• Journal of Gifted/Talented Education
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• v.14 no.4
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• pp.71-91
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• 2004

For the education of scientifically gifted high-school students in the field of relativity, we have executed a research on the understanding of relativistic concepts through the case study of its students of Busan Science Academy appointed as a high school for the gifted education in science. We showed the analysis of the changes in students, understanding in the field of (special) relativity and their possible causes. The comparison of the pre-test and the post-test tends to support that the students attained better understanding through the instruction of relativity. Students' understanding and misconception of relativistic concepts were also investigated through the case study. The students showed low degree of understanding in the validity of the principle of relativity, the influence of the constancy of the speed of light on the classical physics, etc. It seems that the analysis of these concepts of insufficient understanding can make a contribution to designing the education of relativity for scientifically gifted students.

• The Journal of Korean Association of Computer Education
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• v.10 no.6
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• pp.11-18
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• 2007

The proposed virtual laboratory system for digital logic circuits is composed of two main sessions, which are concept-learning session and virtual experiment session by virtual digital kit. During concept-learning session the learners can easily understand the important principles in the digital circuits to be performed. In addition, during virtual laboratory session the virtual experiments are performed by assembling and connecting the circuits on the virtual bread board, applying input voltages, making the output measurements, and comparing and transmitting the virtual experimental data. Every activity done during the virtual laboratory session is recorded on database and will be provided with the learners as a preliminary report form including personal information. Thus, the educators may check out the submitted preliminary report to estimate how well the learners understand the circuit operations. Finally, in order to show the validity of our virtual laboratory system we investigated and analysed the damage rate of real experimental equipment during class and assessed student performance on the five quizzes for one semester.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.36-47
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• 2006

The process of dual spin turn maneuver is introduced for attitude acquisition or recovery from flat spin state of a satellite. The physical principle of momentum transfer during dual spin turn is explained clearly. The case studies of special dual spin turn, in addition to the conventional dual spin turn, that are known as an acceptable cases, are performed to investigate the principle of dual spin turn and to provide a physical insight as well as the solution of dual spin turn. This study is done based on case-study simulation, which includes two-state control scheme composed of open-loop maneuver and energy dissipation device. Furthermore, we investigate the stability for the verification of all control cases after implementing two-stage control. We also provide the simulation scenario of flat spin recovery using dual spin turn method as an example.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.15-21
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• 2005

In this study, the utilization of coal-ash and phosphogypsum was considered as the evapotranspiration final landfill cover(ET cover) material. Cover material considered was the mixture of the weathered granite soil, coal-ash and phosphogypsum and so we sequentially performed the leaching test, column test and field model test to investigate the environmental effects of mixtures of coal-ash and phosphogypsum. In the leaching test, all materials had lower heavy metal concentration than the regulated threshold values. The column test and the review of related regulations were carried out to determine the optimum mixing ratio(OMR) and OMR was soil(4):coal-ash(1): phosphogypsum(1) on the volume base, which was applied to field model test. Field model tests were continued from February to June, 2004 in the soil box that was constructed with cement block. It was verified that coal-ash and phospogypsum mixed with soil was safe environmentally and the mixture of both wastes could improve the water retention capacity of cover materials.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.5
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• pp.1063-1070
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• 2021

The development of IT technology emphasizes the importance of training IT professionals, and the need for education for elementary and secondary education as well as adult education for training technical talent is expanding. In particular, information curriculum will be added as an essential course from the 2015 revised curriculum, and IT technology will be understood in the curriculum for elementary and secondary schools and will be required to develop applicability to solve problems based on understanding. Currently, research is under way to integrate IT technologies to provide new services, and if the use of personal information is required in the process, thorough security for the leakage of personal information is pre-empted. It also prevents the identification of personal information in the process of transmitting data to the outside world. In this paper, we propose a training method for elementary school subjects to understand the non-identification process that occurs in the process of transferring data using pipe games so that they can understand the principles of non-identification and develop applications to solve real-life problems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.41-48
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• 2022

This study is a study that designed in-building antennas with improved orientation to improve 5G quality in buildings as 5G is stabilized and more and more traffic is expected to occur in buildings. Instead of applying the forward arrangement of antenna elements, which is the Yagi antenna propagation orientation principle, the antenna design method of vertical arrangement applied to the base station antenna was proposed, and it was confirmed through experiments that antenna orientation increased. According to the experimental results, the directivity did not increase significantly within 10m of the separation distance from the antenna, but the directivity increased by about 3dB at the distance separated by more than 10m. Considering that the wireless environment in the building has various variables such as structure of internal structure, materials such as concrete and glass, closed space, and walls, it is expected that antenna with improved orientation can expand the scope of 5G quality improvement and maintain stable communication service in the building.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.477-486
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• 2009

This paper deals with the strongest static arches with the solid regular polygon cross-section. Both span length and volume of arch are always held constant regardless the shape functions of cross-sectional depth of regular polygon. The normal stresses acting on such arches are calculated when both static vertical and horizontal point loads are subjected. By using the calculating results of stresses, the optimal shapes of strongest static arches are obtained, under which the maximum normal stress become to be minimum. For determining the redundant of such indeterminate arches, the least work theorem is adopted. As the numerical results, the configurations, i.e. section ratios, of the strongest static arches are reported in tables and figures. The results of this study can be utilized in the field of the minimum weight design of the arch structures.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.598-603
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• 2023

Electrochemical ammonia production using catalysts offers a promising alternative to the conventional Haber-Bosch process, allowing for ambient temperature and pressure conditions, environmentally friendly operations, and high-purity ammonia production. In this study, we focus on the nitrogen reduction reactions occurring on the surfaces of ruthenium catalysts, employing first-principles calculations. By modeling reaction pathways for nitrogen reduction on the (0001) and (1000) surfaces of ruthenium, we optimized the reaction structures and predicted favorable pathways for each step. We found that the adsorption configuration of N₂ on each surface significantly influenced subsequent reaction activities. On the (0001) surface of ruthenium, the end-on configuration, where nitrogen molecules adsorb perpendicularly to the surface, exhibited the most favorable N₂ adsorption energy. Similarly, on the (1000) surface, the end-on configuration showed the most stable adsorption energy values. Subsequently, through optimized hydrogen adsorption in both distal and alternating configurations, we theoretically elucidated the complete reaction pathways required for the final desorption of NH₃.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.141-147
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• 2024

The measurement of strain under an electric field has been widely employed to comprehend the fundamental principles of electro-mechanical responses in ferroelectric, piezoelectric, and electrostrictive materials. In particular, understanding the strain properties of piezoelectric materials in response to electrical stimulation is crucial for researching and developing components such as piezoelectric actuators, acoustic devices, and ultrasonic generators. This tutorial paper introduces the components and operational principles of the linear variable differential transducer (LVDT), a widely used displacement measurement device in various industries. Additionally, we present the configuration of an experimental setup using LVDT to measure the strain characteristics of ferroelectric, piezoelectric, or electrostrictive materials under the application of an electric field. This paper includes simple measurement results and analyses obtained through the LVDT experimental setup, providing valuable information on research methods for the electro-mechanical interactions of various materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.91-91
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• 2015

반도체 공정의 발전에 의해 최근 생산되는 메모리 등은 십 수 나노미터까지 좁아진 선 폭을 갖게 되었다. 이러한 이유로, 기존에는 큰 문제를 발생시키지 않던 나노미터 영역의 입자들이 박막 증착 공정과 같은 반도체 제조공정 수율을 저감시키게 되었다. 따라서 오염입자의 유입을 막거나 제어하기 위해 transmission electron microscopy (TEM)나 scanning electron microscopy (SEM)과 같은 전자현미경을 활용한 비 실시간 입자 측정 방법 및 광원을 이용하는 in-situ particle monitor (ISPM) 및 전기적 이동도를 이용한 scanning mobility particle sizer (SMPS) 등 다양한 원리를 이용한 실시간 입자 측정방법이 현재 사용중에 있다. 이 중 진공 내 입자의 수농도를 측정하기 위해 개발된 particle beam mass spectrometer (PBMS) 기술은 박막 증착 공정 등 chemical vapor deposition (CVD) 방법을 이용하는 진공공정에서 활용 가능하여 개발이 진행되어 왔다. 본 연구에서는 PBMS의 한계점인 입자 밀도, 형상 등의 특성분석이 용이하도록 PBMS와 scanning electron microscopy (SEM), 그리고 energy dispersive spectroscopy (EDS) 기술을 결합하여 입자의 직경별 개수농도, 각 입자의 형상 및 성분을 함께 측정 가능하도록 하였다. 협소한 반도체 제조공정 내부 공간에 적용 가능하도록 기존 PBMS 대비 크기 또한 소형화 하였다. 각 구성요소인 공기역학 집속렌즈, electron gun, 편향판, 그리고 패러데이 컵의 설치 및 물리적인 교정을 진행한 후 입자발생장치를 통해 발생시킨 sodium chloride 입자를 상압 입자 측정 및 분류장치인 SMPS 장치를 이용하여 크기별로 분류시켜 압력차를 통해 PBMS로 유입시켜 측정을 진행하였다. 나노입자의 입경분포, 형상 및 성분을 측정결과를 토대로 장치의 측정정확도를 교정하였다. 교정된 장치를 이용하여 실제 박막 증착공정 챔버의 배기라인에서 발생하는 입자의 수농도, 형상 및 성분의 복합특성 측정이 가능하였으며, 최종적으로 실제 공정에 적용가능하도록 장치 교정을 완료하였다.