• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.51-55
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• 2023

Measurement of the ferroelectric polarization hysteresis curve is an important means of overall evaluation and interpretation of the ferroelectric structure and dielectric properties. If a resistive component is included in the ferroelectric sample, an error is included in the measured value of the spontaneous polarization. When configuring the electrical circuit to measure the polarization, by properly utilizing the external resistance corresponding to the resistive component included in the sample, the error due to the resistive loss of the sample was excluded and the size of the ferroelectric polarization induced inside could be accurately measured. It is expected that the displacement and dielectric characteristics of ions inside the ferroelectric can be more accurately evaluated through the evaluation of such an accurate polarization hysteresis curve.

• Korean journal of applied entomology
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• v.32 no.3
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• pp.323-329
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• 1993

These studies were conducted to evaluate the five comparative test methods for detecting chemical resistance and to investigate resistant level of field populations of diamondback moth (Plutella xylostella L.). Leaf disc method was practically rocomrnendable because of its rapidity and low CV(l1.4%). Topical application method was a precise replicabiliLy(CV=8.00/0) but it was time consuming and difficult in mampulation. The other 3 methods showed higher CV ranging from 14.9% to 21.4%. Based on $LC_{50}$ values by topical application method, field populations of diamondback moth collected from 4 different regions, Kwangju, Kimhae, Jeju, and Inje to prothiofos showed from 3.3 to 61.1 times higher resistance than the susceptible strain, whereas to cypermethrin, Lhey were from 7.5 to 141.7 times higher than the susceptible. To cartap hydrochloride, they showed from 10.5- to 33.3-fold resistant levels as high as the susceptible. Finally, based on $LC_{50}$ values to Bacillus thuringiensis by leaf disc technique, the resistant levels of the field populations were from 1.9 Lo 8.1 times as compared to the susceptible.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.196-203
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• 2004

In this study, a new gait phase detection system using both FSR(Force Sensing Resister) sensors and a gyrosensor was developed to detect various gait patterns. FSR sensors were put in self-designed shoe insoles and a gyrosensor was attached to the posterior aspect of a shoe. An algorithm was also developed to determine eight different gait transitions among four gait phases: heel-strike, foot-flat, heel-off and swing. The developed system was compared with the conventional gait phase detection system using only FSR sensors in various gait experiments such as level walking, fore-foot walking and stair walking. In fore-foot walking and stair walking, the developed system showed much better accuracy and reliability to detect gait phases. The developed gait phase detection system using both FSR sensors and a gyrosensor will be helpful not only to determine pathological gait phases but to apply prosthetics, orthotics and functional electrical stimulation to patients with gait disorders.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.41-46
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• 2009

We present experimental data on the time response behavior of industrial platinum resistance thermometers (IPRT) to help with the selection of proper sensors in industry and research laboratories. Time constants of IPRTs were measured using a method specified in ASTM standards. Two different sensors of different protecting sheath diameters were tested in air, water and silicon oil at temperatures from $0^{\circ}C$ to $200^{\circ}C$. The time constant was the smallest in water and the highest in air. As the test temperature increased, time constants tended to decrease at all heat conducting media. For different diameters of sheath of IPRT at the same temperature, it was found that the IPRT of larger diameter showed higher time constant in air, but the opposite dependence was observed in water and oil. From the measured results, it was suggested that the sensor diameter and heat conducting medium should be considered if one wants to select proper thermometer to measure the dynamic temperature change in industry and research area.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.831-838
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• 2014

Chip on glass (COG) bonding using anisotropic conductive film (ACF) is a key technology to assemble a driver IC onto a LCD glass panel. In this paper, an experimental investigation was conducted to investigate the correlation between contact resistance and characteristics of image taken by machine vision based inspection system. The results show that the contact resistance was strongly influenced by the contrast ratio of conductive particle rather than the number of conductive particles. Also, number of conductive particles whose contrast ratio is below 0.75 is crucial for determining the quality of the assembled samples. On the other hand, in the result of high temperature high humidity storage test, the contrast ratio of samples was increased. However, in the case of open-circuit samples after temperature humidity storage test, the number of conductive particles whose contrast ratio is above 0.75 was more than that of the closed-circuit samples.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.943-950
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• 2013

This paper describes the thermal contact resistance and its effect on the performance of thermal interface material. An ASTM D 5470 based apparatus is used to measure the thermal interface resistance. Bulk thermal conductivity of different interface material is measured and compared with manufacturers' data. Also, the effect of grease void in the contact surface is investigated using the same apparatus. The flat type thermal interface tester is proposed and compared with conventional one to consider the effect of lateral heat flow. The results show that bulk thermal conductivity alone is not the basis to select the interface material because high bulk thermal conductivity interface material can have high thermal contact resistance, and that the center voiding affects the thermal interface resistance seriously. On the aspect of heat flow direction, thermal impedance of the lateral heat flow shows higher than that of the longitudinal heat flow by sixteen percent.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.781-786
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• 2015

In this paper, we analyzed characteristic of window type current transformer and we performed the optimal design consider to the loss; in order to design the current transformer figured signal of overcurrent warning circuit. The core size of window type current transformer was determined by the secondary coil turns. We analyzed current waveform, which is appeared by the number of coil turns on the core, we made sure the relation of secondary coil turns and load resistance in order to improve the non-sinusoidal wave by the flux saturation of the current transformer core. Additionally, we did improvement of the accuracy and optimal design through the transformation of the inner diameter and the stack length when the outer diameter of core is sustaining.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.4
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• pp.85-96
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• 1988

The optimum cutting condition for rake angle in turning was investigated in (6-4) Brass and Al alloy. Results of experiments in (6-4) Brass and Al alloy are as follow. Specific cutting resistance becames higher as the depth of cutting, feed or cutting velocity decreases at same rake angle and resistance appear low value 20.deg., 25.deg.(6-4)brass, 0.deg. 20.deg.(Al alloy). The optimum cutting condition for(6-4) Brass is depth of cutting 0.5mm, rake angle 25.deg., cutting velocity 80m/min, feed 0.1mm/rev and for Al alloy is depth of cutting 0.1mm, rake angle 0.deg., cutting velocity 200m/min, feed 0.5mm/rev. The rake angle for good roughness is 20.deg. at (6-4) Brass, and that for Al alloy is 15.deg. The roughness is influenced by feed and it has the lowest value at 0.1mm/rev and the cutting condition is influenced by rake angle only.

• Membrane Journal
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• v.14 no.1
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• pp.66-74
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• 2004

Total resistance of membrane in a micro-filtration system using a metal membrane was mainly attributed to the permeate resistance of cake layer($R_c$), which was formed by deposited particles from the physico-chemical interactions of solids on membrane surface. Intermittent back ozonation was highly effective than the air backwashing for fouling reduction. As far the operational effect, under same ozone injection, the increase of gas flow-rate was more favorable than the increase of injection time far the recovery of permeation flux. As the filtration time was longer, the effect of flux recovery by intermittent back-ozonation decreased. Therefore, it is preferable to operate membrane cleaning before the foulant is consolidated on membrane surface.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.3
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• pp.54-59
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• 2008

A highly accurate wide swing BiCMOS cascode current mirror is proposed. It uses the base-current compensated BJT current mirror. It increases both output impedance and output voltage range by using the npn-NMOS cascode instead of the NMOS-NMOS cascode. The npn transistor copies the input current and the NMOS transistor increases the output impedance for the accurate current mirroring. The proposed current mirror achieves highly constant current for wide output voltage range. Simulation results were verified with measurements performed on a fabricated chip using a 5/16V 0.5um BCD process. It has only $-2.5%{\sim}1.0%$ current error for $0.3V{\sim}16V$ output voltage range.