• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.211-223
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• 2021

Purpose : The purpose of this study was to examine the effect of task-oriented circuit training using unstable support surface on balance, gait ability, and balance confidence in subacute stroke patients. Methods : Forty-five patients with subacute stroke were randomly divided into the three following groups of 15: 1) TOCT-US group; task-oriented circuit training using unstable surface (experimental group 1), 2) TOCT-SS group; task-oriented circuit training using stable surface (experimental group 2), and 3) CON group; conventional physical therapy (control group). All patients participated in one of the three training programs for 6 weeks, 30 minutes per session, 3 times per week. Patients' balance ability was assessed using the BT-4, BBS (berg balance scale), TUG (time up and go test), and LOS (limit of stability). Gait speed was measured to examine gait ability. K-ABC (activities-specific balance confidence scale) was also used to assess the level of patients' confidence in daily activities. Results : After the intervention, the sway area in experimental groups 1 and 2 decreased, but that in the control group increased. Experimental group 1 showed significant improvement compared with experimental group 2 and the control group. BBS, TUG, and LOS scores of experimental group 1 were significantly improved compared with those of experimental group 2 and the control group. Also, gait speed significantly improved in experimental group 1 compared with experimental group 2 and the control group. Experimental groups 1 and 2 showed significant improvement in K-ABC scores after training. Conclusion : Patients with subacute stroke had significantly improved balance, gait, and level of confidence in performing activities of daily living following task-oriented circuit training using the unstable surface. This indicates that task-oriented circuit training using unstable surfaces can be an effective treatment method for the recovery of balance and gait in subacute stroke patients.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.441-448
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• 2022

In the distribution system, there are multiple power protection systems such as circuit breakers at substations, and reclosers, minimum circuit ampacities, fault interrupters on distribution lines. They are widely used to prevent partial outages, cascading power failure or blackout so that other healthy systems could maintain the integrity in case of the instant fault or permanent failure on the power lines. However, when a fault happens, it could cause a major black out due to the lack of the protection cooperation between the protection relay of the circuit breaker at a substation and a protection system on the distribution lines. To achieve the power system integrity better, it is required to develop the circuit breaker which can be operational within 1 cycle(16ms). In this study, the high speed circuit breaker which is filled up with eco-friendly gas is developed. This equipment achieved an excellent test results based on IEC 62271-111 standard. It is respected that this equipment would contribute to prevent the wide area blackout by isolating a fault area quicker and faster.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.617-624
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• 2023

Recently, miniaturization and low power consumption of electronic products and improved efficiency and power factor improvement have become a matter of great interest. In this paper, an AC-DC converter based on PWM control was designed and made. The AC-DC converter is designed with a structure in which one rectifier circuit and one output voltage control circuit are connected in series. The rectifier circuit is a diode-based single phase full-wave current circuit and the output voltage control circuit is a DC-DC conversion circuit based on PWM control. Arduino was used as the main control device for PWM control, and LCD was configured at the output stage so that the control result could be checked. The error between the output voltage displayed on the oscilloscope and LCD and the target output voltage was confirmed through repeated experiments with the test circuit, and the validity of the proposed design methodology was confirmed by showing an error rate of about 5% based on the oscilloscope measurement value.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.87-95
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• 2008

In this paper, we developed a selectable observation Point test architecture and test procedure for clocked 4-bit synchronous counter circuit based on boundary scan architecture. To develope, we analyze the operation of Sample/Preload instruction on boundary scan architecture. The Sample/Preload instruction make Possible to snapshot of outputs of CUT(circuit under test) at the specific time. But the changes of output of CUT during normal operation are not possible to observe using Sample/Preload in typical scan architecture. We suggested a selectable observation point test architecture that allows to select output of CUT and to observe of the changes of selected output of CUT during normal operation. The suggested a selectable observation point test architecture and test procedure is simulated by Altera Max 10.0. The simulation results of 4-bit counter shows the accurate operation and effectiveness of the proposed test architecture and procedure.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1359-1361
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• 1995

This paper describes the method of diagnosis for power transformer, using vibration signal analysis. Vibration signal to be made from transformer is the liner combination of load current, applied voltage and internal temperature. This study measured the vibration signal by before and after short circuit test of the transformer. And the signal analysis and comparison was carried out for AR modeling and frequency analysis.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.941-942
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• 2011

A thermal equivalent circuit of IPMSM considering eddy current loss of PM and core loss of rotor is proposed. This thermal equivalent model is represented by the thermal resistances and thermal capacitances. In order to determine the factor of each parameter, a heating test is processed. Additionally, the eddy current loss of PM is calculated by a transient 3D finite element analysis. Finally, this thermal equivalent model is verified by a temperature test in a 25kW 12-pole/18-slot IPMSM with varying load.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.139-142
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• 2001

As microeletronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important for many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (5-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.717-719
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• 2001

This paper deals with simulation of the three-phase dc reactor type fault current limiter(FCL). This is a preliminary step to develop the FCL's faculties for an application to high voltage transmission line. A three-phase dc reactor type FCL consists of transformers, diodes, and a superconducting coil. By this simulation for the short-circuit test we can investigate the safety of FCL's elements. And, result of simulation will contribute parameter toward optimal design.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.17-20
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• 2005

We has designed, fabricated, and measured a Single flux quantum (SFQ) toggle flip-flop (TFF). The TFF is widely used in superconductive digital electronics circuits. Many digital devices, such as frequency counter, counting ADC and program counter be used TFF Specially, a program counter may be constructed based on TFF We have designed the newly TFF and obtained high bias margins on test. In this work, we used two circuit simulation tools, WRspice and Julia, as circuit optimization tools. We used XIC for a layout tool. Newly designed TFF had minimum bias margins of +/- $37\%$ and maximum bias margins of +/-$37\%$(enhanced from +/- $37\%$). The designed circuits were fabricated by using Nb technology The test results showed that the re-optimized TFF operated correctly on 100kHz and had a very wide bias margins of +/- $53\%$.