• Title, Summary, Keyword: bellow effect

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Investigation of Spark Discharge in Water as a Source of Mechanical Actuation

  • Taylor, Nathaniel D.;Fridman, Gregory;Fridman, Alexander;Dobrynin, Danil
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.258-258
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    • 2014
  • Spark discharge in water generates shockwaves which have been utilized to generate mechanical actuation for potential use in pumping application. Discharge pulses of several microseconds generate shockwaves and vapor bubbles which subsequently displace the water for a period of milliseconds. Through the use of a sealed discharge chamber and metal bellow spring, the fluid motion can be used create an oscillating linear actuator. Continuous actuation of the bellow has been demonstrated through the use of high frequency spark discharge. Discharge in water forms a region of high electric field around the electrode tip which leads to the creation of a thermal plasma channel. This process produces fast thermal expansion, vapor and bubble generation, and a subsequent shockwave in the water which creates physical displacement of the water [1]. Previous work was been conducted to utilize the shockwave effect of spark discharge in water for the inactivation of bacteria, removal of mineral fouling, and the formation of sheet metal [2-4]. Pulses ranging from 25 to 40 kV and 600 to 900 A are generated inside of the chamber and the bellow motion is captured using a slow motion video camera. The maximum displacements measured are from 0.7 to 1.2 mm and show that there is a correlation between discharge energy input to the water and the displacement that is generated. Subsequent oscillations of the bellow are created by the spring force of the bellow and vapor in the chamber. Using microsecond shutter speed ICCD imaging, the development of the discharge bubble and spark can be observed and measured.

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Effect of Slit Ventilation System in Sportswear on Physiological Responses (스포츠웨어의 슬릿 벤틸레이션 시스템이 인체 생리반응에 미치는 효과)

  • Yeon, Soo-Min;Kim, Hee-Eun
    • Fashion & Textile Research Journal
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    • v.7 no.1
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    • pp.75-80
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    • 2005
  • The purpose of this study was to investigate the effects of silt ventilation system on physiological responses. We measured rectal temperature, local skin temperature, clothing microclimate, blood pressure, heart rate, energy metabolism, body weight loss and subjective sensation during 70 minute, 50 min exercise period and 20 min rest period. The five women subjects randomly wore sportswear without slit ventilation system(NS sportswear) and sportswear with slit ventilation system(S sportswear) under the environmental condition of $25^{\circ}C$, 50%RH. The results of this study are as follows; Rectal temperature, mean skin temperature, clothing microclimate, blood pressure, heart rate, energy metabolism and body weight loss were significantly lower level in 'S sportswear'. In 'S sportswear', subjects replied less hot, less uncomfortable and less wet. Slit ventilation system can be used for bellow effect which is meaningful device of convection during exercise. We could find out that 'S sportswear' has advantage in physiological function.

The Static Characteristics of Hydrostatic Journal Bearings (정압저어널 베어링의 정특성 해석)

  • Park, Cheon-Hong;Kim, Seok-Il;Lee, Hu-Sang
    • 한국기계연구소 소보
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    • pp.21-27
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    • 1988
  • In this study, a series of experiments and analyses are performed to estimate the static characteristics of hydrostatic journal bearing such as load capacity, pressure change in each recess, eccentricity of spindle, etc. The experiments are carried out for a multi-recess type journal bearing with capillary restrictor. The Finite Element Method(FEM) is used for the analyses. The predicted load capacity under the condition of stationary or eccentric ratio of bellow 0.2 of the spindle shows excellent agreement with the measured. But, with an increase of the eccentric ratio when the spindle is rotating, the predicted load capacity is largely estimated than the measured. It seems that the difference is mainly caused among others from the fact that the effect of oil-viscosity variation due to the temperature change in the bearing is not introduced into the analyses. The analysis method proposed to estimate the static characteristics of hydrostatic journal bearing is considered to be very reliable since the predicted results are overall in good agreement with the measured.

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Study on the Fluctuations of Groundwater Levels in Cheju Island, Korea (제주도 지하수의 수위변동에 관한 연구)

  • Park, Won-Bae;Yang, Seong-Gi;Go, Gi-Won
    • Journal of Environmental Science International
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    • v.3 no.4
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    • pp.333-348
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    • 1994
  • The groundwater levels at 11 sites and the vertical variations o( the water Quality at 1 site were measured to study the characteristic of the groundwater level fluctuation of Cheju Island. The results of the measurements for the groundwater levels were as follows; In the eastern part, inculding Kimnyong, Jongdal and Sungsan, a sinusoidal fluctuation of groundwater levels occurred in response to oceanic tides. The tidal effect on the groundwater level was reduced depending upon the distance from seashore. But time lag showed that the trend is reversed. However, in the Samyang, Kosan and Shinhyo areas show that the groundwater level was directly influenced by the amount of precipitation. Especially, Shinhyo area which southern part in Cheju was affected the most and show upper parabasal groundwater level. In Susan- I which eastern part in Cheju, well rovealed that water Quality changed with the period of a tide. Salinity at the lim, bellow the natural groundwater level, was approched to the brackish groundwater(1000ppm).

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Analysis on the Relating Factors of Managerial Performance of Local Government Hospitals (지방의료원의 경영성과 관련요인 분석)

  • Lee, Chang-Eun
    • The Korean Journal of Health Service Management
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    • v.3 no.2
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    • pp.1-15
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    • 2009
  • The purpose of this study is to analyze the internal factors that influence the performance of local government hospitals in Korea. There are 34 hospitals in korea as of 2008. Among these hospitals 5 are profit-making and the other loss-making in terms of profitability. Data was collected by Institute of local government hospital union. The major findings of this study was as follows : Firstly, 7 hospitals are high level, over than 100% of fixed ratio. But that result was better than the other study 5 years ago. Secondly, 29 hospitals are bellow 85% of bed occupancy rate. There are a number of hospitals didn't use the facilities and the personnel cost in total costs are high. And lastly, as a result of multiple regression analysis, the factors had on significant effect on normal profit to total assets are personnel cost(-), liability to total assets(-), average length of stay(-), outpatient visits to inpatient days(-). In conclusion, to improve the profitability of hospitals, the efforts to reduce personnel cost and to increase bed occupancy rate.

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Estimation Method of Noise Reducing Devices Installed on the Noise Barrier(3) - Suggestion of Test and Estimation Method - (방음벽 상단소음저감장치의 성능평가 방법에 관한 연구(3) - 시험 및 평가방법의 제안 -)

  • Kim, Chul-Hwan;Chan, Tae-Sun;Kang, Hee-Man;Jeon, Ki-Seong;Kim, Dong-Joon;Chang, Seo-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.496-499
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    • 2008
  • The noise reducing devices installed on the noise barrier have been developed in many shapes and ways to reduce noise around road traffic areas. In this study, test and estimation method for the noise reducing device witch installed on the top of a noise barrier was suggested. For this, the authors have considered sound power flow around the device and sound pressure levels for the far field area. To estimate the area effect behind the barrier, area average of noise pressure level difference divided by two area, upper and bellow the sight-line. Comparing the attenuation difference of these areas, the tendency of noise reduction effect was studied according to type of noise reducing devices. Compared with noise shielding efficiency of the devices that using equivalent height of a simple barrier calculated by the SoundPlan, the commercial environment noise simulation software.

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A Reports on Chronic Dermatitis Treated by fasting Therapy (慢性 皮膚疾患 患者에 對한 節食療法 治驗例)

  • O, Eun-Young;Jee, Seon-Young;Gu, Deok-Mo
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.14 no.1
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    • pp.94-104
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    • 2001
  • A Reports were done on 3 cases of proriasis, 1 case of chronic urticaria which were admition and treated by fasting therapy in Dept. surgery, opthalmology & otolaryngology, college of Oriental Medicine, Kyungsan University, Pohang, Korea, from March 1999 to October 2000. The results were as follows: 1. In the case chronic urticaria, symptom and sign(jtching, wheal, erythema), except of pigment, were showed conciderable improvement. 2. In the case proriasis, it is different of person, bellow 5cm sized erythematous popules were disappeared during fasting therapy, above 5cm sized erythematous papules and plaque were improved by using medication after fasting therapy. Silver-white colored scales was improved about $50-60\%$, itching was disappeared during fasting therapy. 3. After fasting therapy there was a recurrence, but about $40-50\%$ decreased symptoms were showed. 4. Besides upper diagnosis and treatment based on overall of symptoms and signs considered by documentary investigation, medications by Sasang prescription also can be expected good treatment effect.

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Development of 3-axis Loadcell for Measuring the Side Force of MPV Using Design of Experiment (실험계획법을 이용한 다목적 차량의 측면하중 측정을 위한 3축 로드셀 개발)

  • Chu, Sung-Il;Park, Jun-Hyub;Lee, Jin-Gun;Park, Ji-Young
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.4
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    • pp.83-93
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    • 2007
  • This paper represents the development of 3-axises loadcell for measuring the side-force of suspension module of MPV(Multi Purposed Vehicle). The side force causes the failure of damper, such as leakage. The loadcell was developed using strain gauges, and the Wheastone bridge circuit to compensate for the cross-talk between the each axises and the measurement error by temperature. Structure analysis of loadcell was accomplished with FEM(Finite Element Method) to optimize the location of strain gages. The design optimization for important factors that have an effect on performance of loadcell was accomplished by using DOE(Design of Experiment). Loadcell was produced and successfully tested, showing good sensitivity and low cross-talk. The cross-talk of the developed loadcell is bellow 5%. The load history was measured at proving ground. The maximum side-force, the longitudinal force, and vertical force of MPV are 4.2 kN, 8.0 kN, and 17.0 kN, respectively, at Belgian road.

Effect of Wallastonite, Potssium chloride and Potassium sulphate on the mineraligation of Urea (규회석 분말, 염화칼륨 및 황산칼륨이 요소질소의 유효화에 미친 영향)

  • Oh, Wang-Keun;Kim, Jea-Yeang
    • Korean Journal of Soil Science and Fertilizer
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    • v.23 no.4
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    • pp.293-296
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    • 1990
  • The effect of wallastonite, potassium chloride and potassium sulphate on the ammonification and nitrification of urea was studied in a non-planted green house experiment, filling with 500g soil in plastic pot and incubating for 17 days. Potassium sulphate gave superior effect on the neutralizing soil acidity of wallastonite than potassium chloride and raised soil pH which promoted ammonification and subsequent nitrification of urea. Less than 20% $NO_3-N$ against the sum of $NH_4-N$ and $NO_3-N$ was accumulated in soils incubated bellow pH 6.0. It seemed that pH 5.2 to 6.0 was the critical range for the nitrification of ammonium, or raising the concentration of ammonia in soils to the toxic level to the nitrification. It appeared that the nitrification could be occuring in low moisture, air dried, conditions of soil.

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Effect of cold working on the thermal expansion and mechanical properties of Fe-29%-Ni-17%Co low thermal expansion alloy (Fe-29%Ni-17%Co 저열팽창성 합금의 기계적 및 열팽창 특성에 미치는 냉간 가공의 영향)

  • Lee, Kee-Ahn;Kim, Song-Yi;NamKung, Jung;Kim, Mun-Chul
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.355-356
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    • 2009
  • The change of thermal expansion and mechanical behaviors by cold working has been investigated in Fe-29%Ni-17%Co low thermal expansion Kovar alloy. Fe-29%Ni-17%Co alloy was cold rolled gradually and prepared to plates having reduction ratio of 0%, 20%, 40%, 60%, and 80%. Annealing effect on the properties was also studied. Thermal expansion was measured from $25^{\circ}C$ to $600^{\circ}C$ with a heating rate of $5^{\circ}C$/min by using vacuum differential dilatometer. It was found that thermal expansion coefficient ($\alpha_{30{\sim}400}$) slightly decreased (reduction ration of 20%) and then remarkably increased (above reduction ration of 40%) with increasing reduction ratio of cold rolling. Thermal expansion coefficient ($\alpha_{30{\sim}400}$) was sharply decreased after annealing heat-treatment. Yield and tensile strengths were continuously increased and elongation was decreased by cold roiling. Microstructural observation and X-ray diffraction analysis results showed that the $\alpha$ phase significantly increased as the reduction ratio increased. The slight decrease of thermal expansion coefficient bellow reduction ration of 20% could be explained by the destroying short-range ordering and the decreasing of grain size. The significant increase of thermal expansion coefficient with cold rolling mainly attributed to the appearance of $\alpha$ phase. The correlation between the microstructural cause and invar phenomena for the low thermal expansion behavior was also discussed.

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