• Title/Summary/Keyword: velocity information

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Three-dimensional Guidance Law for Formation Flight of UAV

  • Min, Byoung-Mun;Tahk, Min-Jea
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.463-467
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    • 2005
  • In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.

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Correlation Analysis between Meteorological Factors and Crop Products (농산물 생산량과 기상요소의 상관관계 분석)

  • Lee, Ki-Kwang;Ko, Kwang-Kun;Lee, Joong-Woo
    • Journal of Environmental Science International
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    • v.21 no.4
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    • pp.461-470
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    • 2012
  • Agriculture is more influenced by environmental factors rather than other industries. Among the environmental factors, the meteorological conditions mainly impact the output of agricultural products. Hence, the purpose of this study is to analyze the impact of meteorological factors on the output of elemental agricultural products. As a first step, we obtained the data of the meteorological factors (i.e., precipitation, humidity, temperature, insolation, snowdrifts, wind velocity) and the output of the various agricultural products (i.e., grain, fruits and vegetables, root crops, green vegetables, seasoned vegetables, fruits, special crops) from the year 1990 to 2009 (20 years) of Seoul and the six metropolitan cities in Korea. Then, the analysis of the correlation between the agricultural product with the largest output and the meteorological factors of the place where the corresponding agricultural product is most produced, was carried out in order to determine the core meteorological factor that most impacts the output of agricultural product. The correlation analysis revealed that humidity, insolation and wind velocity have been the crucial meteorological factors to influence the output of the agricultural products. From the result, we can induce that the meteorological forecast information about the vital meteorological factors, i.e., humidity, insolation and wind velocity, facilitates the optimized cultivation plan to maximize the output of agricultural products.

Design and Fabrication of Silicon Flow Sensor For Detecting Air Flow (유속 감지를 위한 실리콘 유량센서의 설계 및 제작)

  • 이영주;전국진;부종욱;김성태
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.5
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    • pp.113-120
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    • 1994
  • Silicon flow sensor that can detect the velocity and direction of air flow was designed and fabricated by integrated circuit process and bulk micromachining technique. The flow sensor consists of three-layered dielectric diaphragm, a heater at the center of the diaphragm, and four thermopiles surrounding the heater at each side of diaphragm as sensing elements. This diaphragm structure contributes to improve the sensitivity of the sensor due to excellent thermal isolation property of dielectric materials and their tiny thickness. The flow sensor has good axial symmetry to sense 2-D air flow with the optimized sensing position in the proposed structure. The sensor is fabricated using CMOS compatible process followed by the anisotropic etching of silicon in KOH and EDP solutions to form I$\mu$ m thick dielectric diaphragm as the last step. TCR(Temperature Coefficient of Resistance) of the heater of the fabricated sensors was measured to calculate the operating temperature of the heater and the output voltage of the sensor with respect to flow velocity was also measured. The TCR of the polysilicon heater resistor is 697ppm/K, and the operating temperature of the heater is 331$^{\circ}C$ when the applied voltage is 5V. Measured sensitivity of the sensor is 18.7mV/(m/s)$^{1/2}$ for the flow velocity of smaller than 10m/s.

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A Study on Flow Characteristics in a PCV valve according to Various Differential Pressures (차압에 따른 PCV 밸브 유동 특성에 관한 연구)

  • Lee, Jong-Hoon;Lee, Yeon-Won;Kim, Jae-Hwan
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.230-231
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    • 2005
  • As environmental problems are important, automotive industries are developing various techniques to prevent air pollution. One of these is Positive Crankcase Ventilation (PCV) system. It removes blowby gas which includes about 30% hydrocarbon of total generated quantity. In this system, a PCV valve is attached in a manifold suction tube to control the flow rate of blowby gas which generates differently according to various operating conditions of an automotive engine. As this valve is very important, designers are feeling to design it because of both small size and high velocity. For this reason, we numerically investigated to understand both spool dynamic motion and internal fluid flow characteristics. As the results, spool dynamic characteristics, i.e. displacement, velocity, acting force, increase in direct proportion to the magnitude of differential pressure and indicate periodic oscillating motions. And, the velocity at the orifice region decreases according to the increase of differential pressure because of energy loss which is caused by the sudden decrease of flow area at the orifice region and the increase of flow volume in the front of spool head. Finally, the mass flow rate at the outlet decreases with the increase of spool displacement. We expect that PCV valve designers can easily understand fluid flow inside a PCV valve with our visual information for their help.

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Micro- PIV Measurements of Microchannel Flows and Related Problems (마이크로 채널 내부 유동의 Micro-PIV측정과 제반 문제점)

  • Lee Sang-Joon;Kim Guk-bae
    • 한국가시화정보학회:학술대회논문집
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    • 2002.04a
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    • pp.79-84
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    • 2002
  • Most microfluidic devices such as heat sinks for cooling micro-chips, DNA chip, Lab-On-Chip, and micro pumps etc. have microchannels of various size. Therefore, the design of practical microfluidics demands detail information on flow structure inside the microchannels. However, detail velocity field measurements are rare and difficult to carry out. In addition, as the microfluidics expands, accurate understanding of microscale transport phenomena becomes very important. In this research, micro-PIV system was employed to measure the velocity fields of flow inside a micro-channel. We carried out PIV measurements for several microchannels with varying channels width, inlet and outlet shape, filters, CCD camera and ICCD camera, etc. For effective composition of micro-PIV system, first of all, it is essential to understand optics related with micro-imaging of particles and the particle dynamics encountered in micro-scale channel flows. In addition, it is necessary to find the optimal condition for given experimental environment and? micro-scale flow to be investigated. The problems encountered in measuring velocity field of micro-channel flows are discussed in this paper.

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Separation Performance of Zigzag Air Classifier

  • Hirajima, Tsuyoshi;Nishida, Takuji;Toshima, Ryutaro;Kataoka, Kenji;Tsunekawa, Masami;Asakura, Kuniomi
    • Proceedings of the IEEK Conference
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    • 2001.10a
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    • pp.759-764
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    • 2001
  • The separation performance of zigzag air classifier with angle of 90 degrees was studied using narrow size fractions of thin square samples and granular samples. The simulation results of air velocity inside the classifier indicated that the zigzag geometry induces a new pattern consisting of an upward flow and a circulation flow, Experimental results showed that overflow product recovery was described as an integral calculus of normal distribution as a function of dimensionless air velocity ( $V_{A}$ $V_{A50}$), where $V_{A}$ is superficial air velocity and $V_{A50}$ is the $V_{A}$ at the fifty percent recovery. The $V_{A}$ values were predicted using the equations derived from dynamics for a particle dropping in air. A monitoring system that utilizes changes in acoustic signals emitted during the process of air classification was developed to separate PET with desired recovery or grade. The technical feasibility of the on-line monitoring of the PET recovery and grade was demonstrated by measuring relative energy of the signals.signals.als.

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A study on wind source interpolation based on shape of complex topography (복잡지형 형상에 따른 풍력자원 보정에 관한 연구)

  • Cheang, Eui-Heang;Moon, Chae-Joo;Kim, Eui-Sun;Chang, Young-Hak
    • Journal of the Korean Solar Energy Society
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    • v.29 no.6
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    • pp.62-68
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    • 2009
  • There has been a continuous increase in the utilization and utility value of renewable energy such as wind power generation in modem society. Wind condition is the absolute variable to the energy volume in the case of a wind power generation system. For this reason, wind power generators have already been installed in areas where wind velocity is high and the possibility of danger is very low. In other words, instability is likely if the wind velocity in an area is high and where a wind power generation system can be built. On the contrary, low wind velocity is possible in an area with high stability. Therefore, the design and manufacture of a wind power generation system should be carried out in a more complicated topography in order to secure a bigger market. This study examines and suggest how topography affects wind shear by analyzing the measured data in order to predict wind power generation more reliably.

The geophysical survey and rock classification suitable for the design of a tunnel in urban area passing underneath the Gyeongbu Line(Railload) (경부선 직하부를 나란히 통과하는 도심지 터널에 있어서 지표물리탐사 및 암반등급 평가 사례 연구)

  • Lee Kun;Kim Eun-Duk;Sha Sang-Ho;Cha Young-Ho;Kim Tae-Young;Jung Doo-Suk;Hwang Nak-Yeon
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.673-679
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    • 2005
  • Urban conditions such as underground facilities and ambient noises due to cultural activity restrict the application of conventional geophysical techniques in general. We used the linear array microtremor technique which uses these noises as strong energy source. The result parameter of the survey is shear wave velocity profile which had been applied as an fundamental information for the determination of the rock support type in tunnel design. This study was the first case in Korea which utilized a surface geophysical technique yielding successful result in urban area especially under the existing rail ways. The quantitative relation between the shear wave velocity from this method and the rock mass rating(RMR) determined from the inspection of the cores recovered from the same boreholes showed high statistical relationship. These correlations were then used to relate the shear-wave velocity to RMR along the entire profile.

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A Source Static Correction Algorithm in Crosswell Tomography (시추공 탄성파 자료의 송신기 정보정 알고리즘)

  • Ji Jun
    • Geophysics and Geophysical Exploration
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    • v.5 no.3
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    • pp.193-198
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    • 2002
  • In crosswell ray tomography, the resultant velocity structure could be affected by source static, first-arrival-time picking errors, convergence to a local minimum due to an inappropriate initial velocity model and etc. In the paper, I propose an algorithm that automatically correct the souce static among these error-prone factors. The algorithm automatically corrects source static using the picking times' differences along the source direction. The application of the algorithm to real data produces a quite satisfactory result. Tile algorithm seems to be helpful for users to apply the souce static correction consistently and to acquire accurate velocity structure.

The Research about Free Piston Linear Engine Fueled with Hydrogen using Numerical Analysis (수소를 연료로 사용한 프리피스톤 리니어 엔진의 수치해석에 관한 연구)

  • Nguyen, Ba Hung;Oh, Yong-Il;Lim, Ock-Taeck
    • Journal of Hydrogen and New Energy
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    • v.23 no.2
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    • pp.162-172
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    • 2012
  • This paper presents a research about free piston linear engine (FPLE) fueled with hydrogen, in which, the numerical models are built to simulate the operation during the full stroke of the engine. Dynamic model, linear alternator model and thermodynamic model are used as the numerical models to predict piston velocity, in-cylinder pressure and electric power of FPLE. The spark timing and air gap length are changed to provide information for the prediction. Beside, the heat transfer problem is also investigated in the paper. The results of research are divided by two parts, including motoring mode and firing mode. The result of motoring mode showed that there is validation between simulation and experiment for volume and pressure in cylinder. For firing mode, by increasing spark timing, the velocity of piston, peak pressure and electric power also increase respectively. Beside, when increasing air gap length, the electric power increases accordingly while the motion of piston is not symmetric. The effect of heat transfer also observed clearly by reducing of the peak pressure, velocity of piston and electric power.