• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.10
• /
• pp.499-506
• /
• 2005

The growth of networks increase the importance of electronic commerces. Since the fair exchange protocol is an important part of electronic commerces, a number of researches have been done in relation to the fair exchange protocol. As the contract signing protocol is a part of fair exchange protocol, many protocols have been proposed, but most of them were focused on two-party protocol. Only a few were on the multi-party contract signing protocol. So far the optimistic multi-party contract signing protocol presented by Baum-Waidner has the least number of rounds in asynchronous network[4]. But, the lower bound on the number of rounds required by any optimistic multi-party contract signing protocol has been not known. In this paper, we present a tight lower bound on the number of rounds for optimistic multi-party contract signing protocol.

• Journal of the Korean Chemical Society
• /
• v.51 no.6
• /
• pp.560-568
• /
• 2007

The aim of this study is to investigate the terminology of chemically unclear ‘heavy metals' which were expressed in the Korean secondary science textbook in terms of the definition, the type and the meaning. Initial results showed that six of ‘Chemistry I' textbooks among these texts defined a heavy metal with the density and described it as a metal which is hazardous and continuously accumulated in the human body. Specifically, cadmium, lead and mercury were presented as examples of the hazardous metal in all of the eight textbooks but non-metals such as arsenic and absolutely essential metals including chrome, manganese, iron, cobalt, nickel and copper were also given in the texts. Most of the texts described the hazardousness and toxicity of the metal too simple to understand the mechanism of its intoxication despite considering all of the factors including its oxidation state, residual amount and reactivity with biomolecules of the human body. Such an ambiguous definition and explanation may excluded in the textbook because the chemically undefined chemical vocabulary leads students to cause an alternative conception of the heavy metal, which means that the metal could be identical with toxins.

• Communications of Mathematical Education
• /
• v.34 no.3
• /
• pp.373-391
• /
• 2020

This study is an analytical study on textbooks of , which was first presented in the 2015 revised high school mathematics curriculum. The textbook has a very high educational significance in that it is the first textbook developed for students majoring in economics. Analyzing whether these textbooks faithfully follow the spirit of the curriculum is an essential study for nurturing creative and convergent human beings and for personal self-realization. Therefore, in this study, a consistency analysis was conducted to determine whether the textbook fits the textbook development direction suggested by the curriculum developer and is appropriate for the state-approved mathematics curriculum. As a result of analysis, the contents of the textbook did not partially meet these criteria and lacked consistency. In conclusion, it is necessary to prepare more thorough standards for the examination and recognition of high school elective courses in the future.

• Journal of The Korean Association For Science Education
• /
• v.31 no.6
• /
• pp.1009-1024
• /
• 2011

Previous studies showed that many secondary school students and teachers have difficulties in distinguishing the phenomena of dissolution and diffusion, as well as the phenomena of diffusion and effusion. In this study, currently accepted term definitions of dissolution, diffusion and effusion were searched from the IUPAC Gold Book and the physical chemistry textbooks, and the points to differentiate the definitions were sought. Also, the term definitions of these three phenomena in the secondary school text books and the college general chemistry textbooks were surveyed and compared to the currently accepted definitions. It was found that dissolution is formation of one new phase from mixing two phases, while diffusion is the migration of matter down from the concentration gradient. The "concentration gradient" is considered to be a key point to distinguish diffusion from the dissolution. However, the concentration gradient was not mentioned in the definitions of diffusion in most of the secondary school textbooks and the college general chemistry textbooks. Effusion is differentiated from diffusion by the gas molecules escaping from the container through a tiny hole without collision. The definition of effusion was not found in most of the secondary school textbooks.

• Journal of the Korean School Mathematics Society
• /
• v.22 no.4
• /
• pp.351-367
• /
• 2019

Slope is an important mathematical concept that is connected to advanced mathematics as well as a basic concept as an indicator of the steepness of a straight line. The purpose of this study is to see how the concept of slope is presented in mathematics textbooks of middle school. For this study, we analyzed the types of slope concepts in the textbooks. In particular, we analyzed motivation activity, definition, examples of slope in them and used a concept framework of slope by Stump(1999, 2001), Moore-Russo, Connor & Rugg (2011). As a result, it was shown that middle school mathematics textbooks use the types of slope concepts to be biased when explaining the slope or presenting the slope problems. In addition, the real contexts of slope is poorly presented, and the concept types change from visual aspect to analytical aspect in the processes. This study provides suggestions on how to present the slope concepts in mathematics curriculum and middle school textbooks.

• Journal of Digital Contents Society
• /
• v.10 no.2
• /
• pp.269-278
• /
• 2009

This study was conducted to provide standards for the development of contents and systems for digital textbooks by examining the learners' satisfaction from digital textbooks, which are now being distributed to schools, in terms of ubiquitous learning, and by verifying the moderation effect of learners' computer self efficacy and digital textbook usage. SPSS win 13.0 was used for technical statistics, Cronbach's $\alpha$ coefficient calculation and correlation analysis for empirical analysis, and the MMR (moderated multiple regression) analysis was conducted for the hypothesis test. The following principal results were obtained from the hypothesis tests. First, the ubiquitous learning features had direct effects on the learning satisfaction from the digital textbooks. Second, when the ubiquitous learning features had positive effects on the learning satisfaction from digital textbooks, both the computer self efficacy and digital textbook usage reacted with the ubiquitous learning feature and showed moderation effects. These results were statistically significant.

• Journal of Digital Contents Society
• /
• v.16 no.5
• /
• pp.757-766
• /
• 2015

Recent technological advancements, along with an increase in mobile Internet access, have spurred on significant developments in the production of e-textbooks. This case study explored the affordances of an iPad e-textbook through teacher and student experiences in English lessons using observation and interviews. The results showed that English learners and teacher benefited from handy and quick web access and the all-in-one features of the e-textbook (dictionary, hyperlinks, and note-taking functions). However, information oversupply by the e-textbook confused students' learning and both students and teacher pointed out technical difficulties in using the e-textbook. In order to implement English pedagogy with technologies such as iPad e-textbooks, teachers should be equipped with the relevant technical skills and content knowledge in order to assist them in becoming autonomous learners in the digital classroom.

• Journal of the Korean Chemical Society
• /
• v.57 no.3
• /
• pp.398-404
• /
• 2013

In this study, the analogies in the chemistry domain of middle school science textbooks developed under the 2007 revised National Curriculum were analyzed. A total of 235 analogies were found in 27 middle school science textbooks analysed, which means that one analogy per 10 pages was used on average. The number of analogies found in each textbook considerably varied depending on both publishing company and chemistry domain. Functional analogies, verbal and pictorial analogies, analogies with abstract target and concrete analog, enriched analogies, everyday contexts analogies, student-centered analogies, and analogies with low systematicity were frequently used. On presenting the analogies in the textbooks, the term analogy and description about the limitations of the analogies were rarely mentioned. In comparison with the analogies in the science textbooks developed under the 7th National Curriculum, the frequency of analogies per page was increased. There were positive changes in the aspects of representation, extent of mapping and artificiality. No differences, however, were found in the patterns of the other aspects.

• Korean Journal of Construction Engineering and Management
• /
• v.12 no.2
• /
• pp.143-151
• /
• 2011

The process of design management by public client has not performed effectively due to lack of the formal guidelines and procedures in domestic public projects. The purpose of this research is to develop the guidelines and procedures of design management for public clients. The research methodology is to analyze current status of design management process in domestic and overseas cases and to develop the guidelines based on the administrative stages of design process along the project. The guidelines of design management developed by the design stages of pre-contract, contract, and post-contract stages to classify administrative procedures. The outcome of this research is able to be utilized by the public clients and design firms to standardize the process of design management and minimize potential risk during the process of the project.

• Journal of Elementary Mathematics Education in Korea
• /
• v.16 no.1
• /
• pp.21-38
• /
• 2012

In this study, elementary mathematics textbooks from grade 1 to grade 6 of Korea and Yanbian Korean Autonomous Prefecture are compared. This study is limited to number area. In this study, textbooks of Korea are developed according to the 2007 curriculum and published between 2009 and 2011 and textbooks of Yanbian are published between 2009 and 2010. Seven implications for developing Korean textbooks can be drew from Yanbian textbooks as conclusions. First, it is necessary to consider using counters to teach place values. Second, it is necessary to consider reading inequalities in style of one to one correspondence between signs and words. Third, it is necessary to consider mentioning explicitly that it is possible to express the concrete whole which has a continuous quantity as natural number 1. Fourth, it is necessary to consider introducing term of fraction line that separates the numerator and denominator. Fifth, it is necessary to consider mentioning explicitly the properties of the fraction. Sixth, it is necessary to consider broadening examples to use decimals. Seventh, it is necessary to consider stating clearly that it is possible to make an additional place of decimals by adding a zero at the right end of the decimals.