• KIPS Transactions on Computer and Communication Systems
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• v.7 no.10
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• pp.259-268
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• 2018

Due to the development of cities and the increase of vehicles, effective control of parking space management service in cities is needed. However, the existing parking lot management system does not provide limited or convenient service in terms of space and time. In this paper, we propose distributed parking space management service based on large scale LPWA (Low-Power Wide-Area). The parking sensor collects parking space information from the parking lot and is transmitted over a low-power wide network. All parking data is processed and analyzed in the IoT cloud. Through a parking space management service system in all cities, users are given the temporal convenience of determining the parking space and the area efficiency of the parking space.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.430-436
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• 2019

It is needed to develop an antenna with features of subminiature, light weight and multi-band operation for the variaty services in maritime and industrial fields. The PCB pattern antenna is one of the appropreiate antennas solving these requirements. In this research, the design and fabrication of the PCB pattern antenna operating on the single band of 920 MHz are investigated. The final goal is that the development of the dual band PCB pattern antenna operating on 260 MHz and 920 MHz, which is based on the proposed antenna. It is evident that the performance in the frequencies of 902 MHz, 915 MHz and 928 MHz among of 920 MHz ISM band is better than that in other frequencies. It is also confirmed that the differences of the voltage standing wave ratio, return loss, gain and efficiency between three frequencies are less than 5%. It is expected that the development of communication link of 5-10 km is possible when the induced results are applied into the low power wide area (LPWA) network desinged by the rule of -30 dB sensitivity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.3-16
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• 2010

Recently in the field of the wireless sensor network, many researchers are attracted to pairing cryptography since it has ability to distribute keys without additive communication. In this paper, we propose efficient hardware implementation of ${\eta}_T$ pairing which is one of various pairing scheme. we suggest efficient hardware architecture of ${\eta}_T$ pairing based on parallel processing and register/resource optimization, and then we present the result of our FPGA implementation over GF($2^{239}$). Our implementation gives 15% better result than others in Area Time Product.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.194-198
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• 2021

LoRa is a physical layer technology that is designed to provide a reliable long-range communication with introducing CSS and with introducing a loco parentis tree network. Since a leaf can utilize multiple parents at the same time with a single transmission, PDR increases logarithmically as the number of gateways increases. Because of the ALOHA-like MAC of LoRa, however, the PDR degrades even under the loco parentis tree topology similarly to the single-gateway environment. Our proposed method is aimed to achieve SDMA approach to reuse the same frequency in different areas. For that purpose, it elaborately controls each TxPower of the senders for each message in concurrent transmission to survive the collision at each different gateway. The gain from this so-called capture effect increases the capacity of resource-hungry LPWAN. Compared to a typical collision-free controlled-access scheme, our method outperforms by 10-35% from the perspective of the total count of the consumed time slots. Also, due to the power control mechanism in our method, the energy consumption reduced by 20-40%.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.631-638
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• 2015

The purpose of this study is to provide developmental direction of medical education by analysing graduate medical school student's perception structure about 'good doctor' and the difference between graduate medical school student's perception structure about 'good doctor' before and after clerkship. Subject of study is medical students in 1st~4th year. NetMiner 4.0 program, which is social network analysis, was used to analyse. Many of the words that students used to describe good doctor were similar. But especially lots of times they used 'patient', 'treatment', 'competence', 'heart' and a word 'patient' showed highest degree centrality. Higher density of network and mean degree centrality were shown in students who experienced clerkship. 'Diagnosis and treatment', 'medical communication', 'attitudes to patients', 'medical knowledge', 'basic competence' these 5 groups were shown in network of students before and after clerkship in common. In the case of students after clerkship, 'lifelong learning ' groups have been added, so were the 6 groups. Considering the fact that social responsibility, professionalism, medical humanities are emphasized in recent medical education, students have lack of perception structure about good doctor, therefore education of this area needs to be strengthened.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9C
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• pp.939-948
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• 2005

In EBCOT, the context extraction process takes excessive calculation time and this paper proposed a method to reduce this calculation time. That is, if a coefficient is less than a pre-defined threshold value the coefficient and its descendents skip the context extraction process. There is a trade-off relationship between the calculation time and the image quality or the amount of output data such that as this threshold value increases, the calculation time and the amount of output data decreases, but the image degradation increases. Therefore, by deciding this threshold value according to the network environments or conditions, it is possible to establish a network-adaptive context extraction method. The experimental results showed that the range of the threshold values for acceptable image quality(better than 30dB) is from 0 to 4. The experimental results showed that in this range the Resulting reduction rate in calculation time was from $3\%\;to\;64\%$ in average, the reduction rate in output data was from $32\%$ to $73\%$ in average, which means that large reduction in calculation time and output data can be obtained with a cost of an acceptable image quality degradation. Therefore, the proposed method is expected to be used efficiently in the application area such as the real-time image/video data communication in wireless environments, etc.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.25-36
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• 2016

The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a "JRS-MS" (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.437-441
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• 2006

Wireless sensor network consists of sensor nodes which are disseminated closely to each other to collect informations for the various requests of a sensor application applied for sensing phenomenons in real world. Each sensor node delivers sensing informations to an end user by conducting cooperative works such as processing and communicating between sensor nodes. In general, the power supply of a sensor node is depends on a battery so that the power consumption of a sensor node decides the entire life time of a sensor network. To resolve the problem, optimal routing algorithm can be used for prolong the entire life time of a sensor network based on the information on the energy level of each sensor node. In this paper, different from the existing Directed Diffusion and SPTN method, we presents a data dissemination protocol based on lower-power consumption that effectively maximizes the whole life time of a sensor network using the informations on the energy level of a sensor node and shortest-path hops. With the proposed method, a data transfer path is established using the informations on the energy levels and hops, and the collected sensing information from neighboring nodes in the event-occurring area is merged with others and delivered to users through the shortest path.

• Smart Media Journal
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• v.8 no.2
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• pp.29-38
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• 2019

With the advancement of information and communication technology, tactical networks are continuously being converted to All-IP future tactical networks that integrate all application services based on Internet protocol. Futuristic tactical mesh network is built with tactical WAN (wide area network) nodes that are inter-connected by a mesh structure. In order to guarantee QoS (quality of service) of application services, tactical service mesh (TSM) is suggested as an intermediate layer between infrastructure and application layers for futuristic tactical mesh network. The tactical service mesh requires dynamic QoS monitoring and control for intelligent QoS coordination. However, legacy networking nodes used for existing tactical networks are difficult to support these functionality due to inflexible monitoring support. In order to resolve such matter, we propose a tactical mesh WAN node as a hardware/software co-designed networking node in this paper. The tactical mesh WAN node is conceptually designed to have multi-access networking interfaces and virtualized networking switches by leveraging the DANOS whitebox server/switch. In addition, we explain how to apply eBPF-based traffic monitoring to the tactical mesh WAN node and verify the traffic monitoring feasibility for supporting QoS coordination of tactical-mesh traffic.

• Journal of Convergence for Information Technology
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• v.11 no.4
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• pp.26-34
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• 2021

In the era of the Fourth Industrial Revolution, the future battlefield will carry out multi-area operations with hyper-connected, high-speed and mobile systems. In order to prepare for changes in the future, the Korean military intends to develop various weapons systems and form a multi-layer tactical network to support On The Move communication. However, current tactical networks are limited in support of On The Move communications. In other words, the operation of multi-beam antennas is necessary to efficiently construct a multi-layer tactical network in future warfare. Therefore, in this paper, we look at the need for multi-beam antennas through the operational scenario of a multi-layer tactical network. In addition, based on development consideration factors, features of rotary-wing and fixed-wing aircraft, we present the location and operation of airborne relay drone installations of multi-beam antennas.