• 제목/요약/키워드: Air injection

검색결과 1,200건 처리시간 0.026초

STUDY OF CORRELATION BETWEEN WETTED FUEL FOOTPRINTS ON COMBUSTION CHAMBER WALLS AND UBHC IN ENGINE START PROCESSES

  • KIM H.;YOON S.;LAI M.-C.
    • International Journal of Automotive Technology
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    • 제6권5호
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    • pp.437-444
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    • 2005
  • Unburned hydrocarbon (UBHC) emissions from gasoline engines remain a primary engineering research and development concern due to stricter emission regulations. Gasoline engines produce more UBHC emissions during cold start and warm-up than during any other stage of operation, because of insufficient fuel-air mixing, particularly in view of the additional fuel enrichment used for early starting. Impingement of fuel droplets on the cylinder wall is a major source of UBHC and a concern for oil dilution. This paper describes an experimental study that was carried out to investigate the distribution and 'footprint' of fuel droplets impinging on the cylinder wall during the intake stroke under engine starting conditions. Injectors having different targeting and atomization characteristics were used in a 4-Valve engine with optical access to the intake port and combustion chamber. The spray and targeting performance were characterized using high-speed visualization and Phase Doppler Interferometry techniques. The fuel droplets impinging on the port, cylinder wall and piston top were characterized using a color imaging technique during simulated engine start-up from room temperature. Highly absorbent filter paper was placed around the circumference of the cylinder liner and on the piston top to collect fuel droplets during the intake strokes. A small amount of colored dye, which dissolves completely in gasoline, was used as the tracer. Color density on the paper, which is correlated with the amount of fuel deposited and its distribution on the cylinder wall, was measured using image analysis. The results show that by comparing the locations of the wetted footprints and their color intensities, the influence of fuel injection and engine conditions can be qualitatively and quantitatively examined. Fast FID measurements of UBHC were also performed on the engine for correlation to the mixture formation results.

Defect Diagnosis of Cable Insulating Materials by Partial Discharge Statistical Analysis

  • Shin, Jong-Yeol;Park, Hee-Doo;Lee, Jong-Yong;Hong, Jin-Woong
    • Transactions on Electrical and Electronic Materials
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    • 제11권1호
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    • pp.42-47
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    • 2010
  • Polymer insulating materials such as cross linked polyethylene (XLPE) are employed in electric cables used for extra high voltage. These materials can degrade due to chemical, mechanical and electric stress, possibly caused by voids, the presence of extrinsic materials and protrusions. Therefore, this study measured discharge patterns, discharge phase angle, quantity and occurrence frequency as well as changes in XLPE under different temperatures and applied voltages. To quantitatively analyze the irregular partial discharge patterns measured, the discharge patterns were examined using a statistical program. A three layer sample was fabricated, wherein the upper and lower layers were composed of non-void XLPE, while the middle layer was composed of an air void and copper particles. After heating to room temperature and $50^{\circ}C$ and $80^{\circ}C$ in silicone oil, partial discharge characteristics were studied by increasing the voltage from the inception voltage to the breakdown voltage. Partial discharge statistical analysis showed that when the K-means clustering was carried out at 9 kV to determine the void discharge characteristics, the amount discharged at low temperatures was small but when the temperature was increased to $80^{\circ}C$, the discharge amount increased to be 5.7 times more than that at room temperature because electric charge injection became easier. An analysis of the kurtosis and the skewness confirmed that positive and negative polarity had counterclockwise and clockwise clustering distribution, respectively. When 5 kV was applied to copper particles, the K-means was conducted as the temperature changed from $50^{\circ}C$ to $80^{\circ}C$. The amount of charge at a positive polarity increased 20.3% and the amount of charge at a negative polarity increased 54.9%. The clustering distribution of a positive polarity and negative polarity showed a straight line in the kurtosis and skewness analyses.

Experiments on Sedimentation of Particles in a Water Pool with Gas Inflow

  • Kim, Eunho;Jung, Woo Hyun;Park, Jin Ho;Park, Hyun Sun;Moriyama, Kiyofumi
    • Nuclear Engineering and Technology
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    • 제48권2호
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    • pp.457-469
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    • 2016
  • During the late phase of severe accidents of light water reactors, a porous debris bed is expected to develop on the bottom of the flooded reactor cavity after breakup of the melt in water. The geometrical configuration, i.e., internal and external characteristics, of the debris bed is significant for the adequate assessment of the coolability of the relocated corium. The internal structure of a debris bed was investigated experimentally using the DAVINCI (Debris bed research Apparatus for Validation of the bubble-Induced Natural Convection effect Issue) test facility. Particle sedimentation under the influence of a two-phase natural convection flow due to the decay heat in the debris bed was simulated by dropping various sizes of particles into a water vessel with air bubble injection from the bottom. Settled particles were collected and sieved to obtain the particle mass, size distribution in the radial and axial positions, and the bed porosity and permeability. The experimental results showed that the center part of the particle bed tended to have larger particles than the peripheral area. For the axial distribution, the lower layer had a higher fraction of larger particles. As the sedimentation progressed, the size distribution in the upper layers can shift to larger sizes because of the higher vapor generation rate and stronger flow intensity.

상용 소독제의 살균력 및 균 소장 상태 검정 (The study on sterilization effect of disinfectants and detection of bacteria)

  • 송규남
    • 대한간호
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    • 제37권2호
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    • pp.77-86
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    • 1998
  • Yeung Nam University Medical Center, Department Of Central medical Supply Background: The adverse effect of intravenous therapy combined with various complications. Because sterilization technique and appropriate nursing care can prevent various complications, it is important to use appropriate sponge in intravenous therapy. The purpose of study was to identy sterilization effect and detection of bacteria and to provide basic data for use of appropriate disinfectants. Methods: From May 15 1995 to Aug. 3. 1995, disinfectants that were used in Yeung Nam University Medical Center were tested by bacteria culture. To test sterilization effect of disinfectants of intravenous injection sites after disinfection, 10 subjects were used and were tested by bacteria culture for the study. Results: 1) By sterilization effect of disinfectants, bacteria were increased from 103 to 10 from 48 hours in both 2% Zephanon and 2% zephanon that was sterilized by steam, from 10 to 10 from 72 hours and 10 from 48 hours in 70% lsoprophyl alchol. Also, bacterias were detected in 70% lsoprophyl alchol on 48 hours. 2) By stenlization effect of sponge that were used in nursing unit, bacterias were detected in 2% Zephanon on 2 hours, 70% lsoprophyl alchol on 2 hours, 70% lsoprophyl alchol on 8 hours and 70% lsoprophyl alchol on 48 hours. 3) By sterilization effect and detection of bacteria of intravenous site after disinfection, bacterias were detected in 10 of 10 control groups, 8 of 10 sites that were disinfected by steam sterilized 2% zephanon sponge, 6 of 10 sites that were disinfected by 70% lsoprophyl alchol and 4 of 10 sites that were disinfected by 10% Batadine. Conclusions : it is conclued that 70% lsoprophyl alchol is appropriate for intravenous therapy and 10% Betadine is appropriate in ward that were polluted the air and in immunodeficient patients.

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중추성 요붕증이 동반된 랑게르한스 세포 조직구증 1예 (Langerhans Cell Histiocytosis with Central Diabetes Insipidus : A Case Report)

  • 김진호;문준성;문선중;이지은;최재원;은미정;천경아;조인호;윤지성;원규장;이경희;신덕섭;이형우
    • Journal of Yeungnam Medical Science
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    • 제22권2호
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    • pp.259-265
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    • 2005
  • Central diabetes insipidus (DI) is a syndrome characterized by thirst, polydipsia and polyuria. Langerhans cell histiocytosis is one of the etiologies of DI. Recently we experienced a central DI associated with Langerhans cell histiocytosis. The 44 years old female patient complained right hip pain, polydipsia and polyuria. We carried out water deprivation test. After vasopressin injection, urine osmotic pressure was increased from 109 mOsmol/kg to 327 mOsmol/kg (300%). Brain MRI showed a thickened pituitary stalk and air bubble like lesions sized with 5cm, 7cm was shown on fifth L-spine and right hip bone at hip bone CT. CT guided biopsy revealed abnormal histiocytes proliferation and abundant lymphocytes. The final diagnosis was central DI associated with systemic Langerhans cell histiocytosis invading hip bone, L-spine and pituitary stalk. Desmopressin and etoposide chemotherapy were performed to the patient.

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유동 및 응고해석을 이용한 주조방안설계-자동차용 부품(오일팬_BJ3E) (Casting Layout Design Using Flow & Solidification Analysis-Automotive Part(Oil Pan_BJ3E))

  • 권홍규
    • 산업경영시스템학회지
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    • 제42권1호
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    • pp.1-7
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    • 2019
  • In the modern industrial period, the introduction of mass production was most important progress in civilization. Die-casting process is one of main methods for mass production in the modern industry. The aluminum die-casting in the mold filling process is very complicated where flow momentum is the high velocity of the liquid metal. Actually, it is almost impossible in complex parts exactly to figure the mold filling performance out with the experimental knowledge. The aluminum die-castings are important processes in the automotive industry to produce the lightweight automobile bodies. Due to this condition, the simulation is going to be more critical role in the design procedure. Simulation can give the best solution of a casting system and also enhance the casting quality. The cost and time savings of the casting layout design are the most advantage of Computer Aided Engineering (CAE). Generally, the relations of casting conditions such as injection system, gate system, and cooling system should be considered when designing the casting layout. Due to the various relative matters of the above conditions, product defects such as defect extent and location are significantly difference. In this research by using the simulation software (AnyCasting), CAE simulation was conducted with three layout designs to find out the best alternative for the casting layout design of an automotive Oil Pan_BJ3E. In order to apply the simulation results into the production die-casting mold, they were analyzed and compared carefully. Internal porosities which are caused by air entrapments during the filling process were predicted and also the results of three models were compared with the modifications of the gate system and overflows. Internal porosities which are occurred during the solidification process are predicted with the solidification analysis. And also the results of the modified gate system are compared.

확장형 이중패커를 이용한 지하수 공벽과 내부케이싱의 구간차폐 그라우팅 기술에 대한 연구 (A Study on Grouting Technology Using Expansion Double Packers for Sectional Blocking between Groundwater Borehole and Inner Casing)

  • 조희남;최성욱;박종오;배세달;이병용;최상일
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제24권1호
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    • pp.35-42
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    • 2019
  • In installation of groundwater wells, grouting materials are injected between the groundwater borehole and the inner casing in order to prevent infiltration of contaminated groundwater from the top soil layers into wells. The injection device of grouting materials is commonly composed of an inlet head device with an expansion packer, a cylinder capable of storing the grouting materials, and an air cylinder. In this work, two types of common grouting materials, silicon and cement materials, were tested for their performances as grouting media. For silicon. silicon was mixed with clay or calcite, and tested for their tensile strength and underwater reactivity. Both silicon-clay and silicon-calcite mixtures had adequate flow and adhesiveness. For cement material, general cement, ultra-rapid harding cement, and natural cement were respectively mixed with three different soil types including coarse-grained granite, fine-grained granite, and gneiss, and direct shearing tests were conducted after hardening. Under grouting depth condition of 30 m, the minimum adhesive strength was greater for weathered gneiss than non-weathered gneiss with its maximum values obtained from the mixtures of ultra rapid-harding cement.

균일류에서 프로펠러 앞날 근처 관통구가 모형 프로펠러 캐비테이션에 미치는 영향 (Influence of Thru Holes Near Leading Edge of a Model Propeller on Cavitation Behavior)

  • 안종우;박일룡;박영하;김제인;설한신;김기섭
    • 대한조선학회논문집
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    • 제56권3호
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    • pp.281-289
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    • 2019
  • In order to investigate the influence of thru holes near leading edge of model propeller on cavitation behavior, a model propeller with thru holes was manufactured and tested at Large Cavitation Tunnel (LCT). The pressure distribution around the thru hole on propeller blade was numerically calculated to help understand the local flow characteristics related to cavitation behavior. The model propeller is a five bladed propeller which has 2 blades with thru holes and 3 blades with smooth surface. The cavitation observation tests were conducted at angles of $0^{\circ}$ & $6^{\circ}$ using an inclined-shaft dynamometer in LCT. There are big difference on the suction side cavitation behavior each other due to the existence of thru hole. While the blades with thou holes start generation of the sheet cavitation from the leading edge on the suction side, the blades with smooth surface generate the cloud cavitation from the mid-chord. Cavitation on the blades with thru holes shows more similar behavior to those of the full-scale propeller of which the pipe line for air injection is closed. The numerical analysis result shows that the sharp pressure drop occurs around thru holes on the blade. Consequently, the thru hole around leading edge stimulates the cavitation occurrence and stabilizes the cavitation behavior. Based on these results, the effect of thru holes on propeller cavitation behavior behind a model ship should be studied in the future.

단상 영구자석 동기 전동기의 가상 dq축 기반 초기 회전자 자극 검출 (Initial Rotor Polarity Detection of Single-phase Permanent Magnet Synchronous Motor Based on Virtual dq-axis)

  • 서승우;황선환;이기창
    • 전기전자학회논문지
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    • 제24권4호
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    • pp.1004-1010
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    • 2020
  • 본 논문은 단상 영구자석 동기전동기의 초기 회전자 자극 검출 기법을 제안한다. 대상 전동기는 저속 및 정지 상태에서 역기전력을 기반으로 위치 정보를 얻을 수 없다. 따라서 초기 개루프 기동이 필요하며 이 과정에서 저 전류 및 소프트 기동을 위한 초기 회전자 위치 정보가 필요하다. 제안하는 초기 회전자 자극 검출 알고리즘의 경우 비대칭 공극의 영향 및 영구자석 자속의 영향을 고려하였으며, 고주파 전압 신호 주입을 기반으로 정확한 검출을 위한 오프셋 전압을 이용하였다. 이때 고주파 전압 신호로부터 유도된 고주파 전류의 경우 가상의 dq축을 이용하여 유도된 전류의 최댓값 취득을 통해 회전자 영구자석 자극을 판별한다. 본 논문에서는 센서리스 운전의 저전류 및 소프트 기동을 위해 제안된 초기 회전자 자극 검출 알고리즘을 홀센서 신호를 근거로 효용성 및 타당성을 다수의 실험을 통해 검증하였다.

회동수원지의 정수처리 공정을 위한 DAF pilot plant 운영 성능평가 (Operation evaluation of DAF pilot plant for water treatment process in Hoedong Reservoir)

  • 맹민수;;김동현;신귀암;독고석
    • 상하수도학회지
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    • 제34권6호
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    • pp.463-471
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    • 2020
  • A 1,000 ㎥/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 ㎛ showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.