• Applied Microscopy
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• v.41 no.3
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• pp.147-154
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• 2011

Backscattered electrons (BSE) are generated at the impact of the primary electron beam on the specimen. BSE imaging provides the compositional contrast to resolve chemical features of sectioned block-face. A focused ion beam (FIB) column can be combined with a field emission scanning electron microscope (FESEM) to ensure a dual (or cross)-beam system (FIB-FESEM). Due to the milling of the specimen material by 10 to 100 nm with the gallium ion beam, FIB-FESEM allows the serial block-face (SBF) imaging of plastic-embedded specimens with high z-axis resolution. After contrast inversion, BSE images are similar to transmitted electron images by transmission electron microscopy. As another means of SBF imaging, a specialized ultramirotome has been incorporated into the specimen chamber of FESEM ($3View^{(R)}$). Internal structures of plastic-embedded specimens can be serially revealed and analyzed by $3View^{(R)}$ with a large field of view to facilitate three-dimensional reconstruction. These two SBF approaches by FESEM can be employed to unravel spatial association of (sub)cellular entities for a comprehensive understanding of complex biological systems.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.2
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• pp.72-79
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• 2000

A new optimal tool design model which can be minimized the resultant cutting forces under the constrains of variables was developed. The resultant cutting forces are used as the objective function and tool angles are used as the variables. Cutting experiments of tool wear and chip length using the new and conventional tools wee carried out. Tool life of optimized cutter are more increased than those of conventional cutter by 2.29 times and 2.52 times at light and at heavy cutting conditions respectively. Chip length of optimized cutter are more increased than those of conventional cutter It is considered that the decrease of the resultant cutting forces is the cause that an effective rake and shear angles by the shape of optimal cutter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.89-94
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• 1995

A16061, SB41 and SM45C was used for developing tool wear monitoring system in face milling. First of all, Neural networks of which input are 8 $_{th}$ order AR morel parameters, frequency band energies, cutting conditions was used to monitor tool wear for each material. Finally, A unified neural network, which has tensile strengths of each material as an additional input, was constructed to consider the effect three materials on the features of tool wear. It was verified that tensile strength is the one of properties of workpiece materials.s.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.169-172
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• 1995

In optmizing cutting condition for face milling operation, tool wear is an important maching factor. For the purpose of establishing the relationship between various maching factor and tool wear, cutting tests have been performed. As a result, hardness and chemical composition of workpiece material, chemical compositition and grain size of cutting tool and cutting speed have been selected as machining factor. In addition, relationship between feed rate and workpiece hardness has been observed. Prior to utilizing cutting condition recommended by 'Machining Data Hardbook(MDH)' as a Knowledge base, an analysis for the validity has been provided. Based on this analysis, tool life criteria applied by MDH has been modifiied. Finaly, using MDH recommended data for neural network trainning, we can compensate the result form the trained neural network for optimizing cutting condition for some given workpice and cutting tool.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.927-931
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• 1997

In process of the finish face milling of the hardended STD11 steel(H /sab r/ c50,55) by CBN tool, the optimum tool shape is suggested,which can minimize the tool fracture and by chipping by impact. The obtained results are as follows. (1) The optimal chamfer angel was about 25 .deg. , and the suitable chamfer width was 0.2mm. (2) The nose radius of tool was most excellent at 1.2mm in the viewpoint of tool wear and surface roughness. (3) Wear speed was effected by sintering method of CBN tool B.U.E

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.28-33
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• 1992

The paper describes a new mean specific cutting pressure model in order to improve the accuracy of prediction of cutting force for face milling. The new mean specific cutting pressure model produces a mean specific cutting pressure and coefficients applied to existing cutting model not by traditional method but by considering intermittence and variation of chip width according to insert cutting position to take into cutter geometry machining condition and width of workpiece, and considering a mean measure force according to spindle eccentricity and mean measure force according to spindle eccentricity and insert initial position errors.. The simulated forces in X, Y, Z directions resulted from the simulated cutting model and the new cutting model are compared with measured forces in the time end frequency domains. The simulated forces in the time and frequency domains. The simulated forces resulted from the new cutting model have a good degreement with measured forces in comparison with these resulted from the existing cutting model

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.451-456
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• 1995

This study investigates the feasibility of the real time detection of tool breadage in face milling operation. The proposed methodology using an ART2 neural network overcomes a cumbersome task in terms of the learning or determining a threshold value. The features taken in the researchare the AR parameters modelled from a RLS, and those are proven to be good features for tool breakage from experiments. From the results of the off line application, we can conclude that an ART2 neural network can be well applied to the clustering of tool states in real time regardless of the unsupervised learning.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.79-89
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• 1998

In determining optimal cutting condition for face milling operation, tool wear is an important factor. For the purpose of establishing the relationship between various machining factors and tool wear, cutting tests have been performed. As a result, hardness and chemical composition of workpiece material, chemical composition and grain size of cutting tool and cutting speed have been selected as machining factors. In addition, relationship between feed rate and workpiece hardness has been observed. Prior to utilizing cutting conditions recommended by ‘Machining Data Handbook(MDH)’ as a knowledge base, an analysis for the validity of the MDH has been provided. Based on this analysis, tool life criteria applied by MDH has been modified. Finally, using MDH recommended data for neural network trainning, the results from the trained neural network for optimal cutting condition for some given workpiece and cutting tool can be used as reference cutting conditions.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.4
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• pp.28-38
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• 1995

The flank wear at the minor cutting edge significantly affects the geometric accuracy and surface roughness in finish machining. A fuzzy estimator based on a fuzzy inference algorithm with a max-min composition rule is introduced to evaluate the minor flank wear length. The features sensitive to minor flank wear are extracted from the dispersion analysis of a time series AR model of the feed directional acceleration signal. These features, dispersions, are used for constructing linguistic rules, and then the fuzzy inferences are carried out with test data sets collected under various cutting conditions. The proposed system turns out to be effective for estimating minor flank wear length.

• Applied Microscopy
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• v.40 no.4
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• pp.177-183
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• 2010

A focused ion beam (FIB) system produces a beam of positive ions (usually gallium) which are heavier than electrons and can be focused by electrostatic lenses into a spot on the specimen. With its ability milling of the specimen material by 10 to 100 nm with each pass of the beam, FIB is widely adopted in materials science, semiconductor industry, and ceramics research. Recently, FIB has been increasingly employed in the field of biomedical sciences. Here we provide a brief introduction to FIB and its applications for a wide variety of biomedical research. The surface of specimen can be in situ processed and quasi-real time visualized by two beam combination of FIB and field emission scanning electron microscope (FESEM). Due to its milling process, internal structures can be exposed and analyzed: yeast cells, fungus-inoculated wheat leaf, mannitol particles in inhalation aerosols, and oyster shell. Serial blockface tomography with the system kindles 3-dimensional reconstruction researches in the realm of nervous system and life sciences. Two-beam system of FIB/FESEM is a versatile tool to be utilized in the biomedical sciences, especially in 3-dimensional reconstruction studies.