• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.333-344
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• 2018

This proposed paper aims for the high efficiency contactless power transfer in household dc power distribution. A 300 W five-level diode clamped multi-level converter with 300 Vdc input dc link bus is employed for the power transferring task and the output voltage range is controlled at 48 Vdc. The inner and outer solenoid coils are used for inductive power transfer (IPT) transformer with the 200 kHz switching frequency for designed power density. Therefore, to achieve the converter efficiency above 95%, the LLC series resonant with fundamental harmonic analysis (FHA) and the calculated switching angles are used as an optimized tool for designing the system resonant tank. The validations of this approached topology are illustrated in both MATLAB/Simulink simulation and implementation.

• 지식경영연구
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• 제22권3호
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• pp.235-252
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• 2021

정보통신기술의 발달과 코로나19는 호텔산업에 이례적인 변화를 불러일으켰고, 호텔 고객들의 서비스 로봇과 같은 비대면 서비스에 대한 수요가 급증하였다. 이에 본 연구는 혼합분석기법을 적용하여 호텔 고객의 비대면 서비스에 대한 인식을 조사하고자 한다. 구체적으로 본 연구는 구조방정식모형을 통해 변수들간의 상관관계를 파악하였으며, 나아가 퍼지셋 질적 비교 분석 기법을 적용하여 비대면 서비스를 제공하는 호텔 이용의도를 형성하는 변수들의 패턴을 도출하였다. 분석결과, 서비스 경험 공동창출, 즐거움, 개인화 그리고 신뢰가 비대면 서비스 이용욕구를 거쳐 이용의도에 유의한 영향을 미치는 것으로 나타난 반면에, 퍼지셋 질적 비교 분석 방법에서는 도출된 모든 패턴에서 즐거움이 핵심 요인으로 도출되었다. 이러한 분석결과를 토대로 본 연구는 호텔 고객의 비대면 서비스에 대한 심도 있는 이해를 위한 학술적 근거를 제시하였으며, 호텔 매니저들에게 위드 코로나 시대에 비대면 서비스 전략에 대한 구체적인 가이드라인을 제시하였다.

• 한국항행학회논문지
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• 제11권3호
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• pp.337-342
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• 2007

본 논문에서는 현재 국내 ETCS(Electrical Toll Collection System)에 적용될 예정에 있는 후불식 지불 방식에 있어서 수행해야할 전자 신용카드(EMV) 처리절차를 제안한다. 현재 국내에서는 한국도로공사의 하이패스, 터치패스 시스템이 비접촉식 ETCS로 운영되고 있으며, 현재의 운영 방식은 일종의 전자화폐 개념의 선불(pre-paid)식이다. 이에 반해 후불(credit)식은 신용카드 기반의 지불을 수행함으로써 미리 지불할 필요가 없다는 장점이 있다. 현재 국내의 ETCS에 후불식의 도입이 준비 중에 있으며, 본 논문에서는 이러한 후불식 지불에서 고려해야 할 EMV 처리 방식을 제안한다.

• 한국초전도ㆍ저온공학회논문지
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• 제16권3호
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• pp.21-25
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• 2014

As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz.

• 센서학회지
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• 제14권2호
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• pp.78-84
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• 2005

A contactless recharging device for totally implantable middle ear systems has been designed as a pillow type that the user can recharge the implanted battery with taking a rest. The proposed device uses the electromagnetic coupling between the transmitting coil and the receiving coil. To supply sufficient power for the implanted circuits, each coil uses LC resonance and the implanted device uses voltage doubler. A power MOSFET is used for switching the DC voltage of LC parallel circuit and the switching frequency demands on a programmable frequency generator which is controlled by microcontroller. In order to improve the electromagnetic coupling efficiency at specific positions of coil which may vary with the displacement of head, the optimal location of receiving coil was studied, and the 5 transmitting coils in a pillow for recharging the implant module was designed. From such a recharging experiment, it was found that the proposed device could provide the sufficient operating voltage within the distance of 4 cm between pillow and the implanted device.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.535-538
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• 2011

The electromodulation methods of photoreflectanceand the related technique of contactless electroreflectance(CER) are valuable tools in the evaluation of important device parameters for structures such as heterojunction bipolar transistors, pseudomorphic high electron mobility transistors, and quantum dots(QDs). CER is a very general principle of experimental physics. Instead of measuring the optical reflectance of the material, the derivative with respect to a modulating electric field is evaluated. This procedure generates sharp, differential-like spectra in the region of interband (intersubband) transitions. We conduct electric-optical studies of both GaAs layers and InAs selfassembled QDs grown by molecular beam epitaxy. Strong GaAsbandgap energy is measured in both structures. In the case of lnAs monolayers in GaAs matrices, the strong GaAsbandgap energy is caused by the lateral quantum confinement.

• Journal of Korean Vacuum Science & Technology
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• 제6권4호
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• pp.139-142
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• 2002

Contactless electroreflectance measurements at room temperature were used to determine the bandgap energies of Zn$_{1-x}$ Mg$_{x}$O thin films grown by metal-organic vapor phase epitaxy. It is found that the bandgap energy increases monotonically with the Mg composition x, up to the highest composition measured (x=0.45). The obtained correlation between the bandgap energy and the Mg composition can be used in the analysis of the electronic structure of ZnO/Zn$_{1-x}$ Mg$_{x}$O heterostructures at room temperature.ature.

• 한국IT서비스학회지
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• 제20권3호
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• pp.27-40
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• 2021

There have been a series of mixed reviews on the 'untact work' which was implemented for the safety of the organizational members from Covid-19. This study reports a follow-up study with a quantitative approach to issues identified by in-depth interviews with workers and managers who have experiences in work from home. To compare the views of workers and managers on untact work, 264 workers and 141 managers were surveyed. An analysis of agreement, congruency, and accuracy on the basis of the co-orientation model shows that workers are more positive about the untact work than managers and that managers are found to have a negative perception on untact work. This seems to be a burden on workers. More specifically, managers and workers show significant perception gaps on the issues of unfair evaluation and work-life balance. The results imply that organizations need to make efforts to minimize the perception gaps between workers and managers. This would bring about benefits from untact work.

• Journal of Smart Tourism
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• 제3권2호
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• pp.23-36
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• 2023

Due to the phenomenon of aging, a new consumer segment known as the "new-silver generation" is emerging. Unlike the previous silver generation, this generation possesses significant economic power and consuming willingness, attracting attention from consumer goods companies. However, both the new-silver generation and the elderly face challenges in adopting contactless or self-service technologies such as self-order kiosks, resulting in negative reactions. Therefore, this study aims to investigate the attitude and response of the newsilver generation towards kiosks, as well as the factors influencing their resistance to such technology. By applying theoretical perspectives from the innovation resistance model, technostress theory, and the value-based model, this study identifies influencing factors for innovation resistance among the new-silver generation when using contactless technologies implemented in fast-food restaurants. The findings indicate that a lower awareness of new technologies and services corresponds to decreased adoption resistance, while a higher perceived value leads to more positive behaviors and attitudes among the new-silver generation utilizing kiosks at fast-food restaurants.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.514-522
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• 2014

A new type of high precision electromagnetic suspension (EMS) which can support heavy tray along long stroke rail is proposed in this paper. Compared with the conventional EMS, the suggested moving-core typed EMS has the levitation electromagnets (EMs) on the fixed rail. This scheme has high load capability caused by iron-core and enables simple tray structure. Also it does not have precision degradation caused by heat generation from EMs, which is a drawback of conventional EMS. With these merits, the proposed EMS can be an optimal contactless linear bearing in next generation flat panel display (FPD) manufacturing process if the ability of long stroke movement is proved. So a special Section Switching Algorithm (SSA) is derived from the resultant force and moment equations of the levitated tray which enables long stroke movement of the tray. In order to verify the feasibility of the suggested SSA, a simple test-setup of the EMS with 2 Section-changes is made up and servo-controlled in the simulation and experiment. The simulation shows the perfect changeover the EMs, and the experiment shows overall control performance of under ${\pm}40{\mu}m$ gap deviations. These results reveal that the newly suggested contactless linear bearing can simultaneously achieve high load capability and precision gap control as well as long stroke.