• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1216-1223
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• 2018

As field of application of AMI, AMR uses the power line as the primary means of communication. PLC has a big merit without installation of the new network for communication in a field using the power line which is the existing equipment. However, there is a serious obstacle in commercialization for the instability by noise and communication environment. Therefore, the technical method for maintaining the communication state which overcome such demerit and was stabilized is required essentially. PLC routing technology is applied with the alternative plan now. The routing technology currently managed by field includes many problems by applying the algorithm of an elementary level. PLC routing path search problem can be modeled with the problem of searching for optimal solution as similar to such as optimal routing problem and TSP(Travelling salesman problem). In this paper, in order to search for a PLC routing path efficiently and to choose the optimal path, GA(Genetic Algorithm) was applied. Although PLC was similar in optimal solution search as compared with typical GA, it also has a difference point by the characteristic of communication, and presented the new methodology over this. Moreover, the validity of application technology was verified by showing the experimental result to which GA is applied and analyzing as compared with the existing algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1926-1938
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• 2009

In this study, detection system of the blood flow variation rate was implemented using the variation effect of bio electric impedance at time of the blood pressure measurement by means of impedance method. The blood pressure measurement was performed by the oscillometric method. The mean arterial pressure was calculated using maximum amplitude algorithm. The systolic and diastolic pressure were estimated by establishment of the various characteristic ratio according to mean arterial pressure range. Alternative static current source and lock_in amplifier were introduced to impedance measurement. The variation of blood volume was measured using variation bio impedance according to induced cuff pressure at measuring area.

• Journal of Information Technology Services
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• v.9 no.2
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• pp.43-72
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• 2010

The Korean mobile telecommunication service market is faced with a tremendous competitive period, in which the market is entering into the maturity stage with launching of the 3rd generation service and with introduction of mobile number portability. In general, it is more important to sustain the old customers than to attracting new customers, as the life cycle of an industry is entering the maturity stage in which the growth rate of new customers is decreasing gradually or becoming stagnant. Until now, many researches had tested whether the customer satisfaction and loyalty were the core factors of sustaining customers or not. Also service quality and switching cost were given a remarkable attention for their possibility of exogenous factors, which could exercise effects to customer satisfaction and loyalty. In the same context, mobile telecommunication business has to seek a way to maintain the existing customers instead of promoting new customers. So this study investigates whether the service quality and switching barrier of mobile telecommunication could have effects on the customer satisfaction and loyalty, which are recognized as an efficient means to sustain the current customers. In order to test the hypothesis on the effects of service quality and switching barrier of mobile telecommunication to customer satisfaction and loyalty in Korean telecommunication industry, this study collected the questionnaire response data of students including middle and high school students and undergraduates, who are regarded as the major customers in that mobile telecommunication industry.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.96-103
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• 2012

In this study, we used HARVEST, a timber management strategy assessment tool, to evaluate alternative forest planning strategies on spatial pattern of cutting blocks. We applied the tool to the Gwangreung Experimental Forest (GEF) as a case study. The harvest schedules developed for GEF using a linear programming model was used to assess spatial patterns of cutting blocks under different management constraints. The results show that the allowable maximum harvest size largely affects the number, size, and distribution of cutting blocks. We also found that spatial dispersion methods and adjacency constraints could be used as an effective means to control spatial allocation of cutting blocks in order to meet certain forest ecosystem management goals.

• Journal of radiological science and technology
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• v.3 no.1
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• pp.57-66
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• 1980

X-ray grid is the most important means to reduce the scattered ray from patients, but alternative way is air gap technique that is another name of Groedel technique. This technique is mainly used in chest radiography. Authors performed an experimental study on the air gap technique for chest radiography and obtained the results as follows; 1. In using the high voltage air technique, scattered ray could be reduced effectively, while the percentage of scattered ray was slightly increased than conventional grid technique. 2. In film contrast, 30cm air gap technique was inferior to 12:1 grid technique and contrast improvement was increased when the object was thicker and higher voltage was used. 3. The patient exposure dose was reduced about $25{\sim}45%$ compared with conventional grid technique by air gap technique used.

• The Korean Journal of Applied Statistics
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• v.11 no.2
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• pp.435-449
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• 1998

In this article we have introduced a Bayes criterion for the variable selection in multiple discriminant analysis (MDA). The criterion is a default Bayes factor for the comparision of homo/heteroscadasticity of the multivariate normal means. The default Bayes factor is obtained from a development of the imaginary training sample method introduced by Spiegelhalter and Smith (1982). Based an the criterion, we also provided a test for additional discrimination in MDA. The advantage of the criterion is that it is not only applicable for the optimal subset selection method but for the stepwise method. More over, the criterion can be reduced to that for two-group discriminant analysis. Thus the criterion can be regarded as an unified alternative to variable selection criteria suggested by various sampling theory approaches. To illustrate the performance of the criterion, a numerical study has bean done via Monte Carlo experiment.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.7-14
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• 2003

Statistics shows that 80% of freeway users travel less than 50km, and only 8% of them do over 100km. It means that the freeway is used for commuting. As a result, the freeway is not used efficiently and social cost is high. The current toll system aims for the efficient usage of the freeway by restraining short-distance trips and inducing long-distance ones. Thus, policies such as minimum toll system and discount for long-distance trips have been carried out. However. these two policies take no account of demand management between the freeway and alternative roads. They merely consider the compensation for charge on users, so the assessment of discount rate and distinction of distance are not reasonable. Consequently, not only the effective demand management but also the evaluation of those policies has been difficult to be achieved. The objective of this paper is to analyze those problematic policies and to establish a reasonable and improved toll system. In addition, this study presents the methodology to minimize social cost, which can be achieved by reducing short trips and encouraging long ones on the freeway. A new methodology of freeway toll system is applied and the results are presented.

• Structural Engineering and Mechanics
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• v.73 no.5
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• pp.487-500
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• 2020

Stiffeners can be utilised to enhance the strength of thin-walled wind turbine towers in engineering practise, thus, structural performance of wind turbine towers by means of different stiffening schemes should be compared to explore the optimal structural enhancement method. In this paper two alternative stiffening methods, employing horizontal or vertical stiffeners, for steel tubular wind turbine towers have been studied. In particular, two groups of three wind turbine towers of 50m, 150m and 250m in height, stiffened by horizontal rings and vertical strips respectively, were analysed by using FEM software of ABAQUS. For each height level tower, the mass of the stiffening rings is equal to that of vertical stiffeners each other. The maximum von Mises stresses and horizontal sways of these towers with vertical stiffeners is compared with the corresponding ring-stiffened towers. A linear buckling analysis is conducted to study the buckling modes and critical buckling loads of the three height levels of tower. The buckling modes and eigenvalues of the 50m, 150m and 250m vertically stiffened towers were also compared with those of the horizontally stiffened towers. The numbers and central angles of the vertical stiffeners are considered as design variables to study the effect of vertical stiffeners on the structural performance of wind turbine towers. Following an extensive parametric study, these strengthening techniques were compared with each other and it is obtained that the use of vertical stiffeners is a more efficient approach to enhance the stability and strength of intermediate and high towers than the use of horizontal rings.

• International Journal of Stem Cells
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• v.7 no.2
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• pp.108-117
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• 2014

Background and Objectives: Genomic imprinting is an inheritance phenomenon by which a subset of genes are expressed from one allele of two homologous chromosomes in a parent of origin-specific manner. Even though fine-tuned regulation of genomic imprinting process is essential for normal development, no other means are available to study genomic imprinting in human during embryonic development. In relation with this bottleneck, differentiation of human embryonic stem cells (hESCs) into specialized lineages may be considered as an alternative to mimic human development. Methods and Results: In this study, hESCs were differentiated into three lineage cell types to analyze temporal and spatial expression of imprinted genes. Of 19 imprinted genes examined, 15 imprinted genes showed similar transcriptional level among two hESC lines and two human induced pluripotent stem cell (hiPSC) lines. Expressional patterns of most imprinted genes were varied in progenitors and fully differentiated cells which were derived from hESCs. Also, no consistence was observed in the expression pattern of imprinted genes within an imprinting domain during in vitro differentiation of hESCs into three lineage cell types. Conclusions: Transcriptional expression of imprinted genes is regulated in a cell type- specific manner in hESCs during in vitro differentiation.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2394-2402
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• 2018

Textile dyes are some of the pollutants which have received the most attention because of the large volume of wastewater generated by the textile industry. Removal by means of adsorption is one of the most versatile alternatives to treat these effluents. Even though different adsorbents such as activated carbons and mineral materials have been proposed, polymeric adsorbents are a viable alternative. This work reports for the first time the use of polyelectrolyte PTZ and macroelectrolyte MTZ containing tetrazole groups as adsorbents useful in the textile dyes removal present in aqueous solutions and wastewater. Because of the anionic character of the tetrazole group, MTZ exhibits selective adsorption capabilities for cationic dyes of up to $156.25mg{\cdot}g^{-1}$. The kinetic study of the process of adsorption shows that PTZ and MTZ fit a pseudo second-order model. MTZ also shows utility as a flocculant agent in the treatment of wastewater containing dyes Indigo Blue and Reactive Black. The results showed that PTZ and MTZ may be used in the treatment of wastewater in a process of coagulation-flocculation followed by the treatment by adsorption. This two-stage treatment removed up to 95% of the dye present in the wastewater. As well as removing the dyes, the values for COD, suspended solids, pH, and color of the wastewater decreased, thus significantly improving its quality.