• Title/Summary/Keyword: University class model

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A STUDY ON THE STRESS DISTRIBUTION OF CANTILEVER BRIDGE UNDER MAXIMUM BITE FORCE AND FUNCTIONAL BITE FORCE USING THREE DIMENSIONAL FINITE ELEMENT METHOD (최대교합 및 기능교합시 하악구치부 연장가공의치에 발생하는 응력에 대한 삼차원 유한요소법적 연구)

  • Park Chang-Keun;Lee Sun-Hyung;Chung Hun-Young;Yang Jae-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.32 no.4
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    • pp.484-514
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    • 1994
  • Cantilever bridge is widely used by mny clinicians, but its worst mechanical character, so called Class I lever system, makes dentists hesitate to restore the missing tooth with it. Therefore it is important to study stress of the cantilever bridge. In this study, two models of cantilever bridges that restores the missing mandibular second molar with two abutment teeth were constructed. One model was a type of cantilever bridge supported by a normal alveolar bone, the other one was supported by an alveolar bone resorbed to its 1/3 of root length. Maximum bite force(550N) and funtional maximum bite force(300N) were vertically applied to the distal end of the pontic, distal 1/3, and distal half of the pontic. And each force was also applied to centric occlusal contacts as a distributed force. Total 16 loading cases were compared and analyzed with 3-dimensional finite element method. The results were as follows: 1. The stress was concentrated on the joint of the pontic and the retainer, grooves, and distal cervical margin of the posterior retainer. 2. In case of maximum bite force(550N) at the end of the pontic, the risk of fracture at the joint of the pontic and the retainer was high. 3. In case of distributed force in centric occlusion and functional maximum bite force(300N), the stresses were less than the yield strength of the type VI gold for any loading cases. 4. In case of alveolar bone resorption, the occlusal force to the cantilever pontic caused more stress on the root apex and less stress on the alveolar crest region of the distal surface of the posterior abutment. 5. In case of alveolar bone resorption, the displacement was larger than that of normal alveolar bone in all loading cases.

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Growth and Production of Sinonovacula constricta (Bivalvia) from the Hwaseong Tidal Flat in the Namyang Bay, Korea (가리맛조개(Sinonovacula constricta: Bivalvia)의 성장과 생산 (경기 남양만 화성조간대))

  • Koh, Chul-Hwan;Yang, Mee-Ra;Chang, Won-Keun
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.2 no.1
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    • pp.21-30
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    • 1997
  • The present study reports the density, growth and production of a razor clam, Sinollovacula constricta, which is known to be one of the important fishreies catches from the Korean tidal flat. The annual yield reached to about 6,000 metric tons per year till 1994. The study was conducted on the Hwaseong tidal flat located on the central west coast, 40 kilometers south-west from Seoul. The annual yield of the razor clam in this area reached to about 50% of the total catch from the whole Korean coast. Samples were colleted monthly at 14 occasions from May 1992 to August 1993. Density of S. constricta ranged from 92~165 individuals per square meter during the study period. General trend of decreasing density was observed when the animal became older, but an exception was the year class of 1991 whose density was lower than that of 1990. The size of the shell was clearly separated into two classes during fall and winter (from September to February), however, the maximum frequency of the length of small size classes moved to right after February. It indicates a fast growth of young clams from spring to summer. Fast growth of the shell could also be examined by the growth curve. The shell growth of the whole life span was described by the von Bertalanffy equation of $L_t=89.3{\times}[1{\exp}\{-0.58{\times}(t+0.73\}]$. The growth in flesh dry weight was well fitted to the Gompertz growth model with the equation, $W_t=5.00{\times}{\exp}\{-4.31{\times}{\exp}(-0.043{\times}t)\}$. The clam lost about 30% of the body weight during spawning in August. The annual production calculated based on the data from September 1992 to August 1993 amounted to 150 g $DW{\cdot}m^{-2}{\cdot}yr^{-1}$ which was 2~50 fold higher than those of other bivalves occurred in Korea. This estimate was patitioned by each year classes; 87.5 by 1992, 53.4 by 1991, 59.0 by 1990 and -30.0 g $DW{\cdot}m^{-2}{\cdot}yr^{-1}$ by 1989 year class.

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Feasibility of Deep Learning Algorithms for Binary Classification Problems (이진 분류문제에서의 딥러닝 알고리즘의 활용 가능성 평가)

  • Kim, Kitae;Lee, Bomi;Kim, Jong Woo
    • Journal of Intelligence and Information Systems
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    • v.23 no.1
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    • pp.95-108
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    • 2017
  • Recently, AlphaGo which is Bakuk (Go) artificial intelligence program by Google DeepMind, had a huge victory against Lee Sedol. Many people thought that machines would not be able to win a man in Go games because the number of paths to make a one move is more than the number of atoms in the universe unlike chess, but the result was the opposite to what people predicted. After the match, artificial intelligence technology was focused as a core technology of the fourth industrial revolution and attracted attentions from various application domains. Especially, deep learning technique have been attracted as a core artificial intelligence technology used in the AlphaGo algorithm. The deep learning technique is already being applied to many problems. Especially, it shows good performance in image recognition field. In addition, it shows good performance in high dimensional data area such as voice, image and natural language, which was difficult to get good performance using existing machine learning techniques. However, in contrast, it is difficult to find deep leaning researches on traditional business data and structured data analysis. In this study, we tried to find out whether the deep learning techniques have been studied so far can be used not only for the recognition of high dimensional data but also for the binary classification problem of traditional business data analysis such as customer churn analysis, marketing response prediction, and default prediction. And we compare the performance of the deep learning techniques with that of traditional artificial neural network models. The experimental data in the paper is the telemarketing response data of a bank in Portugal. It has input variables such as age, occupation, loan status, and the number of previous telemarketing and has a binary target variable that records whether the customer intends to open an account or not. In this study, to evaluate the possibility of utilization of deep learning algorithms and techniques in binary classification problem, we compared the performance of various models using CNN, LSTM algorithm and dropout, which are widely used algorithms and techniques in deep learning, with that of MLP models which is a traditional artificial neural network model. However, since all the network design alternatives can not be tested due to the nature of the artificial neural network, the experiment was conducted based on restricted settings on the number of hidden layers, the number of neurons in the hidden layer, the number of output data (filters), and the application conditions of the dropout technique. The F1 Score was used to evaluate the performance of models to show how well the models work to classify the interesting class instead of the overall accuracy. The detail methods for applying each deep learning technique in the experiment is as follows. The CNN algorithm is a method that reads adjacent values from a specific value and recognizes the features, but it does not matter how close the distance of each business data field is because each field is usually independent. In this experiment, we set the filter size of the CNN algorithm as the number of fields to learn the whole characteristics of the data at once, and added a hidden layer to make decision based on the additional features. For the model having two LSTM layers, the input direction of the second layer is put in reversed position with first layer in order to reduce the influence from the position of each field. In the case of the dropout technique, we set the neurons to disappear with a probability of 0.5 for each hidden layer. The experimental results show that the predicted model with the highest F1 score was the CNN model using the dropout technique, and the next best model was the MLP model with two hidden layers using the dropout technique. In this study, we were able to get some findings as the experiment had proceeded. First, models using dropout techniques have a slightly more conservative prediction than those without dropout techniques, and it generally shows better performance in classification. Second, CNN models show better classification performance than MLP models. This is interesting because it has shown good performance in binary classification problems which it rarely have been applied to, as well as in the fields where it's effectiveness has been proven. Third, the LSTM algorithm seems to be unsuitable for binary classification problems because the training time is too long compared to the performance improvement. From these results, we can confirm that some of the deep learning algorithms can be applied to solve business binary classification problems.

A case study on the conceptual simulation observed in explanation of elementary school students about the causes of the seasonal change (계절의 변화 원인에 대한 설명에서 나타난 초등학생의 개념 시뮬레이션 사례 연구)

  • Ko, Min-Seok;Kim, Na-Young;Yang, Il-Ho
    • Journal of the Korean Society of Earth Science Education
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    • v.7 no.1
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    • pp.43-53
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    • 2014
  • The purpose of this study is to analyze the conceptual simulation observed when students are thinking about the causes of the seasonal change, identifying how students come up with the explanation. For this study, a framework for conceptual simulation process and strategy based on literary research was developed and its validity was proved by four experts in the field of science education. The results were as in the following: First, through the process of explaining the causes for seasonal change, students usually base their explanation on perceptual experience learned from model experiments from a science class. Besides, construct of thought experiment using the familiar object or analogize of the familiar perceptual experience. These all contributed to on explanation firmly. Second, errors from mental simulation were found in the statement of initial representation and running imagistic simulation. It happened when statement of initial representation is not in a complete and secure state or when participants think of an inappropriate situation during running imagistic simulation. Third, the study identified that the use of strategies like 'removal' and 'replace' was shown to enhance the effects of conceptual simulation particularly in regard with solar attitude at meridian passage.

A Comparative Analysis of Verbal Interaction on Traditional Instruction and Flipped Learning (전통적 수업과 플립러닝 수업의 언어 상호작용 비교 분석)

  • Lee, Heesuk;Heo, Seojeong;Kim, Changsuk
    • Journal of The Korean Association of Information Education
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    • v.19 no.1
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    • pp.113-126
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    • 2015
  • This study intends to investigate the features and the difference between traditional instruction and flipped learning through a comparative analysis of verbal interaction on those learning method. The videos of traditional instruction and flipped learning of 5th graders social class were recorded and transcribed, which were analyzed in Flanders verbal interaction model. The results were as follows: First, the flipped learning is composed of students' learning activity and a teacher's statement properly, while the traditional instruction consists of a teacher's statement mostly. Second, the traditional instruction tends to be directive classes that full of dominant, despotic, restrictive communication of teacher oriented. In contrast, the flipped learning is inclined to be nondirective with integrated, democratic, comprehensive, permissive communication of students oriented. Third, the flipped learning emphasizes students' activities and statement and reduces delivery of knowledge, meanwhile, the traditional instruction stresses delivery of content that the teacher centrally located. Lastly, the type of verbal interaction in traditional instruction is a one-way communication, students responding simply in teacher's lectures and questions. On the other hand, in flipped learning lessons, more interactive communication occurs, teachers complimenting students and accepting their comments.

Development and Application of the Scientific Inquiry-based STEAM Education Program about Earthquakes (지진에 대한 과학 탐구 기반의 STEAM 교육 프로그램 개발과 적용)

  • Lee, Hyundong;Bae, Taeyoun;Lee, Hyonyong
    • Journal of the Korean earth science society
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    • v.37 no.7
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    • pp.476-488
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    • 2016
  • The purposes of this study were to develop a scientific inquiry-based STEAM education program and to investigate its effect on changing middle school students' self-efficacy in science, job awareness, and attitudes toward STEM. A scientific inquiry-based STEAM program was developed with the theme of 'earthquakes', using the ADBA model, which was taking up the total of six class periods. The final program, which had been revised and completed after being pre-tested with middle school students, was implemented to 105 third-graders of middle school in a metropolitan city. One sample pre-post paired t-test before and after applying the program to the same group was conducted, and its effectiveness was analyzed in terms of self-efficacy in science, job awareness, attitudes toward science, technology, engineering and mathematics. Results showed that the STEAM program on the theme of 'earthquakes' demonstrated its effect on improving the students' of self-efficacy in science subject and their awareness of science-related jobs. Furthermore, this program indicated a statistical significance in improving middle school students' attitudes, awareness, and abilities, values, and continuing interest towards science, technology, engineering, and mathematics. Therefore, we suggest that this scientific inquiry based STEAM program be used to help students to improve their scientific investigation skills as well as their creative and integrated thinking abilities in schools.

Characteristic of Buckling and Ultimate Strength of the Perforated Stiffened Plate (유공보강판의 좌굴 및 극한강도 특성에 관한 연구)

  • Park Joo-Shin;Ko Jae-Yong;Oh Kyoung-Gun
    • Journal of Navigation and Port Research
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    • v.30 no.6 s.112
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    • pp.439-446
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    • 2006
  • In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.

Factors Influencing Crash Severity by the Types of Bus Transportation Services Using Ordered Probit Models (순서형 프로빗 모형을 이용한 버스 운송사업 유형 별 사고심각도 영향요인 분석)

  • YOON, Sangwon;KHO, Seung-Young;KIM, Dong-Kyu
    • Journal of Korean Society of Transportation
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    • v.36 no.1
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    • pp.13-22
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    • 2018
  • Buses, one of the representative public transportation modes, are divided into a vareity of service types according to the purpose of operation, operating distance, and management agencies. Although bus-involved crashes may cause large amount of damage due to the higher number of passengers boarded on a bus, prior research has little focused on crash severity according to bus service types. This study aims to investigate factors influencing crash severity in bus-involved crashes and to present policy implications to reduce crash severity by bus service type. To do this, bus-involved crash data from the Traffic Accident Analysis System (TAAS) during five-year period are used. Ordered probit models for three types of bus service, i.e., city bus, suburban and express buses, and charter buses, are estimated to analyze the factors of accident severity. The results show that there are significant differences of factors affecting crash severity among the types of bus services while speed and road surface influence all the types of buses. In case of local buses, time of day, roadway alignment, and installation of a traffic signal are found to be statistically significant factors. Seat belt and road class have significant effects on injury severity of the intercity and express buses. Chartered buses have time of day, driving experience, seatbelt, traffic signal, and day of week as the significant factors. The results of this study are expected to contribute to the reduction of the crash severity by each bus service type.

Development of Educational Program of STEAM-based Project for Circle Activities in Middle School: Focused on the Theme of "Photography of Earth" (중학교 동아리활동을 위한 STEAM 기반 프로젝트 교육 프로그램 개발: '지구사진 촬영' 주제를 중심으로)

  • Kim, Hyun-Jung;Kim, Young-Min;Kim, Jin-Yeon;Huh, Hye-Yeon;Kim, Jong-Nam;Kim, Ki-Soo
    • 대한공업교육학회지
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    • v.38 no.2
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    • pp.195-217
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    • 2013
  • The purpose of this study was to develop educational programs of STEAM-based project under the theme of "Photography of Earth" for the circle activities of the creative experiential activity, to be applied this program to them and to identify technology subject self-efficacy and change in attitude toward engineering. In order to achieve the research objectives, this program was applied to middle school student in Cheonan, STEAM-based circle during 9 class instruction. The results of this study are as follows. First, the STEAM program contents for circle activities were selected through utilizing a five-stage design model(preparation, design, development, implementation and evaluation) and analyzing the curriculum. After that we have developed a teaching plan, STEAM-Story, student activity sheets from the viewpoint of cultural fusion and have applied the circle activities of the creative experiential Activity during 4 months. Second, The result of the test(pre- and post-test) about STEAM program that has been developed were different about technology subject self-efficacy and attitude toward engineering. Therefore, we have verified that the effect of the STEAM-based project under the theme of "Photography of Earth" for the circle activities on the attitudes toward engineering and self-efficacy in middle school is effective.

A Study on Improvement through Functionality Evaluation on Botanic Gardens and Arboreta in Korea (식물원·수목원 기능성 평가를 통한 개선방안 연구)

  • Kang, Hyun Kyung;Kim, Sun Hae;Kweon, Min-Hoon;Bang, Kwang Ja;Kim, Kwang Doo
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.15 no.3
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    • pp.29-43
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    • 2012
  • This study evaluated 23 botanic gardens and arboretums under two main categories including professional group and operational group. As for professional group, the main difference between the functions of botanic gardens and arboretums was analyzed. In the case of operational group compared professional group respectively, on categories including importance of function and implementation, seeking to provide fundamental data of botanic gardens and arboretums by enhancing the quality of visitors and examining functional differences. The result of a difference in arboretums' function between professional and operational groups, the study analyzed the importance of botanic gardens and arboretums in terms of detailed categories such as research, education, collection, display, retention, and service for visitors. As a result, professional group showed retention 4.32>education 4.11>research 4.09>service for visitors 4.05, and operational group showed retention 3.70>service 3.52>education 3.41>research 3.37, indicating that both groups had retention as the most selected answer. Looking closely at the functions of the currently implemented detailed categories of botanic gardens and arboretums, such as research, education, collection, display, retention, and service for visitors, the study showed that 91.3% selected rare species and individual multiplication for research function, 78.3% chose education of natural ecosystem for children for education, 73.9% answered space for experiencing nature for display, and 73.9% also replied managon, diof rare species, reproduction, and retention of native plants' species for retention category, and service for visitors showed 95.7% for implementation. The study could not clearly point out the influence between predictors due to absence of an established comprehensive evaluation model. Also, it analyzed and reviewed comparison of functions of professional group and operational group, but in the future, it should conduct study on a systemic and objective classification of botanic gardens and arboretums to clearly examine the difference in views between groups, which also requires, at the same time, study on management policy of botanic gardens and arboretums or suggesting guidelines that suit types of forms, and also study on facilities and program development that can be applied to each class.