• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3686-3694
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• 1996

A numerical investigation of natural convection flow along irregular vertical surfaces is reported. A transformation method is applied to the problem of natural convection under the assumption of a large Grashof number. A vertical wavy surface is used as an example to demonstrate the advantages of the transformation method, and to show the heat transfer mechanism near such surfaces. Surface non-uniformities on the boundary layer flow induced by a constant was temperature, semi-infinite surface are investigated. Also the effects of Prandtl number, flow index, and surface amplitude in Non-Newtonian fluids are discussed. When possible, the comparison of the numerical results shows a good agreement. The amplitude is proportional to the amplitude of a wavy surface. The results demonstrate that the local heat flux along a wavy surface is smaller than that of a flat surface. The frequency of the wavy surface is half that of the local heat transfer rate. The amplitude of the local Nusselt number gradually decreases downstream where the natural convection boundary layer grows thick.

• Annals of Clinical Neurophysiology
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• v.7 no.2
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• pp.83-87
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• 2005

Background: The study of the medial antebrachial cutaneous nerve (MABCN) is an underused electrodiagnostic tool. But its use is often crucial for assessing mild lower brachial plexus or MABCN lesions, and sometimes for differentiating an ulnar mononeuropathy from a lower brachial plexopathy. This study was designed to know the difference of amplitude and velocity in a stimulation method (orthodromic vs antidromic), side of an arm and sex according by age. Method: MABCN conduction studies were performed orthodromically and antidromically in 90 subjects (42 women and 48 men, ranging from 22 to 79 years of age). We divided subjects into three groups by age (group 1: 20-39 years, group 2: 40-59 years, group 3: 60-79 years). The mean sensory nerve action potential amplitudes and sensory nerve conduction velocities in each group was compared by stimulation method, side of an arm and sex. Result: The amplitudes and velocities made a significant difference between orthodromic and antidromic method in all age groups. At comparison in amplitude and velocity by side of an arm, only amplitude was significantly higher in right arm than left by any stimulation method. The amplitudes and velocities were of no statistically differences in sex except amplitude checked orthodromically in right arm. Conclusion: This study suggests that there is the differences in conduction study of MABCN by stimulation method and side of an arm.

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.599-605
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• 2003

For practical calculations, the Reynolds equation is frequently used to analyze the lubricating flow. The full Navier-Stokes Equations are used to find validity limits of Reynolds equation in a lubricating flow regime by result comparison. As the amplitude of wavy upper wall increased at a given average channel height, the difference between Navier-Stokes and lubrication theory decreased slightly : however, as the minimum distance in channel throat increased, the differences in the maximum pressure between Navier-Stokes and lubrication theory became large.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.324-329
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• 1997

This paper introduces experimental results of ride values assessed for domestic and overseas passenger cars. The experiment was executed about four vehicles, three Korean persons, and two roads by measuring human 12-axis. The results include the comparison of the component ride values, overall ride value, and seat effective amplitude transmissibility. The relative comparison of the ride values for different cars is shown in this paper, which may lead us to judge the current address of Korean ride quality-related technology.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.257-264
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• 2012

Objectives: This study's aims were to evaluate the effects of load center of gravity within an object lifted and feet placements on peak EMG amplitude acting on bilateral low back muscle groups, and to suggest adequate foot strategies with an aim to reducing low back pain incidence while lifting asymmetric load. Methods: The hypotheses that asymmetric load imposes more peak EMG amplitude on low back muscles contralateral to load center of gravity than symmetric load and maximum peak EMG amplitude out of bilateral ones can be relieved by locating one foot close to load center of gravity in front of the other were established based on biomechanics including safety margin model and previous researches. 11 male subjects were required to lift symmetrically a 15.8kg object during 2sec according to each conditions; symmetric load-parallel feet (SP), asymmetric load-parallel feet (AP), asymmetric load-one foot contralateral to load center of gravity in front of the other (AL), and asymmetric load-one foot ipsilateral to load center of gravity in front of the other (AR). Bilateral longissimus, iliocostalis, and multifidus on right and left low back area were selected as target muscles, and asymmetric load had load center of gravity 10cm deviated to the right from the center in the frontal plane. Results: Greater peak EMG amplitude in left muscle group than in right one was observed due to the effect of load center of gravity, and mean peak EMG amplitudes on both sides was not affected by load center of gravity because of EMG balancing effect. However, the difference of peak EMG amplitudes between both sides was significantly affected by it. Maximum peak EMG amplitude out of both sides and the difference of peak EMG amplitude between both sides could be reduced with keeping one foot ipsilateral to load center of gravity in front of the other while lifting asymmetric load. Conclusions: It was likely that asymmetric load lead to the elevated incidence of low back pain in comparison with symmetric load based on maximum peak EMG amplitude occurrence and greater imbalanced peak EMG amplitude between both sides. Changing feet positions according to the location of load center of gravity was suggested as one intervention able to reduce the low back pain incidence.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.2
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• pp.129-135
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• 2018

PURPOSE: The imbalance of pretibial muscles can be a factor contributing to the development of pes planus. However, no study has yet compared the muscle activity of the tibials anterior (TA) to that of the extensor digitorum longus (EDL). The purpose of this study was to determine whether there are differences in the electromyographic (EMG) TA and EDL amplitude indexes (AIs) between normal and pes planus feet. METHODS: A total of 14 subjects with normal feet and 15 subjects with bilateral pes planus participated in this study. TA and EDL muscle activities were measured using a wireless EMG system and the angles of ankle dorsiflexion and eversion of the subtalar joint were measured using a universal goniometer during active ankle dorsiflexion in the prone position. AI was calculated as follows: $\text{amplitude_{TA}-amplitude_{EDL}/(amplitude_{TA}+amplitude_{EDL})}/2{\times}100$. RESULTS: The AIs of the TA and EDL were significantly lower in pes planus feet than in normal feet (p<.05). The angle of subtalar eversion was significantly greater in pes planus feet than in normal feet during active ankle dorsiflexon (p<.05). However, there was no significant difference in the angle of ankle dorsiflexion between normal feet and pes planus feet (p>.05). CONCLUSION: This study showed that TA muscle activation was lower in pes planus feet than in normal feet, resulting from greater eversion range of motion during active ankle dorsiflexion. We suggest that the imbalance of ankle dorsiflexors must be considered in pes planus management.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.112-118
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• 2013

The selection of appropriate ground motions and reasonable modification are becoming increasingly critical in reliable prediction on seismic performance of structures. A widely used amplitude scaling approach is not sufficient for robust structural evaluation considering a site specific seismic hazard because only one spectral value is matched to the design spectrum typically at the structural fundamental period. Hence alternative approaches for ground motion selection and modifications have been suggested. However, there is no means to evaluate such methodologies yet. In this study, it is focused to describe the main questions resided in the amplitude scaling approach and to propose a regression model for structural damage as point of comparison. Spectrum compatible approach whose resulting spectrum matches the design spectrum at the entire range of the structural period is considered as alternative to be compared to the amplitude scaling approach. The design spectrum is generated according to ASCE7-05.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.135-139
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• 2008

Purpose: This study was designed to compare the accommodative amplitude whose 40s initial presbyopia patients divided into five occupation (driver, official worker, housewife, field worker, teacher). Methods: Both "push-up"and "inus lens to blur technique" methods were used to examine the average of accommodative amplitude. Results: All the average of accommodative amplitude (OD, OS, and OU) were the lowest in official worker group (3.27${\pm}$0.21D, 3.31${\pm}$0.22D, 3.54${\pm}$0.28D) and the highest in housewife group (4.07${\pm}$0.35D, 4.11${\pm}$0.35D, 4.37${\pm}$0.39D). Conclusions: Because occupational specifications including a fixative habit are able to change the binocular accommodation, it is important to understand thoroughly the patient's occupation when opticians make near vision prescription for initial presbyopia.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.51-56
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• 2021

In this paper, performance degradation in the cross-eye jamming due to amplitude mismatch of two jamming antennas is considered. The mismatch of the amplitude ratio is modeled as a random variable with a normal distribution of the difference between the actual amplitude ratio and the nominal amplitude ratio due to mechanical defects. In the proposed analytic performance analysis, the first-order Taylor series expansion and the second-order Taylor series expansion is adopted. Performance measure of the cross-eye jamming is the mean square difference (MSD). The analytically derived MSD is validated by comparing the analytically derived MSD with the first-order Taylor series-based simulation-based MSD and the second-order Taylor series-based simulation-based MSD. It shows that the analysis-based MSD is superior to the Monte-Carlo-based MSD, which has a high calculation cost.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2044-2045
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• 2008

This paper was studied fault possibility of glass insulator through the proper vibration and field vibration comparison. The proper vibration of 1 cell glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. From the FFT analysis of viaduct and open route, in the case of positive direction, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in the case of negative direction, the vibration did not cause big effect. In comparison with the proper vibration of glass insulator, the resonance was not observed.