• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 1994.04c
• /
• pp.6-6
• /
• 1994

Har dmaterials such as cemented carbides with or without coated layer, cermets, ceramics and diamond or c-BN high pressure sintered compact are used for cutting tools, wear -resistant parts, rock drilling bits and/or high pressure vessels. These hardmaterials contain not only hard phase, but also second consituent as the element for forming ductile phase and/or sintering aid, and the mechanical properties of each material depend on (1) the amount of the second constituent as well as (2) the grain size of the hard phase. The hardness of each material mainly depends on these two factors. The fracture strength, however, largely depends on other microstructur a1 factors as well as the above two factors. For all hardmaterials, the fracture strength is consider ably affected by (3) the size of microstructur a1 defect which acts as the fracture source. In cemented carbides, the following factors which are generated mainly due to the addition of the second constituent are also important; (4) the variation of the carbon content in the normal phase region free from V-phase and graphite phase, (5) the precipitation of $Co_3$ during heating at about $800^{\circ}C$,(6) the domain size of binder phase, and (7) the formation of ${\beta}$-free layer or Co-rich layer near the surface of sintered compacts. For cemented carbides coated with thin hard substance, the important factors are as follows; (8) the kind of coated substance, (9) the formation of ${\eta}$-phase layer at the interface between coated layer and substrate, (10) the type of residual stress (tension or compression) in the coated layer which depends on the kind of coating method (CVD or PVD), and (11) the properties of the substrate, and (12) the combination, coherency and periodicity of multi-layers. In the lecture, the details of these factors and their effect on the strength will be explained.

• Journal of Digital Convergence
• /
• v.19 no.4
• /
• pp.339-347
• /
• 2021

The purpose was to analyze the trend of sport pedagogy in secondary teacher certification examination based on the secondary teacher qualification criterion in Korea Institute for Curriculum and Evaluation since abolition of multiple-choice questions from 2014 to 2020. The result showed the questions for sport pedagogy were 48 question since 2014, and found 83 sub-questions. The implications are as follows. First, the frequency of sub-questions in sport pedagogy has increased, causing an integrated question. Second, the serious unbalanced issue of questions for examination was presented. Third, dependence on specific domains was excessively high. Fourth, the confusion caused by the overlapped domains with the content knowledge of physical education subject was intensified. Therefore, evaluation factors based on 2016 KICE classification table should be clear and field application questions should be developed.

• Journal of Korean Clinical Nursing Research
• /
• v.29 no.3
• /
• pp.211-222
• /
• 2023

Purpose: This study was conducted to update the existing evidence-based nursing clinical practice guideline for indwelling urinary catheterization (IUC). Methods: The guideline have been revised in 22 steps based on international standards. The quality of the practice guidelines to be used for revision was evaluated using the Appraisal of Guidelines for Research and Evaluation II. The evaluation of the content appropriateness and applicability of the draft recommendations of the revised practice guidelines was performed using the RAND/UCLA Appropriateness Method, a decision-making method developed by the RAND Corporation. Four guidelines were used for the revision. Results: The updated nursing practice guideline for IUC consisted of 9 domains and 134 recommendations. The numbers of recommendations in each domain were: 4 Assessment, 20 Equipment, 11 Catheter insertion, 52 Catheter maintenance, 4 Catheter and drainage bag change, 9 Catheter removal, 22 Complications management, 5 Education and consult, and 7 Hospital support. The recommended grade was 8.2% for A, 38.1% for B, and 53.7% for C. Among these, the major revision was done in 11 recommendations (8.2%). A total of 29 recommendations (21.6%) were newly added. 30 (22.4%) recommendations had minor revisions such as changes or addition for some words or sentences, and 13 (9.7%) recommendations were deleted. Conclusion: Revised nursing practice guideline is expected to serve as an evidence-based practice guideline for IUC in Korea. This guideline will provide health care providers, patients, and caregivers with information to help manage IUC, leading to improved patient outcomes.

• Steel and Composite Structures
• /
• v.51 no.1
• /
• pp.73-91
• /
• 2024

This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with a damaged core and FG wavy CNT-reinforced face sheets. A damage model is introduced to provide an analytical description of an irreversible rheological process that causes the decay of the mechanical properties, in terms of engineering constants. An isotropic damage is considered for the core of the sandwich structure. The classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for the trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. After demonstrating the convergence and accuracy of the method, different parametric studies for laminated trapezoidal structure including carbon nanotubes waviness (0≤w≤1), CNT aspect ratio (0≤AR≤4000), face sheet to core thickness ratio (0.1 ≤ ${\frac{h_f}{h_c}}$ ≤ 0.5), trapezoidal side angles (30° ≤ α, β ≤ 90°) and damaged parameter (0 ≤ D < 1) are carried out. It is explicated that the damaged core and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. Results show that by increasing the values of waviness index (w), normalized natural frequency of the structure decreases, and the straight CNT (w=0) gives the highest frequency. For an overall comprehension on vibration of laminated trapezoidal plates, some selected vibration mode shapes were graphically represented in this study.

• Journal of the Korean Chemical Society
• /
• v.66 no.1
• /
• pp.42-49
• /
• 2022

Many elementary school teachers' lack of scientific knowledge reveal as several problems in teaching science. Thus, elementary school teachers need to improve their scientific knowledge, but there is the limit to improve the teachers' scientific knowledge through activities based on lecture that conducted in process of training and retraining them. Therefore, Improvement for training science teacher to improve scientific knowledge of elementary school teachers would be searched in this study. Depth interview was conducted toward three elementary school teachers, who had conducted action research, to improve content knowledge of material domain within teaching process and elementary school science. Based on result of the interview, difficulty and development that the three teachers were commonly experienced in process of conducting scientific inquiry in action research were analyzed. One of the difficulties of the inquiry were to figure out how the three teachers, who participated in the interview, understand specific concept, what they do not understand, and what they should study more to understand the concept. And there was a circumstance that the teachers did not know how to apply procedural knowledge, which learned explicitly in the process of setting plan for conducting research, into real context. Since there was difference between knowledge that they understand disjunctively and context that observed in real circumstance, they faced difficulty. However, the teachers conducted analysis of topic, planning research, conducting research, discussion of the result by themselves with those difficulties Thus, the teachers mentioned that not only content knowledge had been improved, but understanding of procedural knowledge, which is not intended to improve, had been also improved. Besides, they also mentioned that comprehensive understanding content knowledge, which they already understood, was also helpful. And the teachers suggest that if there were chance to discuss and examine the scientific practices by consisting of group with colleagues rather than conducting it individually it would more efficient studying. Considering their suggestion, direction of training elementary school teachers for improving their scientific knowledge should be improved in a way to understand science concepts based on direct research about context that is generated in circumstance of studying group of the teachers. Consequently, it would contribute to improvement of teaching science by combining teachers' practice and understanding.

• Therapeutic Science for Rehabilitation
• /
• v.9 no.1
• /
• pp.24-44
• /
• 2020

Objective : To develop an occupation-based bilateral upper extremity training protocol that can be effectively applied in a medical setting Methods : The research process using the delphi technique was carried out in 3 stages. The first stage was an open questionnaire development stage, The first draft is prepared through literature review and open questions were developed through preliminary research based on the draft. The second stage was the delphi survey. Based on the responses of the experts obtained through the open Delphi survey, the adequacy of the training protocol was shown on a Likert 5 point scale. The items were edited and deleted, reconstructed by analyzing the mean and standard deviation, stability, convergence degree, consensus, and content validity ratio through the questionnaire. The third step was the completion of the protocol. After discussions between researchers, the finalized protocol contents were reorganized to complete the occupation-based bilateral upper extremity training protocol for medical setting. Results : The final protocol consisted of 9 items across 3 areas in the occupation-based intervention selection domain and 81 items across 4 areas in the bilateral upper extremity training domain, intervention period, and evaluation. Conclusions : This study suggests an evidence-based method that collects the opinions of occupational therapists in order to use occupation-based activities as interventions in a situation that currently sees occupational therapy primarily performed in hospitals. It is also meaningful that the bilateral upper extremity training can be applied effectively in clinical situations by concretely presenting.

• Journal of the Korean Society for information Management
• /
• v.24 no.2
• /
• pp.161-179
• /
• 2007

As increasingly diverse kinds of information materials are available on the Internet, it becomes a challenge to define an adequate level of metadata provision for each different type of material in the context of digital libraries. This study explores issues of metadata provision for a particular type of material, statistical tables. Statistical data always involves numbers and numeric values which should be interpreted with an understanding of underlying concepts and constructs. Because of the unique data characteristics, metadata in the statistical domain is essential not only for finding and discovering relevant data, but also for understanding and using the data found. However, in statistical metadata research, more emphasis has been put on the question of what metadata is necessary for processing the data and less on what metadata should be presented to users. In this study, a case study was conducted to gauge the status of metadata provision for statistical tables on the Internet. The websites of two federal statistical agencies in the United States were selected and a content analysis method was used for that purpose. The result showing insufficient and inconsistent provision of metadata demonstrate the need for more discussions on statistical metadata from the ordinary web users' perspective.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.144-151
• /
• 2019

The purpose of this study was to investigated of the pre service teacher's information availability and concern and perception of coding education for young children. The subjects were 230 pre service teacher attending a A college micro politan city Questionnaires. The collected data were analyzed by ANOVA and Pearson's correlation coefficient analysis with SPSS Program. The results were as follows: First, the pre service teacher's information availability was smart phone usage levels that the most of all and the next was computer usage levels. Concern of coding education for young children that consequence concern was the highest and the next that collaboration concern, personal concern, information concern, refocusing concern, management concern. The other side unconcerned was most of least. Perception of coding education for young children that necessity perception, content perception, environmental perception was the over of mean. But operational perception was the low. Second, The information awareness, smart phone usage levels as each domain of information ability, usefulness of use was positively associated with Personal concern. But the information ability were negatively correlated with management concern. The information awareness was associated with necessity of coding education. The useful and ease of use of education were positively associated with content coding education.

• Journal of The Korean Association For Science Education
• /
• v.16 no.1
• /
• pp.61-76
• /
• 1996

The purpose of this study was to apply the instructional strategies for conceptual change prescribed by Posner et al(1982) to the astronomic content domain taught in the elementary and middle school and to analyze the characteristics of students' knowledge revealed in the test before, during and after the instruction. Also, it was to investigate the intercorrelation of cognitive levels, spatial ability and science achievement. The major findings of this study are as follows: 1. Students had a great variety of misconceptions related to the motion of the moon before the instruction, that is, the phases, the names of phases and the cause of changing phases by the moon's orbit about the earth, the moon's appearance and location at the given time, the relative positions of earth, moon and sun during a lunar eclipse, the cause that a full moon is not at the line of node once a month. In the analysis of students' responses concerning the cause of changing phases of the moon and a lunar eclipse, the results indicate that the great majority of students had rote learning rather than meaningful learning in the middle school. 2. Students' reponses during the instruction concerning the changing phases of the moon and the predictive knowledge about the motions of the earth and the moon were analyzed. 1) According to the results of the test given before and after experiment, after discussion, achievement score of the whole of subjects and groups in both preformal and formal cognitive levels appeared to increase linearly. 2) There was no statistically significant differences of achievement scores before and after experiment, after discussion between preformal group and formal group in cognitive levels. 3. Distribution of achievement scores according to the whole of subjects and groups in preformal and formal cognitive levels shows that there was a statistically significant difference between pretest and posttest. 4. Types of conceptual changes concerning the cause of changing phases of the moon that occurred from pretest to posttest were classified as accommodation, incomplete accommodation, assimilation, no change and no model. Six of the seven students starting instruction with alternative frameworks didn't sustain those alternative models throughout instruction. Five of these six students accommodated completely and the last one partially. Seventy-nine percentage of students taking instruction with fragmental models assimilated correct propositions at the end of the instruction. These results suggest that conceptual change model prescribed by Posner et al(1982) has promised the meaningful learning to students taking with fragmental models, especially in cases where students with misconception enter instruction. 5. High correlation between achievement score of simple-recall items and that of written items in pretest and posttest indicates that the higher students got the score in simple-recall items the better they also performed in written items. However, there was no statistically significant differences among cognitive levels, spatial ability and science achievement in the whole of subjects and groups according to the cognitive levels.

• Journal of Broadcast Engineering
• /
• v.14 no.4
• /
• pp.463-474
• /
• 2009

By employing the subscriber concept in broadcasting services, IPTV (Internet Protocol Television) operators provide various grades of services to subscribers based on the billing level of the subscribers. With the income from subscribers for a basis, IPTV operators plan to provide high quality services. Since Web browser-based IPTV provides T-commerce and E-commerce services as well as television services, users may frequently visit other service domains to buy goods or content. To provide the user with charged or private services, these service domains request authentication of user. The existing authentication system is not appropriate for the IPTV service environment because the environment unavoidably forces the user to cross from one authentication-based service domain to another. Single sign-on provides a user with transparent authentication services by enabling an authenticated user to move between authentication-based service domains without any re-authentication. Like this distributed environment, since the IPTV service environment also provides a variety of authentication-based services, transparent authentication service needs to be provided to subscribers who want to access charged or private services. In this paper, we propose a new user authentication scheme for the IPTV environment. This scheme integrates the Security Assertion Markup Language (SAML), which is a standard for XML-based single sign on. We validate this scheme using a simple use case scenario.