• 대한의생명과학회지
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• 제18권1호
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• pp.42-48
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• 2012

This study was performed to investigate the urinary methyl hippuric acid (UMHA) excretion among aircraft maintenance workers exposed to xylene by examination of blood test, urine test and biochemical tests. Study subjects (301) were divided into 2 groups; non-exposed group (n=123, who were not exposed to xylene), and exposed group (n=178, who were exposed to xylene). The average of blood level and MHA level was normal. The ${\gamma}$-GTP level was 35.5 IU/L (45.7%) in the exposed group and 27.9 IU/L (44.7%) in the non-exposed (control) group. The proportion of total cholesterol (TG) level higher than 150 mg/dl were 34.3% in the exposed group and 21.1% in the non-exposed group. These results were showed statistically significant difference (${\chi}^2$ = 6.10, P<0.05). Other items showed no statistically significant differences. The results of urine tests were no statistically significant differences in protein, occult blood and glucose level.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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• pp.293-299
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• 2004

In this paper, thermal and mechanical properties of electric epoxy with water aging were discussed. We made elastic epoxy specimen adding a ratio of 0〔phr〕20〔phr〕, 35〔phr〕 and 53〔phr〕 with modifier to existing epoxy. We studied mechanical property of elastic resin after absorption in water from 0 to 484 hours. As a result, diffusion factor of elastic epoxy showed 20-21${\times}$10$^{-4}$ $\textrm{mm}^2$/s and general epoxy showed 9.5${\times}$10$^{-4}$ $\textrm{mm}^2$/s. Elastic property increased linearly according to addiction and decreased according to water absorption. Tensile strength was reduced according to addition. It was affected by water absorption of micro-void of elastic epoxy. Hardness inclined to decrease after increasing according to absorbed time. In water-absorption state, it was experimented a change of heat flow by temperature of elastic epoxy and change of thermal expansion coefficient. DSC (Differential Scanning Calorimetry) and TMA (Thermomechanical Analysis) equipments were used to measure Tg. A temperature ringe of DSC was from -0($^{\circ}C$) to 200($^{\circ}C$). One of TMA was from -0($^{\circ}C$) to 350($^{\circ}C$). In addition, we investigated structural analysis of water absorbed specimen using SEM (Scanning Electron Microscope).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 춘계학술대회 논문집
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• pp.30-33
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• 1992

This thesis was investigated on ion-induced characteristics in a-$Se_{75}Ge_{25}$ positive and negative resists for focused-ion-beam microlithogaphy. The exposed a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to~$10_{16}$ dose of Ga+. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons(~$10^{21}$photons/cm2). This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~$220^{\circ}C$). When focused ion beams are used for direct exposure of resist over a substrate, unwanted implantation of the substrate may be an issue. A possible way to avoid this is to match the thickness of the resist to the range of ions in the resist. Thin aspect is currently under investigation.

• 한국재료학회지
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• 제21권5호
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• pp.283-287
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• 2011

As the performance of microelectronic devices is improved, the use of copper as a heat dissipation member is increasing due to its good thermal conductivity. The high thermal conductivity of copper, however, leads to difficulties in the joining process. Satisfactory bonding with copper is known to be difficult, especially if high shear and peel strengths are desired. The primary reason is that a copper oxide layer develops rapidly and is weakly attached to the base metal under typical conditions. Thus, when a clean copper substrate is bonded, the initial strength of the joint is high, but upon environmental exposure, an oxide layer may develop, which will reduce the durability of the joint. In this study, an epoxy adhesive formulation was investigated to improve the strength and reliability of a copper to copper joint. Epoxy hardeners such as anhydride, dihydrazide, and dicyandiamide and catalysts such as triphenylphosphine and imidazole were added to an epoxy resin mixture of DGEBA and DGEBF. Differential scanning calorimetry (DSC) analyses revealed that the curing temperatures were dependent on the type of hardener rather than on the catalyst, and higher heat of curing resulted in a higher Tg. The reliability of the copper joint against a high temperature and high humidity environment was found to be the lowest in the case of dihydrazide addition. This is attributed to its high water permeability, which led to the formation of a weak boundary layer of copper oxide. It was also found that dicyandiamide provided the highest initial joint strength and reliability while anhydride yielded intermediate performance between dicyandiamide and dihydrazide.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제21권2호
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• pp.134-140
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• 2018

Chylomicron retention disease, also known as Anderson's disease, is a rare hereditary hypocholesterolemic disorder, recessive inherited, characterized by nonspecific symptoms as abdominal distension, steatorrhea, and vomiting associated with failure to thrive. We describe a patient with failure to thrive, chronic diarrhea and steatorrhea who the diagnosis of chylomicron retention disease was established after several months of disease progression. The genetic study confirmed a homozygosity mutation in SAR1B gene, identifying a mutation never previous described [c.83_84delTG(p.Leu28Argfs*7)]. With this case report the authors aim to highlight for this very rare cause of failure to thrive and for the importance of an attempting diagnosis, in order to start adequate management with low fat diet supplemented with fat-soluble vitamins, reverting the state of malnutrition and avoiding possible irreversible and desvantating complications.

• The Korean Journal of Physiology and Pharmacology
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• 제21권3호
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• pp.279-286
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• 2017

The root bark extract of Aralia taibaiensis is used traditionally for the treatment of diabetes mellitus in China. The total saponin extracted from Aralia Taibaiensis (sAT) has effective combined antihyperglycemic and hypolipidemic activities in experimental type 2 diabetic rats. However, the active compounds have not yet been fully investigated. In the present study, we examined effects of twelve triterpenoid saponins on AMP-activated protein kinase (AMPK) activation, and found that compound 28-O-${\beta}$-D-glucopyranosyl ester (AT12) significantly increased phosphorylation of AMPK and Acetyl-CoA carboxylase (ACC). AT12 effectively decreased blood glucose, triglyceride (TG), free fatty acid (FFA) and low density lipoprotein-cholesterol (LDL-C) levels in the rat model of type 2 diabetes mellitus (T2DM). The mechanism by which AT12 activated AMPK was subsequently investigated. Intracellular ATP level and oxygen consumption were significantly reduced by AT12 treatment. The findings suggested AT12 was a novel AMPK activator, and could be useful for the treatment of metabolic diseases.

• 한국재료학회지
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• 제21권1호
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• pp.67-71
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• 2011

La doped CuO-ZnO-$Al_2O_3$ powders are prepared by sol-gel method with aluminum isopropoxide and primary distilled water as precursor and solvent. In this synthesized process, the obtained metal oxides caused the precursor such as copper (II) nitrate hydrate and zinc (II) nitrate hexahydrate were added. To improve the surface areas of La doped CuO-ZnO-$Al_2O_3$ powder, sorbitan (z)-mono-9-octadecenoate (Span 80) was added. The synthesized powder was calcined at various temperatures. The dopant was found to affect the surface area and particle size of the mixed oxide, in conjunction with the calcined temperature. The structural analysis and textual properties of the synthesized powder were measured with an X-ray Diffractometer (XRD), a Field-Emission Scanning Electron Microscope (FE-SEM), Bruner-Emmett-Teller surface analysis (BET), Thermogravimetry-Differential Thermal analysis (TG/DTA), $^{27}Al$ solid state Nuclear Magnetic Resonance (NMR) and transform infrared microspectroscopy (FT-IR). An increase of surface area with Span 80 was observed on La doped CuO-ZnO-$Al_2O_3$ powders from $25m^2$/g to $41m^2$/g.

• 콘크리트학회논문집
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• 제21권4호
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• pp.441-447
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• 2009

황산염침식을 방지하기 위하여 포틀랜드시멘트 중의 황산염침식 저항성이 우수한 시멘트를 선정하기 위한 연구의 일환으로 황산나트륨 용액에 360일간 침지한 후 모르타르의 역학적 특성 및 기기분석을 통하여 침식 특성을 평 가한 결과, 외관조사, 강도감소 및 길이변화에 따른 성능저하 순서는 보통 포틀랜드시멘트 >내황산염 포틀랜드시멘트 > 저열 포틀랜드시멘트 순으로 나타났다. 포틀랜드시멘트의 주요 반응생성물은 Calcite 피크 이외에도 황산염과의 반응으 로 인한 Gypsum, 에트린자이트 및 Thaumasite로 확인되었다. 포틀랜드시멘트의 경우 시멘트의 조성광물 비에 따라 성 능저하 형태가 상이하게 나타났다. 특히, C3A량과 칼슘실리케이트비가 가장 적은 저열 포틀랜드시멘트가 황산염침식 저 항성에 매우 우수한 것으로 확인되었다.

• Parasites, Hosts and Diseases
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• 제55권3호
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• pp.239-246
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• 2017

Strains of Toxoplasma gondii in Brazil are highly genetically diverse compared to strains from North America and Europe. Dogs are epidemiologically important because they act as sentinels for T. gondii infections in humans and are good indicators of environmental contamination. The aim of this study was to isolate and genetically characterize T. gondii strains from tissues of naturally infected Brazilian dogs. For this study, 21 blood samples were collected from dogs at the Zoonosis Control Centers of $Ilh{\acute{e}}us$ and Itabuna cities, Bahia, Brazil. The sera were examined for T. gondii antibodies using the indirect hemagglutination test. Brains and hearts of seropositive dogs were bioassayed in mice to isolate and characterize T. gondii parasites by PCR-RFLP using 10 genetic markers (SAG1, newSAG2, SAG3, BTUB, c22-8, c29-2, GRA6, PK1, APICO, and L358). However, T. gondii was isolated from only 4 (57.1%) dogs, designated TgDgBr6, 13, 17, and 21. All strains were virulent, causing clinical changes (rough hair coat, lethargy, and abdominal distention) and the death of all mice within 8-20 days after inoculation. Genetic analysis of these 4 T. gondii isolates revealed 4 distinct genotypes with different clonal lineage combinations (types I, II, and III) and 2 atypical alleles. Using PCR-RFLP with several markers, this study contributes to evaluations of the genetic diversity of strains circulating in Brazil.

• 한국재료학회지
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• 제21권8호
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• pp.444-449
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• 2011

Nano-sized $Y_2O_3$ powders were prepared via a sol-gel method starting with $Y(NO_3)_3{\cdot}6H_2O$ (Yttrium(III) nitrate hexahydrate) and water with ethanol as a cosolvent. $Y_2O_3$ is an important rare earth oxide and has been considered for use in nuclear applications, such as ceramic materials, due to its excellent optical and refractory characteristics. It has been used as a chemically stable substrate, a crucible material for melting reactive metals, and a nozzle material for jet casting molten rare earth-iron magnetic alloys. Oxalic acid ($C_2H_2O_4$) has been adopted as a chelating agent in order to control the rate of hydrolysis and polycondensation, and ammonia was added in order to adjust the base condition. The synthesized $Y_2O_3$ powder was characterized using TG/DTA, XRD, FE-SEM, BET and Impedance Analyzer analyses. The powder changed its properties in accordance with the pH conditions of the catalyst. As the pH increases according to the FE-SEM, the grain grew and it showed that the pore size decreased while confirming the effect of the grain size. The nano-material $Y_2O_3$ powders demonstrated that the surface area was improved with the addition of oxalic acid with ammonium hydroxide.