• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.469-471
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• 2002

This paper presents analysis of the IEEE802.11 MAC protocol and implementation of the asynchronous communication portion of the IEEE802.11 MAC protocol. we have used PRISM2 chipsets from intertsil to build physical layer and PCI controller from PLX to interface LLC layer. This study is shown to be able to apply to MAC implementation in high speed LAN.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.323-326
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• 2001

DTV 방송 신호를 수신하거나 송신하는 장비의 경우 대부분 한두 가지 인터페이스 방식을 이용하여 서로 통신을 하고 있다. 따라서 서로 다른 인터페이스 포맷을 사용하여 스트림을 전송하는 경우 기존의 장비를 사용하지 못하는 경우가 많이 있다. 본 논문에서는 이런 장비들 사이에서 주고받는 스트림의 포맷을 자유로이 연결 가능하도록 해주는 인터페이스를 설계 및 구현하였다. 본 논문에서 구현한 인터페이스는 스트림 자체 내용은 변경하지 않고, 송·수신하기 위한 인터페이스 규격에 스트림을 적용하여 자유로이 송·수신할 수 있도록 하였다. 구현한 인터페이스 규격은 SMPTE 310M, ASI(Asynchronous Serial Inerface), SPI (Synchronous Parallel Interface)와 셋탑박스에서 사용하는 TS(Transport Stream)의 네 가지로 서로간에 송·수신 가능하도록 매트릭스 형태를 취하고 있다. 주요 블록은 YHDL 코딩을 이용하여 설계를 하였으며, FPGA(EPF10K10T144)를 사용하였다.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.2
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• pp.93-99
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• 2011

In this paper, an ATSC(Advanced Television Standard Committee)-M/H(Mobile/Handheld) multiplexer is designed and implemented using an embedded Linux based hardware platform. The ATSC-M/H multiplexer is composed of a CPU(Central Processor Unit), an FPGA(Field-Programmable Gate Array), ASI(Asynchronous Serial Interface)/SMPTE310(Society of Motion Picture and Television Engineers310) interface board, and a GPS(Global Position System) clock processing block. The main functions of the ATSC-M/H multiplexer executed in the CPU and FPGA are described. The operation of the ATSC-M/H multiplexer is verified by processing its broadcast signal on a commercial receiver analyzer.

• KIISE Transactions on Computing Practices
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• v.24 no.3
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• pp.129-137
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• 2018

NVMe(Non-Volatile Memory Express) SSD(Solid State Drive) is a high-performance storage that makes use of flash memory as a storage cell, PCIe as an interface and NVMe as a protocol on the interface. It supports multiple I/O queues which makes it feasible to process parallel-I/Os on multi-core environments and to provide higher bandwidth than SATA SSDs. Hence, NVMe SSD is considered as a next generation-storage for data-center and cloud computing system. However, in the virtualization system, the performance of NVMe SSD is not fully utilized due to the bottleneck of the software I/O stack. Especially, when it uses I/O stack of the hypervisor or the host operating system like Xen and KVM, I/O performance degrades seriously due to doubled-I/O stack between host and virtual machine. In this paper, we propose a new I/O engine, called Direct-AIO (Direct-Asynchronous I/O) engine, that can access NVMe SSD directly for I/O performance improvements on QEMU emulator. We develop our proposed I/O engine and analyze I/O performance differences between the existed I/O engine and Direct-AIO engine.

• The KIPS Transactions:PartD
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• v.17D no.1
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• pp.9-16
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• 2010

Web service mashup bacomes one of the important web application development methods. This paper considers a client based mashup, where a page interfaces many service methods asynchronously. Browser systems execute callbacks when the corresponding reply arrives, possibly concurrent to user interface actions. In this case, callbacks and user interface actions share data memory and screen. Moreover, when the user is able to send another request before the previous ones have replied, the shared resource problem becomes more complicated. In order to solve the multiple requests problem, our contributions are as follows. First, we modeled a mashup page with user actions and callbacks, and we presented several types of callbacks. Secondly, concurrency condition is defined between callbacks and user actions in terms of shared resources, and the test method is presented. Also, we proposed the serialization approach to guarantee the safe execution of callbacks. Finally, we applied the proposed concurrency condition on XForms language and extended the XForms browser to implement the proposed approach. The prototype implementation showed that the proposed approach helps enhancing user experience on mashup pages.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.71-81
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• 2008

In this paper, we propose a novel Globally Asynchronous, Locally Dynamic System(GALDS) bus and demonstrate its performance. The proposed GALDS bus is the bidirectional multitasking bus with the segmented bus architecture supporting the concurrent operation of multi-masters and multi-slaves. By analyzing system tasks, the bus architecture chooses the optimal frequency for each If among multiples of bus frequency and thus we can reduce the overall power consumption. For efficient data communications between IPs operating in different frequencies, we designed an asynchronous and bidirectional FIFO based on an asynchronous wrapper with hand-shaking interface. In addition, since systems can be easily expandable by inserting bus segments, the proposed architecture has advantages in IP reusability and structural flexibility As a test example, a four-segment bus haying four masters and four slaves were designed by using Verilog HDL. We demonstrate multitasking operations with read/write data transfers by simulation when the ratios of operation frequency are 1:1, 1:2, 1:4 and 1:8. The data transfer mode is a 16 burst increment mode compatible with Advanced Microcontroller Bus Architecture(AMBA). The maximum operation latency of the proposed GALDS bus is 22 clock cycles for the bus write operation, and 44 clock cycles for read.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1057-1065
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• 2011

In order to achieve the ease of development and to facilitate the maintenance of codes for complex Ajax (Asynchronous Java Script and XML)-based web clients, this paper proposes a CVC (Communicator-View-Controller) architecture pattern by modifying the well-known MVC (Model-View-Controller) framework. By composing the Communicator of codes for asynchronous data retrieval, which is common to Ajax-based clients, the proposed architecture pattern is able to cut out the graphic design related codes to constitute the View layer. Based on such declarative generalization of complex web-client codes, Ajax-related codes can be easily modularized and efficiently reused in development and maintenance stages, and graphics design can be done separately regardless of the other business logic related codes development, resulting in highly efficient development and maintenance of complex Ajax-based web clients.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1196-1204
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• 2001

In this paper, a new architecture of operating software associated with the component-based method is proposed. The proposed architecture comprises 문 execution module and a decision-making module. In order to make effective development and maintenance, the execution module is divided into three components. The components are referred to as Symbol, Gateway, and Control, respectively: The symbol component is for the GUI environments and the standard interfaces; the gateway component is for the network communication and the structure of asynchronous processes; the control component is for the asynchronous processing and machine setting or operations. In order to verify the proposed architecture, and off-line version of operating software is made, and its steps are as follows; I) Make virtual execution modules for the manufacturing devices such as dual-arm robot, handling robot, CNC, and sensor; ii) Make decision-making module; iii) Integrate the modules and GUI using a well-known development tools such as Microsofts Visual Basic; iv) Execute the overall operating software to validate the proposed architecture. The proposed software architecture in this paper has the advantages such as independent development of each module, easy development of network communication, and distributed processing of resources, and so on.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.391-400
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• 2017

Geo-based application services linked with the Open Geospatial Consortium (OGC) Web Processing Service (WPS) protocol have been regarded as an important standardized framework for of digital earth building in the web environments. The WPS protocol provides interface standards for analysis functionalities within geo-spatial processing in web-based service systems. Despite its significance, there is few performance tests of WPS applications. The main motivation in this study is to perform the comparative performance test on WPS standards. Test system, which was composed of WPS servers, WPS framework, data management module, geo-based data processing module and client-sided system, was implemented by fully open source stack. In this system, two kinds of geo-based image processing functions such as cloud detection and gradient magnitude computation were applied. The performance test of different server environments of non-WPS, synchronous WPS 1.0 and asynchronous WPS 2.0 was carried out using 100 threads and 400 threads corresponds client users on a web-based application service. As the result, at 100 threads, performance of three environments was within an adjacent range in the average response time to complete the processing of each thread. At 400 threads, the application case of WPS 2.0 showed the distinguished characteristics for higher performance in the response time than the small threads cases. It is thought that WPS 2.0 contributes to settlement of without performance problems such as time delay or thread accumulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.185-194
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• 2008

In this paper, an efficient technique is proposed to integrate the 3D user interface with the tiled display system in PC cluster environment. In the developed 3D user interface software, various menus are provided to increase the user friendliness of the interface, including the several model-control-commands. To eliminate the noise produced from the 3D user interface devices, the box filtering algorithm is employed. Further, a communication splitting algorithm, which is a kind of asynchronous communication method, is proposed to reduce the motion delay between the 3D interface and the tiled display system, and its efficiency is validated through the benchmarking tests.