• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.165-168
• /
• 2004

Due to the demolition of old structures, primarily buildings, an amount of discharged construction wastes are increased. From the construction wastes, recycled aggregate can be used as a useful resource for concrete. However, its application to structural member is very limited. In this experimental study, the compressive strength of spun-concrete using recycled aggregate was investigated. Coarse aggregate was replaced with $100\%$ of the recycled coarse aggregate, and recycled fine aggregate was replaced with various amount. According to the test results, the specimen of spun-concrete showed uniform compressive strength regardless the amount of replaced recycled fine aggregate.

• Bulletin of the Korean Space Science Society
• /
• 2009.04a
• /
• pp.64.2-64.2
• /
• 2009

• Proceedings of the KIPE Conference
• /
• 2008.10a
• /
• pp.121-123
• /
• 2008

A high efficiency soft switching boost converter is proposed in this paper. The conventional boost converter generates switching losses at turn on and off. Because of those, the whole system efficiency is reduced. The proposed converter utilizes soft switching method using resonant circuit with an auxiliary switch. Therefore, the proposed converter reduces switching losses lower than the hard switching. The proposed soft switching boost converter can be applied to photovoltaic system, power factor correction circuit and etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.476-477
• /
• 2007

This paper described the partial discharge (PD) measurement techniques for diagnosing gas-insulated switches in overhead power distribution system. A capacitive voltage probe to detect PD pulse was designed and fixed on the surface of a bushing. We also designed a coupling network to attenuate AC voltage by 270 dB, and a low-noise amplifier having the gain of 40 dB and 500 kHz~20 MHz 3 dB. From the calibration, it was calculated that the sensitivity of the measurement system was 0.94mV/pC. In the application experiment, we could measure a PD pulse of 45 pC.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.219-224
• /
• 2008

The purpose of this paper is to acquire the data related to insulation evaluation of hybrid vehicle traction motors. We carried out a comparative analysis on Insulation Resistance (IR) and Polarization Index (PI) of motor stators according to IEEE Std. 43 and IEC 60085-1 for insulation resistance test standard of rotating machinery. Maximum test voltage which is applied to between a phase and enclosure was set at 500 V. The IRs of the used motors were lower than those of the new ones. The PIs of the used motor were ranges from 0.74 to 1.1 and did not meet the recommendation basis 2 for insulation level H. From the experimental results, we could prepare parameters and basis for insulation evaluation of motor stators by comparative analysis of the IR and the PI.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.27-32
• /
• 1999

We developed a 40-channel superconducting quantum interference device (SQUID) system for neuromagnetic measurements. The main features of the system are use of double relaxation oscillation SQUID (DROS), and planar gradiometer for measuring tangential field components. The DROSS with high flux-to-voltage transfers enabled direct readout of the SQUID output by room-temperature electronics and simple flux-locked loop circuits could be used for SQUID operation. The pickup coil is an integrated first-order planar gradiometer with a baseline of 40 mm. The average noise of the 40 channels is around 1.2 fT/cm/${\sqrt{Hz}}$ at 100 Hz, corresponding to the field noise of 5 fT/${\sqrt{Hz}}$ at 100 Hz, operated inside a magnetically shielded room. The 40-Channel system was applied to measure auditory-evoked neuromagnetic fields.

• Horticultural Science & Technology
• /
• v.35 no.1
• /
• pp.11-20
• /
• 2017

The objective of this study was to determine whether inoculation with Bacillus licheniformis MH48 as a plant growth-promoting rhizobacterium (PGPR) could promote nutrient uptake of seedlings of the ornamental plant Camellia japonica in the Saemangeum reclaimed coastal land in Korea. B. licheniformis MH48 inoculation increased total nitrogen and phosphorus content in soils by 2.2 and 20.0 fold, respectively, compared to those without bacterial inoculation. In addition, B. licheniformis MH48 produced auxin, which promoted the formation of lateral roots and root hairs, decreased production of growth-inhibiting ethylene, and alleviated salt stress. Total nitrogen and phosphorus uptake of seedlings subjected to bacterial inoculation was 2.3 and 3.6 fold higher, respectively, than the control. However, B. licheniformis MH48 inoculation had no significant effect on the growth of seedlings. Our results suggest that inoculation with B. licheniformis MH48 can be used as a PGPR bio - enhancer to stimulate fine root development, promote nutrient uptake and alleviate salt stress in ornamental plant seedlings grown in the high-salinity conditions of reclaimed coastal land.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.201-204
• /
• 2001

본 논문에서는 전력케이블, 전력용 변압기 및 가스 절연차단기와 같은 전력설비의 열화로 인한 방전현상 검출을 위해서 간섭계형 광섬유 센서를 제작하고, 방전 현상을 측정하였다. 광섬유 센서는 아크릴과 알류미늄 광섬유를 수회 감은 맨드릴형으로 선택하였으며, 간섭계는 Sagnac 간섭계를 선택하여 실험하였다. 방전현상은 절연유내에 방전모의셀을 설치하여 방전현상을 일으켰고, 광섬유 센서로 방전신호를 검출하였다.

• Proceedings of the KSCN Conference
• /
• 2005.04a
• /
• pp.185-185
• /
• 2005

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.6
• /
• pp.1169-1175
• /
• 2009

In this paper, the inferences of data obtained from periodic inspection and type I censoring for the step-stress accelerated life test are studied. The exponential distribution with a failure rate function that a log-linear function of stress and the tampered failure rate model are considered. The maximum likelihood estimators of the model parameters are estimated and also the optimal stress change time which minimize the asymptotic variance of maximum likelihood estimators of parameters is determined. A numerical example will be given to illustrate the proposed inferential procedures and the sensitivity of the asymptotic variance of the estimated mean by the guessed parameters is investigated.