• Journal of Drive and Control
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• v.17 no.2
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• pp.28-37
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• 2020

It is difficult to analytically derive the relationship among volumetric displacement, flowrate, torque, and rotation speed regarding an instantaneous position of gerotor hydraulic pumps/motors. This can be explained by the geometric shape of the rotors, which is highly complicated. Herein, an analytical method for the instantaneous torque, rotation speed, flowrate, and volumetric displacement of a pump/motor is proposed. The method is based on two physical concepts: energy conservation and torque equilibrium. The instantaneous torque of a pump/motor shaft is determined for the posture of rotors from the torque equilibrium. If the torque equilibrium is combined with the energy conservation between the hydraulic energy of the pump/motor and the mechanical input/output energy, the formula for determining the instantaneous volumetric displacement and flowrate is derived. The numerical values of the instantaneous volumetric displacement, torque, rotation speed, and flowrate are calculated via the MATLAB software programs, and they are illustrated for the case in which inner and outer rotors rotate with respect to fixed axes. The degrees of torque fluctuation, speed fluctuation, and flowrate fluctuation can be observed from their instantaneous values. The proposed formula may provide a better understanding of the design or analysis process of gerotor pumps/motors.

• Smart Structures and Systems
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• v.20 no.3
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• pp.303-309
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• 2017

Structural control through seismic isolation using elastomeric rubber bearing, which is also known as High Damping Rubber Bearing (HDRB), has seen an increase in use to provide protective from earthquake, especially for new buildings in earthquake zones. Besides, HDRB has also been used in structural rehabilitation of older yet significant buildings, such as museums and palaces. However, the present design approach applied in normal practice has often resulted in dissimilar HDRB dimension requirement between structural designers and bearing manufacturers mainly due to ineffective communication. Therefore, in order to ease the design process, most HDRB manufacturers have come up with catalogs that list all necessary and relevant product lines specifically for structural engineers to choose from. In fact, these catalogs contain physical dimension, compression property, shear characteristic, and most importantly, the total rubber thickness. Nonetheless, other complicated issues, such as the relationship between target isolation period and displacement demand (which determines the total rubber thickness), are omitted due to cul-de-sac fixing of these values in the catalogs. As such, this paper presents a formula, which is derived and extended from the present design approach, in order to offer a simple guideline for engineers to estimate the required HDRB size. This improved design formula successfully minimizes the discrepancies stumbled upon among structural designers, builders, and rubber bearing manufacturers in terms of variation order issue at the designing stage because manufacturer of isolator is always the last to be appointed in most projects.

• Korean Journal of Community Nutrition
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• v.7 no.3
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• pp.345-353
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• 2002

A survey was carried out to investigate the breastfeeding knowledge, breastfeeding rates ultra related factors among women in Seoul and the Chungbuk area, in order to obtain baseline data for the development of an education program on breastfeeding. Subjects included 671 lactating mothers who visited public health or pediatric centers, between December, 1999 and February, 2000 and were interviewed using a questionnaire. The results are as follows: In the breastfeeding knowledge, most of the subjects (93.4%) know correctly that 'breastfeeding is better for a baby's emotional development than formula feeding,'whereas only half of the subjects (51.7%) answered correctly the question on whether 'formula is more nutritious than breastmilk.'The breastfeeding rates were about 57%, 40%, 33% and 12%, respectively for baby's aged 1, 3, 6, and 12 months. These results showed that the breastfeeding rate rapidly decreased with the baby's age. Lower breastfeeding rates were associated with high educational level (college graduate and above), high income, mothers'employment, no experience of attending breastfeeding education programs, and no planning on breastfeeding prior to pregnancy. There was a significant relationship between the level of knowledge and breastfeeding practice; the higher the knowledge score, the higher the breastfeeding rate. In conclusion, an education program should be developed and offered for each low breastfeeding rate group, in order to promote breastfeeding.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.197-217
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• 2012

Detailed analysis of internal forces of exterior beam-column joints of RC frames under seismic action is reported in this paper. A formula is derived for calculating the average joint shear from the column shears, and a formula is proposed to estimate torque in eccentric joints induced by seismic action. Average joint shear stress and strain are defined consistently for exterior joints, which can be used to establish joint shear constitutive relationship. Numerical results of shear, bending moment and torque in joints induced by seismic action are presented for a pair of concentric and eccentric exterior connections extracted from a seismically designed RC frame, and two sections located at the levels of beam bottom and top reinforcement, respectively, are identified as the critical joint sections for evaluating seismic joint behavior. A simplified analysis of the effects of joint shear and torque on the flexural strengths of the critical joint sections is made for the two connections extracted from the frame, and the results indicate that joint shear and torque induced by a strong earthquake may lead to "joint-hinging" mechanism of seismically designed RC frames.

• Smart Structures and Systems
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• v.14 no.3
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• pp.397-418
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• 2014

In this paper, a simple two-step method for structural vibration-based health monitoring for beam-like structures have been extended to plate-like structures with though-thickness cracks. Crack locations and severities of plate-like structures are detected using a hybrid approach. The interval wavelet transform is employed to extract crack singularity locations from mode shape and support vector regression (SVR) is applied to predict crack serviettes form crack severity detection database (the relationship of natural frequencies and crack serviettes) using several natural frequencies as inputs. Of particular interest is the natural frequencies estimation for cracked plate-like structures using Rayleigh quotient. Only the natural frequencies and mode shapes of intact structures are needed to calculate the natural frequencies of cracked plate-like structures using a simple formula. The crack severity detection database can be easily obtained with this formula. The hybrid method is investigated using numerical simulation and its validity of the usage of interval wavelet transform and SVR are addressed.

• Child Health Nursing Research
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• v.26 no.1
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• pp.90-97
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• 2020

Purpose: The purpose of this study was to investigate the effects of a breastfeeding support program (BSP) on the prevalence of exclusive breastfeeding and growth in late-preterm infants. Methods: A quasi-experimental study was conducted. The participants were 40 late preterm infants (LPIs), of whom 20 were assigned to the experimental group and 20 to the control group. For the mothers in the experimental group, a BSP was provided prior to the LPIs' discharge and reinforced once a week for 4 weeks. Information on the feeding type was collected by observation and the LPIs' body weight was measured. Results: There were significant differences in feeding type by group and time. Exclusive breastfeeding was 5.18 times more common in the experimental group than in the control group (odds ratio=5.18, 95% confidence interval=1.11~16.70). However, weekly weight gain did not show a significant relationship with group and time (F=0.40, p=.712). Conclusion: The BSP was helpful for increasing the rate of exclusive breastfeeding in LPIs. Furthermore, the LPIs in the experimental group, which had a higher likelihood of being exclusively breastfed, showed an equivalent amount of weight gain as the LPIs in the control group, in which infants were more likely to be formula-fed.

• Atmosphere
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• v.18 no.1
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• pp.15-23
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• 2008

KMA (Korea Meteorological Society) and RSMC (Regional Specialized Meteorological Center) Tokyo - Typhoon Center isue 15/30 m/s radii in the TC (tropical cyclone) advisory for the information on the TC size. Meanwhile, JTWC Beaufort wind force scale, 34 kt and 64 kt correspond to the 'gale' and 'hurricane'. A ned to identify the range of the gale/hurricane wind from the TC bulletin of RSMC Tokyo or KMA that contains only 15/30 m/s radi motivates this study. An algorithm for estimating the radius of gale/huricane wind is developed by utilizing Holland's empirical formula on TC's wind-pressure relationship.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.3
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• pp.213-221
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• 2005

In order to get more accurate GPS position with the changes of the inner configuration setting of GPS receiver, the authors carried out measurements of the position at known it with one antenna and two GPS receivers manufactured by same company. We have investigated the accuracies of positions according to the change of the maskangle and receiving mode of output data in inner configuration of GPS receivers, and analyzed the relationships between numbers of satellites visibility and maskangles, and values of HDOP and maskangles. When the maskangles in inner configuration were set below 20 degree, the accuracies of positions were high. But if they were became bigger than 25 degree, standard deviations ot position errors and HDOPS of positions were became bigger. Numbers of satellites visibility(y) and maskangles(x) have relations with a formula, y = -0.1662x+9.9225, and values of HDOP(y) and maskangles(x) have relations with a formula, y = 0.6035 $e^{0.0517x}$. The results of position accuracies observed by two GPS receivers to the known position at same time were that average errors of position fixs by GPS receiver configured with NMEA0183 mode were 6.7m and standard deviations were 1.5m, and them by GPS receiver configured with binary mode were 5.0m and standard deviations were 1.1m respectively.

• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.153-159
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• 2003

When available rainfall data is not sufficient, a rough tendency of I-D-F relationship appeared frequently. In fact, rainfall intensity on the curve shows abnormally higher value the longer rainfall duration is applied that gives rise to great confusion to apply a rainfall I-D-F relationships curve to a practical work, however, the research work will present a way to solve above mentioned problem by the use of the Box-Cox transformation formula for a given rainfall data. The study came to a conclusion that the Box-Cox transformation formula is satisfied to utilize in a practical work on the ground of analysis for rainfall data of Sancheong and Yeongcheon.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.343-352
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• 2019

For quality control and the economical design of grouted sand, the prior establishment of the unconfined compressive strength (UCS) estimating formula is very important. This study aims to develop an empirical UCS estimating formula for grouted sand based on the physical properties of sands and the UCS of cured pure grout. Four sands with varying particle sizes were grouted with both microfine cement and Ordinary Portland cement. Grouted specimens were prepared at three different relative densities and at three different water-to-cement ratios, and unconfined compression tests were performed. The results demonstrate that UCS of grouted sand can be expressed as the power function of the UCS of cured pure grout: $UCS_{grouted\;sand}/1MPa=A_{soil}{\cdot}(UCS_{pure}/1MPa)^N$. Because the exponent N strongly depends on the combination of pore area and pore size, N is expressed as the function of porosity (n) and specific surface ($S_a$). Additionally, because $S_a$ determines the area of the sand particle that cement particles can adsorb and n determines the number of cementation bondings between sand particles, $A_{soil}$ is also expressed as the function of n and $S_a$. Finally, the direct relationship between $A_{soil}$ and N is also investigated.