communication, RS-485 communication, and Ethernet communication. At this time, external equipment can transmit noise through the communication line. This noise is transmitted to the LISN through the connected power cable and measured. It is also radiated through the connection terminal to the LISN. In this case, the communication line is the power line It should be designed so that noise is not transmitted through electromagnetic isolation as much as possible. In addition, noise from external equipment must be suppressed as much as possible from entering the chamber through the communication line. In this paper, external EUT test equipment applied for EMC test It explains the considerations in the design and manufacture of the design and explains the satisfaction of the design through tests including CE and RE.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.185-190
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• 2023

Recently, tracking radar requires the development of millimeter wave tracking radar to acquire target information with high resolution in various environments. The development of millimeter wave tracking radar requires the development of transmission and receiving components that can be applied to the millimeter wave tracking radar, as well as verification of the applicability of the tracking radar. In order to verify the applicability of the developed transmitting and receiving components, it is necessary to develop a signal acquisition device that can control the transmitting and receiving components using the operating concept of a tracking radar and check the status of the received signal. In this paper, we implemented a signal acquisition device that can confirm the applicability of components developed for millimeter wave tracking radar. The signal acquisition device was designed to process in real time the OOOMHz center frequency and OOMHz bandwidth signals input from 4 channels to verify the received signal. In addition, component control applying the tracking radar operation concept was designed to be controlled by communication such as RS422, RS232, and SPI and generation of control signals for the transmission and receiving time. Lastly, the implemented signal acquisition device was verified through a signal acquisition device performance test.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.223-228
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• 2010

High-frequency bottom loss measurements for grazing angle of $82^{\circ}$ in frequency range 17-40 kHz were made in Jinhae bay in the southern part of Korea. Observations of bottom loss showed the strong variation as a function of frequency, which were compared to the predicted values using two-layered sediment reflection model. The geoacoustic parameters including sound speed, density and attenuation coefficient for the second sediment layer were predicted from the empirical relations with the mean grain size obtained from sediment core analysis. The geoacoustic parameters for the surficial sediment layer were inverted using Monte Carlo inversion algorithm. A sensitivity study for the geoacoustic parameters showed that the thickness of surficial sediment layer was most sensitive to the variation of the bottom loss.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.1-10
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• 2024

In a previous study, a structure of a superplastic yoke consisting of a thin FR4 layer laminated with viscoelastic tape on both sides of a shape memory alloy (SMA) was proposed to reduce residual vibration generated by a deployable solar panel during high motion of a satellite. Damping properties of viscoelastic tapes will change with temperature, which can directly affect vibration reduction performance of the yoke. To check damping performance of the yoke at different temperatures, free damping tests were performed under various temperature conditions to identify the temperature range where the damping performance was maximized. Based on above temperature test results, this paper predicts temperature of the yoke through orbital thermal analysis so that the yoke can have effective damping performance even if it is exposed to an orbital thermal environment. In addition, the thermal design method was described so that the yoke could have optimal vibration reduction performance.