• Electrical & Electronic Materials
• /
• v.10 no.9
• /
• pp.889-894
• /
• 1997

A miniaturized wind-mill type ultrasonic motor which has diameter in 12.7 mm and thickness in 2.0mm using PMN-PZT piezoelectric ceramics was fabricated. The wind-mill type ultrasonic motors has only three plate and of two wind-mill shape slotted metal endcaps a rotor whose end is hollowed out so that its periphery fits with the shape of the stator and a bearing to guide the rotor. A Finite Element Analysis was carried out to obtain the endcaps behavior under a radial displacement change of piezoelectric disk and to optimize the structure of the number of slots. Increasing the applied voltage the revolution speed of ultrasonic motors was increased. The maximum speed of 700 rpm and the maximum torque of 0.22 nN·m of the wind-mill type ultrasonic motors were obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.373-376
• /
• 2000

The modified Moonie(Cymbal) transducer has been investigated for an accelerometer application. This paper present a wind-mill type ultrasonic motors using ternary piezoelectric ceramics and aluminum endcaps applied by cymbal transducer. The maximum displacement was increased depend on applied voltage and layer number. The multi-layer was fabricated by tape casting using doctor-blade process. The maximum displacement of multi-layered ultrasonic motor was much higher than that of one-layered.

• Journal of Korea Foundry Society
• /
• v.26 no.6
• /
• pp.258-266
• /
• 2006

The purpose of this study was to investigate the effects of silicon and nickel additions that influenced the impact and tensile properties of heavy section as-cast ductile irons for wind mill. Based on the results of the metallographic analysis and the mechanical testing on the 2.0 wt.%Si (LS group) and 2.4 wt.%Si (HS group) ductile irons, which contains 0.0, 0.3, 0.6 and 0.9 wt.%Ni, respectively, the following conclusions could be obtained. The nickel additions increased the tensile properties, the microhardness of pearlite, and the pearlite fraction of matrix for the specimen with the same silicon content. The mechanical properties of LS group specimen were in the range of the specification for the ductile iron wind mill castings. The LS group specimens showed higher absorbed impact energy at room temperature and $-20^{\circ}C$ than that of the HS group specimens. However, the absorbed impact energy at $-20^{\circ}C$ for the HS group specimens was observed to be sharply decreased under 10 J by addition of the nickel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.181-183
• /
• 2000

Ultrasonic Motors of Wind-Mill type(diameter in 11.35mm, thickness in 2.8mm, and 1.44g weight) using Piezoelectric Ceramics have been developed. In recent study, Maximum torque in 100$V_{max}$, 105.8kHz was 7.2 ${\mu}$N$.$m, and bidirectional revolution using single-phase AC was presented. However, it is difficult to use because of small torque. Thus, in present study, new type of Wind -Mill Type Ultrasonic Motor of was designed as stator' structure was changed

• Journal of the KSME
• /
• v.29 no.1
• /
• pp.12-13
• /
• 1989

분쇄도구는 점차수차, 풍차 그리고 증기기관이란 동력기술과 맞물려 제분공정이 대규모화되어 지배자는 이를 독점, 집중화시켜 마침내 공장제도의 원형이 이루어졌던 것이다. 여기서 우리는 wind mill, water mill, rolling mill, miller, milling M/C 등 단어가 뜻하듯 단순히 "제분하는 기계" 뿐만 아니라 "자연력으로 구동되는 기계설비를 사용하였던 모든 Manufacture"라는 것을 공통어 밀(mill)에서 엿볼 수가 있다. James Watt의 증기기관이 실용 중에도 한동안 수차는 산 업 여러 분야에서 동력원으로 자리를 지켜 왔지만 현재는 획기적으로 성능이 좋은 Francis, Pelton, 및 Ossberger 수차가 상업발전소에서 쉬지 않고 돌아가고 있다. 통차, 동미차, 번차, 수대, 연애, 파쇄 등 전통적인 수차와 석구가 기본이 되어 분명히 근세 생산기계설비를 발명케 하였고 동력원으로서 화려한 전성기를 누렸다. 지금은 역사속에 잊혀져 가지만 우리는 시골 산간에서 돌아가는 물레방아의 수연한 고태를 볼 때면 민속문화학, 그리고 기술사적 측면에서 문화재로서의 명맥을 기려 잘 보존할 의무가 절실하다고 생각한다. 보존할 의무가 절실하다고 생각한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.11a
• /
• pp.231-234
• /
• 1998

In this study, the wind-mill type ultrasonic motor was fabricated, and then resonant frequency and vibration velocity characteristics of the stator were measured. Brass metal was pressed with umbrella-type using metal mold, then slot of 4 kind was processed in each of thickness. Among sixteen's stators, resonant frequency on vibration velocity was decreased remarkably in stator of higher resonant point, but resonant frequency on vibration velocity wasn't almost changed at lower resonant point of stator. The thickener thickness of elastic body, vibration velocity was decreased. The more slot of elastic body, vibration velocity was increased Applied voltage was changed from 10$V_{max}$ to 100$V_{max}$. Maximum vibration velocity value was 2.0[m/s].

• Advances in Energy Research
• /
• v.4 no.1
• /
• pp.47-68
• /
• 2016

A well designed hybrid power system (HPS) can deliver electrical energy in a cost effective way. In this paper, model for HPS consisting of photo voltaic (PV) module and wind mill as renewable energy sources (RES) and solar lead acid battery as storage device connected to unidirectional grid is developed for peak demand reduction. Life time energy cost of the system is evaluated. One year hourly site condition and load pattern are taken into account for analysing the HPS. The optimal HPS is determined for least life time energy cost subject to the constraints like state of charge of the battery bank, dump load, renewable energy (RE) generation etc. Optimal solutions are also found out individually for PV module and wind mill. These three systems are compared to find out the most feasible combination. The results show that the HPS can deliver energy in an acceptable cost with reduced peak consumption from the grid. The proposed optimization algorithm is suitable for determining optimal HPS for desired location and load with least energy cost.

• Asian Journal of Turfgrass Science
• /
• v.18 no.1
• /
• pp.29-36
• /
• 2004

The efficient refinement of seed is required to reduce the cost and labor input in artificial propagation of wild plant. This study was carried out to develop methods for collecting and refining tiny seeds from wild plants. For obtaining Phragmites communis seeds, the inflorescence was cut into small fragments using a Straw Cutter and subsequently detached pappus hairs from seed coat by Hammer Mill. The primary refined seeds were passed 1.0 mm sieve. The screened seeds were subjected to Seed Blower with wind speed of 0.25 mㆍsec-1 to collected intact and well-ripen seeds. The seeds of Imperata cylindrica were refined as follows. Inflorescences were cut using a Straw Cutter first. The pappus was removed from cut fragments using a Hammer Mill and subsequently subjected to Seed Scarifier at 500rpm for 60 sec. for further separation. The separated seeds were passed 1.0 mm screen and collected after blowing with Seed Blower of wind speed of 0.15 mㆍsec-1. When the amount of seed was too little to refine with Seed Scarifier and Blower, the procedure was slightly modified from the procedure described above. The crude seed mixture obtained from Hammer Mill step was hand-refined roughly and then immersed into cone. (95%) sulfuric acid for 2 min. and collected floating portion after dilution of sulfuric acid solution 100 times with tap water. The collected seeds were dried and passed 0.149 mm sieve. During seed refining process using mechanical or sulfuric acid treatments, a small portion of damaged seed were evolved, however, the amount was not noticeable as compared to the total amount of collected seeds. Because the germination percentages between hand-refined seeds and seeds refined by above methods were not statistically different, the developed procedures for refining tiny seed of wild plants are helpful to reduce the cost and labor input in artificial propagation of two species.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.147-154
• /
• 2010

The world is gradually running short of fossil fuel. Currently, the role of wind turbine is attracting great attention from all over the world. The objective of this study is to investigate blades of Vertical-axial wind turbine (VAWT) for optimum design using the CFD from the aerodynamics point of view. Because one of the performance of wind turbine depends on shape of blades, the study of comparing one gyro mill type blade and a modified one was carried out. Using the results of computation, we calculated and compared RPM for both models at same wind velocity. And we calculated angular acceleration and moment of inertia to find torque in every time-step. And the pressure contour and velocity profile around the blade were analyzed Also, this study is performed to calculate the wake effect.

• Agricultural and Biosystems Engineering
• /
• v.6 no.2
• /
• pp.65-69
• /
• 2005

A windheat generation system with a Savonius windturbine was developed and the performance was evaluated through field tests. The system consisted of a heat generation drum, heat exchanger, water storage tank, and two circulation pumps. Frictional heat is created by rotation of a rotor inside the drum containing thermo oil, and was used to heat water. In order to estimate the capacity of this windheat generation system, weather data was collected for one year at the site near the windheat generation system. Wind Power from the savonius wind turbine mill was transmitted to the heat generation system with an one-to-three gear system. Starting force to rotate the savonius wind turbine and the whole system including the windheat generation system were 1.0 and 2.5 kg, respectively. Under the outdoor wind condition, maximum speed of the rotor in the drum was 75rpm at wind speed 6.5 m/sec, which was not fast enough to produce heat for greenhouse heating. Annual cumulative hours for wind speeds greater than 5 m/sec at height of 10, 20, 30 m were 190, 300 and 1020 hrs, respectively. A $5^{\circ}C$ increase in water temperature was achieved by the windheat generation system under the tested wind environment.