• Journal of Environmental Science International
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• v.19 no.12
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• pp.1447-1454
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• 2010

In this study, the detection limits of lower fatty acids in air were investigated by using Dynamic SPME(Solid Phase Micro-Extraction), i.e. improved Head Space - SPME method(HS-SPME). This Dynamic SPME, called SPDE(Solid Phase Dynamic Extraction), is the analytical method for volatile compounds in air with the extraction by using a stainless steel needle of which inner surface is coated with adsorption material and following the gas chromatographic analysis by inserting the needle into a injection port of GC and subsequently, desorption of the volatile compounds into a gas-chromatographic column. Extraction was carried out by passing the sample air through the needle with a suction pump which has been used for a detection tube. The result of measurement for the 6 lower fatty acids showed that the detection limits ranged from 0.10 ppm to 0.44 ppm and the linear correlation coefficients were over 0.99. Relative standard deviations obtained from 5 analytical repetition of a ca. 1.6 ppm standard mixture were in the range of 1.87%~2.47%. This method has been shown to be a adequate for the measuring C2~C5 fatty acids in air in the concentrations of over several hundreds ppb.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.462-463
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• 2007

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of composite insulation composed of epoxy resins with N2, air are studied in non-uniform field. The gap of needle to plane was 3mm, 5mm. The pressure of air, nitrogen was varied within the range of 0.1~0.6MPa. The thickness of a needle is 1mm and the curvature radius of the end of needle is 100um. The diameter of a plane made of the stainless steel is 50mm. As a result of the experiment, the breakdown voltage is increased about 3 times when epoxy resins is composited. The thickness of epoxy resins filled opposite to electrode concentrated electric field weakly influences on breakdown voltage.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1389-1390
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• 2007

SF6 gas used widely as insulating component is rising as the environment problem. Electrical breakdown characteristics of epoxy and dry-air composite insulation was investigated on thickness of epoxy and pressure of dry-air under non-uniform field. The gap of needle to plane was from 2mm to 5mm. The pressure of dry-air was varied within the range of $0.1{\sim}0.6$ MPa. The thickness of a needle was 1mm and the curvature radius of a needle end was 100um. The diameter of a plane made of the stainless steel was 50mm. As a result of the experiment, breakdown voltage was increased about 3 times when epoxy was used. The impact that the thickness of epoxy influences on breakdown voltage was poor. It needs suitable thickness computation because the insulating gap of the gas is short as epoxy thickness increases.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.2
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• pp.83-87
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• 2020

Foreign body (FB) ingestion is commonly seen in the ear nose and throat (ENT) field, with different presentations and sequelae. FBs can arrest in the upper aerodigestive tract or continue further down into either the airway tract to the bronchus or the digestive tract to the intestines. The pathway of an FB depends on the size and shape of the FB and how sharp its edges are. Since the 20th century, the use of disposable stainless-steel needles in the oral cavity has proven to be an effective and safe method for performing various intraoral procedures like dental infiltration or a root canal wash. Complications from their use are rare. Generally, dental needle breakages are caused by patients biting the needle, incorrect injection techniques, or inadequate preventative measures. The sudden movement of a patient during a procedure is one of the most common causes of breakage. Occasionally, needles are swallowed during dental procedures such as a root canal. Here, we report a case of a patient that swallowed a broken needle during a dental procedure. A few days later, the patient presented with neck pain, swelling, and a FB sensation. When the patient presented, she claimed that her symptoms had onset after consuming a meal containing duck meat. Initially, the patient was diagnosed as having ingested a duck bone. However, intraoperatively, the FB was discovered to be an injection needle that had migrated from the throat to the neck.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.111-119
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• 2014

Objectives This study aims to analyze a thermal distribution in biological living tissue during warm needling therapy by using a finite element method. The analysis provides an understanding of warm needling's efficacy and safety. Methods A model which consisted of four-layered tissue and stainless steel needle was adopted to analyze the thermal distribution in living tissue with a bioheat transfer analysis. The governing equation for the analysis was a Pennes' bioheat equation. A heat source characteristic of warm needling therapy was obtained by previous experimental measurements. The first analysis of the time-dependent temperature distribution was conducted through points on a boundary between the needle and the tissue. The second analysis was conducted to visualize the horizontal temperature distribution. Results When heat source's peak temperatures was above $500^{\circ}C$ and temperature rising rates were relatively slow, the peak temperature at skin surface exceeded a threshold of pain and tissue damage ($45^{\circ}C$), whereas when the peak temperature was around $400^{\circ}C$, the peak temperature at the skin surface was within a safe limit. In addition, the conduction of combustion energy from the moxa was limited to the skin layer around the needle. Conclusions The results suggest that the skin layer around the needle can be heated effectively by warm needling therapy, but it appears to have little effect at the deeper tissue. These findings enhance our understanding of the efficacy and the safety of the warm needling therapy.

• Journal of Power System Engineering
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• v.10 no.3
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• pp.51-57
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• 2006

The effect of grain size on corrosion resistance and high temperature oxidation behavior was studied in 22Cr-15Ni-5W super austenitic stainless steels for desulfurization equipment as a heat power station. In the high temperature oxidation test, oxidation rate was increased as the temperature increased from $600^{\circ}C\;to\;800^{\circ}C$. In vapor, oxidation rate was faster than that in air. Because the vapor was inhibited nucleation of $Cr_2O_3$ film. And the high temperature oxidation resistance at $600^{\circ}C{\sim}800^{\circ}C$ was excellent from all specimens and specimen of the smallest grain size was the most excellent. Because increasing of diffusion course through the grain-boundary was promoted nucleation and growth of $Cr_2O_3$ film. In the test temperature at $600^{\circ}C{\sim}800^{\circ}C$, Cr rich round particle oxide was formed in air, whereas Fe rich needle type oxide was developed in vapor.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.3
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• pp.221-230
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• 1999

The surface nitrogen permeation of Al alloyed 0.14%C-13%Cr stainless steels was investigated after heat treating at $1050^{\circ}C{\sim}1150^{\circ}C$ in the nitrogen gas atmosphere. The strong affinity between Al and nitrogen permeates the nitrogen through the interior of the steels. Two precipitates of round type and needle type are observed at the surface layer. These precipitates mainly consist of AlN containing plenty of aluminum. The surface layer of 0.53%Al alloyed specimen shows ferrite phase, while the surface layers of 1.65%Al and 2.27%Al alloyed specimens appear ${\gamma}$ plus ${\alpha}$ phases. The depth of nitrogen permeation depends upon the Al content and microstructure of the matrix. The 1.65%Al alloyed specimen representing ${\alpha}+{\gamma}$ matrix phases at the nitrogen permeation temperature shows the maximum case depth in this experiment. Although the surface hardness increases by raising the Al content of the specimen owing to the increase of nitride precipitation density, the nitride precipitation deteriorates the corrosion resistance in the solution of HCl, $H_2SO_4$, and $FeCl_3$.

• Journal of Food Hygiene and Safety
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• v.36 no.5
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• pp.430-439
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• 2021

Essential oils with excellent antibacterial activity were used to study the inhibitory effect against the six types of food poisoning biofilms formed on the surfaces of polyethylene (PE) and stainless steel (SS) that are widely used for food processing instruments and containers. The antibacterial activity of 20 kinds of essential oils was tested using the disk diffusion method. The result showed the degree of antibacterial activity in the following order: cinnamon> clove> lemongrass> peppermint> pine needle (highest to lowest). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cinnamon and clove oil were in the range of 0.63-1.25 mg/mL and 1.25-2.50 mg/mL, respectively. The MIC and MBC of lemongrass oil were 1.25-2.50 mg/mL and 2.50-5.00 mg/mL, respectively, showing slightly less antibacterial activity. Although the preventive effect of three types of essential oils on the biofilm formation differed slightly depending on food poisoning bacteria, PE, and SS, it was found that the precoating of 0.5% cinnamon, clove, and lemongrass oil on the PE and SS affects the formation of biofilm. Increased essential oil concentration significantly inhibited the biofilm formation for all food poisoning bacteria (P<0.05), and biofilms of Listeria monocytogenes and Staphylococcus aureus were not formed when treated with 0.5% cinnamon and clove oil. The elimination effect of food poisoning bacteria biofilms formed on the surfaces of PE and SS differed depending on the type of food poisoning bacteria. Still, the biofilm elimination effect increased as the essential oil concentration increased, and the biofilm elimination rate of clove oil was generally high. Therefore, this study found that the cinnamon and clove essential oils (0.5%) are suitable natural materials that effectively prevent, inhibit, and remove the biofilms formed by the food poisoning bacteria on the surfaces of polyethylene and stainless steel.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1451-1457
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• 2002

When an aqueous liquid such as water having high electric conductivity and high surface tension is discharged from a nozzle under a strong DC electric field, fine drops ranging from 30 to 450 microns can be obtained only through the spindle mode. In the present study, effects of the electric conductivity and the surface wettability of nozzle materials on formation of drops with this mode were investigated. For that, three nozzles with the same size but with different materials were prepared and tested; a stainless steel needle, and a plain and a metal (gold)-coated (except for the tip portion) silica needles. Uniform drops were obtained with the gold-coated silica nozzle over the wider range of the DC voltage input. That is, formation of the liquid cone and detachment of the liquid spindle (ligament) can be more stabilized and frequent with the needles having high electric conductivity but with low surface wettability at their tips.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.101-102
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• 2008

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of vacuum with air are studied in non-uniform field. The gap of needle to plane was 0.5mm. The pressure of vacuum the range of 10^-4${\sim}$10^-5torr. The diameter of a plane made of the stainless steel is 150mm. As a result of the experiment, the breakdown voltage is increased about degree of vacuum increased. The electrode material influenced breakdown voltage in vacuum.