• 한국공작기계학회논문집
• /
• 제17권4호
• /
• pp.89-94
• /
• 2008

Differential pressure flow meters which have a shape of triangular separate bar(TSB) were tested for investigating the flow rate characteristics of the flow meters with varying the temperature of the gas flow. Three kinds of the triangular separate bar flow meters whose aerodynamic angles are different one another are used. The mass flow rate of the flow meters are evaluated using a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters, and atmospheric pressure. A burner system which is similar to gas turbine was used for raising the gas flow temperature. The burner system was operated with varying the air/fuel ratio by controlling both the fuel injection rate from the fuel nozzle and air flow rate from a blower. An empirical correlation between the mass flow rate at the TSB flow meter and the non-dimensional parameter was obtained. The empirical correlation showed linear relationship between the mass flow rate and the non-dimensional parameter H. Also, the mass flow rate characteristics at the TSB flow meter was affected by the gas temperature.

• 경영정보학연구
• /
• 제8권1호
• /
• pp.125-139
• /
• 2006

본 연구는 Csikszentmihalyi(1977)에 의해서 소개되고 Hoffman과 Novak(1996)에 의해서 확장된 플로우 개념을 수용하여 모바일 인터넷 서비스의 사용에 있어 Novak, Hoffman과 Yung(1997)이 이론화한 플로우(flow)개념을 도입하여 모바일 인터넷 환경요인들이 플로우 및 플로우 선행요인에 영향을 미치는지를 확인해 보고 기존 인터넷 환경에서와 같이 모바일 인터넷 환경에서도 플로우 이론이 성립되는가를 구조 방정식분석을 통해 검정해 보았다. 본 연구는 서비스 수용모델과 플로우 개념에 관한 문헌연구, 설문조사, 모바일 인터넷 플로우 모델의 제시, 그리고 가설검정으로 구성되며 그 결과는 다음과 같다. 첫째, 플로우 선행요인인 도전감에 영향을 미치는 요인은 인터넷 환경요인 중 매체 특성, 컨텐츠 특성, 모바일 인터넷 매체의 사용 편의와 정보전송 품질, 컨텐츠의 유일성, 적시성, 간결성으로 나타났다. 둘째, 플로우 선행요인인 숙련도에 영향을 미치는 요인은 컨텐츠특성, 요금특성, 사용특성이며 컨텐츠의 유일성, 적시성, 간결성, 그리고 요금청구의 명확성, 요금제선택의 다양성, 즉시 연결성이 숙련도에 영향을 미치는 것으로 나타났다. 플로우 선행변인인 도전감은 플로우에 정(+)의 유의한 영향을 미치는 것으로 나타났다. 이러한 결과는 소비자들의 모바일 인터넷 사용에 있어 도전적 태도가 플로우 경험에 영향을 미치며 도전감을 증가 시키는 모바일 인터넷 특성을 통해 통찰력 있는 시각을 제시해준다.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
• /
• pp.150-154
• /
• 2009

Flow distribution characteristics with varying inlet flow-rate in mega collector risers have been investigated, using commercial code FLUENT. The heat transfer in mega collector was not considered in this numerical study. Through the simulation, the following results were found. First, flow distribution characteristics in mega collector risers show the similar tendency in all cases. Secondly, with increased inlet flow-rate, flow distribution uniformity was getting worse.

• 보건행정학회지
• /
• 제3권2호
• /
• pp.27-80
• /
• 1993

It is widely known that patients' utilization pattern for medical care facilities and the patientflow are influenced by multi-factors, such as demographic characteristics, structural characteristics of society, socio-psychological characteristics(value, attitude, norms, culture, health behavior, etc.), economic characteristics(income, medical price, relative price, physician induced demand, etc.), geographical accessibility, systematic characteristics(health care delivery system, payment methods for physician fees, form of health care security, etc.), and characteristics of medical facilities(reliability, quality of medical care, convenience, kindness, tec.). This study was conducted to research the mechanism of patient-flow according to changes of health care system(implementation of national health insurance, health care referral system and regionalization of health care utilization, etc.) and characteristics of medical facilities(ownership of hospital, characteristics of medical services, non-medical characteristics, etc.). In this study, the fact could be ascertained that the patient-flow had been influenced by changes of health care system and characteristics of medical facilities.

• 전기학회논문지
• /
• 제58권7호
• /
• pp.1329-1335
• /
• 2009

This paper presents the flow characteristics in the fluid circulation loop using the tubular type linear induction motor(TLIM) electromagnetic pump. A TLIM pump was designed using the equivalent and genetic algorithm for the flow system of 40[1/min]. The flow characteristics are analyzed by coupling the Maxwell equations with the Navier-Stokes equation. The analysis algorithm also takes account of the effects of the thrust. The flow characteristics are analysed with the proposed method and compared with the commercial program and experiment and discussed.

• 한국자동차공학회논문집
• /
• 제23권1호
• /
• pp.139-147
• /
• 2015

This paper is the second investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous work, several assumptions used in the steady flow bench were examined and it was concluded that the assumption of the solid rotation might cause serious problems. In this study, intake valve angle is selected as a main parameter for the assessment because the main flow direction to cylinder governed by this angle has the strongest influence on the in-cylinder flow pattern. For this purpose, four heads, which have the different angle, are prepared and the flow characteristics are estimated both by the conventional impulse swirl meter and a particle image velocimetry at 1.75 times bore position apart from the cylinder head, which is widely used plane in the steady flow measurement. The results show that both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75 plane, however, the effects of two factors act in the opposite direction. In addition, the profile's influence is much greater than that of the eccentricity.

• 대한의용생체공학회:의공학회지
• /
• 제18권2호
• /
• pp.179-186
• /
• 1997

Steady and physiological flows of a Newtonian fluid and blood in the abdominal gorta/iliac artery bifurcation are numerically simulated to understand the etiology and pathogenesis of atherosclerosis. Distributions of velocity, pressure, and wall shear stress in the bifurcated arterial vessel model are calculated to investigate the differences of flow characteristics between steady and physiological flows and to compare flow characteristics of blood with that of a Newtonian fluid For the given Reynolds number the flow characteristics of physiological flows for a Newtonian fluid and blood in the bifurcated arterial vessel are quite different from thcse of steady flows. No flow separation or flow reversal in the bifurcated region appears downstream of a stenosis during the acceleration phase. However, during the deceleration phase the flow exhibits flow separation in the outer walls of daugtlter branches, which extends to the entire wall region.

• 한국분무공학회지
• /
• 제27권3호
• /
• pp.144-154
• /
• 2022

Gas injection is a technique applied to improve throttling in liquid rocket engines and atomization in effervescent injectors. When a gas is injected into a liquid, it creates a two-phase flow inside the injector. The changes (bubbly flow, slug flow, annular flow, etc.) in the two-phase flow affect the injector's spray characteristics. In this study, cold-flow tests were performed by using three injectors with different orifice diameters and four aerators with different gas injection hole diameters. The experiments were done by changing the thrust ratio (liquid mass flow rate ratio) and gas-liquid mass flow rate ratio. Two-phase flow transition, breakup length, and discharge coefficient according to the injector/aerator design and flow conditions were investigated in detail.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권1호
• /
• pp.110-118
• /
• 2008

It is essential for the valid design of a marine flow-control valve to exactly know its flow characteristics. The present study has numerically investigated the flow characteristics inside a marine throttle-type globe valve using a kind of commercial CFD code, CFX10.0, with an adoption of the SST (Shear-Stress Transport) turbulence model. To validate the numerical approach, the flow coefficients are compared with the experimental ones. Results show that the globe valve is effective in the control of flow rate according to the opening ratio in case of the forward-direction flow, whereas it is effective in the flow shutoff in case of the reverse-direction flow. Around the inlet of the valve, a recirculation region is formed due to the blunt body shape, the turbulence intensity becomes strengthened and then an abrupt pressure loss occurs.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.790-795
• /
• 2001

Since the characteristics of combustion and pollutant in Diesel engines were mainly affected by the characteristics of in-cylinder gas flow and fuel spray, an understanding of those was essential to the design of the D.I. Diesel engines. The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since the air resistances in intake and exhaust flow passages, valve lift and valve shape influence greatly to the volumetric efficiency, it is very important to investigate the flow characteristics of intake and exhaust port which develops air motion in the combustion chamber. This paper presents the results of an experimental investigation of steady flow through the various kinds of commercial cylinder head ports, and the development procedures of HHI's H21/32 prototype cylinder head ports.