• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.550-553
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• 2002

A source meter is a basic instrument to perform a measurement of DC characteristic of semiconductor devices. the source meter can be used as variable voltage source, variable current source, voltage meter, or current meter. The accuracy of the low current measurement can be improved with the compensation of leakage current and charge and discharge current. In the low current measurement, the RC time constant is extremely big, so the measurement speed is very low. In this thesis, the analysis of the behavior of the measurement current according to the RC time constant and output capacitance and the method to accelerate the measurement speed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.49-55
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• 2002

A new method is proposed for the on-line measurement of the fiber orientation of sheet materials. The measurement of fiber orientation is very important in manufacturing paper sheets, non-woven fabrics, and glass sheets, because fiber orientation strongly affects product properties represented by, for example, dimensional stability of paper. A method developed in this research utilizes anisotropy of dielectric constants of sheet materials as a key characteristic to determine the fiber orientation. The new on-line sensor, consisting of 5 microwave dielectric resonators set in different directions, was designed to detect the fiber orientation while paper is running with high speed on a paper machine. This sensor can determine the direction and the degree of fiber orientation from the measured direction of the maximal dielectric constant and its variation, respectively. The fundamental performance of this system was examined by the static measurement of printing grade paper, which gave a satisfactory result. Then, the dynamic measurements were done at a speed of 1,000 m/min by using a high-speed test-coating machine.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2C
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• pp.119-125
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• 2011

Start This paper analyzes the propagation characteristics of acoustic signals in indoor environments, which is applicable to indoor positioning system. Indoor stereo sound system is generally valid within $25m^2$. So it is not possible to apply prevalent sound propagation characteristic to indoor positioning system because the prevalent acoustic signals propagation characteristic is defined under free space condition. Therefore, in this paper, we present the propagation characteristics of acoustic signals in indoor environments considering the free space propagation characteristic as well as room characteristic such as humidity, temperature, absorption of atmosphere and so on. To verify the designed propagation model of indoor acoustic signals, this paper presents the propagation characteristics of decreasing sinusoidal signals whose frequencies ate from 1kHz to 20kHz in anechoic room. In addition, this paper also presents the propagation characteristics of decreasing sinusoidal signals which have multiple frequencies.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.1-5
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• 2009

NiTiCu alloys can produce a large force per unit volume and operate with a simple mechanism. For this reasons, it has been widely studied for application as a micro actuator. So in this study, one-way and two way shape memory effects of Ti-42.5at%Ni-2.0at%Cu alloys are studied. In the case of one-way shape memory effects, shape memory recoverable stress and strain of this alloys were measured by means of tension and compression tests under constant temperature. The strains by tension and compression stress were perfectly recovered by heating at any testing conditions also shape memory recoverable stress increased to 116 MPa in tension tests and to 260 MPa in compression tests. In the case of two-way shape memory effects, transformation temperatures from thermal cycling under constant uniaxial applied tension and compression loads linearly increased by increasing external loads and their maximum recoverable strain is 3.8% at 100MPa tensile condition and 2.2% at 125 MPa compression condition.

• Proceedings of the KIEE Conference
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• summer
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• pp.1223-1225
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• 2004

In difference with the rotary type electrical machinery, the linear induction motor(LIM) that generates the direct thrust directly, is widely used for the operation system of electrified railroad, elevation system, conveyer system, and so on. The operational principle of linear induction motor is constructively similar to the general rotary induction motor. It is difficult to realize the complicate linear induction motor which is applied SVPWM system, but widely used in vector motor control system or servo control system because of its high performance in current control. In this paper, we presented the dynamic characteristic analyzing methode, and calculated efficiently the end effect by using equivalent circuit methode in the operating linear induction motor control system for Maltlab simulink modeling.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.647-650
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• 2004

The modeling of an active vibration isolation system is accomplished by using the equivalent spring constant, mass and rotational Inertia of each component. The detailed model of the actuation module is successful for describing its frequency-domain performance but also too complicated to implement it to actual system for control so that the order of the model is reduced up to the degree that preserves its characteristic in the low frequency range. The reduced model is suitable for identifying the unknown system parameters such as damping constants of components. The overall isolation system is described by using the reduced model of the actuation module. The accurate model ing and system parameter identification that is essential for the control of the active vibration isolation system is attained successfully.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1157-1165
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• 2000

A classic examples of the abnormal combustions are the knock and misfire, which raise noxious performance and life of the engine. A heavy knock can also cause severe damages to the engine itself, which gives more reason why it must be detected and corrected. With the response of the today's requirements, we have researched the new diagnostic system which uses the breakdown voltage characteristics between electrodes of spark plug. This breakdown voltage depends on the pressure, temperature and even the shape and material of electrodes. But there is no data of breakdown voltage in case of using the spark plug as a electrodes. So, in this study, we show the breakdown voltage characteristic by pressure and temperature in constant volume bomb, which will make it possible to diagnose the engine combustion phenomenon.

• Fire Science and Engineering
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• v.9 no.1
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• pp.20-29
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• 1995

The sprinkler head is a component of the sprinkler system intended to discharge water for automatic detection and extinguishment of fires. On this study, thermal characteristic values affecting the sensitivity of the fusible alloy type sprinkler head were obtained and analyzed under heated air stream condition which had constant temperature and velocity. The experiment was carried out under the forced convection condition with both the conductive heat loss considered and neglected. The thermal characteristic values of the sprinkler head were obtained in accordance with the material and shape of the heat responsive element and the conditions of the main body.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.228-231
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• 2006

In general, burning time is not considered with a factor of an empirical relation on the combustion characteristic in hybrid propulsion system. So, The effect of burning time on hybrid combustion characteristics and propulsion characteristics was studied. As results, regression rate is decrease with burning time, but fuel mass flux is maintained nearly constant with burning time at given oxidizer mass flux.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.37-42
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• 1997

Off-line feed rate scheduling is an advanced methodology to automatically determine optimum feed rates for the optimization of NC code. However, the present feed rate scheduling systems have lim~tations to generate the optimized NC codes because they use the material removal rate or non-generalized cutting force model. In this paper, a feed rate scheduling system based on an improved cutting force model that can predrct cutting forces exactly in general machining was presented. Original blocks of NC code were divided to small ones with the modified feed rates to adjust the peak value of cutting forces to a constant vale. The characteristic of acceleration and deceleration for a given machrne tool was considered when off-line feed rate scheduhng was performed. Software for the NC code optimization was developed and applied to pocket machining simulation.