• Journal of Power Electronics
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• 제13권6호
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• pp.1051-1057
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• 2013

This paper proposes an implementable sun tracking algorithm for portable systems powered by alternative energy sources. The proposed system uses a 2-axis tilt sensor and a 3-axis magnetic sensor to measure the orientation and posture of the system, according to a horizon coordinates system, and compensate for tilt effects. Then, through an astronomical calculation, using the present time and position information obtained from GPS sensors, the azimuth and altitude of the sun in that location is calculated and converted to portable sun tracking system coordinates and used to control the A- and C-axes of the system.

• 한국정보기술학회 영문논문지
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• 제10권1호
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• pp.99-109
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• 2020

As environmental pollution has become severe due to the rapid increase in pollutant generation in the air, measurement, collection, and analysis of atmospheric environment information plays an important role. However, it is difficult to measure the high-resolution and real-time atmospheric environment of the cities and tourist spots with high population mobility only by measuring equipment of stationary measuring stations. Therefore, this paper proposes a portable atmospheric environment measurement system for real-time measurement and monitoring of atmospheric environment information. The proposed system is a portable client with a low-power wireless communication method. It is possible to reliably transmit and receive the measured data through a multi-threaded server to monitor the trend of pollutants in the air in real-time.

• 전자통신동향분석
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• 제35권2호
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• pp.69-78
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• 2020

Small portable devices such as mobile phones and laptops currently display a trend of high power consumption owing to their characteristics of high speed and multifunctionality. Low-power SoC design is one of the important factors that must be considered to increase portable time at limited battery capacities. Popular low power SoC design techniques include clock gating, multi-threshold voltage, power gating, and multi-voltage design. With a decreasing semiconductor process technology size, leakage power can surpass dynamic power in total power consumption; therefore, appropriate low-power SoC design techniques must be combined to reduce power consumption to meet the power specifications. This study examines several low-power SoC design trends that reduce semiconductor SoC dynamic and static power using EDA tools. Low-power SoC design technology can be a competitive advantage, especially in the IoT and AI edge environments, where power usage is typically limited.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.494-496
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• 2006

There are several types of communication method which is used for the supply of electric power stably. But the communication methods used in KEPCO have weak points in the viewpoint of economy, technology and management. The Satellite communication systems have competitive rover in price and technology for national wide utility owing to its wide area coverage and stability. For better practical use of satellite communication in power industry, we developed the portable satellite communication terminal. This paper presents various functions and composition of the portable terminal for rower industry.

• 한국기계가공학회지
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• 제21권9호
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• pp.71-77
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• 2022

In times of war or emergencies, weapon systems, such as radars, must receive stable power. This can be achieved using improved onboard portable power systems made of steel containers. However, a breakdown can occur in the event of random vibration during transportation via a vehicle or train. Electrical-power shortages or restrictions pose a significant threat to security. In this study, Composite Wheeled Vehicle(CWV) data and rail cargo data with Acceleration Spectral Density(ASD), specified in MIL-STD-810H METHOD 514.8, were interpreted as input data of the three-axis random vibration method using ANSYS 19.2. Modal analysis was performed up to 500 Hz, and deformations in modes 1 to 117 were calculated to utilize all ASD data. The maximum equivalent stress in the three-axis direction was obtained using a random vibration analysis. Similarly, the margin of safety was calculated using the derived equivalent stress and material properties. Overall, the analysis verified that the portable container designed for the power supply system satisfied the required vibration demands.

• 전기학회논문지
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• 제67권6호
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• pp.715-723
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• 2018

The energy storage system consists of batteries, power conditioning system and energy management system. If ESS is installed and operated in the field, SAT(Site Acceptance Test) of ESS is being essentially required for the safety and performance of ESS. Furthermore, in order to more accurately and reliably validate the performance of the ESS in advanced countries, it has been required to perform not only performance testing by H/W equipments but also performance verification by S/W tool. Therefore, this paper proposes the modeling of portable test equipment in order to evaluate the performance and reliability of ESS by using the PSCAD/EMTDC S/W. And also, the prototype of 30[kW] scaled portable test equipments is implemented based on the S/W modeling. From the results of various simulations and testings such as power quality, LVRT and anti-islanding tests, it is confirmed that 30[kW] scaled portable test equipment is useful for SAT of ESS, because the simulation results of PSCAD/EMTDC are identical to them of 30[kW] test equipment at the same test conditions.

• 한국콘텐츠학회논문지
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• 제7권11호
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• pp.102-110
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• 2007

본 논문에서는 UHF대역 중 900MHz 대역에서 동작하는 휴대용 RFID 리더를 설계하고 제작하여 그 제반 특성을 측정을 통하여 분석하였다. 측정 결과의 분석은 EPC Global에서 제안한 EPC Class 0 표준을 기준으로 수행되었다. 제안하는 RFID 리더는 약 11kbps의 속도로 태그와 데이터 통신을 수행하며, RF 최대 출력은 20dBm이다. 제안된 휴대용 RFID 리더는 초당 최대 68개의 태그를 인식할 수 있으며, 리더의 출력 전력이 20dBm인 경우 최대 인식 거리는 30cm 이다. 그리고 전체적인 크기는 $71mm{\times}55mm$로서 상용 제품과 비교했을 때 최대 90%, 최소 14% 감소된 것이다.

• 한국안전학회지
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• 제38권3호
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• pp.110-120
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• 2023

Following the Fukushima accident, portable equipment employed as accident mitigating systems have been installed and operated to reduce core damage and large early release frequencies. In addition, the establishment of an accident management strategy has gained importance. This study investigated the current status of portable equipment including the international portable equipment FLEX (diverse and flexible coping strategies), and domestic portable equipment multi-barrier accident coping strategy (MACST). Research on optimal utilization of MACST remains insufficient. As a preliminary study for establishing an optimal strategy, sensitivity studies were conducted to facilitate the priority of use on portable equipment, number of portable equipment, and dependency of operator actions based on a multi-unit probabilistic safety assessment model. The results revealed the conditions that reduced the multi-unit and site conditional core damage probabilities, indicating the optimal strategy of MACST. The results of this study can be used as a reference for establishing an optimal strategy that utilizes domestic safety equipment in the future.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.41-45
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• 2016

The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.

• 한국산학기술학회논문지
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• 제9권3호
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• pp.727-733
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• 2008

사용자가 안전한 WiBro 서비스를 받기 위해서 사용자 단말과 ACR(Access Control Router) 간에 인증이 선행되어야 한다. 그렇지 않을 경우, 많은 공격 위험으로부터 노출될 수 있다. 따라서 한국정보통신기술협회(TTA)에서는 휴대인터넷(와이브로) 서비스를 위한 상호 인증 절차 표준을 제정하였다. 이 표준 프로토콜은 PISIM(Portable Internet Subscriber Identity Module)을 이용하여 PE(Portable Equipment)와 ACR 간에 상호 인증을 수행한다. 그러나 표준은 인증에 필요한 메시지의 수가 대체적으로 많은 편이며 PISIM의 분실과 에러가 발생했을 경우에는 사용자는 무선인터넷 서비스를 사용할 수 없게 된다. 따라서 본 논문에서는 ACR과 PSS 간에 키 동의 프로토콜을 수행하여 PSS를 인증한다. 이때 PSS의 계산량을 지원하기 위한 PSD(Power Support Device)가 키 동의 프로토콜에 참여하게 된다. 이렇게 생성된 키는 ACR과 안전한 통신 세션을 맺고 있는 KAS(Key Authentication Server)에 PSS의 식별자와 키 정보를 암호화에서 저장한다. 끝으로 제안된 프로토콜의 안전성과 효율성을 분석한다.