• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1491-1497
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• 2009

Existing methods to measure are based on ToA (Timer of Arrival), RSS (Received Signal Strength), AoA(Angle of Arrival) and other methods. In this paper, we propose a compensation of ToA and RSS methods to measure more precisely the distance of nodes. The comparison experiments with the traditional ToA method show that the average error value of proposed method is reduced 30%. We believe that this proposal can improve location estimation of sensor nodes in wireless sensor networks.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.109-111
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• 2009

In this paper, we discuss how to design 2-wheeled mobile robot hard wares as reasonable and practical as possible. A segway type mobile robot consists of 2 wheels only, placed in parallel rather than horizon. 2-wheeled mobile robots make you overcome high cost and time consuming maintenance procedures of the robot by reducing the number of robot hardwares. The most challenging thing in a 2-wheeled mobile robot that has many more valid virtues than the traditional mobile robots is to make it balance itself whenever it stands still or goes forward. But balancing itself is not an easy matter and there are many researches and experiments on this issue. When researchers test theories on 2-wheeled mobile robots to improve its self balancing performance, they should consider how to design hard wares of that mobile robot. No matter how great those new theories are, if a testbed for those theories is not suitable, performance output would be poor and meaningless. In this point of view, to design a proper 2-wheeled mobile robot as a testbed is a very important issue with development of new theories. So we define 4 guide lines to design segway type mobile robots reasonably; about motor, battery, and MCU selection and shock-proof design with robust motor setting.

• Journal of Korean Elementary Science Education
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• v.23 no.3
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• pp.208-218
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• 2004

Many elementary school students have misconception related to dissolution and solution. Moreover, they usually fail to apply the results of the experiments in their science classes to their everyday life, and also have low science achievement. Therefore, they are not interested in science, and sometimes some of them are even afraid of it. The purposes of this study is to investigate the effects of concept mapping activity on science achievement and attitude. In addition, this study also aims at presenting the teaching and learning method of utilizing concept maps in order to have the students form correct concepts. The subjects were classified into two groups one group is composed of thirty-seven students (experimental group) who were participated in concept mapping activity, and the other is composed of thirty-eight students (comparison group) who were participated in the traditional teaching method. The major findings of this study are as follows: First, the concept mapping activity has a positive effect on improving students＇ science achievement. Second, the classes using concept maps have a good influence on forming students＇ science attitude. Third, the concept mapping activity is more effective in improving science achievement of mid and low level students. In conclusion, the loaming by concept mapping activity positively influence students＇ science achievement and attitude. Particularly for the students in mid and high levels, the effect is more remarkable.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.10
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• pp.60-67
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• 1990

This paper proposes a model-based fault detection method for linear/nonlinear system having modelling errors, nonlinearities and measurement noise. The system model is represented by the unified operator [5] in order to apply to both the continuous-time and discrete-time problems. The fault detection method suggested here accounts for the effects of noise, model mismatch and nonlinearities. Modelling errors are depicted by additive forms and the nominal model denominator is fixed via prior experiments in order to quantify the nucertainty bound on the parameter estima-tion. The least square method is used to estimate the numerator parameters of the nominal model. performance than traditional methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1079-1088
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• 2003

In this paper, we propose a high-resolution time-frequency domain reflectometry technique as a methodology of detection and estimation of faults on a wire. This method adopts the time-frequency cross correlation characteristics of the observed signal in both time and frequency domains simultaneously. The accuracy of the proposed method is verified with experiments using a RG type coaxial cable and comparing it with traditional time domain as well as frequency domain reflectometry methods. It is clearly shown here that the proposed algorithm produces excellent results compared to the conventional methods for single as well as multiple fault cables.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.533-542
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• 2000

Analytical experiments to determine the line-of-sight temperature distribution is conducted by using spectral radiation intensities. For this study, fourteen narrow bands of $25cm^{-1}$ interval in $CO_2\;4.3{\mu}m$ band ($2,050cm^{-1}$ to $2375cm^{-1}$) are selected. The applied system is a one-dimensional gas slab filled with 100% $CO_2$ gas at 1 atm. Two types of temperature profile are tested; parabolic and boundary layer types. Three kinds of radiation calculation are used in the iteration procedure for the temperature inversion; LBL(Line by Line), SNB(Statistical Narrow Band) and WNB(WSGGM. based Narrow Band) models. The LBL solution shows perfect agreement while some error of temperature prediction is caused by radiation modeling error when using SNB and WNB models. The inversion result shows that the WNB model may be used more accurately in spectral remote sensing techniques than the traditional SNB model.

• Korean Journal of Pharmacognosy
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• v.40 no.3
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• pp.224-228
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• 2009

For the quality control of traditional herbal medicine, Galgeun tang, simultaneous determination of glycyrrhizin, paeoniflorin, puerarin, 6-gingerol was established by using a high performance liquid chromatographic (HPLC) method with diode array detector. To separate five four constituents, DIONEX $C_{18}$ column ($5{\mu}m$, $120{\AA}$, $4.6\;mm{\times}150\;mm$) was used with gradient elution system of water and methanol. Validation of the chromatography method was evaluated by linearity, recovery, and precision test. Calibration curve of standard components showed excellent linearity ($R^2$>0.9906). Limits of detection (LOD) and limits of quantification (LOQ) varied from 0.15 to $0.52{\mu}g$/ml and 0.27 to $0.80{\mu}mg$/ml, respectively. The relative standard deviations (RSDs) of data of the intra-day and inter-day experiments were less than 2.88% and 1.21%, respectively. The results of recovery test were ranged from 96.71 to 106.29% with RSD values 0.01-0.80%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3519-3533
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• 2020

Tuberculosis is a chronic and delayed infection which is easily experienced by young people. According to the statistics of the World Health Organization (WHO), there are nearly ten million fell ill with tuberculosis and a total of 1.5 million people died from tuberculosis in 2018 (including 251000 people with HIV). Tuberculosis is the largest single infectious pathogen that leads to death. In order to help doctors with tuberculosis diagnosis, we compare the tuberculosis classification abilities of six popular convolutional neural network (CNN) models in the same data set to find the best model. Before training, we optimize three parts of CNN to achieve better results. We employ sigmoid function to replace the step function as the activation function. What's more, we use binary cross entropy function as the cost function to replace traditional quadratic cost function. Finally, we choose stochastic gradient descent (SGD) as gradient descent algorithm. From the results of our experiments, we find that Densenet121 is most suitable for tuberculosis diagnosis and achieve a highest accuracy of 0.835. The optimization and expansion depend on the increase of data set and the improvements of Densenet121.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2735-2751
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• 2020

The emergence of Software Defined Networking (SDN) overcomes the limitations of traditional networking architectures. There are some advantages in SDN which are centralized global network view, programmability, and separation of the data plane and control plane. Due to the limitation of data plane storage capacity in SDN, it is necessary to process the redundancy rules of switch. In this paper, we propose a method for active detection and processing of redundant rules. We use the result generated by the customized probe package to detect redundant rules. And by checking the forwarding behavior of probe packets in the data plane, the redundancy rules are further processed. Furthermore, in order to quickly check the dynamic networks, we propose an incremental algorithms for rapidly evolve the network strategies. We conduct simulation experiments on Matlab to verify the feasibility of the algorithm. The influence of some parameters on the result are discussed.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.937-941
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• 2006

Chitosan has a wide range of applications in biomedical materials as well as in dietary supplements. Chitosan oligosaccharide with free-amine group (COFa) is an improvement over traditional chitosan that lacks the usual impurities and materials detrimental to the body. Based on a previous study of water soluble chitosan (WSC, chitosan lactate), we investigated the molecular weight (Mw) - dependent absorption phenomena of COFa in vitro and in vivo with various Mws. The absorption of CO Fa was significantly influenced by its molecular weight. As Mw increases, the absorption decreases. The absorption profiles for 5 K COFa (Mw=5 kDa) were observed to be more than 10 times higher than those of high molecular weight chitosan (100 K HWSC Mw=100 kDa) in both in vitro and in vivo transport experiments. Furthermore, the in vitro transport experiment suggested that transcellular transport of the COFa (Mw <10 kDa) through Caco-2 cell layer could occur with a negligible cytotoxic effect. The COFas showed a cytotoxic effect on Caco-2 cells that was dependent on dose and Mw. COFa could be transported transcellularly through the Caco-2 cell layer.