• Journal of Korea Multimedia Society
• /
• v.10 no.8
• /
• pp.1029-1038
• /
• 2007

A smart card based on the existing Java card platform executes and installs an application only when the power is supplied for a minute. And preparing for unexpected power outrage, the execution state of an application and all the data that are modified during execution are saved in the heap. This kind of frequent data update of an EEPROM data is a main cause of reducing the life-cycle of a smart card. This is because the smart card has been developed not considering the current situation that the power is always supplied, and by this time it has continuously kept its old architecture. This paper explains the high performance Java card system free power restriction. The system improves not only application saving mechanism, but memory architecture. In special, we deploy RAM for running an applet, as well as EEPROM for downloading an application. Through proposed mechanism, we can find out performance evaluation that the creation speed of an applet and the execution speed of a method increase up to 58% and 33% respectively.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.4
• /
• pp.147-159
• /
• 2015

This paper is to design smart based collaborative learning model for programming education of fifth graders of elementary school and applies it to a class and analyze its result. Designed learning model is composed of understanding of concept, realization, learning and sharing and it includes step by step learning materials and smart based collaborative learning activities. Scratch traffic light learning materials at leaning stage classify content to be checked in programming by colors and write to support programming internalization of learners. Provision of smart based collaborative learning activities that considered learning conditions of learners makes it possible for beginners to participate in and keep study actively. This study showed that there was statistically significant difference in learners' programming interest and those who achieved over 8 out of 10 points were 60.7% at three stage evaluations for achievement level that applied learning model which suggests that satisfactory achievement level is achieved.

• Journal of Advanced Navigation Technology
• /
• v.19 no.1
• /
• pp.66-73
• /
• 2015

In this paper, an architecture of a perpetual smart video device and its energy control model for the internet of things (IoT) are proposed. The smart video device consists of a processor, an image sensor, a video codec, and a network controller. In the proposed energy control model, energy consumed by image sensing, video encoding, and transmission and energy harvested by solar panels are defined as an input and an output of a battery, an energy buffer. Frame rate, quantization parameter, and operating frequency of processor are defined as the energy control parameters, and these parameters control the input and the output energy of the energy buffer, finally control the energy left in the battery. The proposed energy control model is validated by the energy consumption measurement of the smart phone based platform for various combinations of energy control parameters, and can be used for the design of perpetual smart video device.

• Journal of the Institute of Convergence Signal Processing
• /
• v.19 no.3
• /
• pp.89-96
• /
• 2018

This study aims to develop a fully passive smart sensing tag utilizing RF (Radio Frequency) energy harvesting technology at UHF (Ultra High Frequency) band of 915MHz. To optimize the power collected under various radiated conditions, an efficient energy harvesting module exploiting a boost circuit with maximum power point tracking (MPPT) is employed. Specifically, the proposed tag features two orthogonal antennas to enhance its capability of both energy scavenging and data transmissions. The experimental result shows that the developed smart sensor tag can scavenge an RF input power of as low as 0.19mW at a distance of 4 meters for a 3.6Vdc output. Furthermore, the proposed smart sensor tag performs the feasibility of completely autonomous monitoring food freshness at 2 meters with a low-power sensor array.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.11
• /
• pp.2418-2423
• /
• 2012

A smart phone which is one of the new IT technologies can be viable on various enterprise applications since it provides easily information and services. Especially, a smart phone can request queries to a server which finds massive data for decision making and receive the results of the queries from the server. However, a smart phone has a drawback that its battery is consumed easily due to the 4G communication. In this paper, we propose mobile views in order to reduce the easy consumption of a battery on mobile client-server environment. The proposed mobile view scheme reduces the number of communication which is leading to power consumption using materialized views for processing queries. We also classify the methods to control the consistency of the mobile view as the sources of the view are changed and present the cost of each method based on the cost model of battery consumption.

• Journal of Internet Computing and Services
• /
• v.20 no.6
• /
• pp.157-166
• /
• 2019

oneM2M has been adopted to national and global smart city platforms leveraging its benefits, oneM2M platform assures interoperability to devices and services with standard APIs. Existing access control mechanisms in the standard should be extended to easily distribute smart city data. Compared to the as-is standard, this paper proposes a new access control method with minimum human interventions during data distribution between data sellers and buyers. The proposal has been implemented as the new data marketplace APIs to oneM2M platform and used for data marketplace portal interworking. This also has been demonstrated with smart city PoC service.

• Journal of Digital Convergence
• /
• v.14 no.2
• /
• pp.259-264
• /
• 2016

In this paper, we proposed an arduino-based smart green house management system model and implemented it. The proposed system consists of control unit composed of sensors and arduino, agent program controlling the green house, and web applications providing user interfaces. The control unit transmits data of sensors such as temperature, humidity, illuminance, moisture, etc. to the agent program, and then the agent saves the data in its database. In reverse, control data are transmitted from agent program to control unit. Users can monitor sensed data of green houses and control actuators remotely using web. Plus, smart green house management is available by context awareness and autonomous control functions of the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.1B
• /
• pp.75-85
• /
• 2012

In this paper, we introduce the case study on the certificate system for Auto Meter Reading protocol, Device Language Message Specification which is a common language between metering devices and protocol with compatibility and conformance to the IEC 62056 standards. KEPCO has contributed to improve interoperability between different devices of multi vendors through the DLMS standard tests and led the smart metering industry in Korea. KEPCO has AMR system and successful business model for 550 thousands of households based on 24Mbps broadband powerline communications using its infrastructure. We have plan to continue on standardization activities stratagemically by participating in IEC working groups for the purpose of occupying the core technology of Smart Gird.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.4
• /
• pp.758-767
• /
• 2017

IoT paradigm which makes a information without direct intervention of a human and interworks with other objects, humans and systems is attracting attention. It will be expected the number of smart devices equipped with sensors and wireless communication capabilities is reached to about 260 billion by 2020. With the vast amount of sending data generated from rapidly increasing number of smart devices, it will bring up the traffic growth over internet and congestion in wireless networks. In this paper, we utilize the smart device as a sink node to collect and forward the sensing data periodically in IoT and propose a heuristic algorithm for a selection of sink nodes' set with each sink node satisfies the QoS its applications because a selection of optimal sink nodes' set is NP-hard problem. The complexity of proposed heuristic algorithm is $O(m^3)$ and faster than the optimal algorithm.

• Journal of Digital Contents Society
• /
• v.19 no.7
• /
• pp.1237-1244
• /
• 2018

Currently the bottleneck in virtual reality's commercialization might be that high cost VR equipment is needed and interesting VR contents are not enough. The purpose of this paper is to solve these problems by implementing low-cost VR system with wireless controller and HMD(Head Mounted Display) using a smart phone and PC. The functions of real HMD are simulated by utilizing the display and embedded sensors of a smart phone. In that situation PC is in charge of processing huge data and is communicated with smart phone. And wireless controller is designed to make VR user's movement to be free. In addition, we made the several VR contents for testing our prototype system directly. Easy access to VR equipment could induce increasing number of users and investment. And it will be a big step toward improving VR technology and its commercialization.