• 한국CDE학회논문집
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• 제16권4호
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• pp.277-284
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• 2011

In tangible augmented reality (AR) environments for virtual prototyping, the user interacts with virtual products by manipulating tangible objects with his or her hands, but the user often encounter awkward situations in which his or her hands are occluded by augmented virtual objects, which reduces both immersion and ease of interaction. In this paper, we present how to resolve such hand region occlusion in order to enhance natural interaction and immersive visualization. In the AR environment considered, we use two types (product-type and pointer-type) of tangible objects for tangible user interaction with a virtual product of interest. Holding the tangible objects with his or her hands, the user can create input events by touching specified regions of the product-type tangible object with the pointer-type tangible object. We developed a method for resolving hand region occlusion frequently arising during such user interaction, It first detect hand region in a real image and refines the rendered image of the virtual object by subtracting the hand region from the rendered image, Then, it superimposes the refined image onto the real image to obtain an image in which the occlusion is resolved. Incorporated into tangible AR interaction for virtual prototyping of handheld products such as cellular phones and MP3 players, the method has been found by a preliminary user study that it is not only useful to improve natural interaction and immersive visualization of virtual products, but also helpful for making the users experience the products' shapes and functions better.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2002년도 춘계학술발표논문집(하)
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• pp.901-906
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• 2002

본 논문은 신속조형(RP: rapid prototyping) 시스템에서 사용되며 3D 기하학적 형상 모델을 가지고 있는 STL(standard transform language)에 워터마크를 삽입하는 방법에 관한 연구이다. 제안된 알고리즘은 3D 형상 데이터의 왜곡이 전혀 없이 패싯(facet, mesh)의 버텍스(vertex) 영역에 워터마크를 삽입한다. 기존의 알고리즘으로 STL에 워터마크를 삽입할 경우, 패싯의 저장순서를 변경하는 단순한 공격으로도 워터마크가 제거된다. 제안된 알고리즘은 패싯의 저장 순서 변경과 같은 공격에 대한 강인성을 가질 뿐만 아니라, 비가시성(invisibility)도 충족한다. 제안된 알고리즘으로 STL 3D 형상에 워터마크를 삽입하고 추출하는, 실험 결과들은 3D 원형상을 전혀 왜곡하지 않고 워터마크의 삽입과 추출이 가능함을 보여준다.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2235-2245
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• 2000

The necessity of using rapid prototyping(RP) for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy, materials, aid cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed. For the new hybrid RP process to maintain the same degree of process automation as in currently available processes like SLA or FDNI, a sophisticated process planning system is developed. In the process planner, CAD models(STEP AP203) are partitioned into 3D manufacturable volumes called 'Ueposition feature segment"(DFS) after machining features called "machining feature segmenf'(MFS) are extracted from the initial CAD model. Once MFS and DFS are identified, the process planner arranges them into a chain of processes and automatically generates machining information for each DFS and MFS. The goal of this paper is to present a framework for a process planning system for hybrid RP processes and to outline the geometric algorithms involved in developing such an environment.

• 한국정밀공학회지
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• 제17권7호
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• pp.124-131
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• 2000

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.529-530
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• 2006

Manufacturing industry is changing rapidly. Prototyping with rapid manufacturing is a part of every business in many companies and prototypes are used efficiently as a part of the production development process. Sheet metal forming has traditionally been a technology area where prototyping has been extremely expensive and efficient options for low volume have been limited. This paper describes the process for incremental sheet forming technologies to make the prototype for a brake dust shield of vehicles, which includes the remodeling method to make a base mold and tool path for sheet metal forming and 5-axes laser cutting machine to trim the prototype product.

• 한국정밀공학회지
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• 제21권6호
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• pp.188-196
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• 2004

The objective of this paper is to propose a new technology of the orthopaedic surgery using the combination of reverse engineering (RE) based on CT data and rapid prototyping (RP). The proposed technology utilizes symmetrical characteristics of the human body and capability of the combination of RE and RP, which rapidly manufactures three-dimensional parts from CT data. The original .stl data of injured extents are generated from the mirror transformation of .stl file fur uninjured extents. The physical shape before injuring is manufactured from RP using the original .stl data. Subsequently, pre-operative planning, such as a selection of proper implants, preforming of the implant, a decision of fixation locations and an insert position for the implant, an estimation of the invasive size, and pre-education of operators are performed using the physical shape. In order to examine the applicability and the efficiency of the proposed surgical technology, various case studies, such as a distal tibia commented fracture, a proximal tibia plateau fracture and an iliac wing fracture of pelvis, are carried out. From the results of case studies, it has been shown that the proposed technology is an effective surgical tool of the orthopaedic surgery reducing the operational time, the operational cost, the radiation exposure of the patient and operators, and morbidity. In addition, the proposed technology could improve the accuracy of operation and the speed of rehabilitation.

• 정보교육학회논문지
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• 제14권1호
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• pp.69-77
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• 2010

교육 패러다임의 전환과 함께 학교교육에서 응용 프로그램 개발교육의 중요성이 부각되고 있으나 여러 현실적인 문제로 인하여 학교 현장에서의 응용 프로그램 개발교육이 제대로 이루어지지 못하고 있는 실정이다. 본 연구에서는 초등학생들이 어려워하는 프로그래밍 코딩 단계를 대신할 수 있는 방법으로 페이퍼-프로토타이핑 기법을 적용하여 아날로그 방식으로 구현할 수 있도록 하였고, 개발자 중심의 개발이 아니라 사용자가 개발에 적극 참여하는 방식의 사용자 중심디자인 모델을 기반으로 하였다. 교육의 효과를 검증하기 위하여 학습자의 응용 프로그램 개발 전후의 개념 모형을 심성모형 이론을 적용하여 측정 분석하였다. 본 연구에서 제안한 프레임워크는 학교 현장에서 응용 프로그램 개발교육에 대한 새로운 접근 방법이 될 것으로 기대한다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제25권4호
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• pp.295-303
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• 1999

Presented in this paper are the experimental results that measure rapid prototyping (RP) errors in 3D medical models. We identified various factors that can cause dimensional errors when producing RP models, specifically in maxillofacial areas. For the experiment, we used a human dry skull. A number of linear measurements based on landmarks were first obtained on the skull. This was followed by CT scanning, 3D model reconstruction, and RP model fabrication. The landmarks were measured again on both the reconstructed models and the physical RP models, and these were compared with those on dry skull. We focused on major sources of errors, such as CT scanning, conversion from CT data to STL models, and RP model fabrication. The results show that the overall error from skull to RP is $0.64{\times}0.36mm(0.71{\times}0.66%)$ in absolute value. This indicates that the RP technology can be acceptable in the real clinical applications. A clinical case that has applied RP models successfully for treatment planning and surgical rehearsal is presented. Although the use of RP models is rare in the medical area yet, we believe RP is promising in that it has a great potential in developing new tools which can aid diagnosis, treatment planning, surgical rehearsal, education, and so on.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.854-861
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• 2005

The functional behavior of a portable consumer electronic (PCE) product is nearly all expressed with human-machine interaction (HMI) tasks. Although physical prototyping and computer aided design (CAD) software can show the appearance of the product, they cannot properly reflect its functional behavior. In this paper, we propose a virtual prototyping (VP) system that incorporates virtual reality and HMI functional simulation in order to enables users to capture not only the realistic look of a PCE product but also its functional behavior. We obtain geometric part models of the product and their assembly and kinematics information with the help of CAD and reverse engineering tools, and visualize them with various display tools. We adopt state transition methodology to capture the HMI functional behavior of the product into a state transition chart, which is later used to construct a finite state machine (FSM) for the functional simulation of the product. The FSM plays an important role to control the transition between states of the product. The proposed VP system receives input events such as mouse clicks on buttons and switches of the virtual prototype model, and it reacts to the events based on the FSM by activating associated activities. The VP system provides the realistic visualization of the product and the vivid simulation of its functional behavior. It can easily allow users to perform functional evaluation and usability testing. Moreover, it can greatly reduce communication errors occurring in a typical product development process. A case study about VP of an MP3 player is given to show the usefulness of the proposed VP system.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.892-898
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• 2008

3차원 쾌속 조형법은 컴퓨터에 저장되어있는 객체 데이터를 이용하여 시제품을 제작하는 기술로써, 기존의 나무나 클레이, 혹은 주조 제작방식과는 달리 원하는 위치에 요구되는 재료를 직접 적층함으로써 원형제품을 제작함을 특징으로 한다. 스테레오리쏘그래피, 용융 점착법, 선택적 레이저 소결법, 판상 제작법 등의 다양한 3차원 쾌속 조형법이 개발되었으나, 그 중에서 잉크젯을 통한 3차원 쾌속 조형법은 잉크화된 조형재료를 통해 구조적으로 기능이 가능한 원형제품의 제작이 가능하다는 특징이 있다. 그러나, 기능성 원형제품의 제작을 위해서는 잉크의 고농도화가 요구되며, 이로 인해 잉크 점도가 상승되어 젯팅 신뢰성이 저하되는 문제점이 있었다. 본 논문에서는 3차원 쾌속 조형법을 위한 최적 젯팅조건을 도출하기 위해 슬러리 타입 세라믹 상변화 잉크의 음파 전달속도 측정과 음파 전달속도가 젯팅에 미치는 영향을 고찰하도록 한다.