• Journal of Advanced Navigation Technology
• /
• v.7 no.1
• /
• pp.59-71
• /
• 2003

The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.2
• /
• pp.103-112
• /
• 2010

In sensor networks, because sensors are deployed in an unprotected environment, they are prone to be targets of compromise attack, If the number of compromised nodes increases considerably, the key management in the network is paralyzed. In particular, compromise of Cluster Heads (CHs) in clustered sensor networks is much more threatening than that of normalsensors. Recently, rekeying schemes which update the exposed keys using the keys unknown to the compromised nodes are emerging. However, they cause some security and efficiency problems such as single group key employment in a cluster, passive eviction of compromised nodes, and excessive communication and computation overhead. In this paper, we present a proactive rekeying scheme using renewals of duster organization for clustered sensor networks. In the proposed scheme, each sensor establishes individual keys with neighbors at network boot-up time, and these keys are employed for later transmissions between sensors and their CH. By the periodic cluster reorganization, the compromised nodes are expelled from network and the individual keys employed in a cluster are changed continuously. Besides, newly elected CHs securely agree a key with sink by informing their members to sink, without exchangingany keying materials. The simulation results shows that the proposed scheme remarkably improves the confidentiality and integrity of data in spite of the increase of compromised nodes. Also, they show that the proposed scheme exploits the precious energy resource more efficiently than SHELL.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.267-275
• /
• 2018

The dredged sediment management system was developed to have an objective, quantitative and scientific decision for the optimum removal time of dredged sediments behind debris barrier and was set up at the real site. The dredged sediment management system is designed and developed to directly measure the dredged sediments behind debris barrier in the field. This management system is composed of Data Acquisition System (DAS), Solar System and measurement units for measuring the weight of dredge sediments. The weight of dredged sediments, the water level and the rainfall are measured in real time using the monitoring sensors, and their data can be transmitted to the office through a wireless communication method. The monitoring sensors are composed of the rain gauge to measure rainfall, the load cell system to measure the weight of dredged sediments, and water level meter to measure the water level behind debris barrier. The management criteria of dredged sediments behind debris barrier was suggested by using the weight of dredged sediments. At first, the maximum weight of dredged sediments that could be deposited behind debris barrier was estimated. And then when 50%, 70% and 90% of the maximum dredged sediments weight were accumulated behind debris barrier, the management criteria were divided into phases of Outlooks, Watch and Warning, respectively. The weight of dredged sediments can be monitored by using the dredged sediment management system behind debris barrier in real time, and the condition of debris barrier and the removal time of dredged sediments can be decided based on monitoring results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.531-534
• /
• 2014

DLNA is an established industry standard which supports contents sharing among smart devices in home wired- and wireless-network environment and is well known in Korea as Allshare or Smartshare. The DLNA standard is implemented as built-in services in most of Android smart phones and tablets. In addition to the handheld devices, DLNA service can also be employed in speakers, printers, and so on. However, users have reported many interoperability issues between DLNA devices. Developers typically identify causes by analyzing the packet exchange information between devices. However, this approach costs them to put additional effort to filter relevant packets, to reconstruct packet exchange history and the protocol flow. Consequently, it ends up with increased development time. In this paper, we demonstrate a technique to automatically analyze and visualize the packet exchange history. We modified a router firmware to capture and store packets exchanged between DLNA devices, and then analyze and visualize the stored packet exchange history for developers. We believe that visualized packet exchange history can help developers to test the interoperability between DLNA devices with less effort, and ultimately to improve the productivity of developers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.299-302
• /
• 2014

Due to the convergence between digital devices and the development of wireless communication technology, bit-signal sensor miniaturization, building an Electronic Medical Record (EMR) which is a digital version of a paper chart that contains all of a patient's medical history and the information of Electronic Health Record (EHR), Ubiquitous healthcare (u-Healthcare) that can monitor their health status and provide personal healthcare service anytime and anywhere. Also, the appearance of cloud computing technology is one of the factors that accelerate the development of u-healthcare service. However, if the individual information to be used maliciously during the u-healthcare service utilization, leads to serious problems directly related to the individual's life because if it goes beyond the level of simple health screening and treatment, it may not provide accurate and reliable healthcare services. For this reason, we analyzed a variety of security issues related to u-healthcare service in cloud computing environment and described about directions of secure health information sharing system construction. In addition, we suggest the future developmental direction for th activation of u-healthcare industry.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.504-509
• /
• 2019

Recently, both wireless communications technology and the performance of small devices have developed exponentially, while the number of services using various types of Internet of Things (IoT) devices has also massively increased in line with the ongoing technological and environmental changes. Furthermore, ever more devices that were previously used in the offline environment-including small-size sensors and CCTV-are being connected to the Internet due to the huge increase in IoT services. However, many IoT devices are not equipped with security functions, and use vulnerable open source software as it is. In addition, conventional network equipment, such as switches and gateways, operates with vulnerabilities, because users tend not to update the equipment on a regular basis. Recently, the simple vulnerability of IoT devices has been exploited through the distributed denial of service (DDoS) from attackers creating a large number of botnets. This paper proposes a system that is capable of identifying Internet-connected devices quickly, analyzing and managing the vulnerability of such devices using Internet-wide scan technology. In addition, the vulnerability analysis rate of the proposed technology was verified through collected banner information. In the future, the company plans to automate and upgrade the proposed system so that it can be used as a technology to prevent cyber attacks.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.4
• /
• pp.77-83
• /
• 2019

With the increase in population, the number of such senior citizens is increasing day by day. These senior citizens have a variety of care needs, but there are not enough health workers to look after them. Ambient Assisted Living (AAL) aims at ensuring the safety and health quality of the older adults and extending the number of years the senior citizens can live independently in an environment of their own preference. AAL provides a system comprising of smart devices, medical sensors, wireless networks, computer and software applications for healthcare monitoring. AAL can be used for various purposes like preventing, curing, and improving wellness and health conditions of older adults. While information security and privacy are critical to providing assurance that users of AAL systems are protected, few studies take into account this feature. In this paper, we propose a secure and lightweight authentication scheme for the AAL systems. The proposed authentication scheme not only supports several important security requirements needed by the AAL systems, but can also withstand various types of attacks. Also, the security analysis results are presented to show the proposed authentication scheme is more secure and efficient rather than existing authentication schemes.

• Journal of Convergence for Information Technology
• /
• v.10 no.12
• /
• pp.15-21
• /
• 2020

Although IoT systems are used in a variety of heterogeneous environments as cloud environments develop, all IoT devices are not provided with reliable protocols and services. This paper proposes an IoT data management technique that can extend the IoT cloud environment to an n-layer multi-level structure so that information collected from different heterogeneous IoT devices can be efficiently sorted and processed. The proposed technique aims to classify and process IoT information by transmitting routing information and weight information through wireless data link data collected from heterogeneous IoT devices. The proposed technique not only delivers information classified from IoT devices to the corresponding routing path but also improves the efficiency of IoT data processing by assigning priority according to weight information. The IoT devices used in the proposed technique use each other's reliable protocols, and queries for other IoT devices locally through a local cloud composed of hierarchical structures have features that ensure scalability because they maintain a certain cost.y channels of IoT information in order to make the most of the multiple antenna technology.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.104-112
• /
• 2021

For extrusion processes in the process industry, the need to build smart factories is increasing. However, in most extrusion production sites, the production method is continuous, and because the properties of the data are undeed, it is difficult to process the data. In order to solve this problem, we present a methodology utilizing a near field communication (NFC) sensor rather than water-based data entry. To this end, a wireless network environment was built, and a data management method was designed. A non-contact NFC method was studied for the production performance-data input method, and an analysis method was implemented using the pivot function of the Excel program. As a result, data input using NFC was automated, obtaining a quantitative effect from reducing the operator's data processing time. In addition, using the input data, we present a case where a bottleneck is improved due to quality problems.

• Journal of Korea Foundry Society
• /
• v.41 no.6
• /
• pp.550-557
• /
• 2021

With the advent of the fourth industrial revolution, the interest in the internet of things (IoT) in manufacturing is growing, even at foundries. There are several types of process data that can be automatically collected at a foundry, but considerable amounts of process data are still managed based on handwriting for reasons such as the limited functions of outdated production facilities and process design based on operator know-how. In particular, despite recognizing the importance of converting process data into big data, many companies have difficulty adopting these steps willingly due to the burden of system construction costs. In this study, the field applicability of IoT-based devices was examined by manufacturing devices and applying them directly to the site of a centrifugal foundry. For the centrifugal casting process, the temperature and humidity of the working site, the molten metal temperature, and mold rotation speed were selected as process parameters to be collected. The sensors were selected in consideration of the detailed product specifications and cost required for each process parameter, and the circuit was configured using a NodeMCU board capable of wireless communication for IoT-based devices. After designing the circuit, PCB boards were prepared for each parameter, and each device was installed on site considering the working environment. After the on-site installation process, it was confirmed that the level of satisfaction with the safety of the workers and the efficiency of process management increased. Also, it is expected that it will be possible to link process data and quality data in the future, if process parameters are continuously collected. The IoT-based device designed in this study has adequate reliability at a low cast, meaning that the application of this technique can be considered as a cornerstone of data collecting at foundries.