• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.7
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• pp.2862-2878
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• 2020

Data Security is the most challenging area in Internet communication, where most of the secret sharing schemes are proposed for binary images. But still it lacks in providing security for data communication, especially in image transmission. Traditional visual cryptography scheme generate meaningless diwies and the reconstruction phase leads to quality degradation over the secret image. In this work, an intelligent two dimensional secret share construction scheme is proposed. A secret image is expanded into n diwies with the choice of scheme selection. By Stacking all the qualified diwies to revert the secret image without content loss and less than s^* - 1 shares could not reveal any information about the secret image. The experimental results emphasize that the proposed secret share scheme is highly secured for image transmission.

• Journal of Korea Game Society
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• v.1 no.1
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• pp.31-36
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• 2001

Generally, the internet online game systems are divided into two parts, clients and servers. The clients provide a connection with game server to each user and communicate between them. And, the server controls all clients by the game rules fairly and manages database systems to maintain the user information. In this paper, we propose a configuration method for internet online game servers using distributed scheme. To apply this method, we divide game server into three sub-level parts again. First part of game server is login server to establish the connection between communication server and clients. Second part is communication server to connect between clients and main game server during playing the game. And last part is DBMS that performs database independently. Our proposed scheme suggests that the game server operates very stable because of decreasing of processing load by distributed scheme. So, our proposed server configuration applies to similar online game easily.

• Journal of information and communication convergence engineering
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• v.13 no.2
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• pp.86-96
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• 2015

In mobile communication, mobile services [MSs] (e.g., phone calls, short/multimedia messages, and Internet data) incur a cost to both mobile users (MUs) and mobile service providers (MSPs). The proposed model MobPrice consists of dynamic data pricing schemes for mobile communication in order to achieve optimal usage of MSs at minimal prices. MobPrice inspires MUs to subscribe MSs with flexibility of data sharing and intra-peer exchanges, thereby reducing overall cost. The main contributions of MobPrice are three-fold. First, it proposes a novel k-level data-pricing (kDP) scheme for MSs. Second, it extends the kDP scheme with the notion of service-sharing-based pricing schemes to a collaborative peer-to-peer data-pricing (pDP) scheme and a cluster-based data-pricing (cDP) scheme to incorporate the notion of 'cluster' (made up of two or more MUs) in mobile communication. Third, our performance study shows that the proposed schemes are indeed effective in maximizing MS subscriptions and minimizing MS's price/user.

• Korean Institute of Interior Design Journal
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• v.15 no.1 s.54
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• pp.147-157
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• 2006

The purpose of this study is to fond out the characteristics of color perception and preferred color scheme of the aged who becomes color weak due to yellowed eye sight. For this, this study was composed of two steps. First, an experimental simulation on aged vision using Spectrophotometer(CM-2600d, Minolta) attached Y-2 filter as a quasi lenses of the aged eye. The color data of 120 color chips of the aged vision was measured and analyzed to grasp the characteristics of color perception of the age. Then, a questionnaire survey was carried out with color chips and 8 interior color schemes. They participated in a questionnaire survey of the level of identification among the color chips of 11 tones of R, G, PB, as well as a survey of the preference color schemes. The result of this study are as follow; 1) The range of color perception on hue narrowed into YR, Y, GY, G. Especially, the aged have failed perception of B${\cdot}$PB${\cdot}$P${\cdot}$RP(short wave length of light) by yellowed eye sight. 2) The level of identification among the color chips of 11 tones of R,G,PB are different by each color. But Very Pale, Pale, Strong, Vivid are fractionated similarly in almost color. 3) In the preference of interior color scheme of the aged, preference color harmony scheme Is the complementary color scheme that is easy for identification, rather than analogous color scheme. The preferred dominant color is warm color rather than cool color.

• ETRI Journal
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• v.37 no.4
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• pp.717-726
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• 2015

In this paper, we study an asymmetric two-way relaying network where two source nodes intend to exchange information with the help of multiple relay nodes. A hybrid time-division broadcast relaying scheme with joint relay selection (RS) and power allocation (PA) is proposed to realize energy-efficient transmission. Our scheme is based on the asymmetric level of the two source nodes' target signal-to-noise ratio indexes to minimize the total power consumed by the relay nodes. An optimization model with joint RS and PA is studied here to guarantee hybrid relaying transmissions. Next, with the aid of our proposed intelligent optimization algorithm, which combines a genetic algorithm and a simulated annealing algorithm, the formulated optimization model can be effectively solved. Theoretical analyses and numerical results verify that our proposed hybrid relaying scheme can substantially reduce the total power consumption of relays under a traffic asymmetric scenario; meanwhile, the proposed intelligent optimization algorithm can eventually converge to a better solution.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.484-498
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• 2004

In this paper. we propose a novel performance monitoring scheme for heterogeneous SOAP nodes. The scheme is basically based on two-level (kernel-level and user-level) packet filtering of TCP flows. By TCP flow, we mean a sequence of raw packet streams on a TCP transaction. In this scheme, we detect and extract SOAP operations embedded in SOAP messages from TCP flows. Therefore, it becomes possible to monitor heterogeneous SOAP nodes deployed on diverse SOAP-based middlewares such as .Net and Apache AXIS. We present two implementation mechanisms for the proposed scheme. The first mechanism tries to identify SOAP operations by analyzing all fragmented SOAP messages on TCP flows. However, a naive policy would incur untolerable overhead since it needs to copy all packets from kernel to user space. The second mechanism overcomes this problem by selectively copying packets from kernel to user space. For selective copying, we use a kernel-level packet filtering method that makes use of some representative TCP flags.(e.g. SIN, FIN and PSH). In this mechanism, we can detect SOAP operations only from the last fragment of SOAP messages in most cases. Finally, we implement a SOAP monitoring system using a component ca]led SOAP Sniffer that realizes our proposed scheme, and show experimental results. We strongly believe that our system will play a vital role as a tool for various services such as transaction monitoring and load balancing among heterogeneous SOAP nodes.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.32-42
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• 2011

Frequency reuse among relay stations (RSs) in a down-link access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since the areas covered by the RSs or the base station (BS) may overlap, some mobile stations (MSs) at the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the cell degrades the quality of service (QoS) fairness among the MSs as well as the system throughput. Exclusive use of a frequency band division (orthogonal resource allocation) among RSs can solve this problem but would cause degradation of the system throughput. We observe a trade-off between system throughput and QoS fairness in the previously reported schemes based on frequency reuse. In this paper, we propose a new frequency reuse scheme that achieves high system throughput with a high fairness level in QoS, positioning our scheme far above the trade-off curve formed by previous schemes. We claim that our scheme is beneficial for applications in which a high QoS level is required even for the MSs at the border. Exploiting the features of a directional antenna in the BS, we create a new zone in the frame structure. In the new zone, the RSs can serve the subordinate MSs at the border and prone to interference. In a 3-RS topology, where the RSs are located at points $120^{\circ}$ apart from one another, the throughput and Jain fairness index are 10.64 Mbps and 0.62, respectively. On the other hand, the throughput for the previously reported overlapped and orthogonal allocation schemes is 8.22 Mbps (fairness: 0.48) and 3.99 Mbps (fairness: 0.80), respectively. For a 6-RS topology, our scheme achieves a throughput of 18.38 Mbps with a fairness of 0.68; however, previous schemes with frequency reuse factors of 1, 2, 3, and 6 achieve a throughput of 15.24 Mbps (fairness: 0.53), 12.42 Mbps (fairness: 0.71),8.84 Mbps (fairness: 0.88), and 4.57 Mbps (fairness: 0.88), respectively.

• Journal of Power Electronics
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• v.13 no.6
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• pp.939-954
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• 2013

The Direct Torque Control (DTC) technique for Permanent Magnet Synchronous Motors (PMSM) is receiving increased attention due to its simplicity and robust dynamic response when compared with other control techniques. The classical switching table based DTC results in large flux and torque ripples in the motors. Several studies have been reported in the literature on classical DTC. However, there are only limited studies that actually discuss or evaluate the classical DTC. This paper proposes, novel switching table / DTC methods for PMSMs to reduce torque ripples. In this paper, two DTC schemes are proposed. The six sector and twelve sector methodology is considered in DTC scheme I and DTC scheme II, respectively. In both DTC schemes a simple modification is made to the classical DTC structure. The two level inverter available in the classical DTC is eliminated by replacing it with a three level Neutral Point Clamped (NPC) inverter. To further improve the performance of the proposed DTC scheme I, the available 27 voltage vectors are allowed to form different groups of voltage vectors such as Large - Zero (LZ), Medium - Zero (MZ) and Small - Zero (SZ), where as in DTC scheme II, all of the voltage vectors are considered to form a switching table. Based on these groups, a novel switching table is proposed. The proposed DTC schemes are comparatively investigated with the classical DTC and existing literatures through theory analysis and computer simulations. The superiority of the proposed DTC method is also confirmed by experimental results. It can be observed that the proposed techniques can significantly reduces the torque ripples and improves the quality of current waveform when compared with traditional and existing methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.445-453
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• 2002

We propose a cell-multiplexing scheme for the real-time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy. The proposed scheme consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real-time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic

• The Mathematical Education
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• v.43 no.2
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• pp.115-137
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• 2004

In this paper, we verified the effect and appropriateness of the scheme to cure the math. disliking disposition which is the cause of underachievement in learning. We choose 3 middle schools as the subject of experiment for this research. Each experiment class consists of 27∼30 students(underachievers) whose final test results of 1st school year in the middle school are 30∼60 points. In this case, we also select some middle level students whose test results are more than 60 points for the normal experimental condition. For this research, we developed the suitable test materials to cure the mathematics disliking disposition of underachievers. We applied those test materials to the experiment schools during 2.5 months and we analysed the variation of disliking disposition, the variation of math. dislike students' number and the cure rate of the math. disliking disposition. From the results of this experimental study, we find that the factors of teacher and math recognition environment have only the significant difference of math. disliking disposition between experiment class and comparison class under the 5% significance level in one middle school. We understand that this results caused by teachers' careful advice and guidance in that middle school. We also find that the number of student who dislike mathematics decreased in two middle schools. Furthermore 50% of math. disliking dispositions are cured for 9 disliking factors in the lower grade group(the group of underachievers) and as a whole, we can see that 50% of cure rate for the 7 factors of math. disliking in two middle schools. So we can understand that the experiment of our research was performed successfully in two middle schools. In this research, we find out that the scheme to cure the disliking dispositions for the factors of math. disliking depends on the factors of teacher who take charge of cure. So teachers must take interest in and must have careful concern to students and their math. disliking.