• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.350-357
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• 2017

Purpose: In-situ monitoring of water quality is fundamental to most environmental applications. The high cost and long delays of conventional laboratory methods used to determine water quality, including on-site sampling and chemical analysis, have limited their use in efficiently managing water sources while preventing environmental pollution. The objective of this study was to develop an on-site water monitoring system consisting mainly of an Arduino board and a sensor array of multiple ion selective electrodes (ISEs) to measure the concentration of $NO_3$ ions. Methods: The developed system includes a combination of three ISEs, double-junction reference electrode, solution container, sampling system consisting of three pumps and solenoid valves, signal processing circuit, and an Arduino board for data acquisition and system control. Prior to each sample measurement, a two-point normalization method was applied for a sensitivity adjustment followed by an offset adjustment to minimize the potential drift that could occur during continuous measurement and standardize the response of multiple electrodes. To investigate its utility in on-site nitrate monitoring, the prototype was tested in a facility where drinking water was collected from a water supply source. Results: Differences in the electric potentials of the $NO_3$ ISEs between 10 and $100mg{\cdot}L^{-1}$ $NO_3$ concentration levels were nearly constant with negative sensitivities of 58 to 62 mV during the period of sample measurement, which is representative of a stable electrode response. The $NO_3$ concentrations determined by the ISEs were almost comparable to those obtained with standard instruments within 15% relative errors. Conclusions: The use of the developed on-site nitrate monitoring system based on automatic sampling and two-point normalization was feasible for detecting abrupt changes in nitrate concentration at various water supply sites, showing a maximum difference of $4.2mg{\cdot}L^{-1}$ from an actual concentration of $14mg{\cdot}L^{-1}$.

• Journal of Korean Society of Forest Science
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• v.17 no.1
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• pp.35-42
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• 1973

Deciduous trees grown naturally in the forest of Korea usually have an irregular Lee-form and their utility has been decreased. In Korea, most of the deciduous stands are distributed in the hinterland. A shortage of the total growing stock made utilization of them necessary in this country even though some difficulties to be cutted and transported are accompanied. Therefore, this study was conducted to select the suitable sampling method for surveying them. The results investigated are as follows. 1. Three locations being 10 hectares in each location for the plots were chosen and surveyed with six $20m{\times}50m$ rectangular sample plots by four types of sampling method below. And the result is shown in Table 1. A. Random sampling by grids B. Random sampling by co-ordinates C. Systematic line plot. D. Sub-sampling 2. One hundred and fifty hectares from all plots were sectioned through the application of aerial photography scaled of 1 : 15,000. The author divided forest types according to diameter class and crown density with mirror stereoscope. The forest types were divided into three classes. Seven sample plots from the area of 150 hectars are systematically arranged and the results investigated on the circular sample point of 0.1 hectare are shown in Table 4. 3. There were no significant differences between results by sampling method and by diameter measurement method (population mean) as shown in Table 3. 4. Random sampling by grid and systematic line plot are better than others. 5. There are more over-estimated values when the circular sample point is used than where the rectangular sample point. 6. As forest stands are irregular, smaller number of sample points will make many errors.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.2
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• pp.21-26
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• 2005

From on the machining center cutting work of 5534, the characteristics such as spindle speed and feed speed fir the third point height, average spacing of roughness peaks, bearing ratio, center line average, ten point height. experiments is roughness for sampling length determine to measuring length of cutting feed speed 200, 400, 600, 800mm/min and spindle speed 800, 1000, 1200, 1400rpm. Third point height is spindle speed with most suitable cutting condition 1000rpm. Third point height is feed speed with most suitable cutting condition 400mm/min. Average spacing of roughness peaks are spindle speed with most suitable cutting condition feed speed increased to average spacing of roughness Peaks are increased. Spindle speed increased to average spacing of roughness peaks are decreased. Bearing ratio is spindle speed with feed speed increased to bearing ratio decreased. Center line average is spindle speed with most suitable cutting condition at 1200rpm feed speed with most suitable cutting condition at 200mm/min to cutting foe roughness suddenly decreased. Ten point height is spindle speed with most suitable cutting condition 1200rpm at ten point height cutting face roughness to decreased and feed speed with most suitable cutting condition 800mm/min at ten point height cutting face roughness to decreased.

• Journal of KIISE:Software and Applications
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• v.36 no.11
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• pp.947-954
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• 2009

This paper proposes a novel method that reconstructs a surfel-based object by using visual hull from multiple images. The surfel is a point primitive that effectively approximates point-set surface. We create the surfel representation of an object from images by combining the LDC(Layered Depth Cube) surfel sampling with the concept of visual hull that represents the approximated shape from input images. Because the surfel representation requires relatively smaller memory resources than the polygonal one and its LDC resolution is freely changed, we can control the reconstruction quality of the target object and acquire the maximal quality on the given memory resource.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.897-903
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• 2010

This paper presents a response surface method(RSM) with Latin Hypercube Sampling strategy, which is employed to optimize a magnet pole shape of large scale BLDC motor to minimize the cogging torque. The proposed LHS algorithm consists of the multi-objective Pareto optimization and (1+1) evolution strategy. The algorithm is compared with the uniform sampling point method in view points of computing time and convergence. In order to verify the developed algorithm, a 6 MW BLDC motor is simulated with 4 design parameters (arc length and 3 variables for magnet) and 4 constraints for minimizing of the cogging torque. The optimization procedure has two stages; the fist is to optimize the arc length of the PM and the second is to optimize the magnet pole shape by using the proposed hybrid algorithm. At the 3rd iteration, an optimal point is obtained, and the cogging torque of the optimized shape is converged to about 14% of the initial one. It means that 3 iterations aregood enough to obtain the optimal design parameters in the program.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.48-52
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• 2001

In this paper presents an accurate AFM used that is free from the Z-directional distortion of a servo actuator is described. Two mathematical correction methods by the in-situ self-calibrationare employed in this AFM. One is the method by the integration, and the other is the method by inverse function of the calibration curve. The in situ self-calibration method by the integration, the derivative of the calibration curve function of the PZT actuator is calculated from the profile measurement data sets which are obtained by repeating measurements after a small Z-directional shift. Input displacement at each sampling point is approximately estimated first by using a straight calibration line. The derivative is integrated with reference to the approximate input to obtain the approximate calibration curve. Then the approximation of the input value of each sampling point is improved using the obtained calibration curve. Next the integral of the derivative is improved using the newly estimated input values. As a result of repeating these improving process, the calibration curve converges to the correct one, and the distortion of the AFM image can be corrected. In the in situ self-calibration through evaluating the inverse function of the calibration curve, the profile measurement data sets were used during the data processing technique. Principles and experimental results of the two methods are presented.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.67-75
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• 2011

This paper presents a new test technique for evaluating performance of vehicle detectors with interval estimation, not the conventional point estimation, for presenting statistical confidence interval. The methodology is categorized into three parts; sampling plan, analysis on the characteristic of evaluation indices, and the expression of evaluation results. Even though many statistical sampling plans exist, stratified random sampling is regarded as the most appropriate one, considering the detector performance characteristics that varies with traffic, illumination, and meteorological conditions. No magic bullet exists for evaluation index for detector evaluation, hence the characteristics of evaluation indices were thoroughly analyzed and a reasonable process for choosing the best evaluation index is proposed. Finally, the methodology to express the result of detector evaluation for the entire evaluation period and individual analysis interval is represented, respectively. To overcome the existing drawbacks in point estimation, interval estimation by which statistical confidence interval can be represented is introduced for enhancing statistical reliability of traffic detector evaluation. This research can make vehicle detector scheme improve one step forward.

• Computational Structural Engineering
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• v.7 no.1
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• pp.109-116
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• 1994

In this paper, various reliability analysis methods for calculating a probability of failure are investigated for their accuracy and efficiency. Crude Monte Carlo method is used as a basis for the comparison of various numerical results. For the sampling methods, Importance Sampling method and Directional Simulation method are considered for overcoming a drawback of Crude Monte Carlo method. For the approximate methods, conventional Rackwitz-Fiessler method. 3-parameter Chen-Lind method, and Rosenblatt transformation method are compared on the basis of First order reliability method. As a Second-order reliability method, Curvature-Fitting paraboloid method, Point-fitting paraboloid method, and Log-likelihood function method are explored in order to verify the accuracy of the reliability calculation results. These methods mentioned above would have some difficulty unless the limit state equation is expressed explicitly in terms of random design variables. Thus, there is a need to develop some general reliability methods for the case where an implicit limit state equation is given. For this purpose, Response surface method is used where the limit state equation is approximated by regression analysis of the response surface outcomes resulted from the structural analysis. From the application of these various reliability methods to three examples, it is found that Directional Simulation method and Response Surface method are very efficient and recommendable for the general reliability analysis problem cases.

• Journal of Environmental Science International
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• v.26 no.4
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• pp.467-481
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• 2017

This study sought to determine the changes in weather conditions in urban streets, along with conditions of traffic and roads in urban areas. The variations in weather conditions depending on traffic differed according to distance. First, the temperature difference measured by traffic results is as follows: T1 point $1.03^{\circ}C$, T2 point $1.04^{\circ}C$, T3 point $0.9^{\circ}C$, T4 point $1.01^{\circ}C$, and T5 point $0.31^{\circ}C$. The average difference between the measured temperatures by the point of measurement was $0.86^{\circ}C$. The changes in wind velocity according to traffic volume results of the measurements is T1 point 1.32 m/s, T2 point 0.80 m/s, T3 point 0.29 m/s, T4 point 0.04 m/s, and T5 point 0.09 m/s. The difference between the average wind speeds was 0.51 m/s and traffic jams caused substantial differences in distance. The relative humidity tended to be inversely proportional to temperature. The measurements results ares T1 point 2.29%, T2 point 2.67%, T3 point 2.47%, T4 point 2.16%, and T5 point 0.91% The difference between the average relative humidity was 7.3%. In case of independent sampling T test according to traffic volume, changes in wind velocity and temperature were directly proportional to the level of statistical significance(p<0.01). On the other hand, relative humidity tended to be inversely proportional; however, there was no statistical significance.

• Journal of Environmental Impact Assessment
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• v.16 no.6
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• pp.525-532
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• 2007

In order to establish and implement the total maximum daily load (TMDL) management plan in Korea, it is necessary to set the source units and calculate discharge loads for non-point source pollutants such as BOD, COD, SS, TN and TP. This study analysed the corelation between stormwater runoff characteristics and event mean concentrations (EMCs) of non-point source pollutants. As the result of the corelation analysis, we knew that all the antecedent dry days (ADD) and the rainfall correlated lowly with non-point source pollutants in the urban areas such as resident area, industrial area, business area, road area and parking area. Therefore, it is necessary to get all samples from stormwater starting point to stormwater ending point and standardize the sampling method of stormwater in order to obtain more accurate EMCs for landuse.