• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1223-1229
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• 2004

A variable-gain low-voltage low noise amplifier MMIC operating at 5GHz frequency band is designed and implemented using the ETRI 0.5$\mu\textrm{m}$ GaAs MESFET library process. This low noise amplifier is designed to have the variable gain for adaptive antenna array combined in HIPERLAN/2. The feedback circuit of a resistor and channel resistance controlled by the gate voltage of enhancement MESFET is proposed for the variable-gain low noise amplifier consisted of cascaded two stages. The fabricated variable gain amplifier exhibits 5.5GHz center frequency, 14.7dB small signal gain, 10.6dB input return loss, 10.7dB output return loss, 14.4dB variable gain, and 2.98dB noise figure at V$\_$DD/=1.5V, V$\_$GGl/=0.4V, and V$\_$GG2/=0.5V. This low noise amplifier also shows-19.7dBm input PldB, -10dBm IIP3, 52.6dB SFDR, and 9.5mW power consumption.

• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.221-226
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• 2004

Ant Colony System(ACS) Algorithm is new meta-heuristic for hard combinational optimization problem. It is a population-based approach that uses exploitation of positive feedback as well as greedy search. Recently, various methods and solutions are proposed to solve optimal solution of graph coloring problem that assign to color for adjacency node($v_i, v_j$) that they has not same color. In this paper introducing ANTCOL Algorithm that is method to solve solution by Ant Colony System algorithm that is not method that it is known well as solution of existent graph coloring problem. After introducing ACS algorithm and Assignment Type Problem, show the wav how to apply ACS to solve ATP And compare graph coloring result and execution time when use existent generating functions(ANT_Random, ANT_LF, ANT_SL, ANT_DSATUR, ANT_RLF method) with ANT_XRLF method that use XRLF that apply Randomize to RLF to solve ANTCOL. Also compare graph coloring result and execution time when use method to add re-search to ANT_XRLF(ANT_XRLF_R) with existent generating functions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.21-26
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• 2016

This paper presents a step-down DC-DC buck converter with a CCM/DCM dual-mode function for the internal power stage of portable electronic device. The proposed converter that is operated with a high frequency of 1 MHz consists of a power stage and a control block. The power stage has a power MOS transistor, inductor, capacitor, and feedback resistors for the control loop. The control part has a pulse width modulation (PWM) block, error amplifier, ramp generator, and oscillator. In this paper, an external capacitor for compensation has been replaced with a multiplier equivalent CMOS circuit for area reduction of integrated circuits. In addition, the circuit includes protection block, such as over voltage protection (OVP), under voltage lock out (UVLO), and thermal shutdown (TSD) block. The proposed circuit was designed and verified using a $0.18{\mu}m$ CMOS process parameter by Cadence Spectra circuit design program. The SPICE simulation results showed a peak efficiency of 94.8 %, a ripple voltage of 3.29 mV ripple, and a 1.8 V output voltage with supply voltages ranging from 2.7 to 3.3 V.

• Journal of Information Management
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• v.41 no.4
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• pp.227-249
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• 2010

Scholarly information has increased tremendously according to the development of IT, especially the Internet. However, simultaneously, people have to spend more time and exert more effort because of information overload. There have been many research efforts in the field of expert systems, data mining, and information retrieval, concerning a system that recommends user-expected information items through presumption. Recently, the hybrid system combining a content-based recommendation system and collaborative filtering or combining recommendation systems in other domains has been developed. In this paper we resolved the problem of the current recommendation system and suggested a new system combining collaborative filtering and Naive Bayes Classification. In this way, we resolved the over-specialization problem through collaborative filtering and lack of assessment information or recommendation of new contents through Naive Bayes Classification. For verification, we applied the new model in NDSL's paper service of KISTI, especially papers from journals about Sitology and Electronics, and witnessed high satisfaction from 4 experimental participants.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.360-375
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• 2019

The purpose of this study was to investigate beginning science teachers' perceptions of inquiry-based science instruction using open-ended questionnaire and semi-structured interview. Participants of this study voluntarily set up a goal of inquiry-based science instruction, planned inquiry-based science lessons, and shared and reflected their teaching experiences in their professional learning community for more than a year. Participant teachers recognized students' construction of core scientific concepts through performing scientific inquiry as a goal of science inquiry instruction. Participant teachers indicated that goals of science education such as 'learning scientific core concepts', 'improving students' interest of science', 'improving scientific thinking', and 'understanding the nature of science' can be achieved through students' active engagement in scientific inquiry. Participant teachers recognized not only the importance of teachers' role, but also what roles science teachers should play in order to enable students to perform scientific inquiry. Participant teachers emphasized teachers' roles such as 'identifying core concepts', 'reorganizing science curriculum', 'considering student ability', 'asking questions and providing feedbacks to students', 'explaining scientific concepts', and 'leading students' argumentation.'

• The Mathematical Education
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• v.60 no.1
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• pp.77-110
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• 2021

In this study, a student participation-centered class based on student mathematical thinking as a the meaningful subject was called a student thinking-based math class. And as a way to support these classes, I paid attention to lesson design. For student thinking-based mathematics classes, it is necessary not only to anticipate student thinking and teacher feedback, but also to plan in advance how to properly arrange and connect expected student responses. The student thinking-based lesson design template proposed in this study is a modified three-step(introduction, main topic, summary) lesson design template. The reason for revising the existing design template is that it has limitation that it cannot focus on mathematical thinking. Using the conceptual framework of student thinking-based mathematics lesson as a lens, the difference between the three-step lesson design prepared by pre-service teachers and the students' thinking-based lesson design prepared by the same pre-service teachers was analyzed. As a result of planning lessons using the student thinking-based lesson design, more attention was paid to the cognitive and social engagement of students. In addition, emphasis was placed in the role of teachers as formative facilitator. This study is of significant in that it recognizes the importance of classes focusing on students' mathematical thinking and provides tools to plan math classes based on students' thinking.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.731-741
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• 2020

University campus plans include urban and spatial values and identities that they emphasize. The purpose of this study is to analyze sustainable campus policy, space, and the application to architectural planning, which UBC in Canada pursues independently from a Green Campus Certificate System. Sustainable directions and architectural components are deduced. The results are as follows: 1) the correspondence between the campus plan's goal and architectural implementation is the most important. Thus, the university must build a system for the plan's goal and a strategy to make a sustainable campus. 2) A guideline and system are requested to make many experts in various fields and stakeholders participate in the initial stage through "Design Charrette." 3) A system of virtuous circulation must be built so that feedback can be applied through the real-time comparison and verification of building energy consumption. Another goal of this study is emphasizing the necessity of campus policy and plans based on the "Living Laboratory" concept to make a sustainable city. This study could be meaningful because it supports a basis for triggering the establishment of goals for a sustainable plan and implementation in Korean universities.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.367-372
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• 2022

With the recent advent of the New Normal era, realistic technologies and non-contact technologies are receiving social attention. However, the hair styling field focuses on the direction of the hair itself, individual movements, and modeling, focusing on hair simulation. In order to create an improved practice environment and demand of the times, this study proposed a non-contact hair styling VR system. In the theoretical review, we studied the existing cases of hair cut research. Existing haircut-related research tend to be mainly focused on force-based feedback. Research on the interactive haircut work in the virtual environment as addressed in this paper has not been done yet. VR controllers capable of finger tracking the movements necessary for beauty enable selection, cutting, and rotation of beauty tools, and built a non-contact collaboration environment. As a result, we conducted two experiments for interactive hair cutting in VR. First, it is a haircut operation for synchronization using finger tracking and holding hook animation. We made position correction for accurate motion. Second, it is a real-time interactive cutting operation in a multi-user virtual collaboration environment. This made it possible for instructors and learners to communicate with each other through VR HMD built-in microphones and Photon Voice in non-contact situations.

• Journal of Korea Entertainment Industry Association
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• v.14 no.8
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• pp.501-511
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• 2020

This study investigated and analyzed the contents of writing learning, self-evaluation of writing ability, recognition of writing ability, and recognition of writing education direction to J university students in order to analyze the perception of writing of university students and find ways to improve writing education. Through this, the improvement plan of writing education was discussed. As a result of researching and analyzing the perceptions of university students, college students perceived writing ability as important, and they wanted practical writing classes that received feedback and wrote actual writing rather than theoretical classes. In addition, it was found that they wanted to develop their ability to construct and develop the contents of the article. In order to make writing education a practical competency for college students, theoretical lectures are important, but it is necessary to give enough time and opportunity to write in practice, and to develop customized practical writing. Also, it is necessary to make writing class that students can participate through various teaching methods, and to make writing ability lead to practical competence even after graduation through the method of university graduation certification requirements. This study is meaningful in that it can seek the direction of university writing education through the recognition of college students related to writing.

• Journal of Science Education
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• v.47 no.1
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• pp.1-10
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• 2023

In this study, we investigated the perception of STEAM (science, technology, engineering, arts, and mathematics) education consultants (SEC) about the requirements to achieve actual results and the improvements for STEAM education consulting. Data were collected from teachers who have had previous SEC experience or have extensive experience in STEAM education. First, an open-ended questionnaire was used to conduct a survey on the requirements and improvements for the STEAM education consulting, and items were composed by analyzing the contents of these free responses, and then statistical analysis was performed by asking them to respond on the Likert scale to how much they agreed to each item. As a result of the analysis, the SEC recognized that "formation of consensus between consultants and teachers", "consultant feedback on reflection of previous consulting results" and "encouragement and support for teachers" are appeared to be the most required for STEAM education consulting to achieve actual results. As the improvements of STEAM education consulting, "sharing cases and opinions among consultants", "selection and sharing of consulting best practices", and "development of various consulting types such as open classes" received the highest agreement. Based on these results, a support plan to increase the effectiveness of STEAM consulting was proposed.