• 전기학회논문지
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• 제63권8호
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• pp.1098-1103
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• 2014

This study deals with the development of an electrofusion welding machine that is capable of joining plastic pipes using a recently developed electrofusion fitting. This fitting has built-in conductive plastics that are used to weld the joint together as a heating element. In order to explain the mechanism of the new machine, 1) the resistance characteristics of the heating element were explained, 2) the method of electric welding that uses the electrofusion fitting was described, and 3) the method of power supply based on controlling the firing angle was explained. A control system for an intelligent electrofusion welding machine was proposed. This system has the ability to recognize the diameter of an electrofusion fitting using a lookup-table based on the difference of resistance curves according to fitting types, and it is able to weld the fittings regardless of the ambient temperature. A new algorithm was developed to control the power of electric welding through the recognition of feature points from the resistance curve of the heating element. In order to evaluate the performance of the developed welding machine, tests involving the welding of 16 mm- and 20 mm-type fittings were carried out. Examining the welding results, we concluded that the proposed welding machine will offer high productivity and reliability in the field of electrofusion welding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1088-1090
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• 2001

In general, Power SCR(Silicon Controlled Rectifier) is most widely used in Power Plant as well as Industrial field. It has been controlled and operated according to its own control method. Especially, in case of Power plant, it plays a major role in AVR(Automatic Voltage Regulator) or electro chlorination control circuits. Generally, they used in Analog control system at above field. But each SCR current value is different because of load unbalance or switching characteristic variations, it may cause power plant unit trip or system disorder according to SCR element burn out or bad operating condition. Therefore, in this paper a development of 3 phase current balance control unit is described, it gets over the past analog control system limit, uses DSP(Digital signal processor) had high speed response, controls SCR gate firing angle for 3 phase current balance.

• Journal of Magnetics
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• 제19권4호
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• pp.357-364
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• 2014

This study examined effect of a transcranial magnetic stimulation device with a commercial-frequency approach on the neuronal cell death caused ischemia. For a simple transcranial magnetic stimulation device, the experiment was conducted on an ischemia induced rat by transcranial magnetic stimulation of a commercial-frequency approach, controlling the firing angle using a Triac power device. The transcranial magnetic stimulation device was controlled at a voltage of 220 V 60 Hz and the trigger of the Triac gate was varied from $45^{\circ}$ up to $135^{\circ}$. Cerebral ischemia was caused by ligating the common carotid artery of male SD rats and reperfusion was performed again to blood after 5 minutes. Protein Expression was examined by Western blotting and the immune response cells reacting to the antibodies of Poly ADP ribose polymerase in the cerebral nerve cells. As a result, for the immune response cells of Poly ADP ribose polymerase related to necrosis, the transcranial magnetic stimulation device suppressed necrosis and had a protective effect on nerve cells. The effect was greatest within 12 hours after ischemia. Therefore, it is believed that in the case of brain damage caused by ischemia, the function of brain cells can be restored and the impairment can be improved by the application of transcranial magnetic stimulation.

• 대한기계학회논문집B
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• 제26권12호
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• pp.1639-1645
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• 2002

Micro engine that includes Micro scale combustor is fabricated. Design target was focused on the observation of combustion driven actuation in MEMS scale. Combustor design parameters are somewhat less than the size recommended by feasibility test. The engine structure is fabricated by isotropic etching of the photosensitive glass wafers. Electrode formed by electroplating of the Nickel. Photosensitive glass can be etched isotropically with almost vertical angle. Bonding and assembly of structured photosensitive glass wafer form the engine. Combustor size was determined to be 1 mm scale. Movable piston is engraved inside the wafer. Ignition was done by nickel spark plug which was electroplated with thickness of 40 ${\mu}{\textrm}{m}$. The wafers were bonded by epoxy that resists high temperature. In firing test due to the bonding method and design tolerance pressure buildup by reaction was not confirmed. But ignition, flame propagation and actuation of micro structure from the reaction was observed. From the result basement of design and fabrication technology was obtained.

• Journal of Magnetics
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• 제19권2호
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• pp.197-204
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• 2014

A transcranial magnetic stimulation device is a complicated appliance that employs a switching power device designed for discharging and charging a capacitor to more than 1 kV. For a simple transcranial magnetic stimulation device, this study used commercial power and controlled the firing angle using a Triac power device. AC 220V 60 Hz, the power device was used directly on the tanscranial magnetic stimulation device. The power supply device does not require a current limiting resistance in the rectifying device, energy storage capacitor or discharge circuit. To control the output power of the tanscranial magnetic stimulation device, the pulse repetition rate was regulated at 60 Hz. The change trigger of the Triac gate could be varied from $45^{\circ}$ to $135^{\circ}$. The AVR 182 (Zero Cross Detector) Chip and AVR one chip microprocessor could control the gate signal of the Triac precisely. The stimulation frequency of 50 Hz could be implemented when the initial charging voltage Vi was 1,000 V. The amplitude, pulse duration, frequency stimulation, train duration and power consumption was 0.1-2.2T, $250{\sim}300{\mu}s$, 0.1-60 Hz, 1-100 Sec and < 1 kW, respectively. Based on the results of this study, TMS can be an effective method of treating dysfunction and improving function of brain cells in brain damage caused by ischemia.

• 한국자기학회지
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• 제2권1호
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• pp.69-74
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• 1992

본 논문에서는 커패시터로 구동되는 공진 유도형 코일건의 속도 및 에너지 전달 특성을 해석했다. 유도형 코일건은 설치가 자유롭고, 기계적 마모가 적고, 반복사용이 가능하며, 전달되는 힘이 피투사체의 표면에 고르게 분포한다는 장점을 가지고 있다. 특성해석을 위해 등가회로를 구성 하여 회로방정식과 운동방정식을 유도하고, 이 방정식들을 Runge-Kutta 방법을 사용하여 수치적으 로 풀었다. 그리고 구동회로의 공진주파수 및 커패시터의 충전전압에 대한 에너지 전달율을 구했으 며, 또한 피투사체의 초기위치와 도전율, 구동회로의 점호각, 충전전압 및 구동코일의 저항 각각에 대한 피투사체의 포구속도의 변화를 구하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.569-570
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• 2006

Effects of the evaporation rate of MgO films using electron beam were investigated on the MgO properties and the discharge characteristics of the plasma display panel (PDP). The evaporation rate was changed from $3{\AA}$/sec to $15{\AA}$/sec at a substrate temperature of $300^{\circ}C$. MgO properties such as crystal orientation, surface roughness, contact angle, and film structure were inspected using XPS, AFM, drop shape analysis and SEM. We also studied the relation between MgO properties and PDP discharging characteristics. The minimum firing voltage and maximum efficacy were obtained at evaporation rate of $5{\AA}$/sec. In the MgO film deposited at $5{\AA}$/sec, (200) orientation was most intensive and surface roughness was minimum.

• 전기학회논문지
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• 제65권3호
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• pp.511-519
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• 2016

This paper is proposed control algorithm for the using thyristor of the parallel dual converter for Urban railway power supply in order to return the regenerative power generated by regenerative braking in urban railway train. Conventional control algorithm of Thyristor dual converter for urban railway power supply has voltage variation within a control range of hysteresis band. The purposed control algorithm of the parallel thyristor dual converter is to maintain a constant voltage without voltage variation in accordance with variable load through the Sequential mode change. And the control algorithm need calculating optimum initial firing angle to consider magnitude of the load current slope. For this purpose, Proposed algorithm for sequential conversion mode of the dual converter was verified by applying for the simulation.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.125-130
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• 2004

Experimental study on combustion characteristics of double swirl coaxial injectors has been conducted for the assessment of critical injector design parameters. A reusable, unielement thrust chamber has been fabricated with a water-cooled copper nozzle. Two principle design parameters, a swirl angle and a recess length, have been investigated through hot firing tests for the understanding of their effects on high pressure combustion. Clearly, both parameters considerably affect the combustion efficiency, dynamics and hydraulic characteristics of an injector. Internal mixing of propellants in a recess region increases combustion efficiency along with the increase of a pressure drop required for flowing the same amount of mass flow rates. It is concluded that pressure buildup due to flame can be released by the increase of LOx flow axial momentum or the reduction of a recess length. Dynamic pressure measurements of the thrust chamber show varied dynamic behaviors depending on injector configurations.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.359-365
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• 2012

In the soft recoil system, the recoiling parts are initially accelerated to the forward direction. These parts are returned to original position by the firing with intial acceleration speed. The latch of the soft recoil system keeps the high impact load when the recoil parts were recuperated to the forward direction. In this study, the latch of soft recoil system using the ADAMS program was analyzed. The optimal operation parameters were found that max. angle and expansion length of latch was $50^{\circ}$, 180 mm respectively. Dynamic structural analyses of model cases were performed using finite element model. The max. stress and deflection of latch was 230 MPa and 0.45 mm respectively.