• Journal of applied mathematics & informatics
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• v.32 no.1_2
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• pp.61-74
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• 2014

This paper describes an iterative method for orthogonal projections $AA^+$ and $A^+A$ of an arbitrary matrix A, where $A^+$ represents the Moore-Penrose inverse. Convergence analysis along with the first and second order error estimates of the method are investigated. Three numerical examples are worked out to show the efficacy of our work. The first example is on a full rank matrix, whereas the other two are on full rank and rank deficient randomly generated matrices. The results obtained by the method are compared with those obtained by another iterative method. The performance measures in terms of mean CPU time (MCT) and the error bounds for computing orthogonal projections are listed in tables. If $Z_k$, k = 0,1,2,... represents the k-th iterate obtained by our method then the sequence of the traces {trace($Z_k$)} is a monotonically increasing sequence converging to the rank of (A). Also, the sequence of traces {trace($I-Z_k$)} is a monotonically decreasing sequence converging to the nullity of $A^*$.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.1
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• pp.27-35
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• 2000

For a weighting method to be practically valid, it should produce weights which coincide with the relative importance of attributes perceived by the decision maker. In this paper, 'bootstrapping' is used to compare the practical validities of five weighting methods frequently used; the rank order centroid method, the rank reciprocal method, the rank sum method, the entropic method, and the geometric mean method. Bootstrapping refers to the procedure where the analysts allow the decision maker to make careful judgements on a series of similar cases, then infer statistically what weights he was implicitly using to arrive at the particular ranking. The weights produced by bootstrapping can therefore be regarded as well reflecting the decision maker's perceived relative importances. Bootstrapping and the five weighting methods were applied to a job selection problem. The results showed that both the rank order centroid method and the rank reciprocal method had higher level of practical validity than the other three methods, though a large difference could not be found either in the resulting weights or in the corresponding solutions.

• Journal of Environmental Impact Assessment
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• v.6 no.1
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• pp.111-119
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• 1997

This study was carried out to suggest the best statistical test which may be used to quantify the change of water quality between two groups. Traditional t-test may not be used in cases where the normality of underlying population distribution is not assured. Three non-parametric tests which are based on the relative order of the measurements, were studied to find out the applicability in water quality data analysis. The sign test is based on the sign of the deviation of the measurement from the median value, and the binomial distribution table is used. The signed rank test utilizes not only the sign but also the magnitude of the deviation. The Wilcoxon rank-sum test which is basically same as Mann-Whitney test, tests the mean difference between two independent samples which may have missing data. Among the three non-parametric tests studied, the singed rank test was found out to be applicable in the quantification of the change of water quality between two samples.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.790-805
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• 1988

Static strength and fatigue life scattering of glass fiber reinforced epoxy composite materials has been studied. Normal, lognormal, two-parameter and three-parameter Weibull distribution functions are used for strength and one-stress fatigue life distribution. The value of mean fatigue life is analysed using mean fatigue life, mean log fatigue life and expected value of 2 and 3-parameter Weibull distribution functions. Modification on non-statistical cumulative damage models is made in order to interpret the result of two-stress level fatigue life scattering. The comparison results show that 3-parameter Weibull distribution has better predictions in static strength and one-stress level fatigue life distributions. However, no advantage of 3-parameter Weibll distribution is found over 2-parameter Weibull distribution in two-stress level fatigue life predictions. It is found that two-stress level fatigue life prediction by the expanded equal rank assumption is close to the experimental data.

• Journal of Korea Multimedia Society
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• v.12 no.9
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• pp.1210-1216
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• 2009

In this paper we analyze the convergence behavior of the recursive least rank (RLR) L-filter. The RLR L-filter is an order statistics filter, filter coefficients of which are the weights according to the order of magnitude of inputs. And RLR L-filter is a non-linear adaptive filter, that uses RLR algorithm for coefficient updating. The RLR algorithm is a non-linear adaptive algorithm based on rank estimates in Robust statistics. The mean and mean-squared convergence behavior of the RLR L-filter is examined with variable step-sizes. The RLR L-filter adapts the median filter type to the heavy-tailed distribution function of impulse noise, and adapts the average filter type to Gaussian noises.

• Journal of Korean Academy of Nursing
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• v.13 no.3
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• pp.106-118
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• 1983

The main purpose of this study is to systematically classify words indicating pain in terms of their ranks in each subclass. This study is a part of developing a Korean Pain Measurement Tool. This study didnot include exploration of each word's dimension such as sensory or affective. Eighty three Korean words tentatively classified in 19 subclasses in previous study were used for this study. At least three to six words were included in each subclass and the words were randomly placed in which each subject indicates their rank of pain degree. One hundred and fifty nursing students and one hundred clinical nurses were requested to indicate the rank of each word. One hundred and sixteen students and eighty three nurses completed the ratings for analysis. The data were collected from June 1983 to July 1983. The data using ordinal scale were analyzed by Friedman ANOVA to test significant difference between rank means. All of pain words indicated significant rank mean difference in all of 19 subclasses. Some of the words were either cancelled or replaced by other words, or rearranged for their ranks. Subclasses of which words were cancelled were 1) Simple stimulating pain, 2) Punctuate pressure, 3) peripheral nerve pain, 4) radiation pain, 5) punishment-related pain, and 6) suffering-related pain. Subclasses of which words were replaced or rearranged were 1) incisive pressure, 2) constrictive pressure, 3) dull pain, 4) tract pain, 5) digestion-related pain and 6) fear-related pain. Four subclasses such as traction pressure, thermal, cavity pressure, and fatigue- elated pain indicated significant differences among rank means in each subclasses and showed no visible overlaps of the ranks among means. Further research is needed using high level measurement of pain degree of each word and more sophisticated analysis of the pain degrees. Three pain words which would be related to chemical stimulation were newly explored and included as a new subclass. Through this study, the total number of subclasses increases from 19 to 20 and the total number of Korean words in the scale decreases from 83 to 80.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.177-193
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• 2022

In the near future, it is expected that the use of autonomous mobility-on-demand services will increase. Considering its complicated service components, including vehicle convenience, driving and matching speed, and platform convenience, the priorities of them will need to be determined for a successful establishment. In this context, this study examined the importance rank of each service component through an online survey of potential users of autonomous mobility-on-demand services. As a result of the AHP (Analytic Hierarchy Process) with respect to the upper-level components, driving and matching speed component is selected as most important, followed by platform convenience and vehicle convenience. Mean rank analysis with respect to lower-level components showed that the in-vehicle congestion level of vehicle convenience, waiting time of driving and matching speed, and pre-booking availability of platform convenience each ranked first. Additional analysis regarding each group was conducted to establish a group-specific strategy. As a result, it would be better to focus on a vehicle than a mobile platform when designing services for the region with a high proportion of the older. Moreover, it is recommended to speed up the driving and matching speeds more than the current public transport, alleviate in-vehicle congestion, and enable the users to book the schedule in advance.

• Journal of Family Resource Management and Policy Review
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• v.2 no.1
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• pp.103-117
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• 1998

The purpose of this study were (1)to investigate the housewives’value orientation toward environmental effect, (2)to examine the effect of environments and value-orientation on housewives’green-consumption behavior and (3)to analyze the hypothesized causal direct or indirect explanation effect among the housewives’green-consumption behavior. The 310 subjects of this study were selected from housewives lived in Seoul. The data obtained were analyzed by Mean, Pearson’s correlation, and Stepwise Multiple Regression Analysis. The major results were as follows: 1) The mean score of housewives’value-orientation was 4.45 out of 5. The value-orientation of housewives was affected by the following variables in order to: environmental pollution and participation I community organization. 2) The mean score of housewives’green-consumption behavior was 3.62 out of 5. The housewives’green-consumption behavior was affected by the following variables in order : value orientation, environmental knowledge, participation in community organization, mass media and recycling system. 3) The most influential variables on the housewives’ green-consumption behavior were in the rank of the value orientation(R²=.39). mass meia(R²=.11). and environmental knowledge(R²=.07).

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.495-502
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• 2007

Species biotic index (SBI), based on a fish assemblage, was applied to a stream assessment using long-term ecological fish data set (1996 to 2001) in Boryong dam area, which is located in the mainstream of Ungchun Stream of Chungnam province, Korea. According to the methods of Hilsenhoff (1988), the scores of tolerance guild assigned 10 classes to each species by its habitat and feeding guild, but modified current 7 criteria to 5 scoring standards due to unclear borderline among species. Relative abundance in the species number of upper stream guilds was only 7% of the total, whereas the abundance in the species number of middle to downstream upper stream guilds was 64%. Mean SBI, based on dataset in Site 1 during 1995-2001 averaged 5.10, which was judged as a "good" condition by the rank criteria of SBI. Before the dam construction, mean SBI in the Site 1 was 4.61, indicating a "good" condition, but after the dam construction, mean SBI was 5.60, indicating a "fair" condition. Trajectory analysis in the Site 1 showed significantly (One-way ANOVA, $F_{6,21}=3.26$, p=0.02) different among years, reflecting the changes of fish composition and population density by the dam construction, whereas Site 2 showed no significant changes ($F_{6,21}=1.00$, P =0.45) difference among years. Mean SBI prior to the dam construction in the Site 3 was 4.52 but after the construction, the value was 6.30, indicating a distinct difference between the pre- and post-dam construction. Trajectory analysis at the Site 3 supported this fact: Values of SBI showed significantly ($F_{6,21}$=14.37, p<0.01) different. Mean SBI was 4.67 in the Site 4, indicating a "good" condition in the health and the health rank was same as the sampling sites 1, 2, and 4. Trajectory in the Site 4 showed no significant ($F_{6,21}=2.35$, p=0.07) difference among the years. Overall, our trajectory analysis indicated that three of four sampling sites (sites 1, 3, 4) showed significant decreases (n=7, p<0.05) and that the proportions of sensitive species declined evidently in the sites 1 and 2 and the tolerant species increased in the dam sites. Our outcomes may be used as a key data for diagnosis of the long-term ecological impact in the future in the watershed.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.8 no.1
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• pp.31-36
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• 2010

Purpose : The purpose of this study was to investigate the effects of core exercise on the static balance for females in their twenties. Methods : The core exercise program was conducted 3 times per week for 4 weeks. The result is based on the analysis of measuring static balance before and after the core exercise program. By using the GOOD BALANCE system, the assessment of the static balance ability was made before and after the exercise of 6 postures: normal standing, one left leg?and one right leg standing with eyes open and closed respectively. For each case, the experimental data were obtained in 3 items: mean X speed, mean Y speed, and velocity moment. Statistical analysis was performed using SPSS/Win(10.0) version and Willcoxon signed rank test. Results : From the result of this study, we found that mean X speed, mean Y speed and velocity moment of total postures significantly increased after the 4 week program of core exercises. Conclusion : These finding indicate that core exercises could be beneficial to females in their twenties due to the effect of increasing static balance.