• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.163-167
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• 2009

본 논문에서는 크게 2단계에 걸쳐 다양한 형태의 얼굴을 가진 2차원 애니메이션 상의 캐릭터 얼굴구성요소를 추출하고 표정을 분석한다. 첫 번째 단계에서는, 기존의 얼굴인식 및 표정인식 분야에서 이용되었던 동적메쉬모델을 간소화하여 캐릭터 얼굴에 적용하기 위한 최적의 표준 메쉬모델을 제작하고, 이 모델을 사용하여 얼굴구성요소의 위치 및 형태정보를 추출한다. 두 번째 단계에서는, 앞 단계에서 추출된 3가지 얼굴구성요소(눈썹, 눈, 입)를 사용하여 FACS(Facial Action Coding System)에 정의된 AU(Action Units) 44개 중 12개의 AU를 사용하여 캐릭터의 5까지 기본적인 얼굴 표정에 대해 분석 및 정의한다. 본 논문에서 정의한 AU로 기본적인 5가지 얼굴표정에 대해 표정분석 정확도를 측정하였고, 서로 다른 캐릭터에 실험함으로써 제안된 AU정의의 타당성을 제시한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.339-340
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• 2022

본 논문에서는 사용자의 다양한 물리적 속성 중 부드러운 헤비사이드 계단 함수와 다양한 물리적 속성(속도, 시점 등)을 활용하여 가중치 맵을 계산하고 이로부터 논플레이어 캐릭터(Non-player character, NPC)의 경로를 효율적으로 제어할 수 있는 NavMesh 제어 기법을 제시한다. 게임과 같은 가상환경에서 NPC는 일반적으로 네비게이션 메쉬(Navigation mesh, NavMesh)를 이용하여 이동한다. 하지만, NavMesh는 정적인 형태이기 때문에 사용자에 의해 디자인되어야 하고, 이러한 문제를 완화하고자 자동으로 NavMesh를 업데이트하는 기술이 연구되고 있지만, 메쉬 복원을 자동화할 뿐 실제 NPC 행동 제어라고 하기에는 힘든 접근법이다. 본 논문에서는 동적 네비게이션 프레임워크를 유지한 채, 사용자의 시점과 물리적 특성을 통해 NPC를 효율적이고 정확하게 경로 제어할 수 있는 방법을 제안하고, NavMesh의 형태에만 의존하던 NPC의 움직임을 완화하여 좀 더 사실적인 경로 제어를 보여준다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.156-157
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• 2023

사물인터넷은 무선 통신 기술의 발달로 스마트 시티, 스마트 홈, 스마트 농장, 스마트 건물, 스마트 공장과 같은 다양한 분야에서 주목을 받고 있다. 특히 무선 통신 기술 중 하나인 블루투스 메쉬는 비동기 동적 스캐닝을 이용하여 저전력 통신을 제공하기 때문에 사물인터넷 분야에서 주목을 받고 있다. 본 논문은 네트워크의 신뢰성을 유지하면서 적은 계산 복잡도로 에너지 효율을 높이는 방법을 제안한다. 이를 통해 대부분의 저전력 무선네트워크 환경에서 효과적인 에너지 최적화를 실현한다.

• Convergence Security Journal
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• v.11 no.1
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• pp.11-18
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• 2011

Wireless mesh network technology with transmission speeds similar to wired and wireless technology means to build, compared with wired networks, building a more efficient network to provide convenience and flexibility. The wireless mesh network router nodes in the energy impact of the mobility is less constrained and has fewer features entail. However, the characteristics of various kinds due to network configuration settings and the choice of multiple paths that can occur when the system overhead and there are many details that must be considered. Therefore, according to the characteristics of these network routing technology that is reflected in the design and optimization of the network is worth noting. In this paper, a multi-path setting can be raised in order to respond effectively to the problem of the router node data loss and bandwidth according to traffic conditions and links to elements of the hop count evaluation by using a genetic algorithm as a workaround for dynamic routing the routing metric for wireless mesh network scheme is proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.207-216
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• 2003

In this paper, the finite element method for the elastodynamic axisymmetric fracture analysis is presented in matrix form through the application of the Galerkin method to the time integral equations of motion with no inertia forces. Isoparametric quadratic quadrilateral element and triangular crack tip singular elements with one-quarter node are used in the mesh division of the finite element model. To show the validity and accuracy of the proposed method, the infinite elastic medium with the penny shaped crack is solved first and compared with the analytical solution and the numerical results by the finite difference method and the boundary element method existing in the published literatures, and then the dynamic stress intensity factors of solid and hollow cylinders of finite dimensions haying penny-shaped cracks and internal and external circumferential tracks are computed in detail.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.535-537
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• 2001

3D MMORPG(Massive Multi-play Outline Role Playing Game) 게임은 넓은 3차원원지형을 실시간으로 표현되어야 하며, 많은 어려움이 따른다. 본 논문에서는 이러한 지형 처리를 위하여 메쉬나 버텍스, 혹은 폴리곤으로 사실적인 지형처리와 렌드링 속도 향상을 위하여 3차원 폴리곤을 동적으로 생성시키는 방법을 이용하려고 한다. 넓은 지형을 처리하기 위해서는 전체를 한번에 표현하기보다는 페이지 단위로 처리하기 위하여 격자화된 타일로 이루어진 맵으로 처리할 수 있다. Height field 처리 기법은 일정한 영역을 페이지 단위로 구분하고 처리할 수 있다. 옥트리를 이용하여 공간을 입체적인 컬링 방법으로 분할하고, 이를 세부 수준으로 나누어 처리하기 위해 CLOD(Continuous Level of Detail) 개념을 적용할 수 있다. 거리의 변화에 따라 지명을 표현하는 vertex들을 병합 또는 삭제함으로써 그 표현의 정도를 동적으로 달리 할 수 있는 CLOD를 이용하여 카메라의 위치와 방향에 따라 적절한 폴리곤을 생성해 낼 수 있다. 본 논문은 3 차원의 넓은 외부 지형을 실시간으로 처리할 경우 발생되는 그래픽 문제를 해결하기 위해 사용되는 방법 중에서 대표적인 방법을 통하여 효율적인 처리 기법을 제시하려 한다.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.36-41
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• 2011

Analysis of two-dimensional flow in an involute gear pump has been done by using FLUENT. Analysis extended to the turbulent flow includes the mass flow rate with functions of pressure difference between inlet and outlet, rotational velocities of involute gear, and clearances between tip of gear and housing. In general mass flow rate decreases with decreasing rotational velocity, and with increasing clearance and pressure difference. The flow rate efficiency of gear pump, which is defined with the theoretical flow rate, has been presented in terms of the above parameters.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.89-96
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• 2023

In this paper, we propose a GPU-based method for real-time processing of dynamic re-meshing required for tearing cloth. Thin shell materials are used in various fields such as physics-based simulation/animation, games, and virtual reality. Tearing the fabric requires dynamically updating the geometry and connectivity, making the process complex and computationally intensive. This process needs to be fast, especially when dealing with interactive content. Most methods perform re-meshing through low-resolution simulations to maintain real-time, or rely on an already segmented pattern, which is not considered dynamic re-meshing, and the quality of the torn pattern is low. In this paper, we propose a new GPU-optimized dynamic re-meshing algorithm that enables real-time processing of high-resolution fabric tears. The method proposed in this paper can be used for virtual surgical simulation and physics-based modeling in games and virtual environments that require real-time, as it allows dynamic re-meshing rather than pre-split meshes.

• Journal of Korea Water Resources Association
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• v.44 no.7
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• pp.511-522
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• 2011

Two-dimensional shallow water model based on the cut cell and the adaptive mesh refinement techniques is presented in this paper. These two mesh generation methods are combined to facilitate modeling of complex geometries. By using dynamically adaptive mesh, the model can achieve high resolution efficiently at the interface where flow changes rapidly. The HLLC Reimann solver and the MUSCL method are employed to calculate advection fluxes with numerical stability and precision. The model was applied to simulate the extreme urban flooding experiments performed by the IMPACT (Investigation of Extreme Flood Processes and Uncertainty) project. Simulation results were in good agreement with observed data, and transient flows as well as the impact of building structures on flood waves were calculated with accuracy. The cut cell method eased the model sensitivity to refinement. It can be concluded that the model is applicable to the urban flood simulation in case the effects of sewer and stormwater drainage system on flooding are relatively small like the dam brake.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1050-1057
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• 2008

Wireless Mesh Networks (WMNs) have recently become a hot issue to support high link capacity in wireless access networks. The IEEE 802. I 1 standard which is mainly used for the network interface technology in WMNs supports up to 3 or 12 multiple channels according to the IEEE 802.11 specification. However, two important problems must be addressed when we design a channel assigmnent algorithm: channel dependency problem and channel scanning delay. The former occurs when the dynamic channel switching of an interface leads to the channel switching of other interfaces to maintain node connectivity. The latter happens per channel switching of the interface, and affects the network performance. Therefore, in this paper, we propose the Distance-Based Channel Assigmnent (DB-CA) scheme for multi-channel WMNs to solve such problems. In DB-CA, nodes just perform channel switching without channel scanning to communicate with neighboring nodes that operate on different channels. Furthermore, DB-CA minimizes the interference of channels being used by nodes near the gateway in WMNs. Our simulation results show that DB-CA achieves improved performance in WMNs.