• Tribology and Lubricants
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• 제36권5호
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• pp.267-273
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• 2020

This study experimentally investigates hydrophobic surfaces fabricated via additive manufacturing. Additive manufacturing, commonly known as 3D printing, is the process of joining materials to fabricate parts from 3D model data, usually in a layer-upon-layer manner. Digital light processing is used to fabricate hydrophobic surfaces in this study. This method uses photo-curable resins and ultraviolet (UV) sources. Moreover, this technique generally has faster shaping speeds and is advantageous for the fabrication of small components because it enables the fabrication of one layer at a time. Two photo-curable resins with different compositions are used to fabricate micro-patterns of hydrophobic surfaces. The resins are composed of a photo-initiator, monomer, and oligomer. Experiments are conducted to determine suitable process conditions for the fabrication of hydrophobic surfaces depending on the type of resin. The most important factors affecting the process conditions are the UV exposure time and slice thickness. The fabrication capability according to the process conditions is evaluated using the side and top views of the micro-patterns observed using a microscope. The micro-patterns are collapsed and intertwined when the exposure time is short because sufficient light (heat) is not applied to cure the photo-curable resin with a given slice thickness. On the other hand, the micro-patterns are attached to each other when the exposure time is prolonged because the over-curing time can cure the periphery of a given shape. When the slice is thicker, the additional curing area is enlarged in each slice owing to the straightness of UV light, and the slice surface becomes rough.

• 한국기계가공학회지
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• 제9권6호
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• pp.87-94
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• 2010

In this paper, a new simulator of the biped robot for planning walking patterns was showed. And this simulator(MHBiped) is able to not only visualize the plan of patterns but also verify whether a biped robot design is suitable. In addition, MHBipd can modify various kinds of walking parameters and the trajectory of biped robot. Therefore, a new biped robot can be designed easily by the this simulator before you apply to a robot. As a result, a well-balanced parameters of walking patterns watching the movement of CG and ZMP can be obtained. Walking patterns should be changed according to both the existence of obstacles and conditions of ground and it can be described by the trajectory of hip and ankles. All those trajectorys can be also obtained by the cubic spline functions and the way of modeling walking patterns. The results of simulator, the movement function of CG and ZMP, the cubic spline functions and modeling of biped robot were introduced in this paper. And the effectiveness of this simulator was confirmed by the simulations.

• 한국기계가공학회지
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• 제14권3호
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• pp.124-130
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• 2015

The purpose of this study is to investigate friction characteristics according to micro-dimple patterns. The surface texturing of micro-dimple patterns was tested to examine the friction of pin-on-disk using flat-on-flat contact geometry. The patterns of both dimple circle and groove pattern were adopted to carry out the effect of those ones. In the low loads, such as 13.8N and 27.7N, the friction coefficients of groove pattern were lower than those of dimple circle pattern. In many other comparisons of normal loads, the groove pattern had lower friction forces, which showed the effect of surface texturing. The relationship between sliding time and friction forces showed that the increase of friction forces of groove pattern were relatively lower than those of dimple pattern. In conclusion, the dimple patterns of dimple-circle pattern and groove pattern strongly contributed to reducing the friction between contacting materials.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2002년도 춘계학술대회 논문집
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• pp.45-52
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• 2002

Artificial neural networks (ANN) have been successfully used for classifying remotely sensed imagery. However, ANN still is not the preferable choice for classification over the conventional classification methodology such as the maximum likelihood classifier commonly used in the industry production environment. This can be attributed to the ANN characteristic built-in stochastic process that creates difficulties in dealing with unequally represented training classes, and its training performance speed. In this paper we examined some practical aspects of training classes when using a back propagation neural network model for remotely sensed imagery. During the classification process of remotely sensed imagery, representative training patterns for each class are collected by polygons or by using a region-growing methodology over the imagery. The number of collected training patterns for each class may vary from several pixels to thousands. This unequally populated training data may cause the significant problems some neural network empirical models such as back-propagation have experienced. We investigate the effects of training over- or under- represented training patterns in classes and propose the pattern repopulation algorithm, and an adaptive alpha adjustment (AAA) algorithm to handle unequally represented classes. We also show the performance improvement when input patterns are presented in random fashion during the back-propagation training.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 1991년도 제3회 한글 및 한국어정보처리 학술대회
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• pp.196-208
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• 1991

This study focused on the role of prefabricated speech (routines and patterns) in the L2 acquisition process. The data for this study consisted of spontaneous speech samples and various observational records of three Korean children learning English as L2 in a nursery school. The specific questions addressed here were: (1) What routines, patterns, and creative constructions did the children use? (2) What was the general trend in the three children's use of routines, patterns, and creative constructions over time? The data were collected over a period of one school year by observing the children in their school. The findings were discussed from the perspective of human information processing. This study found that prefabricated speech played a significant role in the three children's L2 acquisition. The automatic processing of prefabricated speech appeared to enable the children to reduce the burden on their information processing systems, which allowed the saved resources available for other language development activities. Also, the children's language development was evident in their increase in the use of patterns. The children were moving from heavy dependence on wholly unanalyzed routines to increased use of partly unanalyzed patterns. This increased control was the result of an increase in procedural knowledge.

• Journal of Information Technology Applications and Management
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• 제9권2호
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• pp.1-16
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• 2002

Recently, neural network methods have been studied to find out more valuable information in data bases. But the supervised learning methods of neural networks have an overfitting problem, which leads to errors of target patterns. And the unsupervised learning methods can distort important information in the process of regularizing data. Thus they can't efficiently classify data, To solve the problems, this paper introduces a hybrid neural networks HACAB(Hybrid Algorithm combining a Competition learning model And BP Algorithm) combining a competition learning model and 8P algorithm. HACAB is designed for cases which there is no target patterns. HACAB makes target patterns by adopting a competition learning model and classifies input patterns using the target patterns by BP algorithm. HACAB is evaluated with random input patterns and Iris data In cases of no target patterns, HACAB can classify data more effectively than BP algorithm does.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.86-90
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• 2006

Nanoimprint lithography (NIL) is a novel method to fabricate nanometer scale patterns. It is a simple process with low cost, high throughput and high resolution. NIL process creates patterns by the mechanical deformation of imprint resist and physical contact process. This physical contact process causes the stiction between the resist and the stamp. Stiction becomes a key issue especially in the stamps including narrow pattern size and wide area during NIL process development. The antistiction layer coating using fluorocarbon is very effective to prevent this problem and ensure successful NIL. In this paper, the concept of antistiction coating is explained and different preparation methods for nanoimprinting are briefly discussed.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.71-71
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• 2003

Hot embossing has been widely accepted as an alternative to photolithography in generating patterns on polymeric substrates. The optimization of embossing process should be accomplished based on polymer substrate materials. In this paper, the effect of polymer substrates on nano scale hot embossing process was studied. Silicon molds with nano size patterns were fabricated by e-beam direct writing. Molds were coated with self-assembled monolayer (SAM) of (1, 1, 2.2H -perfluorooctyl)-trichlorosilane to reduce the stiction between mold and substrates. For an embossing, pressure of 55, 75 bur, embossing time of 5 min and temperature of above transition temperature were peformed. Polymethylmethacrylates (PMMA) with different molecular weights of 450,000 and 950,000, MR-I 8010 polymer (Micro Resist Technology) and polyaliphatic imide copolymer were applied for hot embossing process development in nano size. These polymers were spun coated on the Si wafer with the thickness between 150 and 200 nm. The nano size patterns obtained after hot embossing were observed and compared based on the polymer properties by scanning electron microscopy (SEM). The imprinting uniformity dependent on the Pattern density and size was investigated. Four polymers have been evaluated for the nanoimprint By optimizing the process parameters, the four polymers lead to uniform imprint and good pattern profiles. A reduction in the friction for smooth surfaces during demoulding is possible by polymer selection.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권5호
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• pp.346-356
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• 2005

디자인 패턴은 지난 10년 이상 소프트웨어 공학 영역에서 활발하게 연구되어 여러 유형의 디자인 패턴이 정의되었다. 그러나 이들 패턴은 자료구조와 알고리즘에 비해 소프트웨어 개발 과정에 빈번하게 사용되지 못하고 있다. 더욱이 CBD96, RUP, MaRMI III 같은 CBD 방법론들은 분석, 설계, 개발 과정중에 디자인 패턴을 선정하고 적용하는 방법이 언급되어 있지 않다. 본 논문에서는 GoF, J2EE 패턴 카타로그에 제시된 디자인 패턴을 중심으로 응용 소프트웨어를 개발하기 위해 분석, 설계, 개발 단계에 적용되는 디자인 패턴을 효과적으로 선정하는 프로세스를 제시한다. 제시된 프로세스를 항공업무 어플리케이션 개발 과정에 적용하여 패턴 기반 소프트웨어를 개발해 나가는 효과적인 방법을 보이고 RUP와의 차이점 및 유용함을 제시한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.467-471
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• 2005

In this paper, experimental methods about the flow behavior of thin polymer film by various edge patterns in the spin coating process for stable cover layer coating of a blu-ray disc is described. The blu-ray disc, a next-generation optical disc format over 25GB, consists of a 1.1m thick substrate and a 0.1mm tick cover layer. Generally, cover layer on the blu-ray disc is made by the polymer spin coating process. However, it is hard to secure sufficient coating uniformity around the rim on the cover layer. In order to get the uniform thickness deviation and to minimize the bead around the rim, the edge of the disc substrate can be modified into various patterns, such as normal plain, trench, step and chamfer pattern, etc, around the rim on the disc and experimented with various parameters, such as surface tension, viscosity, coating time, temperature and rotation speed, etc. And the optimal shape of the rim was tried to get by 3 dimensional computer simulation of the polymer expulsion process.