• Yonsei Medical Journal
• /
• v.59 no.9
• /
• pp.1115-1122
• /
• 2018

Purpose: To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. Materials and Methods: In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. Results: This study included 217 eyes of 118 participants (20-81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20-44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased CorvisIOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20-44 years, and over 44 years). Conclusion: We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.

• Journal of the Korean earth science society
• /
• v.23 no.8
• /
• pp.676-682
• /
• 2002

The concept of sensible temperature in winter is an attempt to quantify the sensation of cold by dry-bulb temperature combined with wind speed. Siple-Passel’s windchill equivalent temperature originated in experiments that are not conformable to various human conditions. Therefore, many investigators have found the flaws which are listed. Steadman’s model is based on the concept of thermal equilibrium and more sound and more representative of human conditions. But no classifications exist for Steadman’s windchill equivalent temperature, yet. The JAG/TI-model which was developed by US and Canada is more accurate, easy to understand and reflects human beings by conducting experiments using human volunteers but didn't take into account solar radiation, wet condition and physical state of the individual. Because of individual differences in people’s age, activity, health, metabolic rate, etc., no experimental evidence exists to suggest whether Siple-Passel’s, Steadman’s and JAG/TI-model’s windchill equivalent temperature is more applicable to the majority of people. Therefore we need the windchill model which is best applicable to Korean Army.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.2
• /
• pp.167-170
• /
• 2011

Purpose: This study was tried whether expectation of astigmatism from spherical equivalent visual acuity was possible. Methods: For 54 men and women (108 eyes) corrected to emmetropia, average age of 23.3, changes of visual acuity (5m) were measured with an increasing the powers at every ${\pm}$0.25D when the (-) axis of cross cylinder is $180^{\circ}$, $90^{\circ}$, and $45^{\circ}$, respectively. Results: As the power of cross cylinder was increased, visual acuity was decreased. When the powers of cross cylinder were ${\pm}$2.50D ($180^{\circ}$ and $90^{\circ}$) and ${\pm}$2.25D ($45^{\circ}$), visual acuity was 0.05 which is the minimum measurement possible. Conclusions: The diagram on astigmatism dealing with each spherical equivalent visual acuity was able to tabulate.

• Physical Therapy Rehabilitation Science
• /
• v.2 no.1
• /
• pp.12-20
• /
• 2013

Objective: To determine the energy consumed and muscle use during dance compared to different standard exercise devices. Design: Longitudinal study. Methods: Fifteen female subjects were evaluated to assess the energy cost and muscle activity during a 20 minute dance video compared to treadmill, elliptical track and bicycle ergometry. The later 3 forms of exercise were accomplished in four, 5 minute bouts at different intensities of exercise. Subjects were in the age range of 22-24 years old, were free of cardiovascular disease and did not have any neurological injuries. They were not sedentary and exercised at least twice a week. During the exercise, muscle activity was measured by the electromyogram recorded by surface electrodes on 6 muscle groups. A Cosmed metabolic cart was used to measure oxygen consumption during the exercise. Results: The aerobic dance video that was tested here was equivalent to a hard workout on any of the 3 exercise modalities. The dance routine was equivalent in terms of energy consumed to running at 225 watts of work or running for 20 minutes at a speed of 2 meters per second (4.47 miles per hour). Compared to the bicycle, it was equivalent to cycling at 112 watts for 20 minutes (2.25 kpm), and for the elliptical trainer, dance was equivalent to 435 watts. Concerning muscle use, the dance routine was the most balanced for upper, core and lower body muscles. Although the elliptical trainer was close, it required muscle less muscle use. Conclusion: A good dance video can be more effective than standard exercise equipment.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.1
• /
• pp.45-50
• /
• 2002

Use of a phenomenological model, developed far prediction of catalytic deactivation, is demonstrated in comparing harshness of different driving cycles that are currently used to rapidly age catalytic converters on engine test benches. The model shows that seemingly equivalent driving cycles cause the catalytic converters to reach significantly different levels of deactivation. The comparison of the model prediction with the limited vehicle data seems encouraging despite the simplicity of the model at the current stage of its infancy.

• Journal of Korean Neurosurgical Society
• /
• v.66 no.3
• /
• pp.239-246
• /
• 2023

Germinal matrix and intraventricular hemorrhage (GM-IVH) are the major causes of intracranial hemorrhage in premature infants. Cranial ultrasound (cUS) is the imaging modality of choice for diagnosing and classifying GM-IVH. Magnetic resonance imaging (MRI), usually performed at term-equivalent age, is more sensitive than cUS in identifying hemorrhage in the brain. Post-hemorrhagic ventricular dilatation is a significant complication of GM-IVH and correlates with adverse neurodevelopmental outcomes. In this review, we discuss the various imaging findings of GM-IVH in premature infants, focusing on the role of cUS and MRI.

• Journal of Korean Academy of Nursing
• /
• v.35 no.2
• /
• pp.390-398
• /
• 2005

Purpose: This study was aimed at providing basic data for developing a nursing intervention program which enables systematic and correct visual acuity care by discovering out visual acuity conditions, prevalence rate of myopia, and the factors related to myopia with Preschool children. Method: The subjects of this study consisted of 519 children between 3 and 6 years of age from 12 kindergartens in Seoul which were selected through multiple cluster sampling. Myopia was defined as the spherical equivalent (SE) of more than -0.5 diopters (D) in the right eye. The data was analyzed by t-test, 2-test, ANOVA, and logistic regression by using the SAS program. Result: The prevalence rate of myopia was $8.7\%$. the odds ratio of child myopia when one parent had myopia was 2.2 times higher than when neither parent had myopia. The odds ratio of child myopia when reading more than three books per week was 0.27 times higher than reading less than three books. Conclusion: Myopia should be continuously and intensively managed from the age of 3.

• IE interfaces
• /
• v.24 no.3
• /
• pp.173-186
• /
• 2011

In this paper, we evaluate life annuity plans for Korean pre-retired single and married couple participating Korea National Pension (KNP) and find optimal life annuity strategy by using utility-based measurements called AEW (Annuity Equivalent Wealth). Specifically, we extend a previous study to obtain a detailed optimal combination of annuitizing age and wealth in terms of percentage of net wealth at the time of retirement. A nonlinear optimization model is formulated with the objective of maximizing utility on consumption and bequest, and the dynamic programming (DP) technique is used to solve this problem. We find that there exist consistent patterns in optimal combinations of annuitizing age and wealth. Also, for all cases the optimal combination is significantly better than several other combinations. The results indicate that using the optimal approach can be beneficial to practitioners in insurance industry and prospective purchasers of life annuity. We conclude the paper with some discussions and suggestions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.4 no.4
• /
• pp.253-262
• /
• 1992

A numerical procedure is introduced to calculate local ventilation effectiveness using the definitions of local decay rate and local mean age. A low Reynolds number $k-{\varepsilon}$ model is implemented to calculate steady state turbulent velocity distributions, and a step-down method is used to calculate transient concentration distributions. Simulations are carried out for several different values of air change rates and several different diffuser angles in a two-dimensional model of a half scale office room. The results show that the local ventilation effectiveness within a room could vary significantly from one location to another. The nominal air change rate based on the assumption of complete mixing of room air does not provide the local ventilation effectiveness information. It is numerically proved that the local mean age distribution obtained from the transient calculation is equivalent to the steady state concentration distribution with homogeneously distributed contaminant sources.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.237-242
• /
• 2003

The object of this study is to investigate the strength development properties and the strength prediction of three-component concrete using the fly ash and the blast-furnace slag by a maturity method. The results were as follows. The values of the activation energy on this experiment are calculated as 38.69, 36.47, 32.46, 30.99 KJ/mol in the W/B 60, 55, 50, 45%. And it is considered that the equivalent age can be used to predict strength of the three-component concrete in the optional age. Also the strength of the three-component concrete can be predicted from the result of high correlation between predicted strength and measured strength.