• 전기전자학회논문지
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• 제23권4호
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• pp.1448-1456
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• 2019

본 연구에서는 작물재배용 단동식 유리온실 내에 LED 광원을 적용할 때, LED의 전원 공급을 위한 태양전지를 에너지 저감과 광투과율을 고려하여 Si 계열의 태양전지와 염료감응형 태양전지(DSSC)를 유리온실에 선별적 배치하고, 작물 재배에 유효한 태양전지의 광투과율을 결정하기 위해 유리온실의 천정과 측면에 대해 광투과율 변화에 따른 조도 시뮬레이션을 수행하였다. 또한, 유리온실에서 주광과 인공광인 LED 광원을 모두 고려하는 경우 최적 조명제어에 따른 유리온실의 에너지 절감 효과를 분석하였다.

• Journal of Communications and Networks
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• 제16권1호
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• pp.36-44
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• 2014

Exploiting the energy-delay tradeoff for energy saving is critical for developing green wireless communication systems. In this paper, we investigate the delay-constrained energy-efficient packet transmission. We aim to minimize the energy consumption of multiple randomly arrived packets in an additive white Gaussian noise channel subject to individual packet delay constraints, by taking into account the practical on-off circuit power consumption at the transmitter. First, we consider the offline case, by assuming that the full packet arrival information is known a priori at the transmitter, and formulate the energy minimization problem as a non-convex optimization problem. By exploiting the specific problem structure, we propose an efficient scheduling algorithm to obtain the globally optimal solution. It is shown that the optimal solution consists of two types of scheduling intervals, namely "selected-off" and "always-on" intervals, which correspond to bits-per-joule energy efficiency maximization and "lazy scheduling" rate allocation, respectively. Next, we consider the practical online case where only causal packet arrival information is available. Inspired by the optimal offline solution, we propose a new online scheme. It is shown by simulations that the proposed online scheme has a comparable performance with the optimal offline one and outperforms the design without considering on-off circuit power as well as the other heuristically designed online schemes.

• 농업과학연구
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• 제42권1호
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• pp.53-61
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• 2015

Development of highly efficient and energy-saving tractors has been one of the issues in agricultural machinery. For design of such tractors, measurement and analysis of load on major power transmission parts of the tractors are the most important pre-requisite tasks. Objective of this study was to perform pre-processing procedures before effective analysis of load data of agricultural tractors (30, 75, and 82 kW) during major field operations such as plow tillage, rotary tillage, baling, bale wrapping, and to select the suitable pre-processing method for the analysis. A load measurement systems, equipped in the tractors, were consisted of strain-gauge, encoder, hydraulic pressure, and radar speed sensors to measure torque and rotational speed levels of transmission input shaft, PTO shaft, and driving axle shafts, pressure of the hydraulic inlet line, and travel speed, respectively. The entire sensor data were collected at a 200-Hz rate. Plow tillage, rotary tillage, baling, wrapping, and loader operations were selected as major field operations of agricultural tractors. Same or different farm works and driving levels were set differently for each of the load measuring experiment. Before load data analysis, pre-processing procedures such as outlier removal, low-pass filtering, and data division were performed. Data beyond the scope of the measuring range of the sensors and the operating range of the power transmission parts were removed. Considering engine and PTO rotational speeds, frequency components greater than 90, 60, and 60 Hz cut off frequencies were low-pass filtered for plow tillage, rotary tillage, and baler operations, respectively. Measured load data were divided into five parts: driving, working, implement up, implement down, and turning. Results of the study would provide useful information for load characteristics of tractors on major field operations.

• 한국통신학회논문지
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• 제34권10A호
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• pp.760-768
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• 2009

본 논문에서는 선박에 적용할 e-네비게이션을 위한 HR(high rate)-WPAN(Wireless Personal Area Network) 시스템에 대한 전송 파라미터를 분석하여 최적 전송파라미터 선택방식을 제시한다. 본 논문에서는 IEEE 802.15.3 CSMA/CA기반의 HR-WPAN을 SAN(Ship Area Network)에 적용할 경우에 고려되어야하는 에너지 효율성 측면에서의 전송파라미터들을 분석하고 에너지를 절약할 수 있는 전송파라미터 결정방식에 대하여 각 선박환경별로 분석하여 제안한다. 특히 SAN환경에서 무선채널의 경로손실(path loss)을 결정하는 가장 큰 파라미터인 선박의 다양한 재질을 고려하여 각 HR-WPAN의 전송파라미터별로 에너지 소모량을 분석하여 파라미터 선택방안을 제시한다. 시뮬레이션 결과 선박환경에 따라서 전송률 선택방식, 전송전력 조절 방식 및 데이터 분할크기의 적절한 선택에 따라 에너지 효율성능이 결정됨을 보였다.

• 센서학회지
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• 제17권3호
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• pp.168-177
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• 2008

An indoor environmental monitoring system using IEEE 802.15.4 based wireless sensor network is proposed to monitor the amount of pollutant entering to the room from outside and also the amount of pollutant that is generated in indoor by the building materials itself or human activities. Small-size, low-power wireless sensor node and low power electrochemical sensor board is designed to measure the condition of indoor environment in buildings such as home, offices, commercial premises and schools. In this paper, two query models, the broadcasting query protocol and flooding query protocol, were designed and programmed as a query-based routing protocol in wireless sensor network for an environment monitoring system. The flooding query routing protocol in environment monitoring is very effective as a power saving routing protocol and reliable data transmission between sensor nodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.823-825
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• 2003

A sensor system was designed to measure real time vibro displacement of civil structure. The He-Ne laser is used for the displacement measuring method, because it guarantees short time stabilization, long time output power stability. Also, it guarantees simple maintenances and repairs under actual using condition. The line CCD image sensor(Tcd-142d) is used to detect the displacement of Ne-Ne laser responding to the vibro of civil structure. For accurate measurement and comparison, CDP-50 is used. Usually CDF-50 (Strain type displacement device) is used for the standard correction device of optical measurement equipments. The data processing part is consists of Optical sensor part, Wireless data transmission device, DAQp-1200, and LapView program. The displacement data of vibro from optical sensor part inputted to wireless data transmission device and then transmitted to DAQp-1200 in main control room. DAQp-1200 performs A/D conversion for the receiving data. After that the converted data inputted to computer system using LapView program for user display. The significance of this paper is to develope a convenient, accurate and lost saving real time displacement measurement system for the civil structure.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.517-520
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• 2005

무선 센서망은 망의 사용목적에 따라 빛, 온도, 진동, 자기 영역, 바람 등을 감지 할 수 있는 센서와 컴퓨팅 기술로 통합된다. 무선 노드들은 센서에서 감지된 정보를 처리하는 신호 처리 기술과 측정자에게 정보가 도달하게 하는 통신 제어 기술과, 무선으로 구동되고 배터리를 사용하기 때문에 발생하는 제한적 에너지 관리 기술이 구현된다. 그 중 신뢰성 있는 측정 및 감지를 하고자 한다면 망의 지속시간의 비중이 크기 때문에 효율적인 에너지 관리 기술이 필요하다. 따라서 본 논문에서는 하드웨어에서의 전원관리가 아닌 OSI 7계층 중 데이터 링크 계층에 해당하는 MAC(Medium Access Control)에서 기존의 무선 MAC 프로토콜인 CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance)과 무선 센서 MAC 프로토콜인 ER-MAC(Energy Rate Medium Access Control)에 대해 설명후 각각 프로토콜에 따른 망의 지속시간을 비교하여 효율성을 분석한다.

• 한국자동차공학회논문집
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• 제1권3호
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• pp.109-117
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• 1993

A carbon/epoxy composite drive shaft used for the power transmission of the automobiles with steel joints. Compared with the metallic drive shaft, the composite one has the weight saving of 50% with equivalent torsional strength and fatigue characteristics. In this study, the filament winding technique for the composite tube and composite/metal joining technique are estabilished. The performance test of the drive shaft is carried out. The optimal condition of the surface roughness of the steel adherend was $1.5{{\mu}m}$ to $2.5{{\mu}m}$, and the optimal condition of the bonding thickness was 0.15mm. Maximum torque and torsional stiffness of the composite drive shaft manufactured by filament winding process were found to be $210kg{\cdot}m$ and $18.5kg{\cdot}m/deg$, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.523-526
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• 1987

The present metering transformer being used for measurement has the characteristics of high reliability and high efficiency. In the future, however, it is thought that the scales of mettering transformer will be larger and the cost of production will increase as the transmission voltage ascends to UHV. And, also, it wilt be not easy to ensure the aseismatic capability. For the purpose of settling these problems, by applying optical sensor technology to electric power systems and by developing optical current transformer and potential transformer, we will realize the saving in energy, reduction of cost prise, improvement in measuring precision.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 가을 학술발표논문집 Vol.31 No.2 (3)
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• pp.124-126
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• 2004

본 논문은 CAM(Constant Awake Mode), 및 PSM(Power Saving Mode)을 지원하는 IEEE 802.l1b[1] Infrastructure 환경에서 전송 프로토콜이 이동기기의 WNIC(Wireless Network Interface Card) 에너지 소비에 미치는 영향을 분석하고 단위 시간 동안 전송되는 데이터 양에 기반한 IEEE 802.l1b WNIC 에너지 모델을 제안한다. 제안하는 에너지 모델은 IEEE 802.l1b 환경에서 CAM 및 PSM 모드를 사용할때, 실제 측정한 값을 기반으로 설계되었다. 제안된 에너지 모델은 실험을 통하여 정확성을 검증하고, IEEE 802.l1b를 기반으로한 저전력 통신 관련 연구에서 시뮬레이션 시 사용 가능한 에너지 모델임을 밝힌다.