• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.90-100
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• 2015

Green technologies such as renewable energy resources, Electric Vehicles and Plug-in Hybrid Electric Vehicles (EVs/PHEVs), electric locomotives, etc. are continually increasing at the existing power network especially distribution levels, which are Medium Voltage (MV) and Low Voltage (LV). It can be noted that the increasing level of green technologies is driven by the reduction emission policies of carbon dioxide ($CO_2$). The green technologies can affect the quality of power, and hence its impacts of are analysed. In practical, the environment such as wind, solar irradiation, temperature etc. are uncontrollable, and therefore the output power of renewable energy in that area can be varied. Moreover, the technology of the EVs/PHEVs is still developed in order to improve the performance of supply and driving systems. This means that these developed can cause harmonic distortion as the control system is mostly used power electronics. Therefore, this paper aims to analyse the voltage variation and harmonic distortion in distribution power network in urban area in Europe due to the combination between wind turbine, hydro turbine, photovoltaic (PV) system and EVs/PHEVs. More realistic penetration levels of SSDGs and EVs/PHEVs as forecasted for 2020 is used to analyse. The dynamic load demands are also taken into account. In order to ensure the accurate of simulation results, the practical parameters of distribution system are used and the international standards such as Institute of Electrical and Electronics Engineers (IEEE) standards are also complied. The suggestion solutions are also presented. The MATLAB/Simulink software is chosen as it can support complicate modelling and analysis.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.845-848
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• 2009

전력용반도체(Power Management IC)는 전력의 변환이나 제어용으로 최적화되어 있는 전력장치용 반도체 소자로서 전자기기에 들어오는 전력을 그 전자기기에 맞게 변경하는 역할을 하며, 일반 반도체에 비해서 고내압화, 큰 전류화, 고주파수화 되어 있다. 전력용반도체는 전기가 쓰이는 제품에는 다 들어가며, 자동차, 공업제품, 컴퓨터와 주변기기, 통신, 가전제품, 모바일 기술, 대체 에너지 등에 대한 수요 증가가 시장의 성장을 촉진한다. 전력용반도체 개발을 통해 대일무역적자 해소 기여, 취약한 비메모리 산업의 육성을 통한 반도체산업의 균형발전, 신성장동력 창출을 통한 미래 경제발전을 도모할 수 있다. 본 고에서는 반도체 부문의 미래 유망품목인 전력용반도체의 필요성 및 중요성, 시장현황 및 전망을 중심으로 살펴보고 결론에서 정책적 시사점을 도출하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.673-676
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• 2003

In this paper, we designed the embedded system used for wireless LAN communication. Embedded system kernel is made from general linux kernel 2.4.18 by applying the ARM patch (2.4.18-rmk7) and the SA1100 patch(2.4.18-rmk7), then porting board level suitable to target system. The SA-1110 PCMCIA interface provides controls for one PCMCIA card slot with a PSKTSEL pin for support of a second slot. The embedded system requires external logic to complete the PCMCIA socket interface. For dual-voltage support, level shifting buffers are required for all SA-1110 input signals. Hot insertion capability requires that each socket be electrically isolated from each other, and from the remainder of the memory system. embedded system is for socket services approaching PCMCIA socket, detecting number of sockets, sensing insertion and removal, and applying power. It also provides interface with Card services. Embedded system supports Host driver for lucent chips that is installed orinoco driver cross compiled. The meaning can say that is doing wireless LAN communication through wireless LAN in imbedded system.

• Structural Monitoring and Maintenance
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• 제10권3호
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• pp.261-281
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• 2023

Magnetic flux sensors are commonly used in monitoring the cable force, but the application of the sensors in large diameter non-closed Galfan cables, as those adopted in Yueqing Gymnasium which is located in Yueqing City, Zhejiang Province, China and is the largest span hybrid space structure in the world, is seldom done in engineering. Based on the construction of Yueqing Gymnasium, this paper studies the cable tension monitoring using the magnetic flux method across two stages, namely, the pre-calibration stage before the cable leaves the rigging factory and the field tension formation stage of the cable system. In the pre-calibration stage in the cable factory, a series of 1:1 full-scale comparative tests were carried out to study the feasibility and relability of this kind of monitoring method, and the influence on the monitoring results of charging and discharging voltage, sensor location, cable diameter and fitting method were also studied. Some meaningful conclusions were obtained. On this basis, the real-time cable tension monitoring system of the structure based on the magnetic flux method is established. During the construction process, the monitoring results of the cables are in good agreement with the data of the on-site pressure gauge.The work of this paper will provide a useful reference for cable force monitoring in the construction process of long-span spatial structures.

• The Korean Journal of Physiology
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• 제28권2호
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• pp.215-224
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• 1994

The presence of a calcium current $(i_{Ca^{2+}})$ passed via a specific channel was examined in the unfertilized hamster egg using the whole-cell voltage clamp technique. Pure inward current was isolated using a $Ca^{2+}-rich$ pipette solution containing 10 mM TEA. This current was independent of external $Na^+$ and was highly sensitive to the $Ca^{2+}$ concentration in the bathing solution, indicating that the inward current is carried by $Ca^{2+}$. The maximal amplitude was $-4.12{\pm}0.58nA\;(n=12)$ with 10mM $Ca^{2+}$ at -3OmV from a holding potential of -8OmV. This current reached its maximum within 20ms beyond -3OmV and decayed rapidly with an inactivation time constant $({\tau})$ of 15ms. Activation and inactivation of this $i_{Ca^{2+}}$ was steeply dependent on the membrane potential. The $i_{Ca^{2+}}$ began to activate at the lower voltage of -55 mV and reached its peak at -35 mV, being completely inactivated at potentials more positive than -40 mV. These result suggest that $i_{Ca^{2+}}$ in hamster eggs passes through channels with electrical properties similar to low voltage-activated T-type channels. Other results from the present study support this suggestion; First, the inhibitory effect of $Ni^{2+}\;(IC_{50}=13.7\;{\mu}M)$ was more potent than $Cd^{2+}\;(IC_{50}=123\;{\mu}M)$. Second, $Ba^{2+}$ conductance was equal to or below that of $Ca^{2+}$. Third, $i_{Ca^{2+}}$ in hamster eggs was relatively insensitive to nifedipine $(IC_{50}=96.6\;{\mu}M)$, known to be a specific t-type blocker. The physiological role of $i_{Ca^{2+}}$ in the unfertilized hamster eggs remains unclear. Analysis from steady-state inactivation activation curves reveals that only a small amount of this current will pass in the voltage range $(-70{\sim}-30\;mV)$ which partially overlaps with the resting membrane potential. This current has the property that it can be easily activated by a weak depolarization, thus it may trigger a certain kind of a intracellular event following fertilization which may cause oscillations in the membrane potential.

• 멤브레인
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• 제31권5호
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• pp.351-362
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• 2021

전 바나듐 레독스 흐름 전지(VRFB)는 유망한 대용량 에너지 저장 기술 중 하나이다. 이온교환막은 VRFB의 충·방전 성능 및 내구성을 좌우하는 핵심 구성 요소이다. 본 연구에서는 기존 탄화수소계 이온교환막의 단점을 보완하기 위해 우수한 물리적 및 화학적 안정성을 갖는 다공성 폴리테트라플루오로에틸렌(PTFE) 지지체의 세공에 불소부가 포함된 탄화수소계 이오노머를 충진하는 방식으로 세공충진 음이온교환막(PFAEMs)을 제조하였다. 얇은 다공성 PTFE 지지체의 사용으로 전기적 저항을 현저히 낮출 수 있었으며 PTFE 지지체의 사용과 더불어 충진 이오노머에 불소부를 도입함으로써 막의 산화 안정성을 크게 향상시킬 수 있었다. 충·방전 성능 평가 결과, PFAEM에 불소부의 함량이 증가할수록 높은 전류 효율을 나타내었으며 낮은 전기적 저항으로 상용막 대비 우수한 전압 효율 및 에너지 효율을 보였다. 또한, 산화 안정성 및 충·방전성능의 관점에서 소수성 PTFE 지지체의 사용이 더 바람직함을 확인하였다.

• 한국분말재료학회지
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• 제22권4호
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• pp.240-246
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• 2015

Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at $4^{\circ}C$. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.

• 청정기술
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• 제29권4호
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• pp.255-261
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• 2023

파워반도체는 전력의 변환, 변압, 분배 및 전력제어 등을 감당하는데 사용되는 반도체이다. 최근 세계적으로 고전압 파워반도체의 수요는 다양한 산업분야에 걸쳐 증가하고 있는 추세이며 해당 산업에서는 고전압 IGBT 부품의 최적화 연구가 절실한 상황이다. 고전압 IGBT개발을 위해서 wafer의 저항값 설정과 주요 단위공정의 최적화가 완성칩의 전기적특성에 큰 변수가 되며 높은 항복전압(breakdown voltage) 지지를 위한 공정 및 최적화 기술 확보가 중요하다. 식각공정은 포토리소그래피공정에서 마스크회로의 패턴을 wafer에 옮기고, 감광막의 하부에 있는 불필요한부분을 제거하는 공정이고, 이온주입공정은 반도체의 제조공정 중 열확산기술과 더불어 웨이퍼 기판내부로 불순물을 주입하여 일정한 전도성을 갖게 하는 과정이다. 본 연구에서는 IGBT의 3.3 kV 항복전압을 지지하는 ring 구조형성의 중요한 공정인 field ring 식각실험에서 건식식각과 습식식각을 조절해 4가지 조건으로 나누어 분석하고 항복전압확보를 위한 안정적인 바디junction 깊이형성을 최적화하기 위하여 TEG 설계를 기초로 field ring 이온주입공정을 4가지 조건으로 나누어 분석한 결과 식각공정에서 습식 식각 1스텝 방식이 공정 및 작업 효율성 측면에서 유리하며 링패턴 이온주입조건은 도핑농도 9.0E13과 에너지 120 keV로, p-이온주입 조건은 도핑농도 6.5E13과 에너지 80 keV로, p+ 이온주입 조건은 도핑농도 3.0E15와 에너지 160 keV로 최적화할 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권8호
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• pp.399-403
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• 2006

An accurate constant output voltage provided by the analog memory cell may be used by the low power oscillator to generate an accurate low frequency output signal. This accurate low frequency output signal may be used to maintain long-term timing accuracy in host devices during sleep modes of operation when an external crystal is not available to provide a clock signal. Further, incorporation of the analog memory cell in the low power oscillator is fully implementable in a 0.35um Samsung standard CMOS process. Therefore, the analog memory cell incorporated into the low power oscillator avoids the previous problems in a oscillator by providing a temperature-stable, low power consumption, size-efficient method for generating an accurate reference clock signal that can be used to support long sleep mode operation.

• 전기학회논문지P
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• 제66권4호
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• pp.267-273
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• 2017

In recent years, there is an increasing demand for DC microgrid because the digital load due to DC increases and the efficiency of the distribution system increases due to loss of conversion losses and conversion stages due to reactive power compared to AC distribution. Currently, with the support of the KEPRI, the development of an electronic large-capacity circuit breaker for DC distribution protection, which has been underway since 2016, is proceeding. In this paper, as a part of this project, we modeled the DC microgrid connected with PV using PSCAD. The converter station, AC/DC converter control, PV and MPPT controller are designed. In order to evaluate the performance of the modeled DC microgrid, it is examined whether the voltage is adjusted according to the load variation.