• 반도체디스플레이기술학회지
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• 제16권1호
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• pp.91-96
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• 2017

One of the most critical aspects of the modern semiconductor industry is the quality of wafer surface, the roughness of which is mostly caused by the ingot slicing. And the grinding is supposed to be the main process to reduce the surface roughness. The vibrations of the disc surface grinder are the major problem to effectively achieve the required surface quality. In this study, the structure of a disc surface grinder was analyzed through the experiment and the computer simulation to investigate the dynamic characteristics of the machine, and further to alter the design for the improved stability. The result of the study shows that simple design alterations without alternating main body can effectively suppress the vibrations of the machine.

• 한국안전학회지
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• 제22권3호
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• pp.13-21
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• 2007

Personal and static sampling for formaldehyde, wood dust and noise monitoring, in accordance to the equipment running on the day, were carried out throughout wood panel manufacturing process. Even though the exposure level of formaldehyde and wood dust were below than exposure criteria, but the personal protective equipment(PPE) for those should be worn to everyone in the process because of its potential characteristics like carcinogenicity. Also a few local air extraction system above the cutting, grinding sections and organic blending room should be required. Most of the exposures of noise exposure were exceeded permitted exposure criteria, in case of Hopper operators, exposed to maximally 94dB(A) as LAeq 8hr, therefore active controls like PPE, monitoring, isolation etc. are necessary. The main sources of noise were caused on compressed air of the machinery, radio sound and operation noise like running machines, conveying, cutting, sawing, moving vehicles, storing and so on. For the comparison of control criteria in each country, the permitted exposure standards for above hazardous materials and noise in Korea, ACGIH and Australia were discussed. We have recognized that the Korean criteria should be discussed urgently to give the right information to employee and modified, if it is necessary.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.121-122
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• 2008

Lithium Niobate (LN:LiNbO3) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN device, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult by traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters scuh as pressure and relative velocity, were investigated for the LN CMP process. To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance and non-linear characteristic.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.541-544
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• 2001

Orthorhombic LiMnO$_2$ was synthesized by solid-state reaction using LiOH$.$H$_2$O and Mn$_2$O$_3$ as starting material. Its electrochemical properties as cathode in lithium batteries were examined. X-ray diffraction revealed that the LiMnO$_2$ compound showed a well-defined orthorhombic phase of a space group with Pmnm. The capacity of LiMnO$_2$ agreed well with its specific surface area and grinding treatment was effective in improving cycling performance. For lithium polymer battery applications, the LiMnO$_2$ cell was characterized electrochemically by charge-discharge experiments. And the relationship between the characteristics of powder and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170mAhg$^{-1}$ for LiMnO$_2$/Li cell was achieved

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2002년도 동계 학술대회 논문집
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• pp.257-262
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• 2002

본 연구에서는 분쇄방법에 따른 감초 분쇄생성물의 특성을 분석한 결과는 다음과 같다. 1. Hammer mill의 경우 d$_{80}$=750$\mu\textrm{m}$로 중간미분쇄의 입도범위를 가지며 비표면적은 0.269m/g로 분석되었고, Pin mill의 경우 d$_{80}$=600$\mu\textrm{m}$로 Hammer mill보다 입자크기는 조금 작으나 중간미분쇄영역의 입도범위를 가지며 비표면적은 0.324m$^2$/g로 분석되었고, Turbo mill은 d$_{80}$=250$\mu\textrm{m}$와 비표면적은 0.370m$^2$/g로 입자의 크기가 가장 작아 다른 분쇄기보다 분쇄능이 가장 우수한 것으로 분석되었다. 2. Hammer mill의 분쇄메커니즘은 대부분 충격, 일부 전단과 마찰에 의해 분쇄가 행해지고, Pin mill은 핀 사이에서의 전단, 충격, 마찰에 의해 분쇄된다. 즉 충격과 마찰에 의한 분쇄는 전단력에 의한 분쇄메커니즘보다 분쇄 능이나 분쇄효율이 상대적으로 낮은 것을 알 수 있었으며 주로 전단력과 충격, 반발력에 의해 분쇄가 이루어지는 Turbo mill의 분쇄능 및 분쇄 효율이 우수함을 알 수 있었다. 본 연구에 의해서 감초와 같이 섬유질을 많이 함유하고 있는 원료를 분쇄할 경우 분쇄메커니즘이 전단력인 분쇄기가 가장 적합하고, 분쇄중 소요되는 동력 면에서도 기존 분쇄기보다 우수한 Turbo mill의 분쇄조건을 확립해야 한다고 사료된다. 사료된다.

• 자원리싸이클링
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• 제10권4호
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• pp.3-9
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• 2001

박판상을 갖는 세리사이트 분말의 분쇄 효율을 향상시키기 위하여 분쇄조제 1 M $KNO_3$ 용액이 첨가된 분말을 시간에 따라 분쇄하였으며, 증류수만을 첨가하여 분쇄한 분말과 비교하였다. 분쇄된 분말의 평균 입자크기는 분쇄시간 1시간까지는 감소하다가 1시간 이후에는 미세 입자들간의 응집으로 증가하였다. 세리사이트 분말에 $1 M KNO_3$용액을 첨가한 경우 1시간 분쇄하였을 때 평균입자크기가 $1.9mu$m로 가장 작게 나타났으며 증류수를 첨가한 경우에도 1시간 분쇄 시 $2.4\mu$m로 가장 작게 나타났다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.406-413
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• 2000

The friction and wear behaviors of Magnetron Sputtered MoS$_2$films were investigated by using a pin on disk type tester which was designed and manufactured for this experiment. The experiment was conducted by using silicon nitride (Si$_3$N$_4$) as a pin material and Magnetron Sputtered MoS$_2$on bearing steel (STB2) as a disk material, under operating conditions that include different surface roughness (Polishing specimen, Grinding specimen)(2types), linear sliding velocities in the range of 22, 44, 66mm/sec (3types), normal loads vary from 9.8N, 19.6N, 29.4N(3types), corresponding to contact pressures of 1.9∼2.7GPa and atmospheric conditions of high vacuum( 1.3${\times}$10$\^$-4/Pa), medium vacuum( 1.3${\times}$10$\^$-l/Pa), ambient air(10$\^$5/Pa)(3types). We investigated fracture mechanism in magnetron sputtered MoS$_2$films with Magnetron Sputtering method in each experiment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.184-187
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• 2005

This paper is described about the technique of ultra-precision machining for optical parts in HMD system. Machining technique for PMMA and BK7 with single point diamond turning machining is reported in this paper. The main factors influencing on the machined surface quality are discovered and regularities of machining process are drawn. The purpose of our research is to find the optimum machining conditions fur cutting of PMMA and grinding of BK7. Also, apply the SPDTM technique to the manufacturing of ultra precision optical components of HMD system. Aspheric PMMA lens without a polishing process, the surface roughness of 5 nm Ra, and the form error of ${\lambda}/2\;({\lambda}=632.8nm)$ for reference curved surface 30 mm has been required.

• 한국멀티미디어학회논문지
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• 제22권7호
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• pp.790-803
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• 2019

The effects of different heat treatments on the sensory characteristics of abalones are studied in this study. In this paper, the sensory evaluation of abalone samples under different heat treatment conditions is carried out, and the evaluation results are analyzed. The three-dimensional (3D) scanning and reverse engineering are used in tooth modeling of the sensory evaluation of abalone samples under different heat treatment conditions. Besides, the chewing movement models are simplified into three modes, including the cutting mode, compressing mode and grinding mode, which are simulated using finite element simulation. The elastic modulus of the abalone samples is obtained through the compression testing using a texture analyzer to distinguish their material properties under different heat treatments and to obtain simulated mechanical parameters. Finally, taking the mechanical parameters of the finite element simulation of abalone chewing as input and sensory evaluation parameters as the output, BP neural network is established in which the sensory texture evaluation model of abalone samples is obtained. Through verification, the neural network prediction model can meet the requirements of food texture evaluation, with an average error of 9.12%.

• 한국기계가공학회지
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• 제21권2호
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• pp.123-129
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• 2022

Quartz (SiO2) has high abrasion and heat resistances and excellent chemical and mechanical properties; therefore, it is used in various industries, such as machinery, chemistry, optics, and medicine. Quartz is a high-hardness and brittle material and is classified as the topmost difficult-to-cut material, which is because of the cracking or chipping at the edge during processing. Corner wear, such as cracks and chippings that occur during cutting, is a major cause for the deterioration in the machining quality. Therefore, many researchers are investigating various techniques to process quartz effectively. However, owing to the mechanical properties of quartz, most studies have been conducted on grinding, micromachining, and microdrilling. Few studies have been conducted on quartz processing. The purpose of this study was to analyze the machining characteristics according to the machining factors during the slot machining of quartz using a cubic boron nitride (CBN) tool and to select the optimal machining conditions using the Taguchi method. The machining experiment was performed considering three process variables: the spindle speed, feed rate, and depth of cut. The cutting force and surface roughness were analyzed according to the processing conditions.