• Journal of the Korean Society for Precision Engineering
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• v.3 no.1
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• pp.69-76
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• 1986

The measuring Method by stylus, which measures surface roughness, has been widely used since G. Schmaltz developed the first equipment of that type. Withe the resent development of the measuring method by stylus, surface foughness testing instruments of the very high magnification ratio, hundreds of thousands, are manu- factured. However, as the techniques of the high precision roughness measurement are being required, the response problems due to the tip shapes and the plastic deformations of measured surface of mild material are to be serious factors. In this study, diamond stylus of tip radius $0.5\mu\textrm{m}$, $2\mu\textrm{m}$, $5\mu\textrm{m}$ and $10\mu\textrm{m}$ were used under the measuring force of 0.01gf, 0.02gf, 0.07gf, 0.4gf and 1.6gf, and from the experimental data, maximum measured value devrements between $2\mu\textrm{mR}$ stylus and $5\mu\textrm{mR}$ stylus, $2\mu\textrm{mR}$ stylus and $10\mu\textrm{mR}$ stylus are 22% and 31%, respectively when the measured value of $2\mu\textrm{mR}$ stylus goes to $0.01\mu\textrm{m Ra}$, $\lambda$ c2.5mm. And it is shown that plastic deformations on the plastic deformations on the measured surface are proportional to W/R(W;measured force, R;stylus tip radius).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1064-1072
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• 2001

It is very important to evaluate material degradation like temper and carbide embrittlements to secure the reliable and efficient operational conditions and to prevent brittle failure in service. The extent of material deterioration can be accurately evaluated by mechanical test such as impact test or creep test. But it is almost impossible to sample a large specimen from in-service plants. Thus, the material degradation evaluation by a non-destructive method is earnestly required. Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However the program for material degradation evaluation using the grain boundary etching method(GEM) in Windows 98 domain doesnt be developed now. The aims of this paper are to develop the program and to complete the new master curve equations for the evaluation of material degradation on in-serviced high temperature components.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.445-449
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• 1997

The complex refractive indices of $Ge_2Se_2Te_5$ which show reversible phase change between the crystalline phase and an amorphous one depending upon the annealing process have been determined in the spectral range of 0.7-4.5 eV. The $Ge_2Se_2Te_5$ films were DC sputter deposited on the crystalline silicon substrate. The spectro-ellipsometry data of a thick film were analyzed following the modelling procedure where the quantum mechanical dispersion relation were used for the complex refractive indices of both the cryastalline phase $Ge_2Se_2Te_5$ and and amorphous phase $Ge_2Se_2Te_5$, respectively. On the other hand, with the surface micro-roughness layer whose effective thickness was determined from AFM analysis, the spectro-ellipsometry data were numerically inverted to yield the complex refractive index of $Ge_2Se_2Te_5$ at each wavelength. With these set of complex refractive indices, the reflectance spectra were calculated and those spectra obtained from the numerical inversion showed better agreement with the experimental reflection spectra for both the cryastalline phase and an amorphous phase. Finally, the thin $Ge_2Se_2Te_5$ film which has the optimum thickness of 26 nm as the medium for optical recording was also analyzed and the quantitative result of the film thickness and the surface microroughness has been reported.

• Journal of Korea Water Resources Association
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• v.40 no.10
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• pp.769-781
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• 2007

Factor analysis has been usually employed in reducing quantity of data and summarizing information on a system or phenomenon. In this analysis methodology, variables are grouped into several factors by consideration of statistic characteristics, and the results are used for dropping variables which have lower weight than others. In this study, factor analysis was applied for extracting primary factors influencing multi-dam system operation in the Han River basin, where there are two multi-purpose dams such as Soyanggang Dam and Chungju Dam, and water has been supplied by integrating two dams in water use season. In order to fulfill factor analysis, first the variables related to two dams operation were gathered and divided into five groups (Soyanggang Dam: inflow, hydropower product, storage management, storage, and operation results of the past; Chungju Dam: inflow, hydropower product, water demand, storage, and operation results of the past). And then, considering statistic properties, in the gathered variables, some variables were chosen and grouped into five factors; hydrological condition, dam operation of the past, dam operation at normal season, water demand, and downstream dam operation. In order to check the appropriateness and applicability of factors, a multiple regression equation was newly constructed using factors as description variables, and those factors were compared with terms of objective function used in operation water resources optimally in a river basin. Reviewing the results through two check processes, it was revealed that the suggested approach provided satisfactory results. And, it was expected for extracted primary factors to be useful for making dam operation schedule considering the future situation and previous results.

• Korean Journal of Optics and Photonics
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• v.18 no.5
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• pp.351-361
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• 2007

The samples composed of a GST thin film and the protective layers of $ZnS-SiO_2$ or $Al_2O_3$ coated on c-Si substrate were prepared by using the magnetron sputtering method. Samples of three different structures were prepared, that is, i) the GST single film on c-Si substrate, ii) the GST film sandwiched by the protective $ZnS-SiO_2$ layers on c-Si substrate, and iii) the GST film sandwiched by $Al_2O_3$ protective layers on c-Si substrate. The ellipsometric constants in the temperature range from room temperature to $700^{\circ}C$ were obtained by using the in-situ ellipsometer equipped with a conventional heating chamber. The measured ellipsometric constants show strong variations versus temperature. The variation of ellipsometric constants at the temperature region higher than $300^{\circ}C$ shows different behaviors as the ambient medium is changed from in air to in vacuum or the protective layers are changed from $ZnS-SiO_2$ to $Al_2O_3$. Since the long heating time of 1-2 hours is believed to be the origin of the high temperature variation of ellipsometric constants upon the heating environment and the protective layers, a PRAM (Phase-Change Random Access Memory) recorder is introduced to reduce the heating time drastically. By using the PRAM recorder, the GST samples are heated up to $700^{\circ}C$ decomposed preventing its partial evaporation or chemical reactions with adjacent protective layers. The surface image obtained by SEM and the surface micro-roughness verified by AFM also confirmed that samples prepared by the PRAM recorder have smoother surface than the samples prepared by using the conventional heater.

• Applied Microscopy
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• v.37 no.3
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• pp.147-156
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• 2007

The dorsal lingual papillae of Myotis macrodactylus were investigated morphologically using scanning electron microscopy. Three types of lingual papillae from Myotis macrodactylus were recognized. The filiform(Fi) papillae were distributed over the entire dorsal surface of the tongue, and they could be classified into 5 types of papillae by the shape, size and number of the protrusion. Type I was distributed on dorsal surface of the apex in the anterior region of the tongue, has a crow-like shape with ten to fifteen formed projections. Type II was located in the medial portion of the anterior region of the tongue, has an eight to ten spin-like protrusion. Type III was distributed on the medial portion of the tongue, has a scale-like papille with five to seven protrusion. Type IV was distributed on the both lateral portion of the posterior region of the tongue, has a small conical papillae, does not have needle projection. Type V have not needle projection, a large of conical papillae, on the both lateral portion of the posterior region of the tongue. Most Fu(Fungiform) papillae were distributed the both lateral region or medial portion of the posterior region of the tongue, has a round or oval shape with $40{\sim}45$ papillae. The small $(65{\mu}m)$, meddle $(75{\mu}m)$ and large $(120{\mu}m)$ fungiform papillae were distributed on dorsal surface of the apex in the anterior, the both lateral portions and medial portion of the posterior region of the tongue, respectively. Two large oval vallate (V) papillae are located in the medial portion of the posterior region of the tongue. In conclusion, the morphology of lingual papillae is useful to determine species relationship among Myotis species. It suggests that the difference of types and number of lingual papillae caused by the difference of food habit.

• Journal of the Korean Geotechnical Society
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• v.23 no.9
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• pp.5-16
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• 2007

The simple linear elastic-perfectly plastic model with soil parameters $s_u,\;E_u$ and n of undrained condition is usually applied to predict the displacement of a constructed diaphragm wall(DW) on soft soils during excavation. However, the application of this soil model for finite element analysis could not interpret the continued increment of the lateral displacement of the DW for the large and deep excavation area both during the elapsed time without activity of excavation and after finishing excavation. To study the characteristic behaviors of soil behind the DW during the periods without excavation, a series of tests on soft Bangkok clay samples are simulated in the same manner as stress condition of soil elements happening behind diaphragm wall by triaxial tests. Three kinds of triaxial tests are carried out in this research: $K_0$ consolidated undrained compression($CK_0U_C$) and $K_0$ consolidated drained/undrained unloading compression with periodic decrement of horizontal pressure($CK_0DUC$ and $CK_0UUC$). The study shows that the shear strength of series $CK_0DUC$ tests is equal to the residual strength of $CK_0UC$ tests. The Young's modulus determined at each decrement step of the horizontal pressure of soil specimen on $CK_0DUC$ tests decreases with increase in the deviator stress. In addition, the slope of Critical State Line of both $CK_0UC$ and $CK_0DUC$ tests is equal. Moreover, the axial and radial strain rates of each decrement of horizontal pressure step of $CK_0DUC$ tests are established with the function of time, a slope of critical state line and a ratio of deviator and mean effective stress. This study shows that the results of the unloading compression triaxial tests can be used to predict the diaphragm wall deflection during excavation.