• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제8권5호
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• pp.431-441
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• 1997

In this paper, a performance evaluation method for the Trunked Land Mobile Radio System, so called TRS(Trunked Radio System), is presented. The proposed evaluation method employs LCD(Lost Call Delayed) system model and Erlang-C distribution. In this system, queues are used to hold call requests that are initally blocked. When a user attempts a call and a channel is not immediately available, the call request may be delayed until a channel becomes available. For evaluating system performance, therefore, the probability that any caller is delayed in the queue for a waiting time greater than t seconds is derived and simulated by using such parameters as total number of available channels, traffic load and average duration of a call. Furthermore, the performance of the message and the transmission trunked channel assignment strategies is compared. The performance simulation results show that transmission trunking is shown to be more efficient than message trunking.

• Journal of Navigation and Port Research
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• 제38권6호
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• pp.689-694
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• 2014

The Korean government has introduced and enforced maritime traffic safety assessment to secure traffic safety since 2010. The maritime traffic safety assessment is needed by law to design a new port or modify an existing one. According to Korea Maritime Safety Act, in the assessment the propriety of marine traffic system consists of the safety of channel transit and berthing/unberthing maneuver, safety of mooring, and safety of marine traffic flow. The safety of channel transit and berthing/unberthing maneuver can be evaluated only by ship-handling simulation. The ship-handling simulation is carried out by sea pilots working with the port concerned. The vessel's proximity measure is an important factor to evaluate traffic safety. The proximity measure is composed of vessel's closest distance to channel boundary and probability of grounding/collision. What is more, the probability of grounding becomes important. According to central limit theorem, a sample has a normal distribution on condition that its size is more than 30. However, more than 30 simulation runs bring about the increase of assessment period and difficulty of employing sea pilots. Therefore this paper is to find out minimum sample size for evaluating vessel's proximity. First sample sets of size of 3, 5, 7, 9 etc. are selected randomly on the basis of normal distribution. And then KS test for goodness of fit and t-test for confidence interval are applied to each sample set. Finally this paper decides the minimum sample size. As a result this paper suggests the minimum sample size of 5, that is, the simulation of more than five times.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.994-999
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• 1993

To service with high quality electricity to customer, the utilities consider the DAS (Distribution Automation System) as a good means of it. The backbone of the DAS are communication and computer technique. Most of all, from the economical and functional point of view, the selection of transmission media for system communication is the key factor to achieve a successful DAS. In this paper author propose the method of the DAS communication which share its channel with CATV transmission line and analyze the effect.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.219-225
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• 2000

Agricultural irrigation facilities are designed to storage, carriage, distribution and drainage water. Although those facilities may have different primary purposes, their technical functions are interrelated systematically. This Study aimed at developing the optimized object for integrated design for irrigation facilities. of reservoir and channel facilities, which are related by irrigation system design. So, total 17 elementary facility object was developed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.127-130
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• 2009

The uniform gas distribution between anode channels of the indirect internal reforming type molten carbonate fuel cell (MCFC) is crucial design parameter because of the electric performance and the durability problems. A three-dimensional computational fluid dynamics (CFD) analysis is performed to investigate flow characteristics in the anode channels and manifold under different pressure drop and channel temperature conditions. The combined meshes consists of hexadral meshes in the channels and polyhedral meshes in the manifold are adopted and chemical reactions inside the MCFC system are not included because of computational difficulties associated with the size and geometric complexity of the system. Results indicate that the uniformity in flow-rate is in the range of $\pm$ 0.048 % between the anode channels when the pressure drop of anode channel is about 150 Pa. A gas flow-rate uniformity decreases as the pressure drop of anode channels decreases and as the temperature difference between indirect internal reforming (IIR) channels and anode channels increases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.253-271
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• 2017

In this paper, considering that perfect channel state information (CSI) is hard to achieve in practice, the downlink capacity of distributed antenna systems (DAS) with imperfect CSI and multiple receive antennas is investigated over composite Rayleigh fading channel. According to the performance analysis, using the numerical calculation, the probability density function (PDF) of the effective output SNR is derived. With this PDF, accurate closed-form expressions of ergodic capacity and outage probability of DAS with imperfect CSI are, respectively, obtained, and they include the ones under perfect CSI as special cases. Besides, the outage capacity of DAS in the presence of imperfect CSI is also derived, and a Newton's method based practical iterative algorithm is proposed to find the accurate outage capacity. By utilizing the Gaussian distribution approximation, another approximate closed-form expression of outage capacity is also derived, and it may simplify the calculation of accurate outage capacity. These theoretical expressions can provide good performance evaluation for downlink DAS for both perfect and imperfect CSI. Simulation results verify the effectiveness of the theoretical analysis, and the system capacity can be improved by increasing the receive antennas, and decreasing the estimation error or path loss. Moreover, the system can tolerate the estimation error variance up to about 0.01 with a slight degradation in the capacity.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제2권3호
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• pp.309-315
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• 1998

This paper is analyzed the performance of coded MC-CDMA system using the multi-carrier with narrow band that is suggested to solve ISI and ICI of DS-CDMA system. In this paper, considered channel model is indoor mobile radio communication environment with Rician fading distribution and fading of multi-carrier have mutual independent characteristics. For the performance analysis of MC-CDMA system, first, bit error probability of uncoded system is simulated in the reverse and forward Rician channels. And then, it is simulated that bit error probability of coded MC-CDMA system for users, multicarriers and SNR, using (7,4) Hamming code, (15,7) BCH code and 1/2-convolutional code with 7 constraint length.

• Journal of Distribution Science
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• 제14권4호
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• pp.5-11
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• 2016

Purpose - The Education Ministry has plans to select top 10 percent academic journals among the domestic registration journals in NRF(National Research Foundation of Korea), and designate them as outstanding academic journals. To reflect this trend, KODISA has set its sights on paper publication rate and citation index with pushing forward globalism. First, this study will arrange the process of globalism and the current state of paper submission, and propose the direction of improvement in academic journals through understanding the characteristics of each major field. Research design, data, and methodology - KODISA has preceeded in examining and publishing research papers related to distribution field through indirectly or stimulating academic advancement. KODISA covers the whole fields in social science as well as in business administration and economics that associated with distribution field not limiting only within the range of distribution field. That is, the new subject that contributes to the progress in distribution field with original research can be a priority criteria in KODISA journal publication. Results - The major fields in papers published in KODISA can be categorized broadly as distribution field with economic and business administration point of view. Therefore, the distribution field with economic point of view includes the issues such as regulations, system, industry, market environment, distribution system, trade, and macroeconomics, etc. The business administration point of view in distribution includes distribution strategy, distribution organization, and distribution channel from the perspectives of the firm, etc. Conclusions - The aim of KODISA in 2020 is to be a global academic journal as SCI level of each journal in KODISA, JDS(Registration journal), IJIDB(Registration candidate), EAJBM(Registration candidate), JAFEB(Cabell's Registration journal). The KODISA journals have already settled as the largest academic society and journals of Korea in 2016 currently from humanities and social sciences area by the most gross in publication circulation, volumes, and types. Hereafter, KODISA will focus on the improvement for the objective indicators such as Impact Factor and Centrality index as qualitative growth as well as quantitative expansion. By doing so, KODISA will be a forum for developmental academic debate with attracting the world's greatest scholars' papers. Furthermore, they will be recognized journals and grow as the first-rate academic journals inside and outside of Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.86-89
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• 2009

In this paper, a broadband power line communication modem and network technology to develop tests with actual characteristics of the underground power line communication channel to be interpreted. Length and structure of the underground distribution line due to underground distribution line to the broadband powerline communication channels to measure the amount of attenuation on the signal generator, spectrum analyzer, such as contactless coupler was used to configure the channel measurement system. Demonstration tests in the test line as a single line by selecting the longest high-voltage lines where the two-channel measurement and signal attenuation on the noise level was measured. Measuring results degrade communication performance can be quite sure that was the presence of impulse noise, long lines, the line length was confirmed by the high-frequency attenuation appears.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• 제22권4호
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• pp.59-65
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• 2022

In this paper, a digital active phased array antenna is briefly introduced and beam forming method for a dual-channel side-lobe blanking applied to blank the side-lobe of the main beam is described. Next, the antenna performance was verified from results of design and antenna near-field measurement for the antenna main beam and side-lobe blanking beam. Then, a single-channel side-lobe blanking beam forming method was proposed to reduce the number of channels than the existing system operating dual-channel side-lobe blanking beam and weight distribution for each element of the side-lobe blanking antenna was designed with the proposed method. Finally, the designed single-channel side-lobe blanking beam pattern and blanking ability were verified and compared with the dual-channel side-lobe blanking beam. In addition, by comparing/verifying the conventional dual-channel and the proposed single-channel side-lobe blanking beam patterns measured through the receiving near-field test of the digital active phased array antenna and their ability to blank side-lobe of the main beam, validity of the proposed method for forming single-channel side-lobe blanking beam was confirmed.