• Journal of IKEEE
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• v.24 no.1
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• pp.360-363
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• 2020

We present the power of the correlated superposition coding (SC) in non-orthogonal multiple access (NOMA). This paper derives closed-form expressions for the total allocated power with the constant total transmitted power. It is shown that the total allocated power is the function of a correlation coefficient. In result, the correlated SC NOMA should be designed with consideration of the correlation coefficient.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.349-358
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• 2007

Ethernet Passive Optical Network(EPON), which is one of PON technologies for realizing FTTx(Fiber-To-The-Curb/Home/Office), can cost-effectively construct optical access networks. In addition, EPON can provide high transmission rate up to 10Gbps and it is compatible with existing customer devices equipped with Ethernet card. To effectively control frame transmission from ONUs to OLT EPON can use Multi-Point Control Protocol(MPCP) with additional control functions in addition to Media Access Control(MAC) protocol function. For EPON, many researches on intra- and inter-ONU scheduling algorithms have been performed. Among the inter-ONU scheduling algorithms, IPS(Interleaved Polling with Stop) based on polling scheme is efficient because OLT assigns available time portion to each ONU given the request information from all ONUs. Since the IPS needs an idle time period on uplink between two consecutive frame transmission periods, it wastes time without frame transmissions. In this paper, we propose a dynamic bandwidth allocation algorithm to increase the channel utilization on uplink and evaluate its performance using simulations. The simulation results show that the proposed Two-phase Cycle Danamic Bandwidth Allocation(TCDBA) algorithm improves the throughput about 15%, compared with the IPS and Fast Gate Dynamic Bandwidth Allocation(FGDBA). Also, the average transmission time of the proposed algorithm is lower than those of other schemes.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.17-24
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• 2017

In recent digital broadcasting, up to 250 channels are multiplexed and transmitted. The channel transmission is made in the form of MPEG-2 Transport Stream (TS) and transmits one channel (Video, Audio). In order to check if many broadcast channels are transmitted normally, in multi-channel multi-view system, ability of real-time monitoring is required. In order to monitor efficient multi-channel, a distributed system in which functions and load are distributed should be implemented. In the past, we used an inefficient system that gave all of the functionality to a piece of hardware, which limited the channel acceptance and required a lot of resources. In this paper, we implemented a distributed multi-view system which can reduce resources and monitor them economically through efficient function and load balancing. It is able to implement efficient system by taking charge of decoding, resizing and encoding function in specific server and viewer function in separate server. Through this system, the system was stabilized, the investment cost was reduced by 19.7%, and the wall monitor area was reduced by 52.6%. Experimental results show that efficient real-time channel monitoring for multi-channel digital broadcasting is possible.

• Journal of Ocean Engineering and Technology
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• v.27 no.5
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• pp.28-35
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• 2013

In this paper, a research on the composition of the nesting algorithm fitness function is carried out by performing various numerical experiments to inspect how it affects the scrap efficiency, allocation characteristics, and time consumption, targeting the nesting results of ship parts. This paper specifically concentrates on a method to minimize the scrap ratio and efficiently use the well-defined remnants of a raw plate after the nesting process for the remnant nesting. Therefore, experiments for various ship parts are carried out with the weighting factor method, one of the multi-objective optimum design methods. Using various weighting factor sets, the nesting results are evaluated in accordance with the above purposes and compared with each set for each ship part groups. Consequently, it is suggested that the nesting algorithm fitness function should be constructed differently depending on the characteristics of the parts and the needs of the users.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.896-915
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• 2023

The network function virtualization (NFV) uses virtualization technology to separate software from hardware. One of the most important challenges of NFV is the resource management of virtual network functions (VNFs). According to the dynamic nature of NFV, the resource allocation of VNFs must be changed to adapt to the variations of incoming network traffic. However, the significant delay may be happened because of the reallocation of resources. In order to balance the performance between delay and quality of service, this paper firstly made a compromise between VNF migration and energy consumption. Then, the long short-term memory (LSTM) was utilized to forecast network traffic. Also, the asymmetric loss function for LSTM (LO-LSTM) was proposed to increase the predicted value to a certain extent. Finally, an experiment was conducted to evaluate the performance of LO-LSTM. The results demonstrated that the proposed LO-LSTM can not only reduce migration times, but also make the energy consumption increment within an acceptable range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8A
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• pp.1134-1143
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• 2000

We propose a scheduling algorithm, Bandwidth Allocation Scheme (BAS), that guarantees bounded delay in a switching node. It is based on the notion of the GPS (Generalized Processor Sharing) mechanism, which has clarified the concept of fair queueing with a fluid-flow hypothesis of traffic modeling. The main objective of this paper is to determine the session-level weights that define the GPS sewer. The way of introducing and derivation of the so-called system equation' implies the approach we take. With multiple classes of traffic, we define a set of service curves:one for each class. Constrained to the required profiles of individual service curves for delay satisfaction, the sets of weights are determined as a function of both the delay requirements and the traffic parameters. The schedulability test conditions, which are necessary to implement the call admission control, are also derived to ensure the proposed bandwidth allocation scheme' be able to support delay guarantees for all accepted classes of traffic. It is noticeable that the values of weights are tunable rather than fixed in accordance with the varying system status. This feature of adaptability is beneficial towards the enhanced efficiency of bandwidth sharing.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.47-70
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• 2008

The purpose of this study is to estimate total factor productivity(TFP) growth by stochastic frontier function and to grasp contributing factors of its growth rate by decomposing the total factor productivity into efficiency change, technical progress, scale change, and allocation change. Annual growth rate of total factor productivity for 1990-2003 is 0.019 (1.9%), higher than that of overall industry (0.010). The main component of TFP growth is not efficiency change but technical progress. Contributing factors of total factor productivity growth are change of allocation efficiency in port industry, technical progress in sea-transportation industry, and change of scale efficiency in transportation-equipment industry. The change of total factor productivity shows a decreasing trend since late in the 1990s. The annual technical efficiency of port-logistics industry is less than that of overall industry. Capital elasticity for output (0.391) is higher than labor elasticity (0.227), but scale economy of port-logistics industry is 0.618, which is far from optimal scale economy.

• Journal of the Korea Computer Industry Society
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• v.7 no.4
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• pp.299-308
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• 2006

Recently, A method of using the replicated database on a server to get new data without mis sing any information has been being studied in mobile computing environment. So far we ha ye used the Static Replica Allocation(SRA) for the replication which is the method of the replication on the server. This method is to replicate the data on the replica server after $\underline{a}$ moving host is transferred to a cell. Since the network of the SRA is very good, and if there are few moving users, no trouble will happen. But if there is no moving users in a cell, the data will not be shared. Therefore, this paper is about the study of the method of relocation after replicating the data to the cells for the users(User Select Replica Allocation : USRA). We also analyze the access rate and the possibility which are closely related to the moving frequency of the mobile hosts and the numbers of the cells. As a result, We show that the 5% lower access cost and the $2%\sim2.5%$ gains are achieved from the low mobility of the mobile hosts. We also show that t he extension function of USRA reduces the cost by 1.7% and it is influenced by the numbers of the cells.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.29-36
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• 2012

This paper includes ATP(Automatic Train Protection) simulator development and ATP algorithm verification to allocate wayside and train-borne and verify ATP functions of communications based train control system. The train control system has some characteristics such as simple structure and high safety when wireless communication technology is applied to the train control system. Especially, vital functions can be performed with in wayside and train-borne ATP. However, different system can be realized because I/F contents vary in accordance with vital functional allocation of ATP. Drawing characteristics in accordance with wayside and train-borne functional allocation and drawing I/F details affected by such characteristics are needed accordingly. This paper includes ATP simulator development creating train location information by direct activation of an electric motor, verifies train safety distance control algorithm of ATP by functional allocation such as train movement authority and train speed limit to ATP, and draws any supplementation needed. Appropriate simulated environment for verify ATP algorithm and main factors that affect to the ATP function were confirmed.

• Journal of Korea Port Economic Association
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• v.28 no.4
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• pp.257-274
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• 2012

Since service competition among global supply chains became intensified, market-oriented system, instead of the existing cost-based system, for port service pricing has been strongly recommended in order to enhance their long-term viability and competitiveness. The Owen value of cooperative game frameworks allows us to apply a market-oriented pricing theory for the port pricing in the case of Gwangyang port to verify its usefulness. The analytical results of this paper suggested some solutions in the problem of berth-based cost allocation by a characteristic function and also showed the proper relative weights of factors to derive the quay use index by Budescu(1993). We also suggested a favorable port pricing system to major shipping firms as well as a discount port pricing system for their strategic alliance. To put it differently, the results of this study enable the port managers to make out some strategic port pricing system like the reasonable discount in port charge for the larger ship owners using the ports frequently.