• Microbiology and Biotechnology Letters
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• v.14 no.5
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• pp.399-405
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• 1986

Corn starch was saccharified without cooking in an agitated bead reaction system. Uncooked corn starch was effectively hydrolyzed even at the concentration as high as 39%(w/v). After 24 hours. the extent of saccharification reached at 92%, which corresponds glucose concentration of 425g/L. Fed-batch feeding of starch was more effective than batch feeding for saccharification of uncooked corn starch. The composition of hydrolysated of uncooked starch was analyzed. which was composed of 95% glucose, 0.7% of maltose, and 4.5% of high saccharide, similar with that of cooked starch. The hydrolysate can be successfully utilized for HFCS manufacture. The starch liquefying and saccharifying enzyme was relatively stable even be the physical impact of the attrition-milling media. The enzyme stabilizer, $Ca^{++}$, played an essential role in preventing the enzyme deactivation caused by the physical impact.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.4
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• pp.21-27
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• 2005

Recently researches for high speed machining have been actively performed. Few analytical studies, however, have been published. In this paper, a model of cutting forces is analytically studied to predict cutting characteristics in end mill process, especially considering both feed rate and spindle speed. The developed cutting model is based on Oxley's machining theory, which predicts the cutting forces from input data of workpiece material properties, tool geometry and cutting conditions. Experimental verification has been performed to verify the predictive cutting force model using tool dynamometer. It has been found that the simulation results substantially agree with experimental results.

• Journal of Powder Materials
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• v.15 no.5
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• pp.359-364
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• 2008

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.568-573
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• 2016

We explore the crystalline structure and phase transition of lithium thiophosphate ($Li_7P_3S_{11}$) solid electrolyte using electron microscopy and X-ray diffraction. The glass-like $Li_7P_3S_{11}$ powder is prepared by the high-energy mechanical milling process. According to the energy dispersive X-ray spectroscopy (EDS) and selected area diffraction (SAD) analysis, the glass powder shows chemical homogeneity without noticeable contrast variation at any specific spot in the specimen and amorphous SAD ring patterns. Upon heating up to $260^{\circ}C$ the glass $Li_7P_3S_{11}$ powder becomes crystallized, clearly representing crystal plane diffraction contrast in the high-resolution transmission electron microscopy image. We further confirm that each diffraction spot precisely corresponds to the diffraction from a particular $Li_7P_3S_{11}$ crystallographic structure, which is also in good agreement with the previous X-ray diffraction results. We expect that the microscopic analysis with EDS and SAD patterns would permit a new approach to study in the atomic scale of other lithium ion conducting sulfides.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.241-245
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• 2007

The residual stress in axial stress in the axial direction of the steel filaments has been measured by using a method based on the combination of the focused ion beam (FIB) and high resolution strain mapping program (VIC-2D). That is, the residual stress was calculated from the measured displacement field before and after the introduction of a slot along the steel filaments. The displacement was obtained by the digital correlation analysis of high-resolution scanning electron micrographs, while the slot was introduced by FIB milling with low energy beam. The present measurement revealed that the residual stress within 8% of the magnitude was persistent in the steel filaments fabricated.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.352-362
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• 2012

This paper explores the use of a variety of carbon nanoparticles to impart electrical, thermal conductivity, good frictional properties to silicon nitride matrices. We used the highly promising types of carbon as carbon nanotubes, exfoliated graphene and carbon black nanograins. A high-efficiency attritor mill has also been used for proper dispersion of second phases in the matrix. The sintered silicon nitride composites retained the mechanical robustness of the original systems. Bending strength as high as 700 MPa was maintained and an electrical conductivity of 10 S/m was achieved in the case of 3 wt% multiwall carbon nanotube addition. Electrically conductive silicon nitride ceramics were realized by using carbon nanophases. Examples of these systems, methods of fabrication, electrical percolation, mechanical, thermal and tribological properties are discussed.

• Korean Journal of Computational Design and Engineering
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• v.12 no.1
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• pp.1-7
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• 2007

In this paper, we present a machining time estimation algorithm for 5-axis high-speed machining. Estimation of machining time plays an important role in process planning and production scheduling of a shop. In contrast to the rapid evolution of machine tools and controllers, machining time calculation is still based on simple algorithms of tool path length divided by input feedrates of NC data, with some additional factors from experience. We propose an algorithm based on 5-axis machine behavior in order to predict machining time more exactly. For this purpose, we first investigated the operational characteristics of 5-axis machines. Then, we defined some dominant factors, including feed angle that is an independent variable for machining speed. With these factors, we have developed a machining time calculation algorithm that has a good accuracy not only in 3-axis machining, but also in 5-axis high-speed machining.

• Prospectives of Industrial Chemistry
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• v.23 no.5
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• pp.12-20
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• 2020

최근 층상구조를 가진 전이금속 칼코겐 화합물이 새로운 고성능 리튬이온전지 음극소재로서 주목받고 있다. 층상구조 물질들의 고성능 전극 소재 활용에 있어 박리를 이용한 정확한 층의 개수 조절은 전기화학 반응성을 증가시키고, 전극 필름 내에서의 균일한 거동을 위해서 매우 중요하다. 볼 밀링 공정은 이차전지 전극 소재 제조에 있어서 주로 물질의 분쇄나 고상 화학반응을 유도하여 합금 형태의 전극 소재 개발에 보편적으로 사용되는 공정이나, 층상구조를 가진 전이금속 칼코겐 화합물에 적용하면 층상구조 물질에 고체윤활작용을 일으켜 박리가 촉진된다. 이러한 성질을 이용하여 다양한 종류의 전이금속 칼코겐 화합물(예: MoS₂, MoSe₂, NbSe₂)에 적절한 카본 매트릭스 물질과 복합화를 통해 새로운 전극 소재를 합성하고, 이를 통해 고성능 리튬이온전지 음극 소재를 제조하는 연구 동향에 대해 보고하고자 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.327-333
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• 1999

Controlled Ca impurity implanted inner crack-like pore in the high purity alumina bi-crystal had been created by micro-fabrication technique, which includes ion implantation, photo-lithography, Ar ion milling, and hot press. The morphological change and the growth od crystals formed by heat treatment in Ca doped high purity single crystal alumina, were observed using optical microscopy. The dot was developed and hexagon like crystal appeared on inner surface of crack-like pore after heat treatment. Bar type crystals, probably CaO . $6Al_2O_3$, were observed on the inner surface of 100ppm Ca implanted specimen after 1 hour heat treatment at $1,500^{\circ}C$, but this bar type crystal disappeared after 1 hour heat treatment at $1,600^{\circ}C$. This disappearance means that there should be little increase of Ca solubility limit to alumina and/or changes of diffusion coefficient of Ca in alumina around this temperature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.