• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.241-250
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• 2022

Purpose : The purpose of this study was to investigate the effect of backward walking exercise on changes in the cervical angle and gait parameters in subjects with moderate forward head posture. Methods : Four subjects were selected for this study. In particular, subjects with an average of 43 subjects with moderate craniovertebral angles were selected as the criteria for subject selection. The exercise program consisted of a 5 minutes warm-up exercise, 20 minutes main exercise, and 5 minutes cool-down exercise. In the main exercise, the treadmill speed was 2.5 km/h for men, 2.0 km/h for women in the first week, from the 2nd week to the 4th week, it was increased by 0.5 km/h every week. Results : Craniovertebral angle increased by 2.06±2.46 ° before and after the backward walking exercise, and craniorotational angle decreased by -1.69±3.33 ° before and after exercise. As for the gait parameters, in the amount of change before and after the backward walking exercise, the left foot pressure was 4.58±5.70 % from front to back and the right foot pressure was 5.08±3.06 % from front to back. The left step length and right step length showed a change of -.33±4.43 cm and -2.08±7.26 cm, respectively. stride length showed a change of -2.59±11.18 cm. The left and right stance phase showed a change of -1.02±2.03 % and -1.23±1.54 %, respectively. The left and right swing phase showed changes of 1.02±2.03 % and 1.22±1.53 %, respectively. The left and right step times were -.01±.06 sec and -.02±.12 sec, respectively. The stride time showed a change of -.03±.18 sec. Conclusion : Changes in cervical angle and gait parameters were confirmed by performing backward walking exercise for subjects with moderate forward head posture for 4 weeks. Therefore, additional research should be conducted based on this case study.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.129-135
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• 2008

This research was examined the effect of Backward Walk on ground reaction force and we achieved it by using ground reaction force machine during the Backward Walk activity with Latin and Rumba dance. We find that it was significant difference of vertical(Fz) ground reaction force of right foot in touchdown and toe-off and vertical(Fz), horizontal(Fx), front-rear(Fy) ground reaction force of left foot. There was not significant differences in vertical ground reaction force between superior athlete and unskilled athlete, but there was a significant difference in left foot. Through this, we know that the sports capability of left foot which has been developed through the training is better in superior athlete group. Therefore understanding of difference in ground reaction force and repeated training can help the unskilled athlete and beginner to accomplish the accurate movement.

• Journal of Korea Port Economic Association
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• v.21 no.4
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• pp.141-160
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• 2005

This paper estimate and analyze the economic effect of the port industries as well its production inducement coefficient, effect ratio and response ratio using above-mention input-output analysis. The results of analysis is that the production inducement effects and the forward and backward linkage effects of port industries sectors are evaluated low evaluations. This results is not the port industry doesn't have low effects and low contributions to Korea economy, port industries are more used in the field of export and import sectors than domestic demand and supply sectors. Accordingly, the import inducement coefficients of shipping industry is most high among the 404 detailed sectors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2051-2063
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• 1995

An improved version of nonlinear low-Reynolds-number k-.epsilon. model is developed. In this model, the limiting near-wall behavior and nonlinear Reynolds stress representations are incorporated. Emphasis is placed on the adoption of Ry(.iden. $k^{1}$2/y/.nu.) instead of $y^{[-10]}$ (.iden. $u_{{\tau}/y/{\nu}}$) in the low-Reynolds-number model for predicting turbulent separated and reattaching flows. The non-equilibrium effect is examined to describe recirculating flows away from the wall. The present model is validated by doing the benchmark problem of turbulent flow behind a backward-facing step. The predictions of the present model are cross-checked with the existing measurements and DNS data. The model performance is shown to be generally satisfactory.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.203-206
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• 2008

There are lots of the narrow pass on alluvial channel of Korea. Most of research about this narrow pass of channel were focused on incremental effect of water level at backwater segment. In the meantime this research showed that it is important to valuate the river-bed variation at backward and forward around narrow pass. The sediment deposit at not only the backward of narrow pass but also the forward affected incremental effect of water level. The sediment deposit at the forward of narrow pass headed by sediment that passed through the narrow passed or scoured right around it.

• Transactions of Materials Processing
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• v.18 no.8
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• pp.640-645
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• 2009

Recently, boss and rib test based on backward extrusion process was proposed to quantitatively evaluate the interfacial friction condition in bulk forming process. In this test, the tube-shaped punch with hole pressurizes the workpiece so that the boss and rib are formed along the hole and outer surface of the punch. It was experimentally and numerically revealed that the height of boss is higher than that of the rib under the severe friction condition. This work is focused on the effect of the punch design and flow stress on deformation pattern in boss and rib test. From the boss and rib test simulations, it was found that there is slight variation in both the heights of boss and rib according to the length of punch land, nose radius, and face angle. However the hole diameter of the punch and the clearance between the punch and die have a significant influence on the calibration curves showing the heights of the boss and rib. In addition, the effect of flow stress on the calibration curves was investigated through FE simulations. It was found that there is no effect of strength coefficient of the workpiece on the calibration curves for estimation of friction condition. On the other hand, the strain-hardening exponent of the workpiece has a significant influence on the calibration curve.

• Journal of Korea Port Economic Association
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• v.22 no.2
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• pp.35-60
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• 2006

This paper uses input-output techniques to analyze the impacts of the coastal and inland water transportation (CIWT) upon the Korean economy between 1990 and 2000. The impacts were identified by means of backward and forward linkages effects, production inducing and import-inducing effects, and commodity prices repercussion effects of the coastal and inland water transportation. The data of this study come from The Bank of Korea databases for Input-Output Structure of the Korean economy. The major findings in this study can, among others, be summarized: that the power of dispersion(=backward linkage effect) and the degree of sensitivity (=forward linkage effect) of CIWT are higher than those of the deep sea transportation sector and that it has higher production-inducing effect than the average of total industries, while it has lower import-inducing effect than the average of total industries.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.1-8
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• 2019

The synthetic turbulence generation model for inlet boundary conditions of subsonic Backward Facing Step (BFS) was investigated. The average u-velocity and Reynolds stress at inlet boundary follows experimental data. Synthetic Eddy Method (SEM), random noise, and uniform flow conditions were implemented relative to the synthetic turbulence generation method. A three dimensional Large Eddy Simulation (LES) was applied for turbulent flow simulation. Turbulent and mean flow characteristics such as flow reattachment length, velocity profiles, and Reynolds stress profiles of BFS were compared with respect to the turbulent effects.

• Advances in nano research
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• v.8 no.3
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• pp.245-254
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• 2020

This work examines the fundamental vibrational characteristics of a spinning CNT-based nano-rotor assuming a nonlocal elasticity Euler-Bernoulli beam theory. The rotary inertia, gyroscopic, and rotor mass unbalance effects are all taken into consideration in the beam model. Assuming a nonlocal theory, two coupled 6th-order partial differential equations governing the vibration of the rotating SWCNT are first derived. In order to acquire the natural frequencies and dynamic response of the nano-rotor system, the nonlinear equations of motion are numerically solved. The nano-rotor system frequency spectrum is shown to exhibit two distinct frequencies: one positive and one negative. The positive frequency is known as to represent the forward whirling mode, whereas the negative characterizes the backward mode. First, the results obtained within the framework of this numerical study are compared with few existing data (i.e., molecular dynamics) and showed an overall acceptable agreement. Then, a thorough and detailed parametric study is carried out to study the effect of several parameters on the nano-rotor frequencies such as: the nanotube radius, the input angular velocity and the small scale parameters. It is shown that the vibration characteristics of a spinning SWCNT are significantly influenced when these parameters are changed.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.