• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.13-21
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• 2001

Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.65-66
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• 2006

The speciality of education installation has to be applied to the design construction, inspection of school in the installation. But. it was applied general electric installation standards in korea. Therefore, the electric shock accidents and fire was more frequently occurred in the school than in other building. So, this paper, is proposed the comprehensive countermeasure for safety of school electric installation

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.1
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• pp.98-107
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• 2017

Electric components equipped with naval shipboards must endure mechanical shock caused by various mechanical impulsive sources. Thus the components must be designed carefully and reliability test is an essential procedure before use. In this study, a new design technology applicable to a large and heavy shock generation system which can generate various specific real mechanical shocks in specified time domain was introduced. Commonly, the shock transmitted through the wall of naval shipboard consists of dual shocks. The primary shock is of a very high amplitude and very short period half-sine form. The following shock is of an exponentially decaying harmonic form of relatively longer period. Based on the different dynamic characteristics of two shocks, we proposed a sequential design procedure to determine spring and damping coefficients of the generation system. Some numerical simulation results showed the feasibility of the proposed method.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.961-965
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• 1992

It is well-known that shock waves frequently occur inside the nozzle of the interrupter, and that they play important roles in the arc interruption. A model interrupter with two-dimensional dual-airflow nozzles was used for this experiment. The arc was ignited with 1.4 mil copper wire stretched between the electrodes which were spaced out 56 mm. The arc current of 60 to 230 A was achieved by adjusting the external resistance from 5.5 to 1.6 ohms. The arc tests have been conducted for investigating the air arc characteristics, and the effects of shock waves and nozzle pressure ratios on the arc voltage, the arc resistance, the arc power, and average electric field. The results of these tests have been analyzed to provide insights into the arc characteristics for gas circuit breakers. The average electric field is represented by the function of the arc current to show the negative E-I characteristic explicitly. The effects of shock waves and nozzle pressure ratios are shown to be significant for a circuit breaker performance.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.612-618
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• 2012

In this paper, in order to prevent electric shock of high voltage system of HFCV after crash test, insulation performance measurement methods were studied. Under conditions of in-use, insulation performance tests can be divided into measurement method using the vehicle's own RESS as DC voltage source and measurement method using DC voltage from off-vehicle sources. However, these tests can not be applied after a post-crash because parts of high voltage system cover should be removed, and insulation performance can be influenced during these tests. Therefore, we proposed post-crash insulation performance test methods for preventing electric shock through problem analysis of previous post-crash insulation performance tests. Also, test equipment which can measure voltage absence and total energy was developed. We verified performance of the equipment through experiments with vehicle test.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.344-351
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• 1999

The safe operation of electro railways is greatly dependant on its protective systems. The system so-called Fault Protection Wire(FW) is now widely adapted to protect in AT feeding systems. It is connected between the feeder and trolley circuit to return the fault current to autotransfonmers at substation. This paper computed the distribution of fault currents at FW in the system and also evaluated the safety from electric shock when ground fault or flashover occur in the feeding system. The results show FW is useful to protect power supply network from fault in electric railways

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.189-193
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• 2007

The grounding of an electrical system is one of the essential elements for public safety. Domestic practice of grounding system design has been to get grounding resistance values which are classified by facilities or equipment in the regulations. But the concept of grounding system design of IEC is, as a main factor of safety index, to consider touch voltage and step voltage instead of the resistance value itself. Recently IEC actively develops or revises safety related standards which are essential for the grounding system performance. In this paper, we present the recent trend of the international standards on the safety criteria for Electric Shock Protection.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.4
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• pp.391-396
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• 1999

It is well known that fish hear a wide frequency range of sound using both laterial line and inner ear, and the sound is probably the most effective channel for long-range communication underwater than any other stimulus.The auditory threshold of svenband grouper, Epinephelus septem fasciatus was determined by conditioning method using a sound coupled with electric shock in a tank. The audio-signals and electric shock used in the experiment were pure tones of 100 to 1000Hz and DC 6n.The response of fish to the sound was observed by ECG intervals from precordial leads method (V1·V2 method). The auditory threshold curve for sevenband grouper was V-shaped, with most sensitive threshold at 350Hz in the range of 100~1000Hz. The Sevenband grouper were more sensitive to sounds of 200~400Hz than to adjacent frequencies.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.214-217
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• 2005

To improve the safety of facilities and human beings when the ground fault occurs, public power utility prescribes the reasonable ground resistances, measures and controls the ground resistance of all the ground electrodes biennially. Concerning the safety of human, there are two safety criteria widely accepted, i.e. the IEEE Std 80-2000 and the IEC 479-1:1994. The IEEE Std 80-2000 is based on a simplified electric shock model usually translated into permissible touch and step voltages. The IEC 479-1:1994 is less specific than IEEE Std 80-2000 for analysis purpose. The IEC 479-1:1994 provides values of permissible body current against electric shock duration. This paper provides a technical study of these two standards to analyze the safety of human beings of ground electrodes developed recently for distribution power system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.87-91
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• 1997

This paper presents the modeling and analysis of dynamic characteristics of hydraulic snubber in electric power plant. The nonlinear state equations of 9th order to describe the dynamics of the snubber was established by Sirnulink. The simulation results show that the hydraulic snubber reacts as like the conventional shock absolvers to the high pulse shock load. The snubber also shows the peculiar characteristics to the small step load, which are temporary locking displacements of control valves and same steady-state pressures of all internal chambers in the snubber.