• Earthquakes and Structures
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• 제23권2호
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• pp.129-138
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• 2022

One of the objectives to prevent building pounding between two adjacentstructures is to considerseparation distance or decrease relative displacement during seismic excitation. Although the majority of building codes around the world have basically suggested some equations or approximately recommended various distances between structuresto avoid pounding hazard, but a lot of reportsin zone of pounding have obviously shown thatsafety situation or economic consideration are not always provided due to the collisions between buildings and the cost of land, respectively. For this purpose, a dynamic MDOF model by having base isolation system is numerically considered and using various earthquake records, relative displacements are mathematically investigated. Different equations to determine the value of damping ratio are collected and the results of evaluations are listed for comparison among them to present a new equation for determination of impact damping ratio. Presented equation is depends significantly on impact velocity before and after impact based on artificial neural network, which the accuracy of them is investigated and also confirmed. In order to select the optimum equation, hysteresisloop of impact between base of building and rubber bumper is considered and compared with the hysteresis loop of each impact, calculated by different equations. Finally, using representative equation, the effect of thickness, number and stiffness of rubber bumpers are numerically investigated. The results of analysis indicate that stiffness and number of bumpers have significantly affected in zone of impact force while the thickness of bumpers have not shown significant influence to calculate impact force during earthquake. For instance, increasing the number of bumpers, gap size between structures and also the value of stiffness is caused to decrease impact force between models. The final evaluation demonstrates that bumpers are able to decrease peak lateral displacement of top story during impact.

• Geomechanics and Engineering
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• 제31권4호
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• pp.339-352
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• 2022

Studying slope stability is an important branch of civil engineering. In this way, engineers have employed machine learning models, due to their high efficiency in complex calculations. This paper examines the robustness of various novel optimization schemes, namely equilibrium optimizer (EO), Harris hawks optimization (HHO), water cycle algorithm (WCA), biogeography-based optimization (BBO), dragonfly algorithm (DA), grey wolf optimization (GWO), and teaching learning-based optimization (TLBO) for enhancing the performance of adaptive neuro-fuzzy inference system (ANFIS) in slope stability prediction. The hybrid models estimate the factor of safety (F_S) of a cohesive soil-footing system. The role of these algorithms lies in finding the optimal parameters of the membership function in the fuzzy system. By examining the convergence proceeding of the proposed hybrids, the best population sizes are selected, and the corresponding results are compared to the typical ANFIS. Accuracy assessments via root mean square error, mean absolute error, mean absolute percentage error, and Pearson correlation coefficient showed that all models can reliably understand and reproduce the F_S behavior. Moreover, applying the WCA, EO, GWO, and TLBO resulted in reducing both learning and prediction error of the ANFIS. Also, an efficiency comparison demonstrated the WCA-ANFIS as the most accurate hybrid, while the GWO-ANFIS was the fastest promising model. Overall, the findings of this research professed the suitability of improved intelligent models for practical slope stability evaluations.

• 한국지반신소재학회논문집
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• 제22권4호
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• pp.1-8
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• 2023

우주 탐사는 인류의 과학적 노력 중 가장 선두에 있으며, 행성 탐사 로버는 행성 지표면을 연구하는 핵심 장비이다. 행성 로버의 성능은 가파른 경사와 다양한 행성 지형을 탐지하고 통과하는 데 큰 영향을 미치며 특히 달과 같은 행성에서는 급격한 경사와 연약한 지면을 안전하게 등반하고 이동할 수 있는 능력이 필수적으로 요구된다. 이 논문에서는 우주 행성 탐사 로버가 직면하는 가파른 지형과 연약한 지면을 모사하는 등반 시험장의 설계와 검증 방법을 종합적으로 소개한다. 먼저 달의 크레이터 지역의 지형 특성과 탐사의 중요성을 간략히 설명하고, 기존 등반 시험장의 개발 사례를 살펴보며, 현재 한국건설기술연구원에서 운영 중인 지반열진공챔버 내에 설치 예정인 등반 시험장의 설계 과정을 설명한다. 본 연구에서 제안하는 등반 시험장이 개발되면 실제 달의 환경과 유사한 고진공, 극한 온도 조건에서 로버의 이동과 탐사 능력을 정밀하게 평가할 수 있을 것으로 기대된다.

• 지식경영연구
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• 제24권3호
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• pp.127-148
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• 2023

전통적인 비즈니스 인텔리전스 환경은 빠르게 변하는 시장과 기하급수적으로 증가하는 데이터의 크기와 복잡성에 대처하는 데 한계를 보여왔다. 이에 기업들은 경쟁사 대비 더 빠르고 정확한 의사결정을 위해 사용자 주도 비즈니스 인텔리전스(Self-Service Business Intelligence) 환경으로의 변모를 요구받고 있다. 그러나 실제 기업 현장에서는 사용자 주도 비즈니스 인텔리전스 환경 구축과 운영에 어려움을 겪고 있으며, 참고할 만한 사례를 포함하여 성공적인 사용자 주도 비즈니스 인텔리전스에 관한 연구가 부족하다. 이에 본 연구에서는 비즈니스 인텔리전스 시스템의 핵심성공요인에 관한 기존 연구 방법론을 기반으로, 국내 3사 제조업 및 유통업체의 비즈니스 인텔리전스 개발 과정 및 활용 사례를 상세하고 깊이 있게 분석하였다. 조직-프로세스-기술 측면 7가지 핵심 성공요인에 대해 개발 목적과 구현 전략이 상이한 세가지 국내 사례를 비교 분석함으로써 비즈니스 인텔리전스 성공모델의 국내 기업 적용 가능성과 도입 전략의 시사점을 도출한다. 해당 프로젝트를 주도한 전문가들의 심층 인터뷰와 도입효과 평가를 통한 심층 비교 분석은, 사용자 주도 비즈니스 인텔리전스의 구체적인 개발 과정과 난제, 활용에 대한 풍부한 시사점을 제공하고 기업의 비즈니스 인텔리전스 활성화와 사용자 주도 비즈니스 인텔리전스 고도화에 기여할 것으로 기대된다.

• 한국표면공학회지
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• 제56권6호
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• pp.437-442
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• 2023

This research aims to enhance the efficiency of Pt/C catalysts due to the limited availability and high cost of platinum in contemporary fuel cell catalysts. Nano-sized platinum particles were distributed onto a carbon-based support via the polyol process, utilizing the metal precursor H₂PtCl₆·6H₂O. Key parameters such as pH, temperature, and RPM were carefully regulated. The findings revealed variations in the particle size, distribution, and dispersion of nano-sized Pt particles, influenced by temperature and pH. Following sodium hydroxide treatment, heat treatment procedures were systematically executed at diverse temperatures, specifically 120, 140, and 160 ℃. Notably, the thermal treatment at 140 ℃ facilitated the production of Pt/C catalysts characterized by the smallest platinum particle size, measuring at 1.49 nm. Comparative evaluations between the commercially available Pt/C catalysts and those synthesized in this study were meticulously conducted through cyclic voltammetry, X-ray diffraction (XRD), and field-emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM EDS) methodologies. The catalyst synthesized at 160 ℃ demonstrated superior electrochemical performance; however, it is imperative to underscore the necessity for further optimization studies to refine its efficacy.

• Steel and Composite Structures
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• 제51권1호
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• pp.25-41
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• 2024

The measurement of pile bearing capacity is crucial for the design of pile foundations, where in-situ tests could be costly and time needed. The primary objective of this research was to investigate the potential use of fuzzy-based techniques to anticipate the maximum weight that concrete driven piles might bear. Despite the existence of several suggested designs, there is a scarcity of specialized studies on the exploration of adaptive neuro-fuzzy inference systems (ANFIS) for the estimation of pile bearing capacity. This paper presents the introduction and validation of a novel technique that integrates the fire hawk optimizer (FHO) and equilibrium optimizer (EO) with the ANFIS, referred to as ANFIS_FHO and ANFIS_EO, respectively. A comprehensive compilation of 472 static load test results for driven piles was located within the database. The recommended framework was built, validated, and tested using the training set (70%), validation set (15%), and testing set (15%) of the dataset, accordingly. Moreover, the sensitivity analysis is performed in order to determine the impact of each input on the output. The results show that ANFIS_FHO and ANFIS_EO both have amazing potential for precisely calculating pile bearing capacity. The R² values obtained for ANFIS_FHO were 0.9817, 0.9753, and 0.9823 for the training, validating, and testing phases. The findings of the examination of uncertainty showed that the ANFIS_FHO system had less uncertainty than the ANFIS_EO model. The research found that the ANFIS_FHO model provides a more satisfactory estimation of the bearing capacity of concrete driven piles when considering various performance evaluations and comparing it with existing literature.

• 한국건축시공학회지
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• 제24권1호
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• pp.23-34
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• 2024

본 연구의 목적은 RC 구조물의 균열 보수용 폴리머 시멘트 복합체의 휨접착성능을 평가하기 위함이다. 시멘트 모르타르에 다양한 크기의 균열을 만들어 PCCs를 충전한 후, 소정의 양생을 거쳐 휨접착강도와 휨강도 개선 정도를 파악하였다. 연구결과, 균열보수용 PCCs의 휨접착강도는 시멘트의 종류, 폴리머 종류 및 폴리머 결합재비에 따라 영향을 받으며 실리카퓸을 혼입한 초조강시멘트를 사용한 경우가 보통시멘트를 사용한 경우에 비해 최대 19.0%의 휨접착강도 개선효과가 나타났다. PCCs로 충전된 시멘트 모르타르의 휨강도 개선 정도는 균열폭의 영향보다는 균열깊이에 따라 큰 차이를 보였으며 균열에 충전된 PCCs가 단순히 보수재료로서 기능뿐만 아니라 어느 정도 휨강도를 개선시키는 보강재료로서도 역할을 하였다. 본 연구결과, 초조강시멘트, 3종류의 폴리머 디스퍼전과 실리카퓸, 60%~80%의 높은 폴리머 결합재비로 제작한 PCCs가 균열을 충전하는 보수재료로서 현장에서 충분히 사용될 수 있을 것이다.

• 대한예방한의학회지
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• 제28권1호
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• pp.43-57
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• 2024

Objectives : The aim of this study was to identify the effect of Medical humanities curriculum on students of Korean medical school in terms of cognitive, affective, and psychomotor level of humanities skill. Methods : The course was taught to second- and third-year Korean medicine students. The classes were held eight times a semester for second-year students and 9 times for third-year students, and each class was held once a week for 2 hours. Formative and summative assessments, group and individual assignments, and peer assessments were conducted to evaluate educational effectiveness, as well as basic lecture evaluations and satisfaction surveys. Results : Most of the students who took Medical humanities showed a performance rate of more than 60-70% in the cognitive aspect, and the total score was 14.48 with a standard deviation of 2.70 in the knowledge application stage. In terms of class satisfaction, students in Medical humanities I were more satisfied with the evaluation criteria and class management expertise, while students in Medical humanities II were most satisfied with the class organization, with an average score of 4.86/5. Conclusions : It was confirmed that students' humanities improved in cognitive, affective, and psychological aspects after medical humanities courses, and future research should be conducted on the long-term educational effects of medical humanities, effective teaching methods, and evaluation methods.

• Journal of Medicine and Life Science
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• 제21권2호
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• pp.31-39
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• 2024

This study was conducted to determine whether level-1 emergency medical technicians (EMTs) can adequately recognize ST-segment elevation myocardial infarction (STEMI) in the emergency department (ED) and whether their ability to do so differs from that of emergency medicine physicians (EMP). From December 2022 to November 2023, patients aged 20 years or older visiting the ED with chief complaints suggesting acute coronary syndrome (ACS) were enrolled. As soon as the patient arrived at the ED, a level-1 EMT conducted a 12-lead electrocardiogram (ECG) to assess STEMI; an EMP subsequently assessed whether to activate the percutaneous coronary intervention team. Demographic characteristics, test results, and final diagnoses were collected from the medical records. Among the 723 patients with case report forms, 720 were included in the analysis. These were categorized as follows: 117 (16.3%) with STEMI, 159 (22.1%) with non-ST-segment elevation ACS, and 444 (61.7%) with other conditions. STEMI was correctly recognized in 100 patients (91.7%) by level-1 EMTs and in 104 patients (95.4%) by EMPs (kappa=0.646). EMTs with less than 1 year of ED work experience correctly recognized 60 out of 67 STEMI patients (89.6%), which was comparable with the EMPs who recognized 65 out of 67 STEMI patients (97.0%, kappa=0.614). EMTs with more than 1 year of ED work correctly recognized 40 out of 42 STEMI patients (95.2%), and therefore performed better than EMPs, who recognized 39 out of 42 STEMI patients (92.9%, kappa=0.727). The level-1 EMTs adequately recognized STEMI using a 12-lead ECG and were in substantial agreement with the evaluations of the EMPs.

• 복식문화연구
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• 제32권2호
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• pp.232-246
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• 2024

This study examines options to revitalize a B2B textile trading platform, exploring user satisfaction and perceptions of the importance of several website features. Between June 8 and June 21, 2023, fashion studies majors and domestic fashion brand product planners were asked to use the website of an open B2B textile platform for 30 minutes and then evaluate its features by responding to a survey. The final sample for analysis wad comprised of 150 questionnaires. To analyze the key textile website features, a paired t-test, Importance-Performance Analysis (IPA), and multiple regression analysis were utilized. The analysis classified the key textile website features related to user importance and satisfaction into the following categories: convenience, appearance, product information, and uniqueness. An analysis investigation of the differences in importance and satisfaction for each website evaluation attribute found significant differences in 12 attributes. The IPA analysis revealed that attributes such as product reliability, quality, a convenient search function, and convenient page movement are highly important to users and garner high user satisfaction; these findings demonstrate the importance of maintaining these elements. Images on the main screen, the latest trend information, and product prominence attributes also garner high importance ratings, but result in low user satisfaction, which signifies extensive revision is required. Finally, user evaluation of the convenience, appearance, and product information of the website was found to affect user recommendation intention.