• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1314-1319
• /
• 2008

Fatigue reliability problems are nowadays actively considered in the design of mechanical components. Recently, Dimension Reduction Method using Kriging approximation (KDRM) was proposed by the authors to efficiently calculate statistical moments of the response function. This method, which is more tractable for its sensitivity-free nature and providing the response PDF in a few number of analyses, is adopted in this study for the reliability analysis. Before applying this method to the practical fatigue problems, accuracies are studied in terms of parameters of the KDRM through a number of numerical examples, from which best set of parameters are suggested. In the fatigue reliability problems, good number of experimental data are necessary to get the statistical distribution of the S-N parameters. The information, however, are not always available due to the limited expense and time. In this case, a family of curves with prediction interval, called P-S-N curve, is constructed from regression analysis. Using the KDRM, once a set of responses are available at the sample points at the mean, all the reliability analyses for each P-S-N curve can be efficiently studied without additional response evaluations. The method is applied to a spring design problem as an illustration of practical applications, in which reliability-based design optimization (RBDO) is conducted by employing stochastic response surface method which includes probabilistic constraints in itself. Resulting information is of great practical value and will be very helpful for making trade-off decision during the fatigue design.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.8 no.6
• /
• pp.483-490
• /
• 2015

There are many software reliability models that are based on the times of occurrences of errors in the debugging of software. It is shown that it is possible to do likelihood inference for software reliability models based on finite failure model and non-homogeneous Poisson Processes (NHPP). For someone making a decision about when to market software, the conditional failure rate is an important variables. The infinite failure model are used in a wide variety of practical situations. Their use in characterization problems, detection of outlier, linear estimation, study of system reliability, life-testing, survival analysis, data compression and many other fields can be seen from the many study. Statistical process control (SPC) can monitor the forecasting of software failure and thereby contribute significantly to the improvement of software reliability. Control charts are widely used for software process control in the software industry. In this paper, proposed a control mechanism based on NHPP using mean value function of Musa-Okumo and Power law type property.

• Journal of Korean Traditional Oncology
• /
• v.27 no.1
• /
• pp.25-36
• /
• 2022

The Randomized Control Trial (RCT) is the most well-established and widely used statistical methodology in clinical research; however, applying thorough RCT to cancer patients presents challenges such as ethical concerns, high costs, short clinical periods, and limitations in collecting various side effects. To address this issue, the propensity score matching method, which takes advantage of the benefits of observational research while compensating for the drawbacks of randomized control trials, is used in a variety of fields. In recent years, 28 studies on the effectiveness of Korean medicine on tumors have been conducted abroad using the Propensity Score Matching Method, but none have been conducted in Korea. The majority of studies have focused on liver cancer, colon cancer, lung cancer, and stomach cancer, with endpoints such as survival time, incidence rate, quality of life, and treatment outcomes revealing statistical differences in how Korean medicine intervention affects treatment outcomes. As a result, well-established studies using the propensity matching score methodology should be useful in evaluating the impact of Korean medicine in oncology treatments.

• Journal of Korean Foot and Ankle Society
• /
• v.27 no.1
• /
• pp.12-16
• /
• 2023

Purpose: Postoperative exercise for acute Achilles tendon rupture is important for a patient's return to daily life and sports. On the other hand, the protocol requires considerable effort to educate patients and continuous checking. This study evaluated the outcome of a new simple and delayed rehabilitation protocol after Achilles tendon rupture repair. Materials and Methods: From July 2014 to November 2020, one hundred eighty-three patients were operated on by one surgeon. The exercise protocol was classified into two methods. One group (immediate protocol, control group) started immediate full weight bearing with a 20° plantar flexion range of motion from two days postoperatively. Ankle dorsiflexion was restricted to 0°. The other group (delayed protocol, case group) started full weight bearing with a controlled ankle motion boot from two weeks postoperatively. No range of motion exercise was allowed until six weeks postoperatively. Age, sex, body mass index, ankle range of motion, muscle power, time to return to previous physical activity, functional score, and complication rate were evaluated. The results of the two groups were compared using a Mann-Whitney test. Statistical significance was set as p<0.05. Results: The range of motion, double heel rising, and one-leg standing were achieved faster in the control group (p<0.05). However, single-heel rising, repeated single-heel rising, return to previous activity (work, run, and sport), and functional scores showed no statistical difference (p>0.05). Conclusion: Simple and delayed postoperative rehabilitation of acute Achilles tendon rupture without active range of motion exercises showed satisfactory functional results and a low complication rate.

• The Journal of Korean society of community based occupational therapy
• /
• v.9 no.1
• /
• pp.57-67
• /
• 2019

Objective : This study aimed to identify types of leisure time spending of the Korean elderly according to the data of Hours of Living 2014 from National Statistical Office, and compare and analyze features of leisure time spending based on general characteristics of the elderly. Method : This study has only adopted the data of 9228 elder people whose ages were above 65, and their general characteristics and time spending features form the data of Hours of Living 2014. The final comparison and analysis has been made through behavior classification (1 major classification, 7 medium classification, 39 minor classification), which reflects how the elderly spend their leisure time according to their household and personal characteristics. Result : Firstly, the Korean elderly were found to spend most of their leisure time with media. Secondly, analyzing the features of leisure time spending based on household characteristics of the elderly, their gender and household income showed significant differences in all types of leisure time activities except for cultural and sightseeing activity. And their marital status showed significant differences in most of the leisure time activities excluding leisure time activity with media and cultural and sightseeing activity. Thirdly, analyzing the features of leisure time spending based on personal characteristics of the elderly, their education level has made significant differences in all types of leisure time activities. As for their economic activity status and average monthly income, they showed meaningful differences in most of the leisure time activities excluding cultural and sightseeing activity and ritual activity. Conclusion : We should help to find meaningful occupation within personal contexts and arrange it properly with balanced leisure time spending. Moreover, it is highly important to have appropriate occupational approach to prevent social isolation of the Korean elderly, and ensure their fruitful and successful later life.

• 재활복지
• /
• v.20 no.4
• /
• pp.283-299
• /
• 2016

The purpose of this study was to investigate the effect of dysphagia intervention function and life quality of stroke patients. each 5 patients were randomly assigned in two groups, control group performing indirect feeding and experimental group performing direct feeding. Evaluation of the swallowing function was performed before intervention, after 4weeks and 8 weeks using CDS, PAS with VFSS and quality of life was performed twice, before and after intervention. Two groups showed the improved swallowing function, control group showed the significant difference only in CDS(p<.05). but experimental group showed the significant differenc in CDS and PAS(p<.01). both groups showed the significant improvement in quality of life(p<.05). but in comparison between group, no significant statistical difference were found(p>.05). Therefore, this study showed that both the swallowing function and quality of life were improved as time passed, but swallowing function was much more improved in experimental group.

• Journal of Trauma and Injury
• /
• v.29 no.1
• /
• pp.8-13
• /
• 2016

Purpose: Specialized general trauma surgeons play an important role in the care of trauma patients. Hemoperitoneum is a severe, but representative, condition following a life-threatened trauma. The objective of this study was to compare the outcomes for polytrauma patients with hemoperitoneum between the periods during which a trauma surgeon was available and that unavailable. Methods: Thirty-one trauma patients with hemoperitoneum who were treated at Korea University Guro Hospital over a period of 4 years were included in this study, and their case records were analyzed retrospectively. The patients were divided into two groups, the 2011 and 2012 group and the 2013 and 2014 group corresponding, respectively, to the periods that a trauma surgeon was not and was working. Vital signs on admission, scores on the injury severity scale and, Glasgow coma scale, elapsed time to diagnostic, and therapeutic, and/or operative interventions were studied. The effects on intensive care unit and hospital lengths of stay, as well as mortality, were also studied. Results: The study population consisted of 16 and 15 patients in group 1 and 2, respectively. The patients in both groups had six unstable hemodynamic on admission. The time to the main procedure (intervention, operation etc.) was longer during the periods when a trauma surgeon was not working than it was during the period when working. This difference did not reached statistical significance. The mortality rates for the two groups were not statistically different either (18.75% vs 26.67%; p=0.928). Conclusion: Having at least one specialized general trauma surgeon on duty may reduce the time to intervention and surgery for severe trauma patients with hemoperitoneum, but appears to have no effect on the mortality rates. In conclusion, having only one trauma surgeon on duty does not improve the quality of care for trauma patients.

• Child Health Nursing Research
• /
• v.22 no.4
• /
• pp.379-389
• /
• 2016

Purpose: A longitudinal study was conducted to explore flora colonization and oral glucose high-risk newborns during the first 7 days after birth. Methods: Oral secretions of hospitalized newborns were obtained for microbial cultures and glucose test at days 1-7 after birth. Results: Among the total 112 newborns, 40% were girls and 73% were premature. Mean gestational age was $34.4{\pm}3.2$ weeks and weight was $2,266{\pm}697.5$ grams. The most common flora included Streptococcus (28.2%), Methicillin-resistant Staphylococcus aureus (MRSA, 10.9%), Staphylococcus (6.0%) and Coagulase-Negative Staphylococcus (CNS, 4.0%). The average oral glucose level was $29.2{\pm}23.0mg/dL{\sim}58.2{\pm}39.5mg/dL$. Newborns with higher oral glucose than serum (crude odds ratio [ORc] =1.75; 95% confidence interval [CI] =1.03-2.97), phototherapy (ORc=3.30; 95% CI=2.29-4.76) and prone position (ORc= 2.04; 95% CI=1.13-3.69) were more likely to be colonized. Having oral tubes (ORc=0.42; 95% CI=0.29-0.59), parental nutrition (ORc=0.21; 95% CI=0.13-0.32) and antibiotics (ORc=0.51; 95% CI=0.36-0.73) had protective effects. For oral glucose statistical significances existed on time effect among newborns with Streptococcus (F=9.78, p=.024), MRSA (F=7.60, p=.037) or CNS (F=11.15, p=.019) and interaction between time and colonization among newborns with all of four flora (F=2.73, p=.029) or colonization with only Staphylococcus (F=2.91, p=.034). Conclusion: High-risk newborns develop flora colonization at an early period of life. Their clinical features were associated with types and time of oral flora colonization. They need close monitoring and multifaceted intervention to improve oral environment and infection control.

• Computers and Concrete
• /
• v.2 no.4
• /
• pp.325-343
• /
• 2005

Chloride ingress is a common cause of deterioration of reinforced concrete located in coastal zone. Modeling the chloride ingress is an important basis for designing reinforced concrete structures and for assessing the reliability of an existing structure. The modeling is also needed for predicting the deterioration of a reinforced structure. The existing deterministic solution for prediction model of corrosion initiation cannot reflect uncertainties which input variables have. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. There are a lot of prediction model for predicting the time of reinforcement corrosion of structures exposed to chloride-induced corrosion environment. In this work, RILEM model formula and Crank's solution of Fick's second law of diffusion is used. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters instead of random variables of probabilistic modeling of Monte Carlo Simulation and the fuzziness of the time to corrosion initiation is determined by the fuzzy arithmetic of interval arithmetic and extension principle. An analysis is implemented by comparing deterministic calculation with fuzzy arithmetic for above two prediction models.

• The Korean Journal of Physiology and Pharmacology
• /
• v.7 no.1
• /
• pp.15-23
• /
• 2003

Cellular redox state is known to be perturbed during ischemia and that $Ca^{2+}$ and $K^2$ channels have been shown to have functional thiol groups. In this study, the properties of thiol redox modulation of the ATP-sensitive $K^2$ ($K_{ATP}$) channel were examined in rabbit ventricular myocytes. Rabbit ventricular myocytes were isolated using a Langendorff column for coronary perfusion and collagenase. Single-channel currents were measured in excised membrane patch configuration of patch-clamp technique. The thiol oxidizing agent 5,5'-dithio-bis-(2-nitro-benzoic acid) (DTNB) inhibited the channel activity, and the inhibitory effect of DTNB was reversed by dithiothreitol (disulfide reducing agent; DTT). DTT itself did not have any effect on the channel activity. However, in the patches excised from the metabolically compromised cells, DTT increased the channel activity. DTT had no effect on the inhibitory action by ATP, showing that thiol oxidation was not involved in the blocking mechanism of ATP. There were no statistical difference in the single channel conductance for the oxidized and reduced states of the channel. Analysis of the open and closed time distributions showed that DTNB had no effect on open and closed time distributions shorter than 4 ms. On the other hand, DTNB decreased the life time of bursts and increased the interburst interval. N-ethylmaleimide (NEM), a substance that reacts with thiol groups of cystein residues in proteins, induced irreversible closure of the channel. The thiol oxidizing agents (DTNB, NEM) inhibited of the $K_{ATP}$ channel only, when added to the cytoplasmic side. The results suggested that metabolism-induced changes in the thiol redox can also modulate $K_{ATP}$ channel activity and that a modulatory site of thiol redox may be located on the cytoplasmic side of the $K_{ATP}$ channel in rabbit ventricular myocytes.