• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.55-61
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• 2009

Passive fitting of meso-structure and super-structures is a predominant requirement for the longevity and clinical success of osseointegrated dental implants. However, precision and passive fitting has been unpredictable with conventional methods of casting as well as for corrective techniques. Alternative to conventional techniques, electro discharge machining(EDM) is an advanced method introduced to dental technology to improve the passive fitting of implant prosthesis. In this technique material is removed by melting and vaporization in electric sparks. Regarding the efficacy of EDM, the application of this technique induces severe surface morphological and elemental alterations due to the high temperatures developed during machining, which vary between $10,000{\sim}20,000^{\circ}C$. The aim of this study was to investigate the morphological and elemental alterations induced by EDM process of casting dental gold alloy and non-precious alloy used for the production of implant-supported prosthesis. A conventional clinical dental casting alloys were used for experimental specimens patterns, which were divided in three groups, high fineness gold alloy(Au 75%, HG group), low fineness gold alloy(Au 55%, LG group) and nonprecious metal alloy(Ni-Cr, NP group). The UCLA type plastic abutment patterns were invested with conventional investment material and were cast in a centrifugal casting machine. Castings were sandblasted with $50{\mu}m\;Al_2O_3$. One casting specimen of each group was polished by conventional finishing(HGCON, LGCON, NPCON) and one specimen of each group was subjected to EDM in a system using Cu electrodes, kerosene as dielectric fluid in 10 min for gold alloy and 20 min for Ni-Cr alloy(HGEDM. LGEDM, NOEDM). The surface morphology of all specimens was studied under an energy dispersive X-ray spectrometer (EDS). The quantitative results from EDS analysis are presented on the HGEDM and LGEDM specimens a significant increase in C and Cu concentrations was found after EDM finishing. The different result was documented for C on the NPEDM with a significant uptake of O after EDM finishing, whereas Al, Si showed a significant decrease in their concentrations. EDS analysis showed a serious uptake of C and Cu after the EDM procedure in the alloys studied. The C uptake after the EDM process is a common finding and it is attributed to the decomposition of the dielectric fluid in the plasma column, probably due to the development of extremely high temperatures. The Cu uptake is readily explained from the decomposition of Cu electrodes, something which is also a common finding after the EDM procedure. However, all the aforementioned mechanisms require further research. The clinical implication of these findings is related with the biological and corrosion resistance of surfaces prepared by the EDM process.

• Analytical Science and Technology
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• v.11 no.2
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• pp.112-119
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• 1998

A Siemens SemiQuant (SSQ) 3000 program, a precalibrated 'standardless' analytical program handling up to 90 elements, was evaluated for the fast analysis of various types of reference materials using a wavelength dispersive X-ray spectrometer. Various types of standard reference materials such as metal discs, metal chips, and geological materials in powder form were analysed and it took 23 minutes of measuring time for 75 elements. Measurements of geological reference materials using different sampling methods were carried out and their data were interactively evaluated. The analysis of materials of a known matrix concentration such as stainless steels provided higher precision value compared to totally unknown samples. The analyses of materials prepared as pressed pellets or fused glass beads provided higher precision values compared to the measurement of loose powders with a foil on the sample surface and helium operation, though their sampling procedures were more complicate and took more time. Since very light elements such as boron, carbon, and oxygen have a strong influence on the matrix effects and also on the calculation of effective matrix corrections, the rhodium Compton check was applied to verify the reliability of the defined light element concentrations of light matrix materials and the defined major sample compounds. Failure of defining correct matrix resulted in an unoptimized matrix correction and therefore in the wrong calculation of the element concentration.

• Journal of Conservation Science
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• v.22
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• pp.87-98
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• 2008

Microstructures and chemical compositions of 24 bronze mirrors recovered from the Korean peninsula were examined using the scanning electron microscope equipped with the energy dispersive spectrometer in an effort to characterize the treatments applied on their surface. Their provenance and chronology are mostly unspecified except for two objects from a Koryo burial site. In antiquity the surface of bronze mirrors was frequently finished by mere polishing when their tin content was high enough to guarantee the required reflectivity. In many cases, however, their surface was given a special treatment. The most typical treatment was to coat the surface with tin in two different processes referred to as wipe-tinning and amalgam-tinning. In wipe-tinning only tin was used, but in amalgam-tinning tin and mercury were used together. The surface was often coated with mercury in a process known as mercury-polishing. The present mirrors showed that all these techniques were in fact practiced, not only on the reflective surface but, in some cases, on the decorative surface. The detection of mercury played a crucial role in the assessment of a specific technique applied in each mirror. Mercury often remained in the substrate in the form of sulfide and thereby allowed the method of surface treatment to be estimated even when the coated layer was completely lost. The future study is expected to uncover the regional and temporal variation of the surface treatments to the better understanding of bronze mirrors with respect to provenance and chronology.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.5
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• pp.485-500
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• 2016

We examined acidity state of inorganic aerosol and oxidation state of organic aerosol by High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) at Baengnyeong Super site from Jan 2012 to Dec 2013. Additionally, we carried out the analysis for the aerosol component group of organic matter ($C_xH_y$, $C_xH_yO_1$, $C_xH_yO_z$, $C_xH_yO_zN_p$) and elemental composition to calculate H/C, O/C, N/C, OM/OC and identify the oxidation state. The aerosol chemical composition in this study is dominated by sulfate ($SO_4{^{2-}}$), nitrate ($NO_3{^-}$) plays a smaller role in aerosol acidity. Ammonium ($NH_4{^+}$) was found in a formation of $(NH_4)_3H(SO_4)_2$. However, the binding formations of $NH_4NO_3$ and $NH_4Cl$ increase in the winter. $C_xH_yO_1$ indicating the oxidized state of $PM_{1.0}$ has the highest ratio of 41% while $C_xH_y$ indicating the non-oxidized state has a lower ratio of 36%, meaning that the oxidation level of $PM_{1.0}$ in Baengnyeong Island is high. The ratio between H/C and O/C was 1.33 and 0.78 respectively, showing the characteristic of LV-OOA (Low volatility-Oxygenated Organic Aerosol). Acidic and oxidized aerosols sampled during this field study were largely anthropogenic in origin from Chinese continent and photochemically aged.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.542-547
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• 2017

This paper was to analyze the membrane characterization of hydrophilicity, surface morphology and membrane chemical anlysis of three commercial microfiltration/ultrafiltration membranes, and evaluate the filtration performance of a seawater to assess the availability for pretreatment of desalination process. From the results of contact angle, Mem-3, fabricated with polyacrylonitrile, was highly hydrophilic. It find out that Mem-3 has more anti-biofouling property. In Field emission scanning electron microscope (FESEM), Mem-1 (polyethylene) and Mem-2 (Polyvinylidenefluoride) showed the sponge-like shape and Mem-3 showed finger-like shape. Membrane chemical analysis by energy dispersive spectrometer (EDS) presented that Mem-2 was mostly fluoride and Mem-3 had s high ratio of N (32.47%) due to the nitrile group. The permeation flowrate per time on suction pressures using deionized water (D.I. water) tends that permeation rate of Mem-3 more increased when the pressure was increased compared to other membranes. From the results of turbidity and total suspended solids (TSS) removal, turbidity of permeate was 0.191 NTU to 0.406 NTU and TSS was 2.2 mg/L to 3.0 mg/L in all membranes, indicating that it was not suitable for the pretreatment of seawater desalination by short-term experiments.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.3
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• pp.157-162
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• 2006

Objective of this research was to evaluate optimal conditions of arsenic adsorption in water by zero-valent iron (ZVI). Batch experiment showed that adsorption of arsenic by ZVI followed a Langmuir isotherm model. The masses of As(V) adsorbed onto ZVI were increased as decreasing pH of the reacting solution (pH 3: 2.05, pH 5: 1.82, pH 7: 1.24, pH 9: 1.03 mg As/g $Fe^0$) and as increasing the temperature ($15^{\circ}C$ : 1.59, $25^{\circ}C$ : 1.81, 35 : $1.93^{\circ}C$ mg As/g $Fe^0$). The SEM and EDS (energy dispersive X-ray spectrometer) analysis of morphology and structure of ZVI before and after reacting with arsenic in water revealed that a relatively smooth and large surface of ZVI was transformed into a coarse and small surface particle after the reaction. The EDS spectra on the chemical composition of ZVI demonstrated that arsenic was incorporated into ZVI by adsorption mechanism. The XRD analysis also identified that the only peak for $Fe^0$ in the ZVI before the reaction and confirmed that $Fe^0$ was transformed into $Fe_2O_3$ and FeOOH, and As into $FeAsO_4{\cdot}2H_2O$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1284-1288
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• 2009

Identification of various inorganic compound crystals contained in solar salts, which are produced from 12 areas of Jeonnam, was firstly made by the X-ray diffraction (XRD) technique. The analysis of the XRD spectra was carried out on the basis of Joint Committee on Powder Diffraction Standards (JCPDS) data and the results of Energy Dispersive X-ray Spectrometer (EDX) measurements. In particular, the analysis of the XRD spectra supported that each solar salt contains $Na_2S$ (Shinan Jeungdo and Sinui), $KMgCl_3$ (Shinan Bigeum), $Ca(ClO_3)_2$ (Shinan Docho), $CaAl_4O_7$ (Haenam Songji), $CaSiO_3$ and $CaCl_2$ (Goheung) as inorganic compound crystals, which have not been reported for the solar salts. Also, the XRD results indicated that the solar salts maintain a cubic NaCl crystal structure without any change of lattice parameters etc. However, it was shown in the Field Emission Scanning Electron Microscope (FE-SEM) images that an external form of the solar salts has a lamination layer shape of a cubic structure, which is different from a simple cubic form for the purified salts and the reagent NaCl.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.34.1-34.14
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• 2015

Background: Over the past 30-40 years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8 years. Methods: Mandibular reconstruction (8-10 years ago) was performed with pure (99.99 %) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Results: Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants. Conclusions: The surface morphology and the structure were not changed after 8 years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.109-110
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• 2014

주사전자현미경(Scanning Electron Microscopy: SEM)은 고체상태에서 미세조직과 형상을 관찰하는 데에 가장 다양하게 쓰이는 분석기기로서 최근에 판매되고 있는 고분해능 SEM은 수 나노미터의 분해능을 가지고 있다. 그리고 SEM의 초점심도가 크기 때문에 3차원적인 영상의 관찰이 용이해서 곡면 혹은 울퉁불퉁한 표면의 영상을 육안으로 관찰하는 것처럼 보여준다. 활용도도 매우 다양해서 금속파면, 광물과 화석, 반도체 소자와 회로망의 품질검사, 고분자 및 유기물, 생체시료 nnnnnnnnn와 유가공 제품 등 모든 산업영역에 걸쳐 있다(Fig. 1). 입사된 전자빔이 시료의 원자와 탄성, 비탄성 충돌을 할 때 2차 전자(secondary electron)외에 후방산란전자(back scattered electron), X선, 음극형광 등이 발생하게 되는 이것을 통하여 topography (시료의 표면 형상), morphology(시료의 구성입자의 형상), composition(시료의 구성원소), crystallography (시료의 원자배열상태)등의 정보를 얻을 수 있다. SEM은 2차 전자를 이용하여 시료의 표면형상을 측정하고 그 외에는 SEM을 플랫폼으로 하여 EDS (Energy Dispersive X-ray Spectroscopy), WDS (Wave Dispersive X-ray Spectroscope), EPMA (Electron Probe X-ray Micro Analyzer), FIB (Focus Ion Beam), EBIC (Electron Beam Induced Current), EBSD (Electron Backscatter Diffraction), PBMS (Particle Beam Mass Spectrometer) 등의 많은 분석장치들이 SEM에 부가적으로 장착되어 다양한 시료의 측정이 이루어진다. 이 중 결정구조, 조성분석을 쉽고 효과적으로 할 수 있게 하는 X선 분석장치인 EDS를 SEM에 일체화시킨 장비와 EDS 및 PBMS를 SEM에 장착하여 반도체 공정 중 발생하는 나노입자의 형상, 성분, 크기분포를 측정하는 PCDS(Particle Characteristic Diagnosis System)에 대해 소개하고자 한다. - EDS와 통합된 SEM 시스템 기본적으로 SEM과 EDS는 상호보완적인 기능을 통하여 매우 밀접하게 사용되고 있으나 제조사와 기술적 근간의 차이로 인해 전혀 다른 방식으로 운영되고 있다. 일반적으로 SEM과 EDS는 별개의 시스템으로 스캔회로와 이미지 프로세싱 회로가 개별적으로 구현되어 있지만 로렌츠힘에 의해 발생하는 전자빔의 왜곡을 보정을 위해 EDS 시스템은 SEM 시스템과 연동되어 운영될 수 밖에 없다. 따라서, 각각의 시스템에서는 필요하지만 전체 시스템에서 보면 중복된 기능을 가지는 전자회로들이 존재하게 되고 이로 인해 SEM과 EDS에서 보는 시료의 이미지의 차이로 인한 측정오차가 발생한다(Fig. 2). EDS와 통합된 SEM 시스템은 중복된 기능인 스캔을 담당하는 scanning generation circuit과 이미지 프로세싱을 담당하는 FPGA circuit 및 응용프로그램을 SEM의 회로와 프로그램을 사용하게 함으로 SEM과 EDS가 보는 시료의 이미지가 정확히 일치함으로 이미지 캘리브레이션이 필요없고 측정오차가 제거된 EDS 측정이 가능하다. - PCDS 공정 중 발생하는 입자는 반도체 생산 수율에 가장 큰 영향을 끼치는 원인으로 파악되고 있으며, 생산수율을 저하시키는 원인 중 70% 가량이 이와 관련된 것으로 알려져 있다. 현재 반도체 공정 중이나 반도체 공정 장비에서 발생하는 입자는 제어가 되고 있지 않은 실정이며 대부분의 반도체 공정은 저압환경에서 이루어지기에 이 때 발생하는 입자를 제어하기 위해서는 저압환경에서 측정할 수 있는 측정시스템이 필요하다. 최근 국내에서는 CVD (Chemical Vapor Deposition) 시스템 내 파이프내벽에서의 오염입자 침착은 심각한 문제점으로 인식되고 있다(Fig. 3). PCDS (Particle Characteristic Diagnosis System)는 오염입자의 형상을 측정할 수 있는 SEM, 오염입자의 성분을 측정할 수 있는 EDS, 저압환경에서 기체에 포함된 입자를 빔 형태로 집속, 가속, 포화상태에 이르게 대전시켜 오염입자의 크기분포를 측정할 수 있는 PBMS가 일체화 되어 반도체 공정 중 발생하는 나노입자 대해 실시간으로 대처와 조치가 가능하게 한다.

• Journal of Powder Materials
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• v.24 no.6
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• pp.437-443
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• 2017

SiC-based composite materials with light weight, high durability, and high-temperature stability have been actively studied for use in aerospace and defense applications. Moreover, environmental barrier coating (EBC) technologies using oxide-based ceramic materials have been studied to prevent chemical deterioration at a high temperature of $1300^{\circ}C$ or higher. In this study, an ytterbium silicate material, which has recently been actively studied as an environmental barrier coating because of its high-temperature chemical stability, is fabricated on a sintered SiC substrate. $Yb_2O_3$ and $SiO_2$ are used as the raw starting materials to form ytterbium disilicate ($Yb_2Si_2O_7$). Suspension plasma spraying is applied as the coating method. The effect of the mixing method on the particle size and distribution, which affect the coating formation behavior, is investigated using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) analysis. It is found that the originally designed compounds are not effectively formed because of the refinement and vaporization of the raw material particles, i.e., $SiO_2$, and the formation of a porous coating structure. By changing the coating parameters such as the deposition distance, it is found that a denser coating structure can be formed at a closer deposition distance.