• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.439-444
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• 2004

A new efficient intelligent machining strategy named the Steepest Directed Tree method is presented in this study, which makes surface model discrete with triangulation meshes and the cutter paths track along the tree directions. In order to formulate these algorithms practically, it is deduced the multi-stage machining approach of uncut volume caused by cutter gouging in the course of milling using flat end mill. It is systematized the checking process the cutter interference by grouping the 6 kinds of gouging types, which yields the environment of connectivity data lists including CL-data, and then the multi-stage machining strategy, that minimizes uncut area by continuously sequencing the generative subsequent CL-paths, is shamed to determine the second tool path for the next uncut area and to compose the operating multi-stage cutting processes. The completed machining system of curved surfaces is evaluated by testing the practical machining experiments which have various kinds of shape conditions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제11권2호
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• pp.7-12
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• 2012

In order to cope with the requirements of smaller patterns, larger surfaces and lower costs in the fields of displays, optics and energy, greater attentions are now being paid to the development of micro-pattern machining technology. Compared with flat moulds, large drums with micro patterns (roll moulds) have the advantages of short delivery, ease of manufacturing larger surfaces, and continuous moulding. This paper introduced the machining process technology of the roll moulds for display industry. The environmental effects were discussed and the importance of temperature maintenance was experimentally emphasized. The real time monitoring system for micro machining was introduced. A commercial solution was used to simulate the micro grooving and a deformation model of micro machined pattern was finally introduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제28권5호
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• pp.547-553
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• 2004

A hemispherical asperity moving over a flat plane is simulated based on classical molecular dynamics. The asperity and the plane consist of silicon atoms whose interactions are governed by the Tersoff three-body potential. The gap between the asperity and the plane is maintained to produce attractive normal force in order to investigate the adhesive friction and wear. The simulation focuses on the influence of crystallographic orientation of the contacting surfaces and the moving direction. It is demonstrated that the adhesive friction and wear are lower when crystallographic orientations of the contacting surfaces are different, and also depend on the moving direction relative to the crystal1ographic orientation.

• Journal of the Korean Chemical Society
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• 제18권2호
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• pp.79-84
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• 1974

Adsorption isotherms of benzene and its derivatives on Spheron 6, a graphitized carbon black, are obtained using a sensitive quartz beam microbalance. From the isotherms the molecular area of each adsorbate on Spheron 6 is calculated on the basis of nitrogen area of 16.2 $A^2$. the results show that the molecules of each species are adsorbed on Spheron 6 with the planes of benzene rings lying flat on the surfaces and doing hindered rotation.

• Tribology and Lubricants
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• 제16권3호
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• pp.166-172
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• 2000

The friction and wear characteristics of dental composite resins such as Charisma, Elitefil, TPH and Veridonfil were investigated. Furthermore, The surface characteristics examination, the analysis of contents of filler, Victors hardness and fracture toughness measurement of composite resins were preformed. The wear test applied ball to move reciprocationally on flat wear tester at room temperature. Microstructure of surfaces and worn surfaces were observed by SEM. Experimental results indicate that the friction coefficient of TPH was quite low, and the wear resistance of TPH was better than that of Charisma, Elitefil or Veridonfil at the same condition. The main wear mechanism was found to be plastic flow and abrasive wear by failure of filler's bond to the matrix.

• Journal of the Korean Wood Science and Technology
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• 제32권6호
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• pp.50-56
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• 2004

This study was conducted to investigate the performance of sound absorption type-noise barriers manufactured with a combination of wood particles used for particleboard, recycled waste newspaper, and cement. An average density of wood-combined cement board was in the range from 0.83 to 0.96 g/cm³, showing relatively low-density board. Regardless of types of cement bonded board or wooden board, the board with concave holes(凹)-formed surfaces showed greater sound absorption coefficient compared to those of flat surface boards. The board density was not related with those coefficients. Accordingly, it was concluded that concave or deep corrugated surface structure has played an important role in sound absorption for the application of sound absorption type-noise barrier.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.27-28
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• 2021

For Barrier-Free certification, the floor and ground surfaces must be finished with materials that are not slippery, flat, and have low-impact in fallis. However, the BF Certification Act does not provide specific methods to meet these regulations. In performance-based design, the responsibility of proving the performance rests with the building owner and architect, so quantitative evaluation indexes are needed to select suitable materials. Furthermore, changes in performance after completion should be checked periodically in 'As-Is' conditions. There are various methods for slips, trips and falls risk assessment, causing confusion for users. In this study, the results of previous studies on the evaluation methods of slips, trips and falls were considered closely, and each quantitative evaluation index that can be used in the new construction and maintenance phase was presented.

• Journal of the Korean Society for Precision Engineering
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• 제31권7호
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• pp.605-613
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• 2014

Scanning white-light interferometry is an important measurement option for many surfaces. However, serious profile measurement errors can be present when measuring free-form surfaces being highly curved or tilted. When the object surface slope is not zero, the object and reference rays are no longer common path and optical aberrations impact the measurement. Aberrations mainly occur at the beam splitter in the interference objective and from misalignment in the optical system. Both effects distort the white-light interference signal when the surface slope is not zero. In this paper, we describe a modified version of white-light interferometry for eliminating these measurement errors and improving the accuracy of white-light interferometry. Moreover, we report systematic errors that are caused by optical aberrations when the object is not flat, and compare our proposed method with the conventional processing algorithm using the random ball test.

• Mass Spectrometry Letters
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• 제3권1호
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• pp.18-20
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• 2012

We report observation of laser desorption/ionization (LDI) of peptides from flat surfaces of tungsten silicide ($WSi_2$). In contrast to MALDI (matrix-assisted laser desorption/ionization) and SALDI (surface-assisted laser desorption/ionization) mass spectrometry, this study did not utilize any matrices and surface nanostructures. In this work, LDI on $WSi_2$ surfaces is demonstrated to cover a mass range up to 1,600 Da (somatostatin; monoisotopic mass = 1637.9 Da). In addition, it exhibited a high sensitivity, which could detect peptides, which could detect peptides of low femtomole levels (20 fmol for angiotensin II). The observed LDI process was discussed to be largely thermal, more specifically, due to laser-induced surface heating that is most likely promoted by the low thermal diffusivity (${\kappa}$) of $WSi_2$ substrate.

• Transactions of the Korean Society of Mechanical Engineers
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• 제12권1호
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• pp.137-151
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• 1988

Thurbulent thermal convection between two plates, bottom plate is at higher temperature $T_{h}$ and the upper plate is at lower temperature $T_{i}$ is numerically investigated. Model equations are abridged Reynolds stress equations; full Reynolds stress equations are simplified to yield algebraic relations in case of mean square velocity fluctuations in vertical and horizontal directions. Boundary conditions for turbulent kinetic energy k and mean square temperature variance .thera.$^{2}$oner bar at the plate surfaces are set to be zero and those of dissipation rate of turbulent kinetic energy .epsilon. and dissipation rate of mean square temperature variance .epsilon.$_{\theta}$ are assumed at first grid point nearest to the boundary surfaces, whose values are approximated by inviscid estimates. Results show that temperature profiles are in good agreement with experimental data except transition region, in which temperature is over-predicted. Such discrepancy becomes larger as the Rayleigh number becomes smaller. Nusselt numbers, which are calculated from the temperature gradients at the boundary surfaces, are also in good agreement with experimental data.a.a.