• 한국군사과학기술학회지
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• 제15권5호
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• pp.557-564
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• 2012

This paper presents UGV localization using multi-sensor fusion based on federated filter in outdoor environments. The conventional GPS/INS integrated system does not guarantee the robustness of localization because GPS is vulnerable to external disturbances. In many environments, however, vision system is very efficient because there are many features compared to the open space and these features can provide much information for UGV localization. Thus, this paper uses the scene matching and pose estimation based vision navigation, magnetic compass and odometer to cope with the GPS-denied environments. NR-mode federated filter is used for system safety. The experiment results with a predefined path demonstrate enhancement of the robustness and accuracy of localization in outdoor environments.

• 한국컴퓨터그래픽스학회논문지
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• 제3권2호
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• pp.15-25
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• 1997

본 논문은 대규모 가상 세계의 제작 과정과 내비게이션에 관한 접근 방법을 기술하고, 그 과정에서 발견한 문제점과 개선 방향, 그리고 관련된 연구 이슈에 대해서 논한다. 대상 가상 세계로서 KAIST캠퍼스를 택하여 캠퍼스의 지형, 건물 및 구조물들을 모델링하고 배치하여 통합된 가상 세계를 구축하였다. 대규모 가상 세계를 제작하는 것은 그 자체가 중요한 연구 이슈가 될 뿐만 아니라 제작된 가상 세계는 캠퍼스 안내 시스템, 원격 교육, 디지털 라이브러리, 인터넷 응용 등에 사용될 수 있으며 실시간 컴퓨터 그래픽스를 연구하기 위한 testbed로 사용될 수 있다.

• 한국정보통신학회논문지
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• 제15권5호
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• pp.1111-1118
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• 2011

선박에 장착된 장비들을 통하여 수집된 다양한 데이터는 선박의 안전한 운항을 위하여 사용된다. 하지만 이러한 다양성으로 인해 데이터를 각각 관리하기에는 어려움이 있으므로 이를 통합 관리하기 위하여 데이터베이스를 구축하는 것이 효율적이다. 그러나 선박에서의 데이터베이스는 통상의 데이터베이스에 비해 급격한 저장 빈도 때문에 용량 초과 문제가 자주 발생한다. 본 논문에서는 이를 해결하고자 데이터의 샘플링과 삭제를 통하여 데이터베이스의 용량을 확보하면서 통합 관리가 가능한 다단 데이터베이스를 설계하고 구현한 후, 그 효율성을 시험한다.

• 한국항만학회지
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• 제12권2호
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• pp.269-280
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• 1998

A Wave-induced current model is developed in our study and this model is composed with wave transform model and current model. Two types of wave model are used in our study one is Copeland(1985) type which is applied in the offshore region and the other is Watanabe and Maruyama(1984) type which is applied in the surf zone. The depth-integrated and time-averaged governing equation of an unsteady nonlinear form is used in the wave induced current model. Lateral mixing radiation stresses surface and bottom stresses are considered in our current model. Copeland’s(1976) is used as a surface friction formula. Numerical solutions are obtained by Leendertse scheme and compared with Noda’s(1974) experimental results for the uniform slope coastal region test and Nishimura & Naruyama’s (1985) experimental results and numerical simulation results for the detached breakwater. The results from our wave model and wave model and wave-induced current model show good agreements with the others and also show nonlinear effects around the detached breakwater. The model in this study can be applied in the surf zone considering the friction stresses.

• 한국항공우주학회지
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• 제45권5호
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• pp.401-408
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• 2017

본 논문에서는 저가 하드웨어 기반의 멀티로터용 비행제어 컴퓨터의 하드웨어 개발과 항법 및 제어 알고리즘의 설계 및 구현, 그리고 실제 비행실험을 통한 검증 과정을 서술하였다. 개발된 비행제어 컴퓨터는 마이크로컨트롤러를 통하여 멀티로터를 안정적으로 제어하며 통합된 Linux 컴퓨터를 활용하여 복잡한 임무에 대응이 가능하도록 설계되었다. 항법 해는 Complementary Filter를 통하여 500 Hz의 속도로 계산을 수행하고, 멀티로터의 운동모델을 기반으로 Observer를 설계, 측정 잡음을 크게 줄였다. 제어 알고리즘은 3차원 Curve Fitting을 통하여 얻은 Feed-forward Term을 사용하여 반응속도를 크게 향상시켰으며, 다수의 비행실험을 통하여 실제 상황에서 효과적으로 동작함을 확인하였다.

• 전기전자학회논문지
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• 제23권1호
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• pp.44-52
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• 2019

본 논문은 라이다 센싱 정보와 RGB-D 카메라 영상 정보를 융합하여 이용하는 교육용 실내 자율주행 로봇 시스템을 구현한다. 이 시스템은 라이다 센싱 정보를 획득하기 위해 기존의 소 채널 라이다 센싱 방식을 이용한다. 또한 소 채널 라이다 센싱 방식의 약점을 보완하기 위해, RGB-D 카메라 깊이 영상과 딥러닝 기반 객체인식 알고리즘을 이용하는 3차원 구조물 인식 방법을 제안하고 이 시스템에 적용한다.

• 한국해양공학회지
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• 제34권6호
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• pp.475-480
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• 2020

Underwater operating platforms face difficulties regarding power supply and communications. To overcome these difficulties, this study proposes a hybrid surface and underwater vehicle (HSUV) and presents the development of the platform, control algorithms, and results of field tests. The HSUV is capable of supplying reliable power to the unmanned underwater vehicle (UUV) and obtaining data in real time by using a tether cable between the UUV and the unmanned surface vehicle (USV). The HSUV uses global positioning system (GPS) and ultra-short base line sensors to determine the relative location of the UUV. Way point (WP) and dynamic positioning (DP) algorithms were developed to enable the HSUV to perform unmanned exploration. After reaching the target point using the WP algorithm, the DP algorithm enables USV to maintain position while withstanding environmental disturbances. To ensure the navigation performance at sea, performance tests of GPS, attitude/heading reference system, and side scan sonar were conducted. Based on these results, manual operation, WP, and DP tests were conducted at sea. WP and DP test results and side scan sonar images during the sea trials are presented.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.63-69
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• 2022

We develop a smart tourism information system that provides smart tourism services to free independent tourists (FITs) through various content distribution channels such as mobile apps, Instagram, YouTube, and chatbots. The smart tourism information system provides location and storytelling-based tourism information, accommodation, restaurant information, and recommended travel products so that tourists can create a travel itinerary based on personalized situation awareness. The smart tourism information system also provides smart tourism services using commercial maps, navigation, and weather forecast APIs from the Korea Meteorological Administration to provide smart tour guide services to tourists who travel according to the travel itinerary. In this paper, we develop the React Native app that provides smart tourism services provided by the smart tourism information system. The smart tourism React Native app has implemented two methods: a method that directly connects to the smart tourism information system, and a method that provides services by interworking through the GraphQL Query Language developed by META (Facebook). The smart tourism React Native app implements OSMU (One Source Multi-use) by providing tourism information from mobile apps, photos from Instagram, and drone videos from YouTube as an integrated UI.

• 한국정밀공학회지
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• 제13권8호
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• pp.112-119
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• 1996

Among the various type of accelerometer, the servo rebalancing type accelermoter can be suitable for Inertial Navigation System, because of its high sensitivity and good response in low frequency. In this paper, we proposed a new technology to control inductive tuype accelerometer utilizing digital PWM method. The new developed digital PWM control has special design scheme for transmitting measurement value to outer device in its servo ollp. So it has no quantized error of transforming outputs of sensors to digital domain. The quantized error may make serious problem in INS system, because outputs of sensor are integrated once or twice by digital computer and it happens every sensor reading times. Therefore, in order to get the accurate information such as displacement, it is necessary to measure accurately the input current. In addition, Digital Signal Processing needs digital data transmission, digital PWM method is adaptive for this purpose. We realized a practical circuit for digital PWM control, analyzed the stability of the circuit, and designed the controller etc. In this study, we solved many practical problem for this application, and got out good results.

• 대기
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• 제33권1호
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• pp.33-47
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• 2023

In this study, for the application of observation errors to the Korean Integrated Model (KIM) to utilize the Constellation Observing System for Meteorology, Ionosphere & Climate-2 (COSMIC-2) new satellites, the observation errors were diagnosed based on the Desroziers method using the cost function in the process of variational data assimilation. We calculated observation errors for all observational species being utilized for KIM and compared with their relative values. The observation error of the calculated the Global Navigation Satellite System Radio Occultation (GNSS RO) was about six times smaller than that of other satellites. In order to balance with other satellites, we conducted two experiments in which the GNSS RO data expanded by about twice the observation error. The performance of the analysis field was significantly improved in the tropics, where the COSMIC-2 data are more available, and in the Southern Hemisphere, where the influence of GNSS RO data is significantly greater. In particular, the prediction performance of the Southern Hemisphere was improved by doubling the observation error in global region, rather than doubling the COSMIC-2 data only in areas with high density, which seems to have been balanced with other observations.