• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2346-2349
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• 2005

Distributed Autonomous Robotic System (DARS) is defined as a system that independent autonomous robots in the restricted environments infer their status from pre-assigned conditions and operate their jobs through the cooperation with each other. In the DARS, a robot contains sensor part to percept the situation around themselves, communication part to exchange information, and actuator part to do a work. Especially, in order to cooperate with other robots, communicating with other robots is one of the essential elements. Because Bluetooth has many advantages such as low power consumption, small size module package, and various standard protocols, Bluetooth is rated as one of the efficient communicating technologies which can apply to small-sized robot system. In this paper, we will develop Bluetooth communicating system for autonomous robots such as DARS robots. For this purpose, The Bluetooth communication system must have several features. The first, this system should be separated from other robot parts and operate spontaneously and independently. In other words, this communication system should have the ability to organize and maintain and reorganize a network scheme. The next, this system had better support any kinds of standard interfaces in order to guarantee flexible applicability to other embedded system. We will discuss how to construct and what kind of procedure to develop the network system.

• 대한전자공학회논문지SD
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• 제41권11호
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• pp.105-113
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• 2004

기존의 3차원 그래픽 가속기는 전력소모 및 규모가 커서 휴대형 기기에는 적합하지 않다. 따라서 본 논문에서는 휴대형기기에 적합한 저전력 소규모의 3차원 렌더링 처리기를 제안한다. 소규모의 구현을 위하여 반복연산 및 고정소수점 연산을 사용하였다. 또 저전력의 고려를 위해 텍스쳐 유무에 따라 효율적으로 파이프라인을 관리하였고, 삼각형 셋업 및 에지워킹 단은 순차적으로, 3차원 영상 가속기의 성능을 좌우하는 스캔라인처리와 스팬처리 단은 병렬적으로 처리하게 설계하였다. 설계한 렌더링 처리기는 800*600의 해상도 지원과 32비트의 트루칼러를 지원하며 0.25㎛ ASIC공정에서는 50MHz로 동작하여 초당 47.88M 개의 픽셀과 33.25 프레임을 처리하며 텍스쳐 매핑을 포함 64만 게이트를 가지며 면적은 4.9827mm*4.9847mm 이이며 파워소모는 263.7mW이다.

• 한국인터넷방송통신학회논문지
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• 제12권4호
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• pp.141-145
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• 2012

유비쿼터스 센서 네트워크에서 센서노드는 일반적으로 크기가 소형이고 저가이며 배터리로 운용되므로 전력이 부족한 특징이 있다. 이런 센서 노드 환경에서 신뢰도가 높은 TCP/IP 프로토콜을 적용하여 센싱된 데이터를 전송하는 경우에 센서 노드에 내장된 메모리 크기의 제약을 극복하는 기술이 제안되었으나 오류가 발생하는 경우에 적용이 어려운 문제가 있었다. 본 논문에서는 이 문제를 극복하기 위해 프레임 오류나 손실 시에 처리하는 알고리즘이 제안되었으며, 주기적으로 센싱 데이터를 전송하는 일반적인 경우에 적용이 가능하다.

• 드라이브 ㆍ 컨트롤
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• 제15권1호
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• pp.10-15
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• 2018

The hydraulic cylinder seals are used not only to protect leakage of the working fluids but also to prevent incoming of foreign particles into the system. Chromium plating is generally applied to improve corrosion and wear resistance. It has been noticed that sealing surface damage occurs due to the hard foreign/wear particles contained in the hydraulic oil. In this study, a three-bodied sliding contact problem related with a PTFE seal, a spherical particle and chrome-plated steel substrate is modeled to investigate the relations to wear mechanism. Using the nonlinear finite element software, MARC/MENTAT, the deformed shapes, the von Mises and first principal stress distributions with plating thickness were compared. The sealing surface was mainly abraded by hard particles embedded in the seal. The plastic deformation of the steel substrate decreased with thicker plating. Hence it could be more effective to coat the sealing surface of a hydraulic cylinder with a hard material such as TiN, TiC and DLC.

• 대한전자공학회논문지SD
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• 제41권10호
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• pp.23-29
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• 2004

본 논문에서는 SRAM을 내장하는 시스템형 집적회로에서 싱글 포트 SRAM을 이용하여 듀얼 포트 SRAM으로 동작하는 구조를 제안한다. 외부 호스트는 내부 SRAM에 데이터를 자유로이 읽거나 쓸 수 있고, 내부 SRAM은 또 다른 외부의 회로부에 저장 데이터의 전달이 가능하면서 호스트와는 동기신호가 없는 구조 즉, 어싱크로너스 듀얼 포트 SRAM의 동작을 하는데, 싱글포트 SRAM을 이용하여 어싱크로너스 듀얼 포트로동작을 하도록 내부의 기능부를 설계하여 듀얼 포트 SRAM에 비해 적은 면적을 차지하는 구조를 제안하고 0.35um CMOS공정으로 칩을 제작하고 검증하였다. 결과로 20% 면적 감소와 20% 전력소비의 효과를 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제18권1호
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• pp.24-30
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• 2021

There is an increasing interest in condition-based maintenance for the prevention of economic loss due to failure. Moreover, immense research is being carried out in related technologies in the field of construction machinery. In particular, data-based failure diagnosis methods that employ AI (machine & deep learning) algorithms are in the spotlight. In this study, we have focused on the failure diagnosis and mode classification of reduction gear of excavator's travel device by using the AI algorithm. In addition, a remote monitoring system has been developed that can monitor the status of the reduction gear by using the developed diagnosis algorithm. The failure diagnosis algorithm was performed in the process of data acquisition of normal and abnormal under various operating conditions, data processing and analysis by the wavelet transformation, and learning. The developed algorithm was verified based on three-evaluation conditions. Finally, we have built a system that can check the status of the reduction gear of travel devices on the web using the Edge platform, which is embedded with the failure diagnosis algorithm and cloud.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.617-627
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• 2021

Underwater Acoustic Channels (UAC) have inherent sparse characteristics. The traditional adaptive equalization techniques do not utilize this feature to improve the performance. In this paper we consider the Variable Adaptive Subgradient Projection (V-ASPM) method to derive a new sparse equalization algorithm based on the Minimum Symbol Error Rate (MSER) criterion. Compared with the original MSER algorithm, our proposed scheme adds sparse matrix to the iterative formula, which can assign independent step-sizes to the equalizer taps. How to obtain such proper sparse matrix is also analyzed. On this basis, the selection scheme of the sparse matrix is obtained by combining the variable step-sizes and equalizer sparsity measure. We call the new algorithm Sparse-Control Proportional-MSER (SC-PMSER) equalizer. Finally, the proposed SC-PMSER equalizer is embedded into a turbo receiver, which perform turbo decoding, Digital Phase-Locked Loop (DPLL), time-reversal receiving and multi-reception diversity. Simulation and real-field experimental results show that the proposed algorithm has better performance in convergence speed and Bit Error Rate (BER).

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.29-35
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• 2022

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.866-872
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• 2024

Design Extension Conditions (DEC)-A assessments of the operating nuclear power plants are generally considered for the purpose of getting additional safety demonstrations of their capability to undergo conditions that are generally more severe than DBAs by features implemented in the design and accident management measures. The pursued methodology is generally based upon Best Estimate approaches aiming at verifying that the safety limits in terms of integrity of the barriers against eventual large or early releases of radioactive material are fulfilled. These aspects are nowadays being experimentally and analytically addressed within the OECD/NEA experimental projects like the ATLAS and PKL series where a set of DEC-A experiments are considered. In this paper, experiments related to SBLOCA at the vessel upper head of the pressurized vessel of ATLAS and PKL are analytically assessed using the CATHARE code. These experiments includes issues related to common cause failure of the safety injection system and operator actions for preventing core excessive overheating. It is shown that, on the one hand, the safety features embedded in the design together with the operator actions are capable to prevent the progression towards a severe accident state and on the other hand, the code prediction capabilities for such scenario are generally good but still to be enhanced.

• 전자공학회논문지CI
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• 제47권1호
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• pp.171-184
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• 2010

본 연구에서는 실시간 멀티미디어 서비스의 QoS를 향상시키기 위해 계층 통합 최적화 기법을 통한 새로운 파워 할당 기법을 소개한다. 각각의 패킷이 QoS에 미치는 영향이 다르므로, 항상 패킷 손실의 감소가 QoS의 향상으로 이어지지는 않는다. 본 연구에서는 패킷이 QoS에 미치는 영향을 정량화 하여 이를 바탕으로 파워를 할당하는 기법을 개발하였다. 다이내믹 프로그래밍 기법을 사용하여 파워소모를 최소화하면서 QoS를 극대화하는 적절한 파워 값을 발견하였으며, 실험을 위해 널리 공개된 비디오 클립을 사용하였다. 네트워크 시뮬레이터 (network simulator version 2)를 통하여 시뮬레이션을 수행하였으며, 성능 평가를 위해 클라이언트 단에 디코딩엔진을 삽입하여 원본 영상과 전송된 영상을 비교, PSNR을 도출하였다. 패킷 세만틱 정보를 기반으로 적절한 파워를 할당한 결과 기존의 기법에 비해 QoS가 크게 향상되는 것을 확인할 수 있었으며, 이는 본 논문에서 제안된 기법이 보다 중요한 패킷에 대한 차별적인 보호 기법이 적용된 결과임을 각 프레임 손실에 대한 조사로 알 수 있었다. 해당 기법의 적용을 통해 I 프레임의 경우 손실이 최대 29%에서 2%이내로 감소하는 것을 확인할 수 있었으며, 같은 결과를 나타낼 때, 파워 소모를 최대 약 20%까지 감소시키는 것을 확인할 수 있었다.