• Journal of Acupuncture Research
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• v.22 no.6
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• pp.135-140
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• 2005

Objectives : There have been several studies about the quality of acupuncture needle tip recently. We have investigated the condition of the tip of the acupuncture needles in the last studies. In the former studies, we discovered the metallic scuff, lumps and irregularities of the acupuncture needle tips under the microscope. But, no information was available on those foreign materials' identity. Methods : We have selected 200 needles of 1000 pieces from several companies by randomized methods. And we observed the tip of the 6 needles selected finally at ${\times}1000\;or\;{\times}3000$ magnification and analyzed the components of the metallic scuff, lumps and irregularities of the needle tips with a SEM-EDX analyser. Results : We found that the identity of the metallic scuff, lumps and irregularities of the needle tips were metallic materials and silicon. For example, A point was composed of Fe(69.78%), Cr(17.71%), Ni(8.11%), Zn(2.04%), Si(1.23%), Mn(1.12%), and B point was composed of Si(66.40%), Fe(26.76%), Cr(6.84%). Conclusion : The results of this study confirm that there is a real possibility of the remaining of metallic materials and silicon in body of patient, after acupuncture treatment. Therefore, it is necessary to intensify our efforts to make needles of good quality and to concentrate on manufacturing process of acupuncture needles completely to be free from danger in acupuncture treatment.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1175-1182
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• 2014

In this study, we examined the effect of cathode from electrolysis reactor for treating ballast water. We are going to select a suitable cathode for seawater electrolysis after considering the effect on the generation of the oxidant of cathode and the electrode deposition materials adhering to the surface of cathode. Anode is Ru-Ti-Pd electrode and cathode are Ti, Pt, JP520 (Ni-Pt-Ce) electrodes. Using the cathode of the three types, experiments were conducted to examine the effects of TRO (total residual oxidants) generation concentration and RNO (N, N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation concentration (in 1, 35 psu), ohmic drop, FESEM(field emission scanning electron microscope) observation of cathode surface and EDX (energy dispersive X-ray spectroscopy) measurements of attached fouling material. The results showed that TRO generation concentration and RNO degradation concentration in according to each type of cathode are not different. The attached fouling materials were observed on the surface of Ti and the JP520 electrode by the observation of SEM after electrolysis for two hours, but it was not observed on the surface of Pt electrode. When considering the surface ohmic drop of cathode and the attached fouling materials, Pt electrode was judged as the excellent cathode.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.229-234
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• 2017

In this study, TiAl alloy was fabricated by a centrifugal casting method for turbo charge of automotive. Optimum conditions for defectless morphology using various ceramic mold were investigated. The crystal structure, microstructure, and chemical composition of the TiAl prepared by centrifugal casting were studied by X-ray diffractometer (XRD), optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS), microvickers hardness analyzer (HV). Two kinds of dendrite structures were observed with 4-fold and 6-fold symmetries. The FE-SEM, EDS and HV examinations of the as-cast TiAl showed that the thickness of the oxide layer (${\alpha}$-case) was typically less than $50{\mu}m$.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.219-248
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• 1989

The purposes of this study were to analyze the microstructural and compositional changes of metal surfaces following different conditions of preoxidizing heat treatment, to investigate the composition of metal oxides, and to evaluate the effect of preoxidation and removal of surface oxides on microstructure and diffusion profiles. The techniques of EDAX (energy-dispersive analysis of x-ray), ESCA (electron spectroscopy for chemical analysis), and EPMA (electron probe micro analysis) were used, along with SEM (scanning electron microscopy). The obtained results were as follows : 1. A surface of the specimen became rough and the amount of the metal oxides increased with increasing the heat treatment time and temperature and the partial pressure of oxygen. 2. At an air pressure of 28' vacuum, the higher the temperature and the longer the time of preoxidation, the higher Ni concentration was detected. 3. Cr concentration in the specimen heat treated with air was higher than that of with vacuum. 4. The oxides in the specimens were mainly composed of Ni and Cr oxides. On the globular growth particles, significant rises in Al concentration of Rexillium III and Ti concentration of Verabond were noted. 5. Atomic diffusion occurred at the ceramic-metal interface, furthermore the amount of the flux was increased with preoxidation heat treatment.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.3.1-3.10
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• 2020

Objectives: This study investigated the indirect effect of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA), as 2 calcium silicate-based hydraulic cements, on human dental pulp stem cells (hDPSCs) through different dentin thicknesses. Materials and Methods: Two-chamber setups were designed to simulate indirect pulp capping (IPC). Human molars were sectioned to obtain 0.1-, 0.3-, and 0.5-mm-thick dentin discs, which were placed between the 2 chambers to simulate an IPC procedure. Then, MTA and CEM were applied on one side of the discs, while hDPSCs were cultured on the other side. After 2 weeks of incubation, the cells were removed, and cell proliferation, morphology, and attachment to the discs were evaluated under scanning electron microscopy (SEM). Energy-dispersive X-ray (EDXA) spectroscopy was performed for elemental analysis. Alkaline phosphatase (ALP) activity was assessed quantitatively. The data were analyzed using the Kruskal-Wallis and Mann-Whitney tests. Results: SEM micrographs revealed elongated cells, collagen fibers, and calcified nucleations in all samples. EDXA verified that the calcified nucleations consisted of calcium phosphate. The largest calcifications were seen in the 0.1-mm-thick dentin subgroups. There was no significant difference in ALP activity across the CEM subgroups; however, ALP activity was significantly lower in the 0.1-mm-thick dentin subgroup than in the other MTA subgroups (p < 0.05). Conclusions: The employed capping biomaterials exerted biological activity on hDPSCs, as shown by cell proliferation, morphology, and attachment and calcific precipitations, through 0.1- to 0.5-mm-thick layers of dentin. In IPC, the bioactivity of these endodontic biomaterials is probably beneficial.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.2003-2005
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• 2002

바이오 마이크로 시스템 및 바이오 MEMS 분야, 특히 실리콘을 기질로 하는 바이오 센서 제작에서 반도체 공정 기술은 센서의 대량 생산과 초소형화를 위해서 반드시 필요한 기술이다. 그러나, 감지전극의 마이크로화에 따른 센서의 감도 및 안정성 저하 문제는 해결해야 할 과제이다. 최근, 다공질 실리콘이 갖는 대면적이 실리콘 기질과 생체 고분자 (예: 단백질, 핵산 등) 간의 결합력을 향상시킬 수 있음이 알려지면서, 바이오 센서 분야에서, 새로운 형태의 드랜스듀서 재료로서의 다공질 실리콘에 대한 논의가 활발히 전개되고 있으며 또한, ISFET (Ion-Selective Field-Effect Transistors) 와는 달리 다공질 실리콘 층은 저항이 크기 때문에 센서 제작 과정에서의 부가적인 절연막을 필요로 하지 않는다. 본 연구에서는, 백금을 증착한 다공질 실리콘 표면에 전도성 고분자로서 Polypyrrole (PPy) 필름과 생체 고분자 물질로서 Urease를 각각 전기화학적으로 흡착하였다. 다공질 실리콘 층의 형성을 위해 테플론 소재의 전기화학 전지에 불산 (49%), 에탄올 (95%), $H_2O$ 혼합 용액을 넣고 실리콘 웨이퍼에 일정시간 수 mA의 산화 전류를 흘려주었으며, 약 $200{\AA}$의 티타늄 박막과 $200{\AA}$의 백금 박막을 RF 스퍼터링하여 작업 전극을 제작하였고, 백금 박막 및 Ag를 기화 증착하여 제작한 Ag/AgCl 박막을 각각 상대 전극과 기준전극으로 하였다. 박막 전극의 표면 분석을 위해 SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-ray spectroscopy) 등을 이용하였다. 제작된 요소 센서로부터 요소 농도 범위 0.01 mmol/L ${\sim}$ 100 mmol/L에서 약 0.2 mA/decade의 감도를 얻었다.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.147-155
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• 2008

The dental orthodontic wire provides a good combination of strength, corrosion resistance and moderate cost. The purpose of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance and physical property of orthodontic wire using various instruments. Wires(round type and rectangular type) were used, respectively, for experiment. Ion plating was carried out for wire using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive X-ray spectroscopy(EDS), atomic force microscopy(AFM), vickers hardness tester, and electrochemical tester. The surface of TiN and ZrN coated wire was more smooth than that of other kinds of non-coated wire. TiN and ZrN coated surface showed higher hardness than that of non-coated surface. The corrosion potential of the TiN coated wire was comparatively high. The current density of TiN coated wire was smaller than that of non-coated wire in 0.9% NaCl solution. Pit nucleated at scratch of wire. The pitting corrosion resistance $|E_{pit}-E_{rep}|$ increased in the order of ZrN coated(300 mV), TiN coated(120 mV) and non-coated wire(0 mV).

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.306-315
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• 1996

This study was performed to develop the biological treatment technology of wastewater polluted with heavy metals. The lead-tolerant microorganism, Pseudomonas aeruginosa which possessed the ability to accumulate lead, was isolated from the industrial wastewater polluted with various heavy metals. The characteristics of lead accumulation in the cells and the recovery of the lead there from were investigated. Removal rate of lead from the solution containing 100mg/l of lead by the lead-tolerant microorganism was more than 97% at 48 hours after inoculation with the microorganism. A large number of the electron-dense granules were found mainly on the cell wall and cell membrane fractions, when determined by transmission electron microscopy. Energy dispersive X-ray spectroscopy revealed that the electron-dense granules were lead complex with the substances binding heavy metals. The lead accumulated into cells was not desorbed by distilled water, but more than 87% of the lead accumulated was desorbed by 0.1M-EDTA. The residues of the cells after combustion at $550^{\circ}C$ amounted to about 30% of the dry weight of the cells. EDS analysis showed that the residues were relatively pure lead compounds containing more than 86% of lead.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.215-220
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• 2016

A new immobilization technique of nanoscale $TiO_2$ powder to expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of $TiO_2$ powder-embedded EPS balls were evaluated using methylene blue (MB) solution under ultraviolet irradiation (${\lambda}=254nm$). Based on the scanning electron microscope (SEM) images and associated energy-dispersive X-ray spectroscopy (EDX) analysis, the components of the intact EPS balls were mainly carbon and oxygen, whereas those of $TiO_2$-immobilized EPS balls were carbon, oxygen, and titanium, indicating that relatively homogenous patches of $TiO_2$ and glycerin film were coated on the surface of EPS balls. Based on the comparison of degradation efficiencies of MB between intact and $TiO_2$-immobilized EPS balls under UVC illumination, the degradation efficiencies of MB can be significantly improved using $TiO_2$-immobilized EPS balls, and surface reactions in heterogeneous photocatalysis were more dominant than photo-induced radical reactions in aqueous solutions. Thus, $TiO_2$-immobilized EPS balls were found to be an effective photocatalyst for photodegradation of organic compounds in aqueous solutions without further processes (i.e., separation, recycling, and regeneration of $TiO_2$ powder). Further study is in progress to evaluate the feasibility for usage of buoyant $TiO_2$-immobilized EPS to inhibit the excessive growth of algae in rivers and lakes.

• Tribology and Lubricants
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• v.30 no.2
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• pp.108-115
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• 2014

The friction behaviors of bulk amorphous thermal spray coating (BAC) and second phase-reinforced composite coatings using a high velocity oxy-fuel spraying process were investigated using a ball-on-disk test rig that slides against a ceramic ball in an atmospheric environment. The surface temperatures were measured using an infrared thermometer installed 50 mm from the contact surface. The crystallinities of the coating layers were determined using X-ray diffraction. The morphologies of the coating layers and worn surfaces were observed using a scanning electron microscope and energy-dispersive spectroscopy. The results show that the friction behavior of the monolithic amorphous coating was sensitive to the testing conditions. Under lower than normal loads, a low and stable friction coefficient of about 0.1 was observed, whereas under a higher relative load, a high and unstable friction coefficient of greater than 0.3 was obtained with an instant temperature increase. For the composite coatings, a sudden increase in friction coefficient did not occur, i.e., the transition region did not exist and during the friction test, a gradual increase occurred only after a significant delay. The BAC morphology observations indicate that viscous plastic flow was generated with low loads, but severe surface damage (i.e., tearing) occurred at high loads. For composite coatings, a relatively smooth surface was observed on the worn surface for all applied loads.