• ETRI Journal
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• v.30 no.1
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• pp.164-166
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• 2008

This paper proposes a priority-based duplicate burst transmission mechanism in an optical burst switching network to enhance the probability of successful reception of bursts. The performance of the proposed mechanism is evaluated by NS2 simulations. Our results show that the burst loss rate is improved especially under light traffic loads.

• Convergence Security Journal
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• v.14 no.7
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• pp.29-36
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• 2014

In this study, we design and develop a VLC test-bed system which has been recently issued and focused as good convergence technology in the world. We classify the developed system into transmission part including analog LED driver module, digital signal modulation module, and receiver part with light sensing module and signal demodulation module. Then we introduce important characteristics and components. We analyze some factors for each module. To validate the communication of the designed VLC system, we develop a VLC sender-receiver simulator which can control the dimming factor and flicker-free effect. From the developed system, we observed about 12Mbps of data transmission rate with 0.5m~1m of distance, without packet loss. We verified the real-time communication with multimedia streaming which can be considered as very high date rate. The developed system and technology will be useful for some converged data services like indoor positing, home appliances, and indoor parking system.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.41-46
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• 2014

In this paper, a transceiver of VLC (Visible Light Communication) using LED white lighting has been implemented. We analyzed differences between conventional wireless communication and VLC with high-speed data transmission in a variety of environments, and confirmed symbols which passed through a channel using QAM. In order to get a high data rate, we found some variables that should be considered essentially though experiments. In addition, we set a bandwidth and found an optimal gain according to the distance between transmitter and receiver. We analyzed proposed system model through Labview and finally showed a system performance. The performance showed a 2Mbps QAM data rate in real visible light indoor channels.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.277-283
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• 2016

Background: The photosynthetic efficiency cool-season, semi-shade ginseng is normal at low morning temperatures, but drops at high afternoon temperatures. Therefore, optimal plant performance would be ensured if it were possible to control daily light transmission rates (LTR). Methods and Results: Plants were grown in a controlled light environment that replicated 11 AM conditions and comparatively analyzed against plant grown under normal conditions. Growth in the controlled light environment resulted in a 2.81 fold increase in photosynthetic efficiency with no change in chlorophyll content, although LTR were high due to low morning temperatures. Increased aerial plant growth was observed in the ginseng plants adapted to the controlled light environment, which in turn influenced root weight. An 81% increase in fresh root weight (33.3 g per plant on average) was observed in 4-year-old ginseng plants grown in controlled light environment compared to the plants grown following conventional practices (18.4 g per plant on average). With regard to the inorganic composition of leaves of 4-year-old ginseng plants grown in controlled light environment, an increased in Fe content was observed, while Mn and Zn content decreased, and total ginsenoside content of roots increased 2.37 fold. Conclusions: Growth of ginseng under a favorable light environment, such as the condition which exist naturally at 11 AM and are suitable for the plant's photosynthetic activity creates the possibility of large scale production, excellent-quality ginseng.

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.3-10
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• 1981

In order to analyze growth and yield of rice population at the stand point of productive ecology, productive structure and growth rate of rice plants and effects of their related factors were studied. The results obtained were summarized as follows: 1. High crop growth rate was maintained throughout growing season when rice plants grew in population compared to a single rice plant. Since crop growth rate in rice stands were also higher at ripening stage, higher yields were obtained. 2. Higher crop growth rate of rice plants in population was maintained by the increase of leaf area rather than by net assimilation rate. 3. As the overgrowth of upper leaves of plant population in some rice varieties transmission of light into lower leaves was inhibited and thus most of them were eventually died before flowering. 4. In the case of rice population, the ratio of productive organ to non-productive organ, light transmission rate and nitrogen contents of active leaf blade were lower than individual rice plants under isolated condition.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.770-781
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• 2016

As a result of reducing color information and edge information, object distinction in haze image occurs with difficulty. One of the famous defogging algorithm is haze removal by using 'Dark Channel Prior(DCP)', which is used to predict for transmission rate using color information of an image and eliminates haze from the image. But, In case that haze rate is estimated under color information, there is a miscalculated issue which is posed by haze rate and transmission in area with high brightness such as a white object or a light source. In this paper, We deal with a miscalculated issue by correcting from around haze rate, after application of color normalization used by main white part of image haze. Moreover, We calculation improved transmission based on the result of improved haze rate estimation. And then haze image quality is developed through refining transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10C
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• pp.992-998
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• 2005

In this paper, An Ultra Fast Acquisition Algorithm of low transmission rate ultra-wideband(UWB) systems for car positioning and traffic light controling is proposed. Since the acquisition algorithms for CDMA system are not fast enough to access the low transmission rate UWB systems, the new ultra fast acquisition scheme which can be implemented with low cost and simplified circuit is required. The proposed algorithm adopted the Recurrent Sequential Estimation scheme and trinomial M-sequence. Therefore, The proposed scheme can reduce the average acquisition time in $1\~3{\mu}sec$ with simple circuit, even for the UWB systems which use long pseudo-noise(PN) sequence and transmit low power below the FCC EIRP emission limits. The simulation results for the average acquisition time of the proposed scheme are compared with the ones of the existing acquisition schemes.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.129-131
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• 1993

A transcutaneoos information transmission system using transmitted infrared light for an implantable total artificial heart(TAH) an developed and the performance of the system was tested. In an in vitro test, transmittance of the developed system was measured through various thicknesses of pig shins. In an in vivo test, a loopback test using a personal computer was performed to determine the error rate and an experiment using a mock system was taken. In this experiment, within acceptable lateral and vertical displacements, the error rate of at least 3.8E-6 was guaranteed. Monitoring signals from the internal controller(Intel 87C196) of the mock system were successfully transmitted to the external controller(IBM PC) and the operating commands from the external controller were successfully conducted by the mock system. Communication was done in half duplex mode according to RS-232 protocol at the speed of 4800 bps.

• ETRI Journal
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• v.29 no.6
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• pp.808-810
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• 2007

We demonstrate 10 Gbps optical signal transmission via long-range surface plasmon polaritons (LR-SPPs) in a very thin metal strip-guided geometry. The LR-SPP waveguide was fabricated as a 14 nm thick, 2.5 ${\mu}m$ wide, and 4 cm long gold strip embedded in a polymer and pigtailed with single-mode fibers. The total insertion loss of 16 dB was achieved at a wavelength of 1.55 ${\mu}m$ as a carrier wave. In a 10 Gbps optical signal transmission experiment, the LR-SPP waveguide exhibits an excellent eye opening and a 2.2 dB power penalty at $10^{-12}$ bit error rate. We confirm, for the first time, that LR-SPPs can efficiently transfer data signals as well as the carrier light.

• Journal of IKEEE
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• v.21 no.2
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• pp.115-122
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• 2017

In vehicular safety service, every vehicle broadcasts Basic Safety Message (BSM) periodically to inform neighbor vehicles of host vehicle information. However, this can cause network congestion in a region that is crowded with vehicles resulting in a reduction in the message delivery ratio and an increase in the end-to-end delay. Therefore, it could destabilize the vehicular safety service system. In this paper, in order to improve the congestion control and to consider the hidden node problem, we propose a congestion control scheme using entire network congestion level estimation combined with transmission power control, data rate control and time slot based transmission control algorithm. The performance of this scheme is evaluated using a Qualnet network simulator. The simulation result shows that our scheme mitigates network congestion in heavy traffic cases and enhances network capacity in light traffic cases, so that packet error rate is perfectly within 10% and entire network load level is maintained within 60~70%. Thus, it can be concluded that the proposed congestion control scheme has quite good performance.