• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.595-598
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• 2005

MPEG-4 Visual is, and international standard for the object-based video compression, designed for supporting a wide range of applications from multimedia communication to HDTV. To control the minimum decoding complexity required at the decoder, the MPEG-4 Visual standard defines the co-called video buffering mechanism, which includes three video buffer models. Among them, the VCV(Video Complexity Verifier) defines the control of the processing speed for decoding of a macroblock, there are two models: VCV and B-VCV distinguishing the boundary and non-boundary MB. This paper presents the evaluation results of decoding complexity by measuring decoding time of a MB for rectangular, arbitrarily shaped video objects and the various types of objects supporting the resolution of HDTV using the optimized MPEG-4 Reference Software. The experimental results shows that decoding complexity varies depending on the coding type and more effective usage of decoding resources may be possible.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3138-3147
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• 2000

EC(Electronic Commerce) which is cone the virtual space through Internet, has the advantage of time and space. On the contrary, it also has weak point like security probelm because anybody can easily access to the system due to open network attribute of Internet. Theretore, we need the solutions that protect the EC security problem for safe and useful EC activity. One of these solution is the implemonlation of a strong cipher algorithm. YK2(YoungKu Kang) cipher algorithm proposed in this paper is advantage for the EC security and it overcomes the limit of the current 6/1 bits block cipher algorithm using 128 bits key length for input, output, encryption key and 32 rounds. Moreover, it is degigned for the increase of time complexity and probability calculation by adapting more complex design for key scheduling regarded as one of the important element effected to enciyption.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.843-850
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• 2006

This is devoted to first, to propose a hash chain algorithm that generates more secure key than conventional encryption method. Secondly, we proposes encryption method that is more secure than conventional system using a encryption method that encrypts each block with each key generated by a hash chain algorithm. Thirdly, After identifying the user via wired and wireless network using a user authentication method. We propose a divided session key method so that Although a client key is disclosed, Attackers cannot catch a complete key and method to safely transfer the key using a divided key method. We make an experiment using various size of digital contents files for performance analysis after performing the design and implementation of system. Proposed system can distribute key securely than conventional system and encrypt data to prevent attacker from decrypting complete data although key may be disclosed. The encryption and decryption time that client system takes to replay video data fie is analogous to the conventional method.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.20-27
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• 2013

In recently years, with the growth of social media and the development of mobile devices, the data have been significantly increased. MapReduce is an emerging programming model that processes large amount of data. However, since MapReduce evenly places the data in the dedicated distributed computing environment, it is not suitable to the non-dedicated distributed computing environment. The data replacement algorithms were proposed for performance optimization of MapReduce in the non-dedicated distributed computing environments. However, they spend much time for date replacement and cause the network load for unnecessary data transmission. In this paper, we propose an efficient data replacement algorithm for the performance optimization of MapReduce in the non-dedicated distributed computing environments. The proposed scheme computes the ratio of data blocks in the nodes based on the node availability model and reduces the network load by transmitting the data blocks considering the data placement. Our experimental results show that the proposed scheme outperforms the existing scheme.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.5
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• pp.189-196
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• 2022

Skyline query is a scheme for exploring objects that are suitable for user preferences based on multiple attributes of objects. Existing skyline queries return search results as batch processing, but the need for real-time search results has increased with the advent of interactive apps or mobile environments. Online algorithm for Skyline improves the return speed of objects to explore preferred objects in real time. However, the object navigation process requires unnecessary navigation time due to repeated comparative operations. This paper proposes a Pre-processing Online Algorithm for Skyline Query (POA) to eliminate unnecessary search time in Online Algorithm exploration techniques and provide the results of skyline queries in real time. Proposed techniques use the concept of range-limiting to existing Online Algorithm to perform pretreatment and then eliminate repetitive rediscovering regions first. POAs showed improvement in standard distributions, bias distributions, positive correlations, and negative correlations of discrete data sets compared to Online Algorithm. The POAs used in this paper improve navigation performance by minimizing comparison targets for Online Algorithm, which will be a new criterion for rapid service to users in the face of increasing use of mobile devices.

• The KIPS Transactions:PartB
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• v.13B no.2 s.105
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• pp.105-114
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• 2006

In ubiquitous environment where various kinds of computers are embedded in persons, objects and environment and they are interconnected and can be used in my place as necessary, different types of data need to be exchanged between heterogeneous machines through home network. In the environment, the efficient processing, transmission and monitoring of image data are essential technologies. We need to make research not only on traditional image processing such as spatial and visual resolution, color expression and methods of measuring image quality but also on transmission rate on home network that has a limited bandwidth. The present study proposes a new motion vector estimation algorithm for transmitting, processing and controlling image data, which is the core part of contents in home network situation and, using algorithm, implements a real time monitoring system of multi dimensional images transmitted from multiple cameras. Image data of stereo cameras to be transmitted in different environment in angle, distance, etc. are preprocessed through reduction, magnification, shift or correction, and compressed and sent using the proposed metamorphosis hierarchical motion vector estimation algorithm for the correction of motion. The proposed algorithm adopts advantages and complements disadvantages of existing motion vector estimation algorithms such as whole range search, three stage search and hierarchical search, and estimates efficiently the motion of images with high variation of brightness using an atypical small size macro block. The proposed metamorphosis hierarchical motion vector estimation algorithm and implemented image systems can be utilized in various ways in ubiquitous environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.1
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• pp.129-141
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• 2024

Amidst the acceleration of digital transformation across various sectors, the financial market is increasingly focusing on the development of digital and electronic payment methods, including currency. Among these, Central Bank Digital Currencies (CBDC) are emerging as future digital currencies that could replace physical cash. They are stable, not subject to value fluctuation, and can be exchanged one-to-one with existing physical currencies. Recently, both domestic and international efforts are underway in researching and developing CBDCs. However, current CBDC systems face scalability issues such as delays in processing large transactions, response times, and network congestion. To build a universal CBDC system, it is crucial to resolve these scalability issues, including the low throughput and network overload problems inherent in existing blockchain technologies. Therefore, this study proposes a solution based on reinforcement learning for handling large-scale data in a CBDC environment, aiming to improve throughput and reduce network congestion. The proposed technology can increase throughput by more than 64 times and reduce network congestion by over 20% compared to existing systems.

• Journal of Conservation Science
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• v.30 no.2
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• pp.137-148
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• 2014

Large scale anoxic chamber system(volume $28m^3$) was developed and installed at The National Folk Museum of Korea for the first time in Korea. In order to get optimal anoxic treatment condition, we compared the disinfection of adults, larvae and eggs of cigarette beetles using nitrogen and argon. The time for complete disinfection of cigarette beetles in pine wooden blocks exposed to nitrogen at oxygen concentration 0.01% and 50% in relative humidity were 15 days at $20^{\circ}C$, 10 days at $25^{\circ}C$, and 7 days $30^{\circ}C$. Time were 10 days at $20^{\circ}C$, 7 days at $25^{\circ}C$, and 5 days $30^{\circ}C$ in argon anoxic atmosphere. From the mortality of cigarette beetles, optimal disinfection condition was oxygen concentration 0.01%, $25^{\circ}C$ in temperature, 50% in relative humidity and exposure time 21 days at nitrogen atmosphere. And when large scale anoxic chamber system was supplied nitrogen by nitrogen generator for anoxic treatment of many collections or large collections, it could be operated stably. To verify optimal disinfection condition, museum insects(adults, larvae, pupae and eggs of cigarette beetles in pine wooden blocks, cotton fabrics and Korean paper book, adults and larvae of drugstore beetles in pine wooden blocks, cotton fabrics and Korean paper book, larvae of varied carpet beetles in pine wooden block and silk fabrics, adults and larvae of hide beetles and adults of rice weevils in breeding boxes) which exposed at optimal disinfection condition, were completely killed.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.675-688
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• 2007

Memory access errors are frequently occurred in C programs. A number of tools and research works have been trying to detect the errors automatically. However, they have one or more of the following problems: inability to detect all memory errors, changing the memory allocation mechanism, incompatibility with libraries, and excessive performance overhead. In this paper, we suggest a new method to solve these problems, and then present a result of comparison to the previous research works through the experiments. Our approach consists of two phases. First is to transform source code at compile time through inserting instrumentation into the source code. And second is to detect memory errors at run time with a bitmap that maintains information about memory allocation. Our approach has improved the error detection abilities against the binary code analysis based ones by using the source code analysis technique, and enhanced performance in terms of both space and time, too. In addition, our approach has no problem with respect to compatibility with shared libraries as well as does not need to modify memory allocation mechanism.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.27-32
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• 2013

Purpose: The aims of this study were to evaluate the effect of a resin coating on the shear bond strength of indirect composite restoration bonded to dentin with a self adhesive resin cement and to compare the shear bond strength with that of a conventional resin cement. Materials and methods: The occlusal enamels of thirty six extracted noncarious human molars were removed until the dentin flat surfaces of the teeth were exposed. Then, they were divided into 3 groups. The dentin surfaces of group 1 and 3 were left without any conditioning, while the dentin surfaces of group 2 were resin-coated with Clearfil SE bond and a flowable resin composite, Metafil Flo. After all specimens were temporized for 24 hours, indirect composite resin blocks fabricated by Tescera were bonded to dentins by Unicem for group 1 and 2, and by Panavia F for group 3. After 48 hours of water storage, shear bond strengths were measured. The data was analyzed with one-way analysis of variance and multiple comparison test (Tukey method). Results: The shear bond strengths of Unicem applied to resin coated dentin surfaces were significantly higher than those of Unicem and Panavia F used to uncoated dentin surfaces (P<.0001). Conclusion: Application of a resin coating to the dentin surface significantly improved the shear bonding strength of a self adhesive resin cement in indirect restoration.