• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.467-472
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• 2000

Most of the past experimental or analytical studies were performed for the curved bend with a square cross-section. Velocity profiles and Reynolds stresses of the turbulence flow in the 270 degree bend with circular cross-section were measured by a hot-wire anemometer. The mean velocity of primary flowing direction effected by the downstream of bend in the entry region of the bend. The flow in the inner part of the bend slowed the distribution velocity relatively large and unsymmetric phenomenon. In the strong secondary flow occurred when the flow passed in the region of 45 degree to 90 degree. The secondary flow appeared very large value in the neighbor region of inner wall.

• 대한기계학회논문집B
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• 제27권5호
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• pp.569-578
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• 2003

In the present steady the flow characteristics of turbulent steady flows were experimentally investigated in the exit region of join stream. The experimental was carry out to measure the velocity profiles of air in a square duct. For the measurement of velocity profiles, a hot-wire anemometer was used. The experimental results shows that the velocity profiles do not change behind the fully developed flow region , which is defined as dimensionless axial direction x/Dh=50. In addition, the gradient of shear stress distribution became stable as the flow reached progress downstream.

• 환경위생공학
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• 제17권1호
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• pp.28-35
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• 2002

본 연구 목적은 계측저항이 없는 열선유속계를 이용하여 매립지 가스의 유량을 산정할 때 가스조성에 의해 발생되는 계측오차를 최소화할 수 있는 방안을 제시하고자하였다. Rotor meter와 가스조성 밀도를 이용하여 산정한 관 중심유속을 계측저항이 없는 열선유속계를 이용하여 구한 관 중심유속을 비교함으로서 계측오차를 측정하였다. 실험결과 열선 유속계와 rotor meter를 이용한 매립지 가스유속 계측오차의 최소화 방안을 통하여 매립지 가스유량의 오차 범위를 10% 이내로 최소화 할 수 있는 것으로 조사되었다.

• 대한조선학회지
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• 제25권3호
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• pp.13-18
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• 1988

Three-dimensional turbulent flows over ship sterns are measured by using the hot-wire anemometer and static holes in the wind tunnel. A conventional stern and a barge-type stern are adopted for the present study. Three components of mean velocities, pressures on the hull and six components of Reynolds stresses are measured. Longitudinal velocity contours are more parallel to the hull surface and weak bilge vortices appear on the barges type stern rather than the conventional stern. Those viscous flow patterns may have close relations to improvements of the resistance and propulsion performance, which have been verified in the towing tests. Measured data files are valuable for the ensuing numerical studies.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.162-168
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• 2001

In the present study, flow visualizations, hot-wire velocity measurements and computational fluid dynamics were performed in order to determine complicated air flow characteristics in a neonate incubator. In this study, following conclusions can be made: (1) The flow visualization technique developed in the present study revealed an enough qualitative information for the flow field in the neonate incubator. Flow structures in a neonate incubator with a realistic three-dimensional shape was successfully visualized the present study. (2) Results from the flow visualization were relatively in good agreements with those obtained from the computational fluid dynamics. (3) Velocities very near the neonate measured by the hot-wire anemometer were relevant to those obtained from the computational fluid dynamics. (4) Temperatures were higher at the neck region and the medial aspect of both thighs, but lower in both extremities. (5) Small vortices between the neonate and the mattress might interfere with convective and evaporative heat transfers on the neonate's surface. In the fluid dynamic aspect, it is important to eliminate the formation of these small vortices for the design of incubator chamber.

• 동력기계공학회지
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• 제10권3호
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• pp.23-31
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• 2006

Mean velocities and turbulent characteristics in the three-dimensional flow fields of a gun-type gas burner were measured by using triple hot-wire probe (T-probe) in order to compare them with the results already presented by X-type hot-wire probe (X-probe). Vectors obtained by the measurement of two kinds of probes in the horizontal plane and in the cross section respectively show more or less difference in magnitude each other, but comparatively similar shape in overall distribution. Axial mean velocity component along the centerline shows that the value by T-probe is about ten times smaller than that by X-probe above the range of X/R=3. Also, the axial component of turbulent intensity along the centerline appears the biggest difference between the two probes. Moreover, axial mean velocity component, axial turbulent intensity component and rotational along the Y-directional distance show a big difference between slits and swirl vanes. On the whole, the values by T-probe appear smaller than those by X-probe.

• 대한기계학회논문집
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• 제5권4호
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• pp.320-328
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• 1981

Experimental study of a round. free air jet is accomplished using a crossed hot wire probe with a constant temperature hot wire anemometer. Mean velocity Profiles, Reynolds stresses, tubulent intensities, velocity probability densities and correlation functions are measured in the down tream region. These values are calculated and averaged inthe correlation and probability analyzer. The reults are interpreted by the output of te dual beam oscilloscope.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.31-34
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• 2003

The near wake behind a sinusoidal cylinder has been investigated quantitatively using hot-wire anemometer and qualitative. The mean velocity and turbulence intensity were measured in streamwise and spanwise direction. The results show that the wake in the saddle plane has a longer vortex formation region and rapid reversed flow than that in nodal plane. The elongated vortex formation region of sinusoidal cylinder is related with drag reduction. In addition, the flow visualized with particle tracing method support the flow characteristics of sinusoidal cylinder measured by hot-wire.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1299-1308
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• 2003

This paper is studied to investigate the effect of slits and swirl vanes on the development of turbulent flow fields in gun-type gas burner with a cone type baffle plate because this gas burner is generally composed of eight slits and swirl vanes. All of turbulent characteristics including mean velocities were measured in the horizontal plane and cross section by using X-type hot-wire probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 l/min in the test section of subsonic wind tunnel. Slits cause the fast jets, and then they have the characteristic that the flow is not adequately spread to radial direction and has long flow length and very small flow velocity distribution in the central part. On the contrary, swirl vanes does not have long enough for adequate flow length to downstream because the rotational flow diffuses remarkably to radial direction. However, the suitable arrangement between slits and swirl vanes causes effective flow width and flow length, and then it promotes fast flow mixing over the entire region including central part to increase turbulence more largely and effectively. Therefore, it is thought as a very desirable design method in gun-type gas burner to locate slits on the outside of swirl vanes.

• 동력기계공학회지
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• 제5권1호
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• pp.21-26
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• 2001

This paper represents the turbulent intensity, the turbulent kinetic energy and Reynolds shear stress in the X-Y plane of cone type swirl gas burner measured by using X-probe from the hot-wire anemometer system. The experiment is carried out at flowrate 350 and $450{\ell}/min$ respectively in the test section of subsonic wind tunnel. The turbulent intensity and the turbulent kinetic energy show that the maximum value is formed in the narrow slits distributed radially on the edge of a cone type swirl burner, hence, the combustion reaction is anticipated to occur actively near this region. And the turbulent intensities ${\upsilon}\;and\;{\omega}$ are disappeared faster than the turbulent intensity u due to the inclined flow velocity ejecting from the swirl vanes of a cone type baffle plate of burner. Moreover, the Reynolds shear stress $u{\upsilon}$ is distributed about three times as large as the Reynolds shear stress $u{\omega}$ in the outer region of the cone type gas burner.