• Journal of KIISE:Computer Systems and Theory
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• v.34 no.11
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• pp.581-588
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• 2007

In Digital Right Management, symmetric cipher is used for content encryption to reduce encryption cost, AES, advanced encryption standard is usually used to multimedia encryption under desktop environment because of its reasonable security level and computation cost. But mobile handheld device often uses slow speed processor and operates under battery-powered environment. Therefore it requires low computation cost and low energy consumption. This paper proposes new stream cipher scheme which combines pseudo random number generator(PRNG) and dynamically generated permutations. Proposed scheme activates PRNG and generates original key streams. Then it generates extended key streams by applying permutation to original sequence. These extended key streams are XORed with plaintext and generate ciphertext. Proposed scheme reduces the usage of PRNG. Therefore this scheme is fast and consumes less energy in comparison with normal stream cipher. Especially, this scheme shows great speed up (almost 2 times) than normal stream cipher scheme in random access.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1094-1101
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• 2013

This paper proposes an improved branch predictor that reduces the number execution cycles of applications by selectively accessing a specific element in 4-way associative cache. When a branch instruction is fetched, the proposed branch predictor acquires a branch target address from the selected element in the cache by referring to MRU buffer. Branch prediction rate and application execution speed are considerably improved by increasing the number of BTAC entries in restricted power condition, when compared with that of previous branch predictor which accesses all elements. The effectiveness of the proposed dynamic branch predictor is verified by executing benchmark applications on the core simulator. Experimental results show that number of execution cycles decreases by an average of 10.1%, while power consumption increases an average of 7.4%, when compared to that of a core without a dynamic branch predictor. Execution cycles are reduced by 4.1% in comparison with a core which employs previous dynamic branch predictor.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.130-136
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• 2009

Turbine, which is one of major components in nuclear power plants, requires reliable nondestructive inspections. But, accessibility of transducers is limited and interpretation of acquired signals is not easy at all due to the complication. So, in this study, we have fabricated mock-up specimens of real size and shape. we applied pulse-echo method and time-of-flight diffraction(TOFD) method for precise inspection of turbine key and wheel bore. And phased array ultrasonic testing method was adopted for wheel dovetail of turbines by using mock-up. Furthermore, an automatic scanner system was developed for in-service inspection of the developed methods.

• Journal of KIISE:Software and Applications
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• v.32 no.8
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• pp.819-833
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• 2005

Code size reduction is ever becoming more important for compilers targeting embedded processors because these processors are often severely limited by storage constraints and thus the reduced code size can have a positively significant Impact on their performance. Various code size reduction techniques have different motivations and a variety of application contexts utilizing special hardware features of their target processors. In this work, we propose a novel technique that fully utilizes a set of hardware instructions, called the multiple load/store (MLS), that are specially featured for reducing code size by minimizing the number of memory operations in the code. To take advantage of this feature, many microprocessors support the MLS instructions, whereas no existing compilers fully exploit the potential benefit of these instructions but only use them for some limited cases. This is mainly because optimizing memory accesses with MLS instructions for general cases is an NP-hard problem that necessitates complex assignments of registers and memory off-sets for variables in a stack frame. Our technique uses a couple of heuristics to efficiently handle this problem in a polynomial time bound.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.88-93
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• 2015

In modern computer systems, DRAM is commonly used as main memory due to its low read/write latency and high endurance. However, DRAM is volatile memory that requires periodic power supply (i.e., memory refresh) to sustain the data stored in it. On the other hand, PCM is a promising candidate for replacement of DRAM because it is non-volatile memory, which could sustain the stored data without memory refresh. PCM is also available for byte-addressable access and in-place update. However, PCM is unsuitable for using main memory of a computer system because it has two limitations: high read/write latency and low endurance. To take the advantage of both DRAM and PCM, a hybrid main memory, which consists of DRAM and PCM, has been suggested and actively studied. In this paper, we propose a novel page replacement algorithm for hybrid main memory. To cope with the weaknesses of PCM, our scheme focuses on reducing the number of PCM writes in the hybrid main memory. Experimental results shows that our proposed page replacement algorithm reduces the number of PCM writes by up to 80.5% compared with the other page replacement algorithms.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.206-211
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• 2017

Recently computing devices by connecting to a network, grid computing, the next generation of digital neural networks that provide maximum service will connect all of the computer such as a PC or server, PDA into one giant network makes the virtual machine. Therefore, we propose the grid computing implementation model to be applied to meteorological business field as follows. First, grid computing will be used for tasks such as the development of numerical models below the mid-scale or test operations, and the final backup of the weather supercomputer. Second, the resources that will constitute grid computing are limited to business PCs and Linux servers operated by the central government considering operational efficiency. Third, the network is restricted to the LAN section, which suggests the implementation of high performance computing.

• Journal of KIISE
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• v.44 no.12
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• pp.1245-1251
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• 2017

In this study we present a novel directory architecture that can dynamically allocate a directory entry for a cache block on demand at runtime only when the block is shared by more than one core. Thus, we do not maintain coherence for private blocks, substantially reducing the number of directory entries. Even for shared blocks, we allocate directory entry dynamically only when the block is actively shared, further reducing the number of directory entries at runtime. For this, we propose a new directory architecture called dynamic directory table (DDT), which is implemented as a cache of active directory entries. Through our detailed simulation on PARSEC benchmarks, we show that DDT can outperform the expensive full-map directory by a slight margin with only 17.84% of directory area across a variety of different workloads. This is achieved by its faster access and high hit rates in the small directory. In addition, we demonstrate that even smaller DDTs can give comparable or higher performance compared to recent directory optimization schemes such as SPACE and DGD with considerably less area.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1530-1535
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• 2008

수자원과 관련된 많은 분쟁 및 갈등들은 국내뿐만 아니라 전 세계적으로 발생하고 있다. 따라서 분쟁 및 갈등해결을 위한 많은 연구들이 진행되고 있지만 수자원과 관련된 분쟁들은 대부분 원활한 해결을 이루지 못하고 있으며, 특히 국내의 경우에는 더욱 심각하다 할 수 있다. 따라서 제한된 자원인 수자원을 둘러싸고 수자원분쟁이 일어나는 것은 당연한 일이라 할 수 있으며, 분쟁의 양상도 다양하다. 댐 건설로 인한 상류지역과 하류지역의 갈등, 수로의 건설로 인해 수자원을 빼앗기는 지역과 수자원을 얻게 되는 지역 간의 갈등, 새로운 공단이나 개발로 인하여 하류지역에서 수질악화를 우려하여 반대하는 경우 등 여러 종류의 수자원으로 인한 분쟁이 있다. 수자원을 둘러싼 갈등이 쉽게 해결이 되지 않고, 또한 갈등 및 분쟁이 쉽게 발생되는 이유도 주체자들간 입장 차이에서 오는 성격이라 할 수 있겠다. 수자원과 관련된 분쟁에서 오는 여러 가지 갈등들은 사회적으로 많은 문제들을 발생시켜 수자원의 원활한 공급이 저해될 수 있다. 이로 인해 사회적으로 수자원과 관련된 분쟁 해결에 들어가는 많은 시간과 노력, 비용을 생각해 볼 때, 효과적인 갈등 및 분쟁의 해결은 국가적 발전에 있어서 영향을 줄 수 있다. 그러므로 갈등 및 분쟁의 원활한 해결이 국가적 발전에 많은 비중을 차지 한다고 할 수 있다는 것은 이런 이유들 때문이라 할 수 있다. 본 연구에서는 국내 수자원과 관련된 분쟁사례들을 하천의 기능에 따른 분류, 발생 원인에 따른 분류, 분쟁주체에 따른 분류 등을 유형별로 구분하여 수자원분쟁의 여러 가지 사례들을 조사하였다. 또한 분쟁 및 갈등을 해결하기 위한 방안으로 거버넌스 시스템을 적용하였고 분쟁의 원활한 합의 조정방안 및 문제점을 제시하기 위한 외국의 시민참여 모델을 특징 및 특성을 분석하였다. 또한, 공영시각모형, 게임이론, 제도설계이론의 공학적 모형을 바탕으로 물분쟁의 해결을 위한 대안을 모색할 수 있는 과학적 접근 방안을 제시하여 향후 여러 가지형태의 국책사업 시행 시 발생 할 수 있는 분쟁의 해결 및 조정을 위한 방안으로 활용할 수 있는 토대를 마련하고자 한다.

• Journal of Advanced Navigation Technology
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• v.21 no.3
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• pp.306-311
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• 2017

In the future ubiquitous network, information will collect data from various sensors in the field. Since the sensor nodes are equipped with small, often irreplaceable, batteries with limited power capacity, it is essential that the network be energy-efficient in order to maximize its lifetime. In this paper, we propose an effective network routing method that can operate with low power as well as the transmission of data and information obtained from sensor networks, and identified the number of sensors with the best connectivity to help with the proper placement of the sensor. These purposes of this research are the development of the sensor middle-ware to integrate the maritime information and the proposal of the routing algorithm for gathering the maritime information of various sensors. In addition, for more secure ship navigation, we proposed a method to construct a sensor network using various electronic equipments that are difficult to access in a ship, and then construct a communication system using NMEA(the national marine electronics association), a ship communication standard, in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.200-212
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• 2004

Electronic Navigational Chart is a sophisticated digital chart which contains navigational information such as coastline, depth of water, and nautical mark. It contains high levels of textual, spatial and graphical data, and rapidly replaces traditional paper charts. Although Electronic Navigational Chart has been successfully applied to the navigation of ships, the specific data format, S-57, requires some specialized systems. Furthermore its usage may be limited to specific domains and experts with restrictions. To overcome these limitations resulting from the specific data format, S-57, of Electronic Navigational Chart, more general data format such as XML will be preferred. If Electronic Navigational Chart is transformed into the form of XML, it can be easily accessed and exchanged on the internet. Therefore it may be used for more users and applications. In this paper, we propose an XML. Schema to equivalently represent XML for the S-57 format of Electronic Navigational Chart and develop a program translating the S-57 Electronic Navigational chart to XML document according to the proposed XML schema.