• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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• pp.64-64
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• 2003

Objectives: Patient dose verification is clinically the most important parts in the treatment delivery of radiation therapy. The three dimensional(3D) reconstruction of dose distribution delivered to target volume helps to verify patient dose and determine the physical characteristics of beams used in intensity modulated radiation therapy(IMRT). We present Beam Intensity Scanner(BInS) system for the pre treatment dosimetric verification of two dimensional photon intensity. The BInS is a radiation detector with a custom made software for relative dose conversion of fluorescence signals from scintillator. Methods: This scintillator is fabricated by phosphor Gadolinium Oxysulphide and is used to produce fluorescence from the irradiation of 6MV photons on a Varian Clinac 21EX. The digitized fluoroscopic signals obtained by digital video camera will be processed by our custom made software to reproduce 3D relative dose distribution. For the intensity modulated beam(IMB), the BInS calculates absorbed dose in absolute beam fluence, which are used for the patient dose distribution. Results: Using BInS, we performed various measurements related to IMRT and found the followings: (1) The 3D dose profiles of the IMBs measured by the BInS demonstrate good agreement with radiographic film, pin type ionization chamber and Monte Carlo simulation. (2) The delivered beam intensity is altered by the mechanical and dosimetric properties of the collimating of dynamic and/or static MLC system. This is mostly due to leaf transmission, leaf penumbra, scattered photons from the round edges of leaves, and geometry of leaf. (3) The delivered dose depends on the operational detail of how to make multileaf opening. Conclusions: These phenomena result in a fluence distribution that can be substantially different from the initial and calculative intensity modulation and therefore, should be taken into account by the treatment planing for accurate dose calculations delivered to the target volume in IMRT.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.34-38
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• 1995

Using a 3-D finite element method (FEM), the biomechanical characteristics of a threaded truncated acetabular component and a porous coated hemispherical acetabular component were studied. The Von-Mises stress/strain patterns in the acetabulum reconstructed with these two different types of cementless acetabular cups were investigated. The geometry and dimensions of human hemi-pelvis used in the present shape modeling for finite element analysis were scanned with a 3-D laser scanner(TDS-9000, Cyberware, USA). The scanned data was numerically handled with a shape modelling software 'Pro-Engineer'. Using 19836, 16853 tetrahedral elements, respectively, the stress and displacement field of the acetabulum reconstructed with the two different types of the acetabular components were computed. While the hemi-sphere component was found to show a relatively similar stress/strain patterns to those in the normal hip, the results with the threaded cup showed a considerably different patterns from those in the normal condition. Several regions in cancellous bone near the threads and the edge of the truncated cup was found to be overstressed, especially in the superior-lateral part of the acetabulum. It was postulated that the excessive reaming-out of subchondral bone layer when the truncated cup was used can cause the presence of these overstressed regions of cancellous bone. This theoretical prediction for the implanted acetabulum appeared to consistent with the pathological observation of proximal/medial migration of the threaded truncated acetabular prostheses in the previous publications.

• 한국멀티미디어학회논문지
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• 제3권5호
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• pp.542-549
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• 2000

본 논문에서는 곡선 그리드상의 2차원 플로우를 분석하고 시각화하기 위한 다해상도 모형을 제안한다. 다해상도 분석은 여러 상세 단계에서 윤곽을 나타내고 분석하는 매우 유용한 도구이다. 일반적으로 벡터 필드의 데이터는 매우 크고 복잡하기 때문에 벡터 필드 시각화에 다해상도 분석을 적용하는 것은 매우 유용하다. 낮은 해상도에서의 근사 값을 사용하면 벡터필드 위상의 전체적인 개요를 짧은 시간 안에 파악할 수 있다. 부분 합성은 사용자가 관심 있는 부분만 합성함으로써 효과적으로 화대 또는 축소할 수 있게 해준다. 이 새로운 모형은 네스트된 곡선 그리드 영역 상에 구분 적으로 정의된 함수의 네스트된 공간에 기초를 두고 있다. 네스트된 영역은 안쪽 경계선의 원래 기하학적 형상을 유지하기 위해 사용된다. 본 논문에서는 이러한 영역 위에서 Haar 웨이브릿에 대한 정제 방정식과 합성 방정식을 제안하고 예제들을 보여준다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.161-162
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• 1997

It is very useful to perform the surgery simulation before implanting TAH(Total Artificial Heart} in a patient. The space of chest and the shape of vessels are different from patient to patient. So, It is desirable to customize a TAH design to the anatomy structure of a patient. Several studies are performed to visualize and explain the 3D structure of heart. These studies are performed using 2-dimensional ref or mated images and simple measurement. Anatomy structure of a human heart is not so simple. It is 4dimensional structure ; 3-dimensional plus time, heart beating. 3-dimensional reconstruction schemes of medical images developed for about 10 years are usually categorized into two types of rendering technique ; surface rendering and volume rendering. Volume rendering is preferable in medical image processing field because this technique can be applied without considering the complexity of geometry and change of field of interest. The usable space in the chest of patient can be measured by 3D volume matching of patient trunk and TAH model. This space changes with time. In this research we have developed the 4-dimensional volume match program of patient and TAH model. 3-dimensional rendered set of volumes along time were used to simulate TAH fitting trial. The quantitative measurement from this simulation could be applied to customize TAH design.

• 한국학교수학회논문집
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• 제10권1호
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• pp.129-148
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• 2007

최근의 수학교육 개혁은 교육과정의 개발이나 평가의 변화에 국한하지 않고, 교사의 학습이나 전문성 신장을 위한 다각적인 노력을 기울이고 있다. 이와 관련하여 가장 저변에 깔려 있는 요소 중의 하나는 가르치는 내용과 방법을 망라한 교수법적 내용지식(Pedagogical Content Knowledge [PCK])이라고 할 수 있다. 본 연구는 초등 교사의 PCK 정립을 위해서 수학과 내용 전반에 걸쳐서 핵심적인 학습 주제를 선정하여 종합적이고 체계적인 교수 학습 자료를 개발한 것이다. 본 논문에서는 이 중에서 비와 비율 주제와 관련하여 수학 내용에 대한 지식, 교수법에 대한 지식, 학생들의 수학적 이해 및 학습에 대한 지식, 교육과정 및 교과용 도서 분석, 교과서 재구성 및 적용으로 나누어 개발된 사례를 제시하였다.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권2호
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• pp.93-110
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• 2018

One of the biggest changes in the 2015 revised mathematics curriculum is shifting to the second year of middle school in Pythagorean theorem. In this study, the following subjects were studied. First, Pythagoras theorem analyzed the expected problems caused by the shift to the second year middle school. Secondly, we have researched the reconstruction method to solve these problems. The results of this study are as follows. First, there are many different ways to deal with Pythagorean theorem in many countries around the world. In most countries, it was dealt with in 7th grade, but Japan was dealing with 9th grade, and the United States was dealing with 7th, 8th and 9th grade. Second, we derived meaningful implications for the curriculum of Korea from various cases of various countries. The first implication is that the Pythagorean theorem is a content element that can be learned anywhere in the 7th, 8th, and 9th grade. Second, there is one prerequisite before learning Pythagorean theorem, which is learning about the square root. Third, the square roots must be learned before learning Pythagorean theorem. Optimal positions are to be placed in the eighth grade 'rational and cyclic minority' unit. Third, Pythagorean theorem itself is important, but its use is more important. The achievement criteria for the use of Pythagorean theorem should not be erased. In the 9th grade 'Numbers and Calculations' unit, after learning arithmetic calculations including square roots, we propose to reconstruct the square root and the utilization subfields of Pythagorean theorem.

• 패션비즈니스
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• 제19권5호
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• pp.1-16
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• 2015

The appearances and geometry structures of knitted fabrics have important effects on their functions as textile fabrics. Structural design of the woven fabric, prior to the manufacturing processes in the weaving mill, often leads to a similar predictable appearance in the final outcome with the corresponding weave design. The increase of the employment of elastic textile yarns in knitting fabrics for comfort stretch or outdoor sports wear knit products has, however, resulted in difficulties in predicting the final appearance of the knit structure design. Due to the stretchability and exceptional recovery behavior of the elastic yarns such as polyurethane elastomeric yarns, the appearance of the final product often differs from the initial knit design. At textile CAD program for preparing tricot knit designs has been employed in this study to predict the two dimensional appearance of the design. The similarities between the designs and corresponding knit products seem to be acceptable for the two-dimensional textile CAD program in this study. However, when elastomeric yarns are partially employed in the polyester filament tricot product, a considerable amount of departure from the design is apparent due to the constriction and/or deformation of property differences in the elastomeric yarns and polyester filament yarns. Therefore, another purpose of this study is to measure the departure of the final tricot product from the initial tricot design, especially in the case employing elastomeric yarns in the knit structure together with regular polyester filament yarns. For measuring the three-dimensional departure, a 3D scanning system has been used for the mesh reconstruction of the fabric specimen. Hopefully, the result from this study will be used as a guide to modify and improve the current textile CAD program proposed for the two-dimensional simulation of the tricot.

• 한국운동역학회지
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• 제13권1호
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• pp.13-21
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• 2003

The purpose of this study is (a) to estimate effective moment arms of quadriceps forces and (b) to compare the $d_e$ between the ACL-reconstructed and uninjured knees from the same individual. One female (20 yrs old, 2 yrs post-op, hamstring tendon autograft) and two males (22 yrs old, 2 yrs post-op; 28 yrs old, 4 yrs post-op; Patellar tendon autografts for both). Sagittal view radiographs were obtained for 6-7 different angles $(range\;5^{\circ}-110^{\circ})$ from each knee. The do was determined by the method of Chow et al. (1999a). The results showed that the maximum de values ranged from 4.61 to 5.59cm and 4.59 to 4.89cm for the ACL-reconstructed and uninjured knees, respectively. The maximum $d_e$ occurred between $35^{\circ}\;and\;50^{\circ}\;and\;20^{\circ}\;and\;50^{\circ}$ for the ACL-reconstructed and uninjured knees, respectively. The minimum do values ranged from 4.12 to 4.35 cm and 3.12 to 3.63cm for the ACL-reconstructed and uninjured knees, respectively. The effective moment arm of the knee extensor affects the loads on knee ligaments during knee-extension exercises. Because apparent differences in the moment arm of the quadriceps in different participants, it is very important to use personalized knee joint geometry for the computation of knee joint force. In the present study, no noticeable bilateral difference was found in the male subjects. However, apparent bilateral differences in de were observed in the female subject. This suggests that the effects of ACL reconstruction surgery on patellar mechanism deserve further investigation.

• 방사선산업학회지
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• 제5권4호
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• pp.325-330
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• 2011

To predict the details of flow in industrial process unit, single photon emission computed tomography (SPECT) is a promising technique. Recently, industrial SPECT based on medical system has developed by researchers of the Korea Atomic Energy Research Institute (KAERI) and Hanyang University. In the present study, to confirm the effect of the number of detectors on image quality, and determine the optimal number of detectors in industrial SPECT, industrial SPECT system with various geometries were evaluated by the Monte Carlo simulation. CsI(Tl) detectors ($12mm{\times}12mm{\times}20mm$) with collimators (the geometric resolution of collimator $R_g$ was 4 cm at the center of the 30 cm diameter cylindrical vessel object) were modeled in a hexagonal array, and the point sources of $^{99m}Tc$, $^{68}Ga$, and $^{137}Cs$ were simulated at the center of the cylindrical vessel object using the MCNPX code. Then, the reconstruction images of each geometry were reconstructed using the expectation maximization (EM) algorithm. In this study, the reciprocity theorem was used to improve computation time required for system matrix of the EM algorithm. The result shows that the resolution of the reconstructed image was significantly improved by increasing the number of detectors in industrial SPECT system and more than 60 detectors will be required for the resolution of the reconstructed image.

• 정보처리학회논문지A
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• 제15A권3호
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• pp.141-149
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• 2008

본 연구에서는 설계모델과 주물 응고의 유한차분법 기반 해석결과를 결합하여 가시화하는 새로운 방법을 제안하고 VR 디스플레이를 도입하여 입체 가시화함으로써 보다 효과적인 분석작업 환경을 제공한다. 먼저 기존 해석 소프트웨어를 사용하여 얻어진 응고해석 결과를 사각형 메쉬모델로 복원하여 복원모델의 모든 정점의 색이 해당 위치의 온도수치를 표현하도록 한다. 다음으로 설계모델의 모든 정점에 대해 가장 가까운 복원모델의 정점을 탐색함으로써 두 모델을 대응하고 대응점의 색을 설계모델 정점에 지정한다. 이때 설계 모델은 최소의 정점으로 모델의 형상이 이루어져 있어 정점의 분포가 복원모델에 비해 균일하지 않으므로 특정 임계값을 설정하여 삼각형 변의 길이가 이보다 큰 경우 정점을 추가함으로써 형태를 유지하는 메쉬 분할을 수행한다. 구현된 시스템은 설계모델 상에서 응고해석 데이터를 가시화함으로써 사용자가 분석객체 세부영역의 정확한 기하정보를 파악할 수 있으며 VR 디스플레이를 통해 실감나는 작업환경을 제공함으로써 보다 빠르고 효과적으로 문제발생여부를 판단할 수 있다.