• Journal of Digital Convergence
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• v.15 no.7
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• pp.27-39
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• 2017

To grasp the current status of smart campus and look for future directions, this study investigated the usage rate and perceived usefulness of digital devices and services by conducting online survey of 580 university students. The main results are as follows. First, smartphones have the highest ownership rate, followed by laptops, desktops, and digital cameras. Purchase intention of virtual reality devices is highest followed by smart watches/bands, and tablets. Second, mobilization in campus life is almost realized, however the usage of desktops is still high in education and administration context. Digital devices have been perceived particularly useful when searching and sharing information. Third, students use digital services such as search engines, messengers, and online libraries in their learning, and they use messengers, music and video services in their lives. Service usage rate and perceived usefulness are not proportional.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.237-242
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• 2020

Online e-commerce management systems are gradually increasing, and transactions are made in various items. However, the reliability between sellers and buyers is very important in high-priced transactions such as automobiles when used transactions online. Nevertheless, in the existing used trading system, a device that prevents fraud or trusts the seller is insufficient. This paper developed a blockchain-based used transaction management system to improve the reliability that occurs during used transactions. We have improved the safety trading system by developing a trading management system for used cars with the highest amount of used cars in various fields. This system uses Ethereum-based smart contract to guarantee reliability without third party intervention. By designing the contracts required for used car trading by utilizing smart contracts, it was possible to reduce the effort and time of trading participants in the existing used car transactions, while enabling safe transactions. In addition, this system mitigated information asymmetry between buyers and sellers, and reduced and prevented brokerage fees in the distribution process without third parties.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.235-241
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• 2019

The structure of the IoT can be divided into devices, gateways, and servers. First, the gateway collects data from the device, and the gateway sends data to the server through HTTP protocol, Websocket protocol, and MQTT protocol. The processing server then processes, analyzes, and transforms the data, and the database makes it easy to store and use this data. These IoT services are basically centralized structures with servers, so attacks on the entire platform are concentrated only on the central server, which makes hacking more successful than distributed structures. One way to solve this problem is to develop IoT that combines blockchain. Therefore, the proposed research suggests that the blockchain is a distributed structure, in which blocks containing small data are connected in a chain form, so that each node agrees and verifies the data with each other, thereby increasing reliability and lowering the probability of data forgery.

• Journal of IKEEE
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• v.19 no.2
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• pp.133-141
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• 2015

The IMS is an architectural control framework for delivering IP multimedia services such as voice, video, audio and data, the IMS supports not only the mobile communication system but also the existing wired and wireless network based on IP. The network that is integrated by the IMS needs policy-based network management protocol for managing the limited network resources to provide efficient multimedia service. The IMS use additional device called PDF for efficient resource management, but the PDF only uses diameter which is one of the network management protocol such as SNMP and COPS. Many devices use various protocol to manage the limited network resources. There is an algorithm using a variety of protocols such as Diameter, COPS and SNMP to handle the resources management efficiently. We also analyze the performance using the proposed algorithm in the implemented IMS environment.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.455-461
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• 2020

Electronic payment system using Internet banking is a very important application for users of e-commerce environment. With rapidly growing use of fintech applications, the risk and damage caused by malicious hacking or identity theft are getting significant. To prevent the damage, fraud detection system (FDS) calculates the risk of the electronic payment transactions using user profiles including types of goods, device status, user location, and so on. In this paper, we propose a new risk calculation method using relative location of users such as SSID of wireless LAN AP and MAC address. Those relative location information are more difficult to imitate or copy compared with conventional physical location information like nation, GPS coordinates, or IP address. The new method using relative location and cumulative user characteristics will enable stronger risk calculation function to FDS and thus give enhanced security to electronic payment systems.

• The Journal of the Convergence on Culture Technology
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• v.4 no.1
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• pp.27-32
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• 2018

Recently, diverse bio-growth and object production experience learning contents have been developed for AR-based storytelling. In this paper, we will develop a storytelling-based growth type content using 3D printer which can add interest in and motivation of experiential learning. It is possible to increase the value of the characters produced by 3D printer as they can be used as personal collections. The bio-growth type content enables the learners and users to experience the local culture, history, and tourism ecology, which can enhance the educational effect by promoting their understanding in a fun way. The purpose of this study is to develop an application for experiential learning contents which creates a virtual environment in an object smart device where you can experience the culture and ecology of a learning community, and then produce the output using the 3D printer to keep as a personal souvenir. The developed contents application for experiential learning can be utilized not only for students but also for tourists. It is expected to serve as a source for further development of various contents through 3D printing technology.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.797-802
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• 2020

Over the past few years, smart devices, including smartphones, have been continuously required by users based on portability. The performance is improving. Ubiquitous computing environment and sensor network are also improved. Due to various network connection technologies, mobile terminals are widely used. Smart terminals need technology to make energy monitoring more detailed for more stable operation during use. The smart terminal which is light in small size generates the power shortage problem due to the various multimedia task among the terminal operation. Various estimation hardwares have been developed to prevent such situation in advance and to operate stable terminals. However, the method and performance of estimating the remaining amount are not relatively good. In this paper, we propose a method for estimating the remaining amount of smart terminals. The Capacity Estimation of lithium ion cells for stable operation was estimated based on machine learning. Learning the characteristics of lithium ion cells in use, not the existing hardware estimation method, through a map learning algorithm using machine learning technique The optimized results are estimated and applied.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.703-708
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• 2020

As the risk of earthquakes increases recently, earthquake-resistant designs were getting interest. For this reason, this study applies that Friction pendulum-type seismic isolator is a device that attenuates seismic energy by friction and pendulum motion. The friction pendulum-type seismic isolator of this study is very easy to transport, install and maintain with light weight of metal by applying the slider using high strength engineering plastic. In addition, there is an advantage that the corrosion resistance is very excellent compared to the existing metal parts. However, there is concern about long-term durability by replacing metal materials. In this study, the frictional pendulum-type seismic isolator with EP was applied to compressive-shear test, repeated fatigue test, and ultimate load test after fatigue test, and analyzed the deformation and shear or properties after the test. As the results, the adequacy of long term fatigue durability was experimentally proven.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.94-102
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• 2015

Optical camera communication (OCC) is an extension of Visible Light Communication. Different from traditional visible light communication, optical camera communications is an almost no additional cost technology by taking the advantage of build-in camera in devices. It was became a candidate for communication protocol for IoT. Camera module can be easy attached to IoT device, because it is small and flexible. Furthermore almost smartphone equip one or two camera for both back and font side with high quality and resolution. It can be utilized for receiving the data from LED or positioning. Actually, OCC combines illumination and communication. It can supply communication for special areas or environment where do not allow Radio frequency such as hospital, airplane etc. There are many concept and experiment be proposed. In this paper we proposed utilizing Android smart-phone camera for receiver and introduce new approach in modulation scheme for LED at transmitter. It also show how Manchester coding can be used encode bits while at the same time being successfully decoded by Android smart-phone camera. We introduce new data frame format for easy decoded and can be achieve high bit rate. This format can be easy to adapt to performance limit of Android operator or embedded system.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.286-291
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• 2020

In this paper, we propose a system that recommends music through tempo-oriented music classification and sensor-based human activity recognition. The proposed method indexes music files using tempo-oriented music classification and recommends suitable music according to the recognized user's activity. For accurate music classification, a dynamic classification based on a modulation spectrum and a sequence classification based on a Mel-spectrogram are used in combination. In addition, simple accelerometer and gyroscope sensor data of the smartphone are applied to deep spiking neural networks to improve activity recognition performance. Finally, music recommendation is performed through a mapping table considering the relationship between the recognized activity and the indexed music file. The experimental results show that the proposed system is suitable for use in any practical mobile device with a music player.