• Title/Summary/Keyword: Air injection

검색결과 1,200건 처리시간 0.026초

습식 부항 시술시 사혈량에 따른 부항 탈락 위험도 탐색 (Change in Risk of Dropout Due to Bleeding during Bloodletting-Cupping Therapy)

  • 김대혁;배은경;박정환;김소영;이상훈
    • Korean Journal of Acupuncture
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    • 제35권1호
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    • pp.41-45
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    • 2018
  • Objectives : To investigate minimum pressure by verifying changes in pressure due to bleeding amount during bloodletting-cupping therapy. Methods : (1) We compared adhesion performance of four different cupping cups of same size: two disposable cupping cups(A, B) and two reusable cupping cups(A, B) each were vacuumed three times and kept in place for 10 minutes. (2) We vacuumed two different sized disposable cupping cups(A), size.1(InnerDiameter 48.8 mm) and size.3(InnerDiameter 39.1 mm), twice each(-200 mmHg) on silicon plate. We injected water and air at regular intervals in cupping cups by using a syringe, and then measured change of pressure in cupping cups and pressure at the time of dropout. Results : (1) Pressure reduction was $4.75{\pm}2.78%$ on average in the order of 'Disposable[A]>reusable[B]>Disposable[B]>reusable[A]', so that pressure retention performance of disposable cups can't be regarded as inferior to that of reusable cups. (2) Pressure of disposable cupping B(size.1) decreased by an average of -40.08 mmHg per 5 ml of water. At -24.8 mmHg, when 22 ml of water has been injected, cup has come off. Pressure of disposable cupping B(size. 3) decreased by an average of -99.4 mmHg per 5 ml of water. At -48.6 mmHg, when 13 ml of water was injected, cupping came off. Conclusions : Considering reduction rate of pressure due to water injection, in case of bleeding more than 15 ml, size.3 cup always comes off, therefore it needs to be re-operated at least once. Meanwhile, size.1 cup does not always come off in the same condition, depending on the initial pressure and therefore, re-operation may be considered.

화재위치에 따른 $CO_2$소화제 전달특성 (The Transfer Characteristics of $CO_2$ Extinguishant According with the Location of Fire Plume)

  • 박찬수;최주석
    • 한국화재소방학회논문지
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    • 제17권4호
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    • pp.28-35
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    • 2003
  • 선박기관실과 유사한 공간에 $CO_2$ 소화제를 방사하였을 때 화재위치에 따른 $CO_2$ 소화제 전달특성을 분석하기 위하여 전산묘사연구를 수행하였다. 화재위치를 변화시키면서 유동장과 농도장을 계산하였으며, 실험결과 화재화염위치가 유동패턴과 $CO_2$소화제 질량전달특성에 지배적인 영향을 미치는 것으로 나타났다. 1층과 2층으로 구성된 기관실의 2층 중앙 좌측영역에 화재화염이 위치하는 경우에는 에어 커턴과 같은 효과가 화재가 발생한 영역에서 나타났고, 이 영역으로의 질량전달을 방해하였다. 높이에 따른 특성에서는 1, 2충 중앙 좌측영역에 화재가 위치한 경우, $CO_2$소화제가 완전히 분사된 후에도 이 영역에 소화가능한계 이하의 등농도선이 형성되었다. 따라서 본 연구결과들은 $CO_2$소화장치 설비 시 $CO_2$소화제 분사노즐을 배열하는데 고려되어져야 할 것으로 생각된다.

입자크기분석을 위한 레이저회절 분광계의 측정오차 분석 (Analysis of Measuring Error for Particle Size Analysis by Laser Diffraction Spectrometer)

  • 하상안;손희정
    • 대한환경공학회지
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    • 제22권4호
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    • pp.713-722
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    • 2000
  • 본 연구는 입자크기를 분석하기 위한 장치인 레이저회절 분광계의 측정오차 및 재현성을 분석한 것이다. 레이저회절 spectrometers는 입자크기를 분석하기 위한 장치 중에서 가장 대표적이고 중요성을 가진다. 이 측정장치는 운전이 간단하며, 입자분석에 있어서 재현성이 우수하고, 빠른 속도로 분석이 가능한 형태이다. 입자크기를 분석하는 과정에 있어서 공급되는 분산형태와 흐름율에 따라서 측정오차가 미세하게 발생되었고, 흐름율은 분산형태가 건식인 경우 0.1~23 g/min로 공급하였고, 습식인 경우는 분산되는 용매에 따라서 1.4~35 %가 되도록 조절하여 측정결과에 따라서 발생되는 측정오차를 분석하였다. 흐름을 변화에 따라서 발생되는 측정 오차는 측정 cell 내의 입자에 입사되는 레이저 회절패턴이 변화함으로서 측정오차가 다양하게 발생하였다. 본 연구에서 측정오차를 분석하기 위해서는 입자모양, 크기, 분산형태와 용매, 흐름율과 농도의 변화에 따라서 실험을 실행하였고, 분석장치의 시스템에 따른 측정오차를 나타내기 위해서는 장치내의 역학적인 공정, 측정시간, 초점거리, 주입압력, 전처리과정인 ultrasonic이나 혼합에 의한 분산효과에 따라 측정오차 및 재현성을 분석하였다.

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초음속 노즐 출구에 대칭적으로 설치한 추력방향제어장치인 램프 탭의 연구 (An study on the ramp tabs for thurst vector control symmetrically installed at the supersonic nozzle exit)

  • 김경련;고재명;박종호
    • 한국유체기계학회 논문집
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    • 제10권6호
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    • pp.32-37
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    • 2007
  • Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and schlieren system. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

Experimental Investigations on Upper Part Load Vortex Rope Pressure Fluctuations in Francis Turbine Draft Tube

  • Nicolet, Christophe;Zobeiri, Amirreza;Maruzewski, Pierre;Avellan, Francois
    • International Journal of Fluid Machinery and Systems
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    • 제4권1호
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    • pp.179-190
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    • 2011
  • The swirling flow developing in Francis turbine draft tube under part load operation leads to pressure fluctuations usually in the range of 0.2 to 0.4 times the runner rotational frequency resulting from the so-called vortex breakdown. For low cavitation number, the flow features a cavitation vortex rope animated with precession motion. Under given conditions, these pressure fluctuations may lead to undesirable pressure fluctuations in the entire hydraulic system and also produce active power oscillations. For the upper part load range, between 0.7 and 0.85 times the best efficiency discharge, pressure fluctuations may appear in a higher frequency range of 2 to 4 times the runner rotational speed and feature modulations with vortex rope precession. It has been pointed out that for this particular operating point, the vortex rope features elliptical cross section and is animated of a self-rotation. This paper presents an experimental investigation focusing on this peculiar phenomenon, defined as the upper part load vortex rope. The experimental investigation is carried out on a high specific speed Francis turbine scale model installed on a test rig of the EPFL Laboratory for Hydraulic Machines. The selected operating point corresponds to a discharge of 0.83 times the best efficiency discharge. Observations of the cavitation vortex carried out with high speed camera have been recorded and synchronized with pressure fluctuations measurements at the draft tube cone. First, the vortex rope self rotation frequency is evidenced and the related frequency is deduced. Then, the influence of the sigma cavitation number on vortex rope shape and pressure fluctuations is presented. The waterfall diagram of the pressure fluctuations evidences resonance effects with the hydraulic circuit. The influence of outlet bubble cavitation and air injection is also investigated for low cavitation number. The time evolution of the vortex rope volume is compared with pressure fluctuations time evolution using image processing. Finally, the influence of the Froude number on the vortex rope shape and the associated pressure fluctuations is analyzed by varying the rotational speed.

유동가압성형(TPM)을 이용한 휴대용 유도무기용 연소관 조립체 제작공정연구 (A study on the manufacturing of motor case assembly for K-PSAM propulsion system by Trans. power molding(TPM) process)

  • 정상기;윤남균
    • 한국추진공학회지
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    • 제2권3호
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    • pp.107-115
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    • 1998
  • 복합재료와 금속 튜브 사이의 좁고 긴 원통형 공간을 EPDM(Ethylene propylene dien ter polymer)으로 충전하는 연구를 수행하였다. 휴대용 유도무기의 추진기관을 개발하기 위하여 소형 연소관 조립체를 설계하고 제작하였다. 연소관 조립체는 연소관 금속튜브, 연소관 내열재, 그리고 연소관 단열재로 이루어져 있는데 연소관 내열재는 탄소/페놀릭을 사용하여 롤링 공법으로 제작하였으며 연소관 단열재는 EPDM을 사용하여 TPM 공법으로 제작하였다. EPDM의 조성 선정을 위하여 내열 삭마특성, 열분해특성 실험을 수행하였으며 흐름성, 접착성, 경도측정 등을 통하여 최종 조성을 결정하였다. 연소관 조립체를 제작하기 위한 EPDM 충전을 위하여 TPM 공법을 설계하고 금형과 치구를 제작하였다. 충전된 연소관 조립체는 비파괴검사를 통하여 접착, 기공 등을 검사하여 최종 선정되었다.

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중유 싱글 버너 수관식 보일러에서의 합성가스 혼합연소 특성 연구 (A Study on Syngas Co-Combustion Characteristics in a 0.7 MWth Water-Tube Boiler with Single Heavy Oil Burner)

  • 최신영;양동진;방병열;양원
    • 한국수소및신에너지학회논문집
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    • 제21권5호
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    • pp.452-459
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    • 2010
  • This study is aimed to investigate changes of combustion characteristics and heat efficiency when syngas from gasification process using low-rank fuel such as waste and/or biomass is applied partially to an industrial boiler. An experimental study on syngas co-combustion was performed in a 0.7 MW (1 ton steam/hr) water tube boiler using heavy oil as a main fuel. Three kinds of syngas were used as an alternative fuel: mixture gas of pure carbon monoxide and hydrogen, syngas of low calorific value generated from an air-blown gasification process, and syngas of high calorific value produced from an oxygen-blown gasification process. Effects of co-combustion ratio (0~20%) for each syngas on flue gas composition were investigated through syngas injection through the nozzles installed in the side wall of the boiler and measuring $O_2$, $CO_2$, CO and NOx concentrations in the flue gas. When syngas co-combustion was applied, injected syngas was observed to be burned completely and NOx concentration was decreased because nitrogen-containing-heavy oil was partially replaced by the syngas. However, heat efficiency of the boiler was observed to be decreased due to inert compounds in the syngas and the more significant decrease was found when syngas of lower calorific value was used. However, the decrease of the efficiency was under 10% of the heat replacement by syngas.

테들러 백 샘플러의 대체 소재로서 폴리에스터 알루미늄 백에 대한 예비연구: 환원황화합물을 중심으로 (A Preliminary Study on Polyester Aluminum Bag as the Possible Substitute for Tedlar Bag Sampler in RSC Analysis)

  • 김기현;조상희
    • 한국대기환경학회지
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    • 제27권4호
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    • pp.454-459
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    • 2011
  • In this study, the recovery rate of Tedlar bag (T) sampler was investigated in comparison to polyester aluminum bag (P) sampler. To derive the comparative data sets for the relative performance between different samplers, a series of calibration experiments were performed by using 1 ppb standard of four offensive reduced sulfur compounds (RSC) odorants ($H_2S$, $CH_3SH$, DMS, and DMDS) along with $SO_2$ and $CS_2$. All the analysis was made by gas chromatography/pulsed flame photometric detector (GC/PFPD) combined with air server/thermal desorber (AS/TD). The measurement data were obtained by loading gaseous standards (1 ppb) at 3 injection volumes (250, 500 and 1,000 mL) at three intervals (0, 24 and 72 hrs). The recovery rates (RR) of P sampler were computed against the slope values of T sampler. According to our analysis, P sampler exhibits slightly enhanced loss relative to T, especially with light RSCs ($H_2S$ and $CH_3SH$). At day 0, RR for the two were 88 and 85%, respectively. Such reduction proceeded rather rapidly in the case of $H_2S$ through time. However, P sampler was more stable to store $SO_2$ unlike others. Despite slightly reduced recovery, P sampler appears as a good replacement of T sampler.

연료조성에 따른 HCCI 엔진의 냉염 및 열염의 2단연소 특성에 관한 실험적 연구 (An Experimental Study on the Two Stage Ignition of Cool Flame and Hot Flame in HCCI Engine According to Fuel Composition)

  • 이기형;김형민;류재덕;이창식
    • 한국자동차공학회논문집
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    • 제12권1호
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    • pp.17-24
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    • 2004
  • As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However, it is well known that HCCI engines increased HC and CO. Thus, the investigation of combustion characteristics which consists cool and hot flames for HCCI engines were needed to obtain the optimal combustion condition. In this study, combustion characteristics for direct injection type HCCI engine such as quantity of cool flame and hot flame, ignition timing and ignition delay were investigated to clarify the effects of these parameters on performance. The results revealed that diesel combustion showed the two-stage ignition of cool flame and hot flame, the rate of cool flame increase and hot flame decrease with increasing intake air temperature. On the other hand, the gasoline combustion is the single-stage ignition and ignition timing is near the TDC. In addition mixed fuel combustion showed different phenomenon, which depends on the ratio of gasoline component. Ignition timing of mixed fuel is retarded near the TDC and the ignition delay is increased according to ratio of gasoline.

DEVELOPMENT AND IMPLEMENTATION OF DISTRIBUTED HARDWARE-IN-THE-LOOP SIMULATOR FOR AUTOMOTIVE ENGINE CONTROL SYSTEMS

  • YOON M.;LEE W.;SUNWOO M.
    • International Journal of Automotive Technology
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    • 제6권2호
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    • pp.107-117
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    • 2005
  • A distributed hardware-in-the-loop simulation (HILS) platform is developed for designing an automotive engine control system. The HILS equipment consists of a widely used PC and commercial-off-the-shelf (COTS) I/O boards instead of a powerful computing system and custom-made I/O boards. The distributed structure of the HILS system supplements the lack of computing power. These features make the HILS equipment more cost-effective and flexible. The HILS uses an automatic code generation extension, REAL-TIME WORKSHOP$^{ (RTW$^{) of MATLAB$^{ tool-chain and RT-LAB$^{, which enables distributed simulation as well as the detection and generation of digital event between simulation time steps. The mean value engine model, which is used in control design phase, is imported into this HILS. The engine model is supplemented with some I/O subsystems and I/O boards to interface actual input and output signals in real-time. The I/O subsystems are designed to imitate real sensor signals with high fidelity as well as to convert the raw data of the I/O boards to the appropriate forms for proper interfaces. A lot of attention is paid to the generation of a precise crank/ earn signal which has the problem of quantization in a conventional fixed time step simulation. The detection of injection! command signal which occurs between simulation time steps are also successfully compensated. In order to prove the feasibility of the proposed environment, a simple PI controller for an air-to-fuel ratio (AFR) control is used. The proposed HILS environment and I/O systems are shown to be an efficient tool to develop various control functions and to validate the software and hardware of the engine control system.