• Journal of KSNVE
• /
• v.3 no.4
• /
• pp.373-382
• /
• 1993

Active micro-vibration control of a structure, which simulates a stepper device, is performed using a pair of piezolectric actuators. The control aims at reducing the translational and rotational vibrations of the upper plate when the base is subject to seismic disturbance and the upper plate undergoes impulsive transient motion. Using the experimentally determined model, derivative control scheme is adopted so that the damping of the closed-loop system is effectively increased. It is found that the predicted control performance is in good agreement with the experimental results. Finally, the limit cycle phenomenon due to the controller voltage saturation is compared with the simulation.

• Child Health Nursing Research
• /
• v.15 no.3
• /
• pp.282-290
• /
• 2009

Purpose: The main purpose of this study was to observe the adaptation experience process of adolescents with hematologic malignancies. Methods: The Grounded Theory Method, developed by Strauss & Corbin (1998), was used in this study. The data were collected through in-depth. interviews with 10 adolescents with cancer. Data collection and analysis occurred concurrently. Theoretical sampling technique was used until the data reached saturation. Results: "A deviated life" was verified as the central phenomenon for adolescents with cancer. The adaptation experience process was divided into 3 steps: "Self-confusion", "Reinterpretation", and "Regeneration of self". Through these 3 steps, the adolescents with hematologic malignancies fitted a new life by self-integration. Conclusion: The results of this study provide a frame for individualized nursing intervention strategies in helping with the psychosocial adaptation of adolescents with hematologic malignancies.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.11
• /
• pp.617-624
• /
• 1999

The spiral type thin-film inductor performed in high frequency at 2-5[MHz] range is analyzed by 2-dimensional Finite Element Method(2D FEM). The features of micro thin-film inductor have complicated electromagnetic phenomenon such as skin effect, proximity effect and magnetic saturation. To develope miniatured magnetic device considering these features, it is important to predict the property of the thin film inductor according to design parameter. In this paper, we present the 2D FEM analysis for the spiral type thin film inductor. The characteristics of inductor from point of view of inductance, resistance and quality factor are studied according to design parameter and various pattern construction.

• Corrosion Science and Technology
• /
• v.8 no.6
• /
• pp.232-237
• /
• 2009

Copper tubes are widely used in the distribution systems of drinking water throughout the world because of their excellent corrosion resistance, high thermal conductivity, and ease of fabrication. However, corrosion problems from copper tubes as blue water phenomenon and leakage have been reported appreciably. The effect of pH on the corrosion behavior of copper tube for tap water was investigated by electrochemical voltammetric techniques in synthetic tap water. And the copper corrosion cases were discussed from the viewpoint of factors affecting the corrosion rate such as pH, alkalinity, LSI(Langelier Saturation Index), and concentration of bicarbonate and dissolved carbon dioxide.

• Journal of Magnetics
• /
• v.22 no.2
• /
• pp.196-202
• /
• 2017

The occurrence of ferroresonance in electrical systems including nonlinear inductors such as transformers will bring a lot of malicious damages. The intense ferromagnetic saturation of the iron core is the most influential factor in ferroresonance that makes nonsinusoidal current and voltage. So the nonlinear behavior modeling of the magnetic core is the most important challenge in the study of ferroresonance. In this paper, the ferroresonance phenomenon is investigated in a single phase transformer using the finite element method and considering the hysteresis loop. Jiles-Atherton (JA) inverse vector model is used for modeling the hysteresis loop, which provides the accurate nonlinear model of the transformer core. The steady-state analysis of ferroresonance is done while considering different capacitors in series with the no-load transformer. The accurate results from copper losses and iron losses are extracted as the most important specifications of transformers. The validity of the simulation results is confirmed by the corresponding experimental measurements.

• 한국기계연구소 소보
• /
• s.20
• /
• pp.41-48
• /
• 1990

Electro-pneumatic valves are an electro-mechanical device which convert electric signal into pneumatic flow rate or pressure signal. Recently, the development tendency of electro-pneumatic valve is to make the valve with more compact and less electric power consumption style. To make the valve such as a style, the role of solenoid part is very important. This paper is used in the finite-element method for the purpose of evaluating the magnetic property of solenoid and analyze flux distribution of solenoid theoretically. From flux contour line which is obtained by numerical analysis, it verified that the plunger shape and physical property of solenoid part have influence on saturation phenomenon and leakage of magnetic fluxs. This paper made an experiment on the measurement of dynamic response time and force in order to confirm the propety of analytic result, and confirmed a good agreement between analysis results and experiment results.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.124-125
• /
• 2012

본 논문은 변압기나 리액터의 코어에서 국부적 자속포화 현상을 이용하여 코어에 공극(Air Gap)을 추가하는 효과와 동일한 효과를 거두는 것은 물론 자속포화를 일으키는 전류를 제어함으로써 주코일의 자속이 자속 포화 곡선상에서 선형영역과 비선형영역을 모두 포괄하여 제어할 수 있도록 함을 목적으로 한다. 제안하는 기술적 사상의 효과 및 타당성은 간단한 실험을 통해 증명하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.574-577
• /
• 1999

The chalcogenide glasses of thin films have superior property of the photoinduced anisotrophy(PA). In this study, we observed the phenomenon of Ag polarized photodoping using the irradiation with polarized He-Ne laser light, in the thin film of chalcogenide As/sub 40//Ge/sub 10//Se/sub 15//S/sub 35/ and the double-layer of Ag doped As/sub 40//Ge/sub 10//Se/sub 15//S/sub 35/. The Ag polarized photodoping result in reducing time of saturation anisotrophy and increasing sensitivity of linearly anisotrophy intensity, up to maximum 220%. In the thin films of chalcogenide, the Ag polarized photodoping will be show a capability of new method that suggested more improvement of photoinduced anisotrophy property

• Proceedings of the Optical Society of Korea Conference
• /
• 1989.02a
• /
• pp.20-25
• /
• 1989

The nonlinear, time dependent photon transport equations of Frantz and Nodvik, which describe the amplification of an optical pulse in an active medium, are modified to a simpler equation which describes only the amplification of energy. with this equation, the output energy of the high power YLF(Nd3+)-Phosphate Glass(Nd3+) Laser System is calculated. When the stored energy density Est is 0.10J/㎤, 0.16J/㎤, 0.228J/㎤, and 0.50J/㎤, and with the assumption of uniform population inversion density, the final output energy of this laser system is 5.38J, 176J, 317J, and 283J, respectively. The gain saturation causes distortion of the output beam. This phenomenon is described in detail at the first three rod amplifier systems in the case of E=0.228J/㎤. The peak current and decay time constant of the flashlamps, which are used to obtain population inversion in the active medium, are investigated. The flashlamp driving circuit which has optimum operational performance should have {{{{ SQRT { LC} }} time about 100$\mu$sec.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.3
• /
• pp.25-32
• /
• 2011

The matric suction and volumetric water content of dredging soils obtained from Saemangeum area were measured by the automated Soil-Water Characteristic Curve (SWCC) apparatus under both drying and wetting conditions. Based on the test result, SWCCs of the dredging soils were estimated by the van Genuchten(1980) model. The matric suction of drying process is larger than that of wetting process at a same effective degree of saturation. The suction stresses for various matirc suctions were estimated using Lu and Likos(2006) model and the Suction Stress Characteristic Curves (SSCC) were predicted using the independent parameter of SWCC. The suction stress of drying path was increased and decreased, while the suction stress of wetting path was continuously decreased with increasing the effective degree. Also, the suction stress of drying path is larger than that of wetting path at a same effective degree of saturation. The Hydraulic Conductivity Function(HCF) was also predicted by the van Genuchten(1980) model. The hydraulic conductivity was increased with increasing the volumetric water content. The hydraulic conductivity of drying path is larger than that of wetting path at a same matric suction. According to the results of SWCCs and SSCCs, the hysteresis phenomenon of suction stress or matric suction during both drying and wetting paths was occurred. The main reason of hysteresis phenomenon is a ink bottle effect of water among soil particles.