• 마케팅과학연구
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• 제20권2호
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• pp.123-134
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• 2010

考虑到消费者和供应商的利益, 公司利用网络为媒介来沟通并向消费者销售产品. 这一趋势使得很多研究者和实践者都关注网上购物环境这一领域. 本文测试了网上消费者行为和具有不同快乐主义水平的网址的模型. 与以往的研究不同, 我们包括了所有三种情绪(激励, 快乐和支配)并将此运用到模型中. 本研究中, 我们假设网址的外观, 例如背景颜色, 音乐和字体在消费者最初接触到网址时均影响三种情绪(Mazaheri, Richard, and Laroche, 2011). 反之, 这些情绪会影响消费者对网址氛围的感知–网址信息量, 效率和娱乐性的感知. 这些假设与Zajonc (1980)的研究一致. 他认为情感的作用是独立于感性的和认知操作并且可以影响回应. 我们因此提出网址氛围和流量的感知影响消费者对网址和产品的态度, 网址卷入和购买意图. 另外, 我们研究网址的快乐主义水平对模型中所有关系的调节作用. 因此, 我们比较享乐网址路径系数 "高" 和 "低". 我们用39个真实的网站涵盖了12种产品类别(8种服务和4种实物产品)来测试模型. 这其中, 回复者认为20个是高享乐, 19个为低享乐. EQS6.1的结果支持整体模型: x2=1787 (df=504), CFI=.994; RMSEA=.031. 所有假设都是显著的. 另外, 多群组分析表明在高享乐和低享乐网址群组之间的几个非不变量结构路径. 这些结果支持三种情绪影响消费者对网址氛围, 流量和其他消费者行为变量的认知. 我们发现快乐极大的影响这网址态度和网址娱乐性的认知. 激励积极的影响其他两种情绪, 网址信息量的认知和网址卷入. 而且, 激励对流量的影响非常显著. 这些结果说明在支配和消费者对网址效率的认知之间有很强的相关. 支配同时和网址态度和流量相关. 另外, 结果还表明网址卷入和对产品的态度是购买意图最重要的两个因素. 网址信息量和流量也积极的影响购买意图. 多群组分析的结果支持网址快乐主义的调节作用. 与低(高)享乐网址相比, 实用(享乐)属性对其他变量的影响比高(低)享乐网址更强. 在这三种情绪中, 支配(控制感)影响在高享乐网址中更强. 快乐影响在低享乐网址中更强. 而且, 网址信息量的影响对高享乐网址更强. 另一方面, 信息效率对网址信息量认知的影响和网址卷入对产品态度的影响在低享乐网址中更强.

• 신재생에너지
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• 제20권1호
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• pp.116-125
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• 2024

Ultra-low-head is an unexplored classification among the sites in which hydroelectric power can be produced. This is typically owing to the low power output and the economic value of the turbines available in this segment. A turbine capable of operating in an ultra-low-head condition without the need of a dam to produce electricity is developed in this study. A gate structure installed at a shallow water channel acting as a weir generates artificial head for the turbine mounted on the gate to produce power. The turbine and generator are designed to be compact and submersible for an efficient and silent operation. The gate angle is adjustable to operate the turbine at varying flow rates. The turbine is designed and tested using computational fluid dynamics tools prior to manufacturing and experimental studies. A parametric study of the runner blade parameters is conducted to obtain the most efficient blade design with minimal hydraulic losses. These parameters include the runner stagger and runner leading edge flow angles. The selected runner design showed improved hydraulic characteristics of the turbine to operate in an ultra-low-head site with minimal losses.

• International Journal of Fluid Machinery and Systems
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• 제3권2호
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• pp.129-136
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• 2010

The attachment of inducer upstream of main impeller is an effective method to improve the suction performance of turbopump. However, various types of cavitation instabilities are known to occur even at the designed flow rate as well as in the partial flow rate region. The cavitation surge occurring at partial flow rates is known to be strongly associated with the inlet back flow. In the present study, in order to understand the detailed structure of internal flow of inducer, we firstly carried out the experimental and numerical studies of non-cavitating flow, focusing on the flow field near the inlet throat section and inside the blade passage of a two bladed inducer at a partial flow rate. The steady flow simulation with cavitation model was also made to investigate the difference of flow field between in the cavitating and no-cavitating conditions.

• 대한기계학회논문집B
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• 제28권2호
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• pp.199-206
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• 2004

The heat transfer enhancement by pulsating flow in a plate heat exchanger has been experimentally investigated in this study. The effect of the pulsating flow, such as pulsating frequency and flow rate on the heat transfer as well as pressure drop in a plate heat exchanger has been studied in detail. Reynolds number in cold side of a plate heat exchanger is varied 100∼530 while that of hot side is fixed at 620. The pulsating frequency is considered in the range of 5∼30 Hz. The results of the pulsating flow are also compared with those of steady flow. It is found that the average heat transfer rate as well as pressure drop is increased as flow rate is increased for both steady flow and pulsating flow cases. When pulsating flow is applied to the plate heat exchanger, heat transfer could be substantially increased in particular ranges of pulsating frequency or Strouhal number; St=0.36∼0.60 and pressure drop is also increased, compared with those of steady flow. However, in the region of low pulsating frequency or high pulsating frequency, heat transfer enhancement is in meager. Heat transfer enhancement map is suggested based on Strouhal number and Reynolds number of pulsating flow.

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.193-197
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• 2005

Shunt valves used to treat patients with hydrocephalus were tested to investigate influence of intracranial pressure pulsation on their flow control characteristics. Five commercial shunt valves were tested in the flow loop that simulates pulsed flow under pressure pulsation. As 20cc/hr of flow rate was adjusted at a constant pressure, application of $40mmH_2O$ of pressure pulse increased the flow rate by $67.9\%.$ As a 90cm length catheter was connected to the valve outlet, increase in the flow rate was substantially reduced to $17.5\%.$ As the flow rate was adjusted to 40cc/hr at a constant pressure, increase in the flow rate was $51.1\%$ with the same pressure pulsation of $40mmH_2O$. The results indicated that pressure-flow control characteristics of shunt valves implanted above human brain ventricle is quite different from those obtained by syringe pump test at constant pressures right after manufacture. The influence of pressure pulsation was observed to be more significant at low flow rate and the flexibility of the outlet silicone catheter was estimated to significantly reduce flow increase due to pressure pulsation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.975-985
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• 2011

Cu-Matrix sintered brake pads and low alloyed heat resistance steel are most applied to basic brake system for high energy moving machine. In this research, we analyzed tribological characteristics for influence of air velocity between disk and pad. At low brake pressure with air flow, friction stability was decreased due to no formation of tribofilm at disk surface. But there are no significant change of friction coefficient at all test conditions. Wear rate of friction materials were decreased with increasing of air flow velocity. In result, air flow velocity influenced friction stability, wear rate of friction materials and disk but not friction coefficient.

• 대한기계학회논문집B
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• 제24권1호
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• pp.1-8
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• 2000

A modified low-Reynolds-number Reynolds stress model is developed for the calculation of drag-reducing turbulent flows induced by polymer injection. The results without polymer injection are compared with the results of direct numerical simulation to ensure the validity of the basic model. In case of drag reduction, profiles of mean velocity and Reynolds stress components, in two-dimensional channel flow, obtained with a proper value of viscosity ratio are presented and discussed. Computed mean velocity profile is in very good agreement with experimental data. And, the qualitative behavior of Reynolds stress components with the viscosity ratio is also reasonable.

• 한국환경과학회지
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• 제11권6호
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• pp.543-551
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• 2002

A Numerical simulation on the thermal flow performance was carried out to propose the incinerator type for the domestic refuses and to investigate the design factor and operating conditions. The SSTI(Standard Stoker Type Incinerator) proposed in this study was modified from the type with central f)ow. It has the characteristics of good mixing between refuse and hot combustion gas in primary combustion chamber and between unburned gas inflowing and secondary air jet in secondary chamber. By predictive results, the SSTI was no recirculation zone in secondary chamber so that mixing time was increased with high residence time. It has good characteristics of combustion and low emission. Parametric screening studies have been understood with phenomenon of combustion in incinerator.

• International Journal of Fluid Machinery and Systems
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• 제6권3호
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• pp.144-151
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• 2013

In this paper, the design method of a low-head propeller-type hydro turbine is studied for various numbers of blades on an axial propeller. We also investigate the relationship between geometrical parameters and internal performance parameters, such as angular velocities (100, 200, 300, 400 rpm) and 2.5~4m low heads through a three-dimensional numerical method with the SST turbulent model. The numerical results showed that the blade number had a more dominant influence than the change in heads and rotational speed on the flow characteristics of the turbine. The distributions of pressure and velocity in the streamwise direction of the propeller turbine were graphically depicted. Especially, the relationship among dimensionless parameters like specific speed ($N_s$), flow coefficient (${\phi}$) and power coefficient (P) were investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.608-609
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• 2008

An alternator which converts mechanical rotating energy into electric energy is an important component of a vehicle. It operates in broad range from 3000 RPM to 18000 RPM. So, sufficient flow rate and low noise are needed in such broad operating range for a cooling fan of this alternator. In current study, the cooling fan of an alternator is developed through DFSS process and numerical analysis. In order to calculate flow rate and noise level, SC/Tetra and FlowNoise S/W are used respectively, for a new developed fan, compared with original model, numerical result shows 3 dBA reduction and measured value shows 4 dBA reduction.