• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.185-195
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• 2023

Objective: The purpose of this study is to improve TPI OnBaseU Power Test and golf performance by conducting CrossFit power training. Method: Three male golf players from University B participated in this study. They had 3 to 4 years of golf experience and participated in 8 weeks of CrossFit power training. Results: OnBaseU Power Test: There was a lot of improvement in Sit up throw (27.9%) and Chest pass (10.58%), but there was not much improvement in Baseline Toss (R5.9, L9.8%) and Vertical Jump (4.1%). Golf shot data: There was a very statistically significant difference in Club speed, Ball speed, and Total Length, which are related to speed, and there was no difference in Club path and Smash factor, which are related to accuracy and posture. Conclusion: CrossFit power training was effective in improving TPI OnBaseU Power Test and golf performance (Club speed, Ball speed, Total Length).

• Fashion & Textile Research Journal
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• v.1 no.2
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• pp.166-172
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• 1999

An experimental investigation has done for studying the changes of physical properties of the air-jet textured polyester yarn. Through the experiments of polyester 85/72 drawn yarn and 50/36 partially oriented yarn doubling' the following results are obtained. The tenacity of textured yarn decreased as the number of tension rings increased when the nozzle diameter was 1.2 mm. In the case when the tension ring was not used during the texturing process, the tenacity of textured yarn decreased as the nozzle diameter increased. But this tendency changed according to the number of tension rings used, the diameter of the nozzle, and yarn take-up speed. Breaking elongation decreased as the number of tension rings increased from one to four and the take-up speed increased at diameter 1.2 mm of the nozzle. The higher the diameter of the the nozzle the higher the breaking elongation until 1.4 mm. The number of interlacing went down as the diameter of the nozzle increased and the take-up speed of the yarn increased. The higher the number of tension rings, the lower the number of interlacing.

• Wind and Structures
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• v.9 no.1
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• pp.37-58
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• 2006

The paper describes a study about effects of upstream hills on design wind loads using two mathematical approaches: Computational Fluid Dynamics (CFD) and Artificial Neural Network (NN for short). For this purpose CFD and NN tools have been developed using an object-oriented approach and C++ programming language. The CFD tool consists of solving the Reynolds time-averaged Navier-Stokes equations and $k-{\varepsilon}$ turbulence model using body-fitted nearly-orthogonal coordinate system. Subsequently, design wind load parameters such as speed-up ratio values have been generated for a wide spectrum of two-dimensional hill geometries that includes isolated and multiple steep and shallow hills. Ground roughness effect has also been considered. Such CFD solutions, however, normally require among other things ample computational time, background knowledge and high-capacity hardware. To assist the enduser, an easier, faster and more inexpensive NN model trained with the CFD-generated data is proposed in this paper. Prior to using the CFD data for training purposes, extensive validation work has been carried out by comparing with boundary layer wind tunnel (BLWT) data. The CFD trained NN (CFD-NN) has produced speed-up ratio values for cases such as multiple hills that are not covered by wind design standards such as the Commentaries of the National Building Code of Canada (1995). The CFD-NN results compare well with BLWT data available in literature and the proposed approach requires fewer resources compared to running BLWT experiments.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.84-89
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• 2008

It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1069-1076
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• 2002

Contamination particles in a hard disk drive can cause serious problems including slider crash and thermal asperities. A recirculation filter is typically installed in the hard disk drive to remove the particles. Measurements and theoretical predictions of particle concentration decay with the filter are carried out for a commercially available HDD. Especially, the effect of disk rotational speed on the particle capture efficiency is investigated. Results show that filter efficiency is higher for higher disk rotational speed.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.3
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• pp.413-420
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• 2010

Purpose : The purpose of this study was to demonstrate the effect of trunk stability exercise on various support base and posture on gait speed, static and dynamic balance performance. Methods : Included 17 persons with stroke who were living in the community. Trunk stability exercise program was conducted three times per week, 50 minutes per session, for 8 consecutive weeks. Subjects were tested with 10 m walking test(sec), multidirectional reach test (cm), timed get up and go test(sec) and K.A.T.3000 at both (pre and post treatment) time points. Paired t-test was used to exam mean differences between pre and post treatment by using SPSS 12.0. Results : After 8 weeks exercise program, there were significant differences in gait speed, static and dynamic balance performance(p<0.05). Conclusion : This study have shown that trunk stability exercise on various support base and posture improve physical functions(gait speed, static and dynamic balance performance).

• Journal of the Korean Society of Safety
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• v.7 no.4
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• pp.13-21
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• 1992

The purpose of this reserch is to suggest grinding temperature for high effect grinding and to clarify the sufficient grinding heat by experiment and theory(developed finite element program). Main results to be obtained are as follows : 1) The grinding temperature distribution by F. E. M is comparatively in good apreement with the experimental results. 2) The up cut grinding method of grinding methods is decreased burning effect. 3) Regardless of the table speed on the temperature distribution in grinding surface layer, cooling effect is about 6-8times when developed nozzle is used.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.109-114
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• 2008

An improvement of vehicle fuel economy is one of the most important topic in automotive engineering. Lots of engineers make efforts to achieve 1% of fuel economy improvement. Engine friction is an important factor influencing vehicle fuel economy. This paper focuses on effect of engine friction on vehicle fuel economy during warm-up. A computer simulation is one of the powerful tools in automotive engineering field. Recently Simulation is attempting to virtual experiment not using expensive instruments. It is possible to presuppose fuel economy by changing the characteristic of accessories using CRUISE(vehicle simulation software). In this paper, fuel consumption at each part of the vehicle is analyzed by both of experiment and simulation. The results of fuel economy analysis on experiment substitute for Cruise to calculate fuel economy. The simulation data such as engine speed, brake torque, shift pattern, vehicle speed, fuel consumption level is well correlated to experiment data. In this paper, the change of warm-up time, faster or slower, through simulation is performed. As a result of the fast warm-up, fuel economy is improved up to 1.7%.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.35-39
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• 2009

The fouling around the surface of hull and propeller caused by marine organism and sea water occur in the vessel which is taken up mooring in a quay for a quite long time. Moreover, those are able to give rise to the loss of speed performance. The purpose of underwater cleaning is to improve the performance of vessel and customer satisfaction through management for fouling condition of propeller and hull. Therefore, systematic approach in connection with underwater cleaning is required so as to obtain the stable speed performance. As a result, we evaluate the effect of propeller polishing to speed performance from the case of 115K COT and 4,250 TEU Container Ship. In addition, we issue the importance of underwater cleaning through comparison of speed results depending on conditions of hull surface painted by silicon.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.47-56
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• 1999

New rolling speed prediction model has been developed for the precise presetting rolling speed of each finishing mill stand in the tandem hot strip mill. Those factors such as neutral point, work roll diameter, rolling torque, friction coefficient, bite angle and the thickness at each side of entry and deliver of the rolls were taken into account. To consider width effect on forward slip, calibration factors obtained from rolling torque has been added to new prediction model and refining method has also been developed to reduce the speed unbalance between adjacent stands. The application of the new model showed a good agreement in rolling speeds between the predictions and the actual measurements, and the standard deviation of prediction error has also been significantly reduced.