• Journal of Digital Contents Society
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• v.14 no.3
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• pp.349-356
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• 2013

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage and interference of Wi-Fi networks, and as a tradeoff between transmission power and data throughput, we propose a range-aware Wi-Fi network scheme which controls transmission power according to positions and RSSI(Received Signal Strength Indication) of Wi-Fi devices and analyze the efficiency of the proposed scheme by simulation.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1527-1534
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• 2010

The conventional peptide modification process of guanidination, in which the amino groups of lysine residues are converted to guanidino groups using O-methylisourea to create more basic homoarginine residues, is often used to improve the signal intensity of lysine-containing peptides in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Here, we used three different protease enzymes (trypsin, Lys-C, and Glu-C) to evaluate the effects of guanidination on the MS signals of two enzymatically digested proteins. Horse heart myoglobin and bovine serum albumin were guanidinated either before or after digestion with trypsin, Lys-C, or Glu-C. The resulting peptides were subjected to MALDI-MS, and signal intensities and sequence coverage were systematically evaluated for each digest. Guanidination prior to Glu-C digestion improved sequence coverage for both proteins. For myoglobin, guanidination before enzymatic digestion with trypsin or Lys-C also enhanced sequence coverage, but guanidination after enzymatic digestion enhanced sequence coverage only with Lys-C. For albumin, guanidination either before or after Glu-C digestion increased sequence coverage, whereas pre- or post-digestion guanidination decreased sequence coverage with trypsin and Lys-C. The amino acid composition of a protein appears to be the major factor determining whether guanidination will enhance its MALDI-MS sequence coverage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1521-1528
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• 2000

In this paper we analyze the performance of a DS/CDMA system in LEO mobile satellite channels. The channel uses the Extended Suzuki model which is the product of a Rician distribution having a LOS component and a lognormal distribution due to shadowing. We assume that the signal transmitted from the satellite to the mobile undergoes the same fading for the whole coverage of signal's beam. The average bit error probabilities of double coverage system is calculated in this paper. The interference resulting from the reference satellite is calculated for mobile located in the middle of the double coverage region whereas the additive interference from next-satellite is included for mobile located in the edge of the double coverage region. The performance of the mobile's receiving signal is dependent on shadowing and the interference of the next-satellite. We can obtain an obtain an improved average bit error probability by using dual diversity over the conventional correlated receiver for similar shadowing conditions in the coverage area of the satellite channel.

• Journal of the Korean Institute of Navigation
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• v.24 no.5
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• pp.405-415
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• 2000

DGPS/Radio beacons are currently being planned or installed in many countries. They offer a cost-effective way of distributing differential data to large number of users. These networks are also being deployed in South Korea, Japan, and China. Several DGPS stations among them are operating on the same frequencies. The DGPS signal based on a radio beacon in medium frequency band travels principally as a groundwave over the surface of the earth. The signal may also be received as skywaves at locations beyond about 100 km from the reference station. These skywaves interfere with groundwave signals due to fading. This factor has generally ignored in designing DGPS/Radio beacon systems. A further important factor is to reduce the coverage due to interference from other beacons on the same or adjacent frequencies. The desired signal may fade due to interaction between its skywave and groundwave components. It may degrade the accuracy of the positioning in a complex fashion. This paper estimates the coverage of Far East Asia DGPS stations which are operating on the same frequencies, which is based on the signal protection ratio and interference of the signal strength of the groundwave and skywave.

• Journal of Applied Reliability
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• v.8 no.2
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• pp.101-111
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• 2008

Good diagnostics improves both the safety and system unavailability of digital safety systems. The measure of a diagnostic capability is called the Coverage Factor. Because the Failure Modes, Effects and Diagnostic Analysis (FMEDA) provides information on the failure rates and failure mode distributions necessary to calculate a diagnostic coverage factor for a component, the FMEDA can be used as a useful tool to calculate it. Through performing FMEDA on a digital signal processor (DSP) board used in a digital safety system, it is shown that some components of the DSP board can be replaced or improved to satisfy the required diagnostic coverage. That is, the FMEDA can serve as a useful verification tool to design a diagnostic capability for the DSP board.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.17-23
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• 2012

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage, interference and network throughput by simulation on various network topology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.414-420
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• 2009

In this paper, we investigate throughput performance of OFDMA-based relay systems according to the "sub-cell coverage configuration" of the base station (RS) and the relay station (RS). RS is exploited for improved quality of the received signal with a tradeoff of additional radio resource consumption which may result in degradation of the throughput performance of the system. Therefore, "radio resource reuse" may be necessary for high performance in relay systems. However, it also causes system performance degradation since resource reuse between RSs incurs channel interference. Therefore, effective resource reuse also should be considered for "high throughput coverage configuration" when relays are employed. We relate the resource reuse patterns of neighboring RSs to sub-cell coverage configuration. We determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the mobile station (MS) from the BS and RS, respectively. Simulations illustrate the throughput performance as the function of SINR ratio, and it has different optimal point depending on the resource reuse patterns. Therefore, the "resource reuse pattern" and the "effective sub-cell coverage configuration" should be considered together for the high throughput performance of the relay system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.3
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• pp.226-232
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• 2002

This paper explains a technique to improve the fault coverage of oscillation-test [1-5] for linear analog circuits. The transient behavior of the virtual ground is monitored during oscillation to extract information of the circuit. The limitation of the oscillation-test is analyzed, and an efficient signature analysis technique is proposed to maximize the fault coverage. The experimental result proves that the parametric fault coverage can be significantly increased by the proposed technique.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.395-402
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• 2023

The implementation of a hybrid network utilizing Power Line Communication (PLC) and Wi-Fi technologies has been demonstrated to improve signal strength and coverage in areas with poor connectivity due to internet shadow areas. In this study we strategically positioned Wi-Fi relays and utilized the capabilities of PLC technology to significantly improve signal strength and coverage in areas with poor connectivity. We also analyzed the effects of metallic obstacles on Wi-Fi signal propagation and proposed a solution to strengthen the signal enough to pass through them. Our experiment demonstrated the feasibility and potential of using this hybrid network in industrial scenarios for real-time data transmission. Overall, the results suggest that the use of PLC and Wi-Fi hybrid networks can be a cost-effective and efficient solution for overcoming internet connectivity challenges and has the potential to provide high-speed internet access to areas with unreliable signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.231-236
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• 2016

The stability of DGPS signal in the DGPS service area was measured and the service availability according to the receiving signal strength was analyzed in this paper. Based on the effects of radio wave propagation in the seasons of winter and summer, daytime and night, the method to provide the DGPS service coverage was presented in this paper. The signal's strength of DGPS radio wave were measured at a constant distance from the DGPS reference station during a constant period. The propagation of DGPS radio wave is affected by status of ground conductivity, so the DGPS service area is dependant on the ground conductivity. To provide the stable service coverage, it is necessary to apply the adaptive power control for receiving signal's variations and the antenna design for alleviation of high elevation's radiation.