• 소성∙가공
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• 제11권7호
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• pp.581-588
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• 2002

Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.

• 한국안전학회지
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• 제27권5호
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• pp.42-48
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• 2012

Peel-tension fatigue experiments were conducted for investigating on fatigue strength of mechanical press joints of SPCC steel sheet used in the field of the automobile industry. In addition, finite element method analysis on the peel-tension specimen was conducted using HyperMesh and ABAQUS softwares. The cold rolled mild steel was used to join the T-shaped peel-tension specimen with a button diameter of 5.4 mm and a punch diameter of 8.3 mm. The fatigue limit load amplitude was found to be 112.4 N at the number of cycles 106, indicating that the ratio of fatigue limit load to static peel-tension strength was about 8%. This value suggests that the mechanical press joint is highly vulnerable to peel-tension load rather than to tensile-shear load, considering that the ratio of fatigue limit load to static tensile-shear strength was about 43%. Fatigue failure mode was found to be interface-failure mode.

• 한국정밀공학회지
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• 제25권7호
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• pp.55-63
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• 2008

Fine blanking is a process of press shearing which makes it possible to produce the thick sheet metal of the finished surface and the close dimensional accuracy over the whole material thickness in the single blanking operation. In this paper, a plate holder of automotive seat recliner is manufactured by FCF(Flow Control Forming) method using the conventional mechanical press instead of the fine blanking press. Main processes for manufacturing of the plate holder by FCF method are embossing, half blanking and trimming processes. Optimal clearance, stripper force and counter force to increase the dimensional accuracy of the plate holder have been investigated by FE-analysis. As a result of FE-analysis, the clearance for both embossing and half blanking processes was -2%t and the forces of stripper and counter were 25ton and 15ton, respectively. After manufacturing the plate holder by FCF method, the measured dimensional characteristics have been compared with the required specifications as the final product. Although the dimensional accuracy of the plate holder manufactured by FCF method was a little inferior to that by fine blanking process, it was satisfactory in a general sense.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1453-1458
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• 2009

본 논문은 중공을 가진 판재 두 매를 결합하기 위하여 중공 주위를 따라 기존 레이저 용접법 대신 기계적 프레스 결합법을 적용하는 것에 관한 연구이다. 이를 통해 레이저 용접을 적용했을 때 불가피하게 발생하는 열 변형을 효과적으로 없앨 수 있다. 유한요소해석을 통하여 중공형 판재를 기계적으로 결합시킬 수 있는 금형 설계 방법을 제안하였다. 기계적 결합력을 최대화시키는 데 관련 있는 다섯 가지 설계인자를 선택하여 다꾸치 실험법을 적용한 결과 성형 깊이와 펀치모서리 반경이 가장 크게 영향을 미치는 인자로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.498-502
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• 2004

In a link-motion mechanism, numerous links are interconnected and each link executes a constrained motion at a high speed. Due to the complicated constrained motions of the constituent links, dynamic unbalance forces and moments are generated and transmitted to the main frame. Therefore unwanted vibration is produced. This degrades productivity and precise work. Based on constrained multi-body dynamics, the kinematic analysis is carried out to enable design changes to be made. This will provide the fundamental information for significantly reducing dynamic unbalance forces and moments which are transmitted to the main frame. In this work, a link-motion punch press is selected as an example of a link-motion mechanism. To calculate the mass and inertia properties of every link comprising a link-motion punch press, 3-dimensional CAD software is utilized. The main issue in this work is to eliminate the first-order unbalance force and moment in a link-motion punch press. The mass, moment of inertia link length, location of the mass center in each link have a great impact on the degree of dynamic balancing which can be achieved maximally. Achieving good dynamic balancing in a link motion punch press is quite essential fur reliable operation at high speed.

• 소성∙가공
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• 제13권8호
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• pp.689-695
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• 2004

This paper is concerned with the analysis of the forming load characteristics of a forward-backward can extrusion process. The analysis in this paper is extended to the selection of press frame capacity for producing efficiently final product at low cost. The possible extrusion processes to shape a forward-backward can part with different outer diameters are categorized to investigate quantitatively the forming load, forming energy and maximum pressure exerted on the die-material interface. The categorized processes are composed of combined and/or some basic extrusion processes. After the analysis of the forming load characteristics, the frame capacity of press suitable for a selected process could be determined along with securing the load capacity and with considering productivity. In addition, it is also suggested that different load capacities be selected for different dimensions of a part such as the wall thickness in forward direction. The work in this paper could be a good reference for analysis of complex extrusion and selection of proper frame capacity of press to achieve low production cost and thus high productivity.

• Journal of Advanced Marine Engineering and Technology
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• 제16권3호
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• pp.51-57
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• 1992

Authors had analyzed the Press machine's vibrational characteristics by Substructure Synthesis Method. This paper discribes the structural Dynamic Optimization for the machine using Sensitive Analysis Method. The substructure synthesis method and sensitive analysis methods are used for the vibration analysis and structural modification. The results obtained are as follows ; 1. The tooling precision of the press machine is ruled by the bending vibration of the slide. 2. The structural Modification Method for minimizing impact responses is proposed, and modal analysis and sensitive analysis method are introduced to solve it. 3. The impact responses of running machine were reduced to 40% of the unmodified machine by using the proposed method.

• 한국콘텐츠학회논문지
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• 제13권4호
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• pp.73-85
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• 2013

이 연구는 온라인 사회자본 형성이라는 개념을 이용하여 지역 언론사의 웹사이트와 소셜미디어 이용을 분석하였다. 언론사의 온라인 사회자본을 웹1.0으로서 홈페이지와 웹2.0으로서 소셜미디어로 나누어 대응 분석을 통해 시각화하였다. 즉 홈페이지에 나타난 웹 피쳐를 분석하고, 소셜미디어의 소셜피쳐와 대표성을 갖는 트위터 이용의 네트워크 구조를 검토하는 것이 목적이다. 온라인 사회자본으로서 웹사이트는 커뮤니케이션, 정보제공, 비즈니스의 측면에서 역할을 하였다. 영남지역 언론사들의 웹페이지 메인에 소셜미디어를 이용해 각각 다른 형태로 웹 피쳐를 통해 네트워크를 확장하려고 하였다. 또한 중앙언론사가 모든 플랫폼을 균형 있게 이용한 반면, 영남언론사는 트위터에 치중되어 있었으며 트위터, 유튜브, 페이스북 순서로 소셜피쳐를 활용하였다.

• 한국컴퓨터정보학회논문지
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• 제25권4호
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• pp.183-188
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• 2020

본 연구의 목적은 빅데이터를 활용한 한국 특수경비에 관련에 대한 언론보도 분석을 통한 학문적 발전과 특수경비산업의 도약을 위한 발전방안의 제시하는 데 주된 목적을 두고 있다. 연구방법은 빅카인즈 프로그램을 활용한 '특수경비', '특수경비원'에 대한 연관어 분석 및 키워드 트랜드 분석을 실시하였다. 특수경비산업의 시대적 구분에 따라 성장기(양적), 성장기(질적)으로 구별하여 분석한 결과 총기휴대, 국가중요시설, 정규직에 관련된 언론의 보도와 노출이 많았던 것으로 나타났다. 이는 일반경비원과 달리 특수경비원은 국가중요시설에서 총기를 휴대하거나 사용할 수 있도록 법률이 개정됨에 따라 언론보도가 높게 나타났다. 또한 오남용에 대한 부작용을 우려하는 언론의 관심이 많았던 것으로 보여진다. 질적 성장기에는 특수경비원의 열악한 처우 개선 및 저임금, 불안정한 신분제도의 개선을 위한 정규직 전환에 관한 언론보도가 높게 나타났다. 따라서 특수경비업무의 지속적인 발전과 전문성 및 업무효율성을 향상시킬 필요성이 강조된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.367-370
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• 2009

Recently, ultra high strength products can be manufactured by the hot press forming process of Boron steel in automotive and electronics industries. In order to get high strength, the hot press forming should be accompanied by quenching process inducing phase transformation. In the study, the heat conductive die and the cooling channel were designed by the numerical simulation and the effect of three different parameters were determined to improve cooling characteristics.