• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.2
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• pp.24-33
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• 1971

A noble method of delta modulation by means of pair transistor circuit having negative resistance charcteristic is presented. An RC parallel circuit is inserted between two eiuitter tarminals of the pair transistor circuit, and their emitters are driven by a square pulsed current source. Basically this is a relaxation oscillator circuit. But when the value of capacitors and resistanc R, and the pulse height of driving source are properly chosen, the RC parallel circuit apparently functions as integrating circuit of driviving pulses. Compared with the integrated voltage of capacitor C, a signal input voltatage supplied in series with RC parallel circuit between two emitters makes on or off either of the pair transistors. as the result, one bit pulse is sent out from the coupling resistance terminal of conducted transistor. The circuit diagram used for this experiment is presented, it i% composed with simple mod ulster circuit, differential amplifier and pulse shaping amplifier, The characteristics of the components of this ciruit are discussed, and especially quantumized noise in this delta modulation system is discussed in order to improve the signal to noise ratio which has a close relation with circut constants, quantumized voltage, pulse height and width of driving current source.

• Fire Science and Engineering
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• v.31 no.3
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• pp.63-72
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• 2017

This study fabricated a low-voltage 10 circuit distribution board based on the KEMC (Korea Electrical Manufacturers Cooperative) 2102-610 standard and performed a characteristics assessment of the developed 10 circuit distribution board to secure product stability. The developed 10 circuit distribution board is designed to have the characteristics of insulation materials, as well as resistance to corrosion ultraviolet radiation and mechanical impact. The developed distribution board is fabricated to have an appropriate protection class of enclosure, electric shock prevention and protection circuits, switchgear and its components, internal electrical circuits and connectors, external conduct terminal, insulation characteristics, temperature rise test, heat resistance, etc. The developed 10 circuit distribution board consists of a single phase circuit and 3-phase circuits. It is possible to measure in real time the leakage current generated from the load distribution line by installing a sensor module at the load side of each of the branched switchgears. In addition, it is possible to increase a circuit according to the use and purpose of the load and to also manage and check the load in real time. Temperature rise tests were performed on the developed 10 circuit distribution board at 18 places including the inlet connection, main circuit and distribution circuit bus bars and bus bar supports, etc. The highest temperature of $65.3^{\circ}C$ was measured at the R-Phase of the connection of the MCCB power supply for the branch circuit bus bar and a temperature rise of $61.6^{\circ}C$ was measured at the T-Phase of the load side. When applying thermal stress to an MCCB for 6 hours at $180^{\circ}C$ using a heat resistant experimental device, it was found that the actuator lever was transformed and moved in the tripped state.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.536-544
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• 1997

This study presents test results of a residential window system air-conditioner using R22 and two potential alternative refrigerants, R407C and R410B. A series of performance tests was performed for the basic and liquid-suction heat exchange cycle in a psychrometric calorimeter test facility. For R407C, the same rotary compressor was used as in the R22 system. However, compressor for the R410B system was modified to provide the similar cooling capacity. The evaporator circuit was changed to get a counter-cross flow heat exchanger to take advantage of zeotropic mixture's temperature glide, and liquid-line suction-line heat exchange cycle was also considered to improve the performance of the system. Test results were compared to those for the basic R22 system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.4
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• pp.156-160
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• 1982

A Comb Filter(C.F.) is constucted with a N-stages one-dimensional B.B.D.(Bucket-Brigade Device) delay line. One channel of the B.P.F. (Band Pass Filter) Bank is experimented, which includes a R.F.(Recursie Filter) using S/H circuits cascaded to the C.F. This algorithm of the C.F.B.(Comb Filter Bank) becomes the parallel spectrum analyzer circuit. The algorithm has less number of multiplication than that of FFT and improves the SNR.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.158-163
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• 2010

In this paper, we implemened the simplified Chua's circuit which is replace L to C by real hardware implementation. Because L element has a difficult problem to make a real hardware, L has a saturation characteristic and we also compare with previous Chua's circuit as the result of chaostic attractors creation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2416-2419
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• 2009

We performed frequency response measurements of four tuning fork crystal oscillators with different sizes and analyzed their measured electrical equivalent circuit parameters of R, L, $C_S$, and $C_P$ as functions of the linear dimensions, length, width, and thickness. We observed that R and L showed an decreasing behavior with increasing length while $C_S$, and $C_P$ showed an increasing behavior. Similar dependences of the electrical parameters on thickness were also observed. On the contrary, any noticeable dependence of these parameters on width has not been found.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.847-848
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• 2006

R-type thermocouple(TC) interface circuits with cold-junction compensator(CJC) and its broken wires detection was developed. The circuit consists of a CJC device, a instrumentation amplifier(IA), and two resistor and a diode for broken wire detection. The experiment results show that the interface circuit has a good CJC function on the temperature range for $20^{\circ}C$ to $1400^{\circ}C$. At the range the output voltage of the IA was -14V when the TC was broken. At normal operation condition the output voltage of IA was 0V to 10V for the temperature range.

• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.131-134
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• 2007

An $ITO/Alq_3/Al$ structure was used to study complex impedance of $Alq_3$ based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of $ITO/Alq_3/Al$ with a thickness layer of $Alq_3$ of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance of $R_s$.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.30-32
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• 2001

There are many difficult problems in analyzing the flow characteristics in a high voltage circuit breaker such as shock wave and complex geometries, which may be either static or in relative motion. Although a variety of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a gas circuit breaker is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program for analyzing the compressible flow fields in a high voltage gas circuit breaker using the Cartesian cut-cell method based on the CFD-CAD integration, which can achieve the accurate representation of the geometry designed by a CAD tools. This technique is frequently satisfied, and it will be almost universally so in the future, as the CFD-CAD traffic increase.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.224-230
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• 2016

In this study, a single-power-conversion series-resonant ac-dc converter with high efficiency and high power factor is proposed. The proposed ac-dc converter consists of single-ended primary-inductor converter with an active-clamp circuit and a voltage doubler with series-resonant circuit. The active-clamp circuit clamps the surge voltage and provides zero-voltage switching of the main switch. The series-resonant circuit consists of leakage inductance $L_{lk}$ of the transformer and resonant capacitors $ C_{r1}$ and $ C_{r2}$. This circuit also provides zero-current switching of output diodes $D_1$ and $D_2$. Thus, the switching loss of switches and reverse-recovery loss of output diodes are considerably reduced. The proposed ac-dc converter also achieves high power factor using the proposed control algorithm without the addition of a power factor correction circuit and a dc-link electrolytic capacitor. A detailed theoretical analysis and the experimental results for a 1kW prototype are discussed.