• 태양에너지
• /
• 제19권2호
• /
• pp.21-28
• /
• 1999

This study was carried out to investigate the effect of energy transport using capillary pumped loop with PVA sponge wick. The results obtained from this study are as follows. The configuration of capillary pumped loop was adequate and PVA sponge was of great use for the manufacture of capillary pump. The energy transport reached maximum when the working fluid amount was 750cc the wall temperature distribution indicated high values through out the entire length of the pipe. As the opening of a nozzle was increased, energy transport was increased but the effect was decreased.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 D
• /
• pp.2956-2958
• /
• 2000

This paper describes the design of a real time traffic data acquisition system using loop detector and piezzo sensor. Loop detector is the cheapest method to measure the speed and piezzo is used to detect the vehicle axle information. A ISA slot based I/O board is designed for data acquisition and PC process the raw traffic data and transfer the data to the host system. Simulation kit is designed with toy car kits. simulated loop detector and piezzo sensor. The data acquisition system collects up to 10 lane highway traffic data such as vehicle count. speed. length axle count. distance between the axles. The data is processed to generate traffic count, vehicle classification, which are to be used for ITS. The system architecture and simulation data is included and the system will be tested for field operation.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 동계학술발표대회 논문집
• /
• pp.33-38
• /
• 2008

A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The Size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

• 대한기계학회논문집B
• /
• 제24권3호
• /
• pp.346-353
• /
• 2000

In this paper, heat transfer characteristics of a loop type capillary heat pipe were experimentally investigated for the effect of several fill charge ratios of working fluid and heat loads. This type of heat pipe consists of a heating section, a cooling section and an adiabatic section. The heat pipe used has a 0.002m internal diameter, a 0.34m length in one turn and consists of 19 turns. Heating and cooling sections each have a length of 70mm. Experiments were performed to measure the temperature distributions and the pressure variation of the heat pipe. Heat transfer performance, effective thermal conductivity, boiling heat transfer and condensation heat transfer coefficients were calculated for various operating conditions of heat pipe and it was found that heat transfer characteristics of this type heat pipe were very excellent. As shown by this experimental study, this type of heat pipe operates by oscillatory flow caused by pressure and temperature oscillations.

• Fibers and Polymers
• /
• 제5권4호
• /
• pp.275-279
• /
• 2004

Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed rig, which can rotate a yam at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yam rotating speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions, a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns.

• 조명전기설비학회논문지
• /
• 제16권6호
• /
• pp.102-108
• /
• 2002

본 논문에서는 지능형 교통 시스템(ITS)의 기본 정보인 차량정보와 도로정보를 실시간으로 제공하기 위하여 루프 검지기와, 피에조 센서를 사용한 차량정보 수집 시스템의 설계를 다루었다. 루프검지기와 피에조 센서를 도로차선마다 설치하고 프로세서와 입/출력 보드를 통하여 샘플링 주기에 의하여 센서의 신호를 읽어들여 차량 및 교통정보를 생성한다. 생성된 정보는 패킷형태로 만들어져 RS232C 직렬 통신과 모뎀을 통하여 원격에 있는 교통 관제시스템으로 전송된다. 이를 위하여 EISA BUS규격의 32채널 입/출력 보드와 차량정보 수집 프로그램을 설계하고 시뮬레이션 시스템에서 확인하였다.

• Transactions on Control, Automation and Systems Engineering
• /
• 제3권4호
• /
• pp.242-249
• /
• 2001

In this paper, the open-loop state response of the two-time-scale systems by unified approach using the $\delta$-operator is presented with an example of the aircraft longitudinal dynamics. First, the $\delta$-operator system unifies both the continuous system and the discrete system simultaneously, and the $\delta$-operator approach improves the finite word-length characteristics. This saves more computing time than that of the discrete system. Second, the singular perturbation method by block diagonalization reduces the sizes and orders of the systems. This also reduces the floating-point operations (flops). The advantage of those two approaches is shown by comparing our results with the earlier ones in the illustrative example of the longitudinal motion of F-8 aircraft.

• ETRI Journal
• /
• 제28권4호
• /
• pp.506-508
• /
• 2006

A frequency selective surface (FSS), whose unit cell consists of a ternary tree loop loaded with a modified tripole, is proposed to block multiple frequency bands. Target frequency bands correspond to Korean personal communication services, cellular mobile communication, and 2.4 GHz industrial, scientific, and medical bands. Through the adjustment of inter-element and inter-unit cell gaps, and adjustment of the length of elements, we present an FSS design method that makes the precise tuning of multiple resonance frequencies possible. Additionally, to verify the validity of our approach, simulation results obtained from a commercial software tool and experimental data are also presented.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
• /
• pp.117-120
• /
• 2002

In this paper, we construct cryptographic accelerators using hardware Implementations of HMACS based on a hash algorithm such as MD5.It is basically a secure version of his previous algorithm, MD4 which is a little faster than MD5 The algorithm takes as Input a message of arbitrary length and produces as output a 128-blt message digest The input is processed In 512-bit blocks In this paper, new architectures, Iterative and full loop, of MD5 have been implemented using Field Programmable Gate Arrays(FPGAS). For the full-loop design, the performance Is about 500Mbps @ 100MHz

• 한국ITS학회:학술대회논문집
• /
• 한국ITS학회 2004년도 제3회 정기총회 및 추계학술대회
• /
• pp.186-191
• /
• 2004