• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3488-3493
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• 2022

Accelerator driven subcritical systems have long been discussed as facilities which can be used for solving the nuclear waste problem. The physics of these systems is very different from conventional reactors and new techniques had to be developed for reactivity monitoring. One such technique is the Area Ratio Method which studies the response of a subcritical system upon insertion of a large number of neutron pulses. An issue associated with this technique is the spatial dependence of measured reactivity which is intrinsic to the sub criticality of the system since the reactor does not operate on the fundamental mode and measured reactivity depends on the detector position. This is generally addressed by defining Bell-Glasstone spatial correction factor. This factor upon multiplication with measured reactivity gives the correct reactivity which is independent of detector location. Monte Carlo Methods are used for evaluating these factors. This paper presents a complete three dimensional map of spatial correction factors for BRAHMMA subcritical system. In addition, the dataset obtained also helps in identifying detector locations where the correction factor is close to unity, thereby implying no correction if the detector is used at those locations.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.495-496
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• 2008

• 지구물리와물리탐사
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• 제5권3호
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• pp.145-149
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• 2002

정보정은 풍화층의 두께나 속도가 균질하지 않아 하부의 지층으로부터 전파된 신호의 왜곡을 보정하는 방법으로 굴절파에 근거한 정보정과 반사파에 근거한 잔여 정보정이 있다. 이 중 굴절파에 근거한 정보정은 일반적으로 분석자의 주관적인 해석에 의존하므로 많은 시간이 소요된다. 따라서 방대한 양의 자료를 처리해야하는 3차원 탄성파 탐사 자료의 정보정에 적용하는 데는 어려움이 있다. 이러한 굴절파에 근거한 정보정을 적용하기 위해서는 분석자의 해석을 최소한으로 하여 자동적으로 정보정을 수행하는 방법의 개발이 필요다. 본 연구에서는 굴절파에 근거한 정보정 방법을 육상 3차원 탄성파 탐사 자료에 대해 효과적으로 수행할 수 있는 방법에 대해 살펴보았다.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.57-63
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• 1999

A thin metal plate such as detent spring has the shape deformation due to the phenomenon of spring back after press machining and heat treatment process. This requires the correction of spring shape and force in final inspection process. To do correction of the shape deformation the impact force is manually applied to the bended part of detent spring after measuring the shape deformation and spring force. To develop the automatic spring force correction system, applied force of occurring plastic deformation must be derived from the experimental method. But frequent change of spring shape and material makes it difficult to accomplish the experimental method to be applied. This paper describes the analytical method for detent spring force correction system is to be substituted for the experimental method. FEM(Finite Element Method) is used to find the boundary value between elastic and plastic deformation in the analytical method. To confirm the validity of the analytical method, the result of two methods is compared each other at various applied force conditions. It shows that the simulation result of the analytical method is consistent with the result of the experimental method within the error bound ${\pm}$5%. The result of this paper is useful for development of the automatic spring correction system and reduction of the complicated and tedious processes involved in experimental method.

• 한국항공우주학회지
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• 제37권4호
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• pp.372-382
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• 2009

자체 개발한 SBAS 보정정보 처리 프로그램을 이용하여 MSAS 궤도 보정정보의 정확도를 분석하고, MSAS 전리층 보정정보 대한 적도변이의 영향을 분석하였다. 또한 MSAS 보정정보의 일부분의 제거를 통해 보정정보의 수신지연으로 인한 정확도 저하와 그것이 Protection Level에 미치는 영향을 분석하였다. 그리고 국내에서 MSAS 보정정보를 이용하여 항공기 정밀접근 시 시스템의 무결성 및 가용성에 대해 분석했다.

• 한국지리정보학회지
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• 제7권4호
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• pp.15-23
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• 2004

원격탐사 자료를 효율적으로 사용하기 위해서 위성영상의 기하학적인 왜곡을 제거하는 작업은 반드시 필요하다. 이러한 기하보정을 위해서는 기하보정 된 위성영상, 수치지도, GPS 측량 및 기타 방법에 의해 획득되어진 지상기준점을 필요로 한다. 지금까지의 지상기준점을 이용한 기하보정 방법은 수동적으로 이루어 졌으며, 많은 시간과 노력을 필요로 하였다. 본 논문에서는 GCP Chip 데이터베이스를 이용하여 온라인 상에서 자동으로 기하보정 하는 방법을 제안하였다. 제안된 온라인 자동기하보정 시스템은 영상을 입력하는 부분, 지상기준점 영상을 조정하는 부분, 선택된 지상기준점을 수정 및 갱신하는 부분, 그리고 기하보정 결과를 저장하는 네 가지 부분으로 이루어져 있다. 결론적으로 이러한 온라인 자동 기하보정 시스템을 이용하여 기존의 수동적인 기하보정방법 보다 시간 및 노력을 줄일 수 있으며, 랜셋 영상의 활용에 기여할 것이다.

• 센서학회지
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• 제27권2호
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• pp.86-92
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• 2018

In recent times, motion capture technology using inertial measurement unit (IMU) sensors has been actively used in sports. In this study, we developed a canoe paddle, installed with an IMU and a water level sensor, as a system tool for training and calibration purposes in water sports. The hardware was fabricated to control an attitude heading reference system (AHRS) module, a water level sensor, a communication module, and a wireless charging circuit. We also developed an application program for the mobile device that processes paddling motion data from the paddling operation and also visualizes it. An AHRS module with acceleration, gyro, and geomagnetic sensors each having three axes, and a resistive water level sensor that senses the immersion depth in the water of the paddle represented the paddle motion. The motion data transmitted from the paddle device is internally decoded and classified by the application program in the mobile device to perform visualization and to operate functions of the mobile training/correction system. To conclude, we tried to provide mobile knowledge service through paddle sport data using this technique. The developed system works reasonably well to be used as a basic training and posture correction tool for paddle sports; the transmission delay time of the sensor system is measured within 90 ms, and it shows that there is no complication in its practical usage.

• 대한원격탐사학회지
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• 제38권1호
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• pp.83-101
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• 2022

Accurate atmospheric correction is essential for the analysis of land surface and environmental monitoring. Aerosol optical depth (AOD) information is particularly important in atmospheric correction because the radiation attenuation by Mie scattering makes the differences between the radiation calculated at the satellite sensor and the radiation measured at the land surface. Thus, it is necessary to use high-quality AOD data for an appropriate atmospheric correction of high-resolution satellite images. In this study, we examined the Second Simulation of a Satellite Signal in the Solar Spectrum (6S)-based atmospheric correction results for the Sentinel-2 images in South Korea using raster AOD (MODIS) and single-point AOD (AERONET). The 6S result was overall agreed with the Sentinel-2 level 2 data. Moreover, using raster AOD showed better performance than using single-point AOD. The atmospheric correction using the single-point AOD yielded some inappropriate values for forest and water pixels, where as the atmospheric correction using raster AOD produced stable and natural patterns in accordance with the land cover map. Also, the Sentinel-2 normalized difference vegetation index (NDVI) after the 6S correction had similar patterns to the up scaled drone NDVI, although Sentinel-2 NDVI had relatively low values. Also, the spatial distribution of both images seemed very similar for growing and harvest seasons. Future work will be necessary to make efforts for the gap-filling of AOD data and an accurate bi-directional reflectance distribution function (BRDF) model for high-resolution atmospheric correction. These methods can help improve the land surface monitoring using the future Compact Advanced Satellite 500 in South Korea.

• 한국항공운항학회지
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• 제18권1호
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• pp.11-18
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• 2010

GNSS(Global Navigation Satellite System) Ground Station performs GNSS signal acquisition and processing. This system generates error correction information and distributes them to GNSS users. GNSS Ground Station consists of sensor station which contains receiver and meteorological sensor, monitoring and control subsystem which monitors and controls sensor station, control center which generates error correction information, and uplink station which transmits correction information to navigation satellites. Monitoring and control subsystem acquires and processes navigation data from sensor station. The processed data is transmitted to GNSS control center. Monitoring and control subsystem consists of data acquisition module, data formatting and archiving module, data error correction module, navigation determination module, independent quality monitoring module, and system maintenance and management module. The independent quality monitoring module inspects navigation signal, data, and measurement. This paper introduces independent quality monitoring and performs the analysis using measurement data.

• 한국멀티미디어학회논문지
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• 제20권4호
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• pp.606-613
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• 2017

When the planar area is captured by the depth camera, the shape of the plane in the captured image has perspective projection distortion according to the position of the camera. We can correct the distorted image by the depth information in the plane in the captured area. Previous depth information based perspective distortion correction methods fail to satisfy the real-time property due to a large amount of computation. In this paper, we propose the method of applying the conversion table selectively by measuring the motion of the plane and performing the correction process by parallel processing for correcting perspective projection distortion. By appling the proposed method, the system for correcting perspective projection distortion correct the distorted image, whose resolution is 640x480, as 22.52ms per frame, so the proposed system satisfies the real-time property.