• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.63-69
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• 2014

Visible light communication is a communication method using an LED's blinking(ON/OFF), it has a feature of light because of the limit of perception by the human's optic nerve. LED' dimming control used in the VLC system is important factor needed to provide energy saving and life benefits. With advances in VLC system, MIMO technology has received much attention in that it can be obtain channel capacity proportionate to the number of antenna. Therefore, in this paper, with RC method which is one of the MIMO style in VLC system, it is compared communication performance using RZ-OOK, VPPM, MPPM and OPPM. As a result of the simulation was run against this, MPPM works well in terms of Power requirement and OPPM works well in terms of Spectral efficiency and Bandwidth requirement, also it was confirmed that there is a significant impact on the communication performance of each modulation scheme according to the dimming.

• Journal of Communications and Networks
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• v.7 no.4
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• pp.462-470
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• 2005

We propose a multi-rate and multi-BEP transmission scheme using adaptive overlapping pulse-position modulator (OPPM) and optical power controller in optical code division multiple access (CDMA) networks. The proposed system achieves the multi-rate and multi-BEP transmission by accommodating users with different values of OPPM parameter and transmitted power in the same network. The proposed scheme has advantages that the system is not required to change the code length and number of weight depending on the required bit rate of a user and the difference of bit rates does not have so much effect on the bit error probabilities (BEPs). Moreover, the difference of transmitted powers does not cause the change of bit rate. We analyze the BEPs of the four multimedia service classes corresponding to the com­binations of high/low-rates and low/high-BEPs and show that the proposed scheme can easily achieve distinct differentiation of the service classes with the simple system configuration.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.71-78
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• 2017

Visible light communication (VLC) offers communication function in addition to illumination. Because the signal communication capacity per cable is 1,000 times compared to the power line communication (PLC), optical fiber is being advertised as the basis of the information and communication. Also dimming control of LED is an important component needed to provide energy savings and quality of life. This study configured multi-hop VLC system model in a building using optical fiber and analyzed the power performance of two of modulations using dimming techniques. The transmission power and received power were used to compare the power performance in multi-hop VLC environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.169-180
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• 2018

White light-emitting diodes (LEDs) are more economical than fluorescent lights, and provide high brightness, a high lifetime expectancy, and greater durability. As LEDs are closely connected with people's daily lives, dimming control of LED is an important component in providing energy savings and improving quality of life. In visible light communications systems using these LEDs, multiple input multiple output (MIMO) technology has attracted a lot of attention, in that it can attain the channel capacity in proportion to the number of antennas. This paper analyzes the power performance of three kinds of modulation in visible light communications (VLC) systems applied space-time block code (STBC) techniques. The modulation schemes are return-to-zero on-off keying (RZ-OOK), variable pulse position modulation (VPPM), and overlapping pulse position modulation (OPPM), and dimming control was applied. The power requirements and power consumption were used as metrics to compare the power efficiency in $2{\times}2$ STBC-VLC environments under the three kinds of modulation. We confirm that dimming control affects the communications performance of each modulation scheme. VPPM showed greater consumption among the three modulations, and OPPM showed energy savings comparable to VPPM.

• Asian Journal of Turfgrass Science
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• v.10 no.4
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• pp.315-329
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• 1996

The changes of growth and protein synthesis pattern by aluminum (Al), cadmium (Cd), zinc (Zn) treatments were studied in Cyanobacterium synechocystis sp. PCC 6803. When exposed to Al from 5ppm to 3oppm, synechocystis grows normally. But more than that retard the growth of algae notably. The 0.05ppm Cd additions had no effect on the growth of algae. 0.1, 0.2, and 0.5ppm Cd inhibited growth. Under 1 and 2ppm Cd stress, growth was greatly diminished. Zn had dual effects. The growth of algae in media containing 5ppm was stimulated. As concentration increases more than l5ppm, growth inbition increases. Under 25ppm Zn stress, growth was greatly diminished. According to logistic theory, r and K values of each heavy metal-treated groups were estimated. Correlation analysis of r and K values with metal concentration shows that there is negative correlation between K and concentration in Cd and Zn treatments. Critical concentration which shows lethal or sublethal effect was estimated by t-test of each r and K value. The cells cultured in 10, 20, 30, 40 and 5oppm of Al, 1 and 2ppm of Cd, and 10, 15, 20, 25 and 30ppm of Zn for 4 days was used for protein analysis. Analysis of protein synthesis with SDS-PACE showed alterations of protein synthesis pattern. The synthesis of protein about 220kD increased markedly. In this study, it showed that resistance mechanism against Al, Cd, and Zn is K selection and that metal stress induced the change of protein synthesis in Cyanobacterium synechocystis sp. PCC 6803.Key words:Cyanobacterium synechocystis sp. FCC 6803, Heavy metals, Aluminum, Cadmiutm Zinc, Crowth, Frotein synthesis.

• Korean Journal of Plant Resources
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• v.1 no.1
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• pp.88-92
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• 1988

The study was conducted to determine the optimal basal media and the concentration of plant growth regulator for germination of seeds and growth of plantlet from Dendrobium monile. The results obtained were summarized as follows. Germination was similar in light and dark condition, but the growth of plantlet after germination was better under dark than under light condition in several media. Germination was best in Hyponex and Kyoto solution medium among the 9 media tested. The number of roots/shoot was most in the Hyponex medium containing 0,1ppm NAA and 1.Oppm BA.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.2
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• pp.65-74
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• 1996

This study was carried out to investigate the water quality of agricutural reservoirs in Chonbuk Province. The water quality of 189 agricultural reservoirs was surveyed in the environmental standard phase of pH, EC, DO, BOD, COD, T-N, T-P, etc. The results obtained in this study are summarized as follows ; 1. The levels of mean reservoir storage were very low as 26.9% in January and February, 29.4% in June, 16.0% in August, and 25.4% as a whole. 2. The water qualities of agricultural reservoirs were shown to be in the average of 6.8in pH, 0.2l0mmhos/cm in EC, 49.Oppm in turbidity, 28.5mg/$\ell$in SS, 3.79mg/$\ell$ in DO, 9. 9mg/$\ell$ in COD, 5.Smg/$\ell$ in BOD, 0.179mg/ $\ell$ in T-P, 4.O9mg/$\ell$ in T-N, 0.416meq/$\ell$ in Na, 0.154meq/$\ell$ in K, 0.320meq/$\ell$ in Ca, 0.166meq/$\ell$ in Mg, respectively. 3. In the analyzed results, the proper counterplan is desirable to be considered because the levels of water quality in most items except DO were comparatively higher than the limit points of agricultural water quality standard.

• KSBB Journal
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• v.8 no.2
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• pp.150-155
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• 1993

This study describes biodegradation of dyes which are used in textile industries. Dyes released into the environment from industrial waste water are considered to be a serious pollution problem because of the wide spread into environment with a variety of colors. The microorganisms used in this experiment were Pseudomonas species, which had been screened from aeration tank of waste water treatment. It was found that optimum concentrations for culture media were 14g of glucose, 6g of peptone, 160 mg of Na2HPO4, 200mg of KCl, 140mg of MgSO4,.7H2O,1.0g of KH2PO4, 400mg of NaCl, 200mg of CaCl2 and dye 10ppm per litre of distilled water. The high efficiency of dye degradation was obtained at pH 7-8 and $30-35^{\circ}C$. Strains screened are excellent for removal of azo and reactive dyes, which are relatively stable and difficult to degrade. Dyes of 10ppm such as mono-azo (Lot No. 180), di-azo (Lot No. 138) and reactive red(Lot No. 2) were mostly decolorlzed within 2 days and di-azo (Lot No. 151) and reactive red(Lot No. 34, No. 00166) were decolorized within 5 days in the controlled fermenter. In the case of reactive dyes, oxygen supplies showed lower biodegradability compared to anaerobic culture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1876-1882
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• 1999

In this paper, we have proposed a FCB detection algorithm for the GSM system which is european cellular standard. The detection algorithm can be implemented using received signal sampler, correlator, and post detection combiner. GSM mobile phone can use the proposed algorithm for detection of the Broadcasting Channel, and to obtain the initial timing estimate. The proposed algorithm has a architecture which is suitable for DSP or ASIC implementation, and required memory size is small. The performance of the algorithm is a function of the processing data window size and the threshold values. Proper window size and the threshold values can be determined by analyzing the correlator and combiner. The proposed algorithm has been implemented using DSP, and the performance was verified using baseband simulation. The simulation assumed frequency offset values of 0ppm and 15ppm with the receiver filter bandwidth set at both minimum and maximum. It is shown that the algorithm is robust under various assumptions, and suitable for real implementations.

• Membrane Journal
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• v.2 no.1
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• pp.21-32
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• 1992

Hydrogen-permselective silica membranes were synthesized within tim walls of porous Vycor tubes by chemical vapor depostion of $SiO_2$. Film deposition was carried out using $SiCl_4$ hydrolysis either in the oppm shag reactants or in the one-sided geometry. At temperatures above $600^{\circ}C$ the permeation rate of hydrogen thorough the silica films varied between 0.01 and $025cm^3(STP)/cm^2-min-atm$ depending on the reaction geometry and the $H_2 : N_2$ permeation ratio was about 1000. Permeation rates of both $H_2$ and $N_2$ increased with increasing temperature. The silica membranes produced by one-sided deposition have higher hydrogen permmeation rates than those produced by the opposing reactants geometry although the membranes formed in an opposing reactants geometry were relatively stable during the heat treatment or after exposure to ambient air. These membranes can be applied to high temperature gas separations or membrane reactors once the film deposition process is optimized to get high permeability as well as good stability.