• The Journal of Korean society of community based occupational therapy
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• v.10 no.2
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• pp.1-9
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• 2020

Objective : The purpose of this study was to establish the concurrent validity of the Korean Occupational Balance Assessment(OBA) tool. Methods : This study was conducted on 1016 people from October 1 to October 25, 2019. Data collection was performed using OBA and Occupational Balance Questionnaire11(OBQ11). The data were analyzed by descriptive statistics, Pearson correlation. Results : There was a significant correlation between the scores of the three areas of OBA and the total score of OBQ11(p<.01). All three areas were analyzed with positive correlations. The time use area (r = .554) and occupation frequency area (r = .574) were found to be correlated. Most of the sub-factors in the occupation characteristics area (importance r = .582, goal achievement r = .633, enjoyment r = .649, health r = .650) were analyzed with high correlation. Conclusion : OBA has proven to be a valid and reliable assessment tool for measuring occupational balance. Further research needs to provide guideline on occupational balance for usefulness in clinical area.

• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.101-108
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• 2005

The investigations for mitigating wind-induced excitations of tall buildings have been carried out. The aerodynamic modification of a building shape changing the cross-section with height through tapering, which alters the flow pattern around the building, could reduce wind induced excitations of tall buildings. The fart that a tapered tall building might spread the vortex-shedding over a broad range of frequencies makes more effective for reducing acrosswind responses has been established. In this paper, to investigate the tapering effect for reducing wind-induced responses of a tapered tall building, high-frequency force-balance test was conducted. The six types of building models which have different taper ratio of 2.5%, 5%, 7.5%, 10%, 15% and one basic building model of a square cross-section were tested under the two typical boundary layers representing suburban and urban flow environment. The effect of wind direction was also considered.

• Journal of Power Electronics
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• v.9 no.2
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• Wind and Structures
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• v.18 no.4
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• pp.391-422
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• 2014

The high frequency force balance (HFFB) technique provides convenient measurements of integrated forces on rigid building models in terms of base bending moments and torque and/or base shear forces. These base moments or forces are then used to approximately estimate the generalized forces of building fundamental modes with mode shape corrections. This paper presents an analysis framework for coupled dynamic response of tall buildings with HFFB technique. The empirical mode shape corrections for generalized forces with coupled mode shapes are validated using measurements of synchronous pressures on a square building surface from a wind tunnel. An alternative approach for estimating the mean and background response components directly using HFFB measurements without mode shape corrections is introduced with a discussion on higher mode contributions. The uncertainty in the mode shape corrections and its influence on predicted responses of buildings with both uncoupled and coupled modal shapes are examined. Furthermore, this paper presents a comparison of aerodynamic base moment spectra with available data sets for various tall building configurations. Finally, e-technology aspects in conjunction with HFFB technique such as web-based on-line analysis framework for buildings with uncoupled mode shapes used in NALD (NatHaz Aerodynamic Loads Database) is discussed, which facilitates the use of HFFB data for preliminary design stages of tall buildings subject to wind loads.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.111-121
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• 1997

The spectral energy balance model is composed and the nonlinear interaction is approximated by the discrete interaction parameterization as in WAM model. The numerical results of durational limited growth test agree very well with those of the exact model, EXACT-NL. The response of a wave spectrum to a change in wind direction is investigated numerically for a sequence of direction changes 30$^{\circ}$ , 45$^{\circ}$ , 60$^{\circ}$ , 90$^{\circ}$ . The high frequency components relax more repidly to the new wind direction than the low frequency components and the relaxation process also depends on the wave age. For wind direction changes less than 60$^{\circ}$ , the coupling by nonlinear interaction is so strong that the secondary peak in input source distribution is counteracted by the negative lobe of the nonlinear interaction. For wind direction changes grater than 60$^{\circ}$ , a second independent wind-sea spectrum is generated in the new wind direction, while the old spectrum gradually decays as swell.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.2
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• pp.127-134
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• 2002

A Study on the application of ultrasonic with high frequency is carried out as a plan to rise the efficiency of the hydrogen fuel production in an electrolysis of water. KOH is selected as an electrolyte and concentrations are 0 %, 10 %, 20 %, and 30%. The solvent is city water. A measurable device of buoyancy by an electronic balance and a measurable device of voltage with a sensor of pressure are planned newly as a measuring device to measure the quantity of hydrogen production. An ultrasonic transducer with high frequency of 2 MHz is selected to give them the ultrasonic forcing. In results, it is clarified that ultrasonic influences the decrease of overpotential in the electrolytic solution. And basic data according to the pole interval and the temperature are obtained.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.83-88
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• 2004

High voltage AC electric field has been applied to turbulent propane jets to investigate the effect of electric field on liftoff characteristics. Liftoff velocity and liftoff height have been measured by varying the applied voltage and frequency. Liftoff velocities were delayed and liftoff heights were reduced by applying AC, not by DC. The electric effect became disappeared with further increasing jet velocities, which shows that the effect can be explained by the balance between inertia force and electric force. The flame stabilization effect was intensified as either applied voltage or frequency increased. Plasma streamers were generated between the flame and the jet under high voltage conditions. Liftoff velocity in the absence of plasma can be well correlated by the function of voltage and frequency.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.4
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• pp.241-247
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• 2009

Purpose：The purpose of this study is to investigate the effect of transcutaneous electrical stimulation on autonomic nervous system using heart rate variability analysis. Methods：31 subjects were evaluated with HRV before and after a single high-frequency TENS for 15minutes treatment. The standard deviation of all the normal RR-interval(SDNN) and lower frequency/high frequency ratio(LF/HF ratio) were recorded with TAS-9. Results：After single TENS treatment, autonomic adaptation as analyzed by SDNN was increased from $42.47\pm12.96$ to $4.43\pm16.76$(p>0.05) and autonomic balance as analyzed by LF/HF ratio was increased from $1.4\pm0.45$ to $1.45\pm0.41$(p>0.05). Conclusion：In this study, SDNN and LF/HF ratio changed in health young students as a result of single TENS treatment. But there is no significant difference between pre-treatment and post-treatment of SDNN and LF/HF ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.183-193
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• 2003

Micro-weighing device by using null balance method is being essential part in fields of high-technology industries such as precision semiconductor industry, precision chemistry, biotechnology and genetics etc. Also, requirements for high resolution and for large measurement range increase more and more. The performance of the micro-weighing device can be determined by the mechanism design and analysis. The analytical design method has been proposed for the performance improvement such as resolution, measurement range and fast response. The 2-stage displacement amplification is designed to overcome the limit of conventional force transmitting lever. The parallel spring is designed for the measurement result independent of the input force position variation. Also, the natural frequency of mechanism is analyzed for the fast response. After each analysis, optimal design has been carried out. To verify the analysis and design result, characteristics experiments had been carried out after construction. Finally, the system had been controlled.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.9
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• pp.919-929
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• 2014

In recent, the requirements for the safety to the effects of high power electromagnetic wave have been increased along with the development of electricity and electronic equipments. The small sized electronic devices and the various components have been analyzed by using the full-EM simulation and solving a complete set of Maxwell equation. However, the deterministic approach has a drawback and much limitation in the electromagnetic analysis of an electrically large cavity with a high complexity of the structure. In this paper, statistical theory and topological modeling method are combined to analyze the large cavity with a complex structure. In particular, the PWB(Power Balance) method and BLT(Baum-Liu-Tesche) equation are combined and employed to solve the frequency response to the large-scaled cavity with remarkably reduced time-consumption. For instance, a PCB substrate inside box of box are considered as a large structure with a complexity.