연속파형 Nd:YAG SM45C 레이저 용접의 결함 감소연구

유영태,오용석,노경보,신호준 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.1

본 연구에서는 Nd:YAG 연속파형 레이저를 이용하여 레이저 용접시 레이저빔의 출력에 대한 레이저범의 이송속도를 변화시켜 심입용접을 실시했다. 열처리를 하지 않고 용접을 실시했을 경우 매우 조대한 기공이 많이 발생하였지만 열처리 후 용접을 실시했을 때는 몇몇 미세한 기공만 발생하였다. Present investigation reports on the effect of incorporating pre-heating on the mechanical properties of laser weldi'ng joints. The Nd:YAG laser in combination with the optical fiber increase the automation and the flexibility of a whole industry. The Nd:YAG laser welding process is one of the most advenced menufacturing technologies owing to its high sped and penetration. This paper describes the weldability of Sh4456 carbon steel fox machine structural use by Nd:YAG laser. Optical microscopy SEM were performed to observe the micro structures and to determine the structures of welded zone. In addtion, mechanical propreties, were measured by tensile test to evaluate the formablity of the welded specimen. The results show that proper selection of the control parameters for per-heating technique can result the porosity and cracking of the welding significantly, and improve the welded joints mechanical properties, such as higher tensile strength and better durability.

연속파형 Nd:YAG 레이저를 이용한 SM45C 용접특성

유영태,노경보,오용석 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.2

The Nd:YAG laser in combination with the optical fiber increase the automation and the flexibility of a whole industry. The Nd:YAG laser welding process in one of the most advanced manufacturing technologies owing to its high speed and penetration. This paper describes the weldability of SM45C carbon steel for machine structural use by Nd:YAG laser. Major process parameters were position of focus, travel speed and laser power. The results showed that peneration depth of the weld was increased with increasing applied laser power. Microstructural examinations and calculations and indicated that the microstructure of the laser weld, which experienced very high heating and cooling cycle during welding process. The results of this study provide application possibility of Nd:YAG laser welding for SM45C carbon steel

구조적 문서의 효율적 검색을 위한 GDIT 자료구조에 대한 분석

김영자,권재길,박영석 경남대학교 정보통신연구소 2000 연구논문집 Vol.2 No.-

구조적 문서가 가지는 다양한 구조 정보를 활용하기 위해서는 색인 시에 문서의 구조를 나타내는 엘리먼트에 대해서 색인을 해야 한다. 이때 색인공간 오버헤드를 최소화하면서, 엘리먼트 간의 포함관계나 순서 등 문서 구조에 바탕을 둔 다양한 유형의 질의를 효율적으로 처리할 수 있어야 한다. 색인공간 오버헤드를 최소화하면서, 여러 유형의 구조 관련 질의를 효율적으로 처리할 수 있는 세가지 구조 색인 구조를 제안한 바 있다. 제안된 색인 구조는 GDIT개념에 바탕을 두고, GDIT 기반의 색인기법을 사용한다. 본 논문에서는 세 가지 색인구조에 대해 구조 관련 질의를 효율적으로 처리하기 위한 GDIT 자료구조를 제시하고, 색인 저장공간에 대한 성능을 분석 평가한다. In order to utilize a variety of structure information of structured documents, it is necessary indexing on elements representing the structure of document. When indexing, there are the requirement of low memory overhead for indexing and efficient processing of various query types based on document structure such as element containment or element order. We have been proposed three structure-based indexing structures that process a variety of query types about document structures and minimize indexing overhead. The index structures are based on GDIT(General Document Instance Tree) concept and use indexing techniques based on GDIT. In this paper, we propose the GDIT data structures for three structure-based indexing structures and evaluate the performance related on the indexing storage space.

열처리 중소기업을 위한 통합생산정보관리 시스템의 개발

박영석 경남대학교 정보통신연구소 1999 연구논문집 Vol.1 No.-

본 연구에서는 업무의 전산화와 정보의 통합화를 통하여 필요한 시점에 정보를 획득함으로서 관리의 지연으로부터 발생하는 경제적 손실을 최소화하고 가공공정의 체계화로 생산성 향상을 극대화할 수 있는 열처리 중소기업을 위한 통합생산정보관리 시스템을 구축하였다. 수주에서 판매까지의 제반 정보가 일관되고 투명하게 관리되며, 특히 열처리 가공공정을 체계적으로 관리함으로써 가공공정의 생산성 뿐 만 아니라 품질관리의 향상으로 열처리 중소기업의 강력한 경쟁력을 제공할 수 있다. We developed a network based integrated production information management system for small and medium scale heat treatment business. By getting information whenever it is needed, we can minimize the economical loss which comes from managerial delay, and maximize the productivity. The system can consistently and transparently manage the entire process of business from receiving orders to sale. And because the management of heat treatment process is systematically performed in real time, the managerial productivity, as well as the manufactural quality and productivity, is greatly improved by reducing the factors such as the setup and idle time of process, etc.

불소화방법을 이용한 탄소재료의 수소저장 연구동향

이영석 충남대학교 산업기술연구소 2006 산업기술연구논문집 Vol.21 No.1

ACF-카트리지를 이용한 수중 페놀의 흡착

이영석,문일식 순천대학교 공업기술연구소 1998 工業技術硏究所論文集 Vol.12 No.-

Adsorption characteristics of phenol in water using batch adsorption and activated Carbon Fiber (ACF)- cartridge were investigated. Adsorption capacities of the ACFs for phenol in water were found to be comparable with those of activated carbons (ACs) which have been widely used for phenol adsorption. In practices, phenol in water was rapidly removed at the first stage by ACF-cartridge. There are neither pressure changes between inlet and outlet nor shape change of cartridge. These studies enabled identification of an activated carbon fibers suitable for use in adsorption of low concentration phenol in water.

플륨 모니터링에 의한 SM45C 레이저 용접특성 평가

유영태,김재열,노경보,양동조,오용석,임기건,김지환 한국공작기계학회 2003 한국생산제조학회지 Vol.12 No.6

With the increased use of lasers in industrial welding applications, techniques for monitoring and controlling these processes become increasingly important. It is very important that we understand the dynamic behaviors of the laser induced plume in welding because the laser induced plume has considerable effects on welding efficiency and the quality of materials. As the plume fluctuation was associated with keyhole instability, unstable vapor plume indicated the process was unstable and would result in poor welds. An Infrared Themal-vision Camera can be utilized compensate for incurracies encountered in real-time monitoring during laser welding. We have results that instabilities of plume are closely dated with hot cracking and defect of laser welding.

납사분해 잔사유 및 콜타르 핏치로부터 중공형 탄소섬유의 제조 및 특성

이영석,인세진,오인석 順天大學校 1998 論文集 Vol.17 No.1

Hollow carbon fibers(HCFs) are produced from pitches which are isotropic and anisotropic(mesophase) through two cylinder annular type spinnerette specially designed to obtain hollow fibers. The amount of N₂ flowing inside of spinnerette decides both thickness of fiber and the surface area, which are affected by temperature and the winding velocity. The thicker the isotropic and mesophase pitch-based fibers are, the longer the oxidation time is, and the thinner, the shorter, however, they are easily broken. Mesophase pitch-based HCFs were oriented along the line corresponding with maximum velocity during melt spinning. It was concluded that a pitch precursor could be melt-spun, and produced uniformly into hollow carbon fibers if the spinning temperature, stabilization, and carbonization conditions were well controlled. In comparision the results of tensile testing with normal round CFs, the mechanical properties of HCFs were improved except tensile strength of isotropic HCFs.

異機種 多重프로세서 시스템의 負荷分配에 관한 硏究

朴榮碩 慶南大學校 附設 工業技術硏究所 1990 硏究論文集 Vol.8 No.-

疏結合 異機種多重프로세서 시스템(loosely coupled heterogeneous multiple processor system) 혹은 分散시스템에서 個個 프로세서의 處理能力의 多樣性에 따른 利點을 極大化하기 위해서, 本 論文에서는 分散프로그램 혹은 타스크(task) 集合의 實行行爲를 一般性을 지닌 하나의 動的確率 시스템 模型으로 模型化하고, 주어지는 프로세서의 性能因子(performance factors)에 依據해서 타스크를 프로세서에 最適으로 割當하는 그래프 理論的 負荷分配 方法을 提示한다. 提示된 負荷分配 方法에서는 最適타스크 割當 問題를 2개의 部分問題로 分類하고, 각각을 別個의 計算模型에 의해서 그래프 理論的 問題 즉, 最短經路問題(shortest path problem)와 traveling salesman 問題에 關聯한 問題로 定型化한다. 結果的으로 最適負荷分配에 관한 하나의 問題는 NP-Complete 問題임이 立證된다. In order to maximize advantage of the diverse processing power of each processor in a loosely coupled heterogeneous multiple processor system or distributed system, this paper proposes a graph theoretical method of load balancing, which makes an optimal task-to-processor assignment for a given performance factors of processors by an general model of dynamic probabilistic system which describes the execution behaviors of a distributed program or a set of tasks. The proposed method of load balancing divides the optimal task assignment problem into two subproblems, and formalizes it into graph theoretical problems, namely the ones related to shortest path problem and traveling salesman problem for different models each other. Consequently, it is verified that a problem related to optimal load balancing is NP-Complete problem.

회전 불변특성을 가지는 패턴 팽창법

박영석,최철용 慶南大學校 附設 工業技術硏究所 1998 硏究論文集 Vol.15 No.2

패턴의 팽창 경계선(dilated boundary)을 생성하는 4 방향 팽창(4-neighbor dilation) 혹은 8 방향 팽창(8-neighbor dilation)과 같은 2진 팽창법(binary dilation)에서는 회전 각도에 따라 추출된 패턴의 윤곽 형상이 매우 달라진다. 본 논문에서는 패턴의 회전에 대하여 불변특성을 지니는 교번 팽창법(alternate dilation)과 원형 마스크 팽창법(circular mask dilation)을 제안한다. 교범 팽창은 패턴의 회전 불변특성을 크게 개선한다. 그리고 원형 마스크 팽창법은 교번 팽창법 보다 더욱 강인한 회전 불변특성 제공하며 처리시간의 관점에서도 가장 우수한 특성을 지닌다. In the existing binary dilation method which generates a dilated boundary curve of pattern, such as 4-neighbor dilation or 8-neighbor dilation, The extracted curve shape is very different depending on the rotation angle of pattern. In this paper, we propose two binary dilation methods called alternate dilation and circular mask dilation, respectively. The first can greatly reduce the rotation-dependent variation of pattern. And the second provides more robust rotation-invariant characteristics than alternate dilation approach and takes the most excellent processing time.