• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.95-102
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• 2022

This paper proposed a linear time algorithm for a three-partition problem(TPP) in which a polynomial time algorithm is not known as NP-complete. This paper proposes a backtracking method that improves the problems of not being able to obtain a solution of the MM method using the sum of max-min values and third numbers, which are known polynomial algorithms in the past. In addition, the problem of MM applying the backtracking method was improved. The proposed algorithm partition the descending ordered set S into three and assigned to the forward, backward, and best-fit allocation method with maximum margin, and found an optimal solution for 50.00%, which is 5 out of 10 data in initial allocation phase. The remaining five data also showed performance to find the optimal solution by exchanging numbers between surplus boxes and shortage boxes at least once and up to seven times. The proposed algorithm that performs simple allocation and exchange optimization with less O(k) linear time performance complexity than the three-partition m=n/3 data, and it was shown that there could be a polynomial time algorithm in which TPP is a P-problem, not NP-complete.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.130-137
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• 2013

In this paper, we consider a two-agent scheduling with sequence-dependent exponential learning effects consideration, where two agents A and B have to share a single machine for processing their jobs. The objective function for agent A is to minimize the total completion time of jobs for agent A subject to a given upper bound on the objective function of agent B, representing the makespan of jobs for agent B. By assuming that the learning ratios for all jobs are the same, we suggest an enumeration-based backward allocation scheduling for finding an optimal solution and exemplify it by using a small numerical example. This problem has various applications in production systems as well as in operations management.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.658-669
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• 2016

The tremendous increase in mobile data traffic coupled with fierce competition in wireless industry brings about spectrum scarcity and bandwidth fragmentation. This inevitably results in asymmetric-valued long term evolution (LTE) spectrum allocation that stems from different timing for twice improvement in capacity between competing operators, given spectrum allocations today. This motivates us to study the economic effects of asymmetric-valued LTE spectrum allocation. In this paper, we formulate the interactions between operators and users as a hierarchical dynamic game framework, where two spiteful operators simultaneously make spectrum acquisition decisions in the upper-level first-price sealed-bid auction game, and dynamic pricing decisions in the lower-level differential game, taking into account user subscription dynamics. Using backward induction, we derive the equilibrium of the entire game under mild conditions. Through analytical and numerical results, we verify our studies by comparing the latest result of LTE spectrum auction in South Korea, which serves as the benchmark of asymmetric-valued LTE spectrum auction designs.

• Journal of KIISE
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• v.44 no.8
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• pp.854-859
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• 2017

Caching popular videos in the storage of base stations is an efficient method to reduce the transmission latency. This paper proposes an incentive proactive cache mechanism in the wireless network to motivate the content providers (CPs) to participate in the caching procedure. The system consists of one/many Infrastructure Provider (InP) and many CPs. The InP aims to define the price it charges the CPs to maximize its revenue while the CPs compete to determine the number of files they cache at the InP's base stations (BSs). We conceive this system within the framework of Stackelberg game where InP is considered as the leader and CPs are the followers. By using backward induction, we show closed form of the amount of cache space that each CP renting on each base station and then solve the optimization problem to calculate the price that InP leases each CP. This is different from the existing works in that we consider the non-uniform pricing scheme. The numerical results show that InP's profit in the proposed scheme is higher than in the uniform pricing.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.68-75
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• 2004

In this paper, n study a distributed establishment scheme to setup lightpath in WDM/TDM Network considering user traffic characteristics. We propose a GBTA(guaranteed-bandwidth time-slot allocation) algorithm which assigns time-slots according to the requred traffic so that it can utilize given network resources efficiently in RWTA(routing and wavelength time-slot assignment) schemes. We consider traffic specification on the basis of ATM traffic classes. Also, in order to increase link utilization and minimize blocking probability, we extend distributed lightpath establishment protocol based on GBTA algorithm. In order to establish lightpath in distributed WDM/IDM network, we use backward resonation protocol that resewes resource with recent information. We use DOWTns(Distributed Optical WDM/TDM ns) that is extended from NS(Network Simulator), in order to verify proposed GBTA-based optical wavelength routed network.

• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.46-54
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• 2006

We propose an optimization method for PCB assembly lines including multiple surface mounters. To increase the productivity of PCB assembly line, the component allocation, feeder assignment, and assembly sequence of each surface mounter should be optimized. The optimization Problem is formulated as an integer programming problem. We divide the overall problem into two hierarchical sub-problems: forward-path problem and backward-path problem. The clustering algorithm and branch-and-bound algorithm are applied to solve the forward-path problem. The assignment algorithm and connection algorithm are applied to solve the backward-path problem. Simulation results are presented to verify the usefulness of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.9
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• pp.4166-4182
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• 2018

We consider the Device-to-Device (D2D) communications in cellular networks where each cellular user (CU) shares the same resource with multiple D2D users (DUs). In this paper, we aim to maximize the energy efficiency (EE) of the D2D networks, subject to an interference constraint required by the CU. Since the cellular and D2D communications belong to different networks, we consider to incentivize base station (BS) while assisting the DUs. To this end, we propose a Stackelberg game based interference pricing framework for the considered D2D communications in cellular networks. Unlike most of the existing methods, we use interference pricing framework to jointly address the EE resource allocation problem and the interference management in our networks rather than only improve the EE of the DUs or protect cellular networks. In particular, BS and all the users do not need all channel state information, which is more realistic in practice. In addition, two different pricing strategies are also proposed. Based on the two strategies, we analyze the equilibrium of the game. Moreover, in the first strategy, the upper and lower boundaries of the interference price are obtained. The closed-form expression is gained with a backward induction for the second strategy. Both offer valuable insights to the considered scenarios. Finally, compared with the existing work, the EE of the D2D communications is significantly improved. The advantageous performance of our scheme are demonstrated by the simulation results.

• Korean Journal of Applied Biomechanics
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• v.14 no.2
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• pp.27-40
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• 2004

The objective of this study is to identify the kinematic variables of giant swing backward to handstand as well as individual variations of each athlete performing this skill, which in turn will provide the basis for developing suitable training methods and for improving athlete's performance in actual games. For this end, 3 male athletes, members of the national team, who are in ${\Box}{\Box}H{\Box}{\Box}$ University, have been randomly chosen and their giant swing backward to handstand performance was recorded using two digital cameras and analyzed in 3 dimensional graphics. This study came to the following conclusion. 1. Proper time allocation for giant swing backward to handstand are: Phase 1 should provide enough time to attain energy for swing track of a grand round movement. The phase 3 is to throw the body up high in the air and stay in the air as long as possible to smoothen up the transition to the next stage and the phase 4 should be kept short with the moment arm coefficient of the body reduced. 2. As for appropriate changes of locations of body center, the phase 1 should be comprised of horizontal, perpendicular, compositional to make up a big rotational radius. Up to the Phase 3 the changes of displacements of vertical locations should be a good scale and athlete's body should go up high quickly to increase the perpendicular climbing power 3. When it comes to the speed changes of body center, the vertical and horizontal speed should be spurred by the reaction of the body in Phase 2 and Phase 3. In the Phase 4, fast vertical speed throws the body center up high to ensure enough time for in-the-air movement. 4. The changes of angles of body center are: in Phase 2, shoulder joint is stretching and coxa should be curved up to utilize the body reaction. In the Phase 4, shoulder joint and coxa should be stretched out to get the body center as high as possible in the air for stable landing. 5. The speeds of changes in joints angles are: in the Phase 2 should have the speed of angles of shoulder joints increase to get the body up in the air as quickly as possible. The Phase 3 should have the speed of angles in shoulder joint slow down, while putting the angles of a knee joint up to speed as quickly as possible to ensure enough time for in-the-air movement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.360-370
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• 2010

In this paper, a distributed beamforming problem is considered in an amplify-and-forward (AF) wireless relay network consist of multiple source-destination pairs and relaying nodes. To exploit degree of freedom of the number of beamformers, in the first step, we proposed that the sources transmit their signals through orthogonal channels. During the second step, the relays transmit their received signals multiplied by complex weights to amplify and compensate for phase changes introduced by the backward channels through one common channel. The optimal beamforming vectors are obtained through minimization of the total relay transmit power while the signal-to-interference-plus-noise ratios (SINRs) at the destinations are above certain thresholds to meet a quality of services (QoSs) level. In the numerical example, it is shown that the proposed scheme needs less transmit power for moderate network data rates than other schemes, such as space division multiplexing or time-division multiplexing scheme.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.1
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• pp.81-91
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• 2007

The European Union(EU) has implemented the Structural Funds since 1994, in order to achieve its harmonious development though the strengthening of economic and social cohesion in the EU territory, and particularly to tackle regional disparities and to support backward regions in the territory. In the July of 2006, the Council of EU has flatly laid down the provisions of the Structural Funds which is applied to the period of 2007-2013, having regard to the proposal from the European Commission and the assent of the European Parliament. Given this context, this work deals with the features of the Structural Funds(2007-2013), focusing on the funds' objectives, the regions and countries under the application of such objectives, allocation of the funds among the EU Member States, and the funds' financial resources.