• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.12
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• pp.689-697
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• 2005

In this paper, an application of a decentralized $H_{\infty}$ controller(DHC) to multiple controlled-permanent magnet(CMAG) magnetic levitation(Maglev) systems is presented. The designed DHC using two Riccati equations iteratively has simpler structure and needs less computational loads than conventional centralized $H_{\infty}$ controller. A target plant is a hybrid-type CMAG system with permanent magnet and coil, and its mathematical model is firstly derived to design the DHC. To implement the designed algorithm, a real Maglev vehicle system including digital controller, chopper, sensor, etc., is manufactured. To compare the performances of the DHC method with an observer-based state feedback control(OSFC), the input tracking and disturbance rejection characteristics are experimentally tested. As performance indices(PI), integral of squared error(ISE), integral of absolute error(IAE), integral of time multiplied by absolute error(ITAE) and integral of time multiplied by squared error(ITSE) are used. From the experimental results, it can be seen that the input tracking and disturbance rejection performances of the DHC are better than those of the conventional controller.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.1-8
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• 2021

A series of pot experiments were conducted to quantitatively estimate inhibitory effects of reclaimed soil on the growth of Lentil (Lens culinaris) with two soils remediated by land farming (DDC) and low temperature thermal desorption(YJ), respectively. After cultivation in a growth chamber for 8 days, plants were harvested for the analysis of 8 indices including chlorophyll-a and carotenoid in leaves, shoot fresh weight, root dry weight, root length, number of later roots, specific root length (SRL) as well as germination rate in comparison to control experiment conducted on nursery soil. Root length was estimated by SmartRoot program from the digital images of the roots. The results showed germination rate on YJ and DDC soil decreased 29 and 71%, respectively. In comparison to the control, the averaged value of the 8 indices for YJ and DDC soil showed overall growth inhibition was 48 and 68%, respectively. When the same experiment was conducted with 25% (W/W) vermiculate amended soil, plant growth on each soil was comparable to that of the control. The results implies reclaimed soils requires additional processes and/or amendments to reuse for plant growth.

• Journal of Information Technology Services
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• v.22 no.2
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• pp.71-92
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• 2023

Globally, under the leadership of advanced ICT countries, the private sector is promoting various policies to promote the digital transformation of public services. Looking at the research trend, design of public service indicators, development of evaluation system, and empirical research are being carried out steadily, but there are insufficient research cases on models in which the private sector participates in the planning, development, and operation of public services. In this study, Private-centric digital public service suitability evaluation indicators were discovered through interviews with experts in various fields, and weights for each indicator were analyzed through AHP evaluation. In addition, by applying the analysis results to 18 digital public services on a trial basis, the importance and priority of evaluation indicators for each service were derived, and at the same time, the evaluation framework was designed and applied to diagnose implications. As a result of the study, 'social utility', 'corporate acceptability', and 'public acceptability' were selected as the top three indicators of suitability evaluation. At this time, it was analyzed that the weight of the 'company acceptability' index, which includes sub-indices such as 'service profitability', 'service scalability', and 'private initiative possibility', was the highest among the three top indicators. As a result of the demonstration for public services, "IoT facility unmanned remote monitoring service", "blockchain real estate transaction service", and "digital twin disaster prediction service" were evaluated as the most suitable public services for the transition to the private sector.

• Journal of the Korean Society for information Management
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• v.20 no.3
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• pp.31-49
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• 2003

Electronic publications, including e-journals, show a rapid expansion due to its several advantages for the academic and research community. The purpose of this study is to analyze the impact of e-journals on scholarly communication. The impact factors and immediacy indices were provided via JCR social science edition have been used to conduct a series of analysis on three subject fields, economics, law and psychology. The data from the last eight years show that the impact factors of e-journals have not changed, but immediacy indices have intensely increased in recent two years. Significant increase of immediacy indices is probably due to prevalence of e-journals or electronic sources of articles. The result reveals that e-journals play an important role in speeding up the scholarly communication. It is expected that the findings of this study can contribute to more efficient management of the digital libraries.

• Journal of Korean Society of Rural Planning
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• v.7 no.1 s.13
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• pp.37-48
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• 2001

The purpose of this study is to suggest the landscape potential index for visualizing landscape information in the conservation of hilly landscape in urban fringe. For the visual and quantitative approach to topological landscape assessment, numerical entity data of DEM(digital elevation model) were processed with CAD-based utilities that we developed and were mainly focused on analysis of visibility and visual sensitivity. Some results, with reference in assessing greenbelt area of Eodeung Mt. in Gwangju, proved to be considerable in the landscape assessment of suburban hilly landscapes. 1) Since the viewpoints and viewpoint fields were critical to landscape structure, randomized 194 points(spatially 500m interval) were applied to assessing the generalized visual sensitivity, we called. Because there were similar patterns of distribution comparing to those by 56 points and 18 Points given appropriately, it could be more efficient by a few viewpoints which located widely. 2) Regressional function was derived to represent the relationships between probabilities of visibility frequency and the topological factors(topological dominance, landform complexity and relational aspect) of target field. 3) Visibility scores of each viewpoint were be calculated by summing the visual sensitivity indices within a scene. The scores to the upper part including ridge line have been more representative to overall distributions of visual sensitivities. Also, with sum of deviations of sensitivity indices from each single point's specific index to the weighting values of view points could be estimated rotationally. 4) The deviational distributions of visual sensitivity classes in the topological unit of target field were proved to represent the visual vulnerability of the landform. 5) Landscape potential indices combined with the visual sensitivity and the DGN(degree of green naturality) were proposed as visualized landscape information distributed by topological unit.

• Physical Therapy Korea
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• v.26 no.1
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• pp.28-36
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• 2019

Background: Temporomandibular disorder (TMD) is characterized by pain and limited range of motion in the jaw. TMD patients generally prefer to chew on the unaffected or less-affected side, and this tendency often results in asymmetries in masseter muscle thickness and range of mandibular motion. Objects: The purpose of this study was to compare the asymmetries in masseter muscle thickness and range of mandibular motion in subjects with and without temporomandibular disorders. Methods: Thirty-nine subjects were divided into two groups: A TMD group ($n_1=19$) and a control group ($n_2=20$). The jaw opening range and laterotrusion were measured using a digital vernier caliper. The masseter muscle thickness was examined in both the resting state and the maximal clenching state using ultrasonography. The absolute asymmetry indices calculated based on the laterotrusion and masseter muscle thickness of the respective right and left sides. A two-way ANOVA and a Mann-Whitney U test were used for statistical analysis. Results: No significant different was found in the masseter muscle thickness between the TMD and control group. A significant difference was found in the absolute asymmetry indices of mandibular laterotrusion between the TMD and control groups (p<.05). Furthermore, the ranges of jaw opening were significantly different between males and females (p<.05). The absolute asymmetry index values of masseter muscle thickness at rest and during maximal clenching were also significantly different between males and females (p<.05). Conclusion: These results demonstrated that the subjects with TMD had a larger degree of asymmetry in laterotrusion than those without TMD. Therefore, a physiotherapy program needs to be designed to restore normal laterotrusion capacities for TMD subjects. These results also showed that female subjects had greater absolute asymmetry indices in masseter muscle thickness than male subjects. Therefore, more training is needed to promote bilaterally balanced chewing among women.

• The Journal of the Korea Contents Association
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• v.11 no.11
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• pp.79-90
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• 2011

The purpose of this study is to explore physical factor of digital text structure for designing e-Book interface and to develop prototype of e-Book interface by applied these factors. To address this goal, explore factor analysis and confirmatory factor analysis were employed, 237 university students were the participated in this study. According to a result, 29 items for physical feature of digital text structure were developed, 9 factors of digital text structure were also extracted; volume, depth, density, space, layout, format, signal, size, and length. Besides, to identify structure of pre-defined 9 factors, confirmatory factor analysis was conducted. As a result of CFA, the factor structure was supported by all of model fit indices.

• Journal of the Korea Society of Computer and Information
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• v.28 no.9
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• pp.177-188
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• 2023

The purpose of this study is to develop and validate a scale for measuring digital literacy by identifying the factors consisting of digital literacy and extracting items for each factor. Preliminary items for the Delphi study were developed through the analysis of previous literature and the deliberation of the research team. As a result of two rounds of the expert Delphi study, 65 items were selected for the main survey. The validation of the items was carried out in the process of exploratory and confirmatory factor analyses, reliability test, and criterion validity test using the data collected in the main survey. As a result, a 4-factor structure composed of 31 questions(factor 1: digital technology & data literacy- 9 questions, factor 2: digital content & media literacy- 8 questions, factor 3: digital communication & community literacy- 9 questions, factor 4: digital wellness literacy - 5 questions) was confirmed. Also, the goodness of fit indices of the model were found to be good and the result of reliability test revealed the scale had a very appropriate level of Cronbach's alpha(α=.956). In addition, a statistically significantly positive correlations(p<.001) were found between digital literacy and internet self-efficacy and between digital literacy and self-directed learning ability, which were predicted in the existing evidence, therefore the criterion validity of the developed scale was secured. Finally, practical and academic implications of the study are provided and future study and limitations of the study are discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1180-1188
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• 2015

In this paper, we propose a new subband quantizer which is a type of quad-tree for applying to digital hologram compression based on Fresenelet transform. After executing Fresnelet transform to the captured digital holgoram, we analyze effect of the designed quantizer for the reconstructed objects from analyzing average energy of each coefficient and visual importance in all subbands. We analyze distribution of coefficient and set dynamic range for each subband, and then design subband quantizer. For enhancing effectiveness of the designed quantize, we adopt a method using the coefficients which are located out of dynamic range, which are named by exception indices. From this, we can obtain more effective quantizer which has higher performance in a range of σ′ = 5.0.

• Journal of Ecology and Environment
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• v.41 no.2
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• pp.34-44
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• 2017

Background: Monitoring terrestrial vegetation cover condition is important to evaluate its current condition and to identify potential vulnerabilities. Due to simplicity and low cost, point intercept method has been widely used in evaluating grassland surface and quantifying cover conditions. Field-based digital photography method is gaining popularity for the purpose of cover estimate, as it can reduce field time and enable additional analysis in the future. However, the caveats and uncertainty among field-based vegetation cover estimation methods is not well known, especially across a wide range of cover conditions. We compared cover estimates from point intercept and digital photography methods with varying sampling intensities (25, 49, and 100 points within an image), across 61 transects in typical steppe, forest steppe, and desert steppe in central Mongolia. We classified three photosynthetic groups of cover important to grassland ecosystem functioning: photosynthetic vegetation, non-photosynthetic vegetation, and bare soil. We also acquired normalized difference vegetation index from satellite image comparison with the field-based cover. Results: Photosynthetic vegetation estimates by point intercept method were correlated with normalized difference vegetation index, with improvement when non-photosynthetic vegetation was combined. For digital photography method, photosynthetic and non-photosynthetic vegetation estimates showed no correlation with normalized difference vegetation index, but combining of both showed moderate and significant correlation, which slightly increased with greater sampling intensity. Conclusions: Results imply that varying greenness is playing an important role in classification accuracy confusion. We suggest adopting measures to reduce observer bias and better distinguishing greenness levels in combination with multispectral indices to improve estimates on dry matter.