• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.7-22
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• 2021

In this paper, we describe the results of the docking phase test in the ground environment of the rendezvous/docking technology verification satellite under development for the first time in Korea. rendezvous/docking technology is a high-level technology in space technology, which is also very important for accessing and performing tasks on relative objects in space orbit. In this paper, we describe the ground test results that the chaser finally docks the fixed target using an air bearing device. Based on the thrust control algorithm in the docking phase and the relative object recognition and relative distance estimation algorithm using visual-based sensors validated in this paper, we intend to use them for later expansion to rendezvous/docking algorithms in three-dimensional space for testing in space.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.45-51
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• 2008

Due to recent increases of typhoon damages primarily owing to heavy rainfall and stron wind, estimation and analysis of a typhoon's influence has become more important. In this perspective, the statistical models to estimate the rainfall rate during a typhoon were presented in this paper. Central pressure of the typhoon is modeled to be the primary parameter affecting typhoon rainfall rate while relative angle and distance between the center of typhoon and the specific location for observation are secondary variables. Comparisons between the estimated rainfall rate of these models and the observed value in the duration of Typhoon NARI(2007) were analyzed to confirm the availability of these models. The result shows that the present statistical models can estimate typhoon-induced rainfall around Korean Peninsular to some extent.

• Korean Journal of Poultry Science
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• v.23 no.4
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• pp.177-183
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• 1996

This study was conducted to analyze genetic characteristics of Korean Native Chicken three lines classified on the basis of the feather color and appearance (Red, Yellow, and Black) using DNA fingerprinting method. To estimate the genetic relatedness among breeds and similarities within breeds, we collected blood samples from Korean Native Chicken (KNC), Rhode Island Red (RIR), White Leghorn (WL), and Cornish(CN) and obtained genomic DNA from the blood of 10 individuals randomly selected within the breeds and lines. The genomic DNA samples were digested with restriction enzymes (Hinf J, Hae Ill) and hybridized with various probes (Jeffreys' probes 33.15, 33.6 and M13) after Southern transfer. Genetic similarities within breeds were characterized by band sharing (BS) value, estimated by the DFP band pattern between the pair of lanes. BS values within WL, RIR, and KNC were 0.82, 0.70 and 0.56, respectively. Relative genetic diversity (BS value) of KNC was higher than those two breeds (WL, RIR). Estimation of genetic similarity between KNC lines and control breed (RIR) was 0.32, whereas similarity within KNC lines (6 groups) was 0.50. In this analysis, KNC was showed to have a highly genetic diver-sity at the DNA level, and to be closer in genetic distance to RIR (0.67) than any other breeds.

• Journal of Astronomy and Space Sciences
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• v.33 no.1
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• pp.37-44
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• 2016

This paper presents an algorithm for Real-Time Orbit Determination (RTOD) of navigation satellites for the Korean Regional Navigation Satellite System (KRNSS), when the navigation satellites generate ephemeris by themselves in abnormal situations. The KRNSS is an independent Regional Navigation Satellite System (RNSS) that is currently within the basic/preliminary research phase, which is intended to provide a satellite navigation service for South Korea and neighboring countries. Its candidate constellation comprises three geostationary and four elliptical inclined geosynchronous orbit satellites. Relative distance ranging between the KRNSS satellites based on Inter-Satellite Ranging (ISR) is adopted as the observation model. The extended Kalman filter is used for real-time estimation, which includes fine-tuning the covariance, measurement noise, and process noise matrices. Simulation results show that ISR precision of 0.3-0.7 m, ranging capability of 65,000 km, and observation intervals of less than 20 min are required to accomplish RTOD accuracy to within 1 m. Furthermore, close correlation is confirmed between the dilution of precision and RTOD accuracy.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.286-293
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• 2005

In soft ground the settlement criterion usually governs. Therefore, it is very important not only reasonable assessment of the allowable bearing capacity of the soil but also reasonable assessment of settlement. In the previous studies by many other researchers, load concentration ratio and settlement reduction factor are usually proposed for estimating the settlement of granular compaction piles. In the previous studies, the reinforced ground with granular compaction piles is simplified as composite ground and the analysis is performed with in the basis of this assumption. However, the lateral deformation of granular compaction pile could not be considered and only the relative vertical strength between pile and soils could be considered in the analysis. In this study, a method adapting the Tresca failure criterion is proposed for calculating settlement of granular compaction pile. Proposed method can be considered the strength of pile material, pile diameter, installing distance of pile and the deformation behavior of vertical and horizontal directions of pile. In the presented study, large-scale field load test is performed and the results are described. Also, predictions of settlements from the proposed method are compared with the results of the load test. In addition, a series of parametric study is performed and the design parameters are analyzed.

• Current Optics and Photonics
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• v.2 no.2
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• pp.119-124
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• 2018

The errors in retrieved aerosol backscattering coefficients due to different lidar ratios are analyzed quantitatively in this paper. The actual calculation shows that the inversion error of the aerosol backscattering coefficients using the Fernald backward-integration method increases with increasing inversion distance. The greater the error in the lidar ratio, the faster the error in the aerosol backscattering coefficient increases. For the same error in lidar ratio, the smaller actual aerosol backscattering coefficient will get the larger relative error of the retrieved aerosol backscattering coefficient. The errors in the lidar ratios for dust or the cirrus layer have great impact on the retrievals of backscattering coefficients. The interval between the retrieved height and the reference range is one of the important factors for the derived error in the aerosol backscattering coefficient, which is revealed quantitatively for the first time in this paper. The conclusions of this article can provide a basis for error estimation in retrieved backscattering coefficients of background aerosols, dust and cirrus layer. The errors in the lidar ratio of an aerosol layer influence the retrievals of backscattering coefficients for the aerosol layer below it.

• Membrane and Water Treatment
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• v.13 no.5
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• pp.219-225
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• 2022

5th Assessment Report of the Intergovernmental Panel on Climate Change Weather (AR5) predicts that recent severe hydrological events will affect the quality of water and increase water pollution. To analyze changes in water quality due to future climate change, input data (precipitation, average temperature, relative humidity, average wind speed, and solar radiation) were compiled into a representative concentration curve (RC), defined using 8.5. AR5 and future use are calculated based on land use. Semi-distributed emission model Calculate emissions for each target period. Meteorological factors affecting water quality (precipitation, temperature, and flow) were input into a multiple linear regression (MLR) model and an artificial neural network (ANN) to analyze the data. Extensive experimental studies of flow properties have been carried out. In addition, an Acoustic Doppler Velocity (ADV) device was used to monitor the flow of a large open channel connection in a wastewater treatment plant in Ho Chi Minh City. Observations were made along different streams at different locations and at different depths. Analysis of measurement data shows average speed profile, aspect ratio, vertical position Measure, and ratio the vertical to bottom distance for maximum speed and water depth. This result indicates that the transport effect of the compound was considered when preparing the hazard analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1283-1289
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• 2013

The purpose of this study is to find the new method for estiming the spatial variations in a light source with utilizing the optical fiber sensory system. With this aim, firstly the asymmetry in the beam profile of a light source is evaluated by using the tipped optical fiber with 0, 10, 20, 30, 40, 45-degree angle. Secondly the variation of position in a light source is estimated by adjusting the relative position between the light source unit (XYZ stage, LED, Optical fiber) and the receiver unit (Photodiode, XYZ stage). Our experimental results show that the spatial variation of a light source can be resolved in terms of the variations in beam profile with varying the tip angle of an optical fiber and adjusting the relative distance between the light source unit and the receiver.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.166-175
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• 1989

In this paper, we present a method which is based on the concept of the rotation of subspaces. This method is highly related to the angle (or distance) between subspaces arising in many applications. An effective procedures is first derived for finding the optimal transformation matrix which rotates one subspace into another as closely as possible in the least squares sense , and then this algorithm is applied to the solution to general direction-of-arrival estimation problem of multiple broadband plane waves which may be a mixture of incoherent, partially coherent or coherent. In this typical application, the rotation of signal subspaces (ROSS) algorithm is effectively developed to achieve the high performance in the active systems for the case in which the noise field remains invariant with the measurement of the array spectral density matrix (or data matrix). It is not uncommon to observe this situation in sonar systems. The advantage of this techniques is not to require the preliminary processing and spatial prefiltering which is used in Wang-Kaveh's CSS focusing method. Furthermore, the array's geometry is not restricted. Simulation results are presented to illustrate the high performance achieved with this new approach relative to that obtained with Wang-Kaveh's CSS focusing method for incoherent sources and forward-backward spatial smoothed MUSIC for coherent sources including the signal eigenvector method (SEM).

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.3 s.303
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• pp.99-106
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• 2005

Instantaneous Frequency(IF) of Doppler signals is used to get the information of relative velocity and miss distance between a missile and the corresponding target. Though Short-Time Fourier Transform(STFT) is mainly used to estimate IF, it has many errors in wide band signals where frequency changes sharply. Because it has a fixed window in time and frequency axes. This paper deals with IF estimation of Doppler signal using a Continuous Wavelet Transform(CWT) which has adaptive window in time and frequency axes. The proposed method is able to estimate IF regardless of frequency changes because it has a narrow window in high frequency band and a wide window in low frequency band. The experimental results demonstrate that the proposed method outperforms STFT in estimating IF.