• The Transactions of the Korea Information Processing Society
• /
• v.4 no.6
• /
• pp.1433-1442
• /
• 1997

Algorithm design is needed to optimized bandwidth which satisfy quality of service(QoS) requirements of vary traffic classes for Multimedia service in ATM networks. The diverse flow characteristics e.g., burstiness, bit rate and burst length, have to guarantee the different quality of service(QoS) requirements in Asynchronous Transfer Mode(ATM). The QoS parameter may be measured in terms of cell loss probability and maximum cell dely. In this paper, we consider the ATM networks which the virtual path(vip) concept is implemented by applying the Markov Modulated Deterministic Process method. We develop an efficient algorithm to computer the minimum capacity required to satisfy all the QoS requirements when multiple classes of on-off source are multiplexed on single VP. Using above the result, we propose a simple algorithm to determine the VP combination to achieve the near optimum of total capacity required for satisfying the individual QoS requirements. Numerical results are also presented to demonstrate the performance of the algorithm, when compared to the optimal total capacity required.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.5A
• /
• pp.554-565
• /
• 2004

In this paper, we implement single cycle and multi cycle adders. We can compare area and time by using the implemented adders. The size of adders is 64, 128, 256-bits. The architecture of hybrid adders is that the carry-out of small adder groups can be interconnected by utilizing n carry propagate unit. The size of small adder groups is selected in three formats - 4, 8, 16-bits. These adders were implemented with Verilog HDL with top-down methodology, and they were verified by behavioral model. The verified models were synthesized with a Samsung 0,35(um), 3.3(V) CMOS standard cell library while a using Synopsys Design Compiler. All adders were synthesized with group or ungroup. The optimized adder for a Crypto-processor included Smart Card IC is that a 64-bit RCA based on 16-bit CLA. All small adder groups in this optimized adder were synthesized with group. This adder can operate at a clock speed of 198 MHz and has about 961 gates. All adders can execute operations in this won case conditions of 2.7 V, 85 $^{\circ}C$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.8
• /
• pp.1521-1531
• /
• 2015

According to the service attributes, D2D communications establish 1-1, or 1-n channels and require the differentiated device discovery technology. This paper proposes a sector-based device discovery mechanism for 1-n D2D communication scenario in LTE-Advanced networks that a disaster happened. Our proposal is a mechanism that can extend the coverage in a disaster situation which a number of devices(survivors) need to be discovered in a short time. In the single cell environment, a larger discovery coverage can be obtained, and in the multi-cell, it is possible to mitigate the interference with adjacent links due to sector-based coverage control. Through a set of simulations, we have confirmed that our proposal has better performance in the number of devices discovered and the interference than the legacy broadcast device discover mechanism.

• Journal of Sensor Science and Technology
• /
• v.12 no.2
• /
• pp.79-87
• /
• 2003

In this paper, we propose a method to obtain a linear characteristic using soft computing for systems which have array sensors of nonlinear characteristics. Also a procedure utilizing the pattern information of array sensors without additional sensors is proposed to reduce disturbance effects. For a typical example, even a single CdS cell for CdS array has nonlinear characteristics. Overall linear characteristic for CdS array is obtained using fuzzy logic for each cell and overlapped portion. In addition, further improvement for linearization is obtained applying genetic algorithms for the parameters of membership functions. Also the effect of disturbing external light changes to the CdS array can be reduced without using any additional sensors for calibration. The proposed method based on fuzzy logic shows improvements for position measurements and disturbance reduction to external light changes due to the fuzziness of the shadow boundary as well as the inherent nonlinearity of the CdS array. This improvement is shown by applying the proposed method to the ball position measurements of a magnetic levitation system.

• Proceedings of the IEEK Conference
• /
• 2000.07a
• /
• pp.101-104
• /
• 2000

Nowadays, the issue of congestion control in high-speed communication networks becomes critical in view of the bandwidth-delay products for efficient data flow. In particular, the fact that the congestion is often accompanied by the data flow from the high-speed link to low-speed link is important with respect to the stability of closed-loop congestion control. The Virtual-Connection Network (VCN) in Gigabit Ethernet networks is a packet-switching based network capable of implementing cell- based connection, link-by-link flow-controlled connection, and single- or multi-destination virtual connections. VCN described herein differ from the virtual channel in ATM literature in that VCN have link-by-link flow control and can be of multi-destination. VCNs support both connection-oriented and connectionless data link layer traffic. Therefore, the worst collision scenario in Ethernet CSMA/CD with virtual collision brings about end-to-end delay. Gigabit Ethernet networks based on CSMA/CD results in non-deterministic behavior because its media access rules are based on random probability. Hence, it is difficult to obtain any sound mathematical formulation for congestion control without employing random processes or fluid-flow models. In this paper, an analytical method for the design of a congestion control scheme is proposed based on Smith＇s principle to overcome instability accompanied with the increase of end-to-end delays as well as to avoid cell losses. To this end, mathematical analysis is provided such that the proposed control scheme guarantees the performance improvement with respect to bandwidth and latency for selected network links with different propagation delays. In addition, guaranteed bandwidth is to be implemented by allowing individual stations to burst several frames at a time without intervening round-trip idle time.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.5
• /
• pp.569-578
• /
• 2011

The $SiO_2$ membranes for polymer electrolyte membrane fuel cell (PEMFC) are preapared by electrospinning method. It leads to high porosity and surface area of membrane to accommodate the proton conducting materials. The composite membrane was prepared by impregnating of Nafion ionomer into the pores of electrospun $SiO_2$ membranes. The $SiO_2$:heteropolyacid (HPA) nano-particles as a inorganic proton conductor were prepared by microemulsion process and the particles are added to the Nafion ionomer. The characterization of the membranes was confirmed by field emission scanning electron microscope (FE-SEM), thermogravimetry analysis (TGA), and single cell performance test for PEMFC. The Nafion impregnated electrospun $SiO_2$ membrane showed good thermal stability, satisfactory mechanical properties and high proton conductivity. The addition of the $SiO_2$:HPA nano-particle improved proton conductivity of the composite membrane, which allow further extension for operation temperature in low humidity environments. The composite membrane exhibited a promising properties for the application in high temperature PEMFC.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.5
• /
• pp.376-384
• /
• 2020

An energy storage system is composed of lithium-ion batteries in modern applications. Batteries are regarded as storage devices for renewable and residual energy. The failure of batteries can cause the performance reduction and explosion of battery systems. High maintenance cost is essential when dealing with the problem of battery safety. Therefore an accurate health diagnosis is required to ensure the high reliability of battery systems. A battery pack is a combination of single cells in series and parallel connections. A battery pack has to consider various factors to assess battery health. Battery health involves conventional factors and additional factors, such as cell-to-cell imbalance. For large applications, state-of-health (SOH) can be inaccurate because of the lack of factors that indicate the state of the battery pack. In this study, six characterization factors are proposed for improving the SOH estimation of battery packs. The six proposed characterization factors can be regarded as health indicators (HIs). The six HIs are applied to the principal component analysis (PCA) algorithm. To reflect information regarding capacity, voltage, and temperature, the PCA algorithm extracts new degradation factors by using the six HIs. The new degradation factors are applied to a multiple regression model. Results show the advancement and improvement of SOH estimation.

• Journal of IKEEE
• /
• v.20 no.1
• /
• pp.89-93
• /
• 2016

In this paper, we proposed SIMT based Image Signal Processor which can apply various image preprocessing algorithms and allow parallel processing of application programs such as image recognition. Conventional ISP has the hard-wired image enhancement algorithm of which the processing speed is fast, but there was difficult to optimize performance depending on various image processing algorithms. The proposed ISP improved the processing time applying SIMT architecture and processed a variety of image processing algorithms as an instruction based processor. We used Xilinx Virtex-7 board and the processing time compared to cell multicore processor, ARM Cortex-A9, ARM Cortex-A15 was reduced by about 71 percent, 63 percent and 33 percent, respectively.

• The Journal of Internal Korean Medicine
• /
• v.41 no.6
• /
• pp.1089-1099
• /
• 2020

Objective: The purpose of this study was to investigate the effect of cinnamon on the treatment of Parkinson's disease (PD) and to introduce its use in Korea. Method: We searched the experimental studies in electronic databases (PubMed, CNKI, Wanfang, CiNii, J-STAGE, Science ON, and OASIS) using the key search terms "cinnamic acid", "cinnamon", "cinnamomum", "Parkinson's disease", "Parkinson disease", "Parkinsonism", and "dopamine". This study only involved experimental studies (in vivo and in vitro) that adopted cinnamon as a single administration and measured indicators relating to Parkinson's disease, including parkin, tyrosine hydroxylase (TH), and dopamine. Results: A Total of 11 literature studies were selected, and they all showed that treatment with cinnamon has a neuroprotective effect. Cinnamon activated neuroprotective factors and restored neurotransmitters and it reduced the rate of oxidative stress and inflammation in neurons. As a result, cell viability was upregulated, while cell apoptosis and neurodegeneration were downregulated. Five in vivo studies, through behavioral tests, also confirmed that cinnamon recovers locomotor function in PD models. Conclusion: We identified that cinnamon is an effective neural protector and improves motor performance in behavioral testing in the experimental PD studies.

• Applied Chemistry for Engineering
• /
• v.33 no.1
• /
• pp.96-102
• /
• 2022

Reactants of PEMFC are hydrogen and oxygen in gas phases and fuel cell overpotential could be reduced when reactants are smoothly transported. Numerous studies to modify cathode flow field design have been conducted because oxygen mass transfer in high current density region is dominant voltage loss factor. Among those cathode flow field designs, a block in flow field is used to forced supply reactant gas to porous gas diffusion layer. In this study, the block was installed on a simple fuel cell model. Using computational fluid dynamics (CFD), effects of forced convection due to blocks on a polarization curve and local current density contour were studied when different air flow rates were supplied. The high current density could be achieved even with low air supply rate due to forced convection to a gas diffusion layer and also with multiple blocks in series compared to a single block due to an increase of forced convection effect.