• 전자공학회논문지 IE
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• v.44 no.1
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• pp.20-26
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• 2007

Most researches on the mobile ad hoc network (MANET) have been focused on routing protocols, but for the real service provision DNS(Domain Name System) has to be supported first. Due to the inherent characteristics of the mobile ad hoc network, the DNS of the wired network is assumed to be not good for the MANET environment. The approach of distributed DNSs can easily adapt to the node mobility, but incurs the name conflict resolution overhead. On the other hand, the centralized approach performs the name resolution based on the unicast communication without causing the name conflict resolution overhead. The most important issue of the centralized approach is to provide the seamless name resolution service under server mobility. Therefore, in this paper, we propose a new centralized DNS, Manet DNS, which works efficiently on name allocation and management and solves the network merging and partitioning problem as well as providing the seamless name resolution service.

• Journal of Digital Contents Society
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• v.19 no.1
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• pp.103-112
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• 2018

In this paper, we propose a method of recognizing emotions using PPG sensor which measures blood flow according to emotion. From the existing PPG signal, we use a method of determining positive emotions and negative emotions in the frequency domain through PSD (Power Spectrum Density). Based on James R. Russell's two-dimensional prototype model, we classify emotions as joy, sadness, irritability, and calmness and examine their association with the magnitude of energy in the frequency domain. It is significant that this study used the same PPG sensor used in wearable devices to measure the top four kinds of emotions in the frequency domain through image experiments. Through the questionnaire, the accuracy, the immersion level according to the individual, the emotional change, and the biofeedback for the image were collected. The proposed method is expected to be various development such as commercial application service using PPG and mobile application prediction service by merging with context information of existing smart phone.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.237-246
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• 2001

A high speed context-free marker-controlled and minima imposition-free watershed transform is proposed for efficient multi-object detection and segmentation from a complex background. The context-free markers are extracted from a complex backgrounded multi-object image using a noise tolerant attention operator. These make marker-controlled watershed possible for the over-segmentation reduction without region merging. The proposed method presents a marker-constrained labeling that can speed up the segmentation of a marker-controlled watershed transform by eliminating the necessity of the minima imposition. Simulation results show that the proposed method can efficiently detects and segments multiple objects from a complex background while reducing over- segmentation and the computation time.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.104-115
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• 1999

This paper proposes an efficient method for 3D modeling of a human face from trinocular images by reconstructing face surface using range data. By using a trinocular camera system, we mitigated the tradeoff between the occlusion problem and the range resolution limitation which is the critical limitation in binocular camera system. We also propose an MPC_MBS (Matching Pixel Count Multiple Baseline Stereo) area-based matching method to reduce boundary overreach phenomenon and to improve both of accuracy and precision in matching. In this method, the computing time can be reduced significantly by removing the redundancies. In the model generation sub-pixel accurate surface data are achieved by 2D interpolation of disparity values, and are sampled to make regular triangular meshes. The data size of the triangular mesh model can be controlled by merging the vertices that lie on the same plane within user defined error threshold.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.1
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• pp.38-46
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• 2004

Image segmentation is the task which partitions the image into meaningful regions and considered to be one of the most important steps in computer vision and image processing. Image segmentation is also widely used in object-based video compression such as MPEG-4 to extract out the object regions from the given frame. Watershed algorithm is frequently used to obtain the more accurate region boundaries. But, it is well known that the watershed algorithm is extremely sensitive to gradient noise and usually results in oversegmentation. To solve such a problem, we propose an image segmentation method which is robust to noise by using stabilized inverse diffusion equation (SIDE) and is more efficient in segmentation by employing multiresolution approach. In this paper, we apply both the region projection method using labels of adjacent regions and the region merging method based on region adjacency graph (RAG). Experimental results on noisy image show that the oversegmenation is reduced and segmentation efficiency is increased.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.49-54
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• 2007

As digital contents based on 3D graphics are increased, the requirement for low power 3D graphic hardware for mobile devices is increased. We design a transformation engine for mobile 3D graphic processor. We propose a simplified transformation engine for mobile 3D graphic processor. The area of the transformation engine is reduced by merging a mapping transformation unit into a projective transformation unit and by replacing a clipping unit with a selection unit. It consists of a viewing transformation unit a projective transformation unit a divide by w nit, and a selection unit. It can process 32 bit floating point format of the IEEE-754 standard or a reduced 24 bit floating point format. It has a pipelined architecture so that a vertex is processed every 4 cycles except for the initial latency. The RTL code is verified using an FPGA.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.787-794
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• 2018

The various natural disasters such as floods and localized heavy rains are increasing due to the global warming. If a natural disaster can be detected and analyzed in advance and more effectively, it can prevent enormous damage of natural disasters. Recent development in visual sensor technologies has encouraged various studies on monitoring environments including rivers. In this paper, we propose a method to detect water regions from river images which can be exploited for river surveillance systems using video sensor networks. In the proposed method, we first segment a river image finely using the minimum spanning tree algorithm. Then, the seed regions for the river region and the background region are set by using the preliminary information, and each seed region is expanded by merging similar regions to segment the water region from the image. Experimental results show that the proposed method separates the water region from a river image easier and accurately.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.406-417
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• 2001

With the advances in multimedia databases on the World Wide Web, it becomes more important to provide users with the search capability of distributed multimedia data. While there have been many studies about the database selection and the collection fusion for text databases. The multimedia databases on the Web have autonomous and heterogeneous properties and they use mainly the content based retrieval. The collection fusion problem of multimedia databases is concerned with the merging of results retrieved by content based retrieval from heterogeneous multimedia databases on the Web. This problem is crucial for the search in distributed multimedia databases, however, it has not been studied yet. This paper provides novel algorithms for processing the collection fusion of heterogeneous multimedia databases on the Web. We propose two heuristic algorithms for estimating the number of objects to be retrieved from local databases and an algorithm using the linear regression. Extensive experiments show the effectiveness and efficiency of these algorithms. These algorithms can provide the basis for the distributed content based retrieval algorithms for multimedia databases on the Web.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.409-421
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• 2004

A database sharing system (DSS) couples a number of computing nodes for high performance transaction processing, and each node in DSS shares database at the disk level. In case of node failures in DSS, database recovery algorithms are required to recover the database in a consistent state. A database recovery process in DSS takes rather longer time compared with single database systems, since it should include merging of discrete log records in several nodes and perform REDO tasks using the merged lo9 records. In this paper, we propose a two version caching (2VC) algorithm that improves the cache fusion algorithm introduced in Oracle 9i Real Application Cluster (ORAC). The 2VC algorithm can achieve faster database recovery by eliminating the use of merged log records in case of single node failure. Furthermore, it can improve the performance of normal transaction processing by reducing the amount of unnecessary disk force overhead that occurs in ORAC.

• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.775-782
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• 2005

In this paper, we propose multicast technique in order to reduce the required network bandwidth by n times, by merging the adjacent multicasts depending on the number of HENs (Head-End-Nodes) n that request the same video. Allowing new clients to immediately join an existing multicast through patching improves the efficiency of the multicast and offers services without any initial latency. A client might have to download data through two channels simultaneously, one for multicast and the other for patching. The more the frequency of requesting the video is, the higher the probability of caching it among HENs increases. Therefore, the requests for the cached video data can be served by HENs. Multicast from server is generated when the playback time exceeds the amount of cached video data. Since the interval of multicast can be dynamically expanded according to the popularity of videos, it can be reduced the server's workload and the network bandwidth. We perform simulations to compare its performance with that of conventional multicast. From simulation results, we confirm that the Proposed multicast technique offers substantially better performance.