• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.80-83
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• 2003

Transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer, generated during the polymer filling, deteriorates transcribability because the solidified layer prevents the polymer melt in filling the sub-micro patterns. Therefore, the development of the solidified layer during filling stage of injection molding must be delayed. For this delay, passive heating by insulation layer has been used. In the present study, to examine the development of the solidified layer delayed by passive heating, the flow of polymer melt with passive heating was analyzed. Passive heating markedly delayed the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micro patterns. As a result, we predict that passive heating can improve transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mold and measured the transcribability.

• 소성∙가공
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• 제13권1호
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• pp.39-44
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• 2004

Transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer, generated during the polymer filling, deteriorates transcribability because the solidified layer prevents the polymer melt from filling the sub-micro patterns. Therefore, the development of the solidified layer during filling stage of injection molding must be delayed. For this delay, passive heating by insulation layer has been used. In the present study, to examine the development of the solidified layer delayed by passive heating, the flow of polymer melt with passive heating was analyzed. Passive heating markedly delayed the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micro patterns. As a result, we predict that passive heating can improve transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mold and measured the transcribability of an optical disk substrate.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 압출 및 인발 심포지엄
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• pp.47-55
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• 1999

The microstructure of Al 6061 powder milled from rapidly solidified flake and it's extrudate were investigated. The grain size of flake was about $0.8-1.5{\mu}m$ and the powder shape was spherical due to the milling condition. In the microstructure of extrudate, the unbinded powder boundary was found the front part of extrudate and all the macroscopic defects such as boundary defect, holes or cracks was not observed except the front part. It was found that the extrudate except 60cm of front part was useful part.

• 한국주조공학회지
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• 제15권4호
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• pp.408-415
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• 1995

Polycrystalline Al-Cu ribbons were produced by planar flow casting(PFC). Solidification behavior and microstructual changes of the ribbons have been investigated as a function of ribbon thickness and processing parameters. The solidification front velocity, V varies within the ribbon, decreasing with increasing the distance, S from the wheel-contact surface, as $V=17.6S^{-1}$. In Al-4.5wt%Cu alloy, rapid decrease in solidification velocity toward the free surface causes a change in solidification morphology from planar to cellular, and finally, to dendritic. The length and inclination of columnar grains solidified with planar front were related to the wheel velocity. The transition from particulate degenerate eutectic structure to regular lamellar eutectic structure was observed to be caused by a difference of the relative growth velocites of ${\alpha}-Al$ and ${\theta}$ during solidification in the Al-Cu eutectic alloy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.174-177
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• 2000

In this paper, The bulging behavior of the solidified shell in continuously cast slabs have been numerically analyzed using three-dimensional elasto-plastic and creep finite element method Three-dimensional model has been applied in order to investigate the effect of the narrow face shell on restraining the bulging deflection. Solidification analysis are carried out by two-dimensional finite difference method. In this way, strains occurring at the solidification front near the narrow face of the slab, as well as those occurring in the board face have been computed. The adequacy of the model has been checked against the experimental results. In addition, the effect of the slab width and casting speed on the bulging are discussed.

• 한국결정성장학회지
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• 제8권1호
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• pp.187-192
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• 1998

일반적으로 재료의 응고조직은 주상정과 등축정 수지상 영역으로 이루어지는데 이것은 제품의 기계적, 물리적 성질과 밀접한 관계를 가지기 때문에 주상정-등축정 천이에 관한 많은 이론적 연구가 행하여지고 있다. 본 연구에서는 J.D. Hunt에 의하여 일방향응고시 주상정앞에서의 핵생성과 결정성장조건을 이용하여 구하여진 해석학적 주상정-등축정 조건식을 바탕으로 응고속도에 따라 변하는 분배계수와 액상선기울기를 적용하여 수정된 조건식을 구하였다. 그리고 Al-Cu합금에 대하여 응고변수인 핵생성수, 핵생성온도, 합금의 조성, 응고속도 온도기울기에 따른 천이현상의 변화를 조사하였다.

• 한국정밀공학회지
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• 제18권12호
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• pp.60-65
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• 2001

To simulate the real molding conditions, the effects of phase change and compressibility of the resin were considered in the present investigation. A modified Cross model with either an Arrhenius-type or WLF-type functional form was used for modeling viscosity of the resin. A double-domain Tait equation of state was employed to describe the compressibility of the resin during molding. The energy balance equation including latent-heat dissipation fur semi-crystalline materials was solved in order to predict the solidified layer and temperature profile. Injection molding experiments were carried out using polypropylene(PP) in the present study. Based on the comparison between experiments and simulations, it was found out the predicted pressure distributions and melt front propagations were accurate. Thus it was concluded that the program developed in this study was proved to be useful in simulations of injection molding process.

• 한국의류산업학회지
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• 제10권5호
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• pp.652-659
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• 2008

This study was designed to testify the possibility and devise the method to manipulate the 3D body scan data to produce rounded-belt pattern adaptable to hip-type variation of women in their 20's. The results of this research were as follows : Firstly, based on drop-value distribution of hip and waist girth, 151 subjects were classified into three hip-types; Type 1 (15.23%) was 'cylinder type', showing lowest drop-value, Type 2 (69.54%) was 'average type' and Type3 (15.23%) was 'hourglass type' showing highest drop-value. Secondly, using CAD program, design lines for round shape belt were set on the surface of 3D scan data of representative subject of each type. And divided 3D surfaces were flattened onto the plane by the internal tools of CAD program. The measure, 'lifting value of round belt pattern', implying the level of curve ratio of pattern was higher in back than front. This result might be linked to the fact that the hip part is more protruded than the abdomen part. And the measures also showed highest values in Type 3(hourglass type) and lowest in Type 1(cylinder type), meaning that the pattern of Type 3 showed more rounded shape than that of Type 1. This finding implied that round belt for body type having high drop-value should be shaped more curved. Thirdly, difference ratios of outline length and area between 3D curves(body surface) and 2D plane(pattern) were 4.5% and 1.3%, respectively. This result demonstrated and solidified the feasibility of designing digital garment pattern from 3D body scan data.

• 비교문화연구
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• 제29권
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• pp.113-131
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• 2012

In our days, we live in the world of image and imagination. Now we think that the images and imaginations are no more selective but indispensable elements in our life. The status of imagination is dramatically changed since 20 century. Many philosophers like G. Bachelard, G. Durand, Paul Ricoeur, H. Corbin, G. Deleuze made great contributions and we think that the studies of imagination began since 20 century. But the change of the status of imagination was not made in one day. In the long history of human life, the imagination kept his own value, and never stopped to give his influence to the human mentalities. The concept of imagination was born from the Plato's notion of phantasia. Plato thinks that the phantasia is a kind of drawing capacity in mind in the process of recognition. But the image which phantasia makes is not real one but pseudo one. So it is necessary to banish those false images from our recognition. Aristotle thought phantasia as an afterimage of object of sense. The sense is always true, but the phantasia is very possible to be an error. After Plato and Aristotle, the notion of phantasia developed into that of imagination, but it was always a problem full of contradictions. According to G. Durand, we can say, in some sense, the history of western philosophy is a kind of struggle against the image and imagination. In Middle Age, the iconoclasm tried to exclude image from their religion. Thomas Aquinas tried to explain the image by the rationalistic christianisme. In 16-17C Galilei and Descartes solidified the exclusion of imagination from the philosophy in the name of science and reason. The empiricism and positivism was the final and the most conclusive philosophies which exclude the imagination definitively from the field of philosophy. But the imagination continued his influence in the field of art. In the age of Renaissance, the imagination found his way of liberal expression, and this trend was inherited to Baroque. From the middle of 17c many philosophical theories supported the imagination by many philosophers like J.-B. Dubos, Baumgarten, A. Becq, J.-J. Rousseau etc. The Romanticism was the first significant wave which made the imagination come forward in front the art. The romanticism broke the narrow frame of rationalism and expand human's view of the world to the cosmos. From the romanticism, the imagination became a faculty which expresses the unity of human and nature. That was impossible by the rational thinking of rationalism. The concept of new imagination made a new future of human, 'the imagining conscious' and this imagining conscious provided a solid base of next generation's symbolism and surrealism.