• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7B
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• pp.481-488
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• 2005

As the demand on the multimedia application increases, the congestion control algorithm for the multimedia applications becomes an important research issue. The ultimate goal of congestion control is to adapt the trans-mission rate at the sender to the mont of network resource available on the forward path. In general, the congestion control algorithms use the round trip time(RTT) to estimate the network congestion on the forward path. however, since the RTT includes the delay on both forward and backward paths, it is possible for the algorithms using the RTT to make a wrong decision such as deciding the congestion on the forward path due to the congestion built on the backward path. In this paper, we enhance the performance of RRC-OTT(Receiver-based rate control with one-way Trip Time) algorithm, which uses the one-way trip time(OTT) to estimate the network congestion. By separating the estimation mechanism on the forward path from the backward path, the performance of RRC-OTT algorithm is hardly affected by the congestion built on the backward path.

• Physical Therapy Rehabilitation Science
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• v.8 no.2
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• pp.61-66
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• 2019

Objective: The purpose of this study was to investigate the effects of resistance applied in various directions on lower extremity muscle activity and balance during squat exercise performance. Design: Cross-sectional study. Methods: Forty-one adults (19 males and 22 females) agreed to the study purpose and procedures. All subjects randomly performed squat exercises with an intensity of overcoming 10% of body weight resistance pulled forward, backward and general squats with $60^{\circ}$ of knee joint flexion. Electromyography was used to measure muscle activity of the vastus medialis oblique (VMO), rectus femoris (RF), vastus lateralis oblique (VLO), biceps femoris (BF), and semitendinosus (ST) muscles. The Wii Balance Board was used to assess balance during the three-method squat operation. Each operation was measured three times for 10 seconds. Results: There were significant differences in muscle activities of the VMO, RF, VLO, ST and balance ability with the application of three directions of resistance (p<0.05). Post hoc comparisons revealed that squats performed with resistance pulled in the backward direction resulted in higher VMO, RF and VLO activity than with the resistance placed in a pulled forward direction (p<0.05). In the ST, resistance applied in the pulled forward direction showed greater muscle activity compared to the pulled backward direction (p<0.05). With balance, squats performed with resistance pulled in the forward direction showed greater muscle activity than with resistance applied in the pulled backward direction and during general squat performance (p<0.05). Conclusions: In this study, squat exercises performed with resistance applied in the direction of pulling backwards was found to be the most effective in improving quadriceps muscle strength and balance. It is effective to provide resistance that is placed in the forward when it is difficult to perform a general squat due to weakness of the quadriceps.

• ETRI Journal
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• v.27 no.2
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• pp.206-218
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• 2005

We measure and compare externalities of IT and R&D capital stocks in different Korean industry sectors using inter-industry input-output tables of 1985, 1990, 1995 and 2000. We also compute the multiplier effects that relate to the directions of future economic effects. The key findings are as follows. First, we observed continuous capital deepening in all nine industries over the period of 1985 to 2000. Second, the backward multipliers of IT capital were the highest in the manufacturing industry. As for inter-industry externalities, the indirect backward multipliers, which exclude intra-industry backward multiplier effects within the industry, were also the highest in the manufacturing industry. Third, the forward multiplier effects of IT capital stock were the most substantial in the construction industry during the 1980s and in the manufacturing industry thereafter. Finally, using the transition multiplier matrix reflecting the backward effects of the two capitals in the past, the economic backward effects, especially the external economic effects, are predicted to increase through 2010 among all industries. The above findings suggest that, in order to maximize the forward and backward effects of the ever-increasing IT capital, we need to formulate an industry policy reducing the cost of capital accumulation in the manufacturing industry through improvement in productivity of the IT industry.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.164-171
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• 1999

An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• The Journal of Korean Physical Therapy
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• v.24 no.1
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• pp.29-34
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• 2012

Purpose: The purpose of this study was to evaluate the difference between respiratory function and speech production, according to the seat surface inclination while in the sitting position. Methods: Respiratory function (FVC, FEV1) and speech production (inspiratory frequency, unit reading time, paragraph reading time) were measured in 3 sitting conditions: horizontal seat surface, seat surface tilted forward 15 degrees, and seat surface tilted backward 15 degrees. Results: We found that the mean values of FVC and FEV1 were statistically significant different according to three types of sitting positions (p<0.05). The following result was observed: forward tilted sitting > horizontal sitting > backward tilted sitting. There was no significant difference in speech production between the different positions. Respiratory function and speech production had a significantly negative correlation in the forward tilted condition and the backward tilted condition. Conclusion: This finding suggests that the seat surface inclination have an effect on respiratory function. Especially, forward tilted sitting may be an effective posture that may help increases the respiratory function.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.16 no.2
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• pp.76-81
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• 2010

Purpose: This study examined how the degrees of muscle activity of Rectus Femoris and Tibialis Anterior during the four phases of walking vary according to three different treadmill slopes of $0^0$, $7^0$, and $15^0$. Methods: Subjects were 14 randomly selected healthy students attending G University in Seoul, Korea who had never had articular problems with lower limb and had no difficulties walking at the time of study. Results: 1) With respect to Rectus Femoris, in every phase of both forward and backward walking, there were significant differences among all of the slope degrees (p <.05), while the activity increased with increased slope degrees in every phase of backward walking. 2) For Tibialis Anterior, only in P2 and P3 of both forward and backward walking there were significant differences in every slope (p <.05). Conclusion: Both Rectus Femoris and Tibialis Anterior were found to be more active during backward walking compared to backward walking. In addition, the activity degree of Rectus Femoris was high between the early part of two foot support phase and the early part of one foot support phase, whereas that of Tibialis Anterior was high between the early part of one foot support phase and the latter part of both foot support phase.

• Physical Therapy Korea
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• v.23 no.3
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• pp.1-10
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• 2016

Background: Gait problems appear in most stroke patients. Commonly, stroke patients show the typical abnormal gait patterns, such as circumduction, genu recurvatum, and spastic paretic stiff-legged gait. An inclined treadmill gait exercise is good for gait problems of stroke patients. In addition, the backward walking training has been recommended in order to improve the component of the movement for the forward walking. Objects: The purpose of this study to investigated the effects of backward walking with inclined treadmill training on the gait in chronic stroke patients. Methods: A total of 30 volunteers were randomly allocated to two groups that walked on an inclined treadmill: the experimental group ($n_1=15$), which walked backward, and the control group ($n_2=15$), which walked forward. To measure the improvement of the patients' gait, a Figure of Eight Walking Test (F8W), Four Square Step Test (FSST), and Functional Gait Assessment (FGA) were performed. We also measured spatio-temporal gait variables, including gait speed, cadence, stride length, and single limb support using a three-axial wireless accelerometer. The measurements were taken before and after the experiment. The Wilcoxon signed-rank test was used to compare both groups before and after the interventions. The Mann-Whitney U test was used for the comparisons after the interventions. The statistical significance was set at ${\alpha}=.05$. Results: Before and after experiment, all dependent variables were significantly different between the two groups (p<.05). As compared to the control group, the experimental group showed more significant improvements in F8W, FSST, speed, cadence, stride length, and single limb support (p<.05); however, FGA in this group was not significantly different from the control (p>.05). Conclusion: Our results suggest that backward walking on an inclined treadmill is more effective for improving the gait of stroke patients than forward walking.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7285-7292
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• 2015

The purpose of this study was to investigate possibility of a forward gait with backward mechanism(dance gait) as rehabilitation and/or walking exercise by means of biomechanical variables. Thirteen professional women dancers(age, $21.1{\pm}1.3yrs$; height, $159.3{\pm}7.2cm$; body mass, $45.1{\pm}8.4kg$)participated in this study. We found that speed, stride length and double limb support time of a dance gait were more greater than backward gait, but stride width of dance gait less than a backward gait. Maximum RoMs, moments and powers of the lower limb joints on a dance gait were more frequent than a backward dance. These results were judged to be sufficient by the possibility of dance gait as rehabilitation and walking exercise.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.3
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• pp.83-91
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• 2024

Purpose : This case study aimed to investigate the effects of backward walking exercises with a front-loaded bag on craniovertebral angle (CVA), craniorotational angle (CRA), and gait variables in subjects with forward head posture (FHP). Methods : Two individuals in their twenties with FHP performed backward walking exercises on a treadmill while carrying a front-loaded bag with a load equivalent to 20 % of their body weight, for 30 minutes per day, three times a week, over two weeks. CVA and CRA were measured before and after the intervention using side view photographs taken from 1.5 meters away. CVA was calculated by marking C7, the tragus of the ear, and the outer canthus of the eye, and CRA was determined using the same landmarks. Image J software was used for angle analysis, with measurements taken three times and averaged. Gait variables such as step length and cadence were recorded using a step analysis treadmill and analyzed with the software included with the equipment, with measurements taken at baseline and after the two-week intervention. Results : Both participants demonstrated notable improvements in the CVA, indicating enhanced head alignment relative to the cervical spine. There was also a marked decrease in the CRA, suggesting a reduction in rotational misalignment. Although differences were observed in gait variables, such as step length and cadence, these changes were not consistent across measurements. The results suggest that backward walking exercises with a load carried in front can positively influence postural adjustments by aligning the cervical spine in individuals with FHP. Conclusion : The findings of this case study indicate that backward walking exercises with a front-loaded bag can effectively improve cervical spine alignment in individuals with FHP. Differences were observed in gait variables, such as step length and cadence, but these changes were not consistent across measurements. Future studies should explore these effects more comprehensively and consider optimizing the exercise protocol for better therapeutic outcomes.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.221-224
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• 1998

간섭신호가 원하는 신호에 coherent한 경우에는 원하는 신호와 간섭신호간의 cross correlation에 의해 공분산 행렬의 rank가 줄어들게 되어 coherent한 간섭신호의 도래각을 추정할 수 없게 된다. 이러한 문제를 해결하기 위해 발표된 기존의 방법중 대칭 어레이(Symmetric array)방법은 계산량이 많아지고 공간 스무딩(Spatial Smoothing)방법은 array aperture size에서 손해를 보게 되어 분해능이 떨어지는 단점이 있다[1,2,3].