• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.83-94
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• 2007

Piled raft foundations have been highlighted as an economical design concept of pile foundations in recent years. However, piled raft foundations have not been widely used in Korea due to the difficulty in estimating the complex interaction effects among rafts, piles and soils. The authors developed an effective numerical program to analyze the behavior of piled raft foundations for practical design purposes and presented it briefly in this paper. The developed numerical program simulates the raft as a flexible plate consisting of finite elements with eight nodes and the raft is supported by a series of elastic springs representing subsoils and piles. This study imported another model to simulate pile groups considering non-linear behavior and interaction effects. The apparent stiffnesses of the soils and piles were estimated by iterative calculations to satisfy the compatibility between those two components and the behavior of piled raft foundations can be predicted using these stiffnesses. For the verification of the program, the analysis results about some example problems were compared with those of rigorous three dimensional finite element analysis and other approximate analysis methods. It was found that the program can analyze non-linear behaviors and interaction effects efficiently in multi-layered soils and has sufficient capabilities for application to practical analysis and design of piled raft foundations.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.62-62
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• 2021

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 특히, 국내 하천에서 나타나고 있는 난분해성 유기물 오염도의 증가 추세에 대응한 실효성 있는 유기물 오염관리 정책을 수립하기 위해서는 다양한 유기물의 근원을 정확하게 파악하는 것이 매우 중요하다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 저수지시스템에서의 유기탄소 물질수지를 해석하는 데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2017년을 대상으로 입력자료를 구축한 후 보정을 수행하였고 2018년을 대상으로 모델을 검정하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였다. 유기탄소 물질수지 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였다. 모델은 2017년과 2018년의 물수지를 적절히 재현하였으며 저수지의 성층구조를 잘 재현해내면서 전반적인 수온, 수질을 적절하게 모의하였다. 연간 TOC 부하량 중 내부기원 부하량은 2017년 68.4 %, 2018년은 높은 강우량의 영향으로 55.0%로 산정되었다. 내부 소멸 기작 중 침전으로 인한 손실이 가장 높은 것으로 나타났으며, 2017년과 2018년 각각 31.3%, 29.0%로 나타났다. TOC의 공간분포는 Chl-a 농도 분포와 유사하게 나타났으며, 댐 설치로 형성된 정체수역은 유역의 유기물 순환에 많은 영향을 미치는 것으로 평가되었다. TOC 관리 정책 기초자료 확보를 위해서는 향후 유역-저수지 시스템을 연계한 유기물 물질순환 심층 연구가 필요하다.

• Steel and Composite Structures
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• v.46 no.1
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• pp.53-73
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• 2023

Man-made structure materials like concrete usually contain inclusions. These inclusions affect the mechanical properties of concrete. In this investigation, the influence of inclusion length and inclination angle on three-dimensional failure mechanism of concrete under uniaxial compression were performed using experimental test and numerical simulation. Approach of acoustic emission were jointly used to analyze the damage and fracture process. Besides, by combining the stress-strain behavior, quantitative determination of the thresholds of crack stress were done. concrete specimens with dimensions of 120 mm × 150 mm × 100 mm were provided. One and two holes filled by gypsum are incorporated in concrete samples. To build the inclusion, firstly cylinder steel tube was pre-inserting into the concrete and removing them after the initial hardening of the specimen. Secondly, the gypsum was poured into the holes. Tensile strengths of concrete and gypsum were 2.45 MPa and 1.5 MPa, respectively. The angle bertween inclusions and axial loadind ary from 0 to 90 with increases of 30. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Diameter of the hole was 20 mm. Entirely 20 various models were examined under uniaxial test. Simultaneous with experimental tests, numerical simulation (Particle flow code in two dimension) were carried out on the numerical models containing the inclusions. The numerical model were calibrated firstly by experimental outputs and then failure behavior of models containing inclusions have been investigated. The angle bertween inclusions and axial loadind vary from 0 to 90 with increases of 15. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Entirely 32 various models were examined under uniaxial test. Loading rate was 0.05 mm/sec. The results indicated that when inclusion has occupied 100% of sample thickness, two tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusion has occupied 75% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusions have occupied 50% and 25% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. Also the inclusion was failed by one tensile crack. The compressive strength of samples decease with the decreases of the inclusions length, and inclusion angle had some effects on that. Failure of concrete is mostly due to the tensile crack. The behavior of crack, was affected by the inclusion length and inclusion number.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.951-960
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• 2006

Structural pavement analysis considering lateral loads of moving vehicle was carried out in order to simulate passing vehicle loads under various interface conditions. To verify of existing multi-layer elastic analysis of layer interface effect parameters, this study compared outputs by using ABAQUS, a three dimensional finite element program and KENLAYER, multi-layer elastic analysis as vertical load was applied to the surface of asphalt pavements. Pavement performance depending on interface conditions was quantitatively evaluated and fundamental study of layer interface effect parameters was performed in this study. As results of the study, if only vertical loads of moving vehicle is applied, subdivision of either fully bonded or fully unbonded is enough to indicate interface effect parameters. On the other hand, when lateral loads are applied with vertical loads, pavement behavior and performance are greatly changed with respect to layer interface conditions. The thinner thickness of the asphalt layer is and the smaller elastic moduli of the asphalt layer is, the more pavement behavior is influenced by interface conditions. In addition, regression analysis equation analytically computing tensile strain which was considered thicknesses and elastic moduli of the asphalt layer and layer interface effect parameters at the bottom of the asphalt layer was presented using database from numerical analyses on national pavement model sections.

• Journal of The Korean Association For Science Education
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• v.27 no.7
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• pp.645-662
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• 2007

The purpose of this study was to explore the manners in which models are used in secondary science classrooms. A total of thirteen video-recordings of science lessons dealing with the domains of atmospheric and oceanic earth sciences and their verbatim transcripts were analysed both quantitatively and qualitatively. Interviews with three inservice science teachers were also conducted. Six interrelated assertions were generated as the result of the study: 1) The most frequently used models in secondary earth science classrooms include two-dimensional pictorial, symbolic, iconic, and diagrammatic ones; 2) Science teachers employ models as a mode of representation to make the subject matter available to students; 3) In earth science classrooms, teachers use typical forms of models in intensive manners; 4) Students themselves deal with models on a few occasions, but they just follow similar procedures with the same models; 5) Teachers talk rarely about the nature of scientific models and provide few opportunities for students to think about it; and, 6) Teachers in practice think that the value of using models should be appraised in consideration of the pedagogical intentions of the teacher. Implications for science education and science education research were discussed.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.876-888
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• 2021

Purpose The aim of this study was to compare the diameter and volume of liver metastases on CT images in relation to overall survival and tumor response in patients with gastric cancer liver metastases (GCLM) treated with chemotherapy. Materials and Methods We recruited 43 patients with GCLM who underwent chemotherapy as a first-line treatment. We performed a three-dimensional quantification of the metastases for each patient. An independent survival analysis using the Response Evaluation Criteria in Solid Tumors (RECIST) was performed and compared to volumetric measurements. Overall survival was evaluated using Kaplan-Meier analysis and compared using Cox proportional hazard ratios following univariate analyses. Results When patients were classified as responders or non-responders based on volumetric criteria, the median overall survival was 23.6 months [95% confidence interval (CI), 8.63-38.57] and 7.6 months (95% CI, 3.78-11.42), respectively (p = 0.039). The volumetric analysis and RECIST of the non-progressing and progressing groups showed similar results based on the Kaplan-Meier method (p = 0.006) and the Cox proportional hazard model (p = 0.008). Conclusion Volumetric assessment of liver metastases could be an alternative predictor of overall survival for patients with GCLM treated with chemotherapy.

• Advances in aircraft and spacecraft science
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• v.11 no.1
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• pp.83-103
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• 2024

Adhesive bonding is currently widely used in many industrial fields, particularly in the aeronautics sector. Despite its advantages over mechanical joints such as riveting and welding, adhesive bonding is mostly used for secondary structures due to its low peel strength; especially if it is simultaneously exposed to temperature and humidity; and often presence of bonding defects. In fact, during joint preparation, several types of defects can be introduced into the adhesive layer such as air bubbles, cavities, or cracks, which induce stress concentrations potentially leading to premature failure. Indeed, the presence of defects in the adhesive joint has a significant effect on adhesive stresses, which emphasizes the need for a good surface treatment. The research in this field is aimed at minimizing the stresses in the adhesive joint at its free edges by geometric modifications of the ovelapping part and/or by changing the nature of the substrates. In this study, the finite element method is used to describe the mechanical behavior of bonded joints. Thus, a three-dimensional model is made to analyze the effect of defects in the adhesive joint at areas of high stress concentrations. The analysis consists of estimating the different stresses in an adhesive joint between two 2024-T3 aluminum plates. Two types of single lap joints(SLJ) were analyzed: a standard SLJ and another modified by removing 0.2 mm of material from the thickness of one plate along the overlap length, taking into account several factors such as the applied load, shape, size and position of the defect. The obtained results clearly show that the presence of a bonding defect significantly affects stresses in the adhesive joint, which become important if the joint is subjected to a higher applied load. On the other hand, the geometric modification made to the plate considerably reduces the various stresses in the adhesive joint even in the presence of a bonding defect.

• Journal of Christian Education in Korea
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• v.77
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• pp.127-150
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• 2024

This study seeks to shed light on the contributions of Horst Klaus Berg to German Bible didactics, underscoring the pivotal role of diverse interpretative approaches in the teaching and learning of the Bible. In an era where the complexities and intricacies of the Bible present significant challenges to contemporary readers, the prevalence of one-dimensional interpretations further obstructs the pathway to a profound comprehension of the spiritual depth embedded within its texts. By centering on Horst Klaus Berg's influential theories in the field of German Bible didactics, this research delves into the impact of varied biblical interpretations on Christian education. Berg's work is celebrated for its insightful strategies, notably his advocacy for comprehensive interpretative methods such as "Railway Tracks" and "Free-Learning." These approaches seek to reconcile traditional biblical teachings with individual experiences, thereby facilitating a more expansive understanding of the Bible's applicability to modern life. Through a detailed examination of Berg's theory on biblical interpretation, this paper argues that Christian education must prioritize the cultivation of diverse interpretative skills and their practical integration into Bible study. This educational model encourages learners to become active interpreters, capable of discerning the text's deep-seated meanings by relating it to their personal experiences. The study concludes by affirming Berg's delineation of three critical tasks in biblical interpretation: "reciprocal interpretation," "acknowledgment of the biblical texts' diversity," and "free learning." These elements are portrayed as interrelated and essential, reinforcing Berg's proposition that understanding the Bible's complexity and diversity is crucial for advancing Christian education. This paper offers a novel perspective on the significance of embracing multifaceted interpretations within the domain of biblical studies.

• Journal of the Society of Disaster Information
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• v.20 no.3
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• pp.484-499
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• 2024

Purpose: Recently, due to the aging of safety facilities in national industrial complexes, there has been an increase in the frequency and scale of safety accidents, highlighting the need for a shift toward a prevention-centered disaster management paradigm and the establishment of a digital safety network. In response, this study aims to provide an information system that supports more rapid and precise decision-making during disasters by utilizing digital twin-based integrated control technology to predict the spread of hazardous substances, trace the origin of accidents, and offer safe evacuation routes. Method: We considered various simulation results, such as surface diffusion, upper-level diffusion, and combined diffusion, based on the actual characteristics of hazardous substances and weather conditions, addressing the limitations of previous studies. Additionally, we designed an integrated management system to minimize the limitations of spatiotemporal monitoring by utilizing an IoT sensor-based backtracking model to predict leakage points of hazardous substances in spatiotemporal blind spots. Results: We selected two pilot companies in the Gumi Industrial Complex and installed IoT sensors. Then, we operated a living lab by establishing an integrated management system that provides services such as prediction of hazardous substance dispersion, traceback, AI-based leakage prediction, and evacuation information guidance, all based on digital twin technology within the industrial complex. Conclusion: Taking into account the limitations of previous research, we used digital twin-based AI analysis to predict hazardous chemical leaks, detect leakage accidents, and forecast three-dimensional compound dispersion and traceback diffusion.

• Journal of Global Scholars of Marketing Science
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• v.18 no.1
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• pp.1-31
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• 2008

Trust is central to human relationships, at all times and places. The importance of trust is fundamental in all areas of human life, not only in the area of business administration. 2,500 years ago in China, Confucius taught that the foundation of politics was the trust of the people, more important even than military strength or the supply of food. Shakespeare's play, "Much Ado about Nothing' is about trust and deception. These days, trust and transparency in a commercial organization's business culture form the basis of the 'social capital' by which that organization increases its productivity. A successful company raises productivity by the accumulation of social capital, derived from a trust relationship between business partners, and between the company and consumers. Trust is the crucial factor. At the national level, building trust determines a nation's competitiveness. For a company, long term trust relationships with customers are essential for its survival in a business environment of rapid change. Such relationships, based on trust, are important assets to ensure a company's competitive advantage, and need to be organic to that company's business culture. Because of this importance, trust relationships have been studied in diverse areas within business administration, and especially within marketing, where they form the basis of a successful relationship between producer and consumer. However, what has been lacking is a unified definition of trust. Research has been conducted on the basis of various definitions and models. The majority of researchers have not considered the multidimensional character of the concept of trust until now. Approaches based on a one dimensional model have undermined the value of research results. Furthermore, researchers have only considered trust and trustworthiness as a single component. The majority of research has explored the consequences of perceived trust for outcomes such as loyalty or cooperation, but has neglected the effects of trustworthiness upon the mechanisms of consumer trust. This study focuses on the dimension of trust from such a perspective. It seeks to verify the effect of trust on customer intentions by breaking it down into three separate components: 1) the salesperson, 2) the product/service, and 3) the company. The purposes of this paper are as follows: Firstly, we review the multidimensional nature of trust objects: the salesperson, the product/service, and the company. Secondly, we analyze the relationship between multidimensional trust and trustworthiness. Thirdly, we analyze the connection between trust and repeat purchase intentions for the maintenance of long term relationships. For these purposes the author has developed several hypotheses as follows: H1-1: The competence of a salesperson is positively associated with the trust given by the consumer to the salesperson. H1-2: The benevolence of a salesperson is positively associated with the trust given by the consumer to the salesperson. H2-1: The competence of product/service is positively associated with the trust given by the consumer to the product/service. H2-2: The benevolence of product/service is positively associated with the trust given by the consumer to the product/service. H3-1: The reputation of a company is positively associated with the trust given by the consumer to the company. H3-2: The physical environment of a company is positively associated with the trust given by the consumer to the company. H4-1: Trust in a salesperson is positively associated with repeat purchase intentions. H4-2: Trust in a product/service is positively associated with repeat purchase intentions. H4-3: Trust in a company is positively associated with repeat purchase intentions. The data was compiled from 366 questionnaires. 500 questionnaires were collected, but some of the data was considered unsuitable and inappropriate. The subjects of the survey were male and female customers purchasing products at department stores in Seoul, Daegu and Gyeongbuk. It was carried out between Oct. 25 and 29, 2007. The data was analyzed by frequency analysis using SPSS 12.0 and structural equation modeling using LISREL 8.7. The result of the overall model analysis is as follows: Chi-Square=445.497, d.f.=185, p-value=0.0, GFI=.901, RMSEA=.0617, NNFI=.986, NFI=.981, CFI=.989, AGFI=.864, RMR=.0872. The results of the overall model analysis were coherent. It was found that trust is a multi-dimensional construct, that each of the dimensions of trust are meaningful influences on customer's repurchase intention. Trust in a company may be the most relevant, while trust in a product/service and a salesperson may be less relevant to repurchase intentions. The effective factors in determining trust in a salesperson and a company's product/service were found to be competence and benevolence. Factors in determining trust in a company were its reputation and physical environment, and the relationship of each effective trust factor has been verified in this research. As a result, it was found that competence and benevolence have a meaningful influence on trust in a salesperson and in product/service. It was also found that a company's reputation influences the overall trust in the company significantly but a company's physical environment does not have much effect.