• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.183-191
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• 2021

Non-intrusive load monitoring is a technology that can be used for predicting and classifying the type of appliances through real-time monitoring of user power consumption, and it has recently got interested as a means of energy-saving. In this paper, we propose a system for classifying appliances from user consumption data by combining GAF(Gramian angular field) technique that can be used for converting one-dimensional data to the two-dimensional matrix with convolutional neural networks. We use REDD(residential energy disaggregation dataset) that is the public appliances power data and confirm the classification accuracy of the GASF(Gramian angular summation field) and GADF(Gramian angular difference field). Simulation results show that both models showed 94% accuracy on appliances with binary-state(on/off) and that GASF showed 93.5% accuracy that is 3% higher than GADF on appliances with multi-state. In later studies, we plan to increase the dataset and optimize the model to improve accuracy and speed.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.45-55
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• 2021

In this study, the behavioral characteristics of the fill dam were analyzed during water level fluctuations through a numerical analysis model, and the reservoir safety management plan was prepared. The variation in plastic deviatoric strain, horizontal displacement, stress path, pore water pressure, etc., due to elevation of water level in the upper and lower sides of shell and core were analyzed using numerical analysis software, viz. GTS NX and LIQCA. The analysis results manifest that as the water level in the dam body increases rapidly, the pore water pressure and displacement also increase quickly. It was found that the elevation of the water level causes an increase in pore water pressure in the dam body as well as an increase in the saturation of the dam body and decreased effective stress. It is considered that this type of dam behavior can be the cause of the reduction of strength and stiffness of the dam. Also, it is assumed that the accumulated plastic deviatoric strain due to the deformation of the dam body caused by water infiltration causes an increase in displacement. Based on these experimental results and the results of analyses of the existing reservoir safety diagnosis techniques, an improvement plan for dam safety diagnosis and evaluation criteria was proposed, and these results can be used as primary data while revising dam safety diagnosis guidelines.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.119-125
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• 2020

Research on high-attenuation concrete for the vibration reduction performance by mixing epoxy-based synthetic resins and aggregates is actively being conducted. The curing time of high-attenuation concrete is very short because water is not used, and the physical and dynamic properties are very excellent. therefore, it is expected to be widely used in building structures requiring reduction of interior-floor noise and vibration. Furthermore, A way to expand the applicability of the high-damping concrete mixed with polymer in the field of reinforcement material have been variously studied. In order to replace polymer concrete with ordirnary concrete and existing anti-vibration reinforcement material, it is necessary to review overall vibration reduction performance considering physical properties, dynamic properties, productivity and field applicability. In this study, the physical and dynamic properties of polymer concrete by epoxy mixing ratio compared with ordirnary concrete. As a result, the elastic modulus was similar. On the other hand, polymer concrete for the compressive, tensile, and flexural strengths was quite more excellent. In particular, the measured tensile strength of polymer concrete was 4-10 times higher than that of ordirnary concrete. it was a big difference, and the frequency response function and damping ratio was studied through modal test and finite element analysis model. The dynamic stiffness of polymer concrete was 20% greater than that of ordirnary concrete, and the damping ratio of polymer concrete was approximately 3 times more than that of ordirnary concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.520-530
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• 2021

Objectives: This study aimed to identify the effects of music therapy on cognitive function, agitation, anxiety and depression in the elderly with dementia. Method: A comprehensive literature search was performed on PubMed, EMBASE, Cochrane Library, CINAHL, Web of Science, Google scholar and PsycINFO, for the period 2010 to 2019. In the meta-analysis, the standardized mean difference (Hedges' g) and 95% confidence interval were calculated as summary measure, and the random effect model and inverse variance method were applied using the RevMan 5.4 program. A total of 13 studies were included; all were determined to be acceptable, based on the Cochrane collaboration's tool for assessing risk of bias. Results: The effect size (Hedges' g) was 0.31 (95% CI: -0.02, 0.65) for cognition and -0.03 (95% CI: -0.17, 0.11) for agitation behavior as the primary outcomes, and 0.61 (95% CI: -1.17, -0.05) for anxiety and -0.44(95% CI: -0.88, 0.00) for depression as the secondary outcomes. Subgroup analysis by type of music intervention revealed that combined music therapy has a significantly increasing beneficial effect on cognition of dementia patients (g=0.45[95% CI: 0.03, 0.87]). Conclusion: Music therapy was determined to exert beneficial effects in reducing anxiety and depression, and combined music therapy demonstrated improved cognitive functions in elderly patients with dementia.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.75-84
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• 2020

This paper described the analysis result on heaving of soft ground with DCM column type, based on the results of laboratory model tests on the soft ground with DCM column. The heave characteristics of the soft ground were evaluated according to the application of DCM column in soft ground. The results showed that the heaving of soft ground without DCM column occurred rapidly when the lateral deformation of soft ground increased significantly under the 4th load step condition. In addition, the heaving of soft ground in final load step caused tensile failure of the ground surface. The maximum heaving of the soft ground with the DCM column occurred in the final load step, and the heaving quantity decreased in the order of pile, wall, and grid type. Especially, the soft ground with DCM of grid type effectively resisted ground heaving, even if it was extremely failure in the bottom ground of embankment. The results of the maximum heaving according to the measurement point showed that the heaving of the soft ground with DCM of grid type was 3.1% and 1.6% compared to that of the pile and wall type at the location of LVDT-1, and the heaving of the LVDT-2 position was 1.0% and 2.1%, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.573-581
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• 2020

Using CCTV images and weather parameters, a method for estimating PM (Particulate Matter) index was proposed, and an experiment was conducted. For CCTV images, we proposed a method of estimating the PM index by applying a deep learning technique based on a CNN (Convolutional Neural Network) with ROI(Region Of Interest) image including a specific spot and an full area image. In addition, after combining the predicted result values by deep learning with the two weather parameters of humidity and wind speed, a post-processing experiment was also conducted to calculate the modified PM index using the learned regression model. As a result of the experiment, the estimated value of the PM index from the CCTV image was R2(R-Squared) 0.58~0.89, and the result of learning the ROI image and the full area image with the measuring device was the best. The result of post-processing using weather parameters did not always show improvement in accuracy in all cases in the experimental area.

• The Journal of the Korea Contents Association
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• v.20 no.12
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• pp.346-356
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• 2020

Purpose: This study was to identify the Health beliefs of the vulnerable group on the prevention of STI and to identify the factors that influence prevention behavior. Methods: The participants were 241 of persons vulnerable to STI. A total of 241 questionnaires were collected by mail or in person through relevant workplace, group members, and visitors to public health centers with structured questionnaires. The SPSS 21.0 program was used to perform descriptive statistics, t-test, one way ANOVA, Pearson's correlation and multiple regression. Results: As a result, the level of perceived susceptibility was 2.70, perceived severity was 3.63, perceived benefits of condom use was 3.82, Perceived barriers of condom use was 2.45, self-efficacy of condom use 3.93 and prevention behavior of STI was 3.51 based on 5-point Likert scale. Condom use self-efficacy(��=.23, p=.003), perceived barriers of condom use(��=-.15, p=.035), and level of education(��=.16, p=.018) were important factors influencing STI prevention behavior and the regression model explained 17% of STI prevention. In conclusion, it is necessary to develop a systematic education program in consideration of factors influencing and improving awareness to prevent STI.

• Knowledge Management Research
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• v.22 no.1
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• pp.243-267
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• 2021

Sentiment represents one's own state through the process of change to stimulus, and emotion represents a simple psychological state felt for a certain phenomenon. These two terms tend to be used interchangeably, but their meaning and usage are different. In this study, we try to find out how it affects the helpfulness of reviews by classifying sentiment and emotion through online reviews written by online consumers after purchasing and using various products and services. Recently, online reviews have become a very important factor for businesses and consumers. Helpful reviews play a key role in the decision-making process of potential customers and can be assessed through review helpfulness. The helpfulness of reviews is becoming increasingly important in practice as it is utilized in marketing strategies in business as well as in purchasing decision-making issues of consumers. And academically, the importance of research to find the factors influencing the helpfulness of reviews is growing. In this study, Yelp.com secured reviews on restaurants and conducted a study on how the sentiment and emotion of online reviews affect the helpfulness of reviews. Based on the prior research, a research model including sentiment and emotions for online reviews was built, and text mining analyzes how the sentiment and emotion of online reviews affect the helpfulness of online reviews, and the difference in the effects on emotions It was verified. The results showed that negative sentiment and emotion had a greater effect on review helpfulness, which was consistent with the negative bias theory.

• The Journal of the Korea Contents Association
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• v.21 no.3
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• pp.720-729
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• 2021

The purpose of this study was to measure repeated the process of non-suicidal self-injury individuals change in everyday life through the Ecological Momentary Assessment(EMA) daily diary. The study subjects of were 17 adults aged 19 to 29, accessed a link sent by text message on a cell phone and recorded a diary of the day's affects, interpersonal conflicts, self-injury thoughts, and behaviors once a day for two weeks. Using a total of 238 reported entries, the contextual factors of NSSI were examined, and the effects of affects and interpersonal conflicts on NSSI analyzed through a multi-level model. As a result, the negative affects of that day have a significant relation with within subject NSSI behavior and positive affects have a significant relation between subject NSSI behavior. These findings means that overall individuals with low positive affects have a higher risk of self-injury behavior compared to those with higher levles of positive emotions, and an increase in negative emotions on that day within an individual increases the risk of self-injury behavior on that day. In other words, it implies that it is important to manage negative emotions and strengthen overall positive affects for that day in the intervention of emotion-regulation of experienced self-injury individuals. It is meaningful that this study explored NSSI risk factors experienced in daily life through the short-term longitudinal study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.1-12
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• 2021

Technologies for an MVDC(medium voltage direct current) distribution system are being considered as an effective alternative to overcome the interconnection delay issues of PV systems. However, the implementation of a DC distribution system might lead to economic problems because of the development of DC devices. Therefore, this paper deals with the scale of a PV plant based on its capacity and proposes hosting-capacity models for PV systems to establish a network to evaluate the feasibility of an MVDC distribution system. The proposed models can be classified as AC and DC distribution systems by the power-supply method. PV systems with hundreds of MW, dozens of MW, and a few MW can be categorized as large-scale, medium-scale, and small-scale models, respectively. This paper also performed modeling for an economic evaluation of MVDC distribution system by considering both the cost of AC and DC network construction, converter replacement, operation, etc. The profit was composed of the SMP and REC rate of a PV plant. A simulation for economic evaluation was done for the MVDC distribution system using the present worth and equal-principal costs repayment method. The results confirmed that the proposed model is a useful tool to evaluate economic issues of a DC distribution system.