• Journal of Elementary Mathematics Education in Korea
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• v.5 no.1
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• pp.99-120
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• 2001

The purpose of this thesis is to find the guiding direction of mathematical communication in lower grade students of elementary school and to present a new direction about the effect of using concrete material in communication. It is expected that mathematical communication increases when concrete material is used for the students of the lower grades, who are in concrete operational period. Therefore, this study ai s to investigate what characteristics there are in mathematical communication of second grade students and what effect concrete materials have on mathematical communication and learning. The analysis of the teaching record shows that the second grade students use alternative terms in the process of communication since they are not familiar with mathematical symbols or terms, which is a characteristic of communication in a mathematics class in which concrete material is used. In the process of teaming the students apply their living experiences to their teaming. Since a small number of students lead class, the interaction between students is also led by them. The direction of communication in a small group is not centered around solution of a problem, and most students show a more interest in finding answers than in the process of learning. The effect that concrete material has on communication plays an important role in promoting students' speaking activity; it allows students to identify and correct their errors more easily. It also makes students' activities more predictable, and it increases a small group activities through the medium of concrete material. However, it was also noticed that students' listening activities are not appropriately developed since they do not pay attention to a teacher who uses concrete material. The effects that concrete material has on mathematics class can be summarized as follows. Concrete material promotes students' participation in class by triggering their interest of learning of mathematics and helps them to understand the course of learning. It also helps the teaming and formation of concepts for children of low academic performance. And it makes a phased learning possible according to students' ability to use concrete material and to solve a problem. Based upon the results above mentioned, the use of concrete material is absolutely needed in mathematics classes of lower grade elementary school students since it increases communication and gives much influence on mathematics learning. Therefore, teachers need to develop teaching or learning method which can help increase communication, considering the characteristics of students' communication.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.39-46
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• 2022

The rainfall characteristics such as heavy rains are changing differently from the past, and uncertainties are also greatly increasing due to climate change. In addition, urban development and population concentration are aggravating flood damage. Since the causes of urban inundation are generally complex, it is very important to establish an appropriate flood prevention plan. Thus, the government in Korea is establishing standards for disaster prevention performance for each local government. Since the concept of the disaster prevention performance target was first presented in 2010, the setting standards have changed several times, but the overall technology, methodology, and procedures have been maintained. Therefore, in this study, studies and technologies related to urban disaster prevention performance were reviewed using the scientometric analysis method to review them. This analysis is a method of identifying trends in the field and deriving new knowledge and information based on data such as papers and literature. In this study, papers related to the disaster prevention performance of the Web of Science for the last 30 years from 1990 to 2021 were collected. Citespace, scientometric software, was used to identify authors, research institutes, countries, and research trends, including citation analysis. As a result of the analysis, consideration factors such as the the concept of asset evaluation were identified when making decisions related to urban disaster prevention performance. In the future, it is expected that prevention performance standards and procedures can be upgraded if the keywords are specified and the review of each technology is conducted.

• Journal of the Korean School Mathematics Society
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• v.12 no.3
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• pp.247-265
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• 2009

In the 21C information-based society, there is an increasing demand for emphasizing communication in mathematics education. Therefore the purpose of this study was to research how properties of communication among small group members varied by mathematical problem types. 8 fourth-graders with different academic achievements in a classroom were divided into two heterogenous small groups, four children in each group, in order to carry out a descriptive and interpretive case study. 4 types of problems were developed in the concepts and the operations of fractions and decimals. Each group solved four types of problems five times, the process of which was recorded and copied by a camcorder for analysis, among with personal and group activity journals and the researcher's observations. The following results have been drawn from this study. First, students showed simple mathematical communication in conceptual or procedural problems which require the low level of cognitive demand. However, they made high participation in mathematical communication for atypical problems. Second, even participation by group members was found for all of types of problems. However, there was active communication in the form of error revision and complementation in atypical problems. Third, natural or receptive agreement types with the mathematical agreement process were mainly found for conceptual or procedural problems. But there were various types of agreement, including receptive, disputable, and refined agreement in atypical problems.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.6
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• pp.279-290
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• 2013

In digital forensics log files have been stored as a form of large data for the purpose of tracing users' past behaviors. It is difficult for investigators to manually analysis the large log data without clues. In this paper, we propose a text mining technique for extracting intrusion logs from a large log set to recommend reliable evidences to investigators. In the training stage, the proposed method extracts intrusion association words from a training log set by using Apriori algorithm after preprocessing and the probability of intrusion for association words are computed by combining support and confidence. Robinson's method of computing confidences for filtering spam mails is applied to extracting intrusion logs in the proposed method. As the results, the association word knowledge base is constructed by including the weights of the probability of intrusion for association words to improve the accuracy. In the test stage, the probability of intrusion logs and the probability of normal logs in a test log set are computed by Fisher's inverse chi-square classification algorithm based on the association word knowledge base respectively and intrusion logs are extracted from combining the results. Then, the intrusion logs are recommended to investigators. The proposed method uses a training method of clearly analyzing the meaning of data from an unstructured large log data. As the results, it complements the problem of reduction in accuracy caused by data ambiguity. In addition, the proposed method recommends intrusion logs by using Fisher's inverse chi-square classification algorithm. So, it reduces the rate of false positive(FP) and decreases in laborious effort to extract evidences manually.

• Journal of Navigation and Port Research
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• v.41 no.6
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• pp.373-380
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• 2017

Operational errors caused by human factors, which is the major cause of marine accidents, include lack of knowledge, misunderstanding knowledge, and inadequate procedures. Recently, the type of propulsion mounted on KCG cutters has been diversified. In particular, the water jet propulsion unit, which was mainly installed in small boats, have been gradually expanded to medium and large size Coast Guard cutters, reaching 50% of the total. Axes types are divided into 2 to 4, and the bucket types are divided into Double Reverse Bucket(DRB) and Single Reverse Bucket(SRB); in these, the backward and steering control methods are completely different. Diversification of these operating systems can increase factors causing human error by the ships' operators. However, there is a lack of research on the maneuvering methods, considering the inherent active characteristics of each type of water jet. In this paper, we analyze the sideway method suitable for the condition of Coast Guard Exclusive wharf without assistance, based on the astern performance of each type. Then, a ship handling simulator was used for the experiment; they compared and verified through interviews of captains.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.6
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• pp.23-32
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• 1996

차량에서 엔진은 가장 큰 질량 집중체(concentrated mass)이다. 만약 엔진이 적절하게 구속되지 않거나 절연되어 있지 않으면, 차체에 진동을 일으키는 원인이 된다. 엔진은 다양한 진동 교란을 받는데 엔진 마운트는 이러한 모든 것들을 고립시키는 역할을 해야 하며, 엔진은 정적인 장착 하중에 대한 지지와 전후, 좌우 및 수직 방향의 운동에 대해 적절한 강성을 가져야 한다. 또한 정숙성을 향상시키기 위해서는 엔진 마운트의 재료인 고무의 강성계수를 낮추는 것이 필요한데 이는 일반적으로 내구성의 저하를 가져온다. 따라서 개발과정에서 강성계수를 낮추는 변경을 하면 부품의 내구성을 보정함에 따르는 재평가 또한 필요하게 된다. 엔진 마운트에 쓰이는 고무부품의 해석은 엔진 마운트 시스템에 대한 진동 해석 및 내구수명의 예측과 병행해야 하며, 진동해석으로부터 얻은 하중 지지 능력 등의 모든 요구 특성을 만족하기 위해서는 고무 재료의 특성에 대한 지식, 엔진 마운트의 장착 위치에 대한 결정 능력과 함께 주어진 조건에 대한 형상의 최적 설계 능력 등이 요구된다. 본 연구에서는 기본적인 형상을 파라미터화하여 엔진 마운트의 형상을 최적화 하는 절차를 제안하였다. 현재 승용차에 널리 사용되고 있는 부시형(bush type) 엔진마운트를 적용 모델로 선택하였으며, 엔진 마운트의 기본적인 형상을 몇개의 파라미터를 사용하여 정의하고 설계 사양으로 주어지는 강성값과 각 파라미터들의 조합으로 구성되는 형상이 갖는 강성값의 차이가 최소가 되도록 파라미터 값들을 최적화하였다. 최적화된 파라미터 값들로 구성되는 형상을 내구 성능, 성형성등을 고려하여 최종 형상으로 결정한다. 내구성능의 예측은 금속부품의 내구수명 예측에 널리 이용되고 있는 방법이 방진 고무부품의 경우에도 적용 가능한지를 검토하고, 방진 고무부품에도 일반적으로 적용될수 있는 내구수명 예측방안의 개발 가능성을 타진해 보았다. 본 연구의 목표는 시제품을 제작하기 이전에 설계된 부품에 대한 스프링 상수 및 내구특성을 체계적으로 규명하여 제품 시험의 횟수를 줄이고, 보다 정밀한 제품을 제작할 수 있도록 하기 위한 것이다.

• Journal of The Korean Association For Science Education
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• v.25 no.5
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• pp.595-602
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• 2005

The purpose of this study was to test effects of the Triple Abduction Model (TAM) for improving the skills of scientific hypothesis generation in science learning. Twenty-six students were selected for the TAM group and 27 others were selected for a traditional group from one high school. Researchers developed and administered 10 TAM and traditional-style activities. The degree of hypothesis explanation was evaluated during the experimental treatment. Each Subjects' ability in scientific hypothesis generation was assessed by the Science Knowledge Generation Test A and B. Test A was used as a protest and B for a posttest. The results of this study revealed that the degree of hypothesis explanation of TAM was significantly higher than the degree of the traditional group, and the mean of the TAM group was equal to the mean of traditional group on the pretest. Additionally, the mean of the TAM group was significantly higher than the mean of the control group on the posttest. Therefore, instruction with TAM was more effective than the instruction using traditionals method for increasing students' hypothesis generation skills.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.9
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• pp.1271-1276
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• 2018

The CPTPP(Comprehensive and Progressive Agreement for Trans-Pacific Partnership) is a large-scale free trade agreement(FTA) in the Asia-Pacific region involving 11 remaining countries(Japan, Australia, New Zealand, Canada, Mexico, Chile, Peru, Singapore, Vietnam, Malaysia and Brunei) since the withdrawal of the US TPP in January 2017, Although the economic size is smaller than the TPP, the CPTPP has 12.9% of the world GDP and 14.9% of the trade volume, meaning that another mega FTA is born. Local economic experts believe that Vietnam's stable economic growth rate and the CPTPP agreement will have a positive impact on Vietnam's stock market and M&A market in 2018. The experts usually expect it will be come into force in 2018 and not later than 2019. The CPTPP is also very likely to enter into force in 2019 with the aggressive attitude of the member countries, simplifying the entry into force of the agreement.

• Korean Journal of Construction Engineering and Management
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• v.11 no.3
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• pp.3-12
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• 2010

Recently, workers on construction sites can hardly understand their tasks and the process of the tasks because the construction projects are becoming large and complex. Due to the complexity, workers need a tool that can help them understand their works and some paper-based manuals exist to support them. However, the existing paperbased manuals are not actively used by workers due to the low credibility of information on the manual. In particular, paper-based manual can not be updated frequently because those manuals have to be manually updated by experts. Thus, the credibility of information is decreased and the decrease let the users distrust information of the paper-based manual. Therefore, this research analyzed the feature of wiki-based system and suggested an wiki-based IETM(Interactive Electronic Technical Manual) system model that can be modified by users, and then conducted a survey through a prototype based on urban regeneration project. The result of the survey indicated that wikibased IETM can improve the stakeholder communication by reinforcing the process of creating knowledge as well as knowledge itself.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.33-38
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• 2020

Problem development is important to Problem-Based Learning (PBL) and is key to the creativity and problem-solving skills of successful learners. The purpose of this study is to have PBL classes that effectively materialize problem development stages, and to develop learning using problems suitable for elementary school English Science classes. In this study, the steps for developing the problems are identifying educational content, identifying learners' characteristics, discovering problems, setting up roles and situations, and writing problems. Based on these steps, five PBL problems were developed by selecting a subject suitable for the PBL method of an English Science class, which is one of the English curriculums in elementary schools. Creative thinking, problem-solving skills, presentation skills, confidence, self-directed learning, cooperation, and communication skills are required in the rapidly changing society of the 21st century, rather than teacher-centered instruction, acquiring knowledge for correct answers only, and uniform assessments, which still take place in many English education settings. Therefore, developing problems suitable for PBL learning should be continuously studied.