• Title/Summary/Keyword: pressure relation

검색결과 1,012건 처리시간 0.029초

The Kennicutt-Schmidt relation of the ram pressure stripped gas

  • Lee, Bumhyun;Chung, Aeree
    • 천문학회보
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    • 제42권2호
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    • pp.75.1-75.1
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    • 2017
  • Ram pressure due to the intracluster medium (ICM) is known to play a crucial role in removing the cool gas content of a galaxy on a short timescale, potentially driving a star forming galaxy to evolve into a red passive population. Although many HI imaging studies find clear evidence of diffuse atomic gas stripping from cluster galaxies, it is still debatable whether the ram pressure can also strip dense molecular gas. NGC 4522, a Virgo spiral, undergoing strong ram pressure stripping, is one of the few cases where extraplanar CO emission together with stripped HI gas and $H{\alpha}$ knots has been identified, providing an ideal laboratory to study the molecular gas stripping event and the extraplanar star formation activity. The aim of this work is to investigate the origin of extraplanar molecular clouds near NGC 4522 (e.g. stripped or forming in situ), and to probe a relation between the molecular gas surface density and the star formation rate (i.e. the Kennicutt-Schmidt law) at sub-kpc scale, especially in the extraplanar space, using ALMA Cycle 3 CO data and $H{\alpha}$ data of NGC 4522. We present the results from our ALMA observations, and discuss possible scenarios for the origin of extraplanar molecular clouds and to characterize the star formation activity associated with stripped gas outside the galactic disk.

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안쪽축이 회전하는 환형관내 헬리컬 유동장의 실험적 연구 (Experimental Study on the Helical Flow Field in a Concentric Annulus with Rotating Inner Cylinders)

  • 황영규;김영주
    • 대한기계학회논문집B
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    • 제24권6호
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    • pp.822-833
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    • 2000
  • This experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure drops and skin-friction coefficients have been measured for the fully developed flow of water and that of glycerine-water solution (44%) at a inner cylinder rotational speed of $0{\sim}600$ rpm, respectively. The transitional flow has been examined by the measurement of pressure drops and the visualization of flow field, to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients and to understand the flow instability mechanism. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure drops and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, it is gradually declined for turbulent flow regime. Consequently, the critical (axial-flow) Reynolds number decreases as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the excitation of taylor vortices.

예혼합 압축 착화 엔진용 고압 인젝터의 분무특성과 분사조건 최적화에 관한 기초 연구 (The basic study of spray characteristics and optimal fuel injection for high pressure injector in homogeneous charge compression ignition engine)

  • 류재덕;김형민;이기형;이창식
    • 한국분무공학회지
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    • 제9권1호
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    • pp.30-36
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    • 2004
  • The purpose of this study was to investigate the fuel spray characteristics that made most important at an homogeneous air fuel mixture, in a common rail direct injection type HCCI engine. As a study conducted relation which a back pressure and injection pressure are influenced to air fuel mixture characteristics, we tried to offer date even through we select suitable to a HCCI engine running condition of the fuel injection condition. To accomplish the study, to measure a injection rate of common rail type injector and to visualize and simulate a fuel spray was conducted. From the result of injection rate, a common rail injector was confirmed to appear a initial delay of 0.3msec and a latter period delay of 0.7msec. Therefore, real injection duration was determined by about 0.5msec increasing. From the result of fuel spray, the spray penetration was proportional to 1/4 exponent of atmosphere pressure. An experimental equation was deduced from the spray penetration of spray visualization experiment and the relation of injection duration and penetration was estimated in HCCI engine using an experimental equation.

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ISIS 시스템을 이용한 최적 그라우팅 시스템 개발 연구 (A Study to Develop Optimal Injection System Using ISIS(the In-situ Soil Injection Simulator))

  • 천병식;김진춘;김경민;이민호;이정훈;김진수;박종근
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2002년도 봄 학술발표회 논문집
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    • pp.619-626
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    • 2002
  • In this study, a correlation among pressure, time and quantity of injection was organized from the laboratory tests, which were executed many times representing in-situ soil conditions carefully and then it would be applied to the in-situ soil injection simulator which will be developed for optimal injection into the ground. The sort of sample soils were both sand(A specimen) and silty sand(B specimen). Injection tests were gone into operation by compaction state, injection velocity and the depth individually. In the ground improved with permeation Infection, the relation among injection pressure of the same depth, the injected quantities and time were systematic by the depth. By defining the limit range of injection pressure and quantity about the variety of a linear equation obtained from lining each of their trend, the application of laboratory injection monitoring program and the data to evaluate its realization were produced. In the ground improved with root type injection, the relation between injection pressure and the injected quantities was irregular because fracture state occurred quickly.

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전통주거(傳統住居) 공간의 생리적(生理的) 특성(特性)에 관한 연구 - 전북지방 농촌주택(農村住宅)을 중심으로 - (A study on the Physiological Character of living Space in Traditional Koaean House - Focsed on the rural house in Chonbuk province -)

  • 김용집
    • 건축역사연구
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    • 제8권2호
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    • pp.59-72
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    • 1999
  • The purpose of this study is to find the spatial factors, strucure of living and activity in traditional Korean house through the Phiysiological view, Spatial factors of the house are concerned to the interior environment and sanitary condition, The elements of respiratory, nerve, temperature sence. vision, hearing, smelling have good condition and touch, pressure sence, pain, metabolism are poor in the house, Ventilation, Lighting, pleasant condition of interior environment are concerned to the elements that mentioned above and have most important meaning in the relation rate of space as 1st factor. And 2nd factor is for metabolism, housework and rest, 3rd factor ie for temperature sence, privacy and reproduction. The relation rate of factors concering interior environment are high in the upper class house. Anbang has important meaning in the relation of living structure and relation sequence of space is anbang, Konnonbang, kitchen, toilet, water place, auxiliary buildings. The relation rate of activity is high in interior space in winter and exterior space in summer.

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파랑-구조물-지반 상호작용에 의한 혼성제 주변 해저지반의 3차원 동적응답 특성 (3-D Dynamic Response Characteristics of Seabed around Composite Breakwater in Relation to Wave-Structure-Soil Interaction)

  • 허동수;박종률;이우동
    • 한국해양공학회지
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    • 제30권6호
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    • pp.505-519
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    • 2016
  • If the seabed is exposed to high waves for a long period, the pore water pressure may be excessive, making the seabed subject to liquefaction. As the water pressure change due to wave action is transmitted to the pore water pressure of the seabed, a phase difference will occur because of the fluid resistance from water permeability. Thus, the effective stress of the seabed will be decreased. If a composite breakwater or other structure with large wave reflection is installed over the seabed, a partial standing wave field is formed, and thus larger wave loading is directly transmitted to the seabed, which considerably influences its stability. To analyze the 3-D dynamic response characteristics of the seabed around a composite breakwater, this study performed a numerical simulation by applying LES-WASS-3D to directly analyze the wave-structure-soil interaction. First, the waveform around the composite breakwater and the pore water pressure in the seabed and rubble mound were compared and verified using the results of existing experiments. In addition, the characteristics of the wave field were analyzed around the composite breakwater, where there was an opening under different incident wave conditions. To analyze the effect of the changed wave field on the 3-D dynamic response of the seabed, the correlation between the wave height distribution and pore water pressure distribution of the seabed was investigated. Finally, the numerical results for the perpendicular phase difference of the pore water pressure were aggregated to understand the characteristics of the 3-D dynamic response of the seabed around the composite breakwater in relation to the water-structure-soil interaction.

일부 성인남녀의 무기질 (Ca, P, Fe, Na, K, Zn) 섭취와 혈압 및 혈중 지질과의 관련성 (Relation among Mineral (Ca, P, Fe, Na, K,Zn) Intakes, Blood Pressure, and Blood Lipids in Korean Adults)

  • 최미경;이원영;박정덕
    • Journal of Nutrition and Health
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    • 제38권10호
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    • pp.827-835
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    • 2005
  • The purpose of this study was to investigate the relation among mineral intakes, blood pressure, and blood lipids for health management of Korean adults over 20 years old. Subjects were recruited from the district where they lived, which included rural (Yoju, n = 137) , coastal (Taean, n = 100) , and urban district (Suwon, n : 117) . hnthropornekical measurement, blood pressure measurement, dietary intake assessment using 24-hour recall method, and blood collection and analysis of blood lipids were conducted. The average age, height, weight, and BMI were 54.1 years, 168.5 cm, 67.3 kg, and 24.5 kg/$m^{2}$ for men and 53.9 years,153.8 cm,59.2 kg, and 25.0 kg/$m^{2}$ for women, respectively. The mean daily intakes of total food and energy were 1219.1 g and 1740.9 kcal for men and 1071.3 g and 1432.6 kcal for women. The mineral intakes of men and women were 448.5 mg and 400.4 mg for calcium,955.3 mg and 803.7 mg for phosphorus, 13.3 mg and 11.1 mg for iron, 4302.8 mg and 3393.3 mg for sodium,2588.0 mg and 2264.9 mg for potassium, and 8.9 mg and 7.3 mg for zinc. The daily intakes of energy, calcium, zinc, vitamin $B_{2}$, and vitamin I were $76.1\%$, $60.1\%$, $73.1\%$, $68.6\%$, and $80.4\%$ of RDAs, respectively. The intakes of energy, calcium, zinc, vitamin $B_{2}$ and I were not meet Korean RDAs. Especially, calcium, zinc, and vitamin $B_{2}$ were less than $75\%$ of RDAs. Blood pressure of the subjects was 128.3/75.5 mmHg for men and 124.1/73.7 mmHg for women. Serum lipids of men and women were 180.2 mg/dL and 184.9 mg/dL for total cholesterol, 160.8 mg/dL and 137.6 mg/dL for triglyceride,41.5 mg/dL and 44.7 mg/dL for HDL-cholesterol,106.6 mg/dL and 112.7 mg/dL for LDL-cholesterol, and 3.5 and 3.3 for atherogenic index. While serum triglyceride and AI of men was significantly higher, HDL-cholesterol was lower than those of women. In the relation among mineral intakes, blood pressure, and serum lipids, we found a significantly negative correlation of intakes of calcium, calcium/phosphorus, calcium density with systolic blood pressure. There were significantly negative correlation between intake of calcium/phosphorus and serum cholesterol, calcium density and serum cholesterol, sodium intake and serum HDL-cholesterol. Based on these results, we concluded that high intakes of calcium, calcium/phosphorus and low sodium intake were associated with favorable blood pressure and serum lipid profiles in adult men and women. (Korean J Nutrition 38(10): 827$\sim$835,2005)

동맥압 형태를 고려한 오실로메트릭 모델분석 (Analysis of Oscillometric Model based on Shape of Arterial Pressure)

  • 임성수;이경중
    • 대한의용생체공학회:의공학회지
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    • 제21권4호
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    • pp.411-417
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    • 2000
  • 본 연구에서는 시뮬레이션을 이용하여 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하고 수축기압과 이완기압을 검출할 수 있는 새로운 알고리즘을 제시하였다. 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하고 수축기압과 이완기압을 검출할 수 있는 새로운 알고리즘을 제시하였다. 동맥압 파형 형태에 대한 오실로메트릭 방법을 분석하기 위해 동맥압 파형 형태를 쉽게 가변할 수 있는 동맥압 모델을 만들었으며, 기존의 정적인 동맥 압력-용적 지수함수 모델을 이용하여 오실로메트릭 모델의 구현 및 컴퓨터 시뮬레이션을 수행하였다. 동맥압 파형 형태와 보편화된 혈압 검출 기준인 특성비율과의 상관관계 분석을 통하여 동맥압 파형 형태와 맥압의 영향 때문에 특성비율이 수축기압과 이완기압을 결정하는 유일한 기준이 될 수 없음을 밝혔으며, 동맥압 파형 형태와 오실레이션 파형 형태의 상관관계 분석을 통하여 오실레이션 파형으로부터 동맥압 파형 형태를 추정할 수 있는 방법을 제시하였다. 최대 크기 오실레이션 파형과 동맥압 파형의 관계로부터 맥압을 구할 수 있는 맥압 표를 구성하여 수축기압과 이완기압을 검출할 수 있는 혈압 검출 알고리즘을 제시하였으며 그 결과 수축압, 이완압, 평균압의 절대편차 평균값은 각각 1.62%, 2.40%, 2.20%를 얻었다. 결론적으로 제안된 알고리즘은 정확한 혈압검출을 위한 유용 가능성을 보였다.

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다층 신경회로망 기법을 이용한 하이드로포밍 공정의 성형압력곡선추정 (Multi-layered neural network-based pressure curve estimation for hydroforming)

  • 현봉섭;김재선;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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    • pp.607-612
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    • 1992
  • For hydroforming process, determination of back-up fluid pressure in chamber is one of the most essential tasks. In this paper, we present a back-up pressure estimation system which estimates the back-up pressure of hydroforming process utilizing a multi-layered neural network. The neural network learns the nonlinear relation ship between the back-up pressure and the geometric state variables of hydroforming process. The proposed method does not necessitate sophisticated analysis on hydroforming process but some geometric intuition. The experimental results show that the neural network well approximates the nonlinear relationship between the back-up pressure and the geometric state variables of hydroforming process, thus giving the good estimation of back-up pressure vs punch stroke curve.

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램젯 엔진의 압력파 섭동에 따른 흡입구 거동 특성 해석 (Characteristics of the inlet with pressure perturbation in the ramjet engine)

  • 신동신;강호철
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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    • pp.94-97
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    • 2003
  • 램젯 공기 흡입구에 연소실의 압력파 섭동이 미치는 영향에 대해 살펴보았다. 연소실의 압력파 섭동은 500Hz의 주파수를 가지며, 출구 배압의 20%의 진폭으로 가정하였다. 계산결과는 흡입구 내에서 섭동압력에 의한 수직충격파의 거동의 특성을 보여주었으며, 섭동압력과 목부분의 수직 충격파는 약180도의 위상차를 가지고 있었다. 이러한 해석 결과로부터 하류 섭동파와 흡입구 유입 유량의 상관관계를 살펴보았다. 충격파가 카울 앞으로 이동된 상태에서는 아임계상태가 되며, 설계유량보다 작아졌고, 매 주기 하류 섭동이 시작되는 시점에서 급격한 유량 감소를 볼 수 있었다.

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