• Journal of the Korean Magnetics Society
• /
• v.20 no.3
• /
• pp.94-99
• /
• 2010

Minor B-H loop measurement for a rectangular high tensile steel was obtained by using Labview. A ferrite cores of high permeance with primary and secondary windings on the steel plate were used to form a closed loop of magnetic flux. To compensate errors due to an extremely small gap between a pair of ferrite core, and between the ferrite core and the rectangular high tensile steel, quadratic function of least square method was used. Also a 3D FEM magnetic analysis tool was used to measure H and B of the steel. B-H loop of the high tensile steel plate can be measured up to 520 A/m of a magnetic field and 0.15 T of a magnetic flux density.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.2
• /
• pp.58.1-58.1
• /
• 2015

단주기 변광성들의 적외선 광도곡선이 가시광선 광도 곡선과 어떠한 차이가 있는지 알아보기 위해 주기가 하루 이내로 짧은 다양한 유형의 변광성을 대상으로 보현산 천문대의 1.8m 반사망원경과 적외선검출기(KASINICS)를 이용한 J($1.25{\mu}m$), H($1.64{\mu}m$), K($2.15{\mu}m$)필터 관측을 수행하였다. 관측 대상은 맥동변광성으로 분류되는 BO Lyn외 2개 대상, 격변변광성으로 분류되는 RX And외 3개 대상, 그리고 식변광성으로 분류되는 V1007 Cas외 1개 대상이다. IRAF를 이용한 전처리 및 구경 측광을 실시하여 각 필터별 적외선 광도곡선을 얻었다. 이를 통해 현재 각 분류 대상별 주기분석과 여러 해 동안 관측한 자료를 이용하여 각 대상들의 장주기에서의 변광 요인 유무도 확인하여 가시광선 광도곡선과의 비교 분석 연구를 수행하고 있다. 격변변광성의 경우 가시광 광도 곡선이 주로 강착원반의 더 뜨거운 내부고리와 대기에 의한 것인 반면 적외선 광도 곡선은 동반성과 차가운 강착원반에 의한 것이라 여겨지며, 맥동변광성과 식변광성의 경우도 가시광선과 적외선이 서로 다른 깊이를 보게 될 것이므로 파장대별 최대 밝기 위치와 광도 윤곽에서의 차이가 기대된다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.1039-1040
• /
• 2010

• Journal of the Korean Magnetics Society
• /
• v.24 no.3
• /
• pp.76-80
• /
• 2014

Toroidal cores made of metallic powder requires large magnetic field strength up to few decade kA/m to obtain major hysteresis loop. To overcome thermal heat generation problem from large exciting current during measurement, we have employed a real time hysteresis loop tracer which can digitize and calculate B-H signals in personal computer as real time. For example, when we magnetize specimen at 10 Hz frequency, we could display hysteresis loops 10 times per second. Using the real time hysteresis loop tracer, we could measure major hysteresis loop of toroidal shape metallic powder core at maximum flux density or maximum magnetic field strength to be measured within 5 second not to significant increasement of specimen temperature due to the heat dissipation from coil windings. For the constructed hysteresis loop tracer, we could measure hysteresis loop at magnetic field strength higher than 50 kA/m for the toroidal shape specimen.

• Journal of Biomedical Engineering Research
• /
• v.22 no.5
• /
• pp.403-412
• /
• 2001

The Present study analyzed the pressure-flow characteristics of a Korean shunt valve. Changes in the characteristic currie depending on the design parameters were also investigated. The Korean shunt valve used in the present study was constant pressure type and our analyses were validated through experiments. We applied fluid-structure interaction to solve the flow dynamic Problem because the small diaphragm in the valve was made from flexible silicone elastomers. Considering the material nonlinearity of the hyper-elastic material. the Mooney-Rivlin approximation was employed. The results of the numerical analyses were close to the experimental results The major Pressure drop was observed to happen in the small diaphragm. The slope of the pressure-flow characteristic curve was computed to be 0.37mm$H_2O$.hr/cc, which was similar to the average value of commercial shunt valves. 0.40mm$H_2O$.hr/cc. Therefore. our valves analyzed in the Present study showed a Proper Pressure control characteristics of the constant pressure type shunt valves. The opening pressure could be controlled by adjusting the amount of predeflection of the valve diaphragm. In order to obtain opening pressures of 25mm$H_2O$ and 80mm$H_2O$, respectively, and the required predeflection was found to be 10.2$\mu$m and 35.3$\mu$m. The flow orifice size was found to be within 10$\mu$m during valve operation Therefore, Precision design and manufacturing techniques are necessary for successful operations of the shunt valve. The study indicated the amount of predeflection as well as the magnitude of corner rounding of the diaphragm edge are important design parameters to influence the slope of the pressure-flow characteristic curve.

• Nuclear Engineering and Technology
• /
• v.5 no.1
• /
• pp.38-43
• /
• 1973

The spin-rotation constants of the proton and tile fluorine nucleus in C $H_4$, Si $H_4$, Ge $H_4$, C $F_4$, Si $F_4$ and Ge $F_4$ were determined experimentally by the molecular beam magnetic resonance method. From the Hamiltonian and the high field approximation, the quantized energy level is given by the following equation. W $m_{I}$ $m_{J}$=- $g_{I}$ $m_{I}$H- $g_{J}$ $m_{J}$H- $C_{av}$ $m_{I}$ $m_{J}$, where $c_{av}$ is one third of the trace of the C tensor. In the nuclear resonance experiment, the proton and the fluorine nuclear resonance curves consist of many unresolved lines given by v=- $g_{J}$H- $C_{av}$ $m_{I}$, and a Gaussian approximation is made to correlate $c_{av}$ to the experimentally obtained half-width of the resonance curve. In the rotational resonance experiment, the five resonance peaks as predicted by v=- $g_{I}$H- $c_{av}$ $m_{I}$, $m_{I}$=0, $\pm$1 and $\pm$2, were all observed. The magnitude of car was determined by measuring the frequency distance between two adjacent peaks. The sign of $c_{av}$ was determined by the side peak suppression technique. The technique is described, and the sign and magnitude of the spin-rotation constant cav are summarized as following: for C $H_4$ -10.3$\pm$0.4tHz(from the rotational resonance), for SiH +3.71$\pm$0.08kHz(from the nuclear resonance), for Ge $H_4$+3.79$\pm$0.13kHz(from the nuclear resonance), for C $F_4$, -6.81$\pm$0.08kHz(from the rotational resonance), for Si $F_4$, -2.46$\pm$0.06kHz(from the rotational resonance), and finally for Ge $F_4$-1.84$\pm$0.04kHz(from the rotational resonance).onal resonance).esonance).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.1075-1076
• /
• 2009

• Journal of the Korean Magnetics Society
• /
• v.14 no.6
• /
• pp.228-231
• /
• 2004

We have studied local magnetization reversal and magnetic properties induced by Laser annealing method in the strip-patterned Ta/NiFe/FeMn/Ta and Ta/NiFe/FeMn/NiFe/Ta multilayers fabricated by ion-beam deposition. The films were exposed to the emission of the DPSS (Diode Pumped Solid State, Nd:YAG) laser under 600 G. The laser beam intensity increased up to 440 mW. When the laser illuminated the patterned film with the power of above 200 m W, the intensity of MR peak located in +87 Oe shrunk. A new MR peak was generated at -63 Oe. When the laser power is 400 mW, the location of positive MR peak(H$\sub$ex/) was changed slightly from +87 Oe to +76 Oe, and the MR ratio was decreased from 0.9% to 0.1 %. On the other hand, the new (negative) MR peak shifted from -63 Oe to -80 Oe, with the MR ratio increased up to 0.3%. As the illuminated area expanded, the intensity of opposite MR peak increased and it of negative MR peak decreased. This proved that the local reversal of exchange biasing should be realized by laser annealing.

• 전자공학회논문지 IE
• /
• v.46 no.1
• /
• pp.31-36
• /
• 2009

This study was to simulate it that the sending receiving vehicles run on the general national roads with the one-way two-lanes at 80[km/h] speed. This study was to select 280[m] radius of curvature based on the statistical data with high rate of traffic accidents, 140[m] length of direct roads considering the stopping stadia, 90[m] length of curve, and 8 points of curved roads at 11.25[m] intervals. As a result above, when the distance between the sending and receiving vehicles became more than 111[m], the propagation path of reflected wave by the adjacent vehicles became longer than the propagation path of reflected wave by the left/right reflectors because the number of repeated reflection increased. In this study, the repeated reflection for the propagation's reach to the receiving vehicles was about $1{\sim}2$[times] as it supposed it less than 111[m]. Accordingly, it found out that the propagation path of reflected wave received through the left/right reflectors was about $1{\sim}1.5[m]$ larger than the reflected wave produced by the adjacent vehicles regardless of lanes on which the sending and receiving vehicles were located.

• Applied Chemistry for Engineering
• /
• v.10 no.7
• /
• pp.969-973
• /
• 1999

In this work, we studied the degree of hydrolysis of ion exchanger in $NH_4OH$ solution and sorption characteristics of $NH_3$ by potentiometric titration curves with using carboxylic acid ion exchanger Fiban K-4. We knew that the theoretical pH values agreed with the experimental pH values on the $NH_4OH$ concentrations in various concentrations of supporting electrolyte $(NH_4)_2SO_4$. The sorption values of $NH_3$ using the ion exchanger can be calculated from equivalent sorption curves for various pH. Also, the degree of hydrolysis increased with decreasing concentration of supporting electrolyte and pH. In order to obtain the mono ion form below 0.01 M as the decreasing concentration of supporting electrolyte, the pH values should be increased. From these results, therefore, the concentrations of supporting electrolyte and pH values were determined.