• Progress in Superconductivity
• /
• v.5 no.1
• /
• pp.21-25
• /
• 2003

We have designed and simulated an 1-bit ALU (Arithmetic Logic Unit) by using a half adder. An ALU is the part of a computer processor that carries out arithmetic and logic operations on the operands in computer instruction words. The designed ALU had limited operation functions of OR, AND, XOR, and ADD. It had a pipeline structure. We constructed an 1-bit ALU by using only one half adder and three control switches. We designed the control switches in two ways, dc switch and NDRO (Non Destructive Read Out) switch. We used dc switches because they were simple to use. NDRO pulse switches were used because they can be easily controlled by control signals of SET and RESET and show fast response time. The simulation results showed that designed circuits operate correctly and the circuit minimum margins were ＋/-27%. In this work, we used simulation tools of XIC and WRSPICE. The circuit layouts were also performed. The circuits are being fabricated.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1115-1119
• /
• 2007

Five control methods (Speed Control, PID Gain Scheduling, Loop Time Control, Simple PID, Switching Control) have been applied to the control of an Inline Co-axial valve by the simulation of AMESim. The simulation results have shown that the speed control method is the most stable and the fastest way to reach to the set point in the simulation of the flow control. Moreover, It has been found that the five control methods have the almost same characteristics in the power consumption, the counter electromotive force, and the motor angular velocity. According to the analysis results, the fast and stable control characteristics of the speed control method is the most suitable for the flow control using a inline co-axial valve with a DC(BLCD) motor.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.49 no.10
• /
• pp.502-508
• /
• 2000

This paper presents a dynamic simulation algorithm for studying the effect of United Power Flow Controller(UPFC) on the low frequency power system oscillations and transient stability studies. The proposed algorithm is a Newton-type one and uses current injection type UPFC model, which gives a fast convergence characteristics. The algorithm is applied to studying inter-area power oscillation damping enhancement of a sample two-area power system both in time domain and frequency domain. The case study results show that the proposed algorithm is very efficient and UPFC is very effective and robust against operating point change.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.6
• /
• pp.105-114
• /
• 1984

A fast pseudo-noise (PN) sequence acquisition algorithm for the direct-sequence (DS) spread spectrum system is proposed. The basic concept of the algorithm has been adopted from that of the classical sliding correlator. Mathematical modeling, analysis and computer simulation of the proposed system have been done. The results of analysis and computer simulation show that the acquisition system yields a significant performance improvement over the sliding correlator. Its acquisition time takes only 45 ms when signal-to-noise ratio(SNR) is -18dB. The algorithm developed has been implemented in hardware and its experimental result is also given.

• Electronics and Telecommunications Trends
• /
• v.35 no.4
• /
• pp.81-90
• /
• 2020

The use of machine learning technologies such as deep and reinforcement learning has proliferated in various domains with the advancement of deep neural network studies. To make the learning successful, both big data acquisition and fast processing are required. However, for some physical world applications such as autonomous drone flight, it is difficult to achieve efficient learning because learning with a premature A.I. is dangerous, cost-ineffective, and time-consuming. To solve these problems, simulation-based approaches can be considered. In this study, we analyze recent trends in drone simulation technologies and compare their features. Subsequently, we introduce Octopus, which is a highly precise and scalable drone simulator being developed by ETRI.

• Journal of the Korea Society for Simulation
• /
• v.9 no.1
• /
• pp.93-108
• /
• 2000

The stochastic manufacturing system has one or more random variables as inputs that lead to random outputs. Since the outputs are random, they can be considered only as estimates of the true characteristics of the system. These estimates could greatly differ from the corresponding real characteristics for the system. Multiple replications are necessary to get reliable information on the system and output data should be analyzed to get optimal solution. It requires too much computation time practically, In this paper a GA method, named Stochastic Genetic Algorithm(SGA) is proposed and tested to find the optimal solution fast and efficiently by reducing the number of replications.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.348-351
• /
• 2007

Simulations of the buckling behavior of a single wall carbon nanotube(SWCNT) was carried out using molecular dynamics simulation. Molecular dynamics simulations were done with 1fs of time step. Tersoff's potential function was used as the interatomic potential function since it has been proved to be reliable to describe the C-C bonds in carbon nanotubes. Compressive force was applied by moving the top end of the nanotube at a constant velocity. Buckling behavior under compressive load was observed for (15,15) armchair SWCNTs with 2nm of diameter and 24.9nm of length. Buckling load and critical strain is obtained from the MD simulation. Deformation occurred on the top region of the CNT because of fast downward velocity.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.3
• /
• pp.593-603
• /
• 1997

Connection admission decision in ATM networks requires decision made in real time using fast algorithm. It is difficult to construct a model of the multiplexed traffic and thus, approximation of the traffic load is necessary. In this paper, we propose a measurement-based dynamic CAC(Connection admission Control) in ATM(Asynchronous Transfer Mode) networks, which observes current traffic by the moving window and set the window size to the value which is computed from the measured cell loss amount. It is based on the measurements of the traffic load over an admission period that is load enough to reflect the current traffic behavior instead of analytic modeling. And, the dynamic reallocation of bandwidth for each class leads to effective bandwidth utilization. The performance of proposed method is analyzed through computer simulation. The performance of proposed method is analyzed by using SIMAN simulation package and FORTRAN language. As can be seen in the simulation result, cell loss performance and bandwidth utilization have been increased.

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.31-44
• /
• 2019

This study simulated a control rod assembly (CRA), which is a part of reactor shutdown systems, in immersed and fluid flow conditions. The CRA was inserted into the reactor core within a predetermined time limit under normal and abnormal operating conditions, and the CRA (which consists of complex geometric shapes) drop behavior is numerically modeled for simulation. A full-scale prototype CRA drop test is established under room temperature and water-fluid conditions for verification and validation. This paper describes the details of the numerical modeling and analysis results of the several conditions. Results from the developed numerical simulation code are compared with the test results to verify the numerical model and developed computer code. The developed code is in very good agreement with the test results and this numerical analysis model and method may replace the experimental and CFD method to predict the drop behavior of CRA.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.332-337
• /
• 2016

The rapid reconstruction of a transfer path is caused by frequent secession of nodes in many applications using overlay multicast. For this, however, many studies have been proposed, but a study of fast path recovery is required. This paper proposes a new method for fast path recovery to improve the path reconstruction time and for stable path maintain caused by the sudden secession of the parent node on overlay multicast. The proposed method uses the virtual transfer path and the candidate parent node for the fast path recovery. All nodes exchange periodically the RTT (Round Trip Time) information between the other nodes of similar position itself and neighboring node. All nodes have a candidate parent node list, and each node stores the exchanged RTT information on the list. Each node constructs the virtual transfer path to reduce the recovery time after deciding a candidate parent node that is one of them by the RTT order. In this way, when the parent node is seceded, all nodes can recover the transfer path quickly using the virtual transfer path. The simulation result showed that the recovery time of the proposed method is an average 30% faster than the known method.