• Journal of Information Processing Systems
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• v.6 no.1
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• pp.43-52
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• 2010

In the secure communication areas, three-party authenticated key exchange protocol is an important cryptographic technique. In this protocol, two clients will share a human-memorable password with a trusted server, in which two users can generate a secure session key. On the other hand the protocol should resist all types of password guessing attacks. Recently, STPKE' protocol has been proposed by Kim and Choi. An undetectable online password guessing attack on STPKE' protocol is presented in the current study. An alternative protocol to overcome undetectable online password guessing attacks is proposed. The results show that the proposed protocol can resist undetectable online password guessing attacks. Additionally, it achieves the same security level with reduced random numbers and without XOR operations. The computational efficiency is improved by $\approx$ 30% for problems of size $\approx$ 2048 bits. The proposed protocol is achieving better performance efficiency and withstands password guessing attacks. The results show that the proposed protocol is secure, efficient and practical.

• IE interfaces
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• v.25 no.4
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• pp.431-440
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• 2012

Since pooling is a popular scheme in many areas to attain operational excellence, many researchers investigated the performance of pooling systems. However, rare research could be found on pooling with game situation which has much applicability to real world phenomenon. We analyze the performance of noncooperative pooling system with two servers having different sharing capacity. We investigate the sensitivity of the advantage of capacity pooling on the variation of system parameters, including sharing capacity numbers, pooling probability, pooling strategy and traffic intensity. As a result, we suggest an efficient control policy which facilitate the performance of pooling in a game situation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.230-239
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• 2018

Objective: The purpose of this study is to identify the kinds and exposure levels of health hazards in the metalworking process in relation to acute poisoning accidents caused by methanol in 2016. Methods: The number of industries, workplaces, exposed workers, regional distribution, and exposure level of health hazards in metalworking process were investigated based on employee exposure assessment database provided by KOSHA (the Korea Occupational Safety and Health Agency), which was collected from workplace hazard evaluation programs in Korea. Exposure metrics for methanol were assessed by RCR (risk characterization ratio). Results: The numbers of processes, workplaces, and exposed workers of metalworking, which include CNC (computer numerical control) were 25, 14,405, and 169,102 respectively. The numbers of samples of chemical hazards including methanol were 91,325, and it was found that workers in metalworking were exposed to 249 kinds of chemical hazards. There were 16 kinds of special controlled substances including beryllium. It is estimated that the number of workplaces involving CNC process was 2,537, and the number of exposed workers was 27,976. In CNC process, the total number of workplaces handling methanol was 36, and 298 workers were estimated to be exposed. There was no exceeded that surpassed the OEL and 49% of samples were below the limit of detection. Methanol exposure concentrations in Gyeonggido Province were statistically significantly higher than in other areas (p <0.0001). Conclusions: In the metalworking process including CNC, there is exposure to a wide variety of health hazards. There was no sample exceeding the OEL for methanol. Therefore, it is necessary to recognize the limits of the employee exposure assessment system and urgently improve measures to prevent the occurrence of events like methanol poisoning.

• Research in Mathematical Education
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• v.5 no.2
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• pp.107-118
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• 2001

Mathematics subject of the seventh national curriculum in Korea, which has been effective since 2000, strongly encourages the use of calculators and computers to help children gain a better understanding of basic mathematical concepts and develop creative thinking and problem-solving skills without spending too much time and effort on making mechanical computations. Despite the recommendation by the national curriculum, however, only a small segment of elementary school teachers have been using calculators because of the fear that children\\`s dependence on calculators might bring about negative consequences. As a result, little research has been conducted in this area as well. This study has been conducted on the assumption that calculators have the potential for being a useful instructional tool in certain areas of elementary school mathematics education. To investigate the usefulness of calculators, a review was made of the scanty literature in the area. The literature review indicated that calculators are effective when they are used for the following purposes: understanding concepts and properties in numbers and operations, deducing mathematical rules, and solving problems. In view of the available research finding, we will give some concrete learning and teaching models of such uses of calculators. The teaching-learning models are organized around three categories: concept formation, discovery of principles and rules, and problem solving. Such organization is intended to help teachers use the models with ease.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.143-150
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• 2016

This paper's aim is to suggest the Expert System for analyzing relative combat power in ground operations. Since relative combat power analysis in terms of comparing combat power of friendly forces with one of the enemy can determine how the commander and staffs operate their unit afterwards, it requires fast and rational decision-making process. However, it has relied on manual method so far though Tactical Information Communications Network(TICN) into which numbers of applications can be loaded has been developed over a decade. 3 methods for analyzing relative combat power were expressed as mathematic rules to be used knowledge in the expert system after reviewing previous studies, and it studied how intangible power as well as tangible were reflected on total combat power. The expert system that will be built using EXSYS Corvid tool is expected to lessen error rate, provide faster decision-making, and reflect both intangible combat power and tangible one by using an appropriate weights in analyzing relative combat power. Next research filed includes how to build expert systems related with military personnel and intelligence areas for fast and rational decision-making processes.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.4
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• pp.621-641
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• 2017

The purposes of this study were to identify the characteristics of students with different cognitive styles in the communication process according to the types of mathematical tasks and investigate the effects of their cognitive styles and types of mathematical tasks on their mathematical communication. For this, the investigator selected subjects according to the field dependent-field independent cognitive style by Witkin et al.(1977, p. 7). Mathematical tasks were developed in the areas of numbers and operations, regularity, and measurement according to the four types of Stein & Smith(1998, p. 269), which include the Memorization, Procedures without Connections, Procedures with Connections, and Doing Mathematics tasks. The selected students were divided into homogeneous groups according to their cognitive styles, and their communication processes according to the four types of mathematical tasks were observed through participation and videotaped. The videotapes were then transcribed and analyzed in protocols. The conclusions is that mathematical tasks of high cognitive level had positive effects on the activation of significant mathematical communication among the students and that differences in approaches to tasks according to their cognitive styles influenced their communicative activities in speaking and listening.

• Journal of Educational Research in Mathematics
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• v.18 no.2
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• pp.179-200
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• 2008

In this paper, we analyzed the characteristics of the gender difference with the results of National Assessment of Educational Achievement(NAEA) from 2004 to 2006, which subjects are 3rd, 9th and 10th graders. First, we analyzed the characteristics of the achievement by the scale scores, according to years, achievement standards, grades. Second, we surveyed the number of items and ratio which male/female prevails and its characteristics according to grades, difference levels, content areas(i.e., numbers and operations, figures, measurement, probability and statistics, letters and formulas, patterns and function). Furthermore, we perform in-depth analysis of the items which gender difference in correct response proportion is more than 7% and analyze the cause of gender difference of achievement. This paper provides large valid data about gender difference by the results of NAEA. It can give suggestions with regard to policy making.

• Journal of the Korean School Mathematics Society
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• v.13 no.3
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• pp.415-442
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• 2010

If the philosophy of the curriculum is changed when the curriculum is revised, discussion about knowledge viewpoints in the changed philosophy is needed. The purpose of this thesis is to analyze elementary mathematics textbooks(EMT) based on the perspective of constructivism knowledge as basic philosophy of the 7th curriculum and the 2007 revised curriculum and to present aim of textbooks development through the results. According to the results, the number and operation units of 1st and 2nd grades of EMT compiled according to the 7th curriculum and the 2007 revised curriculum didn't reflect the perspective of constructivism knowledge as the philosophy of the curriculum. From the analysis, EMT were not composed so as to agree the perspective of constructivism knowledge that emphasize concepts, conceptua1 principles, variety, integration.

• Advances in pediatric surgery
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• v.7 no.1
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• pp.46-53
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• 2001

To understand the current status of neonatal surgery in Korea, a survey was made among the 36 members of the Korean Association of Pediatric Surgeons. The response rate was 75 % (26 surgeons in 20 hospitals). Five hundred fifty three neonatal surgical patients treated in 1999 were analyzed. Regional numbers of patients were closely related to the regional population in most areas. Ano-rectal malformations (17 %), pyloric stenosis (16 %), Hirschsprung's disease (13 %), atresia/stenosis of the gut (11 %), esophageal atresia (8 %) were the most common anomalies treated. The majority of operations were done within the first week of life. Seventy one per cent of cases were major life threatening or so-called neonatal index cases. Over-all mortality was 8 per cent. Higher mortality was observed in patients with diaphragmatic hernia (26 %), gastro-intestinal perforation (18 %), NEC (18 %), and esophageal atresia(14 %). Higher mortality was observed in patients with extremely low birth weight (33%) and low birth weight (18 %). Associated anomalies were observed in 20 %. Prenatal ultrasound was performed in 36 per cent with sensitivity of 20 %. Result of this study was compared to the previous report (1994) and that of Japan (1998).

• The Mathematical Education
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• v.59 no.2
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• pp.167-183
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• 2020

This study is an analysis study on the number and operation area of middle school mathematics curriculum. This study is a literature analysis study that analyzes the historical transition process of number and operation area, and suggests the restructuring direction of mathematics learning contents for numbers and operation areas based on the results. In order to achieve this research purpose, the contents of the number and operation areas suggested from the 1st middle school mathematics curriculum to the 2015 revised middle school mathematics curriculum were considered. In addition, in this study, analysis of the mathematical learning contents of number and operation area was conducted. The details of the study are as follows. First, it was decided as a tertiary mathematics curriculum as a criterion for analysis. Second, a basic analysis framework was developed by subdividing the content of mathematics learning into content elements and terminology elements. Third, on the basis of the developed analysis framework, mathematics learning contents that are the core issues of number and operation area were extracted. Fourth, the extracted mathematics learning contents were compared with foreign curriculum. Finally, based on the analysis results, the direction of restructuring for the number and operation area of middle school was suggested. The results of this study are expected to be the basis for the development of a new curriculum.