• Journal of the Korean Institute of Navigation
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• v.14 no.2
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• pp.15-31
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• 1990

Recently, there is a tendency to design the large full ships with lower-powered engine as the means for energy saving in ship's navigation at seas. Such a lower-powered ship is anticipated to show the different propulsive performance in rough seas, because the fluctuation of main engine load of lower powered ship is relatively large as compared with higher-powered ship is relatively large as compared with higher-powered ship. The fluctuation of propeller load is nonlinear at racing condition in waves. It is due to the variation of inflow velocity into propeller, the propeller immersion and the characteristics of engine governor. In this paper, the theoretical calculation of the nominal speed loss and the numerical simulation for the nonlinear load fluctuation of a model ship in rough seas are carried out. From the results of calculation, the following are discussed. (1) The ratio of nominal speed loss to the speed in still water. (2) The manoeuvring ability of ship and the operational ability of main engine in a seaway. (3) A method of the evaluation for the fluctuation of propeller torque and revolution on the engine characteristics plane. (4) The effect of engine governor characteristics on the propeller load fluctuation.

• Journal of Power Electronics
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• v.19 no.1
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• pp.119-133
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• 2019

Although the dual modulation wave method can solve the low-frequency neutral point potential (NPP) fluctuation problem for three-level neutral point clamped converters, it also increases the switching frequency and limits the zero-sequence voltage. That makes it harmful when dealing with the NPP drift problem if the converter suffers from a long dead time or asymmetric loads. By introducing two degrees of freedom (2-DOF), an NPP control based on a search optimization method can demonstrate its ability to cope with the above mentioned two types of NPP problems. However, the amount of calculations for obtaining an optimal 2-DOF is so large that the method cannot be applied to certain industrial applications with an inexpensive digital signal processor. In this paper, a novel optimal 2-DOF-based NPP control is proposed. The relationships between the NPP and the 2-DOF are analyzed and a method for directly determining the optimal 2-DOF is also discussed. Using a direct calculation method, the amount of calculations is significantly reduced. In addition, the proposed method is able to maintain the strongest control ability for the two types of NPP problems. Finally, some experimental results are given to confirm the validity and feasibility of the proposed method.

• Journal of the Korean Home Economics Association
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• v.35 no.4
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• pp.111-124
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• 1997

The purpose of this study was to find out the effects of children's elementary school entrance age and sex on cognitive and social abilities. The subjects were 80 the same number was slected by elementary school entrance age(5-year and 6-year) and sex. Their cognitive and social abilities were measured by Intelligence Maturity Test and Revised Vineland Adaptive Behavior Scales. The data were statistically analyzed including descriptive statistics and multivariate analysis of variance. The results were as follows: 1) 6-year-old children had higher perceptive ability of sameness and calculation ability than 5-year-old children. Girls also had higher IQ and language concept than boys, 2) 6-year-old children's communication socialization and total social ability were higher than those of 5-year old children Girls' communication and total social ability were higher than those of boys. The implication was that it would be important to consider children's social ability if their entrance age were decided. In addition Early Entrance to Elementary School system should be reconsidered in the point of childer's developmental adaptation.

• Korean Journal of Culture and Social Issue
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• v.11 no.4
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• pp.83-95
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• 2005

The purpose of the present study was to investigate the relationship between spatial-erceptual ability and several aspects of driving-related situation awareness(in particular, recognition and prediction). Video clips of real driving were used in both recognition and prediction tasks, and the digit calculation task during driving the simulator was required as the integration task of recognition and prediction. The results showed that the subjects of higher spatial-perceptual ability performed better in recognition task, especially in terms of sensitivity measured in d'(as signal detection theory), prediction task, and digits calculation performance than those of lower spatial-perceptual ability.

• Journal of The Korean Association For Science Education
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• v.24 no.5
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• pp.814-824
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• 2004

This article presents the effects of estimation activities related to speed and density on students' concept-understanding, answer-prediction, and answer-calculation in problem solving procedure with quantitative and qualitative methods. Participants were one hundred and ninety two seventh graders from one coeducational school in Seoul. Half of them participated in the estimation activities and the other half did in the measurement activities. Discussions of three students during estimation activities on density and their post-interviews were tape-recorded. Pre- and post-assessment scores were analyzed for the whole classes, and students' discussions and interviews served this research as evidences for the case analysis. Results of scores indicated that students in the estimation activities were significantly better than those in the measurement activities for predicting answers, but not for understanding concepts. Analysis of the cases revealed that estimation activity helped them to understand the relations of mass, volume and density, empirically, which enhanced their prediction ability. Furthermore, the ability could help a student with low calculation ability to comprehend the calculation problems. Thus, it is concluded that estimation activities could influence students' empirical learning on quantitative concepts, which enhanced their prediction ability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2251-2261
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• 2013

The objective of this study was to develop and evaluate learning smartphone application for improving drug dosage calculation ability of nursing students. We evaluated the contents based on the sufficient teaching materials and developed the process for implementation of the educational system. The participants were 37 nursing students. After implementation during 4 weeks, data was analyzed with the SPSS WIN 18.0. There were significant differences of achievement of learning objectives(${\chi}^2$=10.90, p=.004), application to work(Z=2.86, p=.004), mathematical confidence (Z=3.07, p=.002), according to the frequency of program use, but there was no difference in academic self-efficacy. Based on the results of this study, developed smartphone application will help to strengthen the drug dosage calculation ability of nursing students. And also, the results suggest that more powerful application for improving academic efficacy and increasing participation should be developed.

• Knowledge Management Research
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• v.18 no.1
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• pp.159-176
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• 2017

Recently, the popularity of smartphones has led to a dramatic increase in the frequency of use of App(Application) services. LBS (Location-Based Service) App service adopts various methods such as push marketing and useful information by region through providing location-based service based on the location of the consumer. In particular, an enterprise or an App management company can provide necessary information to the consumer through the necessary information among the customer related knowledge information obtained by utilizing the location information of the consumer in real time. Nevertheless, since LBS is a service that can be performed only when the company obtains consent to provide location information voluntarily by the consumer, there is a case of privacy infringement due to consumers' use of personal information. The purpose of this study is to identify the characteristics of privacy related variables and the knowledge structure for consumer value formation based on the theory of privacy calculation. We also compared the characteristics of Korea with those of China in privacy issue. As a result of the analysis, it was confirmed that factors such as information utilization ability and information control ability were influential as a key factor of privacy calculation. In addition, perceived value influences the reputation of the LBS App service.

• Journal of Korean Society for Quality Management
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• v.50 no.2
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• pp.199-220
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• 2022

Purpose: The purpose of this study is to analyze the score data released by the Korea Institute of Curriculum and Evaluation to find out the problems with the current scoring system provided by the College Scholastic Ability Test and to suggest improvement measures to solve these problems. Methods: We calculated the descriptive statistics of the standard scores using the frequency distribution table of the standard scores and identified the characteristics of the standard scores by expressing the distribution as a graph. Also, we developed an index to evaluate whether each stanine level was stably assigned and calculated the indexes for each area/subject by using the data on the number of examinees for each level. Results: We found that the relationship of conversion from raw scores to integerized standard scores is different depending on the size of the standard deviation of the raw scores, and identified the problem that the raw score information is not fairly reflected in the calculation of the percentile and level as the two raw scores are converted to one standard score. This problem can be solved by calculating the standard score to a decimal point. Conclusion: In this study, as a way to improve the quality of the scores of the current CSAT, the standard score and percentile decimal notation, the specific regulations of the standard score and stanine level calculation method, and the expansion of the open range of the scores were suggested.

• Journal of Korean Biological Nursing Science
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• v.16 no.2
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• pp.113-122
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• 2014

Purpose: This study was to identify predictors of drug dosage calculation error risk in newly graduated nurses. Methods: A total of 115 newly graduated nurses who passed their employment examination, but didn't work for hospital yet, were recruited from a university hospital. The data were analyzed by descriptive statistics, $X^2$-test, t-test, ANOVA, Pearson correlation coefficients, and stepwise multiple regression using the SPSS 18.0 program. Results: The mean score of 'drug dosage calculation ability' was $0.81{\pm}0.16$ and the mean score of 'certainty of calculation' was $2.95{\pm}0.60$ out of a 5 point scale. The error risk of drug dosage calculation was positively related to anxiety for drug dosage calculations (r=.388, p<.001), but negatively related to interest and confidence in mathematics (r=-.468, p<.001), confidence related to dosage calculations (r=-.426, p<.001). The main predictors of error risk related drug calculations in newly graduated nurses were identified as interest and confidence in mathematics (${\beta}$=-.468, p<.001). This factor explained about 21.9% of the variance in error risk of drug dosage calculation. Conclusion: The strategies used to decrease the error risk related drug dosage calculation such as improving interest and confidence in mathematics should be developed and implemented.

• The Mathematical Education
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• v.24 no.2
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• pp.74-104
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• 1986

This study aims at investigating the correlation between such variables as a child's family circumstance and personality and that of the child's mathematical ability. For the objects of the study five hundreds and sixteen students (male 273, female 243) were andomly selected from the fifth grade primary school students in the city of Seoul. For the tool of measure the investigation of Korean family circumstances with particular characteristics, the personality test by Chong Pom Mo and Kim Ho Kwon, and the intelligence test by Lee Sang Ro, Chin Whal Kyo and Pyon Chang Jin were employed. For the statistical analysis S. A. S. C., the statistical analysis package of KAIST was employed. The resutis of the test can be summarized as follows. The correlation between the variable of family Circumstance and that of mathematical alility 1) In case of the significance level 0.05 the education of the childs mother and the order of the child's birth have much to do with the perception speed. In case of the significance level 0.1 it makes some difference in the child's perception spead whether the clild's mother has a job or not. 2) In case of the significance level 0.05 the education of the child's father and mother, the father's job and the type of habitation have influence on the child's perception of space. 3) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the order of the child's birth, the type of habitation, their religion, and their cultural, and economic standard have influence on the child's ability of inference. 4) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the type of habitation, their religion and their cultural and economic standard have influence on the child's ability of calculation. 5) In case of the significance level 0.05 any variable of the child's family circumstance has nothing to do with the child's memory. In case of the significance level 0, 1 the type of family and the type of habitation have effect on the child's memory. 6) In case of the significance level 0.05 the education of the child's parents, the jobs of the parents, the type of habtation, their religion, and their cultural and economic standard have influence on the child's linguistic notion. The correlation between the variable of the child's personality and that of the child's mathematical ability 1) In regard to the priority of the variables influencing the child's perception speed, the child's discretion comes first in order, and then sociability and impulsiveness of the child. 2) The child's discretion has effect on the child's space perception. 3) The child's discretion has effect on the child's ability of inference. 4) In regard to the child's ability of calculation the child's discretion comes first in order, and then impulsiveness and sociability of the child. 5) The child's discretion has effect on memory. 6) The child's discretion has effect on the child's linguistic notion.