• Journal of Welding and Joining
• /
• v.10 no.3
• /
• pp.54-62
• /
• 1992

Large steel water pipes are joined prevalently by bell and method and welded at inside and outside of lapped parts. According to the Korean Standard(KS) for fabrication of water pipes, the weldments are designed to have the length of leg which is same as or larger than the thickness of the pipe. It is recently pointed out that the standard size of weldments is too large, which results in an excessive consumption of material and labor. In this study, several cases of weldments having different sizes were investigated to reduce the length of leg to the effective size. For each case, the analysis of stresses was carried out to evaluate the safety of the welded pipes by using a package program, ANSYS, under the consideration of the loading condition of water pipes which includes the soil pressure on the pipe, the load over the road, and temperature change of the pipe. The results of this study revealed that the weldment which has the length of leg of the size over 0.7*thickness of the pipe could provide a stress level below the yield strength. Especially when the length of leg is 85% of the wall thickness, the maximum equivalent stress is only slightly higher than that of the leg of fillet of the size of 1.0*pipe thickness.

• Advances in concrete construction
• /
• v.15 no.2
• /
• pp.115-126
• /
• 2023

This paper investigates creep analysis of a plate made of Al-SiC functionally graded material using Mendelson's method of successive elastic solution. All mechanical and thermal material properties, except Poisson's ratio, are assumed to be variable along the thickness direction based on the volume fraction of reinforcement and thickness. First, the basic relations of the plate are derived using the Love-Kirchhoff plate theory. The solution of governing equations yields an elastic solution to start creep analysis. The creep behavior is demonstrated through Norton's equation based on Pandey's experimental results extracted for Al-SiC functionally graded material. A linear variation is assumed for temperature distribution along the thickness direction. The creep strain, as well as the thermal strain, are included in the governing equations derived from classical plate theory for mechanical strain. A successive elastic solution based on Mendelson's method is employed to derive the history of stresses, strains, and displacements over a long time. History of stresses and deformations are obtained over a long time to predict damage to the plate because of various loadings, and material composition along the thickness and planar directions.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.11
• /
• pp.52-62
• /
• 1995

In the laser surface hardening process the geometrical parameters, especially the depth, of the hardened layer are utilized to assess the integrity of the hardening layer quality. Monitoring of this geometrical parameter ofr on-line process control as well as for on-line quality evaluation, however, is an extremely difficult problem because the hardening layer is formed beneath a material surface. Moreover, the uncertainties in monitoring the depth can be raised by the inevitable use of a surface coating to enhance the processing efficiency and the insufficient knowledge on the effects of coating materials and its thicknesses. The paper describes the extimation results using neural network to estimate the hardening layer depth from measured surface temperanture and process variables (laser beam power and feeding velocity) under various situations. To evaluate the effec- tiveness of the measured temperature in estimating the harding layer depth, estimation was performed with or without temperature informations. Also to investigate the effects of coating thickness variations in the real industry situations, in which the coating thickness cannot be controlled uniform with good precision, estimation was done over only uniformly coated specimen or various thickness-coated specimens. A series of hardening experiments were performed to find the relationships between the hardening layer depth, temperature and process variables. The estimation results show the temperature informations greatly improve the estimation accuracy over various thickness-coated specimens.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.108-111
• /
• 2001

YBCO HTS thick films coated using powder, Y$_2$O$_3$+L, quenched over 1200$^{\circ}C$ was studied. Quenched powder was crushed and mixed well in order to obtain uniformly dispersed Y2ll. Also, the powder was prepared with various condition in other to acquire optimum micro structure. As a result, it was found that the quenched sample on 1300$^{\circ}C$, holding time of 30min, has a bettor characteristic than other sample. On the other hand, the effect of film thickness was investigated. We concluded that the initiate film thickness has to be over 150$\mu\textrm{m}$. Especially, it was found that the film coated over 3 times with 50$\mu\textrm{m}$ m was best quality.

• Journal of Korean Clinical Health Science
• /
• v.5 no.4
• /
• pp.1021-1025
• /
• 2017

Purpose: Changes in corneal thickness after wearing hydrogel lens and silicone-hydrogel lens with different oxygen transmission rates wew syudied. Methods: Experiments were performed on 11 subjects(22 eyes). corneal thickness was measured after wearing contact lenses for 8 hours. Corneal thickness was measured using ORB Scan II(ver. 3.14) Results: In the results of the corneal thickness measurement by direction, in the case of the hydrogel-tor lens, the center thickness was $33.63{\mu}m$, the nasal was $34.29{\mu}m$, the temporal was $27.17{\mu}m$, the inferior was $27.17{\mu}m$, the superior was $18.90{\mu}m$, and change rates were 6.28%, 5.71%, 5.40%, 4.75% and 3.09%, respectively. In the results of the corneal thickness measurement by diameter, in the case of the hydrogel-tor lens, the center was $33.63{\mu}m$, the mid-peripheral was $28.19{\mu}m$, the peripheral was $24.18{\mu}m$, and change rates were 6.28%, 4.76%, and 3.79%, respectively. Conclusions: The hydrogel lenses with relatively low oxygen transmission rates resulted in a significant increase in thickness over the entire cornea compared to silicon-hydrogel lenses with high oxygen transmission rates.

• Tribology and Lubricants
• /
• v.11 no.5
• /
• pp.71-77
• /
• 1995

The capacitance technique was used to measure the minimum oil film thickness in engine bearing and the central oil film thickness between cam and tappet. This method is based on the measurement of total capacitance of oil film. For the measurement of the oil film thickness between cam and tappet, two surfaces were assumed to be flat and parallel within the Hertzian region and all the measured capacitance originated from this region. Shear rates from the measured minimum oil film thickness are over 10$^{6}$ sec$^{-1}$ in the greater part in both two cases. The minimum oil film thickness in engine bearing is larger than the surface roughness. Between cam and tappet it is mostly smaller than the surface roughness. In spite of the awkward restriction of the reliability of measured oil film thickness, it was known that the capacitance technique makes it possible to measure the oil film thickness in elastohydrodynamic and mixed lubrication regimes as well as in hydrodynamic regime. Therefore, it is also possible to classify the lubrication regimes based on the oil film thickness.

• Korean Journal of Health Education and Promotion
• /
• v.12 no.2
• /
• pp.62-72
• /
• 1995

We studied the effects of behavior modification and aerobic exercise on body weight, degree of obesity, % body fat, triceps skinfold thickness, blood pressure and eating behavior among overweight middle school girls. 15 girls participated in the behavior modification program by joining 60-90 minute group session weekly. The aerobic exercise program was given to 13 girls 3 times per week with 60 minutes each time. The data were obtained before treatment, after 4 and 8 weeks after treatment. In analyzing the data, repeated measures ANOVA were adopted. The results were as follows ; 1. For the changes of body weight between 2 groups, body weight of behavior modification groups decreased significantly than these of aerobic exercise group at 4 and 8 weeks after treatment, 2. For the changes of degree of obesity between 2 groups, there were no significant differences over time, 3. The analysis of change of % body fat did not reveal significant differences between 2 groups over time, 4. The changes of triceps skinfold thickness were significant differences between 2 groups over time, 5. For the changes of systolic blood pressure between 2 groups, there were significant differences over time. At 4 weeks after treatment, systolic blood pressure of behavior modification group decreased significantly than these of aerobic exercise group. 6. The changes of diastolic blood pressure were significant differences between 2 groups over time.

• Journal of Sasang Constitutional Medicine
• /
• v.23 no.2
• /
• pp.218-229
• /
• 2011

1. Objectives: This study is to investigate the relationship between Intima Media Thickness(IMT) of common carotid artery and Sasang Constitution. 2. Methods: 839 persons, over 40 years old, participated in community-based cohort of Korea Genome and Epiedemiology Study (KOGES) in Wonju City and Pyeongchang City of South Korea from June 2006 to February 2008. The diagnosis of Common carotid Intima Media Thickness was evaluated by B Mode ultrasonography, cardiovascular risk factors were checked using questionnaire and blood samples. Constitution was verified by a Sasang constitution specialist according to the results of PSSC(Phonetic System for Sasang Constitution), facial photos and a simplified Sasang constitutional questionnaire. Multiple regression analysis and logistic regression analysis were performed with SPSS. 3. Results: There were significantly high values in waist circumference, fasting blood sugar, systolic blood pressure, diastolic blood pressure, triglyceride, HOMA-IR and hsCRP in Taeeumin and low in HDL-cholesterol and adiponectin in Taeeumin. There were significantly high value in Common Carotid Intima Media Thickness in Taeeumin. Age was the significant cardiovascular risk factor irrespective of Sasang constitution in all participants. There was a positive correlation between smoking and Soyangin in all participants and men. There were positive correlations between LDL-cholesterol, BMI and Taeeumin in all participants and men. There were positive correlations between hsCRP and Soeumin in all participants and men. There was significantly high odds ratio of Taeeumin over Soeumin in common carotid Intima Media Thickness. 4. Conclusions: Regimens on cardiovascular diseases should be considered according to Sasang constitution. There are more sensitive risk factor in each constitution; smoking in Soyangin, LDL-cholesterol and BMI in Taeeumin, hsCRP in Soeumin.

• Archives of Plastic Surgery
• /
• v.45 no.1
• /
• pp.45-50
• /
• 2018

Background Free muscle flaps are a mainstay for reconstruction of distal third leg wounds and for large lower extremity wounds with exposed bone. However a major problem is the significant postoperative flap swelling, which may take months to resolve. We studied the efficacy and safety of immediate application of a vacuum assisted closure (VAC) dressing after a free muscle flap to the lower extremity. Methods Over a 19 months period, all consecutive free muscle flaps for lower extremity reconstruction at a Level I trauma center were evaluated prospectively for postoperative flap thickness, complications and flap survival. Immediate application of a VAC dressing was performed in 9 patients, while the flap was left exposed for monitoring in 8 patients. Results There was no statistically significant difference in flap survival between both cohorts. Mean flap thickness at postoperative day 5 for the VAC group was $6.4{\pm}6.4mm$, while flap thickness for the exposed flap group was $29.6{\pm}13.5mm$. Flap thickness was significantly decreased at postoperative day 5 for the VAC dressing group. Conclusions Immediate application of VAC dressing following free muscle flaps to the lower extremity does not compromise flap survival or outcomes and results in decreased flap thickness and a better aesthetic outcome.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.267-274
• /
• 2004

Since there is a large variation in measurements of the thickness of corroded elements, the thickness of corroded elements are considered as imprecise elements. There is also a considerable degree of uncertainty in a visual assessment of thickness loss. The remaining thickness of a severly corroded element may be represented by an imprecise which expresses the range over which there is uncertainty about the thickness. Therefore, the objective of this paper is to propose a new methodology to safety assessment using imprecise reliability into conventional safety assessment frameworks. For this purpose, this study presents a safety assessment model using Imprecise reliability for large civil structures and demonstrates the applicability of the approach to cable-stayed bridge projects.