• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.116-124
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• 2002

An experimental parametric study of a tubular heat exchanger has been carried out far the saturated water at atmospheric pressure to determine effects of tube inclination on pool boiling heat transfer. For the analysis, seven inclination angles(0°, 15°, 30°, 45°, 60°, 75°, and 90°) and two tube diameters(12.7 and 19.1 mm) were tested. According to the results, inclination angles result in very much change on pool boiling heat transfer. As the inclination angle is around horizontal or vertical, maximum or minimum heat transfer is expected, respectively. For the same wall superheat(about 5.5K) the ratio between two heat fluxes fur $\theta$ =15° and 75° has the value of more than five when the tube diameter is 12.7 mm and heat flux is increasing.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.135-144
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• 1998

High speed machining is a key issue in die and mold manufacturing recently. Even though this technology has great potential of high productivity. tool wear accelerated by high cutting speed to the hardened materials is other barrier. In this research, we attempted to reduce tool wear by considering tool inclination angle between tool and workpiece. The boundary lines describing machined sculptured surfaces were represented by both of cutting envelop condition and the geometric relationship of successive tool paths. Chip cross section, and cutting length could be obtained from the calculated cutting edge and the rotational engagement angle. From the simulation results, machining inclination angle of tool of $15^\circ$ was good enough from the point of tool wear and cutting force, and this value was verified through the cutting experiment of high speed ball end milling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.302-314
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• 1994

The effects of the inclination of enclosure and partition on natural convective flow and heat transfer were investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was positioned perpendicularly at the mid-height of one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were performed with the variations of the partition length and Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). The effects of the inclination angle of enclosure and partition on the heat transfer within an enclosure were also studied. As the results, the increase of the inclination angle of enclosure rapidly raised the heat transfer rate, while the inclination angle for the maximum Nusselt number was retarded with the increase of the partition length and the decrease of the heat transfer rate became larger in proportion to the increase of the partition length. The Nusselt number obtained by the inclination of partition was smaller than that of the inclination of enclosure. However, the difference of the heat transfer rates was considerably decreased at the longer partition lengths and the trends for the variation of the average Nusselt number were more similar with that of the inclination of enclosure. The upward oriented partition increases the convective heat transfer distinctly in contrast to that of the inclination of enclosure as the partition length increases.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.261-266
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• 2010

Human body is hard to be in perfect balance during walking. Most of time the trunk is supported by one leg and the center of mass(COM) falls to the contralateral side. Thus, dynamic variables such as the velocity of the COM should be considered when gait stability is evaluated. The purpose of this study was to investigate whether the extrapolated center of mass(XCom) which utilized the COM position and its velocity, is appropriate to evaluate gait stability. Ten healthy adults participated in this study and performed 3 different types of gaits(normal(NG), hands on waists(HWG), and hands on shoulders(HSG)) onto 4 different types of obstacle(obstacle height: 0%, 30%, 40% and 50% of leg length). Medio-lateral Com-CoP and XCom-CoP inclination angle were calculated during support phase. For all condition, greater M-L XCoM-CoP inclination angles were found(p<.05) compared with those of matched obstacle height CoM-CoP. Especially, M-L XCoM-CoP inclination angle at 50% height revealed the best condition for monitoring dynamic stability. Significantly increased in M-L XCoM-CoP inclination angle was found(p<.05) as obstacle height increased on NG and HWG.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.222-228
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• 2007

The effect of inclination angle on the heat transfer and pressure drop characteristics of brazed aluminum heat exchangers is experimentally investigated. Three samples having different fin pitches (1.25, 1.5 and 2.0 mm) were tested. Results show that heat transfer coefficient is not affected by the inclination angle. However, the friction factor increases as the inclination angle increases with negligible difference between the forward and backward inclination. Both the heat transfer coefficient and the friction factor are the smallest at $P_f$=1.5mm, followed by $P_f$=2.0mm and 1.25mm. Possible explanation is provided considering the louver layout. Comparison with existing correlations is also mad.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.29-35
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• 2006

Two-dimensional numerical simulation has been performed to investigate mixed convection heat transfer between inclined parallel plates with bottom-heated and top-cooled uniformly. The ratio of parallel plate length to height is 9.33, Prandtl number is 909(that of silicone oil at 298K) and Rayleigh number is 8600. In the ranges of the Reynolds number Re from 0 to 1.8 and the angle of inclination ${\theta}$ from 0 to 90 degree. The governing equations are discretized using the finite volume method. In this study, the effects of the Reynolds number, the angle of inclination, and the local and mean Nusselt numbers are presented and discussed. It is found that the periodic flow of mixed convection between inclined parallel plates is shown at $0^{\circ}{\leq}\;{\theta}<30^{\circ},\;Re<0.063$, and the flow pattern can be classified into three patterns which depend on Reynolds number and the angle of inclination. The minimum average Nusselt numbers occur at Re=0.05 regardless of the angle of inclination.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2296-2302
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• 2005

This study is focused on the comparison of heat transfer performance of two thermosyphons having 60 straight and helical internal grooves. Distilled water has been used as working fluid. Liquid fill charge ratio defined by the ratio of working fluid volume to total internal volume of thermosyphon, the inclination angle and operating temperature were used as experimental parameters. The heat flux and heat transfer coefficient are estimated from experimental results. The conclusions of this study may be summarized as follows; Liquid fill charge ratio, inclination angle and geometric shape of grooves were very important factors for the operation of thermosyphon. The optimum liquid fill charge ratio for the best heat flux were $30\%$. The heat transfer performance of helically grooved tube was higher than that of straight grooved tube in low inclination angle (less than $30^{\circ}$), but the results were opposite in high inclination angle (more than $30^{\circ}$). As far as optimum inclination angle concerns, range of $25^{\circ}\~30^{\circ}$ for a helically grooved tube and about $40^{\circ}$ for a straight grooved tube are suggested angles for the best results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.15-19
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• 1996

The cusp height in ball end milling, flat end milling and filleted end milling according to various surface inclination angle was calculated. The calculation result shows that, for each kind of tools, there exists certain range of inclination angle in which cusp height characteristics favorable. From machining time calculation, filleted end mill found to be superior to flat end mill in rough machining of sculptured surface.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.165-172
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• 1998

An experimental study on the heat transfer of the inclined thermosyphon with low integral-fins in which boiling and condensation occurred is performed to investigate its heat transfer performance. Water and CFC-30 have been used as the working fluids. The operating temperature and the inclination angle of thermosyphon have been used as the experimental parameters. The heat flux input and the inclination angle $\theta$ towards the vertical position were varied in steps. The heat transfer rate in the thermosyphon was depended upon the inclination angle. In addition, it is to obtain the overall heat transfer coefficients and the characteristics as a operating temperature for the practical applications.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.397-403
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• 2011

The purpose of this study is to analyze the immediate effects of five toed shoes on foot structure. Subjects consisted of 26 college-aged women with pes planus. X-ray analysis of student feet were performed both barefooted and with five toed shoes. Dependent variables were hallux valgus angle, calcaneal inclination angle, 1st metatarsal declination angle, and intermetartarsal angle. Independent t-test was used for statistical analysis along with SAS. Overall, there were statistically significant changes of test subject's dependent variables when wearing five toed shoes. Specifically, the hallux valgus angle decreased, the calcaneal inclination angle and 1st metatarsal inclination angle increased, and intermetatasal angles both increased and decreased, shifting towards normal range. In every case the dependent variables shifted towards a more normal range while subjects wore five toed shoes. This study only examined the immediate corrective effects of five toed shoes on foot structure, but long-term studies are needed to understand the prolonged effects of five toed shoes on foot structure.