• The Journal of the Acoustical Society of Korea
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• v.24 no.4
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• pp.202-209
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• 2005

The rapid development of digital media and communication network urgently brings about the need of data certification technology to protect IPR (Intellectual property right). This paper proposed a new watermarking method for embedding owner's audio signal. Because this method uses an audio signal as a watermark to be embedded, it is very useful to claim the ownership aurally. And it has the advantage of restoring audio signal modified and especially removed by image removing attacks by applying our LBX(Linear Bit-expansion) interleaving. Three basic stages of our watermarking include: 1) Encode . analogue owner's audio signal by PCM and create new digital audio watermark, 2) Interleave an audio watermark by our LBX; and 3) Embed the interleaved audio watermark in the low frequency band on DTn (Discrete Haar Wavelet Transform) of image. The experimental results prove that this method is resistant to lossy JPEG compression as standard image compression and especially to cropping and rotation which remove a part of Image.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.49-56
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• 2011

Recently, animation contents has become extensively available along with the development of cultural industry. In this paper, we propose a method to analyze a face of animation character and extract 3D rotational information of the face. The suggested method first generates a dominant color model of a face by learning the face image of animation character. Our system then detects the face and its components with the model, and establishes two coordinate systems: base coordinate system and target coordinate system. Our system estimates three dimensional rotational information of the animation character face using the geometric relationship of the two coordinate systems. Finally, in order to visually represent the extracted 3D information, a 3D face model in which the rotation information is reflected is displayed. In experiments, we show that our method can extract 3D rotation information of a character face reasonably.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.750-753
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• 2005

Internet service, a part of our life, requires the changes not only of environment in our life but also of people's sense of value. It also requires a quick change in the spear of education activities without exception. It brought a lot of changes into educational methods, our recognition on education, and various kinds of educational tools and environment. The introduction of WBI (Web Based Instruction) is one of the most important thing. This study have applied WBI to Industrial high school education to improve its quality and accomplish its effective teaching-learning. That is, we have applied CNC(Computerized Numerical Control) and Processing learning to machining center learning and have given students chances and various learning materials so that they could contact with new information. We aimed at testing and studying some effects on the improvements of learning accomplishment and motive in this study.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.61-68
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• 2015

Recently, with increasing use of smartphones, the security threats also have increased rapidly. Especially, the compromised smartphone is very dangerous because it could be exploited in a DDOS attacks such as cyberterrorism as well as in the leakage of personal information. However, most bot detection mechanisms are still unsuitable for smartphone with its lower computing capability and limited battery capacity because they incur additional computational overheads or require pre-defined signatures. In this paper, we present an efficient bot detection mechanism in smartphones. Our mechanism detects effectively bots in outgoing traffic by using a correlation between user events and network traffic. We have implemented its prototype in Android smartphone and measured its performance. The evaluation results show that our mechanism provides low overhead to detect bots in smartphones.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.467-476
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• 2009

As web technology and educational environments are in rapid progress, web-based cooperative learning systems have gained a lot of interests. Recently some studies have attempted to combine a learning system and simple games that enable learners to actively participate and have high interests in learning. These studies are based on TGT model, a cooperative learning model using games, and mostly remain system design levels. A few implemented systems have many problems because they focus only on pure TGT model. To solve these problems, this paper builds a extended TGT model and a new web-based cooperative learning system using this new model. The extended part contains ideas such as expert learning from Jigsaw II model, improvement scores from STAD model and making game problems by learners. A system using pure TGT model and a suggested system are implemented and used by two classes of middle school students to evaluate our system. The experimental results show that our system outperforms the other system.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.1030-1036
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• 2006

The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. This paper presents an efficient rough set based anomaly detection method that can effectively identify a group of especially harmful internal masqueraders in cellular mobile networks. Our scheme uses the trace data of wireless application layer by a user as feature value. Based on the feature values, the use pattern of a mobile's user can be captured by rough sets, and the abnormal behavior of the mobile can be also detected effectively by applying a roughness membership function considering weighted feature values. The performance of our scheme is evaluated by a simulation. Simulation results demonstrate that the anomalies are well detected by the method that assigns different weighted values to feature attributes depending on importance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2073-2081
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• 2013

Today's rapidly changing society can lead to maladaptive behaviors. In the situations, rehabilitation psychology analysis using the on-line test be needed to solve the problem. However, Internet-based rehabilitation psychology analysis by a malicious attacker may still be vulnerable to denial-of-service attacks. The service flooding attacks render the server incapable of providing its service to legitimate clients. Therefore the importance of implementing systems that prevent denial of service attacks and provide service to legitimate users cannot be overemphasized. In this paper, we propose a puzzle protocol which applies to authentication model. our gradually strengthening authentication model improves the availability and continuity of services and prevent denial of service attacks and we implement flooding of service tolerance system to verify the efficiency of our model. This system is expected to be ensure in the promotion of reliability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.8
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• pp.672-678
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• 2013

In the recent year, along with the rapid development of LED technology, many applications using LEDs have been researched and indoor positioning is one of them. In particular, previous indoor positioning systems based on visible light communication combine triangulation manner such as AoA, ToA TDoA. But most of them needs transmitting unique ID of each LED panel. In this paper, we propose an non LED-ID based indoor positioning system in which the visible light radiated from LEDs is used to locate the position of receiver. Compared to current indoor positioning systems using LED light, our system has the advantages of simple implementation, low cost and high accuracy. Through the computer simulation, our system can achieve a high estimation accuracy of 3.6cm in average in the $5{\times}5{\times}3m^3$ room.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.332-337
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• 2006

We prepared 100 nm-thick CoNi composite silicide on a 70 nm-thick polysilicon substrate. Composite silicide laye.s were formed by rapid thermal annealing(RTA) at the temperatures of $700^{\circ}C,\;900^{\circ}C,\;1000^{\circ}C$ for 40 seconds. A Focused ion beam (FIB) was used to make nano-patterns with the operation range of 30 kV and $1{\sim}100$ pA. We investigated the change of thickness, line width, and the slope angle of the silicide patterns by FIB. More easily made with the FIB process than with the conventional polycide process. We successfully fabricated sub-100nm etched patterns with FIB condition of 30kv-30pA. Our result implies that we may integrate nano patterns with our newly proposed CoNi composite silicides.

• Journal of Internet Computing and Services
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• v.5 no.4
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• pp.77-94
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• 2004

Recently, the needs of index structure which manages moving objects efficiently have been increased because of the rapid development of location-based techniques. Existing index structures frequently need updates because moving objects change continuatively their positions. That caused entire performance loss of the index structures. In this paper, we propose a new index structure called the TPKDB-tree that is a spatio-temporal index structure based on KDB-tree. Our technique optimizes update costs and reduces a search time for moving objects and reduces unnecessary updates by expressing moving objects as linear functions. Thus, the TPKDB-tree efficiently supports the searches of future positions of moving objects by considering the changes of moving objects included in the node as time-parameter. To maximize space utilization, we propose the new update and split methods. Finally, we perform various experiments to show that our approach outperforms others.