• The Journal of Korea Robotics Society
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• v.7 no.1
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• pp.29-34
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• 2012

This paper suggests a new observation model for Extended Kalman Filter based Simultaneous Localization and Mapping (EKF-SLAM). Since the EKF framework linearizes non-linear functions around the current estimate, the conventional line model has large linearization errors when a mobile robot locates faraway from its initial position. On the other hand, the model that we propose yields less linearization error with respect to the landmark position and thus suitable in a large-scale environment. To achieve it, we build up a three-dimensional space by adding a virtual axis to the robot's two-dimensional coordinate system and extract a plane by using a detected line on the two-dimensional space and the virtual axis. Since Jacobian matrix with respect to the landmark position has small value, we can estimate the position of landmarks better than the conventional line model. The simulation results verify that the new model yields less linearization errors than the conventional line model.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.273-282
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• 2005

A star sensor daytime observation model is developed in order to test the performance of the star sensor useful for daylight application. The centroid errors of the star sensor in the day time application are computed by using the model. The standard atmospheric model (LOWTRAN7) is utilized to calculate the physical quantities of the daylight atmospheric environments where the star sensor is immersed. This observation model takes the separation angles between the sun and star, the centroid algorithm and the various system specifications of the star sensor into the account. The developed star sensor model will provide more realistic measurement errors in estimating the performance of the attitude determination from the vector observations.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.16-24
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• 2010

This paper is proposed a novel fuzzy disturbance observer based on backstepping method for nonlinear systems with unknown disturbance. Using fuzzy logic systems, a fuzzy disturbance observer with the disturbance observation input is introduced for unknown disturbance. To guarantee that the proposed disturbance observer estimates the unknown disturbance, the disturbance observation error dynamic system is employed. Under the framework of the backstepping design, the fuzzy disturbance observer is constructed recursively and an adaptive laws and the disturbance observation input are derived. Numerical examples are given to demonstrate the validity of our proposed disturbance observer for nonlinear systems.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.173-180
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• 1994

Milk progesterone concentrations were measured in 111 dairy cows for confirming the estrus observation and for the early pregnancy diagnosis. Of the 56 cows inseminated, 52 cows(92.8%) were an ovulatory estrus, 2 cows(3.6%) were an unovulatory estrus, and 2 cows(3.6%) were the error of estrus observation, respectively. Milk progesterone concentrations at 21 and 24 days after artificial insemination were significantly higher in 23 pregnant cows compared with those in 5 non-pregnant cows(P<0.05). The accuracy rate for early pregnancy diagnosis in 27 cows achieved when the discriminatory concentration at 21 days after artificial insemination was placed at 2.0 ng/ml skim milk, was 91.3% for positive diagnosis and 100% for negative diagnosis, respectively. These results indicated that milk progesterone determination at 0, 6 and 21 days after artificial insemination can be utilized for confirming the estrus observation and for early pregnancy diagnosis. In conclusion, milk progesterone determination is useful diagnostic tool for monitoring the reproductive performance.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.155-159
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• 1999

The mini-weather buoy using newly developed Weather Observation Through Ambient Noise (WOTAN) technology is developed. The buoy uses the cellular phone system for communication between the mini-weather buoy and the receiving station. The developed mini-weather buoy was deployed near Kijang and the comparison with land observation station was good: the rms error for wind speed estimation from underwater ambient noise was about 1 m/s. The only shortcoming of developed mini-weather buoy is that the buoy must be within the range of the cellular phone system, but it can be easily solved when satellite phone system is available.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.585-594
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• 2014

This study Analyzed four of seven runoffs which had happened in 2012 in comparison with the runoffs shown in Kalesto data, using the fixed surface image velocimetry (FSIV) installed at Oedo stream, Jeju Island. As a result of identifying a runoff curve graph, it was analyzed that the flood runoffs calculated with two observation devices were almost equivalent. As the differences in peak flows were 10 $m^3/s$, 0.7 $m^3/s$ and 3 $m^3/s$, the very similar result values were calculated. Even though there were errors in RMSE(Root Mean Square Error) made by two observation devices according to the degree of the peak flow, the values of $R^2$ by flood event were 0.89, 0.87, 0.86 and 0.82, showing the result values almost close to 1. Therefore, there was a very high correlation in flood runoffs calculated with two observation devices. This research method was considered to be a very suitable method to measure unexpected flood runoffs which could happen in the island area such as Jeju island during bad weather.

• Journal of Forest and Environmental Science
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• v.37 no.4
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• pp.331-337
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• 2021

This study is designed according to the fact that the feces presumed to be from a Prionailurus bengalensis was found in Ulleungdo Island, where Prionailurus bengalensis is not known to inhabit, and that visual observation of the feces may cause errors in species identification. The feces observed in Ulleungdo Island on October 21, 2019 and August 29, 2020, in Gyeongju on December 4, 2020, and in Jecheon on December 7, 2020 was found intactly on grass, not buried in the ground. Although it was difficult to distinguish and identify the feces of Felis catus and Prionailurus bengalensis with visual observation, the feces collected from Ulleungdo Island was closely related to the Felis catus according to the genetic analysis whereas the ones collected from Gyeongju and Jecheon was identified from Prionailurus bengalensis. Therefore through the gene analysis, this study proved that visual observation of feces with similar appearance, specifically the feces found in Ulleungdo Island, Gyeongju, and Jecheon, may cause errors in species identification. It is judged to be necessary to analyze fields signs and genes for the species identification when using the feces of Felis catus and Prionailurus bengalensis.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.867-872
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• 2022

The effect of load is an important factor in precise speed control of a motor. n this study, we design a state observer that can estimate and define one state of disturbance including errors and nonlinear terms of mathematical models, which is not easy with a mathematical model. Then, the observation gain is set so that the estimation error of the state observation converges to 0, and the estimated state is used in the back stepping controller to design a controller capable of precise speed tracking. As a result of applying to 1 [hw] class Interior Permanent Magnet Synchronous Motor, excellent stste variable observation and tracking performance can be confirmed.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1200-1207
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• 2017

Sensors in a smartphone can be used to measure various physical quantities. In this paper, we propose an object localization scheme in a three dimenstional using a smart phone. The proposed scheme estimates the location of an object by observing it from several different points. The direction to the target object and the locations of the observation points are collected at each observation point using the location sensor and the orientation sensor in the smartphone. Based on these observations, the proposed scheme derives three dimensional line of sight vectors and estimates the location of the target object that minimizes the estimation error. We implemented the proposed scheme on an Android smartphone and tested its performance by estimating the height of a building and characteristics of the proposed approach.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.499-499
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• 2002

The goal of this study is to apply and evaluate the precipitation outflow in river basin using satellite data and GIS for proposing the efficient watershed management method. Not only precipitation outflow data but also various spatial data such as digital map, soil map, geologic map and multi-temporal TM images were used. Using landcover classification result and soil map were applied to estimate the average CN. The CN value of 63.37 by SCS method was produced in AMC-2 condition otherwise the result of direct estimation with observation method was 63 CN value. The relative error of two results was 0.59%. It can be possible to apply the satellite data for precipitation outflow analysis. For more accurate and credible analysis of this, the more multi-temporal satellite and real observation data will be needed.