• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.291-298
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• 2022

Recently developed drones are inexpensive and very convenient to operate. As a result, the production and utilization of spatial information using drones are increasing. However, most drones acquire images with a low-cost global navigation satellite system (GNSS) and an inertial measurement unit (IMU). Accordingly, the accuracy of the initial location and rotation angle elements of the image is low. In addition, because these drones are small and light, they can be greatly affected by wind, making it difficult to maintain a certain overlap, which degrades the positioning accuracy. Therefore, in this study, images are taken at different times in order to analyze the positioning accuracy according to changes in certain exterior orientation parameters. To do this, image processing was performed with Pix4D Mapper and the accuracy of the results was analyzed. In order to analyze the variation of the accuracy according to the exterior orientation parameters in detail, the exterior orientation parameters of the first processing result were used as meta-data for the second processing. Subsequently, the amount of change in the exterior orientation parameters was analyzed by in a strip-by-strip manner. As a result, it was proved that the changes of the Omega and Phi values among the rotation elements were related to a decrease in the height accuracy, while changes in Kappa were linked to the horizontal accuracy.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.10
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• pp.299-308
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• 2023

As the spectrum shortage problem has accelerated by the emergence of various services, New Radio-Unlicensed (NR-U) has appeared, allowing users who communicated in licensed bands to communicate in unlicensed bands. However, NR-U network users reduce the performance of Wi-Fi network users who communicate in the same unlicensed band. In this paper, we aim to simultaneously maximize the fairness and throughput of the unlicensed band, where the NR-U network users and the WiFi network users coexist. First, we propose an optimal power allocation scheme based on Monte Carlo Policy Gradient of reinforcement learning to maximize the sum of rates of NR-U networks utilizing rate-splitting multiple access in unlicensed bands. Then, we propose a channel occupancy time division algorithm based on sequential Raiffa bargaining solution of game theory that can simultaneously maximize system throughput and fairness for the coexistence of NR-U and WiFi networks in the same unlicensed band. Simulation results show that the rate splitting multiple access shows better performance than the conventional multiple access technology by comparing the sum-rate when the result value is finally converged under the same transmission power. In addition, we compare the data transfer amount and fairness of NR-U network users, WiFi network users, and total system, and prove that the channel occupancy time division algorithm based on sequential Raiffa bargaining solution of this paper satisfies throughput and fairness at the same time than other algorithms.

• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.167-180
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• 2008

The resolution of Earth images taken from a satellite has close relation with satellite's altitude. If a satellite has lower altitude, it gets a picture having better resolution. However the satellite will be exposed to heavier air drag and will spend more fuel to maintain its altitude for a desired mission. Therefore, in this study, the required fuel to maintain very low earth orbit(LEO) with severe air drag is analyzed using optimization method such as collocation method. The required fuel to maintain the low altitude has significantly increased as the mission altitude is lowered and the solar activity is maximized. This study also shows that the fuel reduced by increasing the period of the satellite maneuver is very small, and that slightly increasing the satellite's mission altitude is much effective in reducing the amount of fuel to maintain its altitude. The calculated fuel to maintain very low earth orbit in this study would give useful information in planning the budget of fuel and cost for LEO satellites.

• Cartoon and Animation Studies
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• s.15
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• pp.251-265
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• 2009

Motion Graphics are a great effective vehicle for precise communication between customers in various media and formats. The important thing in the expression of Motion Graphics is to deliver messages clearly. Some current Motion Graphics which are focused on only attracting attention or sensational expressions more than narrative are evaluated lower. This study aims to utilize easy and positive Motion Graphics to deliver messages by applying their utility to production of Motion Graphics, omitting time spent on delivering effective messages and analyzing their suggestive expression methods because of the nature of producing Motion Graphics. This thesis is to study several theoretical backgrounds of omission and implicated expressions mentioned in the similar studies from the view of Motion Graphics, and to search applied examples and functional things using the expression methods in some film title sequence. Excellent Motion Graphics use planned omission and implicated methods rather than to use entire narratives or complicated descriptions. Especially, a film title sequence should focus on symbolic visual expressions. They are necessary to attract the audience's interest. To overcome the limitation of time and space deliver a huge amount of information quickly and powerfully, Motion Graphics should properly use omission of image and time and suggestive expressions through symbols and metaphors. Then they will have a role to level up their current values and discussions.

• Journal of Internet Computing and Services
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• v.16 no.4
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• pp.1-11
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• 2015

This study uses the contingent valuation method to estimate the switching cost for adopting the MVNO service. The findings are as follows.: First, Willingness To Switch(WTS) increases as users' using pattern and perceived degree of MVNO service, but satisfaction with current service provider does not play a significant role in predicting Switching Cost. This means that as amount of money users can save exceeds a certain level, users decide to willingly change their service provider to MVNO regardless of their level of satisfaction with current service provider. Second, there are differences in WTS among service subscribers in SKT, KT and LGU+. It means that there will be a difference in the tendency to switch to MVNO among subscribers of service providers. This study suggest the following mangerial perspective to effectively promote the MVNO and boost the MVNO market for activation of mobile data services.: First, MVNOs are better off applying differentiated pricing scheme at attractive rates than using a differentiation of service product and quality. Second, regulators should consider how to implement an MVNO regulatory policy when there is an asymmetric customer loyalty among MNOs. This research will be used to set the MVNO's pricing strategy and to build up a successful regulatory policies.

• Journal of Internet Computing and Services
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• v.11 no.6
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• pp.13-20
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• 2010

This paper presents a measure to classify healthy persons and Parkinson disease patients from the foot pressure of healthy persons and that of Parkinson disease patients using gait analysis based characteristics extraction and Neural Network with Weighted Fuzzy Membership Functions (NEWFM). To extract the inputs to be used in NEWFM, in the first step, the foot pressure data provided by the PhysioBank and changes in foot pressure over time were used to extract four characteristics respectively. In the second step, wavelet coefficients were extracted from the eight characteristics extracted from the previous stage using the wavelet transform (WT). In the final step, 40 inputs were extracted from the extracted wavelet coefficients using statistical methods including the frequency distribution of signals and the amount of variability in the frequency distribution. NEWFM showed high accuracy in the case of the characteristics obtained using differences between the left foot pressure and the right food pressure and in the case of the characteristics obtained using differences in changes in foot pressure over time when healthy persons and Parkinson disease patients were classified by extracting eight characteristics from foot pressure data. Based on these results, the fact that differences between the left and right foot pressures of Parkinson disease patients who show a characteristic of dragging their feet in gaits were relatively smaller than those of healthy persons could be identified through this experiment.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1247-1255
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• 2013

In this paper, We proposes multipurpose function electronic measurement reference station prototype system based on LED and Gyro Sensor. This system have developed to possible with real time data collection and landscape illumination and surrounding diastrophism monitoring for that analyze problems of existing planted reference station. Hardware for the proposed system consists of a gyro sensor module to detect diastrophism, GPS module to process location information, environment sensor module to process surrounding environmental data and CDMA wireless data communication to send the collected data to server. In addition, this paper intends to enhance system management and future usability in a way that applies LED, QR-code, RFID and Solar cell module to outer side of electronic measurement reference station to improve usability of H/W for electronic measurement reference station. Lastly, this paper conducted current amount evaluation to supply stabilized electricity with its various functions in the proposed multipurpose function electronic measurement reference station and it's proved that this system can be stably operated with its electricity loss factor of 2.29% loss factor. And this paper conducted a qualitative comparison with existing electronic measurement reference station system in order to evaluate superiority of the proposed electronic measurement reference station.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.532-541
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• 2017

Design is an extremely critical and important for the prosperity and development of a corporation, and design for children's facilities can be said to be a critical factor not only from a commercial perspective but also one of the critical factors that can be beneficial to the physical, intellectual and emotional growth and development of children. To measure the economic value of publicly designed children's facilities established with the purpose of children's design education, this research study utilized the Contingent Valuation Method. This research study attempts to provide useful information for policy administrators on the usage of both publicly designed children's facilities with high use value and also high non-use value through economic value measurement. To achieve the objectives of this research, the Contingent Valuation Method that utilized both open-ended questions and also double-bounded dichotomous choice methodologies was used. The results of the pre-verification that used the open-ended questions results from 50 test subject participants and the double-bounded dichotomous choice methodology results from 530 test subject participants confirmed that the average annual per person expense was estimated to be KRW 12,463. The gross benefit amount figure estimated for all households in the nation was estimated to be about KRW 219 billion annually.

• The KIPS Transactions:PartD
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• v.11D no.5
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• pp.1123-1132
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• 2004

Successful project planning relies on a good estimation of the manpower required to complete a project. The good estimation can be derived from Rutnam's Rayleigh Model or Phillai et al.'s Gamma Model. These models only can be applied for the projects which the need of manpower is increased exponentially and the highest of manpower is required at the end of development phase. However, in a practical project, most manpower is required during development phase and a small amount of manpower is assigned during maintenance phase. In addition, the Waterfall Model and Unified Process only can be adopted for development phase. So the current development environments cannot be adopted into the existing manpower distribution models which the highest manpower is required at the end of development phase. This paper suggests an appropriate model for development phase to solve this problem. First, the appropriate manpower distribution for development phase of the Waterfall model was derived from Putnam's manpower distribution and then manpower distribution of development phase was derived for Unified Process. After comparing the required manpower of two Processes, total manpower distribution is similar each other even though the required manpower and task is different for each point of development phase. From this result, a unified model is derived and it can be applied for both development processes.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.135-146
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• 2005

Up to now studies on the fusion of travel time from various detectors have been conducted based on the variance raito of the intermittent data mainly collected by GPS or probe vehicles. The fusion model based on the variance ratio of intermittent data is not suitable for the license plate recognition AVIs which can deal with vast amount of data. This study was carried out to develop the fusion model based on travel time acquired from the license plate recognition AVIs and the point detectors. In order to fuse travel time acquired from the point detectors and the license plate recognition AVIs, the optimized fusion model and the proportional fusion model were developed in this study. As a result of verification, the optimized fusion model showed the superior estimation performance. The optimized fusion model is the dynamic fusion ratio estimation model on real time base, which calculates fusion weights based on real time historic data and applies them to the current time period. The results of this study are expected to be used effectively for National Highway Traffic Management System to provide traffic information in the future. However, there should be further studies on the Proper distance for the establishment of the AVIs and the license plate matching rate according to the lanes for AVIs to be established.