• 한국철도학회논문집
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• 제13권4호
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• pp.447-454
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• 2010

레일 피로 열화손상유형들은 크게 레일표면에서 발생하는 결함들과 레일내부에서 진전되어 발생하는 결함들로 구분되어질 수 있다. 본 연구에서는 국내에서 연간 누적통과톤수가 가장 많은 도시철도의 운행조건을 고려하여 현장측정을 통해 레일표면 요철성장률을 분석하였으며, 연마 후 누적통과톤수에 따른 시험편을 현장에서 발췌하여 현미경을 이용한 조직검사, 화학성분검사, 마이크로 비커스 경도시험을 수행하였다. 시험결과 신품레일의 경우 유효탈탄층 제거를 위해 약 0.3mm의 초기연마를 시행해야하며, 예방연마의 경우 전구간을 일괄적으로 연마할 경우와 특정 구간별로 구분하여 연마할 경우에 대하여 2가지 방안을 제시하여 레일표면에서 발생하는 RCF결함을 예방하거나 제거할 수 있도록 제시하였다.

• Journal of Yeungnam Medical Science
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• 제8권2호
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• pp.45-51
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• 1991

저자는 우리나라에서 아직 보고되어 있지 않지만 앞으로 유입될 가능성이 있는 T. tonsurans에 대하여 경험을 넓히고자 미국에서 환자에서 분리한 T. tonsurans에 대상으로 여러가지 진균학적 검사를 실시하여 다음과 같은 결과를 얻었다. 1. 육안적으로 표면은 편평하고 무두질한 양가죽 양상으로 미세한 과립이 얇게 덮혀있고 연한 회색 또는 연한 황색을 나타내었으며 중앙에는 굴곡이 있고 뒷면은 마호가니 갈색을 나타내었다. urease test에서 균주에 따라 다양한 색깔을 나타내었다. 2. 현미경 소견에서 격벽이 있는 균사를 비롯하여 대분생자, 소분생자, spiral hyphae, 후막포자가 발견되었으며 소분생자의 배열과 모양이 특징적으로 균사를 중심으로 양옆으로 배열되어 길고 그 끝이 성냥 끝처럼 부풀어 있었다. 3. 모발천공검사에서 19주중 16주에서 양성소견을 보였다.

• 대한수의학회지
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• 제57권4호
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• pp.227-233
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• 2017

To reduce swine production costs, a slaughter check system has been developed in countries with an advanced swine industry. Evaluation of lung lesions in carcasses is a critical part of the slaughter check system. This study was performed to collect background information for use in developing a slaughter check system in Korea. Lung tissues and their gross images were collected from slaughterhouses in Gyeonggi-do, Korea. Scoring of the gross lung lesions was performed on the lung images. Histopathologic examination was conducted to classify the pulmonary lesions as bronchopneumonia or interstitial pneumonia. Scores of the gross lung lesions were significantly different between bronchopneumonia and interstitial pneumonia groups (p < 0.001). A 90% confidence interval of gross lung lesion scores was established for the bronchopneumonia group, and the lesion scoring had a sensitivity of 100% and specificity of 77.3%. The gross lung lesion scoring test was subjected to a diagnostic distinction evaluation by examining the receiver operating characteristic curve and was appraised as having good discrimination for bronchopneumonia. Establishment of a gross lung lesion scoring test for the diagnosis of bronchopneumonia could be valuable as a screening test of macroscopic bronchopneumonia in swine slaughter check system.

• 한국환경과학회지
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• 제6권3호
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• pp.249-258
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• 1997

Mercury- and cadmium-resistant bacteria were Isolated from an Industrial complex wastewater of Taejon area. All of them were motile, gram negative rods. In the results of physicochemical test and VITEK card test. HM1 was Identified with Achetobacter cd- coaceucus, CM3 was Identified 65 Commonas acidovorns, HM2, HM3, CMI , and CM4 were Pseudomonas sp., but HM4 and CM2 were unidenteed. They were tested for subceptlbility to 14 heavy metals. Mercury-resistant bacteria(HM1, HM2, HM3, and HM4) were sensitive to low concentration(100~400ppm) of $Cd^{2+}$, $Co^{2+}$. $Zn^{2+}$, and Ni2+, while cadmium-resistant bacteria(CM1, CM2, CM3, and CM4) showed resistance up to the high concentration(600~ 1, 200ppm) of these metal loons. As a result of resistance spectrum test of mercury-resistant bacteria, HM1 was broad-spectrum strain, HM2. HM3, and HM4 were narrow-spectrum stratas. Transmission electron microscopic examination of cell wall of HM1 culture grown with and without 100ppm of $HgCl_2$ showed remarkably merphological abnormalities. In the result of atomic absorption spectrometric analysis of cadmium-resistant bacteria grown at 200ppm of $CdCl_2$ for 6h, all of them accumulated cadrnium(14ppm~57ppm) In cell. In cadinium-resistant bacteria, CM1, CM2, and CM4 were spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$, CM4 were also spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$ as well as $Zn^{2+}$.

• 대한치과기공학회지
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• 제34권3호
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• pp.227-235
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• 2012

Purpose: This study compared the surface hardness (Vickers) and microstructural characteristics between a type IV stone with and without die hardening treatment, a polyurethane die material. Methods: Materials used were a type IV stone(MG Crystal Rock), two die hardeners (Hardening bath, Epox-it), and a polyurethane resin material(Polyluck). Six specimens per group were prepared according to manufacturer's directions. The prepared specimens were tested by means of hardness test, one-way ANOVA analysis, scanning electron microscopic(SEM) observations and energy dispersive spectroscopic(EDS) analysis. Results: In the hardness test and its statistical analysis, there was no significant difference in the surface hardness between a type IV stone and type IV stone with die hardener coating, type IV stone mixed with an epoxy like material instead of water. In contrast, polyurethane resin material exhibited significantly greater surface hardness than other specimen groups (p<0.05). Conclusion: By considering the results of the hardness test, SEM observations and EDS analysis, although the die hardeners on type IV stone did not show remarkable improvement in surface hardness, the die hardener coating on the surface of type IV stone material did show decrease of microporous and improvement of surface defects.

• 한국해양공학회지
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• 제26권5호
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• pp.5-10
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• 2012

In this study, carbon steel (A53) is used as the material for the pipes in a marine plant and ship industry. Welds are necessary to join the carbon steel, and the effect of this welding on the properties of the carbon steel has been studied by many researchers. In this study, the dynamic behavior of welded carbon steel was studied using an acoustic emission (AE) technique, which is a nondestructive test. There are numerous AE parameters that can be used to analyze the damage behavior of carbon steel by external loading. The AE parameters of energy, cumulative count, amplitude, and AE event were used, and each parameter was differentiated according to the degree of damage to the carbon steel. The energy showed a high level at the elastic range of the load curve, while the amplitude had the highest value at the hardening region. The cumulative count showed a growth tendency similar to the loading curve. In addition, an ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region, and weld zone of the weld specimen. The velocity and attenuation ratio showed little change between zones, and an evaluation of the ultrasonic waves on each zone of the specimen was found to be a useful method to clarify the mechanical properties of the carbon steel.

• Journal of Periodontal and Implant Science
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• 제31권2호
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• pp.317-332
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• 2001

The purpose of this study was to investigate effects of the natural coral(NC) and the hydroxyapatite/calcium sulfate hemihydrate(HA/CS) on an early stages of wound healing in the rat periodontal fenestration defects. In this experiment, twelve male rats(Mean : 520g in BW) aged 8 to 9 months were used. Experimental periodontal fenestration defects were surgically created with tapered fissure bur at the buccal surface of the left mandibular 1st, 2nd molars. The buccal aspects of molar roots were carefully denuded of their periodontal ligament through a bony window created in the left mandibles of rats under general anesthesia. Each experimental periodontal fenestration defect was grafted with natural coral and HA/CS, randomly. An area without bone graft was assigned for negative control group. At 10,35 days, rats were serially sacrificed via intracardiac perfusion with 2.5% glutaraldehyde and specimens were processed with Hematoxylin-Eosin stain for light microscopic evaluation. The results of this study were as follows : 1. The defect areas were filled with dense connective tissues at 10 days in control group. But in the test(NC, HA/CS)groups, the connective tissues around graft materials were formed more loosely and the response of inflammation by graft materials itself was not found. 2. The defect areas were filled with new osteoid tissues and new cementum was not formed on the cut root surface at 35 days in the control group. 3. New osteoid tissue formation was more prominent at 35 days in control than test groups. 4. The NC and HA/CS particles were encapsulated by loose connective tissues at 10 days and by dense connective tissues at 35 days, respectively. 5. In the test groups, resorption of graft particles was not found through the experimental time. From the above results, natural coral and hydroxyapatite/calcium sulfate hemihydrate may be biocompatible and osteoconductive and have a weak adverse reaction to the periodontal tissues.

• 한국인터넷방송통신학회논문지
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• 제21권6호
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• pp.77-82
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• 2021

요검사는 물리적 성상 검사, 화학적 검사, 현미경 검사 세 가지가 있다. 이 중에서 화학적 요검사는 일반인이 쉽게 접근하는 방법으로 요검사지의 화학반응을 눈으로 표준비색표와 비교하거나 휴대용 요검사기를 별도로 구매하여 검사를 진행한다. 현재는 스마트폰의 보급이 대중화되어 스마트폰을 활용한 요검사 서비스 연구가 높아지고 있다. 요검사 스크리닝 애플리케이션은 스마트폰을 활용한 요검사 서비스 중 하나이다. 그러나 요검사 스크리닝 애플리케이션으로 촬영한 요검사 패드 RGB 값은 조명영향으로 인해 큰 편차가 발생한다. 요검사 패드 RGB 값의 편차는 요검사 판별의 정확도를 떨어뜨린다. 따라서 본 논문에서는 스마트폰 기반 요검사 스크리닝 애플리케이션으로 촬영한 요검사지를 검사 항목별 요검사 패드로 분류한 후 CNN을 통해 요검사 패드 이미지 판별의 정확도를 높인다. 요검사지는 다양한 배경에서 촬영하여 CNN 이미지를 생성하였으며 ResNet-50 CNN 모델을 사용하여 요검사 판별을 분석하였다.

• The Journal of Advanced Prosthodontics
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• 제11권1호
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• pp.23-31
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• 2019

PURPOSE. To investigate and compare the surface roughness (SR), weight and height of monolithic zirconia (MZ), ceramometal (CM), lithium disilicate glass ceramic (LD), composite resin (CR), and their antagonistic human teeth enamel. MATERIALS AND METHODS. 32 disc shaped specimens for the four test materials (n=8) and 32 premolars were prepared and randomly divided. SR, weight and height of the materials and the antagonist enamel were recorded before and after subjecting the specimens to 240,000 wear-cycles ($49N/0.8Hz/5^{\circ}C/50^{\circ}C$). SR, height, weight, and digital microscopic qualitative evaluation were measured. RESULTS. CM ($0.23+0.08{\mu}m$) and LD ($0.68+0.16{\mu}m$) exhibited the least and highest mean difference in the SR, respectively. ANOVA revealed significance (P=.001) between the materials for the SR. Paired T-Test showed significance (P<.05) for the pre- and post- SR for all the materials. For the antagonistic enamel, no significance (P=.987) was found between the groups. However, the pre- and post- SR values of all the enamel groups were significant (P<.05). Wear cycles had significant effect on enamel weight loss against all the materials (P<.05). CR and MZ showed the lowest and highest height loss of 0.14 mm and 0.46 mm, respectively. CONCLUSION. MZ and CM are more resistant to SR against the enamel than LD and CR. Enamel worn against test materials showed similar SR. Significant variations in SR values for the tested materials (MZ, LD, CM, and CR) against the enamel were found. Wear simulation significantly affected the enamel weight loss against all the materials, and enamel antagonist against MZ and CM showed more height loss.

• Toxicological Research
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• 제14권4호
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• pp.547-555
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• 1998

The subchronic toxicity of a combined preparation of ticlopidine and ginkgo biloba extract (EGb 761) mixed in a ratio of 10: 4 was examined in male and female Sprague-Dawley rats. Rats were treated with the test substance at a dose of 52 mg/kg, 156 mg/kg, or 467 mg/kg intragastrically for 30 consecutive days. Control rats were treated with vehicle only. Each group consisted of 10 rats. No death or abnormal clinical signs were observed throughout the administration period. A transient decrease in body weight gain and food intake was observed in the rats treated with the high dose (467 mg/kg), which was recovered to normal in a week. There were no drug-related differences in urinalysis and hematological results. A significant increase in serum total cholesterol and total protein was observed in both sexes of the rats treated with a dose of 467 mg/kg daily, but all the other values obtained in serum chemistry appeared to be within normal range. A dose dependent increase in liver weight was observed in both male and female rats. Relative kidney weight was also increased in the high dose groups. There was no gross pathological finding at terminal sacrifice. Microscopic histopathological examination did not show any lesion in terms of correlation with administration of the test substance. The results suggest that under the conditions employed in this study no observable effect level (NOEL) of the test substance be 52 mg/kg/day.