• Journal of the Korean Electrochemical Society
• /
• v.3 no.4
• /
• pp.200-203
• /
• 2000

Boron doped conducting diamond thin films were grown on Si substrate by microwave plasma chemical vapor deposition from a gaseous feed of hydrogen, acetone/methanol and solid boron. The doping level of boron was ca. $10^2ppm\;(B/C)$. The Si substrate was tilted ca. $10^{\circ}$ to make Si substrate, which have different height and temperature. Experimental results showed that different crystalline of diamond thin films were made by different temperature of Si substrate. There appeared $3\~4$ steps of different crystalline morphology of diamond. To characterize the boron-doped diamond thin film, Raman spectroscopy was used for identification of crystallinity. To survey surface morphology, microscope was used. Grain size was changed gradually by different temperature due to different height. The Raman spectrum of film exhibited a sharp peak at $1334cm^{-1}$, which is characteristic of crystalline diamond. The lower position of diamond film position, the more non-diamond component peak appeared near $1550 cm^{-1}$.

• Korean Journal of Environmental Biology
• /
• v.40 no.2
• /
• pp.157-163
• /
• 2022

We analyzed the hair microstructure of Korean small terrestrial mammals, such as Rodentia and Lagomorpha, to classify the characteristics of hair morphology. Micromys minutus showed a unicellular irregular type of medulla structures; on the other hand, the other mammals showed multicellular structures. Regarding the cuticular scale structures, the Rodentia species exhibited a narrow and broad diamond petal type, while the Lagomorpha species exhibited an elongated petal type. Interestingly, the hair cross-sections showed quite unique characteristics. We constructed hair identification keys to distinguish species with a single hair. The dichotomous key of Rodentia and Lagomorpha can be used for their behavioral ecology and dietary analysis of upper predators to serve as the basis for ecological research.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.5
• /
• pp.395-402
• /
• 2004

We need to develop technology of identifying high temperature high pressure(HTHP) synthetic diamond and HTHP treated natural diamonds from untreated natural diamonds to cope with sophisticated diamond enhancing technology. We had successfully identified synthetic diamonds using a vibrating sample magnetometer due to their ferromagnetic property. In addition, we identified the HTHP enhanced TypeIa, TypeIIa diamonds by employing non-destructive Fourier Transform Infrared(FTIR) spectroscopy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.5
• /
• pp.817-822
• /
• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is cheap, fast, and non-destructive. We proposed using a new method of micro-Raman spectroscopy for checking the local HPHT residual stress to distinguish these diamonds from natural ones. We observe unique ~10f compressive and tensile strains at Type I and Type II diamonds after HPHT treatment. Our result implies that our proposed methods may be appropriate fur identification of the treated diamonds with appropriate reference samples.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.10
• /
• pp.154-160
• /
• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2020.11a
• /
• pp.75-77
• /
• 2020

There was an outbreak of COVID-19 on the Diamond Princess cruise ship. Distinguishing close contacts is the important problem to be addressed. Close contacts mean people who stays with the patients of disease like COVID-19 over a period of time. The passenger position on board can be obtained by indoor positioning technology. The feature of close contacts is similar location with COVID-19 patients. Therefore, this paper proposed the idea of distinguishing close contacts on board based on DBSCAN algorithm.

• Journal of the Mineralogical Society of Korea
• /
• v.21 no.4
• /
• pp.435-442
• /
• 2008

Natural, synthetic, and treated diamonds were studied by NMR and EPR. It was demonstrated that natural and synthetic diamonds, treated and non-treated diamonds, high pressure high temperature (HPHT) treated and electron beam treated diamonds could be distinguished among each other based on the $^{13}C$ NMR spectra acquired for relatively short periods of 100 minutes. The $^{13}C$ NMR linewidths of gem quality synthetic diamonds were broader than 1.6 ppm due to the paramagentic effects of transition metals, generally used as catalysts, while the linewidths of gem quality natural diamonds were narrower than 0.5 ppm regardless of the methods of treatment. The linewidth (0.5 ppm) for a HPHT treated, gem quality natural diamond was as broad as more than twice of the linewidth (0.2 ppm) of an electron beam treated diamond. The $^{13}C$ NMR signal intensities of treated, gem quality natural diamonds were as strong as more than 10 times of the intensities of non-treated, gem quality natural diamonds. When correlated with the concentrations of the paramagnetic defects (electrons) obtained from the EPR spectra, the relative $^{13}C$ NMR signal intensities increased in proportion to the concentrations of the paramagnetic electrons contained in each sample but the electron beam treated diamond was an exception. This suggested that the lattice component, in addition to the paramagnetic defect component, should also be considered in determining the $^{13}C$ NMR signal intensity of the electron beam treated diamond.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.11
• /
• pp.3054-3059
• /
• 2009

Natural black diamonds of single crystal, polycrystalline, and agglomerated roughs become important for their industrial and gem stone application. We performed the conventional gemological tests of thermal diffusion, apparent density, scratch test, and magnification test as well as the advanced tests of Raman spectroscopy, X-ray diffraction test and Lang topography. We conclude that scratch test with SiC paper was the most efficient method in view point of speed and cost. Raman spectroscopy and XRD were useful for identification of diamond while Lang topography offered a good visualization method of the grain structure of polycrystalline black diamond roughs.

• Journal of the Korean Ceramic Society
• /
• v.33 no.9
• /
• pp.1045-1049
• /
• 1996

Pressureless-sintered polycrystalline alumina and carbon steel were joined with Ag-33.5Cu-1.5Ti (wt%) brazing alloy. SEM observation revealed that two reaction layers with different thicknesses were continuously formed between the alumina and the brazing alloy. A thick layer formed on the brazing alloy side was identified as Ti3(Cu0.93Al0.07)3O phase with diamond cubic structure. Another thin layer adjacent to the alumina was revealed as $\delta$-TiO phase of which the crystal structure was HCP with a lattice parameter of a0=0.419 nm and c0=0.284 nm. It was confirmed using XPS analysis that $\delta$-TiO was formed directly by a redox reaction of alumina with titanium ir, molten brazing alloy.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.14 no.1
• /
• pp.21-26
• /
• 2004

Results from PL and Raman spectroscopic analyses of HPHT (high-pressure high-temperature) treated type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar color and type. We identify a number of significant changes by 325 nm He/Cd laser excitation. Several peaks are removed completely, including H4, H3 system in HPHT treated diamond. The N3 system, however, increased in emission. Also we can find the behaviour of the nitrogen-vacancy related center N-V centers at 575 and 637.1 nm, as observed with 514 nm Ar ion laser excitation. When these centers are present, the FWHM (full width at half maximum) of 637.1 nm luminescence intensities offers a potential means of separating HPHT-treated from untreated type IIa diamonds. The width of 637.1 nm $(N-V)^-$line measured at the position oi half the peak's height are determine to range from 19.8 to $32.1cm^{-1}$ for HPHT treated diamonds.