• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.151-159
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• 2008

The parameter-based cardiovascular impedance simulator that is able to overcome the limits of conventional mock circulatory systems is critical for the development and test of biomedical devices including artificial heart. The concept of impedance simulator was validated mathematically in a previous study using high-gain feedback linearization control which, however, may cause serious difficulties and limits for practical implementation. In this study, therefore, practical applicability of the impedance simulator is investigated considering the physical limits such as motor speed and torque. Simple PID controller which do not require complex model of the simulator is used considering the practical implementation. Design guidelines of the impedance simulator are also provided based on the results.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.97-100
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• 2004

Steel encased composite columns are widely used due to their excellent structural performance in terms of stiffness, strength, and ductility. However, experimental studies were usually for the columns having higher steel ratio $(3-4\%)$. There are two different design concepts for SRC columns. ACI-318 specifies the design strength of the column using the same concept of reinforced concrete columns. AISC-LRFD specifies the P-M diagram using the concept of steel column. In this paper, SRC columns have the steel ratio of $0.53\%\;and\;1.06\%$. From the test results, ACI-318 specifications showed better evaluation of SRC columns having low steel ratio. H beam and steel tube partially filled with concrete were embedded in concrete. Flexural tests showed considerably high ductility.

• KIEE International Transactions on Power Engineering
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• v.3A no.2
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• pp.85-92
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• 2003

When a current transformer (CT) is saturated, the wave-shape of the secondary current is distorted and contains points of inflection, which correspond to the start or end of each saturation period. Discontinuity in the first-difference function of the current arises at points of inflection, where the second and third differences convert into pulses that can be used to detect saturation. This paper describes the design and evaluation of a CT saturation detection technique using the third-difference function and includes the countermeasure for a spike signal. Test results clearly demonstrate that the algorithm successfully detects the start and end of each saturation period irrespective of the remanent flux and magnetization inductance in the saturated region. This paper concludes by describing the results of hardware implementation of the algorithm using a DSP.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.5-10
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• 2006

The heavy thermal load to battle tanks can cause electronic components' malfunction and crew to be put out of action. The thermal load is generated from Internal heat sources such as electronic devices installed in the room as well as extremely hot weather. In this study, heat and flow analysis for the cabin room of a battle tank was performed to deal with this thermal problem. This study presented the validation of simulation results in comparison with those of test, the investigation of optimal flow design for effective cooling in cabin room and finally the evaluation of thermal comforts to crew.

• Nuclear Engineering and Technology
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• v.30 no.6
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• pp.592-608
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• 1998

Inspection of RCS flow measurements for the domestic pressurized water reactors has been performed by the Korea Institute of Nuclear Safety (KINS) as one of the authorized periodical inspection activities. The inspection results for the Westinghouse-type plants reveal that 1) the RCS flow instrumentation has been calibrated by using the initial design and commissioning test result, without reflecting the cycle specific reference flow measurements, 2) the loop-to-loop now variation in the actual flow measurement which has not been considered in the safety analysis affects the asymmetric How transient results, and 3) the measured RCS flows in Kori 3 and 4, Yonggwang 1 and 2 do not support the definition of the best estimate RCS flow, approaching the RCS flow limit. In this study, the revealed problems were discussed with review of the design and the RCS flow measurement uncertainty evaluation, and the technical approaches and recommendations for resolving these problems were proposed.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.649-655
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• 2019

Fracture behaviors of SCM435 high strength bolt have been studied including macroscopic and microscopic fracture observation, Energy Dispersive X-ray Spectroscopy, Vickers hardness test and applied stress evaluation. cracks (ratchet marks) were generated by the repetitive loads acting on the bolts, initial stress of bolt and the stress concentration. The applied stress was found to be slightly higher than the fatigue limit of the material. The initial stress of bolt must be removed, and the mold temperature during the process must be maintained by room temperature. Bolts are recommended to be peened to improve fatigue limit.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.353-363
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• 2023

The STELLA-2 is a large-scale sodium thermal-hydraulic integral effect test facility and supports the development of PGSFR. The facility adopted Pump Simulation Loop System (PSLS) concept for the mechanical sodium pump in the reference reactor to control and to measure the primary sodium flow. Since the component (mechanical pump) is replaced by the loop, it is very important to evaluate the similarity between the pump and the loop. In this paper, to simulate the characteristic of the mechanical sodium pump, the pressure loss along the various options of the loop was evaluated and the comprehensive validity of each design options was analyzed. Using the similarity criteria based on the Richardson number and Euler number conservation, the PSLS design was finalized and the result was within the acceptable error range. Finally, the result of this study was used for construction of the overall facility, STELLA-2.

• Journal of the Korea Society for Simulation
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• v.28 no.4
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• pp.33-43
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• 2019

Link-16 is a data link that provides joint interoperability to the US Navy, Air Force and NATO. Currently, the military relies entirely on foreign SW and tools for test environment, tactical simulation training and interoperability verification test for Link-16 operation. Therefore, it is necessary to develop Link-16 based operation environment test tool. In this paper, Link-16 network operational performance analysis simulator was developed by analyzing the function of Link-16 foreign tools. It also implements the SIMPLE standard interface for interworking with foreign SW and tools. The functional model for Link-16 network operation performance analysis consists of pre-analysis, real-time operational analysis, and post-analysis functional model. Each functional model test was performed through SIMPLE interworking with foreign SW and tools. Link-16 network operation performance analysis If we replace foreign SW through simulator, we can perform tactical training, network design verification and operation (scenario) verification for our military.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.697-707
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• 2004

Most bridge piers were practically designed and constructed with lap spliced longitudinal reinforcing steels before the 1992 seismic design provisions of Korea Bridge Design Specification were implemented. It has been known that lap splice of longitudinal reinforcement in the plastic hinge region is not desirable for seismic performance of RC bridge piers. The objective of this research is to evaluate the seismic performance of existing circular reinforced concrete bridge piers by the Quasi-static test and to propose the need of seismic retrofit of existing bridge piers through the damage level. Test specimens were nonseismically designed with the aspect ratio 4.0 which could induce the flexural failure mode. It was confirmed from this experiment that significant reduction of seismic performance was observed for test specimens with lap spliced longitudinal reinforcing steels. Pertinent seismic retrofit was determined to be needed for existing RC bridge piers with the lap-spliced of $50\%$ longitudinal reinforcing steels.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.180-189
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• 2017

Some people who take a driver's license test retake it again because of license cancellation, but most of them take the test for the first time to drive the car. Driving a car is directly linked to life, and the initial correct driving habits are more important than anything else. In particular, it is very important to obtain a license by evaluating the correct driving ability based on objective and fair standards when learning the first driving, because many people acquire a driving license while entering the society for the first time. In this paper, we propose the S / W design and its main functions that can emit high quality drivers through efficient, fair and accurate automated scoring. Through this, it is proposed to improve the automatic grading driver's license system, to prevent traffic accidents, and to reduce traffic accidents through proper driving.