• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.93-97
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• 2007

In this paper, centralized access control and slot allocation algorithm is proposed for wireless networks. The proposed algorithm is characterized by the contention-based reservation. In order to reduce the collision probability of reservation request, the base station calculates and broadcasts the transmission probability of reservation requests, and the wireless terminal transmits its reservation request with the received transmission probability. The scheduler allocates the uplink data slots based on the successful reservation requests. Simulation results show that the proposed algorithms can provide high channel utilization, and furthermore, maintains constant delay performance in the heavy traffic environment.

• Journal of Korean Vacuum Science & Technology
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• v.2 no.1
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• pp.1-8
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• 1998

The uniform distributed pumping model is used to derive analytic expressions of the pressure profile for the molecular flow regime in linearly tapered or flared(conical or pyramidal) tubes with wall sorption. The concept of transmission conductance for sticky tubes of arbitrary shape is newly introduced to calculate the transmission probability using the pressure profile. The transmission probability obtained analytically for a conical sticky tube is compared with that from the Monte Carlo simulation.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.677-681
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• 2010

This paper proposes a transmission probability control scheme for enhancing the performances of FSA-based RFID system. In order to maximize the system performance, the number of tags attempting to transmit their identifiers in a frame should be kept at a proper level. The reader calculates the transmission probability according to the number of tags within the identification range of reader and then broadcasts it to tags. Tags, in which their slot counter values reach to zero, attempt to transmit their identifiers with the received probability. Simulation results show that the proposed scheme can offer better throughput and delay performance than the conventional one regardless of the number of tags.

• Wind and Structures
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• v.10 no.1
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• pp.45-60
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• 2007

Transmission tower is a vital component in electrical system. In order to accurately compute the dynamic response and reliability of transmission tower under the excitation of wind loading, a new method termed as probability density evolution method (PDEM) is introduced in the paper. The PDEM had been proved to be of high accuracy and efficiency in most kinds of stochastic structural analysis. Consequently, it is very hopeful for the above needs to apply the PDEM in dynamic response of wind-excited transmission towers. Meanwhile, this paper explores the wind stochastic field from stochastic Fourier spectrum. Based on this new viewpoint, the basic random parameters of the wind stochastic field, the roughness length $z_0$ and the mean wind velocity at 10 m heigh $U_{10}$, as well as their probability density functions, are investigated. A latticed steel transmission tower subject to wind loading is studied in detail. It is shown that not only the statistic quantities of the dynamic response, but also the instantaneous PDF of the response and the time varying reliability can be worked out by the proposed method. The results demonstrate that the PDEM is feasible and efficient in the dynamic response and reliability analysis of wind-excited transmission towers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1784-1788
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• 2012

In this paper we considered condition for keep standard error probability in optical transmission system that applied on-off keying transmission which are modulated amplitude along the signal. we calculated received sensitivity of receiver in on-off keying transmission for optical detector have quantum efficiency belong 1 in optical transmission system. For BT is over 30, the number of photon is belong 10000 for maintain standard error probability. also we considered Also, we install a preamplifier to the receiver for considering the low output may be used with a light that was able to get results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3638-3654
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• 2014

Cognitive Radio (CR) users need to sense the environment or channel at regular time interval for sharing the spectrum band of the primary users (PUs). Once find the spectrum idle, CR users start their transmission through it. Even while transmitting, they need to continue the sensing process so that they can leave the spectrum immediately whenever find a PU wanting to use the band. Therefore, detecting PUs is one of the main functions of cognitive radio before transmission and higher the detection probability ensures better protection to the primary users. However, it is not possible to attain a high detection probability (or a low miss detection probability) and low false alarm probability simultaneously as there is a tradeoff between false alarm probability ($P_{fa}$) and the probability of detection ($P_d$). In this paper, the author has provided a comprehensive study on different sensing techniques and discussed their advantages and disadvantages. Moreover, it is expected that, with this article, readers can have a through understanding of sensing techniques in CR and the current research trends in this area.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.560-566
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• 2008

Today, as the power trades between generation companies and power customer are liberalized, the uncertainty level of operated power system is rapidly increased. Therefore, transmission operators as decision makers for transmission expansion are required to establish a deliberate investment plan for effective operations of transmission facilities considering forecasted conditions of power system. This paper proposes the methodology for the optimal solution of transmission expansion in deregulated power system. The paper obtains the expected value of transmission congestion cost for various scenarios by using occurrence probability. In addition, the paper assumes that increasing rates of loads are the probability distribution and indicates the location of expanded transmission line, the time for transmission expansion with the minimum cost for the future by performing the Montecarlo simulation. To minimize the investment risk as the variance of the congestion cost, Mean-Variance Markowitz portfolio theory is applied to the optimization model by the penalty factor of the variance. By the case study, the optimal solution for transmission expansion plan considering the feature of market participants is obtained.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.15-21
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• 2021

Losses of both life and property increased from damage to underground pipe such as heat transmission pipe buried underground in downtown because pipes are gradually aging. Considering the characteristics of the heat transmission pipe, which is not exposed to the outside and difficult to immediately identify problems such as damage, it is realistic to indirectly check the condition of the facility based on the historical information that is periodically collected through facility maintenance. In this study, a methodology for estimating the damage probability was developed by examining the history information of the heat transmission pipe, deriving an evaluation factor that is related to the damage probability. The contribution factor of the damage probability were reviewed by analyzing not only the guidelines for maintenance of heat transmission pipe of advanced European countries and domestic district heating companies, but also the cases of waterworks with similar characteristics. Evaluation factors were selected by considering not only the correlation with the damage probability but also the possibility of securing data. Based on 1999, when the construction technology and standards of heat transmission pipe changed, the damage probability estimation function according to the period of use was divided into the case of being buried before 1998 and the case of being buried after 1999, and presented. In addition, the damage probability was corrected by assigning weights according to the measured data for each evaluation factor such as the diameter, use, and management authority.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.25-32
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• 2010

This paper evaluates the outage probability of cognitive relay networks with cooperation between secondary users based on the underlay approach, when multiple primary receivers coexist with secondary users. Using an appropriate relay selection criterion in cognitive radio networks, we derive the outage probability of secondary user. It is shown that the outage probability increases as the number of primary receivers increases and we quantify the increase. Through the simulation results, we verify that the performance of relaying transmission is varied more sensitively compared to that of direct transmission as the number of primary receivers increases. In addition, the relaying transmission can be less efficient than the direct transmission when multiple primary receiver exist but it can be more efficient than the direct transmission by increasing the relay selection diversity.

• Journal of Korea Multimedia Society
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• v.19 no.3
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• pp.620-625
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• 2016

In this paper, we offer the secrecy outage probability of the amplify-and-forward (AF) transmission, which consists of one source, one destination, one relay, and one passive eavesdropper. Particularly, we consider that the relay is equipped with multiple antennas while other terminals is utilized with single antenna and apply diversity techniques (for both the reception and the transmission) at the relay to achieve gains in a secrecy outage performance. Additionally, we analyze the exact secrecy outage probability of the proposed systems in a one-integral form. Finally, some numerical examples are given to verify our provided analytical results for different system conditions.