• 한국해양공학회지
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• 제23권5호
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• pp.61-70
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• 2009

An AUV (Autonomous Underwater Vehicle) is an unmanned underwater vessel to investigate sea environments and deep sea resource. To be completely autonomous, AUV must have the ability to home and dock to the launcher. In this paper, we consider a class of homing trajectory planning problem for an AUV with kinematic and tactical constraints in horizontal plane. Since the AUV under consideration has underactuated characteristics, trajectory for this kind of AUV must be designed considering the underactuated characteristics. Otherwise, the AUV cannot follow the trajectory. Proposed homing trajectory panning method that called VGM (Virtual Goal Method) based on visibility graph takes the underactated characteristics into consideration. And it guarantees shortest collision free trajectory. For tracking control, we propose a PD controller by simple guidance law. Finally, we validate the trajectory planning algorithm and tracking controller by numerical simulation and ocean engineering basin experiment in KORDI.

• 한국주거학회논문집
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• 제21권4호
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• pp.89-97
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• 2010

Digital convergence era has been already started and is rapidly developed. Recently, convergency technology became an essential issue in all industries, and is expected to accelerate. This means that we can experience growth and change of architecture using new technology and approaching method. The AR (Augmented Reality) technology, among these convergence technology, is a kind of virtual reality technology that user can see a scene of real world which is overlapped by virtual world with additional information. It has been used in manufacturing and management in the whole industry fields including medical, mechanical, military field and so on because it can provide higher sense of reality. Thus, in this paper, we suggest the utilization of AR technology for organically connecting the roads, facilities, green area, landscape and others in the layout planning of housing complex. Users can see real world with virtual object by overlap computer graphic on the real world. This method provides users with various information about territoriality and openness. As the result of this study it is expected that this technology will help the layout planning of housing complex to become more reasonable in the aspect of design, time and cost.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1636-1639
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• 2005

The process equipment and remote handling for the deep geological disposal of high-level radioactive waste(HLW) should be checked prior to the operation in view of reliability and operability. In this study, the concept of virtual environment workcell is implemented to analyze and define the feasible disposal process instead of real mock-up, which is very expensive and time consuming. To do this, the parts of process equipment for the disposal and maintenance will be modeled in 3-D graphics, assembled, and kinematics will be assigned. Also, the virtual workcell for the encapsulation and disposal process of spent fuel will be implemented in the graphical environment, which is the same as the real environment. This virtual workcell will have the several functions for verification such as analyses for the equipment's work space, the collision detection, the path planning and graphic simulation of the processes etc. This graphic virtual workcell of the HLW disposal process can be effectively used in designing of the processes for the hot cell equipment and enhance the reliability of the spent fuel management.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1819-1826
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• 2009

To enhance the automatic performance of existing predicting and planning algorithms that require a predefined probability of the states' transition, this paper proposes a multiple sequence generation system. When interacting with unknown environments, a virtual agent needs to decide which action or action order can result in a good state and determine the transition probability based on the current state and the action taken. We describe a sequential behavior generation method motivated from the change in the agent's state in order to help the virtual agent learn how to adapt to unknown environments. In a sequence learning process, the sensed states are grouped by a set of proposed motivation filters in order to reduce the learning computation of the large state space. In order to accomplish a goal with a high payoff, the learning agent makes a decision based on the observation of states' transitions. The proposed multiple sequence behaviors generation system increases the complexity and heightens the automatic planning of the virtual agent for interacting with the dynamic unknown environment. This model was tested in a virtual library to elucidate the process of the system.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.35.1-35.7
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• 2019

Background: The purpose of this study was to measure the time of the conventional surgical planning (CSP) and virtual surgical planning (VSP) in orthognathic surgery and to compare them in terms of cost. Material and method: This is a retrospective study of the patients who underwent orthognathic surgery at the Pusan National University Dental Hospital from December 2017 to August 2018. All the patients were analyzed through both CSP and VSP, and all the surgical stents were fabricated through manual and three-dimensional (3D) printing. The predictor variables were the planning method (CSP vs. VSP) and the surgery type (group I: Le Fort I osteotomy + bilateral sagittal split osteotomy [LFI+BSSO] or group II: only bilateral sagittal split osteotomy [BSSO]), and the outcomes were the time and cost. The results were analyzed using the paired t test. Results: Thirty patients (12 females, 18 males) met the inclusion criteria, and 17 patients were excluded from the study due to missing or incomplete data. There were 20 group I patients (LFI+BSSO regardless of genioplasty) and 10 group II patients (BSSO regardless of genioplasty). The average time of CSP for group I was 385 ± 7.8 min, and that for group II was 195 ± 8.33 min. The time reduction rate of VSP compared with CSP was 62.8% in group I and 41.5% in group II. On the other hand, there was no statistically significant cost reduction. Conclusions: The time investment in VSP in this study was significantly smaller than that in CSP, and the difference was greater in group I than in group II.

• 한국게임학회 논문지
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• 제9권3호
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• pp.139-150
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• 2009

본 논문에서는 가상 에이전트의 행동 계획을 위한 인터렉티브 지식베이스 구축과 인터렉티브 지식베이스를 바탕으로 하는 계획시스템에 관한 방법을 제안한다. 고정적인 지식베이스는 고정적인 계획 수립만 가능하기 때문에 환경의 변화에 잘 대처하지 못한다. 그래서 이 논문에서는 다양한 환경에서 적용이 가능한 인터렉티브한 지식베이스의 구축과 인터렉티브 지식베이스를 활용할 수 있는 인공지능 계획시스템을 제안한다. 본 연구에서 제안한 인터렉티브 지식베이스는 동기, 행동, 사물, 실행의 4가지로 이루어지며 지식베이스의 입력과 지식베이스들 사이의 연관관계는 개발된 자동화 툴을 사용하여 설정한다. 이 툴을 사용하여 사용자는 쉽게 지식베이스에 구성요소들을 추가 또는 수정할 수 있다. 이 지식베이스를 바탕으로 캐릭터는 행동가능한 모든 항목들을 계획을 세우게 되며 이 중 한 가지를 선택하여 행동을 하게 된다. 후에 캐릭터의 환경이 변하게 되더라도 지식베이스의 업데이트를 통해 새로운 행동을 적용시킬 수가 있기 때문에 가상현실 콘텐츠제작자의 입장에서는 상당히 유용하다. 본 논문에서는 확장성이 있는 인터렉티브 지식베이스 구성요소와 구성요소들 사이의 관계설정 그리고 이를 쉽게 입력할 수 있는 툴과 인터렉티브 지식베이스에 적합한 계획시스템의 알고리즘을 제안하여 가상도서관이라는 가상환경에서 실험을 통해 결과를 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.885-888
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• 1995

Virtual Manufacturing System(VMS) is a computer model that represents the precise and whole structure of manufacturing system and simulates their physical and logical behavior in operation. In this paper, a real time simulation for the virtual factory is proposed to integrate a process planning with scheduling under distributed environments. In order to communicate the information under distributed environment, weuse a sever/client concept and socket program. the VMS is implemented on the internet environment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.55.6-55
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• 2002

Huafei Liao is a graduate student of the Automation department in Tsinghua University, China. His research involves computer-aided process planning, 3D CAD/CAM, virtual reality, and feature recognition.

• 대한인간공학회지
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• 제36권1호
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• pp.37-52
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• 2017

Objective: The present study developed a user-centered 3D virtual liver surgery planning (VLSP) system called Dr. Liver to provide preoperative information for safe and rational surgery. Background: Preoperative 3D VLSP is needed for patients' safety in liver surgery. Existing systems either do not provide functions specialized for liver surgery planning or do not provide functions for cross-check of the accuracy of analysis results. Method: Use scenarios of Dr. Liver were developed through literature review, benchmarking, and interviews with surgeons. User interfaces of Dr. Liver with various user-friendly features (e.g., context-sensitive hotkey menu and 3D view navigation box) was designed. Novel image processing algorithms (e.g., hybrid semi-automatic algorithm for liver extraction and customized region growing algorithm for vessel extraction) were developed for accurate and efficient liver surgery planning. Usability problems of a preliminary version of Dr. Liver were identified by surgeons and system developers and then design changes were made to resolve the identified usability problems. Results: A usability testing showed that the revised version of Dr. Liver achieved a high level of satisfaction ($6.1{\pm}0.8$ out of 7) and an acceptable time efficiency ($26.7{\pm}0.9 min$) in liver surgery planning. Conclusion: Involvement of usability testing in system development process from the beginning is useful to identify potential usability problems to improve for shortening system development period and cost. Application: The development and evaluation process of Dr. Liver in this study can be referred in designing a user-centered system.

• 한국정밀공학회지
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• 제18권1호
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• pp.63-73
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• 2001

This paper presents a process and operation planning system with an NC code post-processor for effective machining of press dies for production of cars. Based on the machining features, major parts of press dies are categorized into 15 groups and a standard process plan is defined for each group. The standard process plan consists of a series of processes where a process is defined as a group of operations that can be done with one setup. Details such as cutting tools, cutting conditions, and tool paths are decided at the operation planning stage. At the final stage of process and operation planning, the NC code post-processor we developed adjusts feedrates along the tool path to reduce machining time. The adjustment rule is selected based on the metal removal rate estimated by virtually machining with virtual cutting tool.