• 한국음향학회지
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• 제32권4호
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• pp.361-368
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• 2013

진동하는 현의 성질을 나타내는 방법으로 반대 방향으로 진행하는 파가 현과 전송선로에 존재한다는 사실에 기초하여 현은 전송선로에 비유되어왔다. 이러한 비유에서 현의 강역(rigid end)과 변위는 각각 전송선로의 개방회로와 전류로 나타내어졌다. 그러나, 본 연구에서 강역과 변위는 각각 단락회로와 전압에 해당됨이 전송선로의 이론으로부터 밝혀졌고 이를 회로시뮬레이션으로 확인하였다. 이러한 발견에 기초하여 전송선로, 구분적 선형 전류원, 스위치들로 구성된 전송선로 기반 탄현 모델을 제안하였다. 임의로 선택된 지점에서의 전압과 전송선로 끝 극소 부분 양단에서 계산된 전압이 현의 성질을 지배하는 파동방정식의 차분형식(difference form)으로 구한 해당 지점에서 변위와 강역에서의 힘과 일치함을 보임으로서 제안한 모델이 정당함을 증명하였다. 또한, 제안된 모델의 현악기 및 관악기 모델링의 적용성을 제시하였다.

• 한국전기전자재료학회논문지
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• 제27권6호
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• pp.407-416
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• 2014

Five factors are identified, which affect the performance of optical filter: 1) type of optical glass, 2) existence of Fe, 3) photo pic coating type, 4) coating form, and 5) coating thickness. If we consider all the levels of five factors, there are 360 possible candidates. We determined five evaluation criteria, which can be used to evaluate possible candidates. For the performance measures we selected white-state avearge voltage, black-state average voltage, and black-state error rate. And we added economic criterion and quality and maintenance criterion. Through the two-step statistical analysis of white-state avearge voltage, black-state average voltage, and black-state error rates, we selected final four candidates. Based on the five criteria we finally determined optimal optical filter using AHP.

• Journal of Power Electronics
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• 제18권5호
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• pp.1479-1488
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• 2018

Power packet (PP) distribution system distributes power to different loads that share the same distribution cable in a packetized form. When compared with conventional power systems, a PP distribution system (PPDS) can reduce standby power, eliminate Point-of-Load (PoL) power conversion, and intelligently control the load demand from the source side. Due to the absence of PoL conversion, when multiple power sources at different voltage levels and conditioning requirements jointly send power to various loads at different voltage ratings, the generated voltage has an irregular shape. A large filter at each of the load sides is required to reduce such a large voltage ripple. In this paper, a single-inductor, multiple-input-single-output converter structure based multiple-energy-source mixer is proposed. It combines PP generation, maximum power point tracking (MPPT) of renewable energy sources (RESs) and filtering at the source side. To demonstrate the possible renewable energy integration, a PV panel is used as a power source together with other constant voltage sources. The PV power is approximately tracked using the constant voltage method and it is used for each of the PP generations. The proposed PP distribution system is experimentally verified and it is shown that a conventional PI controller is sufficient for stable system operation.

• 센서학회지
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• 제26권3호
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• pp.155-159
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• 2017

The analog-to-digital converter (ADC) is an important component in various fields of sensor signal processing. This paper presents an expandable flash analog-to-digital converter (E-flash ADC) for sensor signal processing using a comparator, a subtractor, and a multiplexer (MUX). The E-flash ADC was simulated and designed in $0.35-{\mu}m$ standard complementary metal-oxide semiconductor (CMOS) technology. For operating the E-flash ADC, input voltage is supplied to the inputs of the comparator and subtractor. When the input voltage is lower than the reference voltage, it is outputted through the MUX in its original form. When it is higher than the reference voltage, the reference voltage is subtracted from the input value and the resulting voltage is outputted through the MUX. Operation of the MUX is determined by the output of the comparator. Further, the output of the comparator is a digital code. The E-flash ADC can be expanded easily.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권1호
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• pp.39-44
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• 1999

The dielectric layers in AC plasma display panel(PDP) are essential to the discharge cell structure, because they protect metal electrodes from sputtering by positive ion bombarding in discharge plasma and form a sheath of wall charges which are essential to memory function of AC PDP. This layer should have high dielectric breakdown voltage, and also be transparent because the luminance of PDP is strongly correlated this layer. In this paper, we discussed the dielectric breakdown voltage and transparency of the dielectric layer under various conditions. As a result, on the $15\mum$ thickness, the minimum dielectric breakdown voltage was 435V and the transmission coefficient was about 80% after $570^{\circ}C$ firing process. It can be proposed that the resonable dielectric thickness in AC PDP is $15\mum$ because it has about 75V margin on the maximum applied voltage.

• 한국정보통신학회논문지
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• 제19권4호
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• pp.903-908
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• 2015

본 연구에서는 비대칭 이중게이트(double gate; DG) MOSFET의 채널 내 도핑분포함수의 변화에 따른 문턱전압이동 현상에 대하여 분석하였다. 반도체소자를 도핑시킬 때는 주로 이온주입법을 사용하며 이때 분포함수는 가우스분포를 나타내고 있다. 가우스분포함수는 이온주입범위 및 분포편차에 따라 형태를 달리하며 이에 따라 전송특성도 변화하게 된다. 그러므로 비대칭 DGMOSFET의 채널 내 도핑분포함수의 변화는 문턱전압에 영향을 미칠 것이다. 문턱전압은 트랜지스터가 동작하는 최소한의 게이트전압이므로 단위폭 당 드레인 전류가 $0.1{\mu}A$ 흐를 때 상단 게이트전압으로 정의하였다. 문턱전압을 구하기 위하여 해석학적 전위분포를 포아송방정식으로부터 급수형태로 유도하였다. 결과적으로 도핑농도가 증가하면 도핑분포함수에 따라 문턱전압은 크게 변하였으며 특히, 고 도핑 영역에서 하단 게이트전압에 따라 이온주입범위 및 분포편차에 의한 문턱전압의 변화가 크게 나타나는 것을 알 수 있었다.

• ETRI Journal
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• 제11권4호
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• pp.98-104
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• 1989

Closed form solution of nonlinear 2-DEG concentration formula is proposed. This allows us to model continuous 2-DEG charge concentration as the function of gate voltage covering subthreshold region of the I-V curves. Comparisons of the Ids-Vgs characteristics and transconductance with the measured data were performed to show the accuracy of the proposed model. This way we have completely closed form I-V characteristics in subthreshold, triode and saturation region incorporating accurate charge control mechanism for HEMTs.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1663-1672
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• 2018

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

• 한국정보통신학회논문지
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• 제18권9호
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• pp.2183-2188
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• 2014

본 연구에서는 비대칭 이중게이트(double gate; DG) MOSFET의 채널 도핑농도 변화에 따른 문턱전압이동 현상에 대하여 분석하였다. 비대칭 DGMOSFET는 일반적으로 저 농도로 채널을 도핑하여 완전결핍상태로 동작하도록 제작한다. 불순물산란의 감소에 의한 고속 동작이 가능하므로 고주파소자에 응용할 수 있다는 장점이 있다. 미세소자에서 필연적으로 발생하고 있는 단채널 효과 중 문턱전압이동현상이 비대칭 DGMOSFET의 채널도핑농도의 변화에 따라 관찰하고자 한다. 문턱전압을 구하기 위하여 해석학적 전위분포를 포아송방정식으로부터 급수형태로 유도하였다. 채널길이와 두께, 산화막 두께 및 도핑분포함수의 변화 등을 파라미터로 하여 도핑농도에 따라 문턱전압의 이동현상을 관찰하였다. 결과적으로 도핑농도가 증가하면 문턱전압이 증가하였으며 채널길이가 감소하면 문턱전압이 크게 감소하였다. 또한 채널두께와 하단게이트 전압이 감소하면 문턱전압이 크게 증가하는 것을 알 수 있었다. 마지막으로 산화막 두께가 감소하면 문턱전압이 증가하는 것을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.408-412
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• 2023

In this paper, in order to analyze high electrical insulation and cooling performance using mineral oil, the liquid insulating oil was changed in electrode shape and distance between electrodes to compare and analyze electrical characteristics according to equal electric field, quasi-equivalent electric field, and unequal electric field. As a result, the breakdown voltages were 36,875 V and 36,875 V in the form of sphere-sphere and plate-plate electrodes with equal electric fields. The breakdown voltage was 31,475 V in the sphere-plate electrode type, which is a quasi-equilibrium field, and the breakdown voltage was 28,592 V, 27,050 V, and 22,750 V in the needle-needle, sphere-needle, and needle-plate electrode types, which are unequal fields. Through this, it is possible to know the difference in breakdown voltage according to the type of electric field. The more equal the field, the higher the breakdown voltage, and the more unequal field, the lower the breakdown voltage. The difference in insulation breakdown voltage could be seen depending on the type of electric field, the insulation breakdown voltage was higher for the more equal electric field, and the insulation breakdown voltage was lower for the more unequal electric field. Also, it was confirmed that the closer the distance between the electrodes, the higher the insulation breakdown voltage, the higher the insulation breakdown current, and the insulation breakdown voltage and the insulation breakdown current were proportional.