• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.59-66
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• 2019

As the monetary value of cryptocurrency increases, the security measures for cryptocurrency becomes more important. A limitation of the existing cryptocurrency exchanges is their vulnerability to threats of hacking due to their centralized manner of management. In order to overcome such limitation, blockchain technology is increasingly adopted. The blockchain technology enables decentralization and Peer-to-Peer(P2P) transactions, in which blocks of information are linked in chain topology, and each node participating in the blockchain shares a distributed ledger. In this paper, we propose and implement a mobile electronic wallet that can safely store, send and receive cryptocurrencies. The proposed mobile cryptocurrency wallet connects to the network only when the wallet actively is used. Wallet owner manages his or her private key offline, which is advantageous in terms of security. JavaScript based wallet apps were implemented to respectively run on Android and iOS mobile phones. I demonstrate the process of transferring Ethereum cryptocurrency from an account to another account through Ropsten, a test net for Ethereum. Hardware wallets, such as Ledger Nano S, provide a slightly higher level of security, yet have the disadvantages of added burden of carrying additional physical devices and high costs (about 80$).

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.10
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• pp.520-529
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• 2001

Carry-save-adder(CSA) is one of the most effective operation cells in implementing an arithmetic hardware with high performace and small circuit area. An fundamental drawback of the existing CAS applications is that the applications are limited to the local parts of arithmetic circuit that are directly converted to additions. To resolve the limitation, we propose a set of new CSA transformation techniques: optimizing arithmetics with multiplexors, optimizing arithmetics in multiple designs, and optimizing arithmetics with multiplications. We then design a new CSA transformation algorithm which integrates the proposed techniques, so that we are able to utilize CSAs more globally. An extensive experimentation for practical designs are provided to show the effectiveness of our proposed algorithm over the conventional CSA techniques.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.394-396
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• 2006

When developing a new GPS receiver module, the essential problems are evaluation of reliable algorithms, software debugging, and performance comparison between algorithms to find optimal solution. Most GPS receiver modules nowadays use a correlator to track signals from satellites and an MCU (Micro Controller Unit) to control operations of the entire module. The problem of software evaluation from MCU is very difficult, due to limitation of MCU resources and low ability of interfacing with user. Normally, user has to expense special tool kit for a limiting access to MCU but it is also hard to use. This article introduces an implementation of a GPS receiver test bed using correlator GP2021 interfacing with ISA (Industry Standard Architecture) PC bus. This way can give user complete control and visibility into the operation of the receiver, then user can easily debug program and test algorithms. For this article, the least square method is implemented to test the hardware and software performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.659-661
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• 2013

This paper, we study on multiple wireless network module support for the Android based set-top box. Limitation of mobile OS, Android based set-top box has limited choice of various wireless network modules, Atheros, Realtek, Ralink, etc. In this paper, for the request of Set-top box supplier and market demands, we research on reconfigure & change the Android network HAL(Hardware Abstract Layer) for Wi-Fi networking support and implementation about multiple Wi-Fi module support platform.

• Smart Structures and Systems
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• v.5 no.2
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• pp.119-137
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• 2009

Smart sensors densely distributed over structures can use their computational and wireless communication capabilities to provide rich information for structural health monitoring (SHM). Though smart sensor technology has seen substantial advances during recent years, implementation of smart sensors on full-scale structures has been limited. Hardware resources available on smart sensors restrict data acquisition capabilities; intrinsic to these wireless systems are packet loss, data synchronization errors, and relatively slow communication speeds. This paper addresses these issues under the hardware limitation by developing corresponding middleware services. The reliable communication service requires only a few acknowledgement packets to compensate for packet loss. The synchronized sensing service employs a resampling approach leaving the need for strict control of sensing timing. The data aggregation service makes use of application specific knowledge and distributed computing to suppress data transfer requirements. These middleware services are implemented on the Imote2 smart sensor platform, and their efficacy demonstrated experimentally.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.300-302
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• 2017

The Internet of Things allows you to connect everything around you to your network and make it easy to reach anytime, anywhere. The Internet of Things uses various devices such as smart devices and wireless sensors connected to the network. When any small information about command or result is exposed to the outside during communication between each terminal, there is a serious risk. The Internet has a characteristic that it is much weaker than general network in terms of security because it has limited hardware performance. In this paper, I propose an enhanced security architecture of Internet of Things considering the limitation of hardware.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.367-370
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• 2002

In this paper, we propose a new node architecture LonWorh control Network for home network system environmint using power line communications. Using conventional Lon Work technology is a many disputable points for home network. LonWork network system needs high-cost development equipment. Moreover, conventional Lon Work system can not implement high-grade algorithms and variety application operation. because of the limitation of processing ability in Neuron chip. For that reason, the proposed structure is applicable to low-cost and more complex applications which are impossible in home network using conventional Lonworks structure. The proposed structure is implemented with some hardware and かone software for power line home network. The physical layer and the MAC layer of the LonTalk protocol within ton Work are implemented in hardware, which decreases the development costs communication processor. The upper of link layer of the LonTalk protocol is implemented with software, which decreases the development costs of software and increases the flexibility of tile system and increases the extension of the system. We verified the commercial feasibility of the proposed system through the power line tests with the existing LonWorks network in home network. As a result, it is concluded that the proposed architecture provides increasing flexibility and decreasing cost of the system.

• The Journal of the Acoustical Society of Korea
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• v.30 no.3
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• pp.115-122
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• 2011

In this paper, we present a method to estimate an accurate real-time sound source direction based on time delay of arrival by using generalized cross correlation with four cross-type microphones. In general, existing systems have two disadvantages such as system embedding limitation due to the necessity of data acquisition for signal processing from microphone input, and real-time processing difficulty because of the increased number of channels for sound direction estimation using DSP processors. To cope with these disadvantages, the system considered in this paper proposes hardware design for enhanced real-time processing using microphone array signal processing. An accurate direction estimation and its design time reduction is achieved by means of an efficient hardware design using spatial segmentation methods and verification techniques. Finally we develop a system which can be used for embedded systems using a sound codec and an FPGA chip. According to experimental results, the system gives much faster real-time processing time compared with either PC-based systems or the case with DSP processors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.713-720
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• 2012

Recently, holography has received much attention as the next generation visual technology. Hologram is obtained by the optical capturing, but in recent years it is mainly produced by the method using computer. This method is named by computer generated hologram (CGH). Since CGH requires huge computational amount, if it is implemented by S/W it can't work in real time. Therefore it should use FPGA or GPU for real time operation. If it is implemented in the type of H/W, it can't obtain the same quality as S/W due to the bit limitation of the internal system. In this paper, we analyze the bit width for minimizing the degradation of the hologram and reducing more hardware resources and propose guidelines for H/W implementation of CGH. To do this, we performs fixed-points simulations according to main internal variables and arithmetics, analyze the numerical and visual results, and present the optimal bit width according to application fields.

• Journal of the Korea Furniture Society
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• v.18 no.2
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• pp.91-99
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• 2007

Modernity which is superficial phenomenon set off the mass scale for mass consumption and provide uniformly artificial environment. But natural destruction, environment pollution, resources exhaustion and so on has been caused by this and now ecology is threatened by destruction and damage beyond the limitation and human beings survival is even threatened. Accordingly furniture development for environment preservation considered environment problem is the urgent real situation. Recent paradigm is the concept of Eco-design which is the green design possible to live together in symbiosis, and new types of alternative furniture are needed in Korea as well. 'Furniture for disassembly' is presented as new method for alternative furniture. Furniture for disassembly can be presented by mainly two directions. The first main characteristic is what is assembled by the use of woodworking joints technique as an assembly structure system without any hardware. The second is what is presented as the structure possible to be assembled by simple manual tools with hardware without any glue. The advantages of furniture for disassembly are environment preservation, space application, transportation efficiency and shapeliness. In manufacture method which is different from present furniture, the application of traditional truss technique which uses various types of custom-made and connection technique in case of assemble structure system without hardware is the typical differences. This assembly method expects not only interest induction about assembly and disassembly of diagram per sub materials but also the development of emotion, the improvement of collaboration, space perception ability and shape sense, the improvement of solid body structure insight and so on, when it use in the furniture for children with the application to many kinds of structure with BANGDOOSANJ (Wedged), JUMUGJANGBU (Dovetail) or NABIEUNJANG (Dovetail Keys) and so on.