• 한국지반환경공학회 논문집
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• 제10권4호
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• pp.25-31
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• 2009

본 연구의 목적은 기존 흙 포장의 문제점인 장기적인 내구성 결여 및 균열발생을 보완한 친환경적 흙포장재를 개발하기 위한 것이다. 액상형태의 혼합이 용이한 무기질 결합재와 화강풍화토를 첨가량별로 배합하여 일축압축시험 및 투수시험을 실시하였다. 시험결과에 따라 적정 배합비를 산정하고 6가크롬($Cr^{6+}$)검출시험, 재령별 SEM촬영, 동결융해시험을 실시하여 적정성을 검증하였다. 연구 결과, 분말형 무기계 결합재의 배합비는 시멘트:플라이애시:석고의 비율이 각각 50:33:7이 가장 적합한 것으로 판단되었다. 그리고 6가크롬($Cr^{6+}$) 검출시험결과 6가크롬($Cr^{6+}$)의 발생량이 미미하였고, SEM촬영 결과 재령 3일에 에트린자이트 형성이 확인되어 재료가 화학적으로 조기강도 발현이 가능함을 알 수 있었다.

• 대한가정학회지
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• 제47권9호
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• pp.101-110
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• 2009

본 연구의 목적은 온라인 의류 쇼핑환경에서 정보부하가 정보품질지각과 웹사이트 품질지각에 미치는 영향과 정보품질지각과 웹사이트 품질지각, 소비자 행동 의도 간의 관계에 관하여 조사하는데 있다. 정보부하이론은 본 연구의 이론적 틀을 제공하였으며, 가상의 의류 웹사이트를 이용한 온라인 실험을 실시하였다. 총 647명의 응답이 연구 결과 분석에 사용되었다. 연구모형은 MANOVA와 SEM으로 분석하였다. MANOVA 결과는 정보부하가 정보품질지각과 웹사이트 품질지각에 미치는 영향을 지지하였다. 중간 정도의 정보부하가 주어졌을 때가 높은 정도 혹은 낮은 정도의 정보부하가 주어졌을 때 보다 소비자는 가장 높은 정보품질과 웹사이트품질을 지각하였다. SEM 분석 결과 정보품질지각이 높을수록 웹사이트 품질지각이 높은 것으로 나타났으며, 웹사이트 품질지각이 높은 경우 긍정적인 구전을 하며 더 많은 돈을 지불할 의사가 있었고, 다른 웹사이트로 바꿀 의사가 적은 것으로 나타났다. 온라인 의류 소매상 및 웹사이트 디자이너는 정보부하의 중요성을 인식하고, 웹사이트에서 제공하는 정보의 양과 품질을 적절히 조절하여야 할 것이다.

• Genomics & Informatics
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• 제8권3호
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• pp.150-158
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• 2010

Genome-wise association studies (GWASs) have become popular approaches to identify genetic variants associated with human biological traits. In this study, we applied Structural Equation Models (SEMs) in order to model complex relationships between genetic networks and traits as risk factors. SEMs allow us to achieve a better understanding of biological mechanisms through identifying greater numbers of genes and pathways that are associated with a set of traits and the relationship among them. For efficient SEM analysis for GWASs, we developed a procedure, comprised of four stages. In the first stage, we conducted single-SNP analysis using regression models, where age, sex, and recruited area were included as adjusting covariates. In the second stage, Fisher's combination test was conducted for each gene to detect significant genes using p-values obtained from the single-SNP analysis. In the third stage, Fisher's exact test was adopted to determine which biological pathways were enriched with significant SNPs. Finally, based on a pathway that was associated with the four traits in common, a SEM was fit to model a causal relationship among the genetic factors and traits. We applied our SEM model to GWAS data with four central obesity related traits: suprailiac and subscapular measures for upper body fat, BMI, and hypertension. Study subjects were collected from two Korean cohort regions. After quality control, 327,872 SNPs for 8842 individuals were included in the analysis. After comparing two SEMs, we concluded that suprailiac and subscapular measures may indirectly affect hypertension susceptibility by influencing BMI. In conclusion, our analysis demonstrates that SEMs provide a better understanding of biological mechanisms by identifying greater numbers of genes and pathways.

• 한국산업보건학회지
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• 제22권2호
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• pp.119-127
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• 2012

Objectives: The aim of this study is to identify concentration characteristics of indoor and outdoor airborne total fiber particles and asbestos in Gyeongnam Provinces. Methods: This study investigated concentration characteristics of indoor fiber particles from 748 schools and 38 public facilities as well as outdoor particles from 11 sites through PCM (phase contrast microscope). SEM/EDX (scanning electron microscope/energy dispersive using X-ray analysis) was used to obtain physicochemical information of asbestos fiber particles. The study identified asbestos rate in the 15 samples from indoor and outdoor airborne total fiber particles. Results: 1. The average indoor airborne concentrations of total fiber particles were $0.0011{\pm}0007$ f/cc in schools and $0.0015{\pm}0007$ f/cc in public facilities by PCM. Over 90% of the fiber particles were identified as single fibers. 2. The average outdoor airborne concentrations of total fiber particles were $0.0007{\pm}0002$ f/cc, and they were lower than those of indoor airborne concentrations. 3. The results showed that the form of asbestiform was diverse as skein of thread like form and long needle, which was relatively narrower than that of glass fiber and rock wool. 4. The results of SEM/EDX analysis of 15 areas where total fiber particle was relatively high showed that the form was rather similar to that of asbestos, but chemical composition was proven to be non-asbestos. Conclusions: The concentration of indoor and outdoor airborne total fiber particles of Gyeongnam Provinces satisfied the IAQ (Indoor air quality) level of 0.01 f/cc and asbestos was not found in most of the samples by SEM/EDX.

• 콘크리트학회논문집
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• 제21권4호
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• pp.531-537
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• 2009

이 연구에서는 알칼리-실리카 반응성을 평가하는데 적용되는 ASTM C 227과 ASTM C 1260 모르타르 봉 시험법으로 쇄석골재의 반응성을 평가하고, 제작된 모르타르를 3년간 일반 환경에 노출시킨 뒤, 알칼리-실리카 반응으 로 인해 생성될 수 있는 반응생성물 확인과 화학분석을 위해 SEM과 EPMA 분석을 실시하였다. 이 연구에서는 SEM의 secondary electron image(SEI)와 EPMA의 backscattered electron image(BSEI)를 이용하였다. 이 연구에 사용된 쇄석골재 는 ASTM C 227에 의해서는 2년간 뚜렷한 팽창을 나타내지 않았지만, KOH 용액을 이용한 반응촉진법에 의해서는 유 해 가능성이 있는 것으로 나타났다. 모르타르 봉 시험 시행 후, SEM SEI 분석 결과, ASTM C 227에 의해 제작된 모 르타르 봉에서는 골재 입자와 시멘트페이스트 사이에 알칼리-실리카 반응에 의한 흔적이나 pore 내에서 반응생성물이 확인되지 않았다. 하지만 ASTM C 1260에 의한 모르타르 봉에서는 알칼리-실리카 반응의 전형적인 반응생성물로 알려 진 꽃잎형(rosette morphology)의 알칼리-실리카 겔(gel)이 확인되었다. EPMA 분석 결과, ASTM C 227에 의한 모르타르 봉에서도 골재 입자 표면에 부분적으로 미세하게 Al-ASR gel이 확인됨에 따라 ASTM C 227에 의해 2년간 무해한 팽 창을 나타내었던 모르타르 봉에서도 알칼리-실리카 반응이 발생하고 있음을 알 수 있었다. 반응성 촉진 시험 후의 모르 타르의 EPMA 분석 결과에서는 골재 입자에 발생된 균열 내부뿐만 아니라 pore 내부에 알칼리-실리카 겔이 축적되어 있는 것으로 나타났으며, 또한 pore 내에서 확인된 겔이 골재 입자 내부에 생성된 겔에 비해 Ca 함량이 더 풍부한 것 으로 나타났다. 국내에서 생산되는 쇄석골재 사용으로 인하여 구조물 내부에 발생한 변화를 미세구조를 통해 확인한 결 과, 알칼리-실리카 반응에 의한 구조물 열화를 알 수 있었다. 따라서, 국내 쇄석골재 사용량 증가에 따라 새로운 건설에 있어서 알칼리-실리카 반응 방지를 위한 고려가 있어야 할 것으로 판단된다.

• 식물분류학회지
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• 제46권2호
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• pp.187-198
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• 2016

This is the first study to deal in-depth with the achene ultra-structure of the genus Launaea Cass. in Egypt. It focuses on 12 taxa belonging to 10 species of this genus. The achene wall anatomy and surface sculpturing of those taxa were studied using scanning electron microscopy (SEM). Important aspects of the investigated taxa based on the achene characters as well as SEM micrographs of the achene surface and anatomical sections are given. Main and secondary costa of the inner achenes are used for easy differentiation between L. intybacea and L. massauensis.

• 전기학회논문지
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• 제56권9호
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• pp.1638-1642
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• 2007

This paper investigated the destruction effect of the semiconductors by impact of high power electromagnetic wave. The experiments is employed as an open-ended waveguide to study the destruction effects on semiconductor using a 2.45 GHz 600 W Magnetron as a high power electromagnetic wave. The semiconductors are located at a distance of $31cm\sim40cm$ from the open-ended waveguide and are composed of a LED drive circuit for visual discernment. Also the chip condition of semiconductor is observed by SEM(Scanning Electron Microscope) analysis. The semiconductor are damaged by high power electromagnetic wave at about 860 V/m. The SEM analysis of the destructed devices showed onchipwire and bondwire destructions. Based on the result, semiconductor devices should have plan to protect the semiconductor devices form high power electromagnetic wave. And the database from this experiment provides the basis for future investigation.

• Journal of Periodontal and Implant Science
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• 제28권4호
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• pp.809-822
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• 1998

Adequate root preparation in the treatment of periodontal disease often involves mechanical instrumentation to remove plaque, calculus perhaps contaminated cementum. Although meticulous scaling and root planing may remove some cementum, the use of aggressive root planing to remove cementum does not appear warranted. So ultrasonic device and rotary instrument appear to be replacing hand instrument. But it is not clear those instruments make smooth root surface as hand instrument. The roghness of the root surface were evaluate with SEM following instrumentation with Gracey curette, Perio Clean and piezo ultrasonic device(Setlec) with various tip. 20 extracted teeth were used in vitro experiment, and 9 teeth of a patient destined for extraction for periodontal reasons were utilized in vivo experiment. It was demonstrated that hand curette created the smoothest surface, while diamond tip tended to roughen the root surface. But the hand curette, Perio Clean, and piezo ultasonic device with scaler tip tend to remove cementum completely. Piezo ultrasonic device with curette-like tip made the desirable smooth surface with partial removal of cementum.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.133-137
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• 2006

Ion permeability characteristics in nano-polymer membrane structures are performed to investigate the chemical composition and characteristics of MEA(Membrane Electrolyte Assembly) which is one of the most important parts to decide the performance in PEMFC(Polymer Electrolyte Membrane Fuel Cell) system. Subsequently, the MEA manufacturing process is presented for the uniformed MEA product. In the meantime, the analysis of SEM(Scanning Electron Microscope) is carried out in order to investigate the joint aspect and chemical composition of MEA. As a result of SEM analysis, it is found that the bonded catalyst and carbon composition contain the reasonable amount to get unit cell output. It is also found that the humidification gives the better performance result slightly.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.379-391
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• 2010

In order to understand the mechanism of cementation of soft soils treated with bacteria, three types of specimens(untreated, normal bacteria concentration treated, and high bacteria concentration treated) were made. Scanning Electron Microscope(SEM), EDX and X-ray diffraction(XRD) analyses were performed on the soft silt and loose sand specimens. Compared with the untreated specimen, a clearer cementation between particles was observed in the high bacteria concentration treated specimen. Based on the scanning electron microscope(SEM) EDX analyses, more calcium carbonate was observed in the specimen treated with high bacteria concentration than other specimens. On the basis of the preliminary results, it appears that microbial cementation can occur in the soft soil. Further study on the cementation of soils using bacteria is necessary to validate this result.