• Journal of Positioning, Navigation, and Timing
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• 제9권4호
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• pp.337-345
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• 2020

In this paper, an efficient signal tracking method to simultaneously track both GPS L1 C/A and Galileo E1B CBOC(6,1,1/11) using a low cost GPU is proposed. In the existing method that each GNSS signal is processed within 1 ms, more than 2 ms processing time is required in GPU to process 4 ms CBOC signal. It means that real time operation is possible if only Galileo E1B CBOC signal is concerned. But when both GPS C/A and Galileo CBOC is required, it cannot process GPS C/A signal in real time. To process 1 ms GPS C/A and 4 ms Galileo CBOC signal in real time, 4 ms Galileo CBOC signal is divided into 4 by 1 ms signal block in the proposed method. Specially, a buffer that simultaneously manages 1 ms and 4 ms signals is designed. In addition, a module that accumulates the 1 ms correlation value of the Galileo CBOC by 4 ms and passes it to the PLL and DLL is implemented. The operation and performance are evaluated with real measurements in the GPU based SDR. The experimental results show that tracking of more than 16 satellites of GPS C/A and Galileo E1B is possible using the proposed method.

• International Journal of Control, Automation, and Systems
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• 제4권3호
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• pp.333-343
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• 2006

In this paper, the baseline-length information is directly modeled as a measurement for the Wald test, which speeds up the resolution convergence of the integer ambiguity of GPS carrier phase measurements. The convergent speed improvement is demonstrated using numerical simulation and real experiments. It is also shown that the integer ambiguities can be resolved using only four actual satellite measurements with very reasonable convergence speed, if the baseline-length information is used just like one additional observable satellite measurement. Finally, it is shown that the improvement of convergence speed of the Wald test is due to the increase of the probability ratio with the use of the baseline-length constraint.

• 대한교통학회지
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• 제29권4호
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• pp.125-138
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• 2011

도로상의 안개로 인한 시정감소는 교통사고를 유발하는 주된 원인으로 운전자에게 도로의 시정거리를 미리 알려주어 안전운행을 유도하기 위한 안개경고시스템에서는 대부분 안개센서와 같은 고가의 광학센서를 사용하고 있다. 최근 운전자의 시정감각과 유사하면서도 저렴한 카메라를 이용한 시정측정에 관한 연구가 이루어지고 있다. 그러나 기존의 연구는 별도의 표지나 ROI를 기반으로 하고 있으므로 설치가 어렵고 비용이 많이 들며 도로에 기 설치된 CCTV 시스템을 활용하기 어렵다는 문제점을 가지고 있다. 본 논문에서는 도로상에 설치된 카메라 영상을 이용하여 주야간 실시간 시정측정이 가능한 방법을 제안한다. 제안된 방법은 도로모델을 구축하고 카메라 영상으로부터 차량의 이동영역과 가시선을 검출한 후 도로모델에 적용함으로써 매우 쉽고 빠른 시정의 계산이 가능하다. 제안된 방법은 운전자의 시정감각과 유사한 주야간 시정측정이 가능할 뿐만 아니라 시정표지와 같은 부가적인 시설을 사용할 필요가 없고 기존의 CCTV 시스템에 바로 적용할 수 있다는 장점이 있다. 본 논문에서는 중부내륙고속도로에서 획득한 영상을 이용한 실험결과를 통해 본 연구의 현장적용 가능성과 활용방안을 제시하고 신뢰성 검증을 위한 향후 연구방향을 기술한다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권2호
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• pp.155-160
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• 2014

The purpose of this study was to estimate genetic parameters of ultrasound measurements for longissimus dorsi muscle area (LMA), backfat thickness (BFT), and marbling score (MS) in Hanwoo cows (N = 3,062) at the ages between 18 and 42 months. Data were collected from 100 Hanwoo breeding farms in Gyeongbuk province, Korea, in 2007 and 2008. The cows were classified into four different age groups, i.e. 18 to 22 months (the first pregnancy period), 23 to 27 (the first parturition), 28 to 32 (the second pregnancy), and 33 to 42 (the second parturition), respectively. For each age group, a multi-trait animal model was used to estimate variance components and heritabilities of the three traits. The averages of LMA, BFT, and MS measurements across the cows of all age groups were 50.1 $cm^2$, 4.62 mm, and 3.04, respectively and heritability estimates were 0.09, 0.10, and 0.08 for the respective traits. However, when the data were analyzed in different age groups, heritability estimates of LMA and BFT were 0.24 and 0.47, respectively, for the cows of 18 to 22 months of age, and 0.21 for MS in the 28 to 32 months old cows. When the cows of all age groups were used, the estimates of genetic (phenotypic) correlations were 0.43 (0.35), -0.06 (0.34) and 0.21 (0.32) between LMA and BFT, LMA and MS, and BFT and MS, respectively. However, in the cow age group between 28 and 32 (18 and 22) months, the estimates of genetic (phenotypic) correlations were 0.05 (0.29), -0.15 (0.24) and 0.38 (0.24), for the respective pairs of traits. These results suggest that genetic, environmental, and phenotypic variations differ depending on cow age, such that care must be taken when ultrasound measurements are applied to selection of cows for meat quality.

• 한국수자원학회논문집
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• 제45권7호
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• pp.697-711
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• 2012

본 연구에서는 자료동화기법의 하나인 확장 칼만 필터를 이용하여 유량자료의 실시간 품질향상을 수행하였다. 확장 칼만 필터의 상태-공간모형은 강우-유출모형과 관측유량자료를 이용하여 구성하였다. 본 연구에서는 실시간 품질향상 목적을 댐 유입량의 비정상적 고변동성 억제 및 관측유량의 결 오측 보완으로 구분하였으며, 각각의 경우에 적절한 확장 칼만 필터 모형을제시하였다. 이들 모형의 차이는 칼만이득 계산에 필요한 공분산 함수의 추정에 변동성만을 고려하는냐 또는 편의까지를 포함하느냐로 나타난다. 본 연구는 충주댐 유역을 대상으로 적용하였으며, 그 결과 제시된 모형들이 댐 유입량자료나 결 오측이 포함된 유량자료의 실시간 품질향상에 효과적으로 작동함을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.876-879
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• 2002

The paper presents the analysis and results of traffic measurements in the 155 Mbit/s real working ATM backbone network. The traffic is described as an ordered sequence of real-time cells. In this paper we analyze two timescales in which some form of a stochastic process is taking place: cell scale and burst scale. We present another way to describe the cell flow in ATM networks by definition the function, designed to be the probability of the burst of length ∫in n sequential slots.

• International journal of advanced smart convergence
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• 제7권1호
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• pp.24-32
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• 2018

An outlier detection method using mixed prediction model has been described in this paper. The mixed prediction model consists of time-series model and regression model. The parameter estimation of the prediction model was performed using supervised learning and a genetic algorithm is adopted for a learning method. The experiments were performed in artificial and real data set. The prediction performance is compared with the existing prediction methods using artificial data. Outlier detection is conducted using the real sensor measurements in a dam. The validity of the proposed method was shown in the experiments.

• 한국멀티미디어학회논문지
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• 제17권2호
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• pp.152-159
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• 2014

최근 클라우드 컴퓨팅 기술의 발전에 따라 해저지도 데이터의 효율적인 측정, 기록 및 업데이트하는 분야에서의 원격탐사 기술과 클라우드 컴퓨팅 기술의 활용이 확대되고 있다. 실제 해양 분야에서 수심측정 및 측정 데이터 관리, 유통, 디스플레이 장비 개발 및 보급에 많은 시간과 비용이 발생하고 있다. 이러한 시스템을 개선하고자 실시간 3차원 디스플레이 시스템을 통하여 해당 위치에서의 측정 활동의 중요도를 판단할 수 있으며, 측정 활동의 시간과 비용 감소로 이어질 수 있다. 해양조사선 및 원격탐사 장비 등 다양한 경로를 통해 측정된 데이터는 클라우드 컴퓨팅 기술을 활용하여 처리, 관리된다. 본 논문에서는 원격탐사를 통한 수심측정과 동시에 실시간 3차원으로 디스플레이하는 시스템을 제안한다. 제안된 실시간 3차원 디스플레이 시스템은 해저지형뿐만 아니라 육지의 지형 측량 분야에서도 효과적으로 적용될 수 있다.

• Ocean Science Journal
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• 제40권1호
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• pp.25-44
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• 2005

Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-tenn current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.626-635
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• 2012

Most of single frequency GPS receivers utilize low-quality crystal oscillators. If a lowquality crystal oscillator is utilized as the time reference of a GPS receiver, the receiver's clock bias grows very fast due to its inherent low precision and poor stability. To prevent the clock bias becoming too large, large clock jumps are intentionally injected to the clock bias and the time offset for clock steering purpose. The abrupt changes in the clock bias and the time offset, if not properly considered, induce serious accuracy degradation in relative differential positioning. To prevent the accuracy degradation, this paper proposes an efficient and systematic method to eliminate the undesirable clock jump effects. Experiment results based on real measurements verify the effectiveness of the propose method.