• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.2C
• /
• pp.99-108
• /
• 2006

In this study a series of bench scale test are conducted to increase the undrained shear strength of clayey soils using by Electro-kinetic injection stabilization method. The sodium silicate was injected in anode reservoir and its concentration was changed with 500, 1000, 1500, 2000, 2500mM for configuration of applicability of Electro-kinetic injection stabilization method. Also, the treatment time and electric gradient was changed to acquire the optical influence factors. For increasing the shear strength to maximum values, the calcium chloride and aluminium hydroxide, which concentration was changed with 50, 250, 500, 750, 1000mM, were added at anode reservoir for 5 days after the treatment of sodium silicate in 5 days as the 2nd additives. The test of results in determination of sodium silicate concentration show that the undrained shear strength at each point had a tendency to converge into a constant value when the concentration of sodium silicate came to 1000mM and above. The maximum shear strength increasement was 800% compared with initial value. After a series of test, the electric gradient and treatment time for application of electric fielld were 1V/cm and 6 days. In case of 2nd additives test, the concentration for maximum shear strength is 250mM in all additives and the effects of shear strength improvement was developed approximately 20~30% in comparison to addition of single injection material.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.4
• /
• pp.292-301
• /
• 2001

IDDQ Testing is a very effective testing method to detect many kinds of physical defects occurred in CMOS VLSI circuits. In this paper, we consider the most commonly occurring bridging faults in current CMOS technologies and develop pattern generator for IDDQ testing using efficient IDDQ test algorithms. The complete set of bridging faults between every pair of all nodes(internal and external nodes) within circuit under test is assumed as target fault model. The merit of considering the complete bridging fault set is that layout information is not necessary. Implemented test pattern generator uses a new neighbor searching algorithm and fault collapsing schemes to achieve fast run time, high fault coverage, and compact test sets. Experimental results for ISCAS benchmark circuits demonstrate higher efficiency than those of previous methods.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.3
• /
• pp.486-495
• /
• 2006

In this paper, a low-power 1Kb synchronous EEPROM is designed with flash cells for passive UHF RFID tag chips. To make a low-power EEPROM, four techniques are newly proposed. Firstly, dual power supply voltages VDD(1.5V) and VDDP(2.5V), are used. Secondly, CKE signal is used to remove switching current due to clocking of synchronous circuits. Thirdly, a low-speed but low-power sensing scheme using clocked inverters is used instead of the conventional current sensing method. Lastly, the low-voltage, VDD for the reference voltage generator is supplied by using the Voltage-up converter in write cycle. An EEPROM is fabricated with the $0.25{\mu}m$ EEPROM process. Simulation results show that power dissipations are $4.25{\mu}W$ in the read cycle and $25{\mu}W$ in the write cycle, respectively. The layout area is $646.3\times657.68{\mu}m^2$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.650-658
• /
• 2017

A grounding system in a large-scale apartment complex consists of a TT grounding system when viewed in each building unit, but the characteristics of TN grounding system appears when viewed in the total ground system function. Therefore, this study examined the characteristics of a grounding system in a large-scale apartment complex using design draft, field measurements and PSCAD/EMTDC modeling. This paper proposes an algorithm for fault analysis depending on the grounding system structure in large-scale apartment complexes considering the connection of the underground culvert as well as a design algorithm for each grounding system considering the contact voltage and step voltage. The simulation results based on the proposed modeling and algorithm confirmed that it is useful for analyzing the characteristics of a grounding system in a large-scale apartment complex.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.14 no.6
• /
• pp.18-25
• /
• 2000

This paper describes the design and fabrication of a home-panel board for electromagnetic compatibility which can protect home-electric appliances from transient voltages and power line noise. The proposed panel board include a transient voltage blocking device and a EMI filter which consisted of varistors, capacitors, and bus line inductance.A performance test of the prototype panel board, blocking characteristics to transient voltages and reduction characteristics to power line noise, are carried out by using a combination surge generator standardized in IEC and a network analyzer.The results showed that the proposed panel board is satisfied with the surge immunity level of IEC 61000-4-5, and has an over 20[dB] noise reduction performance in ranges from 150[kHz]∼30[MHz].

• Journal of Sensor Science and Technology
• /
• v.3 no.1
• /
• pp.12-18
• /
• 1994

In this study, we fabricated and characterized a calorimetric-type flow sensing element using a micromachined silicon substrate. The cooling and heating effects resulted from the gas flow were measured by two temperature sensors located at both sides of the heating resistor, and the insulator diaphragm was employed as a substrate in order to improve thermal isolation. The sensor generated $0{\sim}378.4mV$ output signal under 10V bridge-applied voltage when the nitrogen gas was passed on the sensor surface having a mass flow rate of $0{\sim}0.25grs/min$, and reached to the stable operating condition within 10 seconds.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1153-1154
• /
• 2011

본 논문은 3상 30kW 및 50kW 계통연계형 태양광 인버터의 개발에 관한 것으로, 그에 대한 제어기 및 성능에 대해 소개한다. 본 논문에 소개되는 3상 30/50kW LSPV 태양광 인버터는 태양전지에서 발생하는 가변성 직류에너지를 한전계통에 최적으로 주입시키는 계통연계형 전력변환장치이며 국내의 발전사업자용으로 개발되었다. 3상 380V의 한전계통에 절연형으로 연계되며 낮은 THD 와 높은 역률로 고효율을 달성하였다. DC입력측의 개방전압은 900V로 태양전지모듈 조합의 편의성 및 DC과전압등에 대한 안전성을 향상하였고, EMI 전도노이즈에 대한 Filter를 장착하여 노이즈성분을 크게 개선하였다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.3
• /
• pp.297-302
• /
• 2002

The direct torque control(DTC) of induction machines has the advantages of a simple control scheme and a very quick and robust torque response and its application is extended in the traction field. However, some drawbacks of the conventional DTC strategy using a hysteresis controller are the relatively large torque ripple in the steady state and the variation of switching frequency according to the amplitude of hysteresis bands and the motor operating conditions. In this paper, a navel direct t()roue control scheme of induction machines based on stator flux control and Space Vector Modulation Is proposed to acquire the advantage of a fixed switching period and the minimization of the torque and stator current ripple in a wide speed range. The effect of proposed method has been proven by simulations and experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.437-442
• /
• 2001

Recently, transformerless inverters have been studied to reduce sizes and costs of utility-connected PV systems. This paper presents a transformerless PV inverter using a two-phase boost converter of reduced ripples in input current and output voltage, low voltage stress of semiconductor device and reduced size of input reactor. And new PWM method is introduced, whose on-off time is calculated from simultaneous equation induced by fourier series. To verify a validity of the proposed transformerless inverter, computer simulation has been carried out.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.6
• /
• pp.1057-1064
• /
• 2017

High sensitivity magnetic sensor having foreign metal detection capability is proposed utilizing giant magneto-impedance effect. Strip sensor showed the increasing output voltage when the external magnetic field was applied along with strip from strip grounding point, although the initial DC voltage varied depending on the pointing direction of strip sensor. Proposed sensor was able to eliminate more than half of background noise using active noise filter to achive high sensitivity, and it showed the capability to detect magnetized foreign metal object independent of ambient electro-magnetic noise and earth magnet. In case of ferrous sphere, the metal detection up to 0.8mm diameter was experimentally demonstrated at 5mm distance from strip sensor.