• Journal of KIISE:Software and Applications
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• v.37 no.5
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• pp.341-353
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• 2010

Mobile Internet Device (MID) allows users to flexibly use various forms of wireless internet such as Wi-Fi, GSM, CDMA, and 3G. Using such Internet, MID users can utilize application services. MID usage is expected to grow due to the benefits of portability, Internet accessibility, and other convenience. However, it has resource constraints such as limited CPU power, small memory size, limited battery life, and small screen size. Consequently, MIDs are not capable to hold large-sized complex applications and to process a large amount of data in memory. An effective solution to remedy these limitations is to develop cloud services for the required application functionality, to deploy them on the server side, and to let MID users access the services through internet. A major concern on running cloud services for MIDs is the potential problems with low Quality of Service (QoS) due to the characteristics of MIDs. Even measuring the QoS of such services is more technically challenging than conventional quality measurements. In this paper, we first identify the characteristics of MIDs and cloud services for MIDs. Based on these observations, we derive a number of quality attributes and their metrics for measuring QoS of mobile services. A case study of applying the proposed quality model is presented to show its effectiveness and applicability.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.11-20
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• 2010

The distributed rainfall-runoff model which is developed in the country requires a lot of time and effort to generate input data. Also, it takes a lot of time to calculate discharge by numerical analysis based on kinematic wave theory in runoff process. Therefore, most river basins using the distributed model are of limited scale, such as small river basins. However, recently, the necessity of integrated watershed management has been increasing due to change of watershed management concept and discharge calculation of whole river basin, including upstream and downstream of dam. Thus, in this study, the feasibility of the GIS based physical distributed rainfall-runoff model, K-DRUM(K-water hydrologic & hydraulic Distributed RUnoff Model) which has been developed by own technology was reviewed in the flood discharge process for the Geum River basin, including Yongdam and Daecheong Dam Watersheds. GIS hydrological parameters were extracted from basic GIS data such as DEM, land cover and soil map, and used as input data of the model. Problems in running time and inaccuracy setting using the existing trial and error method were solved by applying an auto calibration method in setting initial soil moisture conditions. The accuracy of discharge analysis for application of the method was evaluated using VER, QER and Total Error in case of the typhoon 'Ewiniar' event. and the calculation results shows a good agreement with observed data.

• Journal of Korea Water Resources Association
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• v.50 no.3
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• pp.191-200
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• 2017

A robust parameter set (ROPS) selection framework for an unsteady flow model was developed by combining Pareto optimums obtained by outcomes of model calibration using multi-site observations with the minimax regret approach (MRA). The multi-site calibration problem which is a multi-objective problem was solved by using an aggregation approach which aggregates the weighted criteria related to different sites into one measure, and then performs a large number of individual optimization runs with different weight combinations to obtain Pareto solutions. Roughness parameter structure which can describe the variation of Manning's n with discharges and sub-reaches was proposed and the related coefficients were optimized as model parameters. By applying the MRA which is a decision criterion, the Pareto solutions were ranked based on the obtained regrets related to each Pareto solution, and the top-rated one due to the lowest aggregated regrets of both calibration and validation was determined as the only ROPS. It was found that the determination of variable roughness and the corresponding standardized RMSEs at the two gauging stations varies considerably depending on the combinations of weights on the two sites. This method can provide the robust parameter set for the multi-site calibration problems in hydrologic and hydraulic models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.188-196
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• 2021

Korea has invested heavily in projects related to national rivers, but there is no evaluation technique and system to manage river projects that can evaluate the effectiveness of the river projects after they are completed. Their absence leads to the inability of information on river construction sections, analysis of project effects, and benchmarking between projects. This may cause over-budget, overlapping investment problems due to the implementation of similar projects in the same section, and incorrect business elements may be repeatedly utilized. In order to solve this shortcoming, this study developed river project evaluation techniques and a river project (construction) management system. The development of evaluation techniques enables comparison and analysis between projects and can be utilized in establishing maintenance plans. The system can also provide inquiry of construction information, visualization of construction, and management of performance items. In this study, the evaluation techniques developed through prior research were modified and supplemented, and the effectiveness was verified by applying them to national river projects in A river and B river. It is expected that the evaluation techniques and system utilization measures presented will increase the work efficiency of river projects and enhance the efficiency of river projects.

• Journal of Korean Society of Forest Science
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• v.112 no.2
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• pp.209-216
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• 2023

This study aimed to use national forest inventory data to develop a forest productivity index and yield prediction model of a Tilia amurensis stand. The site index displaying the forest productivity of the Tilia amurensis stand was developed as a Schumacher model, and the site index classification curve was generated from the model results; its distribution growth in Korea ranged from 8-16. The growth model using age as an independent variable for breast height and height diameter estimation was derived from the Chapman-Richards and Weibull model. The Fitness Indices of the estimation models were 0.32 and 0.11, respectively, which were generally low values, but the estimation-equation residuals were evenly distributed around 0, so we judged that there would be no issue in applying the equation. The stand basal area and site index of the Tilia amurensis stand had the greatest effect on the stand-volume change. These two factors were used to derive the Tilia amurensis stand yield model, and the model's determination coefficient was approximately 94%. After verifying the residual normality of the equation and autocorrelation of the growth factors in the yield model, no particular problems were observed. Finally, the growth and yield models of the Tilia amurensis stand were used to produce the makeshift stand yield table. According to this table, when the Tilia amurensis stand is 70 years old, the estimated stand-volume per hectare would be approximately 208 m³ . It is expected that these study results will be helpful for decision-making of Tilia amurensis stands management, which have high value as a forest resource for honey and timber.

• Journal of Korea Entertainment Industry Association
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• v.6 no.4
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• pp.82-92
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• 2012

Recently people who enjoy social game via mobile devices significantly are increasing depending on the rapid adoption of smart phones and the development of the network such as LTE. Most of them are enjoying the casual gaming mobile social games that you are able to play easily, but social issues like health problems due to long play time are emerging. The users, however, do not last long because of the simplicity of the game, and there are few people who actually buy game items even though they play it long time. This study has been conducted aiming to overcome such difficulties. This study suggests ways to generate constantly revenue avoiding short-term box-office after the release of mobile social games based on the analysis for market trend and profitability of the mobile social game. In addition, by applying profitability model analyzed to Japan's most successful game practices, this paper suggests the concrete methods about the commitment of the users. For summarizing the main achievements of this paper, providing the latest market information about mobile social games, analysis of profitability, practical implications for the commitment of the users are presented.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.809-818
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• 2019

Since January 1, 2020, the International Maritime Organization (IMO) has put in place strong regulations to reduce air pollution caused by ships by lowing the upper limit of ship fuel oil sulfur content from 3.5% to 0.5% for ships passing through all sea areas around the world. Although it is important to reduce air pollutants by using fuel oil with low sulfur content, reducing the amount of energy waste through the economic operation of a ship can also help reduce air pollutants. Ships can follow designated routes accurately even under the influence of noise using autopilot systems. However, regardless of their quality, the performance of these systems is af ected by noise; heading angles with added measurement noise from the gyroscope are input into the autopilot system and degrade its performance. A technique to solve these problems reduces noise effects through the application of a Kalman filter, which is widely used in condition estimation. This method, however, cannot completely eliminate the effects of noise. Therefore, to further improve noise removal performances, in this study we propose a better denoising method than the Kalman filter technique by applying a multi-layer perceptron (MLP) in forward direction motion and a Kalman Filter in rotation motion. Simulations show that the proposed method improves forward direction motion by preventing the malfunction of a rudder more so than merely using a Kalman Filter.

• Journal of Korean society of Dental Hygiene
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• v.10 no.6
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• pp.1061-1071
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• 2010

Objectives : The purpose of this study is to train talents with high quality in dental hygienists by suggesting problems and proposing basic data available for applying to development in dental hygiene curriculum, through analyzing contents of dental hygiene curriculum. Methods : To analyze curriculum of educational institutions for dental hygienists between America and Korea, it utilized materials that were notified on each university homepage, analyzed documents, analyzed curricular content analysis, comparatively analyzed America's ASDHEP field, and comparatively analyzed Biomedical Science field, dentistry field, prevention and public field, clinical dental hygiene field, integrated curriculum, and teaching course between domestic university and American university. Results : 1. The basic field of ASDHEP was indicated the average credit in 28.6 for 4-year university with establishment and the average credit in 26.9 for 3-year university with establishment. The curricular subject field of ASDHEP except the basic field was indicated the average credit in 29.45 for 4-year university with establishment and the average credit in 30.68 for 3-year university with establishment. The prevention and public field by university was indicated the totally average credit in 27.5 for 4-year university and in 26.2 for 3-year university. The clinical dental hygiene field by university was indicated the totally average credit in 27.5 for 4-year university and in 35.0 for 3-year university. The integrated curriculum was indicated to be established dental hygiene practice(3 universities), dental clinics practice for Dept. of clinical dental hygiene(2 universities), and comprehensive dental hygiene practice(1 university) for 4-year university, and to be established clinical dental hygiene(2 universities), comprehensive dental hygiene practice, dental hygiene practice, and dental clinics practice(1 university, respectively) for 3-year university. Comparing the teaching courses by university, they were established diversely from 8 credits to 2 credits. Conclusions : Seeing the above findings, a plan for dental hygiene curriculum needs to be continuously developed so that dental hygienists can enter upon a professional career. Development in the international standard curriculum proper for global era is considered to be desperately needed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.37-42
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• 2018

With advancements in digital image production technology, the branch of stereoscopic image technology has also been undergoing active development. Accordingly, research and development on cutting-edge display products for mounting stereoscopic images are currently being pursued. There are various problems that can occur when viewing 3D images. Because viewers feel visual fatigue while perceiving the depth of the images provided via an artificial method, a negative human factor such as visual fatigue has become one of the most prominent concerns, especially as it is a factor that affects the ongoing maintenance of 3D images. Therefore, by identifying the factors affecting the depth of the graphic images provided in 2D images, and subsequently using this information to develop an image processing method, we conducted depth-related experiments and analysed them under the assumption that stereoscopic images could be reproduced without visual fatigue. Thus, we analysed the most significant factors related to depth and verified the interactions by performing depth-related factors-based ANOVA variance analysis by differentially applying the texture, colour temperature, and contrast ratio to graphic images. We determined the significance of the factors related to depth and proposed a method to improve depth based on an analysis of the results of the experiments conducted in this study.

• Composites Research
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• v.28 no.4
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• pp.168-175
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• 2015

Recently, the applications of carbon fiber reinforced plastics (CFRPs) have become broader than ever when it comes to such industries as automotive, ships, aerospace and military because of their lightweight-ness and high mechanical properties. Thermosetting plastics like epoxy are frequently used as the binding matrix in CFRPs due to their high hardness, wetting characteristics and low viscosity. However, they cannot melted and remolded. For this reason, thermosetting plastic wastes have caused serious environmental problems with the production of fiber reinforced plastics. Thus, many studies have focused on the carbon fiber reinforced thermoplastics (CFRTPs) and recycling carbon fiber. In this study, recycled carbon fiber (RCF) was prepared from CFRPs using a pyrolysis method, which was employed to separate resin and carbon fiber. The degree of decomposition for epoxy resin was confirmed from thermal gravimetric analysis (TGA) and scanning electron microscope (SEM). The RCF was cut and ground to prepare a carbon fiber composite sheet (CFCS). CFCS was manufactured by applying recycled carbon fibers and various thermoplastic fibers. Various characterizations were performed, including morphological analyses of surface and cross-section, mechanical properties, and crystallization enthalpy of CFCS at different cooling conditions.