• Design & Manufacturing
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• v.10 no.2
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• pp.18-23
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• 2016

Injection molded thermoplastic parts may need to be coated to facilitate paint adhesion, or to satisfy other surface property requirements, such as appearance, durability, and weather resistance. In this paper, a two-component polyurethane metering system was developed for the simultaneous injection and surface coating of a plastic substrate. The system was composed of storage tanks, feed pumps, axial piston pumps, mixing head. The tank was designed to be double-jacket structured and fabricated for polyol and isocyanate, respectively. A temperature chamber was used to maintain the material temperature to be $80^{\circ}C$ during flowing from storage tank to mixing head. Inside the chamber, feed pump, low pressure filter, high pressure pump, high pressure filter, pressure sensor, flow meter were installed. A mixing head of L-type was used for homogeneous mixing of polyol and isocyanate. Inside the mixing head, a cartridge heater and a temperature sensor were installed to control the temperature of the materials. The flow rate of axial-piston pump was controlled by using closed-loop feedback control algorithm. The input flow-rates were compared with the measured values. The output error was 6.7% for open-loop control, whereas the error was below 2.2% for closed-loop control. In addition, the pressure generated through mixing-head nozzle increased with increasing flow rate. It was found that the pressure drop between metering pump and mixing-head nozzle was almost 10 bar.

• The Journal of the Acoustical Society of Korea
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• v.25 no.1E
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• pp.25-31
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• 2006

Two twin microphones may produce particular patterns of binaural directivity by time delays between the twin microphones. The boundary element method (BEM) was used for the simulation of the sound pressure field around the KEMAR head model in order to quantify the acoustic head effect. The sound pressure onto the microphone was calculated by the BEM to an incident sound pressure. Then a planar directivity pattern was formed by four sound pressure signals from four microphones. The optimal binaural directivity pattern may be achieved by adjusting time delays at each frequency while maintaining the forward beam pattern is relatively bigger than the backward beam pattern. The simulation results were verified by the experimental measurement.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.115-122
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• 2005

Two twin microphones may produce particular patterns of binaural directivity by time delays between twin microphones. The boundary element method (BEM) was used for the simulation of the sound pressure field around the head model in order to quantify the acoustic head effect. The sound pressure onto the microphone was calculated by the BEM to an incident sound pressure. Then a planar directivity pattern was formed by four sound pressure signals from four microphones. The optimal binaural directivity pattern may be achieved by adjusting time delays at each frequency while maintaining the forward beam pattern is relatively bigger than the backward beam pattern.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.13-21
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• 2001

The effect of water spray for the fire sprinkler depends on droples distribution over maximum possible floor area. The present study are carried out for the characteristics of water spray and droplets experimentally and numerically km two fire sprinkler heads which are CHM head and CHl heal CHl head is self-production and CHl head is widely used up to date. As the result of using CHM head, water spray and droplets are distributed over large area because CHM head has smooth surface and non-flamed shape. When the pressure of fire sprinkler head is low, SMD(sauter mean diameter) is large and when the pressure of fire sprinkler head is high, SMD is small.

• The Journal of Korean Physical Therapy
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• v.14 no.1
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• pp.117-124
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• 2002

Poor posture of the neck and head long been recognized as a factor contributing to the onset and perpetuation of pain in the head and neck region. The purposes of the study were to evaluate the changes in forward head posture and pressure pain threshold in tension type headache group and control group. Forward head posture were measured to craniovertebral angle and cranial rotation angle. Craniovertebral angle was smaller in tension type headache group(p<0.05), and cranial rotation angle was larger in tension type headache group(p<0.05). Pressure pain threshold was similar between tension type headache group and control group with the exception of right suboccipitalis and left temporalis(p<0.05).

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.121-129
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• 2019

PURPOSE: This study was conducted to measure the effects of cervical stabilization exercises on neck pain, forward head posture, and the acoustic characteristics frequency and amplitude modulation of patients with chronic neck pain caused by forward head posture using pressure biofeedback. METHODS: 20 patients with chronic neck pain and voice disorders presenting at the S Exercise Center in Daegu, Korea, were included in the study. A cervical stabilization exercise program of 50 minutes per session was performed three times a week for eight weeks. Pressure biofeedback was utilized to determine the impact of the exercises on neck pain, forward head posture, and the acoustic characteristics of the patients. The measurements were taken prior to and after the intervention to determine any changes. RESULTS: A significant improvement in neck pain, craniovertebral angle and the acoustic characteristics frequency and amplitude modulation of the patients was demonstrated after the intervention (p<.05). CONCLUSION: Cervical stabilization exercises were demonstrated to have a significantly positive effect on neck pain, forward head posture, and vocalization stability in patients with chronic neck pain in the current study based on measurements taken using a pressure biofeedback system. This indicates that an improvement in forward head posture positively impacts postural stability and vocalization. Future studies investigating a greater range of interventions designed to improve neck pain and acoustical effects in patients with chronic neck pain and forward head posture patients are warranted.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.211-217
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• 2017

Objective: The purpose of this study was to investigate the effect of a 12-week professional body massage program (PMP) on forward head posture, neck pain, and plantar foot pressure balance in men in their 20s. Method: A total of 20 men with musculoskeletal diseases were recruited for this study. The participants were asked to take part in a PMP twice a week for 12 weeks. The cranial vertical angle (CVA) for forward head posture and visual analogue scale (VSC) for neck pain and right/left foot plantar pressure balances were extracted to compare between pre- and post-program differences. Results: CVAs before ($56.86{\pm}4.55^{\circ}$) and after ($62.72{\pm}4.57^{\circ}$) and VSCs before ($6.95{\pm}1.70$) and after ($1.70{\pm}1.56$) PMP revealed statistically significant differences. The right foot, after PMP, showed a significant increase in the plantar pressure balance from $46.17{\pm}2.95$ to $49.44{\pm}1.29%$, while the left foot decreased significantly from $53.83{\pm}2.95%$ to $50.56{\pm}1.29%$. Therefore, based on these results, it may be said that the foot pressure balance abilities were improved after PMP because the ideal foot pressure ratio is 50%. Conclusion: Consequently, it was suggested that a 12-week PMP could be utilized for improvement of forward head posture, neck pain, and foot plantar pressure balance in men in the 20s with musculoskeletal diseases.

• The Journal of Korean Physical Therapy
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• v.34 no.4
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• pp.155-160
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• 2022

Purpose: This study was to identify the effect of cervical stabilization exercise with visual feedback on the craniovertebral angle and foot pressure in subjects with forward head posture. Methods: Thirty healthy adults were recruited in the study. Participants were randomly assigned to the stabilization exercise with visual feedback (SE-VF) group (n=15) or stabilization exercise (SE) group (n=15). The SE-VF group performed cervical stabilization exercise while sitting on a chair without a backrest and checking their side profile in real time a monitor 3m away. The SE group performed the same cervical stabilization exercise as the SE-VF group accompanied by without visual feedback. Craniovertebral angle (CVA) was measured to quantify forward head posture, and the foot pressure of the subjects were evaluated. Results: The foot pressure showed statistically significant differences pre and post in both midfoot and left metatarsal only in SE-VF group (p<0.05). Conclusion: These findings of this study showed that the cervical stabilization exercise with visual feedback was effective for the foot pressure of subjects. In addition, based on the results of this study, it is suggested that visual feedback will be effective in cervical stabilization exercise.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.437-446
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• 2023

We propose a transient evaluation scheme using a pressure measurement in a complicate pipeline systems. Conservation of mass and momentum equations in time domain can be transformed into a pressure head and flowrate relationship between upstream and downstream point in frequency domain. The impedance formulations were derived to address measured pressure at downstream to evaluate of flowrate or pressure head at any point of system. Both branched pipeline element and looped pipeline element can be generally addressed in the platform of the basic reservoir pipeline valve system. The convolution of time domain response function with measured pressure head from a downstream point provides flowrate or pressure head response in any point of the designated pipeline system. The proposed method was validated through comparison between traditional method of characteristics and the proposed method in several hypothetical systems.

• Journal of Clinical Otolaryngology Head and Neck Surgery
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• v.29 no.2
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• pp.182-189
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• 2018

Background and Objectives : There were few literatures about the relationship between upper airway disorders and cardiovascular risk factors such as hypertension, although an association between impaired lower respiratory function and cardiovascular alterations was often reported. Our purpose was to assess the relationships between chronic sinusitis and hypertension. Materials and Methods : Three hundred subjects with bilateral chronic sinusitis who underwent functional endoscopic sinus surgery between 2015and 2017 were evaluated. Six hundred forty subjects without any nasal diseases were enrolled as a control group. Blood pressure and body mass index (BMI) were measured using a standardized method, and subjects were asked about current use of any antihypertensive medication, history of diabetes, smoking and alcohol drinking habits.Sinusitis group was assessed by nasal endoscopic examination, paranasal sinus CT scan and allergy test. Results : Average systolic and diastolic blood pressures were statistically significantly higher in subjects with sinusitis than control group. Chronic rhinosinusitis was associated with a 1.415-fold (95% confidence interval 1.053-1.930) increased hazard of hypertension after multivariate adjustment. Conclusions : These results suggest that sinusitis is associated with high blood pressure. Therefore patients with sinusitis may need special attention for blood pressure control. Further studies need to be performed to elucidate the pathogenesis behind such associations.