• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.105-108
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• 2001

4 32-bit RISC core is designed for embedded application and DSP. This processor offers low power consumption by fully static operation and compact code size by efficient instruction set. Processor performance is improved by wing conditional instruction execution, block data transfer instruction, multiplication instruction, bunked register file structure. To support compact code size of embedded application, It is capable cf executing both 16-bit instructions and 32-bit instruction through mixed mode instruction conversion Furthermore, for fast MAC operation for DSP applications, the processor has a dedicated hardware multiplier, which can complete a 32-bit by 32-bit integer multiplication within seven clock cycles. These result in high instruction throughput and real-time interrupt response. This chip is implemented with 0.35${\mu}{\textrm}{m}$, 4- metal CMOS technology and consists of about 50K gate equivalents.

• Journal of IKEEE
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• v.22 no.3
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• pp.878-881
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• 2018

In this paper, experiments through performance evaluation under real operation environment were conducted. Transceiver and microcontroller shows the characteristics for the amount of current consumption and software protocol was optimized by controlling the time of Report Attribute and electric current level. To reduce current consumption when using battery, with designing transmission of the same amount of data as soon as possible, power consumption efficiency was enhanced.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.415-420
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• 2006

IEEE 802.16은 높은 성능의 광대역 무선 통신을 제공해 주기 위해 개발된 자원 예약 방식의 MAC 프로토콜이다. 전송할 데이터를 가지고 있는 SS들은 BS에게 대역폭 요청 메시지를 전송하여 자신이 필요한 대역폭을 요구하게 된다. BS에서는 이러한 대역폭 요구 정보를 기반으로 대역폭을 할당해 주게 된다. 그러나, nrtPS와 BE 트래픽과 같은 비실시간 서비스들이 경쟁 기반으로 대역폭을 요구하는 경우 경쟁하는 SS의 수가 증가할수록 대역폭 요청 메시지의 충돌 확률이 증가하므로 이로 인해 대역폭 요구를 실패하는 횟수가 증가한다. 최악의 경우, 충분한 대역폭이 남아 있음에도 불구하고 대역폭 요구 과정의 실패로 인해 할당해주지 못하여 대역폭을 낭비하는 현상이 발생하게 된다. 본 논문에서는 네트워크 상황에 따라 경쟁 기반과 비경쟁 기반의 대역폭 요구 방법을 적절히 사용하는 효율적인 대역폭 요청 기법을 제안하고, 실험을 통해 높은 성능 향상을 입증한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.505-507
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• 2004

IEEE 802.11 무선랜 표준에서 MAC(Media Access Control)은 동기와 비동기의 두 가지 타입의 서비스를 지원한다. 동기적 실시간 트래픽은 PCF(Point Coordination Function)에 의해서 폴링 엑세스 기법에 의해 처리된다. 비동기적 비실시간 트래픽은 CSMA/CA 프로토콜 기반의 DCF(Distributed Coordination function)에 의해 처리된다. 그래서 실시간 트래픽은 지연과 패킷손실에 민감하고 비실시간 트래픽은 에러와 처리율에 민감하기 때문에 적당한 트래픽 스케줄링 알고리즘이 설계되어질 필요가 있다. 하지만 IEEE 802.11 무선랜 표준은 실시간 트래픽을 효율적으로 서비스를 해주지 못하고 있다. 그래서 본 논문에서는 PCF 구간내에서 서비스를 받지 못한 실시간 트래픽 스테이션들을 DCF 구간에서 우선적으로 서비스함으로써 QoS를 향상시킬 수 있다.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1052-1054
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• 2003

RAZAKSAT is a second micro-satellite mission by Malaysian Satellite Program and is expected for launch in June 2004. Designed to orbit the earth at low-equatorial orbit, RAZAKSAT will meet Malaysia’s immediate needs to rapid data acquisition (real time and more repetitions) to address many operational issues of remote sensing applications, which require availability of current data sets. RAZAKSAT will be among the first remote sensing satellite to orbit the earth at low inclination along the equator, 9$^{\circ}$ with 685km altitude, hence, allows optimal geographical information and environment change within equatorial region be observed with a unique revisit characteristics. The satellite primary payload is MAC, a push-broom type camera with 2.5m of ground sampling distance (GSD) in panchromatic band and 5m of GSD in four multi-spectral bands. This paper describes on the variation of illumination anticipated from simulated RAZAKSAT image, examine its implication to its ground leaving radiances for major applications.

• Annual Conference of KIPS
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• 2011.11a
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• pp.322-325
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• 2011

스테레오 비전 시스템에서 전통적인 매칭 알고리즘으로 SAD(Sum of Absolute Differences), SSD(Sum of Squared Differences), NCC(Normalized Cross Correlation) 등 다양한 알고리즘이 존재한다. 그러나 하드웨어로 실시간 처리를 위한 시스템을 구현하기 위해서는 리소스가 한정 되어있다는 제약 때문에 많은 연구에서 SAD 혹은 RT(Rank Transform), CT(Census Transform)를 많이 사용하게 된다. FPGA 내부에는 BRAM(Block RAM)과 MAC(multiply-accumulator)인 DSP슬라이스가 이미 존재한다. 본 논문에서는 BRAM과 DSP로직을 활용해서 전통적인 매칭 알고리즘 중에서 연산기 사용이 가장 많은 NCC를 FPGA로 실시간 처리 가능한 하드웨어 구조를 제안한다.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• Journal of Internet Technology
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• v.20 no.1
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• pp.301-313
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• 2019

In this paper, we propose a new MAC protocol for Cognitive Radio (CR)-based IoT networks, called MSMA/CA. We extend the standard CSMA/CA, adopted in IEEE 802.11 WLANs, to the CR networks with the minimal modification since it works well in the real world. We resolve the classical hidden/exposed terminal problems by a variant of RTS/CTS mechanism and further, the hidden primary terminal problem by the mutual spectrum sensing at the transmitter and the receiver. We also modify the backoff process of CSMA/CA to incorporate the blocking of secondary transmitters, with the aim of protecting ongoing primary transmissions from aggressive secondary users. We analyze the throughput and delay of our proposed scheme using the Markov chain model on the backoff procedure, and verify its accuracy by simulations. Simulation results demonstrate that our protocol is suitable for IoT networks since the performance is insensitive to the number of users or devices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.336-339
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• 2011

In the RTLS(Real Time Location Based System), in case of existing a number of moving target, extremely complecated data flow is can be occurred. In the network where single gateway exists, various data which was collected from sensor node is transmitted along the simple route as time goes by. In case of multi-gateway configuration, the collected data is transmitted through diverse routes rather than simple route. This kind of data causes jams on nodes and this brings down the performance of the network. Different from existing studies, in this thesis, MAC (Media Access Control) protocol which minimizes data collision between nodes and guarantees QoS(Quality of Service) is suggested, in order to communicate efficiently in multi-gateway underwater sensor network environment. In the suggested protocol, source node which wants to transmit data makes a channel reservation to a number of destination node using a RTS packet. Source node reserves a channel without collision, by scheduling CTS response time using expected delay information from neighbor nodes. Once the reservation is made, source node transmit data packet without collision. This protocol analyzes/estimates the performance compared to a method provided from existing studies via simulation. As a results of the analysis, it was comfirmed that the suggested method has better performance, such as efficiency and delay.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.4
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• pp.283-290
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• 2022

In this study, an IoT inspection system that can be linked with a server was developed using a gas timer and ESP-01 Wi-Fi module installed on a gas valve in the home. The server environment of the gas leak IoT inspection system was installed with APM (Apache, PHP, MySQL) to collect gas pressure data by generation so that leakage checks could be performed. In order to control the gas leak IoT inspection system, the app inventory was used to manage the gas leak check value in real time. In addition, user convenience has been enhanced so that membership management, WiFi settings, and leakage check values can be checked through mobile apps. In order to manage subscribers by region, the user list was checked by logging in in in the administrator mode so that the information on whether or not the leak test was conducted and the results could be provided. In addition, when the user presses the gas leak check button, the pressure is automatically checked, and the measured value is stored in the server, and when a gas leak occurs, the leakage check is performed after alarm and repair so that it can be used if normal. In addition, in order to prevent overlapping membership, membership management can be performed based on MAC addresses.