• The Journal of Korean Physical Therapy
• /
• v.12 no.3
• /
• pp.339-347
• /
• 2000

To elucidate pressure pain threshold of pericranial muscle due to involuntary. the effect of 30 min or forward head position(FHP) was studied in 20 patients with episodic tension-type headache and in 20 control without headache. Pressure pain thresholds were recorded before and after the FHP. and evaluated by pressure algometry. Thresholds increased in the patients and control after FHP. Relation between thresholds in patients anf control before FHP were not significant differences, but thresholds increased in patients after FHP. So, involutary muscle contraction due to FHP may be effect pressure pain threshold or pericranial muscle.

• Journal of the Ergonomics Society of Korea
• /
• v.35 no.6
• /
• pp.503-517
• /
• 2016

Objective: The aim of this study was to evaluate the effectiveness of 3 dimensional contoured pillow through analyzing contact pressure and to suggest its design guidelines through analyzing the posture of head and neck area. Background: The quality of sleep is a very important factor closely related with human's health. To improve the quality of sleep, the verification of design factors affecting the posture of the head and neck is needed, and a pillow design that can induce proper posture is required. Method: This study measured the contact pressures of the two reference groups (bead and cotton pillows) as a method to evaluate the design effectiveness of the contoured pillow. This study proposed 3-dimensional design guidelines by drawing anthropometry (head length) affecting cervical curvature angle (CCA) through the measurement of the participants' cervical curvature angles. Results: In the design effectiveness evaluation, the contact pressure of cervical region was higher than that of a reference group (cotton pillow), and contract area increased, and contract pressure decreased in the shape distributing the occipital region's body pressure. This study proposed pillow's cervical supporting height by percentile of a head length [head length (%tile) (cervical supporting height) affecting the posture of the head and neck: 14.6cm (5%tile) (6.2cm), 15.5cm (25%tile) (6.7cm), 16.4cm (50%tile) (7.1cm), and 19.3cm (75%tile) (8.9cm)]. Conclusion: This study confirmed the contoured pillow's design effectiveness maintaining cervical angle comfortable to sleep with the shape supporting the cervical vertebrae and by reducing the contact load of the occipital region. Also, this study proposed pillow design guidelines based on the 3-dimensional contoured pillow design effectiveness, through which the study laid the foundation for pillow design in a systematic method. Application: The results of this study are expected to be utilized as the basis data by which the optimum pillow type and pillow design according to main percentile can be standardized.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.3
• /
• pp.191-198
• /
• 2014

In this paper, structural integrity evaluation of reactor pressure vessel bottom head without penetration nozzles in core melting accident has been performed. Considering the analysis results of thermal load, weight of molten core debris and internal pressure, thermal load is the most significant factor in reactor vessel bottom head. The failure probability was evaluated according to the established failure criteria and the evaluation showed that the equivalent plastic strain results are lower than critical strain failure criteria. Thermal-structural coupled analyses show that the existence of elastic zone with a lower stress than yield strength is in the middle of bottom head thickness. As a result of analysis, the elastic zone became narrow and moved to the internal wall as the internal pressure increases, and it is evaluated that the structural integrity of reactor vessel is maintained under core melting accident.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.637-642
• /
• 2017

In this study, cold flow and combustion tests are conducted and analyzed to validate designed rocket engine head generating high temperature/pressure steam. At first, uni-injector was designed and manufactured, and cold flow test was conducted. Through this, differential pressure that can supply designed flow rate was confirmed. Also, Each injector's spray pattern were confirmed by patternator. Based on cold flow test results, we selected injectors among the candidates and arranged them on engine head, and cold flow and propellant spray tests were conducted. Finally, combustion test was carried out to analyze the flow rate, pressure, combustion efficiency. As a result, validation of rocket engine head for the development of the high temperature and high pressure steam generator has been completed.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.28 no.3
• /
• pp.51-59
• /
• 2022

Background: This study aimed to investigate the effect of mobilization with movement (MWM) applied to the ankle joint, on the craniovertebral angle (CVA), pressure pain threshold, and neck disability index (NDI) in asymptomatic adults with a forward head posture (FHP). Methods: A total of 32 subjects with FHP were assigned to either the MWM group (N=16) or the cranio-cervical flexion exercise (CCFE) group (n=16). The CVA, pressure pain threshold and NDI were measured before and 4 weeks after the intervention. Results: A significant improvement in the CVA was observed in the MWM group (p<.05), whereas no significant changes (p>.05) were observed in the CCFE group. Both groups showed significant differences in the pressure pain threshold and NDI before and after the intervention (p<.05). Conclusion: The results of the study suggest that MWM applied to the ankle joint can effectively improve the CVA, pressure pain threshold, and NDI of adults with a forward head posture. Based on this study, the ankle MWM technique for dorsiflexion can be used as an objective research method for additional studies targeting FHP patients in the future.

• Journal of the Ergonomics Society of Korea
• /
• v.33 no.2
• /
• pp.143-153
• /
• 2014

Objective: The aim of this study is to investigate the effects of trunk-forearm supported sitting on trunk flexion angle, trunk extensor fatigue and seat contact pressure. Background: The relationship between sitting posture and musculoskeletal disorders of the trunk extensor fatigue and seat contact pressure has been documented. The trunk-forearm support type ergonomic chair was devised from the fact that trunk-forearm support has been reported to reduce trunk extensor activity and discomfort. Method: Using three different sitting postures, upright ($P_1$), trunk-forearm supported ($P_2$) and normal sitting ($P_3$), six healthy subjects participated in the study. Motion capture system was used to collect head and trunk flexion angle, and surface electromyography (sEMG) was used to collect myoelectric signal of upper trapezius, lower trapezius, erector spinae, multifidus, and pressure mat system was used to measure seat contact pressure. Results: When trunk and forearm were supported by the ergonomic chair, higher head flexion angle showed upright > trunk-forearm supported > normal in order, and muscle fatigue showed less than upright and normal sitting. Mean seat contact pressure decreased 19% than upright sitting. But muscle fatigue was not affected by each condition. Conclusion: Trunk-forearm supported sitting of the ergonomic chair showed positive effect in respect of trunk and head flexion angle, trunk extensor fatigue, seat contact pressure. To acquire comprehensive understanding of the effectiveness of the ergonomic chair, further studies such as anatomical effects from measurement of external applied loading effect to the body from interface pressure analysis are required. Application: The results of the publishing trend analysis might help physiological effects of trunk-forearm support type chair.

• Physical Therapy Korea
• /
• v.9 no.1
• /
• pp.63-68
• /
• 2002

Foot ulceration results in substantial morbidity in patients with peripheral neuropathy. The purpose of this study was to find the relationship of plantar foot pressures during walking to plantar ulceration in patients with Hansen's disease. The subjects were recuruited from two Welfare Clinic for Hansen's disease in Wonju and Uiwang city. Ten subjects (5 females, 5 males) with plantar ulceration and a mean age of 63 years were evaluated in this study. The mean duration of Hansen's disease in these subjects was 30 years. Plantar pressures were measured during self-selected comfortable walking speed by using MatScan system. Three subjects had plantar ulceration under the first metatarsal head. Five subjects had plantar ulceration under the second and third metatarsal head. Two subjects had plantar ulcers under the fifth metatarsal head. Eight of 10 subjects had plantar ulceration at highest pressure point that measured during walking. This result suggests that the abnormal high plantar pressure could be related factor to plantar ulceration in patients with Hansen's disease. Also the foot pressure measurement may be useful to evaluate the risk of plantar ulceration in patients with Hansen's disease.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.1016-1020
• /
• 2017

This study was conducted to develop a test facility that simulates the combustion instability that occurs in a real-scale liquid rocket combustor. A separate engine head with 3 injectors arranged in a row was designed/manufactured and verified through preliminary tests. The flow rate and spray pattern of the head were confirmed by the cold flow test. Next, propellant spray test and combustion test were carried out. A preliminary combustion test was carried out at 10 bar and the combustion chamber pressure was measured to be significantly lower than the target pressure. This is because it was a low pressure test, and it is expected to be resolved in the high pressure test in the future.

• The Journal of Korean Physical Therapy
• /
• v.31 no.4
• /
• pp.248-253
• /
• 2019

Purpose: To improve pulmonary function and decrease in balance ability with increasing forward head position and vertebral curvature, we applied Figure-8 brace to confirm the immediate effect on vital capacity and balance and to see if it is applicable. Methods: A total of 34 elderly women aged 65 or older and young women in their 20s with FHP were screened to measure vital capacity, measuring the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), and measuring the foot pressure to see the change in balance. For statistical analysis, the difference between pre and post values was compared using pared t-test. Results: As a result of vital capacity measurements, there was no significant difference between FEV1 and FVC for women over 65 years old (p>0.05). Young women in their 20s had no significant difference in FEV1 (p>0.05), and FVC had significant differences (p<0.05). In measuring foot pressure to measure balance, both women aged 65 and above and young women in their 20s had a significant decrease in anterior foot pressure, and a significant increase in posterior foot pressure (p<0.05). Conclusion: The results of this study did not positively affect the vital capacity of elderly women with FHP. However, the significant increase in vital capacity of young women in their 20s suggests that contraction of the abdominal muscle is necessary during forced expiration. Therefore, it is believed that proper application and therapeutic interventions should be combined when applying Figure-8 brace.

• Korean Journal of Head & Neck Oncology
• /
• v.16 no.1
• /
• pp.9-13
• /
• 2000

Objectives: To determine the tumor interstitial fluid pressure(TIFP) in patients with head and neck cancerand predict radiotherapy outcome.Materials and Methods: In 12 biopsy proven primary head and neck cancer patients with accessible by direct inspection and palpation, and of sufficient thickness(>1cm) to permit accurate needle placement, we measured TIFP at cervical lymph node before and during radiotherapy using a modified wick-in-needle technique. Tumor size was measured clinically and radiologically. Results: The mean preradiotherapy TIFP was 23.4mmHg. Preradiotherapy TIFP had significant relationship with tumor size(p=0.0009). Preradiotherapy TIFP was not different between complete response group and partial or less response group(p=0.114). Radiotherapy outcome was not different between group with above and group with below average TIFP(p=0.09). Conclusion: The mean TIFP was elevated with 23.4mmHg before radiation therapy. Preradiotherapy TIFP had significant relationship with tumor size. It is not definitive that TIFP could be prognostic indicator of radiation response.