• 전기학회논문지
• /
• 제66권3호
• /
• pp.568-574
• /
• 2017

This paper proposes a demagnetization fault diagnosis method for interior permanent magnet synchronous motors(IPMSMs). In particular, a demagnetization fault is one of the most frequent electrical faults in IPMSMs. This paper proposes an estimation method for permanent magnet flux. The method is based on linear interpolation. The effectiveness of the proposed method for diagnose demagnetization faults is verified through various operating conditions by finite element simulation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.309-310
• /
• 2005

Generally, the dielectric constant and loss tangent are gotten by resonators. This paper presents analysis of the comparing the dielectric constant and loss tangent from the Ring, T and series gap structures. The T structure can be analyzed easily at wideband characteristic with simple design. the Ring can ignore the radiation loss from the open-ended effect. the Series gap can get more accurate permittivity than a Ring structure. The Used materials were dupont9599 LTCC ceramic and daeju0086 Ag.

• Journal of Power Electronics
• /
• 제13권5호
• /
• pp.746-756
• /
• 2013

The modularized subunit of an electronic power transformer (EPT) is a series connection of two H-bridge voltage-source converters and a DC-DC converter with a high-frequency isolation transformer (HFIT). On the basis of cascading and paralleling the modularized subunits, EPT can be used in high-voltage and large-current applications in the power system. This paper discusses the steady state analysis of the modularized subunit of EPT. Theoretical analysis considers the influences of the two H-bridge voltage-source converters on the two sides of the DC-DC converter. We deduce the formulas of the theoretical calculation on the internal electrical characteristics of EPT (e.g., the voltages of the DC-bus capacitor and the primary side peak current of the HFIT). This paper provides guidance on the design and selection of EPT key elements (e.g., the DC-bus capacitors and HFIT). Experimental results are obtained from a single subunit of a laboratory model rated at 962 V, 15 kVA. All calculations, simulations, and experiments confirm the theoretical analysis of the subunit of EPT.

• Advances in nano research
• /
• 제12권2호
• /
• pp.151-165
• /
• 2022

Micro-scale serpentine structure fibers are widely used as flexible sensor in the manufacturing of micro-nano flexible electronic devices because of their outstanding non-linear mechanical properties and organizational flexibility. The use of melt electrowriting (MEW) technology, combined with the axial bending effect of the Taylor cone jet in the process, can achieve the micro-scale serpentine structure fibers. Due to the interference of the process parameters, it is still challenging to achieve the precise deposition of micro-scale and high-consistency serpentine structure fibers. In this paper, the micro-scale serpentine structure fiber is produced by MEW combined with axial bending effect. Based on the controlled deposition of MEW, applied voltage, collector speed, nozzle height and nozzle diameter are adjusted to achieve the precise deposition of micro-scale serpentine structure fibers with different morphologies in a single motion dimension. Finally, the influence mechanism of the above four parameters on the precise deposition of micro-scale serpentine fibers is explored.

• 한국IT서비스학회지
• /
• 제19권3호
• /
• pp.101-115
• /
• 2020

Electronic voting is one of information technology service to handle a wide range of functions, including registration, certification, input and results of voting, using electronic technology, depending on the degree of automation. It helps voters exercise their voting rights not only for individual suffrage but also for major corporate decisions as shareholders by expressing their opinions regardless of geographical and time constraints. Such electronic voting helps open and expand voting participation, but on the contrary, it is possible to identify who voted and what kind of vote, such voting cannot guarantee confidentiality. Therefore, if blockchain technology is applied to electronic voting, it can increase the speed of processing and confidentiality by encrypting voting information. In this regard, the study aims to identify institutional issues on how electronic voting can be activated at a company's shareholders' meeting, and to find ways to overcome the limitations of existing electronic voting by utilizing the technical characteristics of blockchain. This study proposes a consortium-type blockchain-based electronic voting system to enhance the convenience and reliability of electronic voting for shareholders' meetings. In addition, this paper suggests how to enhance shareholders' profits through electronic voting at shareholders' meetings, as well as its policy measures and future improvements.

• International Journal of Computer Science & Network Security
• /
• 제21권4호
• /
• pp.249-254
• /
• 2021

Our society is depending on mobile devices that play a major role in our lives. Utilizing these devices is possible due to their speed power and efficiency in performing basic as well as sophisticated operations that can be found in traditional computers like desktop workstations. The challenge with using mobile devices is that organizations are concerned with the interference between personal and corporate use due to Bring Your Own Device (BYOD) trend. This paper highlights the importance of mobile devices in our daily tasks and the associated risks involved with using these devices. Several technologies and countermeasures are reviewed in this paper to secure the mobile devices from different attempts of attacks. It is important to mention that this paper focuses on technical measures rather than considering different aspects of security measures as recommended by the cybersecurity community.

• 정보학연구
• /
• 제3권1호
• /
• pp.89-97
• /
• 2000

통신상의 전자상거래를 위해서는 전자화폐 시스템이라 불리는 새로운 개념의 지불 시스템이 필요하다. 전자화폐는 기존의 화폐를 디지털화한 정보이다. 그러나 전자화폐의 안전성은 기존의 화폐와는 달리 어떤 물리적 조건에 의존하지 않기 때문에 위조와 변조가 쉽게 이루어질 수 있으며, 쉽게 추적 당할 수 있다. 전자화폐가 안심하고 새로운 지불 수단으로 사용되기 위해서는 안전성과 사용자의 프라이버시가 보장되어야 한다. 본 논문에서는 기존에 제안되어진 전자동전 시스템, 분할 가능한 전자화폐, 전자면허등의 전자화폐시스템을 분석하고 통신량과 계산량에서 효율적이며, 전자면허의 문제점을 해결할 수 있는 시스템을 제안한다.

• Transactions on Electrical and Electronic Materials
• /
• 제15권1호
• /
• pp.1-6
• /
• 2014

Self-exciting electronic ballast, of small size, and low cost, and high power, with no stroboscopic effect, no noise, is widely used in the general lighting market. This paper describes the cause of high switching loss of self-exciting electronic ballast, based on its operational principle; then, to reduce the switch temperature and increase the reliability of the product, the drive circuit has been improved, to achieve soft-switching. The theory analysis, simulation and experimental result prove the feasibility and compatibility of this new method in practice. Finally, the design procedure and winding method of the self-exciting current transformer are introduced.

• 한국산업융합학회 논문집
• /
• 제27권1호
• /
• pp.17-24
• /
• 2024

Recently, retail technology has been developed by the rapid evolution of e-commerce and a representative example is ESL technology. In this study, we investigate ESL technology, market status and forecasts, and analyze the competitive structure between relational companies. Market analysis refers to data from market reports of Marketsandmarkets and Research, and internet media. In ESL, the display field is predicted to account for 43% of the total market in 2026, and is converting from LCD to electronic paper. The segmented type is becoming more advanced into the full-graphic type, and CAGR of 18.7% for 3-7 inches and 20.6% for 7-10 inches is predicted. The demand for ESL is greatest in North America and Europe, but CAGR is the highest in the Asia-Pacific region at 19.1%. Since ESL technology has a lot of overlap with semiconductor and display technology, the Asia-Pacific region is relatively advantageous, and this has led to rapid growth of domestic companies. However, it is expected that competition from European companies that are actually owned by Chinese companies will increase in the future, so continuous technological development and new market development are necessary.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권5호
• /
• pp.2357-2380
• /
• 2019

In this paper, we investigate the impact of hardware impairments (HWIs) on the performance of a downlink massive MIMO system. We consider a single-cell system with maximum ratio transmission (MRT) as precoding scheme, and with all the HWIs characteristics such as phase noise, distortion noise, and amplified thermal noise. Based on the system model, we derive closed-form expressions for a typical user data rate under two scenarios: when a common local oscillator (CLO) is used at the base station and when separated oscillators (SLOs) are used. We also derive closed-form expressions for the downlink transmit power required for some desired per-user data rate under each scenario. Compared to the conventional system with ideal transceiver hardware, our results show that impairments of hardware make a finite upper limit on the user's downlink channel capacity; and as the number of base station antennas grows large, it is only the hardware impairments at the users that mainly limit the capacity. Our results also show that SLOs configuration provides higher data rate than CLO at the price of higher power consumption. An approach to minimize the effect of the hardware impairments on the system performance is also proposed in the paper. In our approach, we show that by reducing the cell size, the effect of accumulated phase noise during channel estimation time is minimized and hence the user capacity is increased, and the downlink transmit power is decreased.