• Journal of the Korea Society of Computer and Information
• /
• v.24 no.10
• /
• pp.79-89
• /
• 2019

While most research focuses on the k-nearest neighbors (kNN) queries in the database community, an important type of proximity queries called k-farthest neighbors (kFN) queries has not received much attention. This paper addresses the problem of finding the k-farthest neighbors in road networks. Given a positive integer k, a query object q, and a set of data points P, a kFN query returns k data objects farthest from the query object q. Little attention has been paid to processing kFN queries in road networks. The challenge of processing kFN queries in road networks is reducing the number of network distance computations, which is the most prominent difference between a road network and a Euclidean space. In this study, we propose an efficient algorithm called FANS for k-FArthest Neighbor Search in road networks. We present a shared computation strategy to avoid redundant computation of the distances between a query object and data objects. We also present effective pruning techniques based on the maximum distance from a query object to data segments. Finally, we demonstrate the efficiency and scalability of our proposed solution with extensive experiments using real-world roadmaps.

• Proceedings of the Korean Information Science Society Conference
• /
• 2011.06a
• /
• pp.57-60
• /
• 2011

도로 환경에서 이동하는 객체에 효율적인 위치기반 서비스를 제공하기 위해 다양한 브로드캐스트 기법들이 연구 되어 왔다. 하지만 실시간으로 변하는 도로 환경을 고려한 효율적인 브로드캐스트 기법이 요구되고 있다. 본 논문에서는 도로 특성을 고려한 양방향 선형 브로드캐스트 색인 구조를 제안하고, 빈번하게 변화하는 도로 환경을 고려하여 센서 네트워크를 통해 수집되는 도로 정보를 기반으로 최적의 QoS(Quality of Service)를 유지시키는 브로드캐스트 전략 갱신 기법을 제안한다. 또한 질의 처리 속도 향상을 위해 서비스 지역을 센서 클러스터 기반의 지역 세그먼트로 분할하여 불필요한 데이터의 브로드캐스트를 제거하는 분산 브로드캐스트 서비스 구조를 제안한다. 제안하는 기법의 우수성을 증명하기 위해 기존에 제안된 브로드캐스트 기법과 성능을 비교 평가한다.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.995-996
• /
• 2008

This paper proposes a algorithm that generate the intermediate scene from the stereo image. This system based on mesh representation method, and segmented objects which ar calculated from triangles the pro proposed algorithm is composed of two steps. One is triangle grouping using gestalt theory, and the other is disparity estimation using average disparity of segmented object. We make an experiment on the proposed algorithm with some stereo images and obtain good quality disparity map for intermediate scenes.

• Journal of the Korea Computer Graphics Society
• /
• v.11 no.1
• /
• pp.50-54
• /
• 2005

본 논문은 관상동맥의 구조와 그 움직임을 사실적으로 표현하기 위한 매개변수적 모델링기법을 제안한다. 매개변수적 기법으로 생성된 모델은 메쉬 정점의 인덱스만으로 모델간 매칭을 위한 대응점을 찾을 수 있으므로, 시간대별로 달라지는 정점의 위치를 쉽게 추적함으로써 모델의 움직임을 표현할 수 있다. 그러나 이러한 기법으로 생성된 모델은 분리, 접합 등의 변형 조작이 어렵고, 트리형태 객체에 적용하기 힘든 단점이 있다. 본 논문에서는 이를 극복하기 위해 분할된 혈관영역의 골격데이타에서 찾아낸 분기점을 중심으로 Generalized Cylinder를 이용하여 실린더 형태의 각 혈관세그먼트를 모델링 한 후, 분기영역을 3 개의 하프파이프(half pipe)와 2 개의 삼각형 패치로 연결하여 모델링하였다. 완성된 모델은 다시점 관상동맥데이터에 적용하였고, 각 시점에서 구해진 정점의 위치를 선형보간함으로써 부드러운 혈관의 움직임을 나타내었다.

• The KIPS Transactions:PartB
• /
• v.11B no.6
• /
• pp.691-700
• /
• 2004

This paper proposes a user's mobility based cooperative proxy caching policy for effective resource management of continuous media objects in mobile environments. This policy is different from the existing proxy caching policies in terms of how to exploit users' mobility. In other words, existing caching policies work based on the information about objects by referring to user's requests within a specified domain whereas the proposed caching policy runs by utilizing a number of user's requests across several domains. So, the proposed policy is applicable to random requests in mobile environments Moreover, we also propose a replacement policy based on weights and playback time. To check the efficiency of the proposed caching policy, the proposed replacement policy is run with different size of caching unit object or segment. The result of performance analyze tells what a ratio of user's mobility is are major factors for the efficient operation of the cooperative caching.

• Journal of Internet Computing and Services
• /
• v.18 no.1
• /
• pp.43-50
• /
• 2017

In this paper, we are proposing improved vanishing points detection and segments labeling methods for inside wall frame detection from indoor image of a piece of having a colour RGB. A lot of research related to recognizing the frame of artificial structures from the image is being performed due to increase in demand for AR technology. But detect the inside wall frame in indoor images have many objects that caused the occlusion is still a difficult issue. Inner wall frame detection methods are usually segment labeling methods and detect vanishing point methods are used together. In order to improve the vanishing point detection method we proposed using inner wall orthogonality which forms the cube. Also we proposed labeling method using tree based learning and superpixel based segmentation method for labelingthe segments in indoor images. Finally, in experiments have shown improved results about inside wall frame detection according to our methods.

• Journal of Korea Spatial Information System Society
• /
• v.10 no.3
• /
• pp.1-18
• /
• 2008

Because we can usually get many information through analyzing trajectories of moving objects on spatial networks, efficient trajectory index structures are required to achieve good retrieval performance on their trajectories. However, there has been little research on trajectory index structures for spatial networks such as FNR-tree and MON-tree. Also, because FNR-tree and MON-tree store the segment unit of moving objects, they can't support the trajectory of whole moving objects. In this paper, we propose an efficient trajectory index structures based on signatures on a spatial network, named SigMO-Tree. For this, we divide moving object data into spatial and temporal attributes, and design an index structure which supports not only range query but trajectory query by preserving the whole trajectory of moving objects. In addition, we divide user queries into trajectory query based on spatio-temporal area and similar-tralectory query, and propose query processing algorithms to support them. The algorithm uses a signature file in order to retrieve candidate trajectories efficiently Finally, we show from our performance analysis that our trajectory index structure outperforms the existing index structures like FNR-Tree and MON-Tree.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.3
• /
• pp.265-271
• /
• 2020

Automotive radar that is one of the most important equipment in high-tech vehicles, is commonly used to detect the speed and range of objects such as cars. In this paper, in addition to objects detection, a method of retrieving precipitation information using the automotive radar data is proposed. The proposed method is based on the fact that the degree of attenuation of the returned radar signal differs depending on the precipitation intensity and the assumption that the distribution of precipitation is constant in short spatial and temporal observation. The purpose of this paper is to assesses the possibility of retrieving precipitation information using a vehicle radar. To verify the feasibility of the proposed method during actual driving, a method of estimating precipitation information for each time segment of various precipitation events was applied. From the results of driving field experiments, it was found that the proposed method is suitable for estimating precipitation information in various rainfall types.

• 한국HCI학회:학술대회논문집
• /
• 2006.02a
• /
• pp.480-485
• /
• 2006

본 논문에서는 사용자가 NURBS 곡면을 다양한 형태로 변형을 손쉽게 할 수 있는 수정된 유한요소법을 이용한 곡면 변형의 방법을 제시한다. 수정된 유한요소법은 NURBS 기저함수를 전통적 유한요소법의 형상함수를 대신하여 유한요소해석을 한다. 모델링된 객체는 NURBS 곡면으로 이루어져 있고, 각각의 세그먼트별로 나누어진 기저함수와 제어점으로 구성되어있기 때문에 번거롭게 요소와 형상함수를 따로 구하지 않아도 되며, 자체 보간 방식이므로 기존의 유한요소법에 비해 적은 요소와 절점으로 곡면을 해석 할 수 있다. NURBS 곡면 변형은 각각의 제어점에 의해 구역이 나눠지고 각 구역은 변형될 지점과 가장 가까운 제어점으로 구성된 구역의 제어점들을 변형시킬 지점과 각 제어점의 거리 비례에 따라서 제어점 들의 속도가 지정되어 변형을 완성한다. 제시된 변형 방법은 다른 변형들과 같이 초기 입력에 의해 변형이 한 순간에 진행되는 것이 아니라 점진적 변형이 일어나며, NURBS 의 특징인 전체 제어점 변형으로 인해 의도하지 않은 변형이 일어나는 것을 변형 중간에 각각의 제어점의 속도를 제어함으로써 사용자의 의도한 변형으로 빠른 시간에 완성할 수 있게 된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.9
• /
• pp.94-102
• /
• 2003

This paper describes the development and implementation for the SYMBOLGEN(SYMBOL GENerator) software. The SYMBOL-GEN software is for improving graphic processing speed and decreasing data communication load in ASC by genera ting and downloading off-line symbol file for HUD and MFD , which are the main display equipments in military aircraft. The SYMBOL-GEN is developed on PC using C++ language and MS Visual Studio 6.0 development tool. It is also designed to be modified and extended easily by introducing object-oriented software development technique.