• Korean Journal of Metals and Materials
• /
• v.47 no.6
• /
• pp.338-343
• /
• 2009

The purpose of this study is to make the tantalum powder for solid electrolyte capacitor with SHS (self-propagating high-temperature synthesis) process. Raw materials for manufacturing Ta powder were used $Ta_{2}O_{5}$, Mg and NaCl. While progressing SHS process, $Ta_{2}O_{5}$ powder was reduced by Mg powder. The combustion temperature and velocity were easily controled by the varying mole ratio of NaCl, Mg and initial reaction pressure. In the case of only using NaCl as an inorganic agent, the shape is unagglomerated and has high surface area. whereas we were given the powder which has good net structure by the addition of excessive Mg as a diluent.

• Journal of the Korea Safety Management & Science
• /
• v.23 no.3
• /
• pp.103-113
• /
• 2021

As the use of capacitors in electrical appliances and electrical control circuits increases, the related electrical fire is increasing. There are various parts such as resistors, coils, and capacitors that make up an electric circuit. Among them, the ignition of a capacitor with a temporary charging function is closely related to the structural characteristics of the capacitor. Capacitors can explode due to various reasons, and the high heat generated when they explode ignites the inflammable dielectric, which in turn burns the inflammable materials such as the surrounding electric wires and spreads into a fire. In this paper, the ignition mechanism is studied by conducting a reenactment experiment on the various probabilities that can be ignited in an electric capacitor, and the prevention measures to be applied to the fire prevention are presented.

• Korean Journal of Metals and Materials
• /
• v.48 no.4
• /
• pp.326-334
• /
• 2010

Porous and net-shaped tantalum powder for a capacitor was formulated in a SHS (self-propagating high-temperature synthesis) process. However, this powder, which has weak strength among its particles and low flow ability, cannot be used for a capacitor. Therefore, this powder was sintered in a high-vacuum furnace to increase agglomeration to improve the flow ability, bonding strength among the particles, and shrinkage during pellet sintering. Finally, it was deoxidated with 2 wt% Mg powder to remove the increased surface oxygen that arose during the sintering process. The final product was analyzed in terms of its chemical and physical properties and was compared with a commercial powder used by a capacitor manufacturer.

• Polymer(Korea)
• /
• v.33 no.1
• /
• pp.79-83
• /
• 2009

Thin electric insulation layers were coated on aluminum plates and aluminum condenser cases by plasma polymerization of HMDSO+$O_2$. Electric resistances of the films were higher than 1.0 M$\Omega$ if they are thicker than 0.5 ${\mu}m$ independently of the type of films but their surface morphologies and adhesion strengths were dependent on the process conditions. Deposition rate and adhesion strength of the films were dependent on $O_2$/HMDSO flow ratio and discharge power. The best result was obtained at $O_2$/HMDSO flow ratio of 4 and discharge power of 60 W. Adhesion strength could also be highly improved if aluminum was pre-treated in boiling water for 30 min through the formation of Al-O-Si bonding between the film and the aluminum surface. The coated films showed excellent chemical and thermal resistances.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.9 no.1
• /
• pp.37-46
• /
• 1995

Along with the recent trend of complexity and long distance transmission in power system, dynamic analysis of stability considering the load characteristics is an important subject. In this paper, the influence of the induction motor loads on the power system voltage is investigated. The influence of the inductive load ratio and the inertia of induction motor on the voltage response of the power system are examined, and in the case of the high percentage of the induction motor load, induction motors in the power system can lead to transient voltage instability even under the system condition such as switching operation. The application of static condenser(SC) to prevent the transient voltage instability is introduced.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.6
• /
• pp.495-501
• /
• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.82-82
• /
• 2009

현재 국내에는 많은 가구들이 전기를 사용하고 있다. 아파트, 주택에 들어가는 전기 시스템들이 많이 발전하였지만 뜻하지 않은 사고로 인해 정전이 되는 경우가 있다. 정전시에는 아파트 같은 경우는 비상등, 엘리베이터 등 최소한의 장치만이 작동하도록 되어있다. 그러므로 각 세대에는 전기가 들어가지 않는다. 우리나라 경우에는 태풍이나 여름 같은 경우에는 전기를 많이 사용하기 때문에 발전기가 과부화 걸리는 현상이 생기기도 한다. 장기간 정전시에 가장 문제가 되는 기기는 냉장고, 전등이 될 것이다. 냉장고 같은 경우는 음식들이 상하게 되고, 전등 같은 경우에는 밤에 활동하는데 지장을 주게 된다. 따라서 본 논문에서는 정전시에는 자동적으로 비상발전기의 전원을 사용하고, 상시에는 다시 한전의 전원을 사용하게 하는 초소형 자동 스위칭 전원 모듈을 설계 제작한 논문이다. 설계된 스위칭 모듈에 대해서 시뮬레이션한 결과 예상한대로 비상시에 자동적으로 스위칭되는 결과를 알 수 있었다.

• Journal of Sensor Science and Technology
• /
• v.8 no.1
• /
• pp.16-23
• /
• 1999

When a moving piezoelectric transducer detects an object in water, its receiving sensitivity is attenuated by Doppler effect. In this paper, a method for compensating the effect is suggested by using a newly designed condenser of which capacitance is varied according to the moving speed of the transducer. Using the method, the receiving resonant frequency of the transducer can be changed automatically. As a result, there is good agreement between the results of experiment and those of calculation. It is confirmed that the response sensitivity degradation of transducers due to Doppler effect can be compensated in the range of $1{\sim}10^m/_s$ moving speed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.210-215
• /
• 2003

A terminal pin, which is a part of high-voltage capacitors, has a head section of plate-shaped geometry with 0.8 thickness. The current manufacturing process, in which the head section is welded on the body part, has given wide deviations of part qualities such as geometrical accuracy, mechanical strength and electrical stability. In this paper, a cold forging process sequence was designed in order to produce the terminal pin as one piece. The plate-shaped head section requires an upsetting in the lateral direction of a cylindrical billet, which is followed by a blanking process. The deformed geometry of the upsetting, however, could not be predicted precisely by intuition since metal flows of an axial and a lateral direction of the cylindrical billet would occur simultaneously. Therefore, the geometry of the initial billet was determined by three dimensional finite element analysis in order to avoid defects in blanking process and intermediate forging processes were designed by applying design rules and two dimensional FE analysis. In addition, cold forging tryouts were conducted by using the die sets which were manufactured based on the designed process sequence.

• Transactions of Materials Processing
• /
• v.23 no.6
• /
• pp.386-391
• /
• 2014

In the current study, Al-Mn-Zn alloys are strip-cast and used as the base alloy for the core of aluminum clad sheets used in automotive condenser fins. Transition elements such as Cu and Cr are added to the base core alloy in order to improve the properties of the clad sheets. The AA4343/Al-Mn-Zn-X(X: Cu, Cr)/AA4343 clad sheets are fabricated by roll bonding and further cold-rolled to a thickness of 0.08 mm. Clad sheets were intermediately annealed during cold rolling at $450^{\circ}C$ in order to obtain 40% reduction at the final thickness. Tensile strength and sag resistance of the clad sheets are improved by Cu additions to the core alloy, while corrosion resistance is also increased. Cr-additions to the clad sheets enhance sag resistance and provide low enough corrosion, although tensile strength is not improved. The effect of Cu and Cr additions on the properties of the clad sheets is elucidated by microstructural analysis.