• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.473-478
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• 2003

This study was conducted to clarify the effects of duck free-ranging time on the growth and behavior patterns of duck, pH and dissolved oxygen of irrigation water, and growth and yield of the rice plants in paddy fields. Two paddy fields with each 5 aye were used for 12 hours duck free-ranging plot (12HFR) and 24 hours duck free-ranging plot(24HFR). Body weight gain of the duck was not different between 12HFR and 24HFR. Eating and feather grooming behavior in the 12HFR were significantly longer than those of 24HFR, but other behavior patterns were not so. Working behavior and activities of duck in paddy fields tended to be longer in the 12HFR than in 24HFR. However, any difference was not found on staying time of duck in paddy fields. Although it was not statistically significant, pH and dissolved oxygen of irrigation water tended to be higher in the 12HFR than in 24HFR. The plant height of rice in the 12HFR was significantly shorter than that of 24HFR during the latter half period. The number of tillers per hill was significantly increased in the 24HFR than in 12HFR. The shoot dry weight of rice in the 12HFR was significantly less than in the 24HFR during the heading stage of rice plant, but the root dry weight was not different. The number of spikelets per panicle was significantly less in the 12HFR than in 24HFR, however the percentage of ripened grains was significantly higher in the 12HFR. The yield of rice was not significantly different between the treatments. In conclusion, the free-ranging time of duck for 12 hours in paddy fields promoted eating and working behavior of the ducks. Free-ranging time did give effects on rice traits such as the number of tillers per hill, plant height, shoot dry weight of the rice plant, and spikelet number and percentage of ripened grain. However, the duck growth, pH and dissolved oxygen of irrigation water, and paddy rice yield were not affected by duck free-ranging time. These results might suggest that almost same effect as in 24 hours of free-ranging can be obtained with only 12 hours of free-ranging in daytime.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.172-175
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• 2016

Time of Flight(ToF) LiDAR(Light Detection And Ranging) technology has been used for distance measurement and object detection by measuring ToF time information. This technology has been evolved into higher precision measurement field such like autonomous driving car and terrain analysis since the retrieval of exact ToF time information is of prime importance. In this paper, as a accuracy indicator of the ToF time information, timing jitter was measured and analyzed through Single-Shot LiDAR system(SSLs) mainly consisting of 1.5um wavelength MOPA LASER, InGaAs Avalanche Photodiode(APD) at 31M free space environment. Additionally, we applied spline interpolation and multiple-shot averaging method on measured data through SSLs to improve ToF timing information.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1217-1227
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• 2012

There are several antenna calibration methods, so-called 3-Antenna Method, Standard Site Method, and Standard Antenna Method which measure the antenna gains or antenna factors. These methods yield the free space or quasi free space antenna gains in only the frequency domain. In this paper, an antenna calibration method using the time domain in the open area test site is discussed. The reflected waves due to the ground are traced in the time domain. After they are removed by the time gating function of network analyzer, the free space transmission coefficient $S_{21}$ is extracted. Such a way is applied to the broad band horn antenna ranging 1 GHz to 18 GHz, and the free space gains are obtained by Friis transmission equation. The method is checked by Standard Site Method in open area test site. The results show comparatively good agreement except for 18 GHz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.25-29
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• 1997

In this thesis, we construct the microrobot succor system and navigate the real-time path planning and visual tracking of each robot. The system consists robots, vision system and a host computer. Because the robots are free-ranging mobile robot, it is needed to make and gallow the path. The path is planned and controlled by a host computer, ie. Supervisory control system. In path planning, we suggest a cost function which consists of three terms. One is the smoothness of the path, another is the total distance or time, and the last one is to avoid obstacles. To minimize the cost function, we choose the parametric cubic spline and update the coefficients in real time. We perform the simulation for the path planing and obstacle avoidance and real experiment for visual tracking

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.421-433
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• 2002

This study was conducted to develope a simple, rapid and solvent-free solid-phase microextraction(SPME) procedure for extracting three organochlorine, one triazine and nine organophosphorus pesticides from water. The optimal conditions of SPME for analyses of organochlorine pesticides were obtained at $250^{\circ}C$ of desorption temperature, 45 minutes of equilibrium time, pH 6 and NaCl 0% addition using $100{\mu}m$ polydimethylsiloxane fiber and those of triazine and organophosphorus pesticides were obtained at $270^{\circ}C$ of desorption temperature, 60 minutes of equilibrium time, pH 6 and NaCl 0% addition using $100{\mu}m$ polydimethylsiloxane fiber. This method showed good lineality for organochlorine pesticides between 0.0001 and $10{\mu}g/L$ with regression coefficients ranging 0.9986~0.9992 and for triazine and organophosphorus pesticides between 0.01 and $10{\mu}g/L$ with regression coefficients ranging 0.9867~0.9998.

• Advances in aircraft and spacecraft science
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• v.10 no.4
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• pp.303-315
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• 2023

The primary goal of this research is to investigate flow separation phenomena using various turbulence models. Also investigated are the effects of free-stream turbulence intensity on the flow over a NACA 0018 airfoil. The flow field around a NACA 0018 airfoil has been numerically simulated using RANS at Reynolds numbers ranging from 100,000 to 200,000 and angles of attack (AoA) ranging from 0° to 18° with various inflow conditions. A parametric study is conducted over a range of chord Reynolds numbers for free-stream turbulence intensities from 0.1 % to 0.5 % to understand the effects of each parameter on the suction side laminar separation bubble. The results showed that increasing the free-stream turbulence intensity reduces the length of the separation bubble formed over the suction side of the airfoil, as well as the flow prediction accuracy of each model. These models were used to compare the modeling accuracy and processing time improvements. The K- SST performs well in this simulation for estimating lift coefficients, with only small deviations at larger angles of attack. However, a stall was not predicted by the transition k-kl-omega. When predicting the location of flow reattachment over the airfoil, the transition k-kl-omega model also made some over-predictions. The Cp plots showed that the model generated results more in line with the experimental findings.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.105-116
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• 2017

Several wireless localization algorithms are evaluated for the IR-UWB-based indoor location with the assumption that the ranging measurements contain the channelwise Non-Calibration Error (NCE). The localization algorithms can be divided into the Model-free Localization (MfL) methods and Model-based Kalman Filtering (MbKF). The algorithms covered in this paper include Iterative Least Squares (ILS), Direct Solution (DS), Difference of Squared Ranging Measurements (DSRM), and ILS-Common (ILS-C) methods for the MfL methods, and Extended Kalman Filter (EKF), EKF-Each Channel (EKF-EC), EKF-C, Cubature Kalman Filter (CKF), and CKF-C for the MbKF. Experimental results show that the DSRM method has better accuracy than the other MfL methods. Also, it demands smallest computation time. On the other hand, the EKF-C and CKF-C require some more computation time than the DSRM method. The accuracy of the EKF-C and CKF-C is, however, best among the 9 methods. When comparing the EKF-C and CKF-C, the CKF-C can be easily used. Finally, it is concluded that the CKF-C can be widely used because of its ease of use as well as it accuracy.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.6
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• pp.681-691
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• 2011

The size distributions of smoke particles from fire are prerequisite for the studies on fire detection and adverse health effects. Above the flame of the fire, coagulation dominates and the smoke particles grow from 1 to 50 nm up to 100 to 3,000 nm, sizes ranging from the free-molecular regime to the continuum regime. The characteristics of the agglomeration of the smoke particles are well known, independently for each of the free-molecular and continuum regimes. However, there are not many systematic studies in the entire regime by the complexity of the mechanisms. The purpose of this work is to find the characteristics of the development of the size distribution of smoke particles by agglomeration in the entire size range covering the free-molecular regime, via transition regime, to the near-continuum and continuum regime for each variation of parameters such as fractal dimension, primary particle size and dimensionless coagulation time. In this work, the dynamic equation for the discrete-size spectrum of the particles was solved using a nodal method based on the modification of a sectional method. In the calculation, the collision frequency function for the entire regime, which is derived by using the concept of collision volume and general enhancement function, was applied. The self-preserving size distribution for the entire regime is compared with the ones for the free-molecular or continuum regimes for each variation of the parameters.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3099-3102
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• 2010

A label-free DNA detection method was developed for a simple electrochemical DNA sensor with a short assay time. Self-assembled monolayers of peptide nucleic acid were used as a probe on gold electrodes. The formation of the self-assembled monolayers on the gold electrodes was successfully checked by means of cyclic voltammetry. The target DNA, hybridized with peptide nucleic acid, can be detected by the anodic peak current of ferrocene dendrimers, which interact electrostatically with the target DNA. This anodic peak current was measured by square wave voltammetry at 0.3 V to decrease the detection limit on the order of the nanomolar concentrations. As a result, the label-free electrochemical DNA sensor can detect the target DNA in concentrations ranging from 1 nM to $1\;{\mu}M$ with a detection limit of 1 nM.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.7-11
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• 2015

The present study investigates the impact shear strength of thermal aged Sn-3Ag-0.5Cu lead-free solder joints at impact speeds ranging from 0.5 m/s to 2.5 m/s. The specimens were thermal aged for 24, 100, 250 and 1000 hours at $100^{\circ}C$. The experimental results demonstrate that the shear strength of the solder joint decreases with an increase in the load speed and aging time. The shear strength of the solder joint aged averagely decreased by 43% with an increase in the strain rate. For the as-reflowed specimens, the mode II stress intensity factor ($K_{II}$) of interfacial IMC between Sn-3.0Ag-0.5Cu and a copper substrate also was found to decrease from $1.63MPa.m^{0.5}$ to $0.97MPa.m^{0.5}$ in the speed range tested here. The degradations in the shear strength and fracture toughness of the aged solder joints are mainly caused by the growth of IMC layers at the solder/substrate interface.