• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1152-1154
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• 2003

The needs of 3-D data have been increasing for various applications like visualization, 3-D modeling, planning and management as well as entertainment. Mobile mapping has become a quick and practical means for acquiring necessary 3-D data for above-mentioned applications. A mobile mapping system mainly consists of two main components, viz. data acquisition devices and positioning devices. The data acquisition devices consist of CCD cameras or/and laser scanners. The positioning devices consist of GPS, INS, Odometer (shaft encoder) and some other referencing devices. The overall accuracy of mobile mapping system depends on the accuracy of positioning devices and their integrated output. Though, GPS is the main input device for the position information, the signal is not available for the computation of position all the times in urban area. The GPS satellites are normally obstructed by high-rise buildings. Thus it is very important to understand the accuracy of such a system in different environments and means to solve such problems. We have developed a mobile mapping system called VLMS (Vehicle-borne Laser Mapping System), which consists of CCD Cameras, Laser scanners, GPS, INS and Odometer. In this paper, we will present and discuss the accuracy of this system with data acquired in different environments (open area, urban area, tunnel, express way etc) by analyzing the data with respect to other existing digital data.

• Spatial Information Research
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• 제19권3호
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• pp.33-42
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• 2011

항공사진을 이용한 3차원공간정보구축 방법이 대두됨에 따라, 효율적인 작업 방법과 활용 방안에 대한 논의가 지속되어져 오고 있다. Pictometry를 활용한 3차원공간정보구축에는 경사사진과 수직사진이 동시에 획득되어지므로 기존 사진측량이론과 상이한 다각촬영(Multi-Looking)카메라의 작업방법에 따라 3차원 위치결정을 수행한다. 이때 지상기준점의 관측수량 및 배치는 최종성과물인 정밀정사영상(True Orthoimage)의 절대정확도에 영향을 미치게 된다. 따라서 본 연구에서는 지상기준점 수량 및 배치에 따른 정밀정사영상의 정확도 평가를 수행하고 허용오차범위를 만족시키는 지상기준점 선점 기준을 확인하였으며 다각촬영카메라의 3차원위치결정 작업방법에서 효율적인 지상기준점 관측 방안을 제시하였다.

• Journal of Positioning, Navigation, and Timing
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• 제7권3호
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• pp.155-163
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• 2018

This study examined methods to enhance navigation performance and reduce the divergence of navigation solutions that may occur in the event of global positioning system (GPS) failure by integrating the GPS/inertial navigation system (INS) with the three-dimensional (3D) magnetic vector measurements of a magnetometer. A magnetic heading aiding method that employs a magnetometer has been widely used to enhance the heading performance in low-cost GPS/INS navigation systems with insufficient observability. However, in the case of GPS failure, wrong heading information may further accelerate the divergence of the navigation solution. In this study, a method of integrating the 3D magnetic vector measurements of a magnetometer is proposed as a countermeasure for the case where the GPS fails. As the proposed method does not require attitude information for integration unlike the existing magnetic heading aiding method, it is applicable even in case of GPS failure. In addition, the existing magnetic heading aiding method utilizes only one-dimensional information in the heading direction, whereas the proposed method uses the two-dimensional attitude information of the magnetic vector, thus improving the observability of the system. To confirm the effect of the proposed method, simulation was performed for the normal operation and failure situation of GPS. The result confirmed that the proposed method improved the accuracy of the navigation solution and reduced the divergence speed of the navigation solution in the case of GPS failure, as compared with that of the existing method.

• 한국인터넷방송통신학회논문지
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• 제15권1호
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• pp.199-205
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• 2015

많은 사용자가 항상 휴대하는 스마트폰을 대상으로 실내에서의 위치 인식을 위한 기술 개발이 매우 활발하다. 특히 음향 신호를 이용한 TDOA 방식의 위치 측정 시스템도 많이 연구되고 있는데, 이 방식은 스마트폰의 스피커와 음향 신호를 수신하기 위한 위치 측정 장치에 설치된 마이크들 사이의 거리를 측정하고 관련 쌍곡선 수식을 계산하여 스마트폰의 위치를 추정하는 것이다. 그러나 스피커와 각 마이크 사이의 거리를 측정하는 것에 항상 오차가 있고, 게다가 위치 측정 장치에 설치된 음향 센서인 마이크의 설치 위치 오차에 따라서 위치 측정 오차가 매우 크게 발생한다. 본 논문에서는 3차원 TDOA 위치 측정 시스템에서 음향 센서의 위치 오차에 따른 위치 측정 오차가 PDOP 시뮬레이션과 실험으로 분석되었다.

• 대한인간공학회지
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• 제19권3호
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• pp.39-49
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• 2000

During human-computer interaction(HCI), people typically send inputs to computers through electromechanical pointing devices. Many applied studies have therefore evaluated cursor-positioning movements made with various pointing devices. Though there were so many studies about performance of various pointing devices, it was nearly impossible to compare device performance each other until the Fitts' law was applied. It does appear that Fitts' law may predict performance reasonably well for the one C-D gain level. But in varying C-D gain levels, Fitts' law could not predict movement time. This study investigated the effects of C-D gain in mouse movement time and suggested a revised Fitts' model including C-D gain as an independent variable. The revised Fitts' model may use to measure the performance of various devices in varying C-D gain levels.

• Journal of Positioning, Navigation, and Timing
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• 제10권3호
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• pp.221-228
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• 2021

The Korea Augmentation Satellite System (KASS) is a Korean Satellite Based Augmentation System (SBAS) that has been under development since 2014 with the goal of providing Approach Procedure with Vertical guidance (APV)-I Safety of Life (SoL) services. KASS Control Station (KCS) is a subsystem that controls and monitors KASS systems. It also serves to store data generated by KASS. KCS has now completed detailed design and implementation and verification is in progress. This paper presents verification procedures and verification items for KCS verification activities and presents management measures for defects occurring during the verification phase.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.438-445
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• 2000

Positioning garlic cloves in upright standing in garlic field has been regarded as a very important job because it affects clove rooting, growing and, eventually, quality and yield in garlic production, Because of the geometrical uniqueness and irregularity of garlic cloves in shape, the planting operation has been conducted by manual work that needs a tremendous human labors and increases garlic production cost. The overall objective of this research was to develop garlic planting machine through investigating physical properties of garlic and designing clove upright positioning device after figuring out the factors affecting metering device and upright clove positioning mechanism. With the outcomes of the metering and posture positioning experiment, a garlic clove planter having twelve planting rows was developed for 37kW type tractor and feasibility test was carried out in the field. And, According to the performance test and cost analysis, the planter could accomplish planting operation of one hectare plot in 6.3 hours giving 48 times better efficiency, 6.3hrs/ha, and 74.2% of production cost reduction effect, 1,092,546won/ha, than the manual works of 299hrs/ha and 282,258won/ha. And, break-even point ofthe planter was calculated as of 2.71 hectares.

• 전자통신동향분석
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• 제38권3호
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• pp.11-19
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• 2023

Drones, which were early operated by remote control, have evolved to enable autonomous flight by combining various sensors and software tools. In particular, autonomous flight of drones was possible since the application of GNSS-RTK (global navigation satellite system with real-time kinematic positioning), a precision satellite navigation technology. For instance, unmanned drone delivery based on GNSS-RTK data was demonstrated for pizza delivery in Korea for the first time in 2021. However, the vulnerabilities of GNSS-RTK should be overcome for delivery drones to be commercialized. In particular, jamming in the navigation system and low positioning accuracy in urban areas should be addressed. Solving these two problems can lead to stable flight, takeoff, and landing of drones in urban areas, and the corresponding solutions are expected to establish a hybrid positioning technology. We discuss current trends in hybrid positioning technology that can either replace or complement GNSS-RTK for stable drone autonomous flight.

• 한국전자통신학회논문지
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• 제11권2호
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• pp.145-150
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• 2016

자율주행 차량 구현에 있어 차량의 위치에 대한 정확한 정보가 실시간으로 제공되어야 한다. 이동기준국 차분 측위 기술은 차량에 복수의 안테나에서 수신한 신호의 위상차를 통해 정밀 측위 정보를 생성하는 기술로, 이를 위해 차량의 평평하고 넓은 루프를 접지면으로 하는 이중대역 및 이중 원형편파 안테나 개발이 필수적이다. 본 논문에서 제안하는 안테나는 GPS L1과 L2 주파수 대역에서 공진을 일으키는 이중대역 안테나로써, 기존 안테나와 달리 급전부가 안테나 측면에 위치하여 복수의 안테나를 필요로 하는 시스템에 적합하다. 안테나 설계안은 중요 파라미터들의 이론값을 토대로 모델링한 초기 모델을 3D 전파시뮬레이션 소프트웨어를 이용해 최적화하는 방법으로 도출하였다. 최적화된 안테나의 시뮬레이션값과 측정값을 분석한 결과, L1과 L2에서 대역폭 6.1%와 3.7%, 축비 1% 이상임을 확인하였다. 안테나 크기는 $73mm{\times}73mm{\times}6.4mm$로 소형 구조의 장점을 갖췄다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.751-756
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• 2002

Since the operation of the first satellite-based navigation services, satellite positioning has played an increasing role in both surveying and navigation, and has become an indispensable tool for precise relative positioning. However, in some situations, e.g. at a low angle of elevation, the use of satellites for navigation is seriously restricted because obstacles like buildings and mountains can block signals. As a mean to resolve this problem, the quasi-zenith satellite system has been proposed as a next-generation satellite navigation system. Quasi-zenith satellite is a system which simultaneously deploys several satellites in a quasi-zenith geostationary orbit so that one of the satellites always stay close to the zenith if viewed from a specific point on the ground of East Asia. Thus, if a position measurement function compatible with GPS is installed in the quasi-zenith and stationary satellites, and these satellites are utilized together with the GPS, four satellites can be accessed simultaneously nearly all day long and a substantial improvement in position measurement, especially in metropolitan areas, can be achieved. The purpose of this paper is to evaluate the effectiveness of quasi-zenith satellite system on positioning accuracy improvement through simulation by using precise orbital information of the satellites and a three-Dimensional digital map. Through this simulation system, it is possible to calculate the number of simultaneously visible satellites and available area of the positioning without the need of actual observation.