• Journal of Sensor Science and Technology
• /
• v.4 no.1
• /
• pp.15-20
• /
• 1995

This paper deals with the planar-type sensor which can measure the time-varying electric fields. To make an electric field measurement system having a wide bandwidth, a planar-type sensor is proposed. The theoretical principle and design rule of the measuring device are introduced, and also the calibration and application investigations are carried out. From the calibration experiments, the frequency bandwidth of the electric field measurement device ranges from 160 [Hz] to 25 [MHz] and the sensitivity of the sensor is 1.2 [mV/V/m]. As the application experiments, the electric fields caused by the impulse and oscillating transient voltage in high voltage laboratory are measured by the proposed device, and the results are excellent.

• Journal of the Korean Ceramic Society
• /
• v.26 no.2
• /
• pp.210-220
• /
• 1989

The properties of the powder of Al2O3-15v/o ZrO2(＋3m/o Y2O3) system prepared by co-precipitation method at the pH values of 7, 9, 10 and 11 were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Zirconium hydroxide decreased the specific surface area of aluminum hydroxide of AlOOH type, while increased the specific surface area of aluminum hydroxide of Al(OH)3 type, and formed co-network structure of Al-O-Zr type with the aluminum hydroxides. The rate of transition to $\alpha$-Al2O3 from co-precipitated materials occurred in the order of 7≒10, 9 and 11 of pH values. Al2O3 and ZrO2 interacted to bring about coupled grain growth, and the growth of ZrO2 crystallite size rapidly occurred within $\theta$-Al2O3 matrix. Segregation did not occur in the system Al2O3-15v/o ZrO2(＋3m/o Y2O3) and Y2O3 acted as a stabilizer to ZrO2. The lattice strain of tetragonal ZrO2 was increased by the constraint effect of Al2O3 matrix.

• Journal of the military operations research society of Korea
• /
• v.8 no.1
• /
• pp.77-98
• /
• 1982

Experiments have been performed for estimating the individual muscle capabilities of the biceps brachii and the quadriceps femoris muscle. The surface EMG has been recorded on the bellies of the biceps brachii and the quadriceps femoris muscle during isometric contractions at $50\%,\;75\%,\;and\;100\%$ MVC. The rectified EMG amplitudes of the maximum voluntary contraction (MVC) were in the range of $2.8\~3.0\;mV\;and\;6.9\~7.2\;mV$ the biceps brachii and the quadriceps femoris, respectively. In the biceps brachii, Type S motor units were recruited in the range of $41\~49\%$ MVC; and Type F motor units were recruited in the range of $51\~59\%$ MVC, In the quadriceps femoris, Type S, Type SF, and Type F motor units were recruited in the ranges of $31\~38\%,\;33\~48\%$, and $21\~29\%$ MVC respectively.

• Journal of Sensor Science and Technology
• /
• v.23 no.6
• /
• pp.392-396
• /
• 2014

The 2-dimensional silicon vertical Hall devices, which are sensitive to X,Y components of the magnetic field parallel to the surface of the chip, are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-$SiO_2$ interface and n-epi layer to improve the sensitivity and influence of interface effect. Experimental samples are a sensor type K with and type J without $p^+$ isolation dam adjacent to the center current electrode. The results for both type show a more high sensitivity than the former's 2-dimensional vertical Hall devices and a good linearity. The measured non-linearity is about 0.8%. The sensitivity of type J and type K are about 66 V/AT and 200 V/AT, respectively. This sensor's behavior can be explained by the similar J-FET model.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.7
• /
• pp.1224-1230
• /
• 2007

In this paper, we study the classification of defects at steam generator tube in nuclear power plant using eddy current testing (ECT). We consider 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. In order to improve the classification performance, we propose new feature extraction technique. After extracting new features from the generated ECT signals, multi-layer perceptron is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves 100% classification success rate while the previous method yields 91% success rate.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.484-486
• /
• 2002

In this paper, installation type is analyzed into a single and mixed burying type on burying situation of domestic underground transmission cables, and problem of underground cable is discussed with investigating the relation between burying type and sheath circulation current. Investigated cable systems are 520 T/L which have 512T/L for 154kV and 8T/L for 345kV. The authors consider that the analysis of sheath circulating current with burying type will contribute for setting reduction methods of sheath circulation current.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.293-298
• /
• 1997

Corrosion of steel reinforcing in concrete deteriorated by freezing/thawing and carbonation was characterized. Concrete specimens were prepared using various kinds of cements such as ordinary portland cement (type I), low heat portland cement (type IV, belite rich cement), sulphate resistance portland cement (type V), blast furnace slag portland cement and ternary blended cement. Of various cements, type V and type IV with lower $C_3A$ content revealed better steel corrosion resistance after freezing/thawing and carbonation. $C_3A$ content in cement might affect freezing/thawing resistance in sea water.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.10a
• /
• pp.32-35
• /
• 2004

The development of automotive rear chassis part using tube forming process has advantage of increase in part durability and decrease in its weight. We developed tubular type rear CTBA(Coupled Torsion Beam Axle) part with 60K high strength steel developed by POSCO in this project. The result was demonstrated that tubular type CTBA shows excellent durability performance and $10\%$ weight reduction compared with V-beam type CTBA in our work. Furthermore, we will adapt this technology to mass production and apply to the other chassis parts.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.12
• /
• pp.614-621
• /
• 2001

In this Paper, the ozonizer is fabricated by piling plate-type electrodes up to minimize and reduce install space. Hereby ozone generation characteristics of piled plate-type ozonizer were investigated. Inverse-polarity voltage was generated by H.V neon transformer. And 2 H.V neon transformers were used to supply high voltage each 9 electrodes of plate-type ozonizer. According to the experiments, ozone concentration, generation and yield were proportionally increased tilth increasing the number of electrode. And the maximum increase effects of 246%, 245%, and 33% were obtained when the number of electrode were increased from 3 up to 9.

• Journal of Sensor Science and Technology
• /
• v.20 no.4
• /
• pp.260-265
• /
• 2011

The silicon vertical hall devices are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-$SiO_2$, interface and n-epi layer without $n^+$buried layer to improve the sensitivity and influence of interface effects. Experimental samples are a sensor type I with and type H without p+isolation dam adjacent to the center current electrode. The experimental results for both type show a more high current-related sensitivity than the former's vertical hall devices. The sensitivity of type H and type I are about 150 V/AT and 340 V/AT, respectively. This sensor's behavior can be explained by the similar J-FET model.