• 한국전자통신학회논문지
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• 제8권12호
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• pp.1883-1890
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• 2013

위치 추정 기술 (LDT, Location Detection Technology)은 자원관리 및 통신 서비스의 품질을 향상시키기 위한 무선통신 분야에서 사용되고 있는 LBS(Location Based Service)의 핵심기술 중 하나이다. 이동국(MS, mobile station)의 위치는 세 개의 기지국(BS, base station)들의 좌표와 이동국과 기지국들 사이의 거리에 상응하는 반지름에 기초한 세 개의 원들에 기반한 도래시간(TOA, Time of Arrival)기법을 사용하여 추정된다. 삼각변 측량법을 이용하여 정확한 이동국의 위치를 추정하기 위해서는 세 개의 원들이 한 점에서 만나야 하는데, 이동국과 기지국의 거리를 추정하기 위한 시간지연 개수와 전송 주파수에 따라 원들의 반지름이 증가하여 세 개의 원들이 한 점에서 만나지 못하는 경우들이 발생한다. 반지름이 증가된 세 개의 원들은 여섯 개의 교점을 가지게 되고 이 교점들 중 세 개의 교점들이 특정 이동국의 좌표에 가까이 위치하게 된다. 본 논문에서는 여섯 개의 전체 교점들 중에서 세 개의 내부 교점들을 선택하는 TOA 삼각변 측량법을 위한 최단 거리 알고리즘을 제안한다. 제안된 방법은 여섯 개의 교점들 중 이동국의 좌표와 가장 가까운 세 개의 교점을 선택하고, 선택된 교점들의 평균 좌표를 특정 이동국의 위치로 결정한다. 제안된 알고리즘의 성능은 컴퓨터 시뮬레이션 예를 통해 확인된다.

• 한국측량학회지
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• 제24권3호
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• pp.281-288
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• 2006

최근 비 측정용 디지털 카메라의 화소수가 급증하고, 카메라 단가 또한 저렴해져 문화재 및 시설물의 3차원 공간 측량 등에도 이를 활용할 수 있게 되었다. 그러나 비 측정용 카메라를 측량용으로 활용하기 위해서는, 카메라 자체검정을 통해 내부 표정요소를 정확히 계산해내야 한다. 이를 위해서는 적절한 검정 대상지의 구성 및 촬영계획이 선행되어야 한다. 본 연구에서는 지상기준점 수, 사진의 수, 기준점의 차원(2차원 및 3차원)등의 조건에 따른 카메라 자체 검정 정확도에 대하여 분석하였다. 실험 결과, 근거리 사진측량을 위한 자체검정 대상지 구축 시 수직사진을 포함하는 3장 이상의 사진으로 안정된 정확도를 얻을 수 있음을 알 수 있었고, 3차원 복원을 목적으로 하는 경우, 평면상의 지상기준점 10점으로도 높은 정회도의 결과를 얻을 수 있음을 알 수 있었다.

• 대한원격탐사학회지
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• 제24권3호
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• pp.223-233
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• 2008

In the mid 90's, the U.S. government released images acquired by the first generation of photo reconnaissance satellite missions between 1960 and 1972. The Declassified Intelligent Satellite Photographs (DISP) from the Corona mission are of high quality with an astounding ground resolution of about 2 m. The KH-4A panoramic camera system employed a scan angle of $70^{\circ}$ that produces film strips with a dimension of $55\;mm\;{\times}\;757\;mm$. Since GPS/INS did not exist at the time of data acquisition, the exterior orientation must be established in the traditional way by using control information and the interior orientation of the camera. Detailed information about the camera is not available, however. For reconstructing points in object space from DISP imagery to an accuracy that is comparable to high resolution (a few meters), a precise camera model is essential. This paper is concerned with the derivation of a rigorous mathematical model for the KH-4A/B panoramic camera. The proposed model is compared with generic sensor models, such as affine transformation and rational functions. The paper concludes with experimental results concerning the precision of reconstructed points in object space. The rigorous mathematical panoramic camera model for the KH-4A camera system is based on extended collinearity equations assuming that the satellite trajectory during one scan is smooth and the attitude remains unchanged. As a result, the collinearity equations express the perspective center as a function of the scan time. With the known satellite velocity this will translate into a shift along-track. Therefore, the exterior orientation contains seven parameters to be estimated. The reconstruction of object points can now be performed with the exterior orientation parameters, either by intersecting bundle rays with a known surface or by using the stereoscopic KH-4A arrangement with fore and aft cameras mounted an angle of $30^{\circ}$.

• 대한통합의학회지
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• 제9권1호
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• pp.109-121
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• 2021

Purpose : The first case of coronavirus disease-2019 (COVID-19) disease outbreak in Korea occurred in January 2020, and the cumulative number of confirmed cases by the Central Defense Response Headquarters of the Quality Management Administration as of November 30 was 34,201. Looking at the incidence trend of domestic confirmed cases by age, the incidence rate of COVID-19 in the age group of 20-29 years, which corresponds to college students, was 27.4 %, the highest compared by age group. Considering the current status of the infection rate, universities will become the centers of new COVID-19 cases if face-to-face lectures are recommenced without preparatory measures and analysis of infection prevention (e.g., infection awareness and education for university students). Thus, this study intended to investigate the level of knowledge, educational needs, and preventive behavior performance of college students about COVID-19 and provide basic data for the development of an education program for the prevention of COVID-19 for college students. Methods : This study is a descriptive correlational study aimed to investigate the correlation between knowledge about COVID-19, educational needs, and degree of preventive behavior performance in 407 college students attending one University in Gyeonggi-do. Results : The subjects' knowledge score about COVID-19 was 12.46±1.39 points, average educational needs score was 29.16±3.14 points, and prevention behavior performance survey result was 35.50±3.61 points. Moreover, positive correlation was observed between the knowledge about COVID-19 and educational needs (r=.203, p<.001) and knowledge and preventive behavior performance (r=.140, p=.005). Further, educational needs and preventive behavior performance demonstrated a statistically significant positive relationship (r=.311, p<.001). Conclusion : Therefore, organizing an educational program to acquire accurate knowledge is necessary to make it a habit for college students to practice preventive behavior against COVID-19.

• 한국콘텐츠학회논문지
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• 제12권12호
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• pp.313-320
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• 2012

치과진료실은 다양한 종류의 병원성 미생물에 항상 노출되어 있으며, 환자의 분비물과 에어로졸 형태의 여러 경로를 통해 실내가 오염될 경우 교차감염의 매개 장소가 될 수 있다. 교차감염의 위험이 산재되어 있는 치과진료와 치과진료실에서 교차감염 방지의 주체자는 치과위생사이다. 치과위생사는 임상 전문가로 활동하기 전에 감염방지에 대한 올바른 인식을 가지고 있어야 되며, 이러한 감염방지 인식수준은 임상실습에서부터 영향을 받는다. 이에 감염방지의 인식을 조사하고자 일부 4년제 대학교 치위생학과 교육과정 중 3학년 과정에 임상실습이 정규과목으로 정해져있는 학생 314명을 대상으로 자기기입식 설문조사를 실시하였다. 자료 수집은 2011년 12월 9일부터 2012년 2월 22일까지 수행하였고, 수집된 자료 중 응답이 불성실한 11부의 설문지를 제외한 303부를 SPSS WIN 20.0을 사용하여 최종 분석하였고, 다음과 같은 결론을 얻었다. 감염질환에 관한 인식 영역에서 교내 외 실습 경험군은 감염질환 인지의 중요성 문항에서 4.89점, B형간염 예방접종 의무의 문항에서는 4.65점, B형간염 예방접종 필요성 인식의 문항에서는 4.77점, 문진 실시하여 감염방지를 실천할 수 있는지에 대한 문항에서는 4.71점, 감염방지 교육의 도움에 관한 문항에서는 4.76점으로 가장 높았으며, 유의한 차이를 보였다. 치위생학과 학생들을 위한 체계적이고 다양한 감염방지 교육 프로그램 개발과 학년에 따른 차별적인 교육이 필요하다고 사료된다.

• Structural Engineering and Mechanics
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• 제48권6호
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• pp.775-789
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• 2013

The current paper proposes a boundary element formulation, applicable to 2-D and 3-D elastostatics problems using a unified approach for transformations of the domain integrals into boundary integrals. The method is applicable to linear problems encompassing both finite and infinite multi-region domains allowing non-vanishing body forces. Numerical results agree quite well with the analytical solutions; while the present method offers easy formulation with less numerical efforts in comparison to FEM or some BEM which need interior points to treat arbitrary body forces. It is demonstrated that the method has the potential to have profound impact on engineering design, notably in dam-foundation interaction.

• 한국CDE학회논문집
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• 제12권1호
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• pp.15-26
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• 2007

We have developed a method that enables a user to better understand and enjoy the contents of 3D digital archives, thereby enhancing the user's experience. The system's interactive interface, built using virtual reality technology, enables the user to "walk through" the archives, comparing two or the same content at different points in time. For example, a user can compare the proposed design for a building with the actual building and can compare the states of restoration of a cultural heritage site over time. This ability to perform multilateral comparisons enables the user to clarify the relationship between contents, the influence of one content on another, and the causal relationship between contents. Testing of a prototype system for a 3D digital archive of cultural heritage sites showed that it worked smoothly and that the users could easily operate the navigation system.

• Smart Structures and Systems
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• 제21권4호
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• pp.469-477
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• 2018

This paper presents a numerical solution for the thick cylinders made of functionally graded materials (FGMs) with a constant Poisson's ratio and an arbitrary Young's modulus. We define two fundamental solutions which are derived from an ordinary differential equation under two particular initial boundary conditions. In addition, for the single layer case, we can define the transfer matrix N. The matrix gives a relation between the values of stress and displacement at the interior and exterior points. By using the assumed boundary condition and the transfer matrix, we can obtain the final solution. The transfer matrix method also provides an effective way for the solution of multiply layered cylinder. Finally, a lot of numerical examples are present.

• 소성∙가공
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• 제12권2호
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• pp.142-150
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• 2003

To construct the extrusion die surface, a B-Spline surface scheme based on the cubic B-Spline curve interpolation method is proposed in the present work. The inlet and outlet profiles are described with B-Spline curves by using the centripetal method for uniform parameterization. The interior control points of surface are generated using the derivative characteristics of B-Spline curve. A complete B-Spline surface is constructed by using appropriate coordinate transformation and knot deletion. In the present study, a quantitative measure for the control of surface is suggested by introducing the tangential vector and inclination angles at the inlet and outlet sections. To verify the validity of the proposed method, automatic surface generation is carried out for the various types of extrusion die surface.

• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.127-133
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• 2000

A numerical study of the flow of incompressible fluid in a polar cavity is presented. Irregular grids is proposed by applying the interior division principle to the variables on polar coordinate grid formation. Stability analysis and the pressure correction method of SOLA algorithms were discussed in detail on cylindrical coordinates. The results present that unsteady flow behavior appears over $Re=3{\times}10^4$ on polar cavities but nearly steady state at $Re=10^4$. Furthermore, with increasing Reynolds numbers, vortices behaviors indicate more complicated flow phenomena and more severe temporal fluctuation of total kinetic energy and time variation of velocity components at arbitrary pick-up points are detected in case of $Re=5{\times}10^4$.