• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.83-93
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• 2007

This paper represents the development of 3-axises loadcell for measuring the side-force of suspension module of MPV(Multi Purposed Vehicle). The side force causes the failure of damper, such as leakage. The loadcell was developed using strain gauges, and the Wheastone bridge circuit to compensate for the cross-talk between the each axises and the measurement error by temperature. Structure analysis of loadcell was accomplished with FEM(Finite Element Method) to optimize the location of strain gages. The design optimization for important factors that have an effect on performance of loadcell was accomplished by using DOE(Design of Experiment). Loadcell was produced and successfully tested, showing good sensitivity and low cross-talk. The cross-talk of the developed loadcell is bellow 5%. The load history was measured at proving ground. The maximum side-force, the longitudinal force, and vertical force of MPV are 4.2 kN, 8.0 kN, and 17.0 kN, respectively, at Belgian road.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.207-213
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• 1996

A ternary compound semiconductor $Al_{x}$-Ga/1-x/Sb crystals which have energy gap from 0.7eV to 1.6ev at room temperature with the composition ratio were grown by using the vertical Bridgman method. The characteristics of $Al_{x}$-Ga/1-x/Sb were investigated in this study. The lattice constants of $Al_{x}$-Ga/1-x/Sb crystals with the composition ratio were appeared from 6.096$\AA$ to 6.135$\AA$ with the composition ratio. The electrical properties of the $Al_{x}$-Ga/1-x/Sb crystals measured the Hall effect by van der Pauw method at the magnetic field of 3 kilogauss and at room temperature. The resistivity of Te-doped $Al_{x}$-Ga/1-x/Sb crystals increased from 0.771 $\Omega$-cm to 5 $\Omega$-cm at room temperature with increasing the composition ratio. The mobility of Te-doped $Al_{x}$-Ga/1-x/Sb crystals varied with the composition ratio x, within the following three different regions, such as GaSb-like (0$\leq$x$\leq$0.3), intermediate (0.3$\leq$x$\leq$0.4) and AlSb-like (0.4$\leq$x$\leq$1).eq$1).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.1-9
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• 2003

In this paper, prototype of high-power-factor single-stage electronic ballast for fluorescent lamp is designed and implemented. A new low cost single stage high power factor electronic ballast for fluorescent lamps is based on integration of two-boost converter and LC type high frequency resonant inverter. The proposed ballast is combined by simple construction, because full bridge rectifier diode is eliminated and simple control circuit is applied. Boost converter operate in the voltage of positive and negative half cycle respectively at line frequency (60㎐), operation in discontinuous conduction mode performs high power factor. The experimental results show the good performance as PF 0.99, THD 15.4%, and CF 1.65 at output 63.5〔W〕.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.616-621
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• 2005

We considered of the buck and half bridge series DC-DC converter. It has good applications in areas with low voltage/high current, wide input voltage. The buck converter ratings and the half bridge converter ratings are $36\~72V$ input and 22V/5A output, $19\~24V$ input and 3.3V/30A output, respectively. Developed the buck and half Bridge series DC-DC converter ratings are of $36\~72V$ input and 3.3V/30A output. The buck converter is operated with zero voltage switching process to reduce the switching losses. The $80.1\%\~97.6\%$ of the efficiency is measured at $18.4{\mu}H$ output filter inductance of buck converter. In the half bridge converter, the $86\%\~96.4\%$ efficiency is measured at 150kHz switching frequency with PQI core. In the case of synchronized the buck and half bridge DC-DC converter, the measured efficiency is higher than that of the unsynchronized converter. In the synchronized converter, the maximum efficiency is measured up to $92.3\%$ with PQI core at 150kHz. 7A output.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.2
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• pp.269-276
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• 2023

In this research works, we propose a hybrid power generation system for drone capable of staying in the air for more than 1 hour. This power system converts the alternating current generated by the generator into direct current through a diode bridge circuit to charge the battery and uses a battery system having separated cells to obtain high controllability of the power system. The fuel efficiency and the power output for individual load were analyzed, and also the performance of a selected generator was studied in this paper. The drone which is equipped with the proposed hybrid power generation system calculated 0.82 ratio for weight vs power output, and flight time of drone showed 4,179 seconds.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.37-42
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• 2008

Purpose: The objective of the study: At present, the spectacles, with its use as a medical aids or a fashion trimming, are recognized as one of the living necessities which can't be separated from human body. One of the features of spectacles is that it must be worn on any part of human body. Such a feature has to be satisfied under the condition an user keeps feeling comfortable with the rim of spectacles worn. In order to ensure meeting this condition, a criterion has to be arranged for the design of the rim of spectacles. In order to manufacture a rim of spectacles which allows an user to secure a comfortable range of vision as well as enhancing the feeling when to be worn, a manufacturing standard has to be established based on optical science. No precise rim of spectacles could be made from the manufacturing method depending on the manufacturer's sensibility. When the rim of spectacles was manufactured according to the incorrect standards, it may cause an user such a fatal result as myopia, hyperopia or astigmatism. Methods: This study focuses on providing a detailed explanation about the design of rim, which is the most important element during designing a rim of spectacles, making use of the optical elements of spectacles, and helping the manufacturers and the people who work in the spectacles-related business understand and recognize what is correct and exact and then leading them to establish a standard in respect to the manufacture and selection of spectacles. Results, Conclusions: Considering the fact there happen many errors in relation with the names of rim stipulated in the provisions of International Standards Organization (ISO), due to wrong interpretation by some of the rim manufacturers, the right interpretation should be given about the bridge which is directly connected to rim, so that the rims of spectacles manufactured in Korea could keep a favorable position in competing with the foreign products of same kinds.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.405-412
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• 1999

Meta! Halide Discharge(]\1HD) Iamps have good color rendition, long life and good focusing capability but h have flickers bv acoustic resonances. We have designed the electronic ballast for reducing acoustic resonances in high pressure discharge tube. The ballast consists of main two parts, the first part is a half-bridge inverter to make a square wave form a and the st'Cond part is a flyback converter to combine the low frequency and high frequency component. As a r result of this study, we conclude that MHD lamps of 70 watt 따c very well light(D without acoustic resonance p phenomena by the elestronic ballast.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.88-93
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• 1999

In this paper, a new Mac-wave detection system by strain gage is constructed for study on a Mac-wave which is major factor of diagnosis in oriental medicine. Inherent resistance of a strain gage is linearly changed with strain of the sensor, thus the Mac-wave of wrist can be detected by using of the strain gage. A precision bridge circuit and high sensitive amplifier is designed for detecting the change of resistance of the strain gage in this experiments. A very small change of Mac-wave is acquired in the circuit. And the digital signal of the detected Mac-wave are acquired on a PC by multichannel A/D converter and displayed graphically by programming. The characteristics of the Mac-wave of sampled 6 persons in the time and the frequency domain are analysed, therefore the usefulness of the system constructed in this experiments are proved.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.4
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• pp.102-112
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• 1992

The three-phase full(6-pulse) bridge controlled rectifier is one of the most widely used types of solid-state converters in DC drive applications for higher performance. In most of the previous designs, the gate control circuits of the converter have been designed with analog method which can be easily affected by noise. Nowdays with advances of microelectronics and power electronics, microprocessor and pheripal LSIs are increasingly used for eliminating this problems. In this paper, a novel general-purpose microprocessor -based firing system and control scheme for a three-phase controlled rectifier bridge has been developed and tested. Using the phase relations between ${\Delta}$-Y transformer in power operation part, gate pulse of the converter is generated with real time process so that microprocessor may share its time to control algorithms efficiently. The firing angle of the converter is smoothly controlled in the range of 0 $^{\dirc}$ to 180$^{\dirc}$ with a fast respone and a constant open loop gain, even for the case where the converter is fed by a weak AC system of unregulated frequency. The hardware and software control circuit implementation built around a 80286 microprocessor is discussed, and the experimental results are given. This scheme uses less hardware components and has higher dynamic performance in variable speed DC drive applications.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.771-783
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• 1995

A simplified model for the so-called ACRT(accelerated crucible rotation technique) Bridgman crystal growth was considered in order to investigate the principal effects of the periodic variation of angular velocity. Numerical solutions were obtained for Ro=0.5, Ra=4.236*10$_{6}$ and E=2.176*10$^{-3}$ . The effects of spin-up process combined with natural convection was investigated as a preliminary study. The spin-up time scale for the present problem was a little larger than that observed for homogeneous spin-up problems. Numerical results reveal that over a time scale of (H$^{2}$/.nu..omega.$_{f}$)$^{1}$2/ the forced convection due to the formation of Ekman layer predominates. When the state of rigid body rotation is attained, natural convection due to buoyancy emerges as the main driving force and them the steady-state is approached asymptotically. Based on our preliminary results with simple spin-up, several fundamental features associated with variation of rotation speed are successfully identified. When a periodic variation of angular velocity was imposed, the system response was also periodic. Due to effect of mixing, the heat transfer was enlarged. From the analysis of time-averaged Nusselt number along the bottom surface the effect of a periodic variation of angular velocity on the interface location could be indirectly identified.d.