• Proceedings of the KWS Conference
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• 2002.10a
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• pp.361-365
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• 2002

Advancements in silicon phase control (SCR) technologies provide an arc welding power supply that has the capability to allow the alteration of the Alternating Current (AC) welding output. These technologies provide a square wave output involving sixteen frequency selections and multiple balance selections. While an AC out put is known to minimize magnetic disturbances associate with Direct Current (DC), the potentials of a non-sinusoidal waveform have not been explored. The focus of the paper is to determine the effects that the frequency and balance of an AC wave form output will have upon a high speed Submerge Arc (SAW) application. The test matrix of the project includes welding .250" steel plate. Joint type is square groove with a travel speed of 65 IPM. Each of the weld parameters was held constant, only the frequency and/or balance were altered between welds. Each frequency/balance combination involved three-gap spacing. Upon completion of the welds the bead profiles were measured and recorded. A relationships/trends were observed with various frequency and balance values. Optimum frequency and balance values were found for the .250" square groove application which permit consistent weld sizing, ease of slag removal, and minimal plate distortion.

• Wind and Structures
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• v.18 no.4
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• pp.323-345
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• 2014

Less than 30 years ago a new method was introduced in wind-tunnel testing of tall buildings, known variously as the High-Frequency Base Balance or High-Frequency Force Balance, which revolutionized the determination of design wind loads using model studies. The method is reviewed in hindsight, in the perspective of the present, and with a crystal ball to speculate on future developments. These viewpoints focus on various technical issues that have been solved, are being solved, and need to be solved. The intent is to assist the uninitiated develop appreciation for the technology involved, to identify various pitfalls awaiting those who embark in the method, and to identify areas of need so that practicing design engineers-the users of such studies-can appreciate the limitations and collaborate on future advances while promoting improved communication between executor and user.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.879-883
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• 2000

A system for measuring and adjusting the oscillating frequency of a balance wheel whick determins the accuracy of mechanical timers. The balance wheel oscillates rotatively suspended by a hair spring which is welded at the other end to the pivot tube. The natural oscillatory frequency of the balance wheel is determined by the length of hairspring from the balance wheel to the point if other parameters the length in the torsional oscillation model are not changed, so the frequency of the balance wheel can be adjusted to meet a requirement by the adjustment of the hairspring length using ultrasonic welding. And the movement of wheel teeth is measured in realtime by a high speed photo fiber sensor and Auto Correlation is used to find a more accurate oscillation period from the measured signal with some variations.

• Wind and Structures
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• v.18 no.4
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• pp.375-389
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• 2014

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

• The Journal of Korean Physical Therapy
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• v.34 no.5
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• pp.205-211
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• 2022

Purpose: This study investigated the effects of an intervention that combined the abdominal drawing-in maneuver and frequency-specific neuromuscular electrical stimulation on changes in trunk muscle activity, muscle fatigue, and balance in stroke patients. Methods: Thirty stroke patients were randomly assigned to two groups. Fifteen subjects were assigned to group I which performed the abdominal drawing-in maneuver combined with low-frequency neuromuscular electrical stimulation and the other 15 subjects to group II where the abdominal drawing-in maneuver was combined with high-frequency neuromuscular electrical stimulation. Muscle activity and fatigue were measured using surface electromyography before the intervention. Balance was measured using the Trunk Impairment Scale and re-measured after six weeks of intervention for comparative analysis. Results: Both groups showed a significant increase in muscle activity and balance (p<0.05), and there was no significant difference between the groups (p>0.05). In the changes in muscle fatigue, only the experimental group II showed a significant increase in muscle fatigue (p<0.05). The difference between the groups was statistically significant (p<0.05). Conclusion: It was confirmed that among stroke patients, the combination of the abdominal drawing-in maneuver and low-frequency neuromuscular electrical stimulation was more effective in changing the muscle activity and balance of the trunk by minimizing the occurrence of muscle fatigue compared to the combination of the abdominal drawing-in maneuver and high-frequency stimulation. These results can be used as basic data for clinical trunk stabilization training.

• Wind and Structures
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• v.18 no.4
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• pp.457-471
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• 2014

A summary of the main results from an international comparative study for the high-frequency base balance is given. Two buildings were specified - a 'basic' and an 'advanced' building. The latter had more complex dynamic response with coupled modes of vibration. The predicted base moments generally showed good agreement amongst the participating groups, but less good agreement was found for the roof accelerations which are dominated by the resonant response, and subject to measurement errors for the generalized force spectra, to varying mode shape correction techniques, and different methods used for combining acceleration components.

• Journal of Magnetics
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• v.19 no.2
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• pp.192-196
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• 2014

The aim of the present study was to examine the effects of high and low frequency repetitive transcranial magnetic stimulation on motor cortical excitability and the balance function in subacute stroke patients. Twenty-four subjects were randomly assigned to either the high frequency (HF) rTMS group, or the low frequency (LF) rTMS group, with 12 subjects each. All subjects received routine physical therapy. In addition, both groups performed a total of 20 sessions of rTMS for 20 minutes, once a day, 5 times per week, for a 4-week period. In the HF rTMS group, 10 Hz rTMS was applied daily to the hotspot of the lesional hemisphere; and in the LF rTMS group, 1 Hz rTMS was applied daily to the hotspot of the nonlesional hemisphere. Motor cortex excitability was determined by motor evoked potentials, and the balance function was evaluated by use of the Balance Index (BI) and the Berg Balance Scale (BBS), before and after the intervention. The change rate in the value of each variable differed significantly between the two groups (p<0.05). Furthermore, significant differences were observed between all post-test variables of the two groups (p<0.05). In the HF rTMS, significant differences were found in all the pre- and post-test variables (p<0.05). On the other hand, in the LF rTMS, significant difference was observed only between the pre- and post-test results of BI and BBS (p<0.05). The findings demonstrate that HF rTMS can be more helpful in improving the motor cortical excitability and balance function of patients with subacute stroke treatment than LF rTMS, and that it may be used as a practical adjunct to routine rehabilitation.

• Journal of Nutrition and Health
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• v.24 no.2
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• pp.132-141
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• 1991

The purpose of this study was to choose the assessment method of usual energy in take for epidemiological study. Energy intakes of 30 female college students estimated by frequency questionnaires and energy balance method were compared with that obtained by dietary record. The results are summarized as follows. Assessment of mean energy intakes by dietary record frequency questionnaires energy balance method were 156.2Kcal, 1517Kcal, 1878.0Kcal respectively. There was no significant difference between energy intake by dietary record and that by frequency questionnaire. Frequency questionnaire covers 4 weeks energy intake and it can be substituted for dietary record. Although energy intake by energy balance method was significantly different from that obtained by dietary record it shows high correlation with anthropometric and obesity indices and energy expenditure of the subjects.

• Physical Therapy Korea
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• v.25 no.3
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• pp.27-38
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• 2018

Background: At present time, smartphones have become very popular and powerful devices, and smartphone applications with the good validity have been designed to assess human balance ability. Objects: The purpose of this study is to evaluate the feasibility of smartphone acceleration in the assessment of postural control ability for six different conditions. Methods: Twenty healthy college-aged individuals volunteered. Static balance ability was measured twice with one-day interval using smartphone application and 3D motion capture system under the six different conditions. Results: Dominant frequencies for each test condition did not show significant differences except for two conditions. The intra-rater correlation coefficient between the first and second tests showed high correlations in six conditions(r>.70, p<.05). Smartphone acceleration and the acceleration calculated from the 3D marker position data showed high correlation coefficient(r>.80, p<.001). Conclusion: Acceleration recorded from a smartphone could be useful assessment variables for balance test in the clinical field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1740-1748
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• 2011

The purpose of this study was to investigate effects of the long-term high-frequency transcutaneous electrical nerve stimulation(TENS) on the spasticity and the balance in chronic stroke patients. Twenty-six subjects with spasticity over lower limbs were allocated randomly into two groups under standard rehabilitation: (1) TENS group, (2) placebo-TENS group. TENS stimulation was applied on the both the gastrocnemius for 30 minutes, 5 days a week for 4 weeks(100 Hz, 0.25 ms, 2 times sensory threshold). The Modified Ashworth Scale(MAS) and Hand-held manual muscle tester were used to assess the ankle plantarflexor spasticity. Balance function under three conditions was measured by using force-plate and the amount of postural sway was assessed; in (1) the condition of standing with eyes opened, (2) with eyes closed and (3) the condition of standing on unstable surface with eyes opened. Both groups showed significant improvement in spasticity and balance function after treatment for 4 weeks(p<.05). Especially, TENS group showed a significant reduction of spasticity compared to placebo-TENS group(p<.05). These results suggested that additional stimulation of a long-term high-frequency TENS to standard rehabilitation induced an improved balance function and a spasticity reduction. The long-term application of high-frequency TENS will be an effective intervention for reducing spasticity and increasing balance ability in the chronic stroke patients.