• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.529-534
• /
• 2009

This study had propose that a characteristic of recently developed Silicasol to make a close in this study, grouting material usually used portland cement and a characteristic is compared between Silicasol and sodium silicate in this study, examined strength and environmentally friendly for compare characteristics of sodium silicate and Silicasol through unconfined compressive strength, SEM analysis, Permeability test, Chemical Resistance test, leaching test etc. In the test, I gained that unconfined compressive strength of Silicasol three times promoted than sodium silicate Within 72 hours and I gined through analysis of SEM that Silicasol is more compactivetive than sodium silicate. In the result of test, it was found to be a environmentally friendly material as the toatal amount of eluviated elementary had small quantity.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.501-502
• /
• 2006

In this paper, new and aging sample of MCCB and ELCB are investigated the main performance test such as short circuit test, mechanical and electrical endurance test, dielectric test and surge current test. The surface conditions of new and aging sample are analyzed by SEM, TGA and DSC. The ELCB occurred badness mainly in short circuit test and surge current test. The badness cause of short circuit test was confirmed due to imperfect contact of contact part.

• 한국안전학회지
• /
• 제33권3호
• /
• pp.8-14
• /
• 2018

Ni-base superalloy has excellent resistance to extreme environments such as high temperatures and high stresses and are used as materials for large gas turbines. In this paper, the specimens were taken from the blade that were used for a long time, and their life span was studied by microstructure analysis and avoidance of cursing. The microstructural analysis of the specimens was carried out using a OM and SEM to observe the coarsening, carbides on gamma prime. Low-cycle fatigue tests were performed on new material and airfoil of long time-used blade. The test was conducted under various deformation conditions and temperature conditions of $760^{\circ}C$ and $870^{\circ}C$. The low cycle fatigue test was carried out using the Coffin-Manson equation and the fatigue life was predicted. After the test, crack path and fracture surface were analyzed using SEM.

• Steel and Composite Structures
• /
• 제33권2호
• /
• pp.299-306
• /
• 2019

The natural fibre composites are termed as bio-composites. They have shown a promising replacement to the current carbon/glass fibre reinforced composites as environmental friendly materials in specific applications. Natural fibre reinforced composites are potential materials for various engineering applications in automobile, railways, building and Aerospace industry. The natural fibre selected to fabricate the composite material is plant-based fibre e.g., sisal fibre. Sisal fibre is a suitable reinforcement for use in composites on account of its low density, high specific strength, and high hardness. Epoxy is a thermosetting polymer which is used as a resin in natural fibre reinforced composites. Hand lay-up technique was used to fabricate the composites by reinforcing sisal fibres into the epoxy matrix. Composites were prepared with the unidirectional alignment of sisal fibres. Test specimens with different fibre orientations were prepared. The fabricated composites were tested for mechanical properties. Impact test, tensile test, flexural test, hardness test, compression test, and thermal test of composites had been conducted to assess its suitability in industrial applications. Scanning electron microscopy (SEM) test revealed the microstructural information of the fractured surface of composites.

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

• 한국지반공학회논문집
• /
• 제28권9호
• /
• pp.85-95
• /
• 2012

유기산 재료를 이용한 지반 개량은 미생물을 배양하여 지반의 고결화로 인해 친환경적으로 지반의 강도를 증대시키는 방법으로 다양한 토질 성상에 대해 유기산 재료를 혼합 후 미생물 증식으로 강도 증대효과를 규명한 바가 있으나, 현재까지 현장 적용성을 평가한 바가 없다. 본 논문에서는 유기산재료를 이용하여 지반의 미생물 증식으로 인한 지반 고결화에 대해 연구를 실시하였으며, 이를 위해 재령 56일까지 동평판재하시험, 동적콘관입시험, 들밀도시험, SEM-EDS분석을 통해 지반강도의 변화에 대해 규명하였다. 시험 결과, 유기산 재료를 첨가한 지반의 강도와 강성은 증가하는 경향을 나타냈으며, SEM-EDS로부터 탄산칼슘의 증가를 규명할 수 있었다. 향후 유기산 재료를 활용한 친환경적인 지반개량 공법의 지속적인 연구와 관심이 필요하다고 사료된다.

• Journal of Information Technology Applications and Management
• /
• 제31권1호
• /
• pp.11-25
• /
• 2024

The purpose of this study is to investigate the improvement of prediction performance and changes in variable importance in SEM-ANN two-stage analysis. 366 cosmetics repurchase-related survey data were analyzed and the results were presented. The results of this study are summarized as follows. First, in SEM-ANN two-stage analysis, SEM and ANN models were trained with train data and predicted with test data, respectively, and the R² was showed. As a result, the prediction performance was doubled from SEM 0.3364 to ANN 0.6836. Looking at this degree of R² improvement as the effect size f² of Cohen (1988), it corresponds to a very large effect at 110%. Second, as a result of comparing changes in normalized variable importance through SEM-ANN two-stage analysis, variables with high importance in SEM were also found to have high importance in ANN, but variables with little or no importance in SEM became important in ANN. This study is meaningful in that it increased the validity of the comparison by using the same learning and evaluation method in the SEM-ANN two-stage analysis. This study is meaningful in that it compared the degree of improvement in prediction performance and the change in variable importance through SEM-ANN two-stage analysis.

• PNF and Movement
• /
• 제20권3호
• /
• pp.399-408
• /
• 2022

Purpose: This study investigated the differences in winged scapula between the symptomatic side and asymptomatic side, the reliability of the winged scapula test, and the correlation between winged scapula and the stability of the scapula in patients with subacromial impingement syndrome. Methods: Twenty-four patients with unilateral subacromial impingement syndrome participated in this study. Winged scapula was compared between the symptomatic and asymptomatic sides using a scapulometer. The reliability of the scapulometer was assessed by calculating the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal clinically important difference (MCID). The correlation between winged scapula and the results of the upper quarter Y-balance test were also obtained. Conclusion: Winged scapula was significantly greater on the symptomatic side compared with the asymptomatic side (p < 0.05). High to excellent ICCs were obtained for the winged scapula test, and SEM and MCID values were obtained for winged scapula (SEM: 0.2-0.3 cm, MCID: 0.6-0.8 cm); however, winged scapula and the results of the upper quarter Y-balance test were not correlated. Conclusion: The scapulometer is useful for measuring winged scapula in patients with subacromial impingement syndrome.

• 한국산업융합학회 논문집
• /
• 제27권2_2호
• /
• pp.397-402
• /
• 2024

Silicon carbide materials undergo an oxidation reaction in a high-temperature oxidizing environment and show different characteristics depending on the test temperature and time. In particular, the added oxides form a secondary phase within the sintering process and exhibit different oxidation characteristics depending on the added sintering materials. Therefore, to evaluate the oxidation characteristics, the weight of the test piece and the thickness of the oxidation layer were observed, and the structure and oxidation characteristics of the material were analyzed using SEM. SEM observation showed that an oxide layer was formed on the surface of the liquid sintered silicon carbide material after it was oxidized at 1200 ℃, 1300 ℃, and 1400 ℃ for 10 hours, respectively. Then, a bending test was performed at each temperature on the test piece with the oxidation layer formed to evaluate the change in flexural strength. The strength was 466.6 MPa at 1200 ℃, 363.1 MPa at 1300 ℃, and 350.8 MPa at 1400 ℃. Al₂O₃-SiO₂ oxidized at 1200 ℃ for 10 hours showed an increase in strength of about 21.0 MPa compared to the data before the oxidation test.

• 한국융합학회논문지
• /
• 제10권5호
• /
• pp.95-102
• /
• 2019

본 연구는 정상 성인을 무작위로 급속안구움직임(saccadic eye movement, SEM)군과 의식적손가락움직임(intentional finger movement, IFM) 군으로 구분하여 2주 동안 중재를 실시한 후 숫자외우기 검사와 n-back 검사를 사용하여 인지기능의 변화를 알아보았다. 그 결과 IFM군의 단기기억은 시간이 지날수록 유의하게 상승하였으며, 추적 검사에서는 군간 차이를 나타내었다. IFM군의 n-back은 수행시간, 오류횟수, 정확률에서 시간이 지날수록 유의한 효과를 나타내었다. SEM군의 n-back은 수행시간과 정확률에서 시간이 지날수록 유의한 효과를 나타내었다. 결론적으로 인지기능 향상에는 단일 자극인 SEM보다 대뇌겉질을 광범위하게 활성화 시킬 수 있는 다중 자극인 IFM 방법이 인지기능 향상의 중재 방법으로 더 유용할 것으로 생각된다.