• Ocean Systems Engineering
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• 제7권2호
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• pp.121-141
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• 2017

The purpose of this paper is to understand and model the slow current (~2 m/s) effects on the global response of a floating offshore platform in waves. A time-domain numerical simulation of full wave-current-body interaction by a quadratic boundary element method (QBEM) is applied to compute the hydrodynamic loads and motions of a floating body under the combined influence of waves and current. The study is performed in the context of linearized potential flow theory that is sufficient in understanding the leading-order current effect on the body motion. The numerical simulations are validated by quantitative comparisons of the hydrodynamic coefficients with the WAMIT prediction for a truncated vertical circular cylinder in the absence of current. It is found from the simulation results that the presence of current leads to a loss of symmetry in flow dynamics for a tension-leg platform (TLP) with symmetric geometry, resulting in the coupling of the heave motion with the surge and pitch motions. Moreover, the presence of current largely affects the wave excitation force and moment as well as the motion of the platform while it has a negligible influence on the added mass and damping coefficients. It is also found that the current effect is strongly correlated with the wavelength but not frequency of the wave field. The global motion of a floating body in the presence of a slow current at relatively small encounter wave frequencies can be satisfactorily approximated by the response of the body in the absence of current at the intrinsic frequency corresponding to the same wavelength as in the presence of current. This finding has a significant implication in the model test of global motions of offshore structures in ocean waves and currents.

• 방송공학회논문지
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• 제26권4호
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• pp.356-367
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• 2021

최근 사물인터넷 및 인공지능 기술의 발전에 따라 제조, 스마트시티 등 다양한 분야에서 실시간으로 데이터를 수집하고 분석하여 현실세계 문제에 대한 최적화를 수행하는 연구 및 적용사례가 증가하고 있다. 대표적으로 현실세계를 디지털화한 가상세계와 양방향으로 실시간 동기화를 지원하는 디지털 트윈 기술이 주목받고 있다. 본 논문에서는 디지털 트윈을 정의하고 사물인터넷 국제표준인 oneM2M 기반의 IoT 플랫폼을 활용하여 현실사물과 가상세계의 예측결과를 실시간으로 연결하는 디지털 트윈 플랫폼의 프로토타입을 제안한다. 또한, 제안된 프로토타입을 적용하여 물체의 충돌을 사전에 예측하여 사고를 예방할 수 있는 응용서비스를 구현한다. 응용서비스에서는 사전 정의한 테스트 케이스 수행을 통해 제안한 디지털 트윈 프로토타입이 크레인의 동작을 사전 예측하여 충돌 위험을 감지하고 이를 기반으로 최적 제어를 수행할 수 있으며 실제 환경에 응용 가능함을 보였다.

• ETRI Journal
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• 제30권1호
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• pp.129-140
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• 2008

In this paper, we propose a novel ant colony optimization (ACO)-based test scheduling method for testing network-on-chip (NoC)-based systems-on-chip (SoCs), on the assumption that the test platform, including specific methods and configurations such as test packet routing, generation, and absorption, is installed. The ACO metaheuristic model, inspired by the ant's foraging behavior, can autonomously find better results by exploring more solution space. The proposed method efficiently combines the rectangle packing method with ACO and improves the scheduling results by dynamically choosing the test-access-mechanism widths for cores and changing the testing orders. The power dissipation and variable test clock mode are also considered. Experimental results using ITC'02 benchmark circuits show that the proposed algorithm can efficiently reduce overall test time. Moreover, the computation time of the algorithm is less than a few seconds in most cases.

• 전기전자학회논문지
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• 제28권3호
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• pp.310-320
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• 2024

본 논문에서는 5G-NR-V2X 시스템과 그 통신 성능 분석 방법론에 관해 설명한다. 자율 주행 서비스(레벨 4 이상)를 개발하고 성능을 검증할 수 있는 시스템을 제시하며, OBU 및 RSU를 사용한 실제 도로 시험 환경에서 5G-NR-V2X 통신을 통해 성능을 검증한다. 이 시스템은 초고속(150Mbps 이상), 초저지연(3ms 이하), 높은 신뢰성(99.99% 이상)을 만족시키며, 악의적인 조건에서도 통신 견고성을 유지한다. 본 논문에서 제안하는 5G-NR-V2X 시스템 및 성능 분석 방법은 초고속, 초저지연, 고신뢰의 V2X 통신 기술 개발에 기여할 것으로 기대된다. 또한, 제안된 성능 분석 기법을 통해 검증된 서비스는 도로, 교통, 물류 및 상업 산업에서 기술 경쟁력을 강화할 것으로 예상된다.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1244-1252
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• 2008

This paper presents the analysis results obtained by the flight test of reconfiguration flight control system for an aircraft. The reconfiguration flight control system was designed by using control allocation scheme that automatically distributes the demanded control moments determined by control law to each actual control surface. In this paper, some control allocation algorithms for reconfiguration control of general aircraft with redundant control surfaces are summarized and their performance evaluation results through nonlinear simulation and Hardware-In-the-Loop-Simulation (HILS) test are shown. Also, Unmanned Aerial Vehicle (UAV) system adopted as a platform for the flight test of reconfiguration flight controller and the implementation procedure of reconfiguration flight controller into real-time UAV system were introduced. Finally, flight test results were analyzed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1671-1674
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• 2007

A PSD system has a lot of characteristic for safety. Trust of performance test is very important. But PSD performance test has an effect on trust by proficiency of test staff because it is difficult to automate. In that specially the effort test, manual opening and shutting test and abrasion measurement, test staff is demanded for proficiency. Therefore the paper repeated measurement in same condition and studied proficient factor of examiner according to increased measurement counter. As a result, measurement uncertainty has improved.

• 한국해양공학회지
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• 제21권2호
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• pp.67-74
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• 2007

Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.

• 한국산학기술학회논문지
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• 제12권7호
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• pp.3220-3226
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• 2011

지하철 역사에 화재, 테러 등의 내 외부 위험요인을 감시하기 위하여 CCTV와 각종 센서를 이용한 감시시스템이 구축되어 왔으며, 최근 최신의 IT기술인 센서네트워크기술을 이용한 감시시스템기술 도입이 여러 분야에서 시도되고 있다. 2007년부터 정부 주도하에 지하철 역사의 경우에도 최신의 IT기술인 무선 센서네트워크기술 및 지능 형영상감시기술 등과 접목하여 화재, 제한지역 침입, 승객 혼잡도, 우범지역, 역사 건전성 등을 종합적으로 감시하는 도시철도지능형종합감시시스템 개발 및 구축이 추진 중에 있다. 이를 위하여 본 연구에서는 개발 중인 도시철도 지능형 종합감시시스템의 현장 역사 적용에 앞서 무선센서네트워크의 대표라 할 수 있는 ZigBee기반의 현장 무선통신환경 시험을 서울지하철 충무로 역사에서 수행하였고, 본 논문에 충무로역사 내부 승강장 및 대합실에서의 ZigBee기반의 무선통신환경 시험결과를 정리, 분석하였다. 승강장 및 대합실의 무선 스펙트럼분석 결과 ZigBee기반의 센서네트워크의 주파수와 중첩되는 주파수는 없었으며 인접 주파수 또한 10MHz 이상 이격되어 주파수 간섭을 받지 않는 것으로 나타났다. ZigBee를 이용한 무선데이터 전송 시험 결과, 데이터 전송은 열차의 승강장 진출입시의 영향보다 승강장 혹은 대합실의 이용승객 수 및 유동량에 의한 멀티패스 페이딩(multi-path fading) 효과에 더 큰 영향을 받는 것으로 나타나, 역사에 지능형종합감시시스템 구축 시 이를 고려하여야 할 것으로 판단된다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.462-465
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• 2009

모바일 응용 S/W GUI를 기존의 매뉴얼을 보고 테스트 하는 단계적이고 수동적인 방법을 탈피하여 사용자 중심의 시나리오를 통하여 자동으로 GUI를 테스트 하는 것을 목적으로 한다. 제시한 테스트 방법은 사용자 중심의 UI를 설계하여 간편하고, 정확하게 테스트 할 뿐만 아니라 테스트케이스를 재사용하는 환경을 지원한다. 제안한 자동화 도구는 시나리오 기반의 정확한 테스트와 재사용성을 높인 테스트 도구로서 기존 테스트 도구와 기능적인 비교를 통하여 성능을 확인하였다.

• 한국전문물리치료학회지
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• 제3권3호
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• pp.1-11
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• 1996

The purpose of this study were to evaluate and compare the balance ability at different conditions in normal 20 to 29 years old on unstable platform, KAT 2000(Breg, Inc., Vista, CA. 1994). Static and dynamic BI(balance index) were measured 3psi and 5psi surface conditions. Static tests were done on right and left leg separately, then both legs together with the feet apart 20cm with the eyes opened and closed. Dynamic tests were done on both legs together with apart 20cm with the eyes opened. A dynamic test was performed in which the subject moved platform in a circular manner to chase a moving object on a computer screen. Seventy healthy students(average 21.6 years, male, female) were tested. In this study applied the paired t-test and correlation to determine the statistical significance of result. The results were as follow: 1) The mean static balance index of the Rt leg was $119.9{\pm}75.72$ on 3psi surface condition with the eyes opened, and that of the Lt leg was $224.3{\pm}121.16$. 2) The mean static balance index of the Rt leg was $93.1{\pm}24.16$ on 5psi surface condition with the eyes opened, and that of the Lt leg was $180.5{\pm}61.76$. 3) The mean static and dynamic balance index of both legs were $76.4{\pm}31.86$, $2187.6{\pm}696.99$ on 3psi with the eyes opened, and $68.3{\pm}14.82$, $1938.7{\pm}525.41$ on 5psi respectively. 4) The mean static balance index of the Rt leg was $517.8{\pm}220.87$ on 3psi surface condition with the eyes closed, and that of the Lt leg was $588.6{\pm}204.81$. 5) The mean static balance index of the Rt leg was $271.9{\pm}192.151$ on 5psi surface condition with the eyes closed, and that of the Lt leg was $363.4{\pm}98.97$. 6) The mean static balance index of both legs was $332.6{\pm}137.31$ on 3psi surface condition with the eyes closed, and that of the 5psi was $288.5{\pm}133.07$. 7) The balance index on 3psi surface condition was significantly higher than that of 5psi (p<0.05, p<0.01). 8) The balance index with the eyes closed was significantly higher than that of the eyes opened (p<0.05). 9) The balance index on the left leg was significantly higher than that of the right leg (p<0.05, p<0.01). 10) There was no correlation between static balance index and dynamic balance index. 11) Therewas no correlation between weight or height and balance index.