• Earthquakes and Structures
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• v.2 no.2
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• pp.171-187
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• 2011

Rational scaling of design earthquake ground motions for tall buildings is essential for safer, risk-based design of tall buildings. This paper provides the structural designers with an insight for more rational scaling based on drift and input energy demands. Since a resonant sinusoidal motion can be an approximate critical excitation to elastic and inelastic structures under the constraint of acceleration or velocity power, a resonant sinusoidal motion with variable period and duration is used as an input wave of the near-field and far-field ground motions. This enables one to understand clearly the relation of the intensity normalization index of ground motion (maximum acceleration, maximum velocity, acceleration power, velocity power) with the response performance (peak interstory drift, total input energy). It is proved that, when the maximum ground velocity is adopted as the normalization index, the maximum interstory drift exhibits a stable property irrespective of the number of stories. It is further shown that, when the velocity power is adopted as the normalization index, the total input energy exhibits a stable property irrespective of the number of stories. It is finally concluded that the former property on peak drift can hold for the practical design response spectrum-compatible ground motions.

• The korean journal of orthodontics
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• v.15 no.2
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• pp.197-209
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• 1985

To investigate the relationship between the pubertal spurt in body height and bone maturity of the hand-and-wrist in normal occlusion, the author X-rayed the hand-and-wrists of 1,141 students (male 614, female 527) and assessed their bone maturity. In this study, eleven skeletal stages were selected. The bones used to determine skeletal maturity were the ulnar sesamoid of the metacarpophalangeal joint of the first finger, the epiphyses of the proximal, middle, distal phalanges of the third finger, and middle phalanx of the fifth finger, and distal epiphysis of the radius. From the longitudinal data for height, an assessment was made of the change in growth velocity. The pubertal growth stage was divided into onset and peak height velocity phases. The results were as follows; 1. The onset of the pubertal growth was between the $PP_3=\;and\;MP_3=$ stage for boys, and between the $MP_3=\;and\;MP_5=$ stage for girls; the mean age of onset was 10.6 years for boys and 9.0 years for girls. 2. The peak height velocity was between the S and $MP_{3_{cap}}$ stage for boys, and between the $MP_{3_{cap}}$ and $MP_{5_{cap}}$ stage for girls; the mom age of peak height velocity was 12.5 years for boys and 10.9 years for girls. 3. As the stages of bone maturity progressed from $DP_{3u},\;to\;PP_{3u},\;MP_{3u}$, Ru, the peak height velocity had been reached, and the growth rate retarded, therefore the approach to full physical maturity was attained. 4. The evidence for the period of onset, peak height velocity and bone maturation suggested that girls were in advance of boys. During the latter part of pubertal growth, the rate of boys' bone maturation was faster than that of girls'.

• Journal of The Korean Astronomical Society
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• v.29 no.1
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• pp.75-81
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• 1996

We mapped the $^{13}CO$ line in the dark nebula L134 using the 14-m Taeduck radio telescope with a 57 arcsec beam and one beam spacing. The cloud has a spherical shape with an intensity peak ridge extended from the northwest to the southeast directions. The halfwidth and the radial velocity of the lines peak at the region of the cloud center. The radial velocity decreases from the cloud center towards the north and south directions. The integrated line intensity distributions in the space-velocity plane show some structure and a velocity gradient. The $^{13}CO$ and $H_2CO$ clouds and dark clouds are closely related in space in shape, outer boundary, and intensity peak positions. The $^{13}CO$ integrated line intensity is linearly proportional to the visual extinction.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.749-757
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• 2005

The present study analyzed actual cases of designed flow estimation method and designed flow rate of sewage pipe lines. In order to examine the effects of peak-hour demand factor estimation with given daily highest peak loading, we analyzed its effects on designed flow rate with changing the peak-hour demand factor from 2.0 to 10.0. The results of this study are as follows. When reviewing the recent designs, we found that 59.4% of pipe line with 250mm and 300mm diameter, which fall under minimum allowable pipeline did not meet the minimum velocity which is specified as 0.6m/sec in design standards. The pipe line that have minimal access population or have very low slope did not satisfy the minimum velocity. In estimating the designed sewage flow, the applied daily highest peak loading and hourly highest peaking loading were the load factor for the entire population of the planned area, and for the peak loading of the initial pipes connected to a very small population, we applied the same factor as that applied to the entire area and, as a result, the hourly highest flow was underestimated. Because, in case of the initial pipes, the method of applying the same peak loading to all subject areas is highly possible to produce underestimated design flow, when estimating the designed flow of the initial pipes connected to a small population need to adopt a rational flow factor according to the size of population. For this, it is considered to investigate and analyze raw data on daily and hourly variation of sewage flow.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.61-68
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• 2007

The purpose of this study was to analyze the shoulder joint torque and muscle pattern performing as Tennis serve by Isokinetic motions on Isomed 2000. The subject, who was 5 males Korean national high school tennis players. By analyzing the flexion/extension of the shoulder, the peak torque of the internal/external rotation motion(at 60,180 and 300 degree/sec) at peak torque degree, the weight, peak torque, and power. combined with the timing of the electrode of the attached trapezius and posterior deltoid at the three part. From the data analysis & discussion the following conclusions were drawn. When doing a shoulder extension, the peak torque can be widely seen at 60degree per second. However the degree may be different depending on angular velocity. When doing an internal rotation at 90degree abduction, peak torque per weight was seen at 60degree per second. The degree of peak torque was at 31.6-44.2 and peak power was faster when angular velocity was increased. The aspect of muscle pattern was seen more at the internal rotation in the 90degree abduction rather than the shoulder extension. However the angular velocity was not influenced by muscle mobilization(in order of anterior deltoid, posterior deltoid and trapezius. To properly apply the above conclusion, when tennis players serve it is better the elbow be impacted by the extension. when doing isokinetic motion it is better to increase angular velocity and improve muscle power. also the anterior deltoid amongst the shoulder muscle should be improved to develop serve speed.

• Geomechanics and Engineering
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• v.11 no.5
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• pp.713-723
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• 2016

Shear wave velocities of three selected sandy soils subject to drained triaxial compression test were continuously measured using the bender elements. The shear wave velocity during isotropic compression, as widely recognized, increased as confining pressure increased and they were correlated well. However, during drained shearing, the mean effective stress could no further provide a suitable correlation. The shear wave velocity during this stage was almost constant with respect to the mean effective stress. The vertical stress was found to be more favorable at this stage (since confining stress was kept constant). When sample was attained its peak stress, the shear wave velocity reduced and deviated from the previously existed trend line. This was probably caused by the non-uniformity induced by the formation of shear band. Subsequently, void ratios computed based on external measurements could not provide reasonable fitting to the initial stage of post-peak shear wave velocity. At very large strain levels after shear band formation, the digital images revealed that sample may internally re-arrange itself to be in a more uniform loose stage. This final stage void ratio estimated based on the proposed correlation derived during pre-peak state was close to the value of the maximum void ratio.

• Journal of Environmental Impact Assessment
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• v.23 no.3
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• pp.169-176
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• 2014

The purpose of this study is to estimate the vibration reduction effect of the borehole which is controlled the vibration propagation in the ground. For this study, we measured the vibration velocity before and after the borehole installation. The results are as follows: The peak particle velocity(PPV) and peak vector sum(PVS) was reduced by the borehole. And also, the deviation of vibration velocity before and after the borehole installation showed large values in longitudinal and vertical component depending on the receive distance, and increased depending on the size of vibration energy. Finally, the vibration isolation efficiency was 25~35 percentage at 1.5m receive distance, and was 4~14 percentage at 3.0m receive distance. It was found that the vibration isolation efficiency was good in small vibration energy, but was not good at long receive distance.

• Water Engineering Research
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• v.3 no.3
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• pp.163-176
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• 2002

In this study, laboratory experiments have been performed to investigate characteristics of the velocity fields and turbulence for non-buoyant plane jet in the vicinity of the jet nozzle using PIV system. The experimental results show that, in the transition region, the lateral velocity profile is in good agreement with Gaussian distribution. However, the coefficient of Gaussian distribution, $\K_{u,}$, decreases with longitudinal distance in the transition region. The existing theoretical equation for the centerline velocity tends to overestimate the measured data in the transition region. A new equation for the centerline velocity derived by incorporating varying $k_{u}$ gives better agreement with the measured data than the previous equation. The results of the turbulence characteristics show peak values are concentrated on the shear layers. The Reynolds shear stress profile shows the positive peak in the upper layer and negative peak in the lower layer. The turbulent kinetic energy also provides double peaks at the shear layers. The peak of the Reynolds shear stress and the turbulent kinetic energy increases until x/B=8, and then it decreases afterwards.s.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.87-94
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• 1999

The peak recoil force in a pistol have an effect on the reliability of the frame and target shooting. The experimental system has been established for measurement of the peak recoil force, which consists of force and velocity sensors, high speed camera. For effective operation of the system, a software has also developed, and combined with the hardwares. Several pistols have been tested and compared quantitatively on the peak recoil force and impact energy. It is concluded that the established system can be utilzed for checking peak force, and data accumulation for new pistol design.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.93-99
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• 2014

PURPOSE: The purpose of this study was to compare three dimensional displacement and peak velocity of the center of mass (COM) during obstacle crossing in young and older adults. METHODS: 10 young adults (6 males/4 females, $24.6{\pm}1.9$ years, age range: 22.0-26.9) and 10 older adults (1 male/9 females, $76.9{\pm}5.1$ years, age range: 65.2-81.2) participated in the study. Both groups crossed an obstacle, which is 10% of leg length, and COM was measured using motion analysis system. Independent t-test was used to find significant differences between two groups. RESULTS: The older adults showed significantly greater and faster COM displacement and peak velocity in mediolateral (M-L) direction as compared with young adults (p<.01 and p<.001 respectively). However, the young adults showed significantly greater and faster COM displacement and peak velocity in anteroposterior (A-P) direction as compared with older adults (p<.05 and p<.001 respectively). Furthermore, the young adults showed faster peak velocity of COM in vertical direction as compared with older adults (p<.001). However, no significant difference was found in the COM displacement in vertical direction between two groups. CONCLUSION: Greater and faster COM displacement and peak velocity in M-L direction in older adults were due to compensatory adjustment for appropriate contact on base of support of swing limb. Thus, the motion of the COM in M-L direction may be a crucial factor to identify risk of falls in older adults.