• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.331-337
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• 2002

In this paper we propose extended Kalman filter (EKF)-trilateration method which associates EKF to conventional radiolocation technique, trilateration in order to improve the accuracy of dynamic orbit determination of geostationary satellite for broadcasting of highly accurate Standard Time/Frequency Signal (STFS). We then compare to analyze the time accuracies of three techniques which are differential mode, trilateration locating one of four calibrated earth stations on a neighboring country, and domestic-only baseline EKF-trilateration. Computer simulations have shown that in spite of domestic-only baseline EKF-trilateration of poor GDOP, it is possible to track and locate satellite with an accuracy of a few hundred meter which is the performance 10 times more accurate than trilateration can provide. Finally we can provide standard time service with the time accuracy better than a few ns (frequency stability : 10$\^$-14/ over 7 days) all around Korea peninsula.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.1
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• pp.1-13
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• 2024

This study assessed the efficacy of improving the accuracy of reservoir water level prediction models by employing automated machine learning models and efficient cross-validation methods for time-series data. Considering the inherent complexity and non-linearity of time-series data related to reservoir water levels, we proposed an optimized approach for model selection and training. The performance of twelve models was evaluated for the Obong Reservoir in Gangneung, Gangwon Province, using the TPOT (Tree-based Pipeline Optimization Tool) and four cross-validation methods, which led to the determination of the optimal pipeline model. The pipeline model consisting of Extra Tree, Stacking Ridge Regression, and Simple Ridge Regression showed outstanding predictive performance for both training and test data, with an R² (Coefficient of determination) and NSE (Nash-Sutcliffe Efficiency) exceeding 0.93. On the other hand, for predictions of water levels 12 hours later, the pipeline model selected through time-series split cross-validation accurately captured the change pattern of time-series water level data during the test period, with an NSE exceeding 0.99. The methodology proposed in this study is expected to greatly contribute to the efficient generation of reservoir water level predictions in regions with high rainfall variability.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.333-344
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• 2011

An optical tracking system has advantages for observing geostationary earth orbit (GEO) satellites relatively over other types of observation system. Regular surveying for unidentified space objects with the optical tracking system can be an early warning tool for the safety of five Korean active GEO satellites. Two strategies of positioning on the observed image of Communication, Ocean and Meteorological Satellite 1 are tested and compared. Photometric method has a half root mean square error against streak method. Also eccentricity method for initial orbit determination (IOD) is tested with simulation data and real observation data. Under 10 minutes observation time interval, eccentricity method shows relatively better IOD results than the other time interval. For follow-up observation of unidentified space objects, at least two consecutive observations are needed in 5 minutes to determine orbit for geosynchronous orbit space objects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5587-5594
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• 2012

Determination of the soil-water characteristic curve is one of the most important things to solve geotechnical engineering problems. Expecially, convenient and reliable method to measure the soil-water characteristic curve during drying and wetting cycles is required with lower labor input, more independence from operator experience, and shorter testing time than other available methods. Many measurement methods including the flow pump system have been developed to characterize the soil-water characteristic curve for the several decades. This study measured the soil-water characteristic curve during drying and wetting cycles using a suction control technique with the flow pump system. Two test materials were used for determination of the soil-water characteristic curve, and it is concluded that suction control technique is suitable for determination of the soil-water characteristic curve and characterization of the hydraulic hysteresis with varying test conditions. Especially, the suction control technique can reduce error of measurement and save time in measuring the soil-water characteristic curve due to automated system and high degree of precision.

• Journal of environmental and Sanitary engineering
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• v.5 no.2
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• pp.63-80
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• 1990

A sensitive and simple analytical system for the simultaneous determination of residual oxytetracycline, tetracycline, and doxycycline in honey was described, and that the analytical method for determination of residual propionic acid in honey was established. Experimental subjects were purchased four kinds of honey, native kind honey, acaccia honey, mixed floral honey, chestnut honey in Kyung Sang Nam Do. Several microbiological methods are available to determine tetracycline antibiotecs(TCs) in foods but their precision apears to be variable and the specificity is questionable. These methods are considered to be not suitable for analysis of tetracycline antibiotics in honey because honey itself has bacteriostatic action. For determination of tetracycline antibiotics in honey, therefore the High Performance Liquid Chromatography(HPLC) method was applied, and the propionic acid were determined by Gas Chromatography(5.C). Ethylacetate, as an extract solvent, was found to be suitable for seperation of TCs in honey, but methanol and acetone were not. The recoverly rate of Oxytetracycline(OTC), Tetracycline(TC), Doxycycline(DC) from honey spiked at a level of 10 $\mu $g/g were 97%, 89%, and 91%, respectively. The cailbration curve in TCs was linear expression from 2$\mu $g/ml to 10$\mu $g/ml. As the results of analysis, the residual tetracycline antibiotics were not detected in the 100 samples of honey. The recovery rate of propionic acid from honey spiked at level of 10$\mu $g/g was 98.3% , and the calibra lion curves were linear expression from 21$\mu $g/ml to 101$\mu $g/ml. As the results of analysis, the residual propionic acid was not detected in the 100 samples of honey. Retention time(min) of OTC, DC, and TC were 3.35, 4.61, and 5.30 minutes at the conditions of table 2, respectively, and retention time(min) of propionic acid was 3.50 minutes at the conditions of table 3. The residual TCs and propionic acid were not detected in the 100 samples of honey, but there is a possibility that antibiotics or propionic acid will be to remain in honey if they are used during product period in order to prevent putrefaction of honey-bee.

• Analytical Science and Technology
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• v.26 no.4
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• pp.256-261
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• 2013

The efficiency of the two extractions (refluxing extraction and heating-block extraction) was compared to develop the simple analytical method for the determination of capsaicinoids, including capsaicin and dihydrocapsaicin in red pepper powder. For the method development, the parameters, including particle size, extraction time and sample size, were evaluated using ultra high performance liquid chromatography (u-HPLC). It was found that the most effective extraction time of the refluxing extraction was 3 hr. The higher extraction efficiency was obtained with the fine particle of a mild red pepper powder, while the particle size did not affect the extraction efficiency in case of the hot red pepper powder. The higher extraction efficiency was obtained with the small size of sample taken because of the ratio of the large extracting solvent to sample amount. The extraction efficiency of the refluxing method was 3-9% higher than that of the heating-block method, however, the heating-block method could be applied to the determination of capsaicinoids in the red pepper powder for the purpose of quality control of the product.

• Korean Journal of Veterinary Service
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• v.39 no.1
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• pp.7-12
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• 2016

The Autofom is a equipment for predicting the amount of pig carcasses meat using the 16 ultrasonic sensors to measure in real time and it was established in Dodram LPC in Gyeonggi Province of Korea for the first time. This study was carried out to validate the reliability of Autofom statistically and to establish guideline for developing a analytic formula through comparing the measurement between Autofom and dissection. The ham parts of sixty-six pig carcasses were measured with Autofom and by two experimental performers. The weight means and standard deviations of ham parts including bone by measurements with Autofom and dissection were $10.69{\pm}0.81kg$ and $10.77{\pm}0.94kg$, respectively a strong positive correlation (P<0.01) was identified, with a coefficient of determination ($R^2$) of 0.82. The weight means and standard deviations of lean ham parts by measurements with Autofom and dissection were $7.41{\pm}0.58kg$ and $7.42{\pm}0.89kg$, respectively a strong positive correlation (P<0.01) was identified, with a coefficient of determination ($R^2$) of 0.72. The root mean square errors of two groups were 0.40 and 0.50, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.3
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• pp.67-73
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• 1991

To define a small river in Korea. hydrologic- and geographic-characteristics. such as watershed area, channel slope, channel length and time of concentration are investigated and their limits are presented. The current equations of design-width-determination of the small rivers are examined and two equations for the design-width-determination of the small rivers have been suggested in this paper. A small river in Korea can be defined that watershed area is less than $10km^2$, channel length less than 6 km, channel slope over 0.02. time of concentration less than 30 minutes. As Band Q are defined as a design width and a design flood, respectively, the suggested equation to determine the design width is $B=1.235Q^{064}$ for less than $300m^3/sec$ of design flood. and when B and A are defined as a design width and a watershed area, respectively. the recommended equation is $B=8.794A^{0.56}$ for less than $10km^2$ of watershed area.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.5
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• pp.307-313
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• 2013

This paper presents a simulation for passenger ship evacuation considering determination of evacuating direction based on walking direction potential function. In order to determine walking direction of a passenger, his/her position in two dimensional plane was adopted as a design variable, and fixed boundaries such as walls and obstacles were adopted as constraints. To solve this optimum problem, a walking direction potential function was adopted as an objective function. This potential function was configured as a kind of penalty function and it contained two components. One is a potential function concerned with the distance to the destination, and other is a potential function based on the effect of walls and obstacles. To determine evacuating direction, this problem was solved by minimizing the walking direction potential function every unit time during the simulation. The crowd behavior of the passenger consisted of the flock behavior, a form of collective behavior of a large number of interacting passengers with a common group. With the proposed algorithm, the test problems in International Maritime Organization, Maritime Safety Committee/Circulation 1238(IMO MSC/Circ.1238) were implemented and the direction of passengers and total evacuation time was analyzed.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.76-83
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• 2002

In this paper, we developed the real-time automation program for the immunity test according to the determination of the EUT image, and analyzed the image of standard PC monitor and the monitor image affected by the electromagnetic field. The image change detection algorithm was realized for the real-time determination of the malfunction, and we attempted to obtain the consistent results for the electromagnetic immunity measurement. We showed the possibility to determine the immunity of the PC monitor and other equipment by performing the image change detection of EUT, and the experimental results for the EUT immunity determination of EMS (Electro-Magnetic Susceptibility, IEC 61000-4-3) are also proposed in line with the international standard and domestic trends.