• Journal of Advanced Marine Engineering and Technology
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• 제36권6호
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• pp.837-843
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• 2012

비동기 전동기는 여러 분야에서 널리 사용되고 있으며, 특히 전원공급에 비해 많은 전력을 사용하는 전동기의 경우 이를 기동하기 위해서는 다양한 기동방법이 적용되고 있다. 전동기 기동방법은 주로 회전자에 가변저항을 삽입하거나 고정자에 공급하는 전압을 감소시키는 방법이 사용되고 있다. 이와 같이 기동시 가변저항을 변경하거나 전압을 변경하기 위해서는 특정 단계에서 특정한 시간이 필요하게 된다. 이 시간을 스위칭시간이라 부르며, 이 시간을 정확히 파악하는 것은 매우 어려운 부분이다. 이 시간은 전동기의 부하특성이나 그 형식에 따라 변화한다. 따라서 본 논문에서는 전동기와 부하의 수학적 모델의 개발과 설계에 대해서 알아보고, 전동기의 기동에 필요한 스위칭시간을 계산하기 위해 SIMULINK를 활용하여 시뮬레이션을 수행하였다. 시뮬레이션 결과는 다양한 전동기와 부하를 가진 시스템에 가장 적절하고 적용 가능한 기동 시간을 얻는데 활용할 수 있도록 비교 검토되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.326-326
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• 2014

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states [1-3]. We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• Journal of Korea Trade
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• 제26권6호
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• pp.20-40
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• 2022

Purpose - In recent times, the international trade environment has been changing rapidly, centering on the online market. In the post-COVID-19 era, small and medium-sized trading companies are facing the problem of not being properly provided with overseas market research, market trend analysis, and trade-related information. Cloud-based digital trade is being sought as an alternative to solve these problems; however, there is a lack of research on the intention to switch to digital trade among small and medium-sized trading companies. Therefore, this study empirically analyzes the intention to switch to digital trade based on the migration theory, and through this, attempts to identify each factor that affects the intention to switch to digital trade. Design/methodology - In this study, in order to identify factors influencing intention to switch to digital trade and innovation resistance of small and medium-sized trading companies, through previous research on migration theory and the PPM (Push, Pull, Mooring) model, each variable was selected for the purpose of the study. Based on this, a research model was established for the factors affecting switching to digital trade of small and medium-sized trading companies and empirically analyzed. In addition, considering the differences in the innovation propensity and maturity of information infrastructure of trading companies as the recipients of innovation, this study analyzes the moderating effect of the mooring effect and seeks ways to establish specific strategies according to the degree. Findings - As a result of empirical analysis, the pull effect was found to have the greatest influence on intention to switch to digital trade. However, the pull factor was found to have an effect on user resistance, and it was confirmed that it was a factor simultaneously inducing positive and negative consumption behaviors among users. In addition, it was found that the higher the company's innovation propensity, the higher the pull effect's influence on the intention to switch, and analysis showed that the push effect had no influence. In addition, companies with high information infrastructure maturity were expected to have a relatively high level of intention to switch compared to companies with low information infrastructure maturity, and the difference between the two groups was found not to be statistically significant. Originality/value - This study is a timely study in that it demonstrated the effect on the switching to cloud-based digital trade for small and medium-sized trading companies and that the cloud system related to digital trade is in full swing. There are academic implications in that it revealed that the pull effect is an important factor in the intention to switch to cloud service. Practical implications were presented in that small and medium-sized trading companies suggested ways to increase the value of the cloud system for switching to digital trade and a way to increase the switching ratio by minimizing the mooring effect. In addition, the study argues that active institutional support from the government is needed to activate cloud service.

• 한국정보전자통신기술학회논문지
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• 제16권6호
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• pp.434-440
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• 2023

본 논문에서는 교류 서보 전동기 PI 전류제어를 위한 주요 시스템 파라미터인 상저항과 상인덕턴스를 측정하는 방법을 제시한다. 서보 전동기 전류제어를 위한 PI 제어이득은 주요 계통 파라미터인 권선간 저항과 인덕턴스 정보를 활용하여 튜닝하는 자동적 방법이 기본적으로 사용된다. 본 연구에서는 이 두 파라미터를 3상 인버터 제어를 통해 계측하는 방법을 제시한다. 이 제어 및 계측 방법은 3상 인버터를 이용하여 3상 권선에 비례입력 만을 이용하는 스텝 전류제어를 수행하고 그 결과로 얻어진 출력 상전류를 측정함으로써 구현된다. 더불어 이 방법은 권선간 인덕턴스 계측을 위해 특정 스위칭모드에서의 인버터 자연-순환(freewheeling) 전류를 이용한다. 이 인버터 제어를 이용하는 측정 방법은 새로운 추가 계측 회로 및 복잡한 계측 알고리즘을 사용하지 않고 실시간으로 파라미터들을 계측 및 연산할 수 있는 해석적 방법이다. 실제 전동기 제어에 사용되어지는 구동기 회로를 그대로 사용하면서 스위칭소자의 도통저항과 각종 결선 저항을 포함하는 합성 저항 및 인덕턴스를 계측할 수 있는 방법이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.60-63
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• 2001

Investigating electromagnetic emissions of inverter power sources for resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and intermittent operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, snubber circuits and constructional aspects exert a great influence on the conducted emission of resistance welding inverters.

• 한국전기전자재료학회논문지
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• 제26권10호
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• pp.713-719
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• 2013

Power MOSFET operate voltage-driven devices, design to control the large power switching device for power supply, converter, motor control, etc. We have optimal designed planar and trench gate power MOSFET for high breakdown voltage and low on resistance. When we have designed $6,580{\mu}m{\times}5,680{\mu}m$ of chip size and 20 A current, on resistance of trench gate power MOSFET was low than planar gate power MOSFET. The on state voltage of trench gate power MOSFET was improved from 4.35 V to 3.7 V. At the same time, we have designed unified field limit ring for trench gate power MOFET. It is Junction Termination Edge type. As a result, we have obtained chip shrink effect and low on resistance because conventional field limit ring was convert to unify.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• 한국세라믹학회지
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• 제46권3호
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• pp.336-343
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• 2009

Nickel oxide thin films exhibit the resistive switching as a function of applied voltages. The switching phenomena involve low and high resistance states after electroforming. The electrical features are believed to be associated with the formation and rupture of filaments. The set and reset behaviors are controlled by the oxidation and reduction of filaments. The indirect evidence of filaments is corroborated by the presence of nanocrystalline nickel oxides found in high-resolution transmission electron microscopy. The insertion of insulating layers seems to control the current-voltage characteristics by preventing the continuous formation of conductive filaments, potentially leading to artificial control of resistive behaviors in NiO-based systems.

• Journal of Power Electronics
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• 제13권2호
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• pp.250-255
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• 2013

This paper proposes an optimal current distribution method of dual-rotor brushless DC machines (DR-BLDCMs) which have inner and outer surface-mounted permanent-magnet rotors. The DR-BLDCM has high power density and high torque density compare to the conventional single rotor BLDCM. To drive the DR-BLDCM, dual 3-phase PWM inverters are required to excite the currents of a dual stator of the DR-BLDCM and an optimal current distribution algorithm is also needed to enhance the system efficiency. In this paper, the copper loss and the switching loss of a DR-BLDCM drive system are analyzed according to the motor parameters and the switching frequency. Moreover, the optimal current distribution method is proposed to minimize the total electrical loss. The validity of the proposed method was verified through several experiments.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권1호
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• pp.23-33
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• 2002

A hysteresis control is widely used to control output current of inverter. A hysteresis bandwidth is affected by system parameters such as source voltage, device on/off time, load inductance and resistance. The frequency limiter is used to protect switching devices overload. In the conventional hysteresis controller, a lock-out circuit with D-latch and timer is used to device protection circuit. But switching delay time and harmonic components are appeared in output current. In this paper the performance of lock-out circuit is tested, and new circuit for switching device fault protection is proposed ad it's performance is simulated.