• Journal of Korean Vacuum Science & Technology
• /
• 제4권4호
• /
• pp.102-106
• /
• 2000

We report scanning force microscope (SFM) observations of enhanced calcite dissolution in aqueous solution due to mechanical stimulation induced by the SFM tip. Images and mechanical treatment were performed in saturated ($\geq$ 60 ${\mu}{\textrm}{m}$) CaCO$_3$ solution adjusted to pH~9. Small area scans of monolayer steps significantly increased the step velocity in the scanned area (in the direction corresponding to dissolution) when the applied contact force is above about 160 nN fer the tips employed. The step velocity could be increased at least an order of magnitude by scanning at even higher contact forces (e.g.,270nN). This enhancement is a function of step orientation relative to the calcite lattice. Indentations near preexisting steps also locally enhance the step velocity. We present evidence that the higher dissolution rates are caused by stress-induced increases in the rate of double-kink nucleation.

• 한국레이저가공학회지
• /
• 제18권3호
• /
• pp.6-8
• /
• 2015

Finishing process includes deburring, polishing and edge radiusing. It improves the surface profile of specimen and eliminates the alien substance on surface. Deburring is the elimination process for debris of edges. Polishing lubricates surfaces by rubbing or chemical treatment. There are two types for electron finishing. The one is using pulse beam. The other is using the convergent and scanning electron beam. Pulse type device appropriates the large area process. But it does not control the beam dosage. Scanning type device has advantages for dosage control and edge deburring. We design the convergence and scan type. It has magnetic lenses for convergence and scan device for scanning beam. Magnetic lenses consist of convergent and objective lens. The lenses are designed by the specification(beam size and working distance). In this paper, we evaluate the convergence performance by pattern process. Also, we analysis the results and important factors for process. The important factors for process are beam size, pressure, stage speed and vacuum. These results will be utilized into systematizing pattern shape and the factors.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.967-968
• /
• 2007

This report is the study for laser scanning. Scanning control of $CO_2$ laser, He-Ne laser, used for the treatment of body skin, has relatively low band about hundered Hz. It could be used as a substitiute for expensive galvanometer that is the established scan method, which operates the number of KHz movement by using step motor when it operates low speed. To increase the accuracy of step motor's the angle of rotation, We could materialize 100Hz low band by using open loop, closed loop method with microprocessor. This causes it to be stable even direction by attaching electric capacity sensor. Therefore, We could expect to reduce the cost by manufacturing low band scanner rather than costly feedback galvanometer.

• 열처리공학회지
• /
• 제29권3호
• /
• pp.113-123
• /
• 2016

In the present work, we investigated the effects of the carbon potential on the formation of carbide at the carburized surface and anti-pitting fatigue strength in the supercarburized steels. Two low carbon steels with different Cr concentrations were adopted and the repeated supercarburizing treatment carried out with the different carbon potential conditions. The microstructure and carbides at the supercarburized surface were observed by using optical microscope and scanning electron microscope. The microhardness test was performed and the hardness distribution and the effective case depth at the supercarburized surface were discussed. The roller pitting fatigue test was carried out and the fatigue strength was evaluated with different the carbon potential conditions. The microstructure of the fatigue specimen surface was observed by means of scanning electron microscope and scanning transmission electron microscope. Depending on the chemical composition of the steels and the carbon potential condition, the resistance of temper softening and pitting failure was influenced due to the carbide distribution and the formation of coarse network carbide. Thus, it was confirmed that the control of the carbide formation is a key factor to improve the anti-pitting fatigue strength in the supercarburized steels.

• 대한두경부종양학회지
• /
• 제16권1호
• /
• pp.58-63
• /
• 2000

Objectives: To demonstrate effective diagnostic method and proper management of recurrent thyroid cancer through to compare treatment and surveillance of $I^{131}$ scanning detected recurrence and clinically detected recurrence. Material and Methods: We retrospectively analyzed clinical information about 46 patients who has recurrent thyroid cancer of 298 patients who have been primarily operated due to thyroid cancer in PMC at the over 10 years between 1986 and 1995. We examine incidence of recurrence due to pathologic types, site of recurrence, disease free interval, detection method of recurrence, and also treatment and progression of recurrence. A patients in which the clinical examination was entirely negative and the $I^{131}$ scan demonstrated either a new area of $I^{131}$ uptake or an increased area of concentration, compared to the previous scan, was designated as a recurrence detected by $I^{131}$ scan only. Recurrences that were obviously by physical examination or chest x-ray, etc were considered clinically detected recurrence, regardless of the the results of the thyroid scan. Results: Mean of disease tree interval(DFI) is 36months. When mean DFI of $I^{131}$ scan detected recurrence is 28months, whereas mean DFI of clinically detected recurrence is 47months. In statiscal analysis, p-value is 0.043 as significantly. In progression of recurrent patient, NED is 28case, AWD is Sease, DOD is 13case. Among the 13case, scan detected recurrence is lease of 20 patients(5%), whereas clinically detected recurrence is l2case of 26 patient(46%). In statiscal analysis, p-value is 0.003 as significantly. Conclusion: Early detection of the recurrent thyroid cancer by $I^{131}$ scanning leads to good progress compare with detection by clinical examination. NED: No Evidence of Disease AWD : Alive With Disease DOD : Dead Of Disease DOC: Dead of Other Cause

• 한국식품영양과학회지
• /
• 제22권5호
• /
• pp.596-602
• /
• 1993

신선찰벼와 한강찰벼 전분을 산처리하여 이호학적 성질, differential scanning calrorimetry 및 효소에 의한 가수분해율의 차이를 비교 검토하였다. 산 가수분해율은 한강찰벼가 약간 높았으며, 산처리에 따라 가용성 선형물질이 분해되어 ${\lambda}_{max}$와 청가는 감소하였고 또 물결합능력, 용해도 및 결정도는 증가하였으나 팽윤력은 감소하였다. 요오드 반응에 의한 최대흡수파장은 한강찰벼가 높았으나 최대흡수파장 및 680nm에서 흡광도는 시료간에 차이가 없었다. 물결합 능력과 용해도는 신선찰벼가 높았으나 팽윤력은 한강찰벼가 높았다. 가열에 의한 광투과도는 신선찰벼가 낮아서 열에 대한 안정성이 높았다. KSCN에 의한 겔부피는 신선찰벼가 커서 용출물질량이 많았다. 산처리중 전분의 결정형태는 A형이 유지되었으며 상대결정도는 신선찰벼가 높았다. DSC특성값은 산처리에 따라 감소하였으며, glucoamylase에 의한 가수분해율은 산처리에 따라 증가하여 산처리 48시간에 신선찰벼는 98%, 한강찰벼는 96%로 전체적으로 신선찰벼가 높았다.

• 열처리공학회지
• /
• 제9권3호
• /
• pp.177-186
• /
• 1996

Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN or TiC surface-alloyed layer with high hardness on the substrate by injecting reaction gas($N_2$ or $CH_4$). Laser surface alloying by means of process control is in many applications essential in order to obtain predictable hardening layer. This research has been investigated the effect of such parameters on TiN and TiC gas alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum surface hardness of TiN layer was obtained 1750Hv on the conditions of 0.8kW laser power, 0.8m/min scanning speed and 100% $N_2$ atmosphere. However, the maximum hardness of TiC formation layer after laser treatment was about 630Hv. As scanning speed was increased, the hardness and depth of these layers were decreased at constant laser power.

• 열처리공학회지
• /
• 제32권5호
• /
• pp.195-200
• /
• 2019

For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of $50{\sim}100{\mu}m$ through pre-heat treatment, cyclic heat treatment in ${\alpha}+{\gamma}$ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.

• Journal of the Korean Wood Science and Technology
• /
• 제15권3호
• /
• pp.24-33
• /
• 1987

This study was executed to investigate scanning electron microscopic characteristics of Korean Rhus lacquer coats. With the unrefined coat, distilled water, sodium hydroxide, acetic acid, ethyl alcohol, cold-check test, and accelerated weathering were performed after refining treatment. These treated lacquer coats were discussed through observation by scanning electron microscope and the obtained results were summarized as follows: 1. Compared with unrefined coat, the refined coat of Korean Rhus lacquer showed more even surface with regular distribution of dispression. 2. Korean Rhus lacquer coat heated at $120^{\circ}C$ for 3 hours revealed no observable difference irrespective of refining and unrefining. 3. Korean Rhus lacquer coat treated by distilled water, sodium hydroxide, acetic acid. ethyl alcohol, cold-check test. and ultraviolet radiation showed significant characteristics compared with untreated coat. Especially. large deformation and checkings were observed by cold-check test and ultraviolet radiation respectively. 4. The Korean Rhus lacquer coat radiated by ultraviolet ray showed 0.11 duller and 1.41 brighter than non-radiated coat through color difference calculator.

• The Journal of Advanced Prosthodontics
• /
• 제10권3호
• /
• pp.197-204
• /
• 2018

PURPOSE. To determine the extent of treatment traces, the roughness depth, and the quantity of titanium nitride (TiN) removed from the surface of CAD/CAM abutments after treatment with various instruments. MATERIALS AND METHODS. Twelve TiN coated CAD/CAM abutments were investigated for an in vitro study. In the test group (9), each abutment surface was subjected twice (150 g vs. 200 g pressure) to standardized treatment in a simulated prophylaxis measure with the following instruments: acrylic scaler, titanium curette, and ultrasonic scaler with steel tip. Three abutments were used as control group. Average surface roughness (Sa) and developed interfacial area ratio (Sdr) of treated and untreated surfaces were measured with a profilometer. The extent of treatment traces were analyzed by scanning electron microscopy. RESULTS. Manipulation with ultrasonic scalers resulted in a significant increase of average surface roughness (Sa, P<.05) and developed interfacial area ratio (Sdr, P<.018). Variable contact pressure did not yield any statistically significant difference on Sa-values for all instruments (P=.8). Ultrasonic treatment resulted in pronounced surface traces and partially detachment of the TiN coating. While titanium curettes caused predominantly moderate treatment traces, no traces or detectable substance removal has been determined after manipulation with acrylic curettes. CONCLUSION. Inappropriate instruments during regular plaque control may have an adverse effect on the integrity of the TiN coating of CAD/CAM abutments. To prevent defects and an increased surface roughness at the transmucosal zone of TiN abutments, only acrylic scaling instruments can be recommended for regular maintenance care.