• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.348-356
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• 2005

Water quality sampling surveys and continuous measurement of flow were conducted to identify wastewater flow characteristics for representative catchment of O and M treatment basins in A city. For HS-1 station representing commercial area, wastewater flow rises in the beginning of office-working hours, moves up and down within narrow range, and lasts till office-leaving hour, and falls gradually reflecting worker's returning home. However, in HS-2 station representing residential area, wastewater flow has two peaks, which are before office-going hour and after office-leaving hour. In residential area, the flow rate of weekends is higher than that of weekdays because it reflects population, being not contributed to generate wastewater during the working hours of weekdays, stay home and produce wastewater for weekends period. To determine the priority for rehabilitation of sewer system, infiltration rate was computed by dividing infiltration flow by mean diameter and total length of sewer, and HS-1 station ranked the first.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2664-2669
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• 2011

We proposed a new method to improve the resolution of far object image in curving effective integral imaging system. Basically, the curving effective integral imaging(CEII) system can improve the resolution of the reconstructed images with an increased sampling rate of elemental images. However, in the case when an object located far from the lenslet array is picked up, the low resolution of the reconstructed images of the far object has been a primary problem because the sampling rate is very low. In order to solve this drawback, by using the direct pixel mapping(DPM) method the EIA picked up from a far object is transformed into a new EIA that virtually looks like the EIA picked up from the object originally located close to the lenslet array. From this new EIA, highly resolution-enhanced images of far object could be reconstructed in the CEII system. To show the feasibility of the proposed method, simulation results are compared with the conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.794-806
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• 2004

This paper deals with correction of frequency offset and analysis of quantization angle noise in the IEEE 802.1la OFDM system. The rotation phase per symbol due to the carrier frequency offset is estimated from auto-correlation of the short Preambles, which are over-sampled for the reduction of noise in OFDM signals. The pilot signals are introduced to estimate the rotation phase per OFDM symbol due to estimation error of the carrier frequency offset and the sampling frequency onset. During the estimation and correction of the frequency onsets, a CORDIC processor and a look-up table are used for the conversion between a rotation phase and its complex number. Being calculated by a limited number of bits in the CORDIC processor and the look-up table, the rotation phase and its complex number have quantization angle errors. The quantization errors are analyzed as SNR (signal to noise ratio) due to the quantization bit numbers. The minimum bit number is suggested to meet the specification of IEEE 802.1la properly. Finally, the quantization errors are evaluated through simulations on number of quantization bits and SNR of received signals.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.59-65
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• 2011

Korea DMB Service is popularized, and is used by many users. But latest display devices compared to the DMB content resolution support higher resolution and a variety of video resampling technologies has been used. Generally, subjective video quality is determined by object recognition rate in video, and increased as the edge space between objects are more clear. An edge is the boundary between an object and the background, and indicates the boundary between overlapping objects. the predicted direction in intra prediction used in H.264/AVC has the similarity up to 80% for the edge information. In the study, we propose an effective up-sampling mothed using the edge information that is extracted for the relationship between the intra prediction data and the DCT coefficient data of H.264 video encoding.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.417-428
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• 1999

The measurement of VOSCs(volatile organic sulfur compounds) in the air is nowadays a very important environmental research field. It is, however, very difficult because the concentration of the VOSC in ambient air is usually very low and the high reactivity makes it difficult to keep in container without loss of recovery. In this study, sampling method with cryogenic preconcentration is evaluated for analysis of atmospheric VOSC such as $CH_3SH,\;CH_3CH_2SH,\;CH_3SCH_3,\;CS_2,\;CH_3SSCH_3,\;CH_3SCH_2SCHA_3,\;and\;C_2H_5SSC_2H_5$ analyzed by GC-MS or GC-FID. Repeatabilities of measurement accompanied with preconcentration for 3-successive runs were in the range of 0.2~1.0% as a relative standard deviation. Stabilities up to 13 days were measured in 6 L canister and 10 L tedlar bag filled with VOSCs in ppb level. Higher stability was observed in tedlar bag as compared to canister with glass coated inner walls, and thiol compounds show dramatic losses in canister within 2~3 days. It is found that recovery over 70% was obtained in a week for all tested VOSCs when the compounds from ambient air matrix were stored in tedlar bag. It is also found that the stabilities of VOSCs are depending on humidity and coexisting compounds in matrix gas due to sample adsorption onto inner surface and reactivity. The results indicate the possibility and limitations of VOSC analysis in ambient air using container sampling method with cryogenic preconcentration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.67-73
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• 1985

In Digital Terrain Model(DTM), more accurate data acquisition method is of importance. This paper has the purpose of accuracy analysis of progressive sampling method, one of data acquisition method. Especially, The following in accuracy analysis are compared and analyzed. -Comparison and analysis for position error between the digital contour lines using digital terrain model and the conventional contour lines using A-10 Plotter. -Analysis for height error of interpolation points according to application of progressive sampling method. For above numerical tests, Computer Program related to auto-carto of contour lines was made up. As a result of tests, threshold and sampling criterion have close of mutual relation to accuracy. Particularly, it was found that auto-carto of contour lines-threshold of 1.0 m and standard criterion-almost concurred in conventional contour lines.

• School Mathematics
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• v.8 no.4
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• pp.441-463
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• 2006

The purpose of this research is to investigate how elementary school students execute sampling with what designs in order to gather information under a situation that requires collecting data and information about their household and everyday life, and to examine how they use tools, including table or graph, etc., in order to perform efficient analysis of data and information they surveyed, also what results they acquire. To test this, the researcher set up a situation in advance that requires collecting data, and, under this circumstance, the researcher instructed and guided school students to look for methods how to design and survey in order to gather data by having them discuss tasks, involving small groups or entire class, and seek its solutions by themselves through trial and errors. The results from surveys revealed that a lesson, which will have students do sampling and arrange statistical data and analyze the results, was possible to carry out in the class of 6th grade of elementary school.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.477-484
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• 2016

In general, $CH_4$ concentrations generated in combustion facilities are known to be ppm units. In most cases, $CH_4$ samples are collected in Tedlar bags and transported to laboratories for analysis. Considering this fact, in the present study, an attempt was made to find out how long samples can be stored in cases where they are kept in bags and transported as a preliminary study for sampling. According to the results of the experiment using simulated gases (1 ppm, 5 ppm, 10 ppm) in Tedlar bag, $CH_4$ was safe up to 240 hr which is the full time. In the case of simulated gases are containing 4 kind gases ($N_2$, $CO_2$, $CH_4$, and $N_2O$). Field samples (samples of obtained by collecting combustion facilities' exhaust gases) are known to contain highly reactive substances (for example NOx, SOx, and VOCs) and may affect each other. In the present study, one site sample was secured from each of a bituminous coal combustion facility and an LNG combustion facility and whether the concentrations of $CH_4$ gas would change over time (24 hr, 96 hr, 144 hr, 192 hr) was checked. Since site samples could not be analyzed on the day of collection, an experiment was started 24 hr after the time point of sampling to analyze the samples. As with the results of analysis of the simulated gas (240 hr), the results of analysis using the site sample indicated that it could be stored for the full study period 192 hr. Therefore, it was judged that if 192 hr would be taken after sampling before the sample would be analyzed, the concentration value should be reliable.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.432-438
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• 2019

In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two $LaBr_3:Ce$ detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV ${\gamma}$ photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the $^{152}Gd-2_1^+$ state form ${\beta}^+$ decay of $^{152}Eu$ source is measured. The measured lifetime is $45.3({\pm}5.0)ps$, very close to the value of the National Nuclear Data Center (NNDC: $46.2({\pm}3.9)ps$). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.48-56
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• 2018

Due to the growing concerns of energy resource depletion and environmental destruction, the mass production of microalgae has been studied. The scale-up of a photobioreactor (PBR) is required for the mass production of biomass. In this paper, the geometric parameters and oxygen transfer rate (OTR) are considered, to scale up a flat panel photobioreactor (FP PBR). The PBR is designed using the goal-driven optimization (GDO) method to accomplish the scale-up. The local sensitivity of each output parameter with respect to the input parameter is analyzed through the design of experiment (DOE), and the design candidates are evaluated with the screening sampling method. The volumetric mass transfer coefficient is measured by the dynamic method.