• Journal of Positioning, Navigation, and Timing
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• 제11권4호
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• pp.269-277
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• 2022

In this paper, we overview the system development status of the national maritime precise point positioning-real-time kinematic (PPP-RTK) service in Korea, also known as the Precise POsitioning and INTegrity monitoring (POINT) system. The development of the POINT service began in 2020, and the open service is scheduled to start in 2025. The architecture of the POINT system is composed of three provider-side facilities-a reference station, monitoring station, and central control station-and one user-side receiver platform. Here, we propose the detailed functionality of each component considering unidirectional broadcasting of augmentation data. To meet the centimeter-level user positioning accuracy in maritime coverage, new reference stations were installed. Each reference station operates with a dual receiver and dual antenna to reduce the risk of malfunctioning, which can deteriorate the availability of the POINT service. The initial experimental results of a testbed from corrections generated from the testbed network, including newly installed reference stations, are presented. The results show that the horizontal and vertical accuracies satisfy 2.63 cm and 5.77 cm, respectively. For the purpose of (near) real-time broadcasting of POINT correction data, we designed a correction message format including satellite orbit, satellite clock, satellite signal bias, ionospheric delay, tropospheric delay, and coordinate transformation parameters. The (near) real-time experimental setup utilizing (near) real-time processing of testbed network data and the designed message format are proposed for future testing and verification of the system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.45-48
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• 2008

The mechanical behavior of small-sized materials has been investigated for many industrial applications, including MEMS and semiconductors. It is challenging to obtain accurate mechanical properties measurements for thin films due to several technical difficulties, including measurement of strain, specimen alignment, and fabrication. In this work, we used the micro-tensile testing unit with the real-time DIC (Digital Image Correlation) strain measurement system. This system has advantages of real time strain monitoring up to 50 nm resolution during the micro-tensile test, and ability to measure the young's modulus and Poisson's ratio at the same time. The mechanical properties of SCS (Single Crystal Silicon) are measured by uniaxial tension test from freestanding SCS which are $2.5{\mu}m$ thick, $200-500{\mu}m$ wide specimens on the (100) plane. Young's modulus, Poisson's ratio and tensile strength in the <110> direction are measured by micro-tensile testing system.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.1097-1108
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• 2022

This paper aimed to design and implement an EMS for real-time power generation control based on wake effect optimization of wind farm, and then to test it in commercial operating wind farm. For real-time control, we proposed the wake band-based optimization and setting the wake effect distance limit, and when the wake effect distance limit was set to 7D in the actual wind farm layout, the calculation time was improved by about 93.94%. In addition, we designed and implemented the script-based EMS for flexible operation logic management in preparation for unexpected issues during testing, and it was installed and tested on a wind farm in commercial operation. However, three issues arose during the testing process. These are the communication interface problem of meteorological tower, the problem of an abnormal wake effect, and the problem of wind turbine yaw control. These issues were solved by modifying the operation logic using EMS's script editor, and the test was successfully completed in the wind farm in commercial operation.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.37-43
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• 2005

A haptic steering system which reflects steering reaction torque has been developed for a fixed base vehicle simulator. The haptic steering system consists of a steering effort sensor, MR-clutch, AC servo motor and controller. In order to generate realistic steering torque feel to driver and at the same time to meet real-time simulation requirement, 3D torque map is constructed by experimental data and torque generation algorithm using the torque map has been also developed. 3D torque map is constructed using curve fitting and interpolation of the measured values of the steering angle, velocity and steering torque from actual slalom test on the proving ground. In order to carry out performance test of the developed haptic steering system, a fixed based vehicle simulator is constructed by integrating real time vehicle dynamics module, VR-video/audio module, and the haptic steering system. Steering torque and steering angle curves have been obtained from virtual testing in the vehicle simulator and performance of the haptic steering system has been evaluated.

• 비파괴검사학회지
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• 제30권3호
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• pp.212-224
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• 2010

The usefulness of the magnetic camera for non-destructive testing of aging aircraft is discussed in this paper. The magnetic camera can be used f magnetic particle testing(MT), magnetic flux leakage testing(MFLT), eddy current testing(ECT) and penetration testing(PT). It measures the distribution of a magnetic field and visualizes the magnetic pattern. Near and far side cracks, fatigue, thickness degradation, and cracks under rivets have been detected. The possibility of quantitative evaluation was also examined. Using indirect experiments, we verified the detection ability of the sensor for cracks in titanium and advanced composite materials.

• 항공우주시스템공학회지
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• 제10권1호
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• pp.29-34
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• 2016

Flutter wind-tunnel test is an expensive and complicated process. Also, the test model may has discrepancy in the structural characteristics when compared to those of the real model. "Dry Wind-Tunnel" (DWT) is an innovative testing system which consists of the ground vibration test (GVT) hardware system and software which computationally can be operated and feedback in real-time to yield rapidly the unsteady aerodynamic forces. In this paper, we study on the aerodynamic forces of DWT system to feedback in time domain. The aerodynamic forces in the reduced-frequency domain are approximated by Minimum-state approximation. And we present a state-space equation of the aerodynamic forces. With the two simulation model, we compare the results of the flutter analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.63-66
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• 1992

This paper presents the real time digital differential protection scheme for transformer. Inrush and Internal fault conditions are distinguished by the relative magnitudes of fundamental and second harmonic components which are extracted from differential currents. The algorithm is simulated and implemented using a prototype relay which is made up of Intel 80286 CPU and Motorola DSP-56001. The testing data of inrush and Internal fault signals which are sampled at a rate of 12 times a cycle are obtained by EMTP, and tested In real time using simulator which downloaded those data.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제8권4호
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• pp.137-144
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• 2019

무기체계 기술의 국산화 과정에서 경험과 기술이 부족한 상태로 개발 중인 체계에 대한 테스트 기술의 성숙도는 매우 중요하다. 테스트에서 발견하지 못한 결함은 시스템 운용 중 막대한 영향을 미친다. 잠수함에서 실시간 정보공유 체계는 신속한 지휘결심과 임무능력으로 이어진다. 데이터 분산 시스템은 매우 중요한 정보 공유체계이며 제조사나 데이터 형태가 다른 체계들 간에 이루어진다. 본 논문에서는 데이터 분산 시스템의 데이터 분산 특성을 분석하여 데이터별 체계를 그룹핑하고, 경로 테스트 기법에 트리순회 방법인 후위트리순회, 전위트리순회를 이용하여 테스트케이스 생성기법을 제시한다. 제시한 기법은 기존기법들에 비해 73.7% 테스팅 리소스를 감소시킬 수 있다.

• 비파괴검사학회지
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• 제32권3호
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• pp.291-295
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• 2012

In the industrial field, real-time monitoring system like a fault early detection is very important. For this, the infrared thermography technique as a new diagnosis method is proposed. This study is focused on the damage detection and temperature characteristic analysis of ball bearing using the non-destructive infrared thermography method. In this paper, thermal image and temperature data were measured by a Cedip Silver 450 M infrared camera. Based on the results, the temperature characteristics under the conditions of normal, loss lubrication, damage, dynamic loading, and damage under loading were analyzed. It was confirmed that the infrared technique is very useful for the detection of the bearing damage.

• 한국지진공학회논문집
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• 제10권5호
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• pp.99-106
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• 2006

이 논문에서 소개되는 실시간 하이브리드 실험 시스템은 유사동적실험법을 근거로 하고 있으며, 실제 실험과수학적 모델을 이용한 수치해석을 결합한 실험법이다. 이 시스템은 종래의 유사동적해석법에 비해 지진하중을 받는 구조물의 실시간 반응에 근접하는 현저히 높은 하중재하 속도를 고려할 수 있도록 설계되었다. 또한 다자유도 구조물에 대해 안정적인 해석환경을 제공하기 위해 이 시스템은 implicit 시간적분법을 이용하여 수치해석을 수행한다. 이 논문은 연구를 통해 개발된 시스템의 전반적인 개요와 구성요소 그리고 이 시스템에서 사용하는 수치 해석법의 성능을 평가하기 위해 수행된 수치해석을 소개한다. 연구 결과 개발된 시스템에 적용된 수치해석법은 성능이 매우 우수하다는 것이 증명되었다.