• 한국진공학회지
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• 제12권1호
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• pp.7-15
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• 2003

스피닝 로터 게이지는 표준기관의 고진공 국제비교에 전달표준기로 상용되고 있으며, 고진공 국가표준기인 동적교정장치를 이용하여 스피닝 로터 게이지를 교정하였다. 교정 결과의 불확도를 국제표준화기구에서 권고한 A형 불확도, B형 불확도, 합성표준불확도, 확장불확도 등으로 구분하여 평가하는 방법을 제시하였다. 이 방법에 따라 평가한 스피닝 로터 게이지의 합성표준불확도는 $1.8007\times10^{-5}$ Pa ~$4.8422\times10^{-5}$ Pa 이었다.

• 한국철도학회논문집
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• 제8권1호
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• pp.101-109
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• 2005

Roller test rig is the test facility for acquiring the data related dynamic characteristics of rolling stocks handily. The test method using roller test rig could be convenient to Set information about hunting and others rather than using field test. However, adopting this method brings about the inconvenient calibration process for measured data. This kind of additional effort results from the difference of contact condition between field test and test roller rig. In this paper, the numerical approach is used to get the amount of calibration. The analysis results of the field test are compared with results of the roller test rig to know what kind of alternation happens according to the change of contact condition.

• Wind and Structures
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• 제15권4호
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• pp.285-299
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• 2012

This paper describes the development and calibration of a structural monitoring system installed in a 80 meters high steel wind tower supporting a 2.1 MW turbine Wind Class III IEC2a erected in the central part of Portugal. The several signals are measured at four different levels and include accelerations, strains on the tower wall and inside the connection bolts, inclinations and temperature. In order to correlate measurements with the wind velocity and direction and with the turbine operational parameters the corresponding signals are obtained directly from the turbine own monitoring system and are incorporated in the developed system. Results from the system calibration, the structural identification and the initial period of data acquisition are presented in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2372-2374
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• 2003

With 3-D vision measuring, camera calibration is necessary to calculate parameters accurately. Camera calibration was developed widely in two categories. The first establishes reference points in space, and the second uses a grid type frame and statistical method. But, the former has difficulty to setup reference points and the latter has low accuracy. In this paper we present an algorithm for camera calibration using perspective ratio of the grid type frame with different line widths. It can easily estimate camera calibration parameters such as focal length, scale factor, pose, orientations, and distance. But, radial lens distortion is not modeled. The advantage of this algorithm is that it can estimate the distance of the object. Also, the proposed camera calibration method is possible estimate distance in dynamic environment such as autonomous navigation. To validate proposed method, we set up the experiments with a frame on rotator at a distance of 1,2,3,4[m] from camera and rotate the frame from -60 to 60 degrees. Both computer simulation and real data have been used to test the proposed method and very good results have been obtained. We have investigated the distance error affected by scale factor or different line widths and experimentally found an average scale factor that includes the least distance error with each image. It advances camera calibration one more step from static environments to real world such as autonomous land vehicle use.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.398-401
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• 2006

Dual channel Radiometer for Earth and Atmospheric Monitoring (DREAM) is the main payload on Science and Technology SATellite-2 (STSAT-2) of Korea. DREAM is two-channel microwave radiometer with linear polarization, and operating at center frequencies of 23.8 GHz and 37 GHz. An equation for DREAM calibration is derived which accounts for losses and re-radiation in the microwave components of the radiometer due to physical temperature. This paper describes the radiometric calibration equation to get antenna temperature ($T_A$) from the measured output data. At lower altitude, the measured deep space temperature is contaminated by middle atmosphere and earth radiation. In this paper, we presented the detail mathematical formulation to find the altitude up to which cold source brightness temperature is not affected by earth and middle atmosphere radiation. The DREAMPFM data is used to calculate the performance parameters (linearity, sensitivity, dynamic range, and etc.) of the system.

• 한국정보통신학회논문지
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• 제12권10호
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• pp.1822-1829
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• 2008

항체가 정밀한 항법 정보를 얻기 위해서는 관성 센서의 초기 오차에 대한 보정이 매우 중요하다. 본 논문에서는 레이트 테이블과 고성능 센서를 기준 센서로 사용하여, 저급 MEMS 관성 센서 오차 보정에 따르는 비용과 효율성의 어려움을 극복하는 방법을 제안하였다. 초기 오차 보정 과정에서 기준 센서와 타겟 센서에 같은 동적 입력을 인가한 후 결과를 분석하였다. 실험 결과를 통해 제안된 초기 오차 보정 방법이 실제로 매우 효율적이며 유용함을 확인할 수 있었다.

• 한국군사과학기술학회지
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• 제4권1호
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• pp.155-169
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• 2001

In this paper, dynamic pressure is mainly generated in the closed chamber of gun when the propellant is fired and has exponential pressure motion. Dynamic pressure calibrator with positive step pressure was designed and manufactured to meet the calibration of piezoelectric high pressure transducers which are mainly used to measure dynamic pressure motion in the test of weapon systems. In addition, the results of Performance test and analysis of system uncertainty are provided.

• 한국정밀공학회지
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• 제12권12호
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• pp.64-71
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• 1995

This investigation evaluates dynamic fracture characteristics of two alloy steels (STD-11 and STS-3) and a gray cast iron (GC-30). The dynamic fracture toughness of crack initiation and some of the dynamic fracturing characteristics were evaluated by using the instrumented Charpy impact testing procedures. It was found from experimental results for three kinds of materials that inertia force is directly proportional to impact velocity. The duration time of inertia force was found to be constant regardless of impact velocities in steel specimens.

• Geomechanics and Engineering
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• 제28권2호
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• pp.107-116
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• 2022

The steady state of unsaturated soil takes a long time to achieve. The soil seepage behaviours and hydraulic properties depend highly on the wetting/drying rate. It is observed that the soil-water characteristic curve (SWCC) is dependent on the wetting/drying rate, which is known as the dynamic effect. The dynamic effect apparently influences the scanning curves and will substantially affect the seepage behavior. However, the previous models commonly ignore the dynamic effect and cannot quantitatively describe the hysteresis scanning loops under dynamic conditions. In this study, a dynamic hysteresis model for SWCC is proposed considering the dynamic change of contact angle and the moving of the contact line. The drying contact angle under dynamic condition is smaller than that under static condition, while the wetting contact angle under dynamic condition is larger than that under static condition. The dynamic contact angle is expressed as a function of the saturation rate according to the Laplace equation. The model is given by a differential equation, in which the slope of the scanning curve is related to the slope of the boundary curve by means of contact angle. Empirical models can simulate the boundary curves. Given the two boundary curves, the scanning curve can be well predicted. In this model, only two parameters are introduced to describe the dynamic effect. They can be easily obtained from the experiment, which facilitates the calibration of the model. The proposed model is verified by the experimental data recorded in the literature and is proved to be more convenient and effective.

• 대한교통학회지
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• 제26권4호
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• pp.205-215
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• 2008

1980년대 후반부터 선진외국에서 ITS 정책과 연구에 대해 관심을 갖기 시작한 이후 정적 노선배정(Static Traffic Assignment)의 현실 정책 응용에 한계에 직면하면서 동적노선배정(Dynamic Traffic Assignment)에 대한 연구가 초점을 받기 시작하였으며 그 결과 급속한 연구 발전이 있게 되었다. 본 연구에서는 현실적인 정책분석 가능성을 고려하여 노선선택행태(route choice behavior)는 거시적 모형이고, 차량의 네트워크 상 동적위치배정(dynamic network loading)은 미시적 모형 그리고 교통류는 단순화된 미시적 모형(microscopic model)이 적용된 시뮬레이션 기반의 Dynameq 프로그램을 활용한 연구를 수행하였다. 본 연구의 핵심 내용은 우리나라 전국 고속도로 네트워크와 동적 O/D자료로 동적노선배정 분석 한 결과인 추정치와 관측 링크 교통량과의 차이를 비교 검증하는 연구를 수행함으로써 모형의 현실적 정책분석 가능성에 대한 판단 기준을 제시하는 것이다. 이를 위하여 우리나라의 고속도로 체계에 있어 영업소에서 영업소 간의 동적 O/D자료가 TCS(Toll Collection System)자료를 통해 정확하게 확보할 수 있다는 점을 이용하였으며, 순수하게 동적노선배정 모형 자체의 현실적 묘사능력을 시간대별 관측 교통량과 비교 검증함으로써 정책응용 가능성을 확인하고자 한 것이다. 또한 동적노선배정 분석 예제로 버스전용차로 정책에 대한 동적 분석과 정책 효과를 분석하였다.