• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2006년도 추계학술대회
• /
• pp.9-14
• /
• 2006

Open loop or ground water heat pump systems are the oldest of ground-source systems. Standing column wells can be used as highly efficient ground heat exchanger in geo-thermal heat pump systems, where hydrological and geological conditions are suitable. These systems require some careful considerations for well design, ground water flow, heat exchanger selection etc This paper describes 9round water temperature variations, performances in heat ins and cool ing mode and the results of ground water analysis.

• 한국분무공학회지
• /
• 제8권2호
• /
• pp.24-30
• /
• 2003

An experimental study was performed to investigate the influence factors of drop formation in electrohydrodynamic atomization. The mode of electrohydrodynamic atomization depended on the various factors such as the flow rate of the liquid, the inner diameter of the nozzle, the distance between the nozzle tip and the ground electrode, the shape of the ground electrode. and the applied high voltage. This work was performed to investigate the experimental analysis for the flow pattern visualization of droplets, and the relationship between voltage application and the behavior of liquid atomization. Uniform drops of different sizes can be obtained at the inception of the spindle mode by charging the flow rate and the electric field. The drop size also decreased when the flow rate was raised for the spindle mode. The whipping motion occurred beyond 7kV and before the corona started to take effect.

• 한국항행학회논문지
• /
• 제28권2호
• /
• pp.246-249
• /
• 2024

In this paper, we present a miniaturized differential line (DL) using inductance-enhanced corrugated ground planes (LCGP) for effective common-mode (CM) noise suppression in high-speed packages and printed circuit boards. The LCGP-DL demonstrates the CM noise suppression in the frequency range from 2.09 GHz to 3.6 GHz. Furthermore, to achieve the same low cutoff frequency, the LCGP-DL accomplishes a remarkable 23.2% reduction in size compared to a reference DL.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1876-1879
• /
• 2003

Due to the conventional half-bridge switch-mode converters for dc motor drive have been usually using unbalanced circuit topologies which generate common-mode currents through parasitic capacitors distributed between the ground and the dc motor frame such as the heat-sink of switching devices or the frame of the dc motor. This paper describes methods that cancel common-mode current generated in half-bridge switch-mode converters by using circuit balancing technique. The circuit balancing is to make the noise pickup or occurring in both conductor lines, signal and return pathes, is equal in amplitude and opposite in phase so that it will be canceled out in the ground plane. The common-mode current cancellation in the proposed converter is confirmed by experimental results.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1881-1884
• /
• 2003

In some requirements of dc motor drive circuit applications are high quality output with generation of low internal conducted EMI. However the conventional dc motor drive circuits have been usually using unbalanced circuit which generates the high conducted EMI to the frame ground. This paper presents a balanced dc motor drive circuit which is effective way to reduce the common-mode noise. The circuit balancing is to make the noise pick up or occurring in both conductor lines, signal path and return path is equal in amplitude and opposite phase so that it will cancel out in the frame ground. The common-mode conducted noise reduction of this proposed dc motor drive is confirmed by experimental results.

• ETRI Journal
• /
• 제33권6호
• /
• pp.953-956
• /
• 2011

A novel dual-mode bandpass filter (BPF) using a dual spiral-shaped defected ground waveguide (DGW) resonator is proposed in this letter. The dual-mode characteristic of this filter is achieved by loading a defected T-shaped stub at the midline of the spiral-shaped DGW resonator. Also, non-orthogonal input and output feed-lines are adopted in the filter. Based on the compact DGW structure, a dual-mode BPF with central frequency of 1.5 GHz for the global positioning system is designed, fabricated, and measured. Measured results agree well with the predicted response and verify the proposed methodology.

• 한국측량학회지
• /
• 제9권2호
• /
• pp.103-113
• /
• 1991

SPOT 수치영상자료를 이용한 지상좌표 계산 과정에서 지상기준점 및 검사점 입럭좌표의 정확도는 계산 결과의 신빙성에 커다란 영향을 준다. CRT 모니터상에 직접 나타난 SPOT 원초 영상은 일반적으로 지상물체의 판별과 점위치 결정에 적합하지 않으므로 전체영상의 대비개선, 영상소보간, 경계선강조, 공간필터처리 등 적절한 영상처리 기병의 적용이 필요하다. 본 연구에서는 대상지역의 3차원 위치 결정과 파장대특성분석에 이용되는 SPOT 위성영상의 시각분석에 필요한 수치영상처리기법의 원리를 고찰하고, 그 적용을 위한 알고리즘을 개발하여 프로그래밍 하였으며, 실제 P-mode 및 XS-mode의 SPOT 영상을 이용하여 고해상도 천연색영상인 SPOT P＋XS 영상으로 합성하였다.

• 한국안전학회지
• /
• 제33권1호
• /
• pp.81-87
• /
• 2018

The seismic response, the natural frequencies and the mode shapes of an offshore wind turbine with twisted tripod substructure subject to various pile-ground interactions are discussed in this paper. The acceleration responses of the tower head by four historical earthquakes are presented as the seismic response, while the other loads are assumed as ambient loads. For the pile-ground interactions, the fixed, linear and nonlinear models are employed to simulate the interactions and the p-y, t-z and Q-z curves are utilized for the linear and nonlinear models. The curves are designed for stiff, medium and soft clays, and thus, the seven types of the pile-ground interactions are used to compare the seismic response, the acceleration of the tower head. The mode shapes are similar to each other for all types of pile-ground interactions. The natural frequencies, however, are almost same for the three clay types of the linear model, while the natural frequency of the fixed support model is quite different from that of the linear interaction model. The wind turbine with the fixed support model has the biggest magnitude of acceleration. In addition, the nonlinear model is more sensitive to the stiffness of clay than the linear pile-ground interaction model.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 동계학술발표대회 논문집
• /
• pp.21-26
• /
• 2008

Recently, small and medium-sized buildings have employed a multi-heat pump. The major benefits of the multi-heat pump over a conventional system are that it is easier system to maintain along with a diversification of facility use, and high comfortability. The performance of multi-heat pump systems can be enhanced by using geothermal energy instead of air source energy. This paper describes the multi-heat pumps applied in an ground source heat pump system for an actual building. The performance of a ground source multi-heat pump installed in the field was investigated in cooling mode. The maximum COP of the systems with single U-tube and double tube ground loop heat exchangers were 6.6 and 6.0, respectively. It is suggested that the new algorithms to control the flow rate of secondary fluid for ground loop heat exchanger have to be developed in order to enhance the performance of the system.

• 대한원격탐사학회지
• /
• 제26권3호
• /
• pp.335-346
• /
• 2010

Recently, ESA (European Space Agency) has launched CryoSAT-2 for polar ice observations. CryoSAT-2 is equipped with a SIRAL (SAR/interferometric radar altimeter), which is a high spatial resolution radar altimeter. Conventional altimeters cannot measure a precise three-dimensional ground position because of the large footprint diameter, while SIRAL altimeter system accomplishes a precise three-dimensional ground positioning by means of interferometric synthetic aperture radar technique. In this study, we developed an efficient SIRAL SARIn mode processing technique to measure a precise three-dimensional ground position. We first simulated SIRAL SARIn RAW data for the ideal target by assuming the flat Earth and linear flight track, and second accessed the precision of three-dimensional geopositioning achieved by the proposed algorithm. The proposed algorithm consists of 1) azimuth processing that determines the squint angle from Doppler centroid, and 2) range processing that estimates the look angle from interferometric phase. In the ideal case, the precisions of look and squint angles achieved by the proposed algorithm were about -2.0 ${\mu}deg$ and 98.0 ${\mu}deg$, respectively, and the three-dimensional geopositioning accuracy was about 1.23 m, -0.02 m, and -0.30 m in X, Y and Z directions, respectively. This means that the SIRAL SARIn mode processing technique enables to measure the three-dimensional ground position with the precision of several meters.