• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.624-633
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• 2018

While the multimedia lecture system has been getting smart using immerging technology, the microphone still relies on the classical approach such as holding in hand or attaching on the body. In this paper, we propose a ceiling mounted array microphone system that allows a wide reception coverage and instructors to move freely without attaching microphone. The proposed system adopts cell and handover of mobile communication instead of a complicated beamforming method and implements a wide range microphone over several cells with low cost. Since the characteristics of unvoiced speech is similar to Pseudo Noise it is shown that soft handover are possible with 3 microphones connected to delay-sum multipath receiver. The proposed system is tested in $6.3{\times}1.5m$ area. For real-time processing the correlation range can be reduced by 82% or more, and the output latency delay can be improved by using the delay adaptive filter.

• The KIPS Transactions:PartA
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• v.13A no.3 s.100
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• pp.191-198
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• 2006

Today's portable electric consumer devices, which are operated by battery, tend to integrate more multimedia processing capabilities. In the multimedia processing devices, multimedia system-on-chips can handle specific algorithms which need intensive processing capabilities and significant power consumption. As a result, the power-efficiency of multimedia processing devices becomes important increasingly. In this paper, we propose a reconfigurable data caching architecture, in which data allocation is constrained by software support, and evaluate its performance and power efficiency. Comparing with conventional cache architectures, power consumption can be reduced significantly, while miss rate of the proposed architecture is very similar to that of the conventional caches. The reduction of power consumption for the reconfigurable data cache architecture shows 33.2%, 53.3%, and 70.4%, when compared with direct-mapped, 2-way, and 4-way caches respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2189-2196
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• 2015

According to increase environmental pollutions and fuel costs, The study of energy saving in the ship is proceeding actively. PCS is pump control system for cooling system in the ship to improve the energy efficiency by controling rotation speed of sea water pump, fresh water pump and position of 3way valve. In this paper, we develop the PCS simulator that has an environment similar to the cooling system of the actual vessel to ensure reliability of the PCS. Also, PC-based control and data storage system for PCS simulator is developed. To develop this system, National Instrument's cDAQ and LabVIEW are used. Finally, confirm the behavior of the simulator by analyzing the saving data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.57-66
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• 2001

This paper resents a control approach for designing a fuzzy-PI controller for a synchronous generator excitation and SVC system A combination of thyristor-controlled reactors and fixed capacitors (TCR-FC) type SVC is recognized as having the must fiexible control and high speed response, which has been widely utilized in power systems, is considered and designed to improve the response of a synchronous generator, as well as controlling the system voltage A Fuzzy-PI controller for SVC system was proposed in this paper. The PI gain parameters of the proposed Fuzzy-PI controller which is a special type of PI ones are self-tuned by fuzzy inference technique. It is natural that the fuzzy inference technique should be barred on humans intuitions and empirical knowledge. Nonetheless, the conventional ones were not so. Therefore, In this paper, the fuzzy inference technique of PI gains using MMGM(Min Max Gravity Method) which is very similar to humans inference procedures, was presented and allied to the SVC system. The system dynamic responses are examined after applying all small disturbance condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.471-476
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• 2015

In this paper, we propose an energy efficient hybrid MAC protocol for multi-hop wireless sensor networks. The proposed MAC protocol used a hybrid mechanism, in which contention-based MAC protocol and contention free MAC protocol are combined. The sensor nodes located far from the sink node usually send few data packet since they try to send measured data by themselves. So contention-based MAC protocol is useful among them. But other nodes located near sink node usually have lots of data packets since they plays as a relay node. Contention-based MAC protocol among them is not suitable. Using contention-based MAC protocol in heavy data traffic environment, packet collisions and transmission delay may increase. In this paper, slot assignment between sender nodes by sink node is used. The proposed mechanism is efficient in energy and latency. Results showed that our MAC protocol outperformed other protocol in terms of data packet delivery delay and energy consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.265-272
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• 2011

This study designed and manufactured "a DVOR virtual signal generator" to make the monitoring system of preliminary Doppler VHF Omni-directional Radio Range(DVOR) run like its real operation status in a narrow space in order to study "a DVOR virtual monitoring system". The designed and manufactured DVOR virtual signal generator is suitable for the specification of signal that is generated in the currently running equipment. In addition, it is possible to control operation conditions of equipment by using parameter variables, and the circuit construction is largely divided into the input part, the modulation part, the high-gain amplifier, and the power part. "The DVOR virtual monitoring system using the virtual signal designed and implemented in this study is very suitable to be used for low-cost actual education as it can construct the operation status like the real situation in a narrow space without using an actual system like an antenna generating side band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1261-1266
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• 2009

In this paper, triple band mobile chip antenna for DCS(1.71${\sim}$1.88GHz) / PCS(1.75${\sim}$1.87GHz) / UPCS(1.8S${\sim}$1.99GHz) on PCB Layout is designed. To analyze the characteristics of the designed antenna, we used commerical simulation tool(HFSS). Triple and wide band characteristic could be realized the measured bandwidth(V.S.W.R<2.0) of the designed antenna operated in 1.71GHz${\sim}$1.99GHz. The size of the designed antenna is about 19mm${\times}$4mm${\times}$1.6mm, narrow bandwidth which is a defect of chip antenna is improved. And its experimental results were a good agreement with simulation performance.

• KIISE Transactions on Computing Practices
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• v.21 no.10
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• pp.639-644
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• 2015

The capacity of flash-based storage such as Solid State Drive(SSD) and embedded Multi Media Card(eMMC) is ever-increasing because of the needs from the end-users. However, if a flash-based storage crashes, such as during power failure, the flash translation layer(FTL) is responsible for the crash recovery based on the entire flash memory. The recovery time increases as the capacity of the flash-based storages increases. We propose O1FTL with O(1) crash recovery time that is independent of the flash capacity. O1FTL adopts the working area technique suggested for the flash file system and evaluates the design on a real hardware platform. The results show that O1FTL achieves a crash recovery time that is independent of the capacity and the overhead, in terms of I/O performance, and achieves a low P/E cycle.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.511-520
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• 2006

WebDAV is a protocol which supports web-based distributed authoring and versioning, providing a standard infrastructure for asynchronous collaboration on various contents through the Internet. Current WebDAV-enabled authoring applications that support WebDAV, such as Microsoft office, Photoshop, or Dreamweaver, work by integrating WebDAV capabilities into the application. While this approach provides solid support for collaborative authoring, it has a drawback that each of the applications needs to support WebDAV capabilities in its own way. We developed a WebDAV client named DAView running on Linux KDE, which enables WebDAV-unaware authoring tools to have effective remote authoring capabilities. DAView provides a GUI view of a WebDAV server, similar to existing WebDAV-enabled file managers such as DAVExplorer. Unique among WebDAV file managers, it also provides the ability to launch the authoring application associated to a WebDAV server resource, automatically managing the locks on the resource.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.10
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• pp.487-492
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• 2017

Clustering is a technique which is used to measure similarities between data in big data analysis and data mining field. Among various clustering methods, k-Modes algorithm is representatively used for categorical data. To increase the performance of iterative-centric tasks such as k-Modes, a distributed and concurrent framework Spark has been received great attention recently because it overcomes the limitation of Hadoop. Spark provides an environment that can process large amount of data in main memory using the concept of abstract objects called RDD. Spark provides Mllib, a dedicated library for machine learning, but Mllib only includes k-means that can process only continuous data, so there is a limitation that categorical data processing is impossible. In this paper, we design RDD for k-Modes algorithm for categorical data clustering in spark environment and implement an algorithm that can operate effectively. Experiments show that the proposed algorithm increases linearly in the spark environment.