• 인터넷정보학회논문지
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• 제6권5호
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• pp.123-132
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• 2005

초고속 글로벌 이동통신을 제공하기 위해서 3세대망인 UMTS와 WLAN시의 각각의 장단점을 보완하여 통합한다. 현재 B3G 망의 구조는 크게 장기적인 관점의 tightly-coupled방식과 현재 연구의 초점이 되고 있는 loosely-coupled 방식으로 나눌 수 있다. loosely-coupled 방식은 MIP의 HA/FA를 사용하여 수직적 핸드오버를 구현하는 방식이다. Loosely-coupled 방식은 tightly-coupled 방식에 비해 독립적 확장이 가능하고 비교적 구현이 쉬우나 핸드오버의 지연으로 인한 패킷 손실과 서비스 끊김 등의 단점이 있다. 본 논문에서는 이를 개선하기 위하여 HMPv6의 MAP를 사용하여 WLAN과 UMTS의 인터워킹에 대한 수직적 핸드오버 프로시저를 제안한다. 각 단계별 총 지연시간을 통하여 블로킹 확률을 측정해 본 결과 제안된 HMIPv6를 사용한 방식이 기존의 MIP를 사용한 방식보다 성능이 우수함을 확인한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.409-409
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• 2000

In this paper, the implementation of a tightly coupled real-time GPS/INS integrated system is discussed. The hardware is developed for any GPS receiver and any IMU. The navigation software is modularized by tasks, so that can be easily modified when the integrated system is restructured. A van test was performed to show the feasibility of the proposed system.

• 제어로봇시스템학회논문지
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• 제8권12호
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• pp.1067-1075
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• 2002

The system error model for the compensation of the low-cost personal navigation system is derived and the error compensation method using GPS is also proposed. The walking navigation system (WNS) that calculates navigation information through walking detection has small error than INS, but the error also increases with time. In order to improve reliability of the system regardless of time, WNS is integrated with GPS. Since WNS is usually used in urban area, the blockage of CPS signal is frequently occurred. Therefore tightly coupled Kalman filter is used for the integration of WNS and GPS. In this paper, the system model for the design of tightly coupled Kかm filter is designed and measurement is linearized in consideration of moving distance error. It is shown by Monte Carlo simulation that the error is bounded even through the number of visible satellite is less than 4.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.94-94
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• 2000

In this paper, the performance of INS/GPS integration is analyzed. Generally the integration method is classified into two method. One is loosely coupled integration, Another is tightly coupled integration. For the simulation, the error model of Kalman fitter is defined and the result of simulation is analyzed. When the number of visible satellites is less than four, the error of tightly coupled integration is smaller than that of loosely coupled integration. To very the result of simulation, van test that use LP-81 IMU and Millen3151R GPS receiver is carried out.

• 정보통신설비학회논문지
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• 제2권3호
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• pp.48-60
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• 2003

With the rapid successful deployment of WLANs worldwide in numerous hotspots for high data rate, wireless access for data services has created the need to integrate the Cellular Networks with WLAN Networks. The integrated wireless environment will provide the end user a much better service experience along with a single subscription and a single bill. In this paper we focus on inter-working approaches, which combine WLANs and Cellular Networks into an integrated wireless environment capable of ubiquitous access to data services and very high data rates in hotspots areas. We first list the key requirements which are currently being standardized within the 30PP for integration with WLANs networks. We discuss two inter-working architectures namely loosely coupled and tightly coupled This paper will detail the loosely coupled inter-working approach while briefly discussing the tightly coupled inter-working. Finally, we will conclude that the loosely coupled approach is evolutionary and less intrusive than the tightly coupled approach.

• 한국해양공학회지
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• 제33권5호
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• pp.470-478
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• 2019

Because the global positioning system (GPS) is not available in underwater environments, an inertial navigation system (INS)/doppler velocity log (DVL) integrated navigation system is generally implemented. In general, an INS/DVL integrated system adopts a loosely coupled method. However, in this loosely coupled method, although the measurement equation for the filter design is simple, the velocity of the body frame cannot be accurately measured if even one of the DVL transducer signals is not received. In contrast, even if only one or two velocities are measured by the DVL transducers, the tightly coupled method can utilize them as measurements and suppress the error increase of the INS. In this paper, a filter was designed to regenerate the measurements of failed transducers by taking advantage of the tightly coupled method. The regenerated measurements were the normal DVL transducer measurements and the estimated velocity in RPM. In order to effectively estimate the velocity in RPM, a filter was designed considering the effects of the tide. The proposed filter does not switch all of the measurements to RPM if the DVL transducer fails, but only switches information from the failed transducer. In this case, the filter has the advantage of being able to be used as a measurement while continuously estimating the RPM error state. A Monte Carlo simulation was used to determine the performance of the proposed filters, and the scope of the analysis was shown by the standard deviation ($1{\sigma}$, 68%). Finally, the performance of the proposed filter was verified by comparison with the conventional tightly coupled method.

• 제어로봇시스템학회논문지
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• 제13권8호
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• pp.817-823
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• 2007

GPS and INS can be integrated in 3 ways of loose, tight, and ultra-tight configuration. This paper investigates the performance of GPS/INS ultra-tightly integrated system when unscented Kalman filter(UKF) is adopted as well as extended Kalman filter(EKF). Covariance analysis is performed using UFK and EKF for tightly coupled and ultra-tightly coupled systems. Various trajectories such as straight, circle, S-shape, spiral are considered for the simulations of covariance analysis.

• 한국정보전자통신기술학회논문지
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• 제4권3호
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• pp.209-216
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• 2011

최근 시스템 온 칩 내 메모리의 고속 동작을 위해 TCM (Tightly Coupled Memory)를 내장한 설계가 크게 증가하고 있다. 본 논문에서는 시스템 온칩 내 eDRAM을 사용한 TCM 메모리를 위한 새로운 병열 메모리 테스트 구조를 제안한다. 제안하는 기법에서 피테스트 메모리가 테스트 모드에서 병렬 구조로 바뀌고 바운더리 스캔 체인과 함께 내장 메모리의 테스트용이도가 크게 향상된다. 병렬테스트 방식의 메모리는 각 메모리 요소들이 특정한 기능을 수행하도록 구조화되어 있으므로 모듈들로 분할하여 테스트 할 수 있으며 입출력 데이터를 기반으로 동적 테스트 평가 가능하다. 시뮬레이션을 통하여 제안한 기법의 타당성을 검증하였다.

• 한국정보과학회논문지:데이타베이스
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• 제36권4호
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• pp.247-253
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• 2009

지난 십 년간 랭킹은 데이터 마이닝 분야의 활발한 연구분야였다. 그러나 랭킹은 다른 데이터 마이닝 기법들과 비슷하게 RDBMS와는 독립적으로 개발되었고, 그로 인해 기존에 널리 사용되고 있는 RDBMS들과의 연동성이 떨어진다는 단점이 존재하게 되었다. 다른 데이터 마이닝 기법들은 소결합이나 밀결합 접근법을 이용하여 RDBMS와 연동하기 위한 연구가 활발하게 진행되어 왔고, 그 결과 실제로 사용 가능한 응용시스템들이 나오게 되었다. 그러나 랭킹에서는 이와 같은 노력들이 잘 이루어지지 않고 있다. 본 논문에서는 랭킹 작업을 RDBMS에 연동하여 효율적으로 수행하기 위하여 MySQL에 Ranking SVM을 통합하는 작업을 진행하였다. 밀결합 접근법을 기반으로 하는 우리의 구현은 MySQL에 랭킹을 위한 새로운 SQL 명령어를 추가하였고 랭킹 작업의 효율성을 확인하기 위해서 소결합 접근법을 기반으로 하는 Ranking SVM과 성능을 비교 평가하여 훈련단계에서 $10{\sim}40%$, 예측단계에서 평균 60%의 성능향상을 확인할 수 있었다.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.49-54
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• 2011

This paper addresses the performance comparisons of the GPS pseudorange and pseudorange rate measurements in the tightly coupled INS/GPS Navigation systems. Even though the two measurements have the same ability in estimating level attitude errors, pseudorange rate has an advantage in improving estimating heading attitude error performance. The performance of pseudorange and pseudorange rate measurements is compared in numerical simulations and van test.