• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.234-242
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• 1999

In this paper, a method for assessment of the anisotropic machined surfaces is proposed. Fractal dimension (FD) is calculated using structure function and an index of the anisotropy is obtained as a ratio of its maximum and minimum value. The upper limit of fractal region on the structure function is determined as the length of the lag where the autocorrelation function shows 20% of its maximum value. The model of the structure function is derived from that of the auto correlation function. And, it shows that the new method and the proposed index of anisotropy are useful.

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.175-189
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• 2012

This paper presents an algorithm for structural reliability with the response surface method. For this aim, an approach with three stages is proposed named as improved response surface method. In the algorithm, firstly, a quadratic approximate function is formed and design point is determined with First Order Reliability Method. Secondly, a point close to the exact limit state function is searched using the design point. Lastly, vector projected method is used to generate the sample points and Second Order Reliability Method is performed to obtain reliability index and probability of failure. Five numerical examples are selected to illustrate the proposed algorithm. The limit state functions of three examples (cantilever beam, highly nonlinear limit state function and dynamic response of an oscillator) are defined explicitly and the others (frame and truss structures) are defined implicitly. ANSYS finite element program is utilized to obtain the response of the structures which are needed in the reliability analysis of implicit limit state functions. The results (reliability index, probability of failure and limit state function evaluations) obtained from the improved response surface are compared with those of Monte Carlo Simulation, First Order Reliability Method, Second Order Reliability Method and Classical Response Surface Method. According to the results, proposed algorithm gives better results for both reliability index and limit state function evaluations.

• Korean Journal of Remote Sensing
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• v.34 no.4
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• pp.625-638
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• 2018

In this paper, we derive i) a function to estimate snow cover fraction (SCF) from a MODIS satellite image that has a wide observational area and short re-visit period and ii) a function to determine snow depth from the estimated SCF map. The SCF equation is important for estimating the snow depth from optical images. The proposed SCF equation is defined using the Gaussian function. We found that the Gaussian function was a better model than the linear equation for explaining the relationship between the normalized difference snow index (NDSI) and the normalized difference vegetation index (NDVI), and SCF. An accuracy test was performed using 38 MODIS images, and the achieved root mean square error (RMSE) was improved by approximately 7.7 % compared to that of the linear equation. After the SCF maps were created using the SCF equation from the MODIS images, a relation function between in-situ snow depth and MODIS-derived SCF was defined. The RMSE of the MODIS-derived snow depth was approximately 3.55 cm when compared to the in-situ data. This is a somewhat large error range in the Republic of Korea, which generally has less than 10 cm of snowfall. Therefore, in this study, we corrected the calculated snow depth using the relationship between the measured and calculated values for each single image unit. The corrected snow depth was finally recorded and had an RMSE of approximately 2.98 cm, which was an improvement. In future, the accuracy of the algorithm can be improved by considering more varied variables at the same time.

• Fire Science and Engineering
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• v.30 no.1
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• pp.81-85
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• 2016

Reasonable disaster prevention signs play an important role in guiding evacuation. Through the field investigation on disaster prevention signs in shelters and surrounding areas in Beijing, some problems were found in the using of sign system. Based on the principle of integrated design, evacuation and rescue requirements, it is necesssary to make further study on aspects such as, design of function, systematic consideration, humanization design, as well as the internationalization using. This paper presents an evaluation index system for disaster prevention signs. Such a system is very important for strengthening the independent guiding function of sign systems and improving evacuation efficiency. An effective connection could be realized between the internal environment of buildings, evacuation routes, and emergencey shelters.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.2
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• pp.93-101
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• 2023

PURPOSE: The Western Ontario and McMaster Universities Arthritis (WOMAC) index has been used to measure the outcome of total knee replacement (TKR), but studies on its reliability and validity are limited. The present study examined the reliability and validity of this index for patients with knee osteoarthritis who underwent TKR. METHODS: Seventy-one inpatients and outpatients who underwent bilateral TKR for knee osteoarthritis were included in this study. The pain assessment scale and WOMAC index were used to evaluate the participants every two weeks to examine the test-retest reliability, internal consistency, and construct validity. RESULTS: The test-retest reliability scores for pain, stiffness, and physical function were .75-.92, .85-.90, and .75-.95, respectively. The corresponding intraclass correlation coefficients were .75-.88, .76-.88, and .71-.95, respectively. The internal consistency score in the first and second examinations was .92. Furthermore, the construct validity scores for pain, stiffness, and physical function were .83, .41, and .58, respectively. CONCLUSION: The application of the WOMAC index in patients who underwent TKR showed high test-retest reliability and internal consistency with the use of the WOMAC index and good validity with the use of the pain assessment scale.

• Smart Media Journal
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• v.10 no.3
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• pp.39-47
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• 2021

Enhanced index tracking is a problem of optimizing the objective function to generate returns above the index based on the index tracking that follows the market return. In order to avoid problems such as large transaction costs and illiquidity, we used a method of constructing a portfolio by selecting only some of the stocks included in the index. Commonly used enhanced index tracking methods tried to find the optimal portfolio with only one objective function in all tested periods, but it is almost impossible to find the ultimate strategy that always works well in the volatile financial market. In addition, it is important to improve generalization performance beyond optimizing the objective function for training data due to the nature of the financial market, where statistical characteristics change significantly over time, but existing methods have a limitation in that there is no direct discussion for this. In order to solve these problems, this paper proposes ensemble learning that composes a portfolio by combining several objective functions and a 3-stage portfolio selection algorithm that can select a portfolio by applying criteria other than the objective function to the training data. The proposed method in an experiment using the S&P500 index shows Sharpe ratio that is 27% higher than the index and the existing methods, showing that the 3-stage portfolio selection algorithm and ensemble learning are effective in selecting an enhanced index portfolio.

• The Journal of Korean Physical Therapy
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• v.18 no.6
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• pp.43-49
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• 2006

Purpose: Changes of degenerative disc have been analyzed or with the Magnetic Resonance Imaging (MRI) to assign appropriate meaning, and the relationship between the degenerative changes of the discs and its living function has been evaluated through the living function evaluation scores collected by functional rating index. Methods: in April, 2006, a physical examination was conducted for physical laborers to be employed as on-site laborer in a steel industrial complex located at a region. A month later, these 20 laborers who participated in lumbar vertebra MRI tests have been investigated for one-to-one mobile phone functional rating index test. Excluding 3 of 14 respondents whom scored 0 in functional rating index, the rest of respondents' degenerative disc grade changes shown in MRI and its relationship to living functional rating index have been performed. Results: The Dabbs method of measuring disc height resulted to show significant increase as the disc height changes from L1-2 level to L5-S1 level (p<0.01). However, there was no statistical significance with a relationship between disc height and functional rating index, and disc height average. The Magnetic Resonance Imaging analysis regard on the degree of disc degeneration and its relationship to living functional rating proved to have significant relationship (p<0.05). Conclusion: The degenerative changes monitored by Magnetic Resonance Imaging show significant relationship (p<0.05) to living function. However, this relationship could vary depend upon the characteristics of study population. So, it suggested that the future studies should be performed by considering population's age and job career.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2073-2081
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• 2002

In product design and manufacturing, axiomatic design provides a systematic approach for the decision-making process. Two axioms have been defined such as the Independence Axiom and the Information Axiom. The Information Axiom states that the best design among those that satisfy the independence axiom is the one with the least information content. In other words, the best design is the one that has the highest probability of success. On the other hand, the Taguchi robust design is used in the two-step process; one is "reduce variability," and the other is "adjust the mean on the target." The two-step can be interpreted as a problem that has two FRs (functional requirements). Therefore, the Taguchi method should be used based on the satisfaction of the Independence Axiom. Common aspects exist between the Taguchi method and Axiomatic Design in that a robust design is induced. However, different characteristics are found as well. The Taguchi method does not have the design range, and the probability of success may not be enough to express robustness. Our purpose is to find the one that has the highest probability of success and the smallest variation. A new index is proposed to satisfy these conditions. The index is defined by multiplication of the robustness weight function and the probability density function. The robustness weight function has the maximum at the target value and zero at the boundary of the design range. The validity of the index is proved through various examples.gh various examples.

• Quality Improvement in Health Care
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• v.5 no.1
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• pp.128-138
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• 1998

Background : There is increased recognition that rigorous approach to functional assessment will complement the assessment of clinical status. This study is to develop the appropriate visual function index in Korean patients with cataracts by the assessment of the reliability, validity of visual function indexes including VF-14. Methods : An prospective study was performed with 92 patients who had undergone either one eye or both eye cataract surgery by 3 ophthalmologists practicing at a university hospital. Patients were interviewed. and clinical data were obtained. Doctors were questioned with self-entered questionnaire forms. Medical record was examined to understand surgery process. The survey was conducted at 1-2 days before cataract surgery. Results : We used following measures : 7 visual function indexes, global measures of patients' trouble and satisfaction with vision, and best-corrected visual acuity(VA) in each eye. 7 visual function indexes showed a high internal consistency reliability (Cronbach's alpha coefficients ${\geq}$ 0.86). The better visual acuity(operated eye, better eye), the higher patient satisfaction with vision, the lower symptom score, the lower patient trouble with vision was correlated with preoperative visual function index scores. Among 7 indexes, VF-12 with the exclusion of 2 items drivings from VF-14 is a high Cronbach's alpha coefficient and correlation coefficient and the highest $R^2$. Conclusion : We conclude that VF-12 is reliable and valid in Korea. So we suggest that in Korea, all items of VF-14, the visual function index, which is in use internationally, ought to be surveyed and VF-12 which has been excluded by 2 items of drivings from VF-14 ought to be used for analysis.

• Women's Health Nursing
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• v.22 no.4
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• pp.287-296
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• 2016

Purpose: This study identified the level of marital intimacy, menopausal symptom and sexual function, and examined factors affecting sexual function in postmenopausal married women. Methods: With cross-sectional survey, a sample of 245 subjects aged 45 to 60 years was recruited from January to March, 2014. Data were collected using self-reported questionnaires which included marital intimacy questionnaire (MIQ), menopause rating scale (MRS), and female sexual function index (FSFI). Data were analyzed by descriptive statistics, t-test, ANOVA, Pearson correlation coefficients and stepwise multiple regression. Results: Marital intimacy, menopausal symptom and sexual function scores of subjects were $3.46{\pm}1.14$, $13.71{\pm}6.61$, and $12.55{\pm}8.33$, respectively. Marital intimacy and menopausal symptom were related to sexual function. Variables including marital intimacy, psychosocial and urogenital menopausal symptom, period since menopause and body mass index therapy explained 51.5% in sexual function of participants. Conclusion: When nurses plan sexual counseling and education for sexual function of postmenopausal married women, it is necessary to consider marital intimacy, menopausal symptoms, and menopause-related factors.