• 한국학교수학회논문집
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• 제15권3호
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• pp.585-603
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• 2012

본 연구에서는 경로분석을 이용하여 TIMSS 2007의 수학 성취도 국제 비교 연구 결과를 바탕으로 학생의 배경 요인이 수학 성취도에 미치는 영향력을 비교하고 각 요인들 사이의 상관관계 및 인과관계에 대하여 분석하고자 하였다. 수학 성취도에 영향을 미치는 요인으로는 이전의 연구들을 바탕으로 학생의 배경에 대한 설문들 중 가정의 장서보유량, 어머니의 최종학력, 아버지의 최종학력, 교육포부, 학생의 정의적 성취지수, 스스로 학습활동 빈도, 그리고 숙제횟수의 총 7 가지 변수들을 설정하여 각 변수들이 수학 성취도에 어떻게 영향을 미치는지, 또한 각 변수들 사이에는 어떤 인과관계가 성립하는지 살펴보았다. 그 결과 부모의 최종 학력, 장서보유량, 정의적 성취지수는 교육 포부에 영향을 주어 학업성취도에 간접적인 영향을 주는 것으로 파악되었다. 교육포부와 정의적 성취지수, 숙제 회수는 학업 성취도에 직접적인 영향을 주는 것으로 나타났다.

• The Journal of Asian Finance, Economics and Business
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• 제8권11호
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• pp.133-143
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• 2021

This study investigates the relationship between social capital and enterprise performance with knowledge sharing as the mediator. By employing the data of 677 respondents collected from delivering questionnaires to small and medium-size firms in Vietnam in 2020, this study suggests a two-step approach that combines exploration factor analysis (EFA), confirmatory factor analysis (CFA), and path analysis (SEM). The empirical findings significantly support our proposed model by demonstrating that knowledge sharing mediates the connection between all three elements of social capital and enterprise performance. At the same time, the results emphasize the importance of knowledge sharing as a major benefit of social capital and a substantial driving element of both operational and financial performance. The results show that all three social capital qualities (structural, relational, and cognitive) significantly impact both tacit and explicit knowledge sharing, while knowledge is one of the main routes connecting social capital to enterprise performance. Hence, our research model may be used in future studies to evaluate social capital, knowledge sharing, and firm performance as a new theoretical model. Our results offer a plausible explanation for how social capital improves knowledge sharing and enterprise performance.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.897-911
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• 2021

This study aims to analyze the important role of business analytics capability, information quality, and innovation capability in influencing organization agility and organization performance during the Covid-19 pandemic. Data was collected from 76 companies from various sectors in Indonesia. Structural Equation Model-Partial Least Square (SEM-PLS) analysis was conducted to analyze the relationship between variables and test a series of hypotheses. Importance-Performance Matrix Analysis (IPMA), a useful analysis approach in PLS-SEM, is used, which extends the results of the estimated path coefficient (importance) by adding a dimension that considers the average values of the latent variable scores (performance). The IPMA approach examines not only the performance of an item but also the importance of that item. The results show that business analytics capability has a significant effect on information quality and innovation capability which then affects organization agility. Organizational performance is influenced by organizational agility. IPMA results show that organizational agility has the highest level of impact on organizational performance. This study will assist companies in planning business analytics, improving information quality, increasing innovation capability, and ultimately increasing agility and performance during the Covid-19 pandemic. This study will add to existing knowledge about previous literature, especially in the Covid-19 pandemic situation.

• 공업화학
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• 제9권7호
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• pp.1023-1029
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• 1998

5Cr-1Mo steel을 이용하여 나트륨 분위기에서 미량 물 누출 실험을 수행하였다. 시편에서 미량 물 누출로 인한 누출경로의 완전 re-open time은 129분으로 나타났고, 그 크기는 직경 2mm를 나타냈다. 누출경로는 re-open되기 전에 누출부위를 중심으로 halos현상을 형성하였으며, halos의 크기와 실제 re-open크기와는 다르게 나타났다. 나트륨-물 반응으로 인한 재질의 부식은 나트륨부위로부터 시작되었으며, steam 부위에서는 부식이 발생하지 않았다. 시편 누출부위를 AES로 분석한 결과 Cr의 segregation이 가장 많이 나타났으며, SEM과 EPMA 관찰로부터 나트륨화합물들이 누출부위 주변에 대량 침적되어 있는 것이 관찰되어 나트륨 철 크롬혼합물 형태로 부식생성물들이 혼재되어 있는 것으로 예측되었다.

• 한국정보통신학회논문지
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• 제19권3호
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• pp.747-755
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• 2015

본 연구는 Pender [11]의 건강 증진모형을 활용하여 유헬스의 행위 의도를 분석하는데 그 목적을 두고 있다. 분석을 위하여 유효한 설문지 216부를 갖고 부분최소자승 기반 구조방정식 방법을 활용하여 제시된 모형을 검증하였다. 분석 결과, 개인적 건강관리 경험 요인이 자기효능감 요인으로의 경로와 자기효능감 요인이 행위 의도로의 경로가 가장 높은 것으로 나타났다. 또한 제시된 모형에서는 유헬스 시스템에 대한 자기 효능감이 높을수록 건강증진행위에 영향을 미치는 유일한 요인임을 확인할 수 있었다. 하지만 본 연구의 수집된 데이터의 적은 표본 수 및 유헬스에 대한 구체성이 다소 떨어진다는 점에서 세부적인 추가 연구가 이어져야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제48권1호
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• pp.4.1-4.10
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• 2023

Objectives: This study aimed to compare the torsional and cyclic fatigue resistance of ProGlider (PG), WaveOne Gold Glider (WGG), and TruNatomy Glider (TNG). Materials and Methods: A total of 15 instruments of each glide path system (n = 15) were used for each test. A custom-made device simulating an angle of 90° and a radius of 5 millimeters was used to assess cyclic fatigue resistance, with calculation of number of cycles to failure. Torsional fatigue resistance was assessed by maximum torque and angle of rotation. Fractured instruments were examined by scanning electron microscopy (SEM). Data were analyzed with Shapiro-Wilk and Kruskal-Wallis tests, and the significance level was set at 5%. Results: The WGG group showed greater cyclic fatigue resistance than the PG and TNG groups (p < 0.05). In the torsional fatigue test, the TNG group showed a higher angle of rotation, followed by the PG and WGG groups (p < 0.05). The TNG group was superior to the PG group in torsional resistance (p < 0.05). SEM analysis revealed ductile morphology, typical of the 2 fracture modes: cyclic fatigue and torsional fatigue. Conclusions: Reciprocating WGG instruments showed greater cyclic fatigue resistance, while TNG instruments were better in torsional fatigue resistance. The significance of these findings lies in the identification of the instruments' clinical applicability to guide the choice of the most appropriate instrument and enable the clinician to provide a more predictable glide path preparation.

• Restorative Dentistry and Endodontics
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• 제38권1호
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• pp.21-25
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• 2013

Objectives: The aim of this study was to evaluate the shaping ability of newly marketed single-file instruments, Wave One (Dentsply-Maillefer) and Reciproc (VDW GmbH), in terms of maintaining the original root canal configuration and curvature, with or without a glide-path. Materials and Methods: According to the instruments used, the blocks were divided into 4 groups (n = 10): Group 1, no glide-path / Wave One; Group 2, no glide-path / Reciproc; Group 3, #15 K-file / Wave One; Group 4, #15 K-file / Reciproc. Pre- and post-instrumented images were scanned and the canal deviation was assessed. The cyclic fatigue stress was loaded to examine the cross-sectional shape of the fractured surface. The broken fragments were evaluated under the scanning electron microscope (SEM) for topographic features of the cross-section. Statistically analysis of the data was performed using one-way analysis of variance followed by Tukey's test (${\alpha}$ = 0.05). Results: The ability of instruments to remain centered in prepared canals at 1 and 2 mm levels was significantly lower in Group 1 (p < 0.05). The centering ratio at 3, 5, and 7 mm level were not significantly different. Conclusions: The Wave One file should be used following establishment of a glide-path larger than #15.

• Structural Engineering and Mechanics
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• 제4권5호
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• pp.513-527
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• 1996

In this paper, both an approximate expression and an exact expression for the contribution factor of an element to the natural frequency of the finite element discretized system of a structure in general and a membrane in particular have been derived from the energy conservation principle and the finite element formulation of structural eigenvalue problems. The approximate expression for the contribution factor of an element is used to predict and determine the elements to be removed in an iteration since it depends only on the quantities associated with the old system in the iteration. The exact expression for the contribution factor of an element makes it possible to check whether the element is correctly removed at the end of an iteration because it depends on both the old system and the new system in the iteration. Thus, the combined use of the approximate expression and the exact expression allows a considerable number of elements to be removed in a single iteration so that the efficiency of the evolutionary structural optimization method can be greatly improved for solving the natural frequency optimization problem of a structure. A square membrane with different boundary supports has been chosen to investigate the general evolutionary path for the fundamental natural frequency of the structure. The related results indicated that if the objective of a structural optimization is to raise the fundamental natural frequency of the structure to an optimal value, the general evolutionary path during its optimization is that the elements are gradually removed along the direction from the area surrounded by the contour of the highest value to that surrounded by the contour of the lowest value.

• 한국재난정보학회 논문집
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• 제18권4호
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• pp.786-794
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• 2022

건설현장에서는 사후적 안전관리를 벗어나 실효성 있는 예방적 안전관리가 요구되고 있다. 연구목적: 본 연구는 자율적이고 예방적 안전관리를 위한 안전관리 활동, 안전문화 핵심요소, 안전, 불안전 행동관리, 안전성과의 관계모형을 제시하고 그 관계를 분석하는 것이 목적이다. 연구방법:설문조사 데이터를 구조방정식에 적용하여 관계를 분석하고, 검증된 가설이 시사하는 부분을 해석하여 외생변수로부터 안전성과에 도달하는 경로를 탐색하고 주요 논점을 제시하였다. 연구결과: 예비모형과 경로모형을 분석한 결과, 적합한 모형적합도를 확인하였고 외생변수가 내생변수에 미치는 유의한 결과를 확인하였다. 결론: 안전관리 활동, 안전, 불안전 행동관리, 안전문화 핵심요소관리로 안전사고 발생 전에 지속적인 안전성과 향상에 효과가 있을 것으로 판단된다.

• 한국주조공학회지
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• 제30권1호
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• pp.34-45
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• 2010

The effects of alloy elements and cooling rate on the solidification path and the formation behavior of $\beta$ phase in Fe-containing Al-Si alloys were studied based on the thermodynamic analysis and the pertinent experiments. The thermodynamic calculation was systematically performed by using Thermo-Calc program. For the thermodynamic analysis in high alloy region of Al-Si-Fe ternary system, a thermodynamic database for Thermo-Calc was correctly updated and revised by the collected up-to-date references. For the thermodynamic-based prediction of various solidification paths in Fe-containing Al-Si system, liquidus projection of Al-Si-Fe ternary system, including isotherms, invariant, monovariant, bivariant reactions and equilibrium temperatures, was calculated and analyzed as functions of composition and temperature. The calculated results were compared to the experimental results using various casting specimens. In order to analyze various solidification sequences as functions of Si and Fe content, 4 representative alloy compositions, low Fe content in both low and high Si contents and high Fe content again in both low and high Si contents, were designed in this study. For better understanding of the influence of cooling rate on the formation behavior of $\beta$ phase, 4 alloys were solidified under furnace and rapidly cooled conditions. Cooling curves of solidified alloys were recorded by thermal analysis. Various important solidification events were evaluated using the first derivative-cooling curves. Microstructures of the casting samples were studied by the combined analysis of optical microscopy (OM) and scanning electron microscopy (SEM).