• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.33-40
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• 2017

In this paper, we propose a sink-location management and data-routing scheme to effectively support the mobile sink in solar-powered WSN. Battery-based wireless sensor networks (WSNs) have a limited lifetime due to their limited energy, but solar energy-based WSNs can be supplied with energy periodically and can operate forever. On the other hand, introduction of mobile sink in WSNs can solve some energy unbalance problem between sink-neighboring nodes and outer nodes which is one of the major challenges in WSNs. However, there is a problem that additional energy should be consumed to notify each sensor node of the location of the randomly moving mobile sink. In the proposed scheme, one of the nodes that harvests enough energy in each cluster are selected as the cluster head, and the location information of the mobile sink is shared only among the cluster heads, thereby reducing the location management overhead. In addition, the overhead for setting the routing path can be removed by transferring data in the opposite direction to the path where the sink-position information is transferred among the heads. Lastly, the access node is introduced to transmit data to the sink more reliably when the sink moves frequently.

• Membrane and Water Treatment
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• 제2권4호
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• pp.239-250
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• 2011

A photovoltaic powered ultrafiltration and reverse osmosis system was tested with a number of natural groundwaters in Australia. The objective of this study was to compare system performance at six remote field locations by assessing the impact of water composition and fluctuating energy on inorganic contaminant removal using a BW30-4040 membrane. Solar irradiance directly affected pressure and flow. Groundwater characteristics (including TDS, salts, heavy metals, and pH), impacted other performance parameters such as retention, specific energy consumption and flux. During continual system operation, retention of ions such as $Ca^{2+}$ and $Mg^{2+}$ was high (> 95%) with each groundwater which can be attributed to steric exclusion. The retention of smaller ions such as $NO_3{^-}$ was affected by weather conditions and groundwater composition, as convection/diffusion dominate retention. When solar irradiance was insufficient or fluctuations too great for system operation, performance deteriorated and retention dropped significantly (< 30% at Ti Tree). Groundwater pH affected flux and retention of smaller ions ($NO_3{^-}$ and $F^-$) because charge repulsion increases with pH. The results highlight variations in system performance (ion retention, flux, specific energy consumption) with real solar irradiance, groundwater composition, and pH conditions.

• 한국항공운항학회지
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• 제23권3호
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• pp.1-7
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• 2015

In the present study, we conducted the research on the high efficiency propulsion system for the development of long-endurance UAV with an electric propulsion system. For the long endurance UAV, fair aerodynamic characteristics with the high efficiency of the propulsion system is required because the flight power and the duration time of the long-endurance UAV vary greatly depending on the efficiency of the propulsion system. Therefore, in this study, the tracking program which records the performance of motor, propeller was developed because of their wide variation in the efficiency depending on the using condition, and records from the existing flight test program were utilized to check the accuracy of the program we had developed. For the development of future long-endurance solar UAV, we confirmed the applied voltage of motor, the optimal rotation of propeller and the gear ratio of reduction gear in order to get the highest efficiency on the propulsion system at the optimal flying condition.

• 전기전자학회논문지
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• 제26권3호
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• pp.483-487
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• 2022

본 논문에서는 태양에너지 하베스팅을 위한 자가발전 아두이노 시스템을 설계하고 이의 동작을 설명한다. 이를 위해서 아두이노 시스템이 시시각각 변하는 태양에너지의 양을 센싱하고 이에 따라서 active mode와 sleep mode의 동작 시간의 비율을 스스로 조정해서 주어진 태양 빛의 세기에 대해서 최적으로 동작할 수 있는 동작 조건을 스스로 찾아가는 방법을 설명하고 이의 동작을 검증한다. 본 논문에서 개발한 active mode와 sleep mode의 동작 시간의 비율의 자가 조절을 통해서 태양 빛의 세기가 충분히 강할 경우에는 아두이노 시스템이 active mode로 지속적으로 구동되고, 태양광으로부터 전력을 충분히 공급받을 수 없는 경우 sleep mode를 사용하여 전력 소모를 최소화한다. 그 결과 active mode를 지속적으로 구동하는 것에 비해 sleep mode를 사용하는 경우 전력 소모를 최대 81.7% 줄여 에너지 소비를 최소화할 수 있다는 것을 알 수 있다. 또한 빛의 세기가 중간 수준일 때에는 active mode와 sleep mode의 비율을 빛의 세기에 맞게 적정하게 배분하여 동작하게 한다. 본 논문에서 제안한, 스스로 active mode와 sleep mode의 동작 시간 비율을 조절하는 방법은 특히 높은 전력 소비 효율 특성이 필요한 웨어러블 및 바이오-헬스용 자가발전 시스템을 에너지 효율적으로 동작시킬 때에 도움이 될 것으로 생각된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.594-597
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• 2014

본 논문에서는 국제 태양광 자동차 대회를 참가하는 태양광 자동차 프론트 너클의 경량화 설계에 관한 연구를 진행한다. 이를 위해 Cattle grid 를 포함한 실제 주행환경과 태양광 자동차를 동역학 시뮬레이션 모델로 구성하고 대회에서 차량의 평균속도인 70Km/h 로 주행 시, 서스펜션에서 발생되는 동하중을 측정하였다. 프론트 너클을 유한요소로 구성하고 다물체 동역학 시뮬레이션에서 도출된 하중들로 위상최적기법을 통해 프론트 너클의 경량화를 이루었다. 마지막으로 피로해석을 수행하여 그 타당성을 검증하였다.

• 전자통신동향분석
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• 제34권5호
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• pp.36-47
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• 2019

Smart window technology has become a major component of smart buildings, leading to energy savings and enhanced functionality. Smart windows work like curtains or blind screens, blocking external light sources. Smart window components employ electrochromic or photochromic materials that can selectively block sunlight when electricity is applied. The installation of low-E glass and building-integrated photovoltaics (BIPV) is being encouraged in accordance with the policy on saving building energy. To incorporate BIPV into smart windows, the transparency and colors of transparent photovoltaics must be optimized. The power sources required to operate these smart windows take advantage of the transparent color of the solar cells, which also facilitates aesthetics. Self-powered smart windows that combine electrochromic or photochromic screens with transparent solar cells suggest a promising convergent technology.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1045-1047
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• 1992

Photovoltaics is considered to be one of the most promising technologies which can greatly contribute to future energy supply because of a large, secure, essentially inexhaustible and broadly available resource - sunlight. However, recent progresses in photovoltaics make also possible its short-term practical application in some areas. Among them the solar air conditionner powered by photovoltaic system attracts considerable interest due to its main advantage which consists in the reduction of drastically increasing electricity peak load in summer season. In this review paper our current study on the solar air conditionner will be briefly summarized.

• 항공우주시스템공학회지
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• 제10권4호
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• pp.50-58
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• 2016

선행 연구 개발을 통하여 장기 체공 태양광 무인기 복합재 날개의 경량화는 매우 중요한 요소임을 확인하였다. 날개 외피의 좌굴 방지와 비틀림 방지 역할을 하는 구조물인 리브는 날개의 구성 요소 중에 필수적이다. 본 연구는 최적의 복합재 리브를 설계, 제작하기 위하여 복합소재의 이방성 특성을 고려한 다양한 적층 패턴 적용 및 형상에 대하여 리브를 제작하였고. MSC. Patran/Nastran을 이용한 유한요소 해석을 통하여 최대 하중 및 변위 형상을 확인하였으며, 구조 시험을 통하여 측정된 시험 결과를 바탕으로 최적의 리브를 제시하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.531-534
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• 2010

본 논문에서는 공유형 태양 에너지 기반 센서 시스템을 위한 가상 에너지 시스템의 개념을 이용한 효율적인 에너지 관리 기법을 소개한다. 가상 에너지 시스템은 한 센서 노드에서 동시에 수행되는 여러 응용들이 각각 자신이 사용할 에너지양을 예약하여 사용할 수 있게 하는 추상화 계층이다. 이렇게 함으로서 응용과 시스템의 수정 없이, 수집되는 태양 에너지를 각 응용에서 조화롭게 사용할 수 있고, 따라서 태양 에너지의 효율적 사용이 가능하게 된다. 실험 결과는 가상 에너지 시스템이 효율적이고 안정적으로 동작하여, 한 센서 노드에서 여러 응용이 조화롭게 실행됨을 보여주고 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1361-1364
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• 1990

In order to tackle global environmental problems such as destruction of the ozone layer or climatic changes due to atmospheric temperature increase, the acquisition of plentiful and precise data is necessary. Therefore, a means of conducting long-lasting high-resolution measurements over broad areas is required. A feasibility study has been made on a high altitude (20km), super-pressured helium-filled PLTA (Powered Ligher-than-Air) vehicle as an ideal platform for environmental observation. It has a long service life and carries a larger payload than an artificial satellite. This PLTA platform uses an electric propulsion system to maintain position in space against wind currents. The thruster is driven by solar power acquired from solar cells. For night use, solar energy is stored in regenerative fuel cells. This study focuses on energy balance and structural analysis of the hull and platform. The platform is capable of conducting high resolution remote sensing as well as having the capability to serve as a telecommunications relay. The platform could replace a number of ground-based telecommunications relay facilities, guaranteeing sufficient radio frequency intensity to secure good quality telecommunication transmittal. The altitude at which the platform resides has the lowest wind flow in the lower stratosphere, and permits viewing from the ground within a 1,000km range. Because this altitude is much lower than that required of an artificial satellite, the measuring resolution is a couple of thousand times higher than with artificial satellites. The platform can also be used to chase typhoons and observe them from their sources in tropical regions.