• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.34-41
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• 2011

At present wireless internet access service is available through the 3G network, mobile WiMAX and WiFi anytime and anywhere. In this environment where there are various networks, users should be able to select specific networks depending on different situations. And it is necessary to provide mobility support between homogeneous and between heterogenous networks. Given this situation, the many proposals have been presented to link 3G, which has the largest service area among various networks, with mobile WiMAX(IEEE 802.16e), or with WiFi(IEEE 802.11). But, recently, with the increasing volume of wireless internet use and wireless internet data, due to the advents of net-book, e-book and smart phone, the service area of WiFi and mobile WiMAX has rapidly expanded. Especially, the availability of real-time application such as internet phone has led to the relative shrinking of the proportion of 3G mobile communication network giving conventional voice service, and enlargement of those of wireless internet access networks like WiFi and mobile WiMAX. This paper suggests a handover scheme based on PMIPv6, whitch support mobility between WiFi and mobile WiMAX, and minimizes handover delay. In this scheme, the mobile node has a dual stack structure composed of two interfaces-WiFi and mobile WiMAX. Since WiFi dose not support mobility, it is suggested that the mobile node have the capacity to deal with handover signaling between gateway in case of handover between homogeneous networks. This handover scheme, suggested comparing with current handovers between homogeneous networks, has proved, in its analytic evaluation, to be able to reduce handover, transmission, and signaling overhead.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.3-12
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• 2015

Recently, various studies have been attempted to provide a biological information monitoring service through integrating with the web service. The medical information transmission standard ISO/IEEE 11073 PHD defines the optimized exchange protocol ISO/IEEE 11073-20601 based on the No-IP to exchange the biometric information between the ISO/IEEE 11073 agent and the manager. It's system structure based on the No-IP using ISO/IEEE 11073-20601 is not suitable for providing a remote biological information monitoring services. That is because it is difficult to provide to control and manage the biological information measurement devices, which have installed IP protocol stack at the remote. Furthermore, ACSE and CMDISE in ISO/IEEE 11073-20601 are not suitable to provide U-healthcare services based on IoT because they are complicated and difficult to implement it caused by the structural complexity. In order to solve the problems, in this paper, we propose the biological information monitoring architecture based on ISO/IEEE 11073 DIM/REST of IoT environment to provide the biological information monitoring service based on IoT. To do this, we designed biological information monitoring system architecture based on IoT and the message exchange protocol of ISO/IEEE 11073 DIM/REST between the ISO/IEEE 11073 agent and the ISO/IEEE 11073 manager. In order to verify the realistic possibility of the proposed system architecture, we developed the service prototype.

• Journal of Veterinary Clinics
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• v.27 no.3
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• pp.262-267
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• 2010

Magnesium ($Mg^{2+}$) is an essential co-factor for over 325 physiological and biochemical processes so that plays a central role of neuronal activity, cardiac excitability, neuromuscular transmission, muscular contraction, vasomotor tone, and blood pressure significantly related to physical performance. However, only limited information on blood ionized $Mg^{2+}$ ($iMg^{2+}$) regarding to physical exercise is available and the data from blood total $Mg^{2+}$ detection are inconsistent. This present study investigated the changes of blood $iMg^{2+}$ correlated with metabolic demands during acute high-intensive exhaustive physical exercise in rats. After exhausted swimming (3-4 hours), blood pH, glucose, $HCO_3{^-}$, oxygen and ionized $Ca^{2+}$ ($iCa^{2+}$) were significantly decreased, whereas lactate, carbon dioxide, $iMg^{2+}$, ionized $Na^+$ and ionized $K^+$ were significantly increased. During the exhausted swimming, the changes in $iMg^{2+}$ showed a significant negative correlation with changes in pH, glucose, $HCO_3^-$ and $iCa^{2+}$, however a significant negative correlation with changes in lactate and anionic gap. It is concluded that the acute high-intensive exhaustive physical exercise could produced hypermagnesemia, an increase in blood $iMg^{2+}$ via stimulation of $iMg^{2+}$ efflux following increase in intracellular $iMg^{2+}$ from muscle induced by metabolic and respiratory acidosis.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.18-23
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• 2010

Ferromagnetic resonance (FMR) measurement is an important experimental technique for the study of magnetic dynamics. We designed and set up the vector network analyzer ferromagnetic resonance (VNA-FMR) measurement system with home made coplanar waveguides (CPW). We examined 10-, 20-, 40-nm thick Py thin films to test the performance of the VNA-FMR measurement system. We measured S-parameter (transmission/reflection coefficient) of Py thin films on a CPW. Resonance frequency is investigated from 2.5 to 7 GHz for a field range from 0 to 490 Oe. The VNA-FMR data shows the resonance frequency increment when the external magnetic field increases. We also investigated Gilbert damping constant of Py thin film using resonance frequency (${\omega}_r$) and linewidth ($\Delta\omega$). After investigating dependence of thickness, we find that an decrease in S-parameter intensity as Py thin film thickness decreases. And the FMR results show that the effective saturation magnetization, $M_{eff}$, increase from 7.205($\pm$0.013) kOe to 7.840($\pm$0.014) kOe, while the film thickness varies from 10 to 40 nm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.198-201
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• 2015

The prompt and accurate location determination of the nodes of the wireless indoor shipboard networks is crucial to forming the stable wireless shipboard sensor networks. To this end in this paper it can be achieved through the measurement of the bi-directional channel qualities among the nodes after the locations of the sensor nodes temporarily placed. For the 1st stage the piconet-type sensor networks are considered to measure the channel qualities between a specific node and the cluster node which is the master node. After finishing the 1st stage measurement the nodes needing the relay nodes are selected and the measurement action goes into the 2nd stage. In the 2nd stage the measurement between a candidate relay node and the node needing a relay node starts to begin. After the 2nd stage the relay nodes to connect to the cluster node are fixed and the information delivery paths between a node and the cluster head are established. In this paper the measurement results in the realistic environment are gathered and analysed to show that the measurement procedure can be applied in the wireless indoor shipboard networks.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.134-142
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• 2003

We present an ATM switch architectures based on the multistage interconnection network(MIN) for the efficient multicast traffic control. Many of these applications require multicast connections as well as point-to-point connections. Muiticast connection in which the same message is delivered from a source to arbitrary number of destinations is fundamental in the areas such as teleconferencing, VOD(video on demand), distributed data processing, etc. In designing the multicast ATM switches to support those services, we should consider the fairness(impartiality) and priority control, in addition to the overflow problem, cell processing with large number of copies, and the blocking problem. In particular, the fairness problem which is to distribute the incoming cells to input ports smoothly is occurred when a cell with the large copy number enters upper input port. In this case, the upper input port sends before the lower input port because of the calculating method of running sum, and therefore cell arrived into lower input port Is delayed to next cycle to be sent and transmission delay time becomes longer. In this paper, we propose the cell splitting and group splitting algorithm, and also the fairness scheme on the basis of the nonblocking characteristics for issuing appropriate copy number depending on the number of Input cell in demand. We evaluate the performance of the proposed schemes in terms of the throughput, cell loss rate and cell delay.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.103-113
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• 2019

License plate recognition camera is dedicated device designed for acquiring images of the target vehicle for recognizing letters and numbers in a license plate. Mostly, it is used as a part of the system combined with server and image analysis module rather than as a single use. However, building a system for vehicle license plate recognition is costly because it is required to construct a facility with a server providing the management and analysis of the captured images and an image analysis module providing the extraction of numbers and characters and recognition of the vehicle's plate. In this study, we would like to develop an embedded type convergent camera (Edge Base) which can expand the function of the camera to not only the license plate recognition but also the security CCTV function together and to perform two functions within the camera. This embedded type convergence camera equipped with a high resolution 4K IP camera for clear image acquisition and fast data transmission extracted license plate area by applying YOLO, a deep learning software for multi object recognition based on open source neural network algorithm and detected number and characters of the plate and verified the detection accuracy and recognition accuracy and confirmed that this camera can perform CCTV security function and vehicle number plate recognition function successfully.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.50-60
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• 2018

In this paper, we developed a broadband multi-layered radome applicable for high-power applications. In this regard, we presented the wave propagation characteristics of the broadband multi-layered radome with the ABCD matrix and obtained the optimal thickness and the material constant for each layer by an optimization algorithm called "particle swarm optimization," implemented by a commercial numerical modeling tool. Further, we redesigned it in view of mechanical properties to reflect environmental conditions such as wind, snow, and ice. The power transmission property was reanalyzed based on the recalculated data of each layer's thickness to consider the limitations of the fabrication of a large structure. Under the condition of a peak electric field strength that is 10 dB above the critical electric field strength in air breakdown, we analyzed the air breakdown by radio frequency(RF) in the designed radome using the commercial full-wave electromagnetic tool. The radome was manufactured and tested by continuous wave(CW) RF small signal and large signal in an anechoic chamber. The test results showed good agreement with those attained by simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.35-45
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• 2006

Coordinator is defining so that function as most trust center that is point in security in ZigBee Alliance. Because must do height connection with coordinator in device signing to PAN newly, coordinator has shortcoming that subordinate is revealed to danger directly to Centered and cattish device. When do height connection some device, do not become problem, but if network is huge, coordinator's subordinate shall increase as traffic quantity which happen in coordinator increases. Also, in ZigBee security to link network kina of transmission and mutually certification in ZigBee Alliance standard include, but I do not provide method to deliver master key in each node safely. Because process that transmit master key passes through channel that do not secure, master key has shortcoming that is revealed directly. In this paper, I suggested Parent-Child key establishment algorithm to solve these problem. Proposed algorithm consists of two structures. Master key establishment algorithm and device that sign to PAN newly that can use one-way Hash chain and transmit master key safety are consisted of Parent-Child network key establishment algorithm that do child node and parent node key establishment as can do key establishment efficiently. Method that device proposes in case method that propose in case have master key establishment time was shown better performance $200{\sim}1300ms$ than existing method, and device does not have master key than existing method height connect time about $400{\sim}500ms$ better performance see.