• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.406-409
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• 1997

In this paper, the power spectral analysis and fractral dimension analysis of heart rate variability(HRV) were performed to evaluate effects of orthostatic stress with head-up tilt on autonomic nervous system(ANS) for 24 young and healthy subjects(age: $24{\pm}5yr$.). The ECG and respiration signals were recorded at the tilt angle of $0^{\circ},\;15^{\circ},\;30^{\circ},\;45^{\circ},\;70^{\circ}$ and $90^{\circ}$ successively for 5 minutes per each stage under the condition of frequency controlled respiration (0.25Hz). Heart rate(HR) gradually increased as the angle increased. Similarly, according to the increment of angle, normalized low frequency(LF) component(0.05-0.15Hz) gradually increased, whereas normalized high frequency(HF) component (0.20-0.30Hz) was reduced. From these results it is speculated that orthostatic stress, head-up tilt, results in the prevalence of sympathetic tone in autonomic balance with the increment of sympathetic tone and the decrement of parasympathetic tone, which seems to mean that autonomic nervous system plays a major role in compensating for disturbances of cardiovascular system due to it.

• 한국전문물리치료학회지
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• 제10권2호
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• pp.99-110
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• 2003

The purpose of this study was to analyze the effects of three different pelvic tilts on sit-to-stand ativities and to suggest a new therapeutic approach for movement reeducation in patients who have difficulty with sit-to-stand activities. The three different pelvic tilts were: (1) comfortable pelvic tilt sit-to-stand (CPT STS), (2) posterior pelvic tilt sit-to-stand (PPT STS) and (3) anterior pelvic tilt sit-to-stand (APT STS). To analyze the kinematic component of STS, a motion analysis system (Zebris) was applied to the ankle, knee, hip joint, and thigh-off area. Also, to determine the onset time of muscle contraction, surface electrodes were placed to the rectus femoris muscle (RF), the vastus lateralis muscle (VL), the biceps femoris muscle (BF), the tibialis anterior muscle (TA), the gastrocnemius muscle (GCM), and the soleus muscle (SOL). One-way repeated ANOVA was used for the statistical analysis. First, significant differences were found in kinematic variables for the hip, knee, ankle joint, and thigh-off among the three activities. Second, there was significant difference in muscle activation pattern in TA. VL. and BF among three activities. In conclusion, the findings of this study suggest the following evaluative and therapeutic approach for STS activity: (1) Changes in knee and ankle joints should be prioritized and recruitment order differences in VL and RF can be generated to accomplish abnormal STS activity. (2) APT STS can be introduced for movement efficiency and functional advantage when abnormal STS is treated.

• 대한통합의학회지
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• 제7권1호
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• pp.19-26
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• 2019

Purpose : The aim of this study was to investigate the effects of the abdominal draw-in (ADI) exercise on the onset times of the gluteus maximus (GM) and erector spinae (ES) as well as the pelvic anterior tilt angle during prone hip extension (PHE). Methods : A total of 24 female adults were divided into two groups: those with normal abdominal muscles (n=12) and those with weak abdominal muscles (WAM; n=12). Before the intervention, the onset times of the GM and ES along with the pelvic angle during PHE were measured. Subsequently, the participants conducted the ADI exercise for 10 minutes. After conducting the ADI exercise, the onset times and the pelvic angle were re-measured. Results : In the pre-intervention comparison between the two groups, the WAM group showed faster ES onset times and higher pelvic angle than the normal group (p<0.05). In the WAM group, the ES onset times were significantly delayed after the ADI exercise (p<0.05). In both groups, the pelvic angle was significantly decreased after the ADI exercise (p<0.05). The decrease in the pelvic angle was significantly greater in the WAM group than in the normal group (p<0.05). The GM onset time was found to be not significant in all comparisons (p>0.05). Conclusion : Therefore, it can be concluded that after performing the ADI exercise, the pelvic anterior tilt during PHE is decreased in normal women and those with WAM, especially in the WAM group, suggesting that the ADI exercise can reduce the compensatory pelvic anterior tilt more effectively by delaying the ES onset times.

• The Journal of Korean Physical Therapy
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• 제35권4호
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• pp.89-94
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• 2023

Purpose: This study investigates the impact of self-myofascial release using a foam roller on the quadriceps femoris for pelvic stability. We further compare the effects of a GRID surface Foam Roller (GFR), a Non-Vibration Foam Roller (NVFR), and a Vibration Foam Roller (VFR). Methods: Thirty healthy adults (15 males, 15 females) participated in this study and were randomly assigned to one of three conditions: GFR, NVFR, or VFR. Participants walked at self-selected speeds with an arm sling before and after foam roller stretching. The analyzed gait parameters included pelvic tilt, pelvic obliquity, and pelvic rotation. Results: In the NVFR and VFR groups, there was a Significant differences were obtained in the pelvic tilt between pre-test and post-test values (p<0.05) in the NVFR and VFR groups, but no significant difference was observed in the GFR group (p>0.05). Comparing the amount of change between the three groups exhibited a significant decrease in pelvic tilt in the NVFR and VFR groups compared to the GFR group (p<0.017). No significant differences were found in pelvic obliquity and pelvic rotation (p>0.05) in all groups. Conclusion: While walking, the use of a VFR for self-myofascial release results in pelvic alteration by reducing the anterior pelvic tilt. We propose that a foam roller can be utilized to enhance pelvic stability during gait.

• 한국전문물리치료학회지
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• 제13권3호
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• pp.41-48
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• 2006

This study investigated therapeutic effects of pelvic tilt exercise (PTE) on weight bearing and body sway during sit-to-stand (STS) on 18 hemiplegic patients who had visited the Hanyang University Seoul Hospital and Injae University Sanggyebek Hospital physiotherapy rooms. The study compared the patients with 18 normal adults. The subjects were sampled out from those who could get up independently, maintain a standing posture more than 10 seconds, understand the movements of this study and have no difficulty in performing the tasks. By executing STS in a natural way with habitual movements before and after PTE, the weight bearing was measured by using Mediance II. In order to compare the difference of weight distribution, weight bearing and body sway on affected and nonaffected sides during STS before and after PTE, the Wilcoxon Signed Ranks Test was used. The statistical significance level was based on p<.05. The results revealed that the difference of weight distribution in the hemiplegic group was significantly decreased (p<.05), whereas there was no significant difference in the healthy group (p>.05). Weight bearing loaded on the affected side was $42.53{\pm}7.65%$ and $44.20{\pm}6.32%$, respectively, in the hemiplegic group during STS before and after PTE. Weight bearing during STS after PTE is increased significantly, as compared with weight bearing before PTE (p<.05). Body sway in the hemiplegic group was significantly decreased (p<.05). As mentioned, PTE proved to be effective for improvement in weight bearing on the affected side during STS of hemiplegic patients.

• 대한물리의학회지
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• 제15권1호
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• pp.133-141
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• 2020

PURPOSE: This study examined the effects of active release technique on pain, Oswestry Disability Index, and pelvic asymmetry in chronic low back pain patients. METHODS: Thirty five outpatients diagnosed with chronic low back pain were enrolled in this study. The patients were divided randomly into an active release technique therapy group(experimental group; n=18) and myofascial release technique therapy group(control group; n=17). These groups performed their respective therapy for a 40-minute session occurring twice a week over six weeks. The Visual Analogue Scale(VAS) was used to measure the subjects' pain, and the Korean Oswestry Disability Index(KODI) was used to measure the subjects' dysfunction. To assess the patients' pelvic asymmetry, their pelvic tilt and pelvic rotation were measured using X-ray imaging. RESULTS: Both the experimental group and control group exhibited significant decreases in their VAS and KODI scores after the therapy(p<.05). The experimental group exhibited a significant decrease in their pelvic tilt and pelvic rotation after therapy(p<.05). A significant difference was observed between the experimental group and the control group (p<.05). CONCLUSION: These results suggest that active release technique is effective in decreasing the level of pain and dysfunction in chronic low back pain patients. In addition, the active release technique is considered to be more effective in improving the pelvic tilt and pelvic rotation than myofascial release technique. This can be an effective method for the non-pharmacological and non-surgical treatment of chronic low back pain.

• 대한통합의학회지
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• 제8권1호
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• pp.147-157
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• 2020

Purpose : The purpose of this study was to investigate the effects of active release technique and lumbar stabilization exercise on pelvic asymmetry, muscle activation and pain in chronic low back pain patients. Methods : The subjects were 37 outpatients diagnosed with chronic low back pain. The patients were randomly divided into an active release technique therapy group (ART; n=18), and lumbar stabilization exercise group (LSE; n=19). These groups performed their respective therapy for a 30-minute session occurring two times a week over six-weeks period. To assess the patients' pelvic asymmetry, their pelvic tilt, and pelvic rotation was measured using X-ray imaging. EMG was used to evaluate the muscle activity of the lumbar muscle. The visual analogue scale (VAS) were used to measure the subjects' pain. Results : Both ART group, and LSE group exhibited statistically significant differences in their subjects' VAS and muscle activation of lumbar muscle after the therapy (p<.05). In ART group exhibited statistically significant decreases in their subjects' pelvic tilt and pelvic rotation after therapy (p<.05). There was a significant difference between the ART group, and LSE group (p<.05). Conclusion : The results of this study suggest that active release technique and lumbar stabilization exercise are effective in decrease pain and increase muscle activation in chronic low back pain patient. In addition active release technique is considered to be more effective in improving pelvic tilt and pelvic rotation than lumbar stabilization exercise.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2006년도 한국우주과학회보 제15권2호
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• pp.48-48
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• 2006

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
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• pp.51.3-51
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• 1998

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.197-202
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• 1999

A mechanical face seal is a tribe-element intended to control the leakage of working fluid at the interface of a rotating shaft and its housing. The leakage of working fluid decreases as the seal surfaces get closer each other. But a very small seal clearance results in a drastic reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals the compromise between low leakage and acceptable life is important and presents a difficult design problem. And the gap geometry of seal clearance affects seal performance very much and becomes an important design variable. In this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed using the Galerkin Finite Element Method, which can be readily applied to various seal geometries. The film pressures of the sealing dam are analyzed, including the effects of the seal face coning and tilt. Then, opening forces, restoring moments, leakages, and dynamic coefficients are calculated.