• Design & Manufacturing
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• 제2권1호
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• pp.33-38
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• 2008

As consumer in optics, electronics, aerospace and electronics industry grow, the demand for ultra precision aspherical surface lens increases higher. Precision turning with single-diamond tools has a long history of development for fabrication of optical quality surfaces since the advent of aerostatic rotary spindles and precise linear motion guide ways. To enhance the precision and productivity of ultra precision aspherical surface micro lens, the following specification of ultra precision grinding system is required: the highest rotational speed of the grinder is 100,000rpm and its turning accuracy is $0.1{\mu}m$, positioning accuracy is $0.1{\mu}m$. The development process of the grinding system for the ultra precision aspherical surface micro lens for optoelectronics industry is introduced. In the work reported in this paper, an intelligent grinding system for ultra precision aspherical surface machining was designed by considering the factors affecting the surface roughness and profiles accuracy. An aerostatic form was adopted to build the spindle of the workpiece and the spindle of grinder and ultra precision LM guide way was adopted in this system. And this paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. It results was that a form accuracy of $0.6{\mu}m$ P-V and a surface roughness of $0.006{\mu}m$ Rmax.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2518-2520
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• 1998

Silicon can be reactive ion etched (RIE) either isotropically or anisotropically. In this paper, a new micromachining technology combining these two etching characteristics is proposed. In the proposed method, the fabrication steps are as follows. First. a polysilicon layer, which is used as the bottom electrode, is deposited on the silicon wafer and patterned. Then the silicon substrate is etched anisotropically to a few micrometer depth that forms a cavity. Then an PECVD oxide layer is deposited to passivate the cavity side walls. The oxide layers at the top and bottom faces are removed while the passivation layers of the side walls are left. Then the substrate is etched again but in an isotropic etch condition to form a round trench with a larger radius than the anisotropic cavity. Then a sacrificial PECVD oxide layer is deposited and patterned. Then a polysilicon structural layer is deposited and patterned. This polysilicon layer forms a pivot structure of a rocker-arm. Finally, oxide sacrificial layers are etched away. This new micromachining technology is quite simpler than conventional method to fabricate joint structures, and the devices that are fabricated using this technology do not require a flexing structure for motion.

• Archives of Plastic Surgery
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• 제36권5호
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• pp.642-648
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• 2009

Purpose: Hexadactyly without thumb is a rare congenital anomaly of the hand where six triphalangeal digits are symmetrically distributed without thumb. Contrary to mirror hands, triphalangeal six digits are symmetrically distributed on each side at the midline with well - differentiated carpal bones, extensor tendons, one ulnar and one radius. The authors developed a new surgical technique based on a three - dimensional concept to correct the hexadactyly and applied to 2 cases of hexadactyly with good functional and aesthetic results. Here we document the surgical technique and its result. Methods: A 16 month old male patient visited our clinic with chief complaints of bilateral hexadactyly deformity. On physical examination most radial first and second digits showed no opposition and adduction motion on both side hands. Radiography showed 6 triphalangeal digits with normal development of carpal, radial and ulnar bone. Right side abnormality was corrected by removal of most radial side extra - digit, rotation and migration of 2nd ray to thumb position and creation of 1st web by transposing a mid - palm based rectangular palmar flap as in Snow & Littler procedure which has been being applied for correction of 1st web syndactyly in cleft hand deformity. Seven months later, left side abnormality was also corrected with the same procedure. Results: Postoperative appearances of the both hands were satisfactory. Flexion, extension, opposition and grasping were possible with the pollicized 2nd ray. Pinching power was 3.0 kg 15 months after surgery and 2.5 kg 22 months after in right hand respectively. Conclusion: In correction of hexadactyly deformity, satisfactory aesthetic and relevant functional results can be expected with authors' newly developed technique: removal of most radial digit, rotation and migration of 2nd digit to thumb position as well as creation of the 1st web space by transposition of mid - palm based rectangular flap.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권6호
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• pp.1516-1529
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• 2023

In this paper, a motor gearbox fault-detection system based on a hierarchical flow-based model is proposed. The proposed system is used for the anomaly detection of a motion sound-based actuator module. The proposed flow-based model, which is a generative model, learns by directly modeling a data distribution function. As the objective function is the maximum likelihood value of the input data, the training is stable and simple to use for anomaly detection. The operation sound of a car's side-view mirror motor is converted into a Mel-spectrogram image, consisting of a folding signal and an unfolding signal, and used as training data in this experiment. The proposed system is composed of an encoder and a decoder. The data extracted from the layer of the pretrained feature extractor are used as the decoder input data in the encoder. This information is used in the decoder by performing an interlayer cross-scale convolution operation. The experimental results indicate that the context information of various dimensions extracted from the interlayer hierarchical data improves the defect detection accuracy. This paper is notable because it uses acoustic data and a normalizing flow model to detect outliers based on the features of experimental data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• 영상문화
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• 제19권
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• pp.189-221
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• 2012

본 논문은 영화의 출현 이전 19세기 시각기구들의 발전과정에 주목하여 동영상의 원리와 동영매체가 발전된 과정을 탐구하고자 한다. 이를 위해 본 논문은 잔상 이론이 본격적으로 연구되기 시작한 1820년대부터 1895년 영화의 발명에 이르기까지 시각 및 동영상기구들의 발전단계를 살펴보고, 동영상의 인지 원리로 알려진 '잔상효과(殘像效果)'(afterimage effect) 이론을 검토하고자 한다. 19세기 시각기구들은 소마트로프(Thaumatrope)-페나키스티스코프(Phenakistiscope) / 스트로보스코프(Stroboscope)-조이트로프(Zoetrope) -프락시노스코프(Praxinoscope)로 발전되었고, 1892년 투영식 프락시노스코프가 처음으로 동화(動畫)(moving pictures)를 스크린 위에 '움직임의 환상'(illusion of motion)으로 보여주었다. 이러한 시각기구들은 '잔상의 지속' 내지 '잔상효과'라고 알려진 이론을 근거로 발달되었지만, 20세기 초반 연구에 의하면, 동영상의 인지는 기존의 잔상 이론만으로는 설명이 부족하다는 것이 드러났다. 동영상의 인지에 관해 가장 유력한 설명 모델로서 인정받는 것은 인지심리학자 막스 베르트하이머(Max Wertheimer 1880-1943)의 1912년 실험·연구에 근거하는 '파이 현상'(Phi-phenomenon)이다. 또한, 동영상의 인지에서는 인간 눈의 특수한 시각적 인지체계가 작용하고 있으므로, 동영상의 인지 원리는 과학 지식과 더불어 재검토될 필요가 있다.