• Bulletin of the Korean Mathematical Society
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• v.52 no.2
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• pp.377-394
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• 2015

In this paper, we generalize some results about Bertrand curves and Razzaboni surfaces in Euclidean 3-space to the case that the ambient space is Minkowski 3-space. Our discussion is divided into three different cases, i.e., the parent Bertrand curve being timelike, spacelike with timelike principal normal, and spacelike with spacelike principal normal. For each case, first we show that Razzaboni surfaces and their mates are related by a reciprocal transformation; then we give B$\ddot{a}$cklund transformations for Bertrand curves and for Razzaboni surfaces; finally we prove that the reciprocal and B$\ddot{a}$cklund transformations on Razzaboni surfaces commute.

• East Asian mathematical journal
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• v.26 no.4
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• pp.553-579
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• 2010

Geometric education emphasize reasoning ability and spatial sense through development of logical thinking and intuitions in space. Researches about space understanding go along with investigations of space perception ability which is composed of space relationship, space visualization, space direction etc. Especially space visualization is one of the factors which try conclusion with geometric problem solving. But studies about space visualization are limited to middle school geometric education, studies in elementary level haven't been done until now. Namely, discussions about elementary students' space visualization process and ability in plane or space figures is deficient in relation to geometric problem solving. This paper examines these aspects, especially in relation to plane and space problem solving in elementary levels. Firstly we propose the analysis frame to investigate a visualization process for plane problem solving and a visualization ability for space problem solving. Nextly we select 13 elementary students, and observe closely how a visualization process is progress and how a visualization ability is played role in geometric problem solving. Together with these analyses, we propose concrete examples of visualization ability which make a road to geometric problem solving. Through these analysis, this paper aims at deriving various discussions about visualization in geometric problem solving of the elementary mathematics.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.2
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• pp.35-47
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• 2020

The need for communication is emphasized in decision making, design methods and processes for the educational environment that contain new curricula and learning methods. In this study, we tried to find the direction and agenda of learner-centered environment restructuring through the 'user-integrated platform' in which various subjects related to school space environment understand each other's position and overcome the barriers and prejudices of each sector. The project was planned in a 'bottom-up process' method that uncovered the singularities of the previous stage and led the main contents of the next stage. The various subjects who participated in the project shared their own experiences and different positions regarding the school space. At the workshop, the topics of the participating teams were divided into two categories. The teams in the category of the 'school culture and space' insisted innovation of 'the school culture' as a premise for the restructuring of the 'school space', and proposed schools with different interpretations of 'authority and rules of school', 'the meaning of learning and play' and 'the main character of school. The teams in the category of the 'school borders and spaces' focused on 'communication' and proposed schools containing 'emotional care of students', 'borders between schools and villages', 'village community schools', and 'interspace and niche time'. After the workshop, we were able to derive the direction and architectural strategy of the school space restructuring by analyzing the works of the participants. Through this study, we confirmed the possibility of translating user's ideas into the professional domain through careful planning, preparation, facilitation, and analysis in Participatory Design.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2006.06a
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• pp.141-151
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• 2006

최근 U-City와 같은 유비쿼터스 지능 공간 (Ubiquitous Smart Space, USS) 개발이 추진됨에 따라 USS 요구 분석 방법론에 대한 필요성이 커지고 있다. 그러나 SDLC, UML 등과 같은 기존 정보시스템 요구분석 등 개발 방법론은 상황인지 에이전트 시스템 등과 같은 USS 특유의 환경을 고려하지 못해 USS 요구 분석 방법론으로 그래도 적용하기에는 한계가 있다. 따라서 본 논문은 USS 개발을 위한 요구분석 방법론으로서 기존 UML에 상황인지, 에이전트 시스템의 특정을 고려하여 수정된 UML(Amended UML)을 제시하는 것을 목적으로 한다. 이를 위해 본 논문에서는 As-Is Space 와 To-Be Space 로 나누어 요구 분석을 하였다. 또한 본 논문에서 제시한 요구 분석 방법론의 활용가능성을 보이기 위해 국내 쇼핑몰 내 실제 USS 서비스 개발에 적용해 보았다.

• Journal of the Korean Institute of Educational Facilities
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• v.15 no.3
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• pp.52-58
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• 2008

• Journal of Oral Medicine and Pain
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• v.18 no.2
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• pp.43-53
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• 1993

The aim of this study was to investigate the relationship between the presence or absence of anterior tooth contact and the changes in temporomandibular joint space. The study sample consisted of 32symptom-free dental students and 79 craniomandibular disorders patients with unilateral joint dysfunction. The two groups were categorized into control group or experimental group, respectively. Recordings of the number and distribution of occlusal contacts were made by T-Scan system. Transcranial radiographs were taken with using of accurad-100 head positioner. Measured items in transcranial radiographs were anterior, superior, posterior joint space and relative condylar position to deepest position of glenoid folla. According to the presence or absence of anterior tooth contact, each group was subdivided and compared with each other with respect to TM joint space. Data were processed and tested with SPSS/PC + package. The results of the study showed that the joint space in control group were wider than those of experimental group and the difference of the width of joint space was more remarkable in subjects with anterior contact between control group and experimental group. However, in same group whether the presence of anterior tooth contact could hardly affect the difference of the width of joint space. And anterior tooth contact in grouip are more frequent than in experimental group.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1441-1443
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• 1998

In this work, the effects of space charge was analyzed in removal efficiency of pollutant using dielectric barrier discharges. In order to investigate effects of space charge, two dielectrics(XLPE and TR-XLPE) was chosen which are different in space charge distribution. The simultaneously measurement of space charge and discharge current was carried out in XLPE and TR-XLPE with air gap by Pulsed-Electro-Acoustic Method in ac. Also, the removal efficiency is measured by classical ozone generator(von Siemens 1875). From the experimental results, we knew that the space charge distribution affects the discharge patterns. The more space charge is in surface, the quickly discharge initiates and the magnitude of discharge is increased when polarity changes. And these affect the removal efficiency of pollutant.

• Journal of the Korean Institute of Educational Facilities
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• v.28 no.4
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• pp.11-17
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• 2021

This study is aimed at presenting an efficient management plan of user participatory design in a situation where the School Space Innovation Project is in progress. 2 schools that were the targets of the Incheon School Space Innovation Project in 2019 were selected for this, and features such as the physical environment of that classroom, classroom usage plan, and the stepwise outcome of the user participatory design workshop were contemplated. Especially the workshop outcome was compared and analyzed quantitatively, focusing on the actual master plan and zoning plan, in order to identify the feature that opinions of various users are reflected on the actual plan. As a result, the following conclusion could be reached. Firstly, it was confirmed that the expression about the user preferential space influences the classroom usage plan of that classroom. Vague expressions about the whole space held a large majority of the objects for the linguistic expression of the preferential space. The expression mode as limited as the expression of the actions that users want to carry out in the space. On the other hand, when the usage purpose of the classroom was definite, it was confirmed that the demand for furniture·facility is relatively high. Secondly, according to the analysis of zoning for each function, it seems that the stereotype, which is arranged on the basis of the chalkboard at the front of existing classrooms, was applied in the case of the learning zone. However, in cases of other functions, a tendency was identified that the user carries out an image description that reflects the physical features of the space. Sufficient preparation will need to precede for the efficient management of the user participatory design workshop and the acceptance of various opinions. It seems that especially the classroom usage plan, number of workshops, consultation of each step, and the education about the space expression mode affect the master plan.

• The Bulletin of The Korean Astronomical Society
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• v.24 no.2
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• pp.86-86
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• 1999

• Journal of The Korean Astronomical Society
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• v.55 no.4
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• pp.87-97
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• 2022

Polarimetric measurements of the lunar surface from lunar orbit soon will be available via Wide-Field Polarimetric Camera (PolCam) onboard the Korea Pathfinder Lunar Orbiter (KPLO), which is planned to be launched in mid 2022. To provide calibration data for the PolCam, we are conducting speckle polarimetric measurements of the nearside of the Moon from the Earth's ground. It appears that speckle imaging of the Moon for scientific purposes has not been attempted before, and there is need for a procedure to create a "lucky image" from a number of observed speckle images. As a first step of obtaining calibration data for the PolCam from the ground, we search for the best sharpness measure for lunar surfaces. We then calculate the minimum number of speckle images and the number of images to be shift-and-added for higher resolution (sharpness) and signal-to-noise ratio.