• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.1-8
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• 2003

Two types of ground-water sampling techniques for CFCs (chlorofluorocarbons) analysis, the cold-welded copper tube method and flame-sealed borosilicate glass ampule method, were compared and evaluated. CFCs concentrations by the copper tube method showed a poor reproducibility among triplicates whereas those by the glass ampule method showed a good agreement and relative standard deviations of triplicates were less than 5%. The poor reproducibility of the copper tube method appears to be attributed to the incomplete sealing in connection between faucets of wellhead and the sampling apparatus. The copper tube method also showed higher CFCs concentrations than the glass ampule method, which is more pronounced for CFC-11 than for CFC-12. The plastic tubings and rubber gasket of faucets in case of the copper tube method possibly contaminated the samples with CFC-11 and CFC-12. The potential of CFCs contamination for the glass ampule method was eliminated by using stainless steel and Nylon only and by connecting the sampling equipment directly to the main discharge pipe of wellhead. The validity of the glass ampule method were also verified by detecting very low level of CFCs for the ground-water sample which is old enough to have negligible CFCs.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.701-712
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• 2013

The e-learning industry status survey statistic provides information about the actual conditions of supply and demand of the e-learning industries. NIPA (National IT Industry Promotion Agency) has published the annual report of the survey results since 2004. Due to the 9th version of the KSIC (Korean standard industrial classification) revised in 2008, a refinement of the sampling design for the survey becomes necessary, especially that for the business demand sector. This article, based on the 9th revision of the KSIC, constructs a stratification of the target population used for the e-learning industry status survey on the business demand sector. Classification of strata in the business population is based on the industrial type and employment scale of business. Under the stratified population, we design a sampling scheme by using the power allocation method that enables us to satisfy a target coefficient of variation of each industrial stratum. In order to secure an accurate survey results based on the proposed sampling design, we consider the problem of calculating the design weights, derivation of parameter estimators, and formulas of their standard errors.

• Journal of IKEEE
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• v.24 no.1
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• pp.178-185
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• 2020

This paper proposes precise time synchronization-based synchronized sampling structure applied HW/SW platform for LAN-based protection of future digital substations. The integrated software of the proposed platform includes IEC 61850 protocol, IEEE 1588 precision time protocol and synchronized sampling structure. The proposed platform expected to provide a basis of an application of future distributed sensing data-based protection and control methods by providing synchronized measurement among IEDs. The implementation of the proposed HW/SW platform technique was performed using TMDXIDK572 multi-core/multi-processor evaluation module and its time synchronization performance and synchronized sampling function were confirmed through the performance tests.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.2
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• pp.87-96
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• 2019

Low power issue is one of the most critical problems in the Internet of Things (IoT), which are powered by battery. To solve this problem, various approaches have been presented so far. In this paper, we propose a method to reduce the power consumption by reducing the numbers of accesses into the flash memory consuming a large amount of power for on-chip software execution. Our approach is based on using cooperative logging structure to distribute the sampling overhead in single sensor node to adjacent nodes in case of rare-event applications. The proposed algorithm to identify event occurrence is newly introduced with negative feedback method by observing difference between past data and recent data coming from the sensor. When an event with need of flash access is determined, the proposed approach only allows access to write the sampled data in flash memory. The proposed event detection algorithm (EDA) result in 30% reduction of power consumption compared to the conventional flash write scheme for all cases of event. The sampled data from the sensor is first traced into the random access memory (RAM), and write access to the flash memory is delayed until the page buffer of the on-chip flash memory controller in the micro controller unit (MCU) is full of the numbers of the traced data, thereby reducing the frequency of accessing flash memory. This technique additionally reduces power consumption by 40% compared to flash-write all data. By sharing the sampling information via LoRa channel, the overhead in sampling data is distributed, to reduce the sampling load on each node, so that the 66% reduction of total power consumption is achieved in several IoT edge nodes by removing the sampling operation of duplicated data.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.7
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• pp.311-316
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• 2019

Classification problem is to predict the class to which an input data belongs. One of the most popular methods to do this is training a machine learning algorithm using the given dataset. In this case, the dataset should have a well-balanced class distribution for the best performance. However, when the dataset has an imbalanced class distribution, its classification performance could be very poor. To overcome this problem, we propose an over-sampling scheme that balances the number of data by using Conditional Generative Adversarial Networks (CGAN). CGAN is a generative model developed from Generative Adversarial Networks (GAN), which can learn data characteristics and generate data that is similar to real data. Therefore, CGAN can generate data of a class which has a small number of data so that the problem induced by imbalanced class distribution can be mitigated, and classification performance can be improved. Experiments using actual collected data show that the over-sampling technique using CGAN is effective and that it is superior to existing over-sampling techniques.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1682-1687
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• 2020

We study the problem of sampling a subset of nodes of graphs for bandlimited graph signals such that the signal values on the sampled nodes provide the most information in order to reconstruct the original graph signal. Instead of directly minimizing the reconstruction error, we focus on minimizing the upper bound of the reconstruction error to reduce the complexity of the selection process. We further simplify the upper bound by applying useful approximations to propose a low-weight greedy selection process that is iteratively conducted to find a suboptimal sampling set. Through the extensive experiments for various graphs, we inspect the performance of the proposed algorithm by comparing with different sampling set selection methods and show that the proposed technique runs fast while preserving a competitive reconstruction performance, yielding a practical solution to real-time applications.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1023-1030
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• 2020

We address the sampling set selection problem for arbitrary graph signals such that the original graph signal is reconstructed from the signal values on the nodes in the sampling set. We introduce a variation difference as a new indirect metric that measures the error of signal variations caused by sampling process without resorting to the eigen-decomposition which requires a huge computational cost. Instead of directly minimizing the reconstruction error, we propose a simple and fast greedy selection algorithm that minimizes the variation differences at each iteration and justify the proposed reasoning by showing that the principle used in the proposed process is similar to that in the previous novel technique. We run experiments to show that the proposed method yields a competitive reconstruction performance with a substantially reduced complexity for various graphs as compared with the previous selection methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.268-274
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• 2016

To find the location of a random noise source present in the three-dimensional space is required at least four microphones. Using four microphones distributed in a three-dimensional space, noise source imaging technique was applied and evaluated on their performance. To compensate resolution problem which comes from both the position of the sensor array is fixed and the sampling frequency is low, up-sampling technique and interpolation function were applied. Five different interpolation methods were applied such as zero-padding, zero-order hold, first-order hold, spline function, and random signal padding. The up-sampling rate were chosen by two, four, eight times, and counting up 16 times. As a result, it was possible to more accurately estimate the position of the noise source according to the higher of the up-sampling rate. It also found that the first-order hold and the spline function's performance were slightly falling relative to other methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2451-2459
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• 2009

The present study aimed to evaluate the accuracy of the blood glucose test with almost painless vacuum assisted auto-lancing technique. The blood glucose concentration measurements in the capillary blood sampled from the alternative (forearm) site were compared with the standard venous or finger sampling techniques. Capillary blood was sampled from both the left index finger and the forearm, followed by the venous blood sampling in 531 patients who visited the C University Hospital. Blood sugar test was performed for each blood samples for comparative analysis. Mean blood glucose concentration measured on the forearm was closer to the venous glucose level than that of the finger, but the difference was approximately 10 mg/dL small enough to ignore from the clinical point of view. The correlation coefficients of the measured blood glucose levels between finger and vein and between forearm and vein were 0.94 and 0.92, respectively (p<0.001). The blood glucose measurement on the forearm also well correlated with the finger, showing a correlation coefficient of 0.94, and both data were very much close to each other. Therefore, the blood sugar test on the alternative capillary blood sampling site such as forearm was accurate enough for clinical practice. The vacuum assisted auto-lancing technique on the alternative site would be of particular interest for the disease management of the chronic diabetes, since it induces almost no pain when sampling blood from the capillaries.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.845-852
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• 2020

The study aims to investigate the implementation of the internal quality assurance system (IQAS) on HEIs performance, mediated by financial management accountability. The commitment from foundation leadership on financial management accountability and their implications for HEIs' performance is also carefully examined. This study employs samples of 108 respondents from the leadership of private HEIs under Region IV Service Institutions. The purposive sampling, as a part of non-probability sampling was chosen as the sampling technique. Statistical data analysis conducted by use the structural equation model to test the hypothesis. The results reveal that the implementation of IQAS does not influence the financial management accountability, but it has an essential role on HEIs' performance. Moreover, foundation leadership's commitment has a significant positive effect on financial management accountability and HEIs' performance. Financial management accountability also has a significant positive effect on HEIs' performance. Financial management becomes important because the entire activities of HEIs should end with financial reporting. Therefore, financial and non-financial aspects are two interrelated and complementary aspects in the accreditation process. The findings of this study suggest that that performance measurement is very crucial as a part of the efforts to meet the general accountability requirement for organizations, particularly in HEIs.