• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.10
• /
• pp.512-519
• /
• 2005

E-BLP security model considers the reliability of the processes that are real subjects in systems. This paper deals with the implementation of the E-BLP model for secure embedded systems. Implemented EBSM(E-BLP Based Security Module) consists of three components: identification and authentication, access control and BRC(Dynamic Reliability Check) that checks the process behavior dynamically. Access Control of EBSM ensures unreliable processes not to access the sensitive objects and the DRC detects the buffer overflow attack by normal user. Besides, the performance overhead of the embedded system applying the EBSM is introduced.

• The KIPS Transactions:PartC
• /
• v.12C no.1 s.97
• /
• pp.121-128
• /
• 2005

Tho existing TCP(Transmission Control Protocol) is known to be unsuitable for a network with the characteristics of high RDP(Bandwidth-Delay Product) because of the fixed small or large buffer size at the TCP sender and receiver. Thus, some trial cases of adjusting the buffer sizes automatically with respect to network condition have been proposed to improve the end-to-end TCP throughput. ATBT(Automatic TCP fluffer Tuning) attempts to assure the buffer size of TCP sender according to its current congestion window size but the ATBT assumes that the buffer size of TCP receiver is maximum value that operating system defines. In DRS(Dynamic Right Sizing), by estimating the TCP arrival data of two times the amount TCP data received previously, the TCP receiver simply reserves the buffer size for the next arrival, accordingly. However, we do not need to reserve exactly two times of buffer size because of the possibility of TCP segment loss. We propose an efficient TCP buffer tuning technique(called TBT-PLR: TCP buffer tuning algorithm based on packet loss ratio) since we adopt the ATBT mechanism and the TBT-PLR mechanism for the TCP sender and the TCP receiver, respectively. For the purpose of testing the actual TCP performance, we implemented our TBT-PLR by modifying the linux kernel version 2.4.18 and evaluated the TCP performance by comparing TBT-PLR with the TCP schemes of the fixed buffer size. As a result, more balanced usage among TCP connections was obtained.

• Journal of Digital Contents Society
• /
• v.2 no.2
• /
• pp.129-138
• /
• 2001

With the explosive growth and pervasive of the Internet, dynamic bandwidth allocation is nessary for ATM streams that carry various traffic. In order to provide quality of service(QoS) guarantees and to give the minimum cell rate, new bandwidth allocation scheme requires to be implemented. DFBA(Differential Fair Buffer Allocation) scheme is one of the methods for ATM GFR(Guaranteed Frame Rate) services. DFBA scheme treats cells selectively in a region between low buffer occupancy threshold and high buffer occupancy threshold. A big unbalance is introduced when the value being selected by DFBA scheme is greater than minimum rate. In a try to reduce the unbalance modified DFBA scheme is proposed. Selecting parameter according to the situation of network, this scheme is very effective to control the bandwidth in the various network situation.

• The KIPS Transactions:PartC
• /
• v.10C no.3
• /
• pp.305-310
• /
• 2003

The performance of various GFR implementations has been recently studied due to the interest to provide bandwidth guarantees with a simpler implementation than ABR in ATM networks. One of the important factors is buffer management for guaranteeing QoS in GFR service. An efficient buffer management algorithm is necessary to guarantee MCR for untagged cell in ATM switch. In this paper, we propose and evaluate a buffer management scheme to provide the GFR service guarantees. The proposed scheme can control the cell discarding for fairness in each VC, and compared with Double-EPD and DFBA. Our results show that the proposed buffer management with per-VC queuing achieves significant enhancement on goodputs and fairness index than those of existing methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.174-177
• /
• 2001

We have seen the effects of buffer layer in organic light-emitting diodes using poly(N-vinylcarbazole)(PVK). Polymer PVK buffer layer was made using spin casting techniques. Two different types of spin casting have been applied; static coating and dynamic coating. Two device structures were fabricated; one is ITO/TPD/Alq$_3$/Al as a reference, and the other is ITO/PVK/TPD/Alq$_3$/Al to see the effects of buffer layer in organic light-emitting diodes. Current-voltage characteristics and luminous efficiency were measured with a variation of spin-casting methods and rpm speeds. We have obtained an improvement of luminous efficiency by a factor of two and half when the PVK buffer layer is used.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.6
• /
• pp.28-36
• /
• 1998

We have proposed a new non-inverting SOI buffer circuit for the high speed operation at low supply voltage. The body biases of main MOS devices in the proposed circuit are controlled dynamically via subsidiary MOS device connected efficiently to the body terminal. We showed current derivability of the body controlled devices obtained by device simulation and compared with that of conventional SOI devices. Delay time characteristics of the buffer circuit were analyzed by SPICE simulation and compared with those of conventional SOI CMOS buffer circuits. Delay time reduction of the SOI buffer over conventional SOI CMOS buffer with same area is about 36 % at $V_{S}$=1.2 V and $C_{L}$=2 pF. pF.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.3
• /
• pp.61-68
• /
• 1983

In this paper various aspects of statistical maltiplexing of data signs have been investigated. A queueing model with finite waiting room and batch poisson arrivals is studied assuming that data signals are transmitted at a constant rate. Using traffic intensity and average burst length as parameters, overflow probabilities and expected queueing delay due to buffering are obtained. Also, a real system model of a statistical multiplexer that can be directly used in micro-programmed hardware realization is proposed. To examine the performance of the system, computer simulation has been done at various conditions. The results obtained can be used in designing a buffer efficiently.

• Journal of the Society of Naval Architects of Korea
• /
• v.39 no.3
• /
• pp.57-63
• /
• 2002

This paper describes a control algorithm for the buffer of a deep-sea mining system, in which the buffer is connected to a long slender pipe and then to a surface ship on one end, and to a collector on sea floor through a flexible hose on the other end. A mathematical modeling is established for designing the controller for buffer thrusters, in which the dynamic response of the long pipe is taken into account based on the mode superposition method. The fluid loading acting on the pipe is estimated by using Morison's formula. For simplicity, the surface ship is assumed to be kept stationary, the reaction from the flexible hose is ignored and only the lateral motions are considered. In order to guide the buffer to react only to the low-frequency motion of the surface vessel, the FIR digital filter is introduced to a PID-based controller It can be shown numerically that the high frequency component of the ship's motion can be effectively filtered out by using the FIR low pass filter.

• KDI Journal of Economic Policy
• /
• v.34 no.4
• /
• pp.69-90
• /
• 2012

This paper explores the effect of the countercyclical capital buffer using a DSGE (Dynamic Stochastic General Equilibrium) model with a banking sector. The main results are following. First, if the CAR (capital asset ratio) rises by 1%p as the countercyclical capital buffer, output and credit would increase less than otherwise by 0.8%p and 1.2%p, respectively. Second, the countercyclical capital buffer would decrease both credit and debt of banks, or deposit, and, as a result, boost the CAR. However, if we are going to use monetary policy to control credit expansion by allowing the interest rate to respond to credit, bank capital would also diminish, which would cause the CAR to be lower.

• Journal of the Korean Society of Safety
• /
• v.31 no.1
• /
• pp.33-40
• /
• 2016

Coupling systems under train's collision should take the impact by absorbing the impact energy caused from the collision, so the systems are very important parts for the safety of the trains. However, it is not easy to evaluate the performance of the system because it requires a huge testing facility, which is able to control the impact and to handle many safety issues. In this paper, test results are provided, which are obtained from collision tests of a single train having a coupling system in the front, and the results are analyzed in order to understand the characteristics and the dynamic behaviors of energy absorbing materials in the coupling system, such as a hydraulic buffer, and two rubber buffers. The results show that the force of each component could be empirically described by the compression displacement and velocity. The analyzed results will be applied to simulation models, and advanced studies wouuld be available if the simulation models are well validated with the test results.