• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.2
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• pp.33-43
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• 1993

Lock mechanism is essential for synchronization on the multiprocessor systems. Lock mechanism needs to reduce the time for lock operation in low lock contention. Lock mechanism must consider the case of the high lock contention. The conventional lock control scheme in memory results in the increase of bus traffic and memory utilization in lock operation. This paper suggests a lock scheme which stores the lock data in cache and manages it efficiently to reduce the time spent in lock operation when the lock contention is low on a multiprocessor system built on HiPi-bus(Highly Pipelined bus). This paper also presents the design of the HIPi-CLOCK (Highly Pipelined bus Cache LOCK mechanism) which transfere the data from on cache to another when the lock contention is high. The designed simulator compares the conventional lock scheme which controls the lock in memory with the suggested HiPi-CLOCK scheme in terms of the RMW(Read-Modify-Write) operation time using simulated trace. It is shown that the suggested lock control scheme performance is over twice than that of the conventional method in low lock contention. When the lock contention is high, the performance of the suggested scheme increases as the number of the shared lock data increases.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.125-139
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• 2017

Recently, interest in improving the quality of EMS(emergency medical services) has been increasing. Much effort is being made to innovate the EMS process. The rapid progress of ICT technology has accelerated the automation or intelligence of EMS processes. This study suggests an emergency room management method based on real-time data considering resource utilization optimization, minimization of human error and enhancement of predictability of medical care. Emergency room operation indices - Emergency care index, Short stay index, Human error inducing index, Waiting patience index - are developed. And emergency room operation rules based on these indices are presented. Simulation was performed on a virtual emergency room to verify the effectiveness of the proposed operating rule. Simulation results showed excellent performance in terms of length of stay.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.3
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• pp.355-363
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• 2007

This paper presents a method of an automatic work time evaluation based on the verification of a disassemblability and assembly configuration. Even though a work time evaluation is an important field of concern for planning assembly lay-out, there are some limitations using cumbersome user query or approximated work time data without considering assembly condition. To overcome such restriction, this paper presents a method to mathematically verify assembly conditions based on the disassemblability, which is defined by the separability and stability cost. The separability cost represents a facility of the part disassembly operation, and the stability cost which represents a degree of the stability for the base assembly motion. Based upon the results, we propose a new approach of evaluating work time using neural networks. The proposed method provides an effective means of solving the work time evaluation problem and gives a design guidance of planning assembly lay-out in flexible manufacturing application. Example study is given to illustrate the concepts and procedure of the proposed schemes.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.609-615
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• 1987

The optimal operation of power system is developed by alternately using real power dispatch and reactive power dispatch problem. The real power system scheduling process is formulated as an optimization problem with linear inequality constraints. A.C. loadflow method is used for the problem solution and line losses are considered. The constraints under consideration are generator power limits, load scehdling limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time application. The reactive power control problem uses the Dual Simplex Relaxation method as in the real scheduling case. Insted of minimizing the cost of power system, the objective is selected as to determine the highest possible voltage schedule. The constraints under consideration are the voltage limits at each node and the possibilities of supply or absobtion of reactive energy by generator units and the compensation facilities. Tests indicate that the method is practical for real time applications. The overall optimization methods developed in this paper proved to obtained fine results in minimizing object function compared with the method without using voltage control. And the overall voltage profiles were also improved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.1
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• pp.34-44
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• 1997

This study presents the recursive constraint bounding(RCB) method to reduce the cycle time in internal cylindrical plunge grinding process. This method can cope with process noise as well as modeling bias. The main features of RCB method are its utilization of measurements at the end of each cycle and its use of monotonicity analysis for determining the extremes of bias and noise. This method is investigated in simulation and evaluated by experiment in internal cylindrical plunge grinding operation. The results from simulation and experiment show that it is effective in reducing cycle time in spite of modeling uncertainty in the forms of process noise and modeling bias.

• Journal of Chest Surgery
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• v.32 no.10
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• pp.930-934
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• 1999

Background: The purpose of this study is to analyze the clinical results ad operative compatability by Ravitch methods with pectus excavatum. Material and Method: From 1984 to 1997, were performed Ravitch operations in 40 patients of pectus excavatum and analyzed the effects of correction and postoperative complication according to time of operation retrospectively. The group comprised 35 mem and women whose mean age was 8.9$\pm$7.9 years(between 2 to 35 years). All patients had corrected with Ravitch operation or its modified operation. Modified fixations were accomplished with K-wire in 15 patients and internal plate in 2 and the materials were removed 3 months after operation. The result of correction was estimated with the degree of changed distance between inner surface of sternal body and vertebral in 3 months after correction. Result: Postoperative complications were wound disruption in 14 patients. Estimated distances after correction ranged 0.4 cm to 4 cm. The acceptability for chest wall correction was high(6 excellent, 29 good in criteria of Humphreys). Conclusion: We concluded that the benefits of Ravitch operation were a high acceptability of patients and their family, and sufficient correction with no specific complications related operation.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.79-83
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• 2004

A new small signal stability analysis method for eigenvalue analysis is presented. This method utilizes the Resistive Companion Form (RCF) for the computation of the transition matrix over a specified time interval, which corresponds to a single cycle operation of the system. This method is applicable to any system, with or without switching element. An illustrative example of the method is presented and the eigenvalues are compared with those of the conventional state space method (analog) in order to demonstrate the accuracy of the proposed eigenvalue analysis method. Also, the variations of oscillation modes that are caused by the switching operation can be precisely analyzed using this method.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.594-599
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• 2003

This paper proposed to compare and analyze the data throughput of ALOHA and Slotted-ALOHA method which were used to the communication of satellites in an early stage and apply to the data throughput of a transponder in an RFID system. The ALOHA method is the operation priority to a transponder but the Slotted ALOHA method is the operation priority to an reader in an RFID system. Because ALOHA method transmits the data to an reader as a authority of a transponder at random time when generating collisions, therefore, it seems reasonable to conclude that ALOHA method is inefficient for the data throughput and the efficiency of collision interval than Slotted-ALOHA method that synchronizes and controls the transponder in an reader.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.515-521
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• 2020

Recently, data traffic has exploded due to development of various industries, which causes problems about losing of efficiency and overloaded existing networks. To solve these problems, network slicing, which uses a virtualization technology and provides a network optimized for various services, has received a lot of attention. In this paper, we propose a resource allocation method using credit value. In the method using the clustering technology, an operation for selecting a cluster is performed whenever an allocation request for various services occurs. On the other hand, in the proposed method, the credit value is set by using the residual capacity and balancing so that the slice request can be processed without performing the operation required for cluster selection. To prove proposed method, we perform processing time and balancing simulation. As a result, the processing time and the error factor of the proposed method are reduced by about 13.72% and about 7.96% compared with the clustering method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.398-402
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• 2008

Recently, the development of superconducting fault current limiters (SFCLs) has been required as power demands increase in the power system. A distribution-level prototype resistive SFCL using coated conductor (CC) has been developed by Hyundai Heavy Industries Co., Ltd. and Yonsei University for the first time in the world. The ratings of the SFCL are 13.2kV/630A at normal operating condition. A novel non-inductive winding method is used in fabricating coils so there is almost zero impedance during normal operation. The distribution SFCL is cooled by sub-cooled liquid nitrogen $(LN_2)$ of 65K and 3 bar to enhance cryo-dielectric performance, critical current density, and thermal conductivity. In order to make reliable operation of an SFCL in real power systems, we monitored and controled its operation conditions by using supervisory control and data acquisition (SCADA) method. Thus, a monitoring system for the SFCL employing information technology (IT) is proposed and developed to be on the lookout for the operation conditions such as inside temperature, inside pressure, $LN_2$ level, voltage and current. Since operation temperature should be kept constant, bang-bang control for temperature feedback with a heater attached to the cold head of cryo-cooler is applied to the system. Short-circuit tests with prospective fault current of 10kA and AC dielectric withstand voltage tests up to 143kV for 1 minute were successfully performed at Korea Electrotechnology Research Institute. This paper deals with the development of a distribution level SFCL and its monitoring system for reliable operation.