• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.211-214
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• 2005

There are emerging many eScience applications. More and more scientists want to collaborate on their investigation with international partners without space limitation by using these applications. Since these applications have to analyze the massive raw data, scientists need to send and receive the data in short time. So today's network related requirement is high speed networking. The key point of network performance is transport protocol. We can use TCP and UDP as transport protocol but we use TCP due to the data reliability. However, TCP was designed under low bandwidth network, therefore, general TCP, for example Reno, cannot utilize the whole bandwidth of high capacity network. There are several TCP variants to solve TCP problems related to high speed networking. They can be classified into two groups: loss based TCP and delay based TCP. In this paper, I will compare two approaches of TCP variants and propose a hybrid approach for high speed networking.

• Explosives and Blasting
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• v.13 no.4
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• pp.5-27
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• 1995

Korea-America tungsten treaty is not only Earnning Us Dollar but also it was turnning point of tunnelling technology development such as a burn cut. Because 10th of specialist worked at Sangdong mine under treaty. The first of all, Experimental blasting pattern for single free face carried out. As a result it has brought the burden and $charge/m^3$ and also space distance. After the center holes are blasted. Remain of the works was the implementation of bench cut against the openning to make the full sectional are required. $Ca=\frac{A}{SW}$ where as A =ndi=m activated area S = Peripheral length of Charged room Ca = Rock Coefficient di=Holes diameter Later in 1980, The Oynaite Explosive is Replaced into Emulsion & Milli-Second Delay Electric Cap. Seqential Blasting machine were Applied in the Site. The Subway Tunnelling have been worked so Carefully for Vibration and Noise to near Shopping and housing area. We carried out Empirical formula to solve city Envoirement pollution as follow For Granite: $V=KW^{0.57}D^{-1.75}$ For Granite : $V=KW^{0.5}D^{-1.5}$ V=PPV(cm/sec) K=Coefficency D=Distance(m) W=Amount of power/delay(kg)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.283-288
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• 2005

Packet transmission and independent addressing in the mobile environments are very similar to the ones in the multicasting environment. So, in this paper, we propose a new scheme about how to manage the multicasting group and to set the communication path in the mobile environment by applying two-level addressing mode, which is similar to mobile If, for location-independent address setting. And we propose the smooth handoff scheme that minimizes the handoff delay for mobile multimedia services. To check the performance of our proposed scheme, we modified the NS-2 network simulator and as a result, we showed that our proposed scheme is better than other techniques in terms of handoff delay and transmitted packets' throughput.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.12
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• pp.575-583
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• 2001

It is hard to obtain good robust performance and robust stability for uncertain and time-varying system. The robust 2-DOF controller is frequently used to obtain the desired response and the good robustness. Two controllers can be independently designed. Generally, one controller reduces sensitivity to parameter variations, nonlinear effects, and other disturbances. On the other hand, the other controller reduces the error between the desired command and output. In this paper, the various robust perfect MFCs(model-following controllers) combined with TDC(Time Delay Control) are designed, and the imperfect stable MFC combined with TDC and SMC(Sliding Mode Control) is proposed. These controllers are based on the method of designing robust 2-DOF controllers for dynamic system with uncertainty. The performance of the proposed imperfect sable MFC has been evaluated through computer simulations. The simulation results indicate that the proposed controller shows the excellent performance characteristics for an overhead crane with uncertain and time-varying parameters.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.3
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• pp.1-10
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• 1997

We present an approach to high-level synthesis for a specific target architecture-partitioned bus architecture. In this approach, we have specific goals of minimizing data transfer length and number of buses in addition to common synthesis goals such as minimizing number of control steps and satisfying given resource constraint. Minimizing data transfer length and number of buses can be very important design goals in the era of deep submicron technology in which interconnection delay and area dominate total delay and area of the chip to be designed. in partitioned bus architecture, to get optimal solution satisfying all the goals, partitioning of operation nodes among segments and ordering of segments as well as scheduling and allocation/binding must be considered concurrently. Those additional goals may impose much more complexity on the existing high-level synthesis problem. To cope with this increased complexity and get reasonable results, we have employed two ideas in ur synthesis approach-extension of the target architecture to alleviate bus requirement for data transfer and adoption of genetic algorithm as a principal methodology for design space exploration. Experimental results show that our approach is a promising high-level synthesis mehtodology for partitioned bus architecture.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.115-122
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• 2000

In design of a digital current controller for a 3cP PWM converter, its conventional model is used in obtaining i its discretized version. But, it has errors since the characteristics of SVPWM and time delay are not taken i into consideration. In this paper, the new reference frame model of a 3c~ PWJVI converter is proposed C considering these problems. Also, the direct digital current controller based on this model is designed without a any extra algolithm. A simple tuning algorithm for the proposed current controller is given to compensate the i inductaηce mismatch problem. Then simulation and experimental results show the validity of the algolithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.303-311
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• 2011

In this paper, we propose the adaptive multibeamforming algorithm to remove the same subcarrier interference and multipath signals in the MIMO(Multi-Input Multi-Out)-OFDMA (Orthogonal Frequency Division Multiplexing Access)system allocated the same subcarrier partially in order to improve spectrum efficiency. In addition to removing the interference, we can get diversity gain and combat the detriment of the performance according to time delay by the proposed approach. BER performance improvement and combating the delay spread detrimental effects of the proposed approach is investigated through computer simulation by applying it to MIMO-OFDMA.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2018-2020
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• 1998

In design of a digital current controller for a 3$\phi$ voltage-source (VS) PWM converter, its conventional model, i.e., stationary or synchronous reference frame model, is used in obtaining its discretized version. It introduces, however, inherent errors since the following practical problems are not taken into consideration: the characteristics of the space vector-based pulsewidth modulation (SVPWM) and the time delays in the process of sampling and computation. In this paper, the new hybrid reference frame model of the 3$\phi$ VS PWM converter is proposed considering these problems. In addition, the direct digital current controller based on this model is designed without any prediction or extrapolation algorithm to compensate the time delay. So the control algorithm is made very simple. The validity of the proposed algorithm is proved by the computer simulation results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.849-850
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• 2006

This thesis presents a new analysis method of Vegas network model in single link single source and a new version of Vegas for expanding asymptotically stable region. Actually since original Vegas model is difficult to analysis, we use a modified Vegas network model. Since there is a few tools to analyze nonlinear system with delay, developing other methods is very important and useful. We used state space model in discrete time. Using by Jury's criterion, we could find asymptotically stable region of Vegas network model. And it was a if and only if condition. Moreover, we proposed a new version of Vegas algorithm. To expand asymptotically stable region we modified the original Vegas model. The new analysis method and new Vegas algorithm were justified by ns-2 simulation. And as compare with other result, we could know our method has many advantages.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1573-1595
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• 2011

In this paper, the outage performance of multiuser multiple-input single-output (MISO) systems exploiting joint spatial and multiuser diversities is investigated for Rayleigh fading channels with outdated feedback. First, we derive closed-form exact outage probabilities for the joint diversity schemes that combine user scheduling with different spatial diversity techniques, including: 1) transmit maximum-ratio combining (TMRC); 2) transmit antenna selection (TAS); and 3) orthogonal space-time block coding (OSTBC). Then the asymptotic outage probabilities are analyzed to gain more insights into the effect of feedback delay. It is observed that with outdated feedback, the asymptotic diversity order of the multiuser OSTBC (M-OSTBC) scheme is equal to the number of transmit antennas at the base station, while that of the multiuser TMRC (M-TMRC) and the multiuser TAS (M-TAS) schemes reduce to one. Further by comparing the asymptotic outage probabilities, it is found that the M-TMRC scheme outperforms the M-TAS scheme, and the M-OSTBC scheme can perform best in the outage regime of practical interest when the feedback delay is large. Theoretical analysis is verified by simulation results.