PURPOSES : To enhance the accuracy of predicting the compressive strength of practical concrete mixtures, this study aimed to develop a machine learning model by utilizing the most commonly employed curing age, specifically, the 28-day curing period. The training dataset consisted of concrete mixture sample data at this curing age, along with samples subjected to a total load not exceeding 2,350 kg. The objective was to train a machine learning model to create a more practical predictive model suitable for real-world applications. METHODS : Three machine learning models—random forest, gradient boosting, and AdaBoost—were selected. Subsequently, the prepared dataset was used to train the selected models. Model 1 was trained using concrete sample data from the 28th curing day, followed by a comprehensive analysis of the results. For Model 2, training was conducted using data from the 28th day of curing, focusing specifically on instances where the total load was 2,350 kg or less. The results were systematically analyzed to determine the most suitable machine learning model for predicting the compressive strength of concrete. RESULTS : The machine learning model trained on concrete sample data from the 28th day of curing with a total weight of 2,350 kg or less exhibited higher accuracy than the model trained on weight-unrestricted data from the 28th day of curing. The models were evaluated in terms of accuracy, with the gradient boosting, AdaBoost, and random forest models demonstrating high accuracy, in that order. CONCLUSIONS : Machine learning models trained using concrete mix data based on practical and real-world scenarios demonstrated a higher accuracy than models trained on impractical concrete mix data. This case illustrates the significance of not only the quantity but also the quality of the data during the machine learning training process. Excluding outliers from the data appears to result in better accuracy for machine learning models. This underscores the importance of using high-quality and practical mixed concrete data for reliable and accurate model training.

환경시설물, 댐과 같은 유체를 저장하는 시설물을 대상으로 엄밀하게 지진 거동을 평가하기 위해서는 유체-구조물 상호작용을 고 려한 해석이 필요하다. 특히, 댐-호소 계와 같이 상류 방향으로 무한 영역을 가지는 경우에는 이를 적절히 고려해야 할 필요가 있다. 본 연구에서는 댐-호소 계와 같은 반무한 유체 영역을 갖는 시스템을 대상으로 무한 영역의 파전파 해석 및 유체-구조물 상호작용 해석을 위한 실용적인 수치 모형을 제시하였다. 시간영역에 적용가능한 방법으로 정확하면서도 경계적인 해석이 가능하다. 무한 유체 영역 에 대해서는 일반 acoustic finite element 대신 작은 개수의 mid-point integrated acoustic finite element를 적용하고 최종 경계에는 점성 경계를 부과한다. 제안하는 방법의 유효성과 정확성을 검증하기 위해 강체 댐체를 가정한 반무한 호소계를 대상으로 적용하는 요소 의 개수, 모델링 영역 크기 등을 매개변수로 해석해와 비교·검증하였다. 제안된 방법을 적용하여 댐-호소 계의 유체-구조물 상호작용 을 부가질량을 사용하는 경우와 비교하였다.

Although retailers deals with a large number of single-term inventory items, but few cases have been considered in the areas of practical decision making. However, recent moves to strengthen fair trade have created a real need for single-period inventory decision-making problems. This study addresses the problem of ordering quantity decisions that are expected to maximize profits using classical newsvendor models. The research target is data on seasonal and perishable products from retail. We also use data from retailers to actually apply the newsvendor model and calculate the results to compare performance. It also suggests solutions for estimating demand for products sold in order to apply newsvendor models that utilize actual demand ratio versus forecast demand. This study would like to examine the effectiveness of this research through data analysis and make some suggestions for applying it to reality.

In this study, a numerical approach based on mid-point integrated finite elements and a viscous boundary is proposed for time-domain wave-propagation analyses in infinite poroelastic media. The proposed approach is accurate, efficient, and easy to implement in time-domain analyses. In the approach, an infinite domain is truncated at some distance. The truncated domain is represented by mid-point integrated finite elements with real element-lengths and a viscous boundary is attached to the end of the domain. Given that the dynamic behaviors of the proposed model can be expressed in terms of mass, damping, and stiffness matrices only, it can be implemented easily in the displacement-based finite-element formulation. No convolutional operations are required for time-domain calculations because the coefficient matrices are constant. The proposed numerical approach is applied to typical wave-propagation and soil-structure interaction problems. The model is verified to produce accurate and stable results. It is demonstrated that the numerical approach can be applied successfully to nonlinear soil-structure interaction problems.

The β-transus temperature in titanium alloys plays an important role in the design of thermo-mechanical treatments. It primarily depends on the chemical composition of the alloy and the relationship between them is non-linear and complex. Considering these relationships is difficult using mathematical equations. A feed-forward neural-network model with a back-propagation algorithm was developed to simulate the relationship between the β-transus temperature of titanium alloys, and the alloying elements. The input parameters to the model consisted of the nine alloying elements (i.e., Al, Cr, Fe, Mo, Sn, Si, V, Zr, and O), whereas the model output is the β-transus temperature. The model developed was then used to predict the β-transus temperature for different elemental combinations. Sensitivity analysis was performed on a trained neural-network model to study the effect of alloying elements on the β-transus temperature, keeping other elements constant. Very good performance of the model was achieved with previously unseen experimental data. Some explanation of the predicted results from the metallurgical point of view is given. The graphical-user-interface developed for the model should be very useful to researchers and in industry for designing the thermo-mechanical treatment of titanium alloys.

One of major education process flaws in the Lembaga Pendidikan Tenaga Kependidikan (LPTK) or Teacher Training Institute in Indonesia is portrayed in the implementation of the Program Pengalaman Lapangan (PPL) or Apprentice Program that has not optimally developed candidate’s proficiency to be competent teachers. Therefore, this research is intended to construct a teaching and learning model of practical teaching that can improve pedagogical competence as the ultimate goal to be achieved by future teacher candidates. The main subjects of this study were undergraduate students of the Elementary School Teacher Education program conducting their PPL in Indonesia University of Education and Lampung University. Based on the analysis of Wilcoxon Signed Rank Test, on the level of significance of 95% (α = 0,05), the model produced from the research and development process and called theModel Pembelajaran Praktik Mengajar Reflektif (MP2MR) was verified to help improve students competence based on the following benefits,(a) teaching and learning and evaluation designs focused on standardized achievements (b) individual and contextual implementation of problem-solving based process of teaching and learning, and (c) priority to intrinsic evaluation.

이 논문은 “소요 오일붐 측정프로그램(OBM Program)”을 실행함에 따라 발생할 수 있는 문제점을 분석하고자 한다. OBM Program 운용상 한계를 분석하기 위해 운용자와 운용환경 팩터 간의 관계 분석이 가능한 M-SHEL모델을 이용했다. M-SHEL 모델분석을 통해 얻은 결 과는 첫째, 운용자의 입력 값의 신뢰도 향상을 위해 감지 시스템 구축, 둘째, 운용자의 프로그램 사용시 운용에 대한 이해도 향상을 위한 실용적 이고 편리한 매뉴얼 제작, 셋째, 시각화된 프로그램 프레임 구축이다. 분석을 통해 프로그램 운용상의 한계를 보완함으로써 보다 개선된 성능과 더불어 효율적인 방제활동에 기인할 것으로 기대된다.

This study is to focus on the contribution and application in practical models for aging welfare mission in Korea. The number of aging peoples has so rapidly increased from 2000s. This apparence has service some important as the aging welfare of the Korean is being considered. The practical models for aging welfare mission are very significant sphere of social welfare mission. This article is analyzed models and practices for aging welfare through social service in the church community. The church should be realize the missional direction toward the social responsibility. The church can also provide service not only spiritual needs but also social needs toward the aging poor peoples. By doing this way, the church and government can support together hand in hand to achieve better environment for spiritual and physical living. For this aging welfare mission, I want to recommend several suggestions to the church. Firstly, we can be recognize mission of aging welfare to church community. We should be understand that the church must practice important social responsibility for social welfare. Secondly, We need a networking and partnership among the church, NGO, and government for social service. Finally, We can use materially, financially, culturally practical resources in the church toward aging welfare mission. We need flexible strategy and plan in various missional direction for development of aging welfare mission in Korea society.

This study was conducted to effectively develop rural tourism in Korea. For the purpose, tourism that can develop with local industries and cultures together was designated as life-type tourism and development models of such tourism were reviewed based on an understanding that province-oriented tourism is necessary. An analysis of three actual cases of Japan led to following results. First, life-type tourist destinations can be developed in connection with making local areas based on their special themes, can be developed in relation to their life cultures based on their peculiar life cultures and can be developed in creative forms using characteristic environment and organizational culture of those areas. In pursuing life-type tourist attractions, it will be possible to make practical development using it with those three basic models. Second, it is important to form a flow covering the entire regions based on their own special themes, to build cyclical structure of regions and tourism and tourism and industries and to create overall conditions that can help local residents get benefits and join together, in order to develop such life-type tourist destinations. Development of life-type resort tourist destinations needs roles of practical organizations that can effectively manage them, but such organizations should be dynamic and should be distant from management of money as much as possible.

본 논문은 산업체에서 활용 가능한 업무 중심의 내용을 기반으로 산학협동에 의한 교육 실습사례 연구를 통해서 '산학협동 개념 모델'을 제안하였다. 제안 모델의 형태를 단계적 프로세스로 표현하기 위해서 게임 제작에 대한 전체 실습 과정을 '산학협동 파이프라인(Pipe-line)'으로 구성하였고 이에 관한 단계별 사례 내용을 기술하였다. 본 논문의 연구목적은 일반적인 산업체와의 산학협동 과정에서 벗어나 실제 학습하는 대상자에게 산업 현장의 제작 프로세스를 직 간접적으로 체험시키는데 중점을 두었으며, 무엇보다도 해당 실습 교수자의 단계별 역할 중요성을 제시하는 산학협동 모델의 제안이다. 이는 향후, 산학협동 관련 교육 실습 및 관련 연구의 참고자료로서 활용 될 수 있다.

일반적으로 상선에서 해상운송 사고의 주된 원인은 원의 인적과실로 고려되고 있다. 본 논문에서는 선박에 승선 중인 선장, 1항사, 2항사 및 3항사를 포함하는 갑판사관들이 야기할 수 있는 사고 위기를 평가하기 위한 인적과실 모델(HEM)의 구축기법에 관해서 기술했다. 연구범위는 130척의 선박을 관리하는 회사에 소속된 542명의 갑판사관들을 대상으로 했다. 우선, 갑판사관들의 인적 데이터에 대한 통계적 분석과 전문가에 의한 브레인스토밍 과정을 통해서 KEM을 구축하고, 인적과실을 평가하기 위한 인적요소들의 변수 r와 r에 대한 평가등급 EP(r) 및 가중치 α, 갑판사관의 직책별 가중치 β 등을 결정했다. 그리고 선박의 사고기록에 대한 통계분석 결과, 인적과실에 의한 사고원인 비율 γH와 외적과실에 의한 사고원인 비율 γB은 0.517(51.7%)과 0.483(48.3%)로 나타났다. r의 상관계수는 95%(p 〈 0.05) 신뢰구간에서 유의함을 확인하였고, 각 갑판사관의 위기수준 RL의 정규 확률분포 분석으로부터 HEM의 타당성을 검토했다.

생애주기비용을 고려한 교량의 설계 및 유지관리에 있어서, 점검진단, 보수보강 등에 소요되는 직접적인 비용뿐만 아니라 간접적인 비용인 도로이용자비용은 중요한 비용항목으로 고려되고 있다. 직접비용과 비교하여 상대적으로 추정이 곤란한 도로이용자비용의 추정을 위하여 우회도로의 효과를 고려한 이용자지연비용과 차량운행비용의 정식화를 수행하고, 시간지체에 따른 도로이용자비용의 추정을 위한 회귀모델 개발을 위하여 교통해석과 회귀분석을 수행하였다. 개발된 회귀모델을 생애주기 비용 및 성능 기반 유지관리 전략 수립에 적용하여 도로이용자비용이 생애주기분석에 미치는 영향을 분석하고, 개발된 모델의 적용성에 대해서 고찰하였다. 도로이용자비용은 생애주기분석에 기초한 유지관리전략수립에 큰 영향을 미치며, 개발된 회귀모델은 교량의 도로이용자비용의 추정에 실용적으로 활용될 수 있을 것으로 판단된다.