Real-Time Simulation of Large Rotational Deformation and Manipulation

최민규,고형석,Choi, Min-Gyu,Ko, Hyeong-Seok Korea Computer Graphics Society 2004 컴퓨터그래픽스학회논문지 Vol.10 No.1

This paper proposes a real-time technique for simulating large rotational deformations. Modal analysis based on a linear strain tensor has been shown to be suitable for real-time simulation, but is accurate only for moderately small deformations. In the present work, we identify the rotational component of an infinitesimal deformation, and extend linear modal analysis to track that component. We then develop a procedure to integrate the small rotations occurring al the nodal points. An interesting feature of our formulation is that it can implement both position and orientation constraints in a straightforward manner. These constraints can be used to interactively manipulate the shape of a deformable solid by dragging/twisting a set of nodes, Experiments show that the proposed technique runs in real-time even for a complex model, and that it can simulate large bending and/or twisting deformations with acceptable realism.

집중호우에 의한 산지 하천도로의 피해유형에 따른 도로 기하구조 영향인자 분석

최민규,권기범,이광원,김홍래,이승우,Choi, Min-Gyu,Gwon, Gi-Beom,Lee, Kwang-Won,Kim, Hong-Rae,Lee, Seung-Woo 한국도로학회 2009 한국도로학회지 Vol.11 No.2

자유롭게 움직이는 탄성체의 실시간 시뮬레이션

최민규(Min Gyu Choi),홍현민(Hyun-Min Hong),고형석(Hyeong-Seok Ko) 한국컴퓨터그래픽스학회 2006 컴퓨터그래픽스학회논문지 Vol.12 No.2

김종직 강학(講學) 네트워크와 도덕적 권위의 확산

최민규 ( Choi Min Gyu ) 연세사학연구회 2019 學林 Vol.44 No.-

본고의 목표는 김종직 문인들의 결집 과정, 그리고 정치세력화, 상호 협력과 갈등을 통한 성리학 지식 확립과 확산 노력을 네트워크라는 관점에서 살펴본 글이다. 김종직의 강학 활동은 경향의 유교 지식인 간의 네트워크를 촉진하고 그것이 의도하지 않은 가운데 당으로 불릴 정도로 정치화되어 가는 과정을 보여주고 있었다. 그리고 명분 의리의식을 매개로 특정한 정치적 입장을 견지하는 붕당으로 발전시켜 나감으로써, 붕당으로 나아가는 전초 단계를 보여주었다. 한편으로 김종직 문인들은 조정에서 상호 협력하는 가운데 도학자적 지향을 강화시켜 나갔으며, 상호 간의 논란을 통해서 도학의 성격을 재규정해 나가기 시작하였다. 이 점에서 김종직 문인들은 15세기 후반 권력구조적인 차원에서는 군주 중심의 수직적 질서의 균열 속에서 공통된 학문을 통한 상호 결집된 정치집단의 원형을 형성하였고, 당시 사회·경제적 변동과 맞물려 새롭게 성장하고 있는 계층인 사족들에게 새로운 권위의 원천으로 도덕적 권위를 창안하고 있었던 것이었다. 이는 16세기 사림세력의 정치, 사회론의 원형을 이룬다는 점에서 의의가 있다고 하겠다. The goal of this paper is to look at the political power of Kim Jong-jik’s disciple and the pattern of spreading neoconfucian through mutual cooperation or conflict. Kim Jong-jik’s academic activities were promoting a network of Confucian intellectuals in the trend and showing the process of politicizing it to the point of being called the party while it was unintentionally. By developing a particular political position through the medium of justification and loyalty, the party showed a prelude to moving on to the party. On the other hand, Kim Jong-jik strengthened his neoconfucian stance while cooperating with each other in the government, and began to re-regulate the character of DaoXue through mutual controversy. In this regard, the Kim Jong-jik disciple formed the prototype of a mutually united political group through common learning in the cracks of the monarchy-centered vertical order in the latter half of the 15th century, and were creating moral authority as a source of new authority for the family, a newly growing class in line with social and economic fluctuations at the time. This is meaningful in that it forms the original form of political and social theory of the 16th century self-employed.

두 타원체 사이의 최단 근접 거리를 구하는 실용적인 방법

최민규(Min Gyu Choi) 한국게임학회 2019 한국게임학회 논문지 Vol.19 No.1

본 논문에서는 두 타원체 사이의 중심 간 방향으로의 최단 근접 거리를 구하는 실용적인 방법을 제안한다. 이는 타원체로 근사한 강체 및 변형체의 물리기반 동적 시뮬레이션에서 타원체 사이의 충돌을 처리 하는 핵심 기술이다. 본 논문에서는 외부에서 접하는 두 타원체의 중심 간 거리와 접촉점 및 접촉방향에 관한 조건식을 세우고 고정점 반복법 및 Aitken의 델타 자승 절차를 이용하여 최단 근접 거리를 구하는 방법을 개발한다. 또한 실제 오차에 따른 종료 조건을 도입함으로써 게임 등의 실시간 응용에서 최단 근접 거리를 더욱 빠르게 구할 수 있게 한다. 다양한 실험을 통해 제안된 방법의 효율성 및 실용성을 보인다. This paper presents a practical method to compute the closest approach distance of two ellipsoids in their inter-center direction. This is the key technique for collision handling in the dynamic simulation of rigid and deformable bodies approximated with ellipsoids. We formulate a set of equations with the inter-center distance and the contact point and normal for the two ellipsoids contacting each other externally. The equations are solved using fixed-point iteration and Aitken’s delta-squared process. In addition, we introduce a novel stopping criterion expressed in terms of the error in distance. We demonstrate the efficiency and practicality of our method in various experiments.

Real-Time Elastodynamic Deformation of Thin Shell Structures

Min Gyu Choi(최민규),Hyeong-Seok Ko(고형석),Seung Yong Woo(우승용) 한국컴퓨터그래픽스학회 2006 컴퓨터그래픽스학회논문지 Vol.12 No.1

Real-Time Simulation of Large Rotational Deformation and Manipulation

Min Gyu Choi(최민규),Hyeong-Seok Ko(고형석) 한국컴퓨터그래픽스학회 2004 컴퓨터그래픽스학회논문지 Vol.10 No.1

연구보문 : 자연과학; 벼 무논점파 재배시 입모 향상을 위한 물관리 방법

최민규 ( Min Kyu Choi ),구본일 ( Bon Il Ku ),강신구 ( Shin Gu Kang ),상완규 ( Wan Gyu Sang ),백남현 ( Nam Hyun Back ),김영두 ( Young Doo Kim ),박홍규 ( Hong Kyu Park ),최원영 ( Weon Young Choi ),박태선 ( Tae Seon Park ),김보경 ( B 한국국제농업개발학회 2013 韓國國際農業開發學會誌 Vol.25 No.3

Water management and weed control in rice direct seeding on puddled paddy surface is important for seedling establishment and early growth. To develop management method for enhancing seedling stands and weed control, three experiments were conducted with rice variety Hopum (midmaturing) at experimental station of National Institute of Crop Science, in Iksan in 2010-2011. In experiment 1, germinated rice seeds were sowed on 1, 2, 3, and 4 days after puddling to find the optimum drying days of paddy surface. The average numbers of seedling stands in 2 and 3 days drying were 117 and 114 per m2, respectively, and those were higher than in the 1 and 4 days. Plant height and root length were increased as drying up to 3 days, but decreased in the 4th day. In experiment 2, non-irrigation and intermittent irrigation started 2, 4, and 6 days after seeding were evaluated. The average numbers of seedlings in intermittent irrigation from 2 and 4 days after seeding were 117 and 113 per m2, respectively. The seedlings in irrigation after 6 days was 92 per m2, and 84 per m2 in non-irrigation. Shoot lengths were highest in the irrigation treatments of 2 days and 4 days after seeding. In experiment 3, herbicide was treated on 10, 12, 14, and 16 days after seeding. Rice seedling and root length was increased in the later herbicide treatments. Weeds were not occurred until the 12 days, but observed in the later two treatments. According to these findings, drying paddy for 3 days after puddling, intermittent irrigating after 2 days from seeding, and herbicide treatment on 12 days after seeding is recommended for direct seeding on puddled paddy surface.

눈물흘림 환자에서 눈물길미세내시경의 사용 여부에 따른 실리콘관삽입술의 성공률 비교

최민규(Min Gyu Choi),이정규(Jeong Kyu Lee) 대한안과학회 2018 대한안과학회지 Vol.59 No.11

목적: 눈물길미세내시경을 이용한 실리콘관삽입술과 기존의 코내시경만으로 시행한 방법 간의 성공률을 비교하고자 하였다. 대상과 방법: 2014년 1월부터 2017년 6월까지 본원에서 실리콘관삽입술을 시행한 환자들을 대상으로 하였다. 술 전 눈물소관 관류검사와 눈물주머니조영술로 진단하였다. 술 후 3개월 때 실리콘관을 제거하였고 4, 12개월 때 성공률을 내시경 사용에 따라 두 군으로 나눠 분석하였다. 결과: 총 55명, 80안으로 술 전 진단에서 사용군은 부분폐쇄 26안, 완전폐쇄 14안, 미사용군은 부분폐쇄 35안, 완전폐쇄 5안이었다(p=0.018). 술 후 4, 12개월 때 성공률은 사용군에서는 87.5%, 80.0%, 미사용군에서는 72.0%, 62.1%였다(p=0.546, p=0.565). 부분폐쇄에서 사용군과 미사용군의 성공률은 4개월 때 92.3%, 82.9%, 12개월 때 71.4%, 62.9% (p=0.448, p=1.000), 완전폐쇄에서 성공률은 4개월 때 78.6%, 60.0%, 12개월 때 72.7%, 33.3%였다(p=0.570, p=0.505). 눈물길미세내시경의 사용과 폐쇄의 위치 및 정도의 차이가 술 후 4, 12개월 때 성공률에 유의한 영향을 미침을 확인하였다(p=0.001, p=0.022). 결론: 눈물길미세내시경을 이용한 실리콘관삽입술은 기존의 것에 비하여 성공률이 유의하게 높지는 않았으나, 코눈물길의 구조를 실시간으로 확인하여 적절한 진단 및 치료가 동시에 가능하다. 완전폐쇄로 진단되었던 환자들에게도 좋은 성공률을 보여 그 적용 범위를 확대시켜 비침습적인 치료를 시행할 수 있을 것이다. Purpose: To compare the success rates between silicone tube intubation using a lacrimal endoscope and using a conventional nasal endoscope alone in adult patients suffering from epiphora. Methods: We conducted a retrospective chart review of 80 eyes of 55 patients who underwent silicone tube intubation from January 2014 to June 2017. Patients were preoperatively diagnosed with syringing and dacryocystography. The silicone tube was removed 3 months after surgery and success rates were evaluated at 4 and 12 months. Success rates were analyzed by dividing the patients into two groups, according to lacrimal endoscope use. Results: A lacrimal endoscope was used in 40 eyes. In the group using a lacrimal endoscope, preoperative diagnoses were partial obstruction in 26 eyes and complete obstruction in 14 eyes. In the group without lacrimal endoscope use, preoperative diagnoses were partial obstruction in 35 eyes and complete obstruction in 5 eyes (p = 0.018). The success rates at 4 and 12 months after surgery in the two groups (with and without lacrimal endoscope use) were 87.5% and 80.0% and 72.0% and 62.1% (p = 0.546 and p = 0.565), respectively. The success rates of patients with partial obstruction in the two groups were 92.3% and 82.9% at 4 months and 71.4% and 69.2% at 12 months (p = 0.448 and p = 1.000), respectively. The success rates of patients with complete obstruction in the two groups were 78.6% and 60.0% at 4 months and 72.7% and 33.3% at 12 months (p = 0.570 and p = 0.505), respectively. Site differences, the degree of obstruction, and lacrimal endoscope use had a significant impact on the success rate at 4 and 12 months (p = 0.001 and p = 0.022, respectively). Conclusions: Although silicone tube intubation using a lacrimal endoscope cannot guarantee a significant success rate, it is possible to observe the anatomical structure of the nasolacrimal pathway in real time, such that the appropriate diagnosis and treatment can be performed simultaneously. Because patients diagnosed as having a complete obstruction had a good success rate, we can extend indication of silicone tube intubation as a less invasive approach.

두 타원체 사이의 최단 접근 거리를 구하는 안정적이며 효율적인 방법

최민규(Min Gyu Choi) 한국게임학회 2019 한국게임학회 논문지 Vol.19 No.6

본 논문에서는 두 타원체 사이의 중심 간 방향으로의 최단 접근 거리를 구하는 방법을 다룬다. 이는 타원체 사이의 충돌 검사 및 반응에 있어서 핵심 기술이다. 외부에서 서로 접하는 두 타원체의 중심 사이의 거리와 접촉점, 접촉방향에 관한 조건식을 세우고, 해를 포함하는 구간을 유지하는 이분법과 도함수를 이용하는 Newton 방법의 혼합을 통해 최단 접근 거리를 항상 안정적이며 효율적으로 구할 수 있게 한다. 또한 다양한 실험을 통해 제안된 방법의 안정성 및 효율성을 보인다. This paper addresses a method to compute the closest approach distance between two ellipsoids in their inter-center direction. This is the key technique for collision detection and response between ellipsoids. We formulate a set of conditions with the inter-center distance, the contact point and the contact normal vector of the two externally-contacting ellipsoids. The equations are solved robustly and efficiently using a hybrid of Newton’s method and the bisection method with root bracketing. We demonstrate the robustness and efficiency of the proposed method in various experiments.