• Title/Summary/Keyword: Evaluation Models

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Features in Pre-Service Teachers' Reflective Discussion on their Practical Work-Based Teaching (예비교사의 실험 수업에 대한 반성적 논의의 특징)

  • Shim, Hyeon-Pyo;Ryu, Kum-Bok;Lee, Eun-Jeong;Jeon, Sang-Hak;Hwang, Seyoung
    • Journal of The Korean Association For Science Education
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    • v.33 no.5
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    • pp.911-931
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    • 2013
  • The purpose of this study was to analyze pre-service teachers' reflective discussion on their practical work-based teaching by focusing on the components of instruction and the connectivity of discussion. Eight after-class discussions were recorded and transcribed, and finally analyzed in terms of theoretically driven categories such as aims, teacher knowledge and learner response which also respectively reflect the actual flow of planning, implementation and evaluation of the teaching practice. The result showed that in their discussion about students, conceptual understanding and scientific skill components were most emphasized, while teaching method and strategy were most frequently addressed in the discussion about teacher knowledge. But this also revealed problems in their discussions such as the lack of discussion about inquiry and student interest, difficulties in clarifying theoretical terms and the lack of discussion about instructional models and theories. Meanwhile, pre-service teachers' discussions were limited in terms of connectivity between the components of instruction, meaning that their discussion tended to deal with each component separately rather than occurred in connection with each other. Furthermore, when connections were made during the discussion, only few components of instruction appeared. Based on this result, the paper suggests the need to develop tools to facilitate effective reflection in ways that incorporate various components of instruction and enhance connectivity between the components and between the instructions.

Local Correction of Tree Volume Equation for Larix leptolepis by Ratio-of-Means Estimator (평균비(平均比) 추정량(推定量)에 의한 낙엽송(落葉松) 입목(立木) 재적식(材積式)의 지역(地域) 보정(補正))

  • Shin, Man Yong;Yun, Jong Wha;Cha, Du Song
    • Journal of Korean Society of Forest Science
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    • v.85 no.1
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    • pp.56-65
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    • 1996
  • Current volume tables might underestimate or overestimate the volumes of individual trees in a specific region because the tables were made using the data from broad region. This study provides a statistical method of local correction, which is the ratio-of-means estimator, when the table is applied to the data from a specific region. Data used in this study were 411 trees of Larix leptolepis from Hongchon region. Five statistical models for individual tree volume equation were evaluated based on 3 evalation criteria and the best equation fitted to the data from Hongchon region was selected. The volume estimated by the selected equation was then compared with the volume estimated by the current volume table. From the ratio-of-means estimate based on the volumes estimated by selected equation and by current volume table, the local correction was made. The correction equation was $V_{Hongchon}=1.078$ $V_{volume\;table}$. It is also proved that the correction equation can simply and precisely estimate tree volumes of Larix leptolepis in Hongchon region using the current volume table.

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A COMPARATIVE STUDY ON THE ACCURACY OF PREDICTION METHODS OF UNERUPTED CANINE AND PREMOLARS IN THE MIXED DENTITION (미맹출 영구치 폭경예측방법의 정확도에 관한 비교연구)

  • Lee, Eun-Young;Choi, Yeong-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.23 no.4
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    • pp.788-799
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    • 1996
  • The purpose of this study was to determine the accuracy of the prediction methods which are frequently used in the clinic, such as Moyers', Tanaka and Johnston's, Song's Hixon and Oldfather's, Kaplan's, Smith's. These prediction methods were compared to the data, which were obtained from 100 Kyung-Hee University students (50 males and 50 females) with normal occlusion of permanent dentition, using a retrospective statistical analysis. The standard periapical radiopgraphs for the lower premolars using 16-inch long cone technique and the yellow stone dental casts were taken from each samples. The mesiodistal widths of 4 incisors, canine, premolars were measured on the dental casts, and those of premolars were measured on the radiographs. The correlation coefficients, paired samples t-tests, regression coefficients between the actual measuredments of the samples and the predicted measurements of each methods were analyzed. The results obtained were as follows: 1. The prediction methods using periapical radiographs tended to show a stronger correlation than the methods using dental casts; the correlation coefficients between the actual widths of the lower canine and premolars and the predicted widths of the tested methods were higher in Smith, Kaplan, Hixon & Oldfater, and Tanaka & Johnston (p<0.001). 2. The Moyers' probability chart at 65 % showed a tendency toward the least difference between the actual measurements and the predicted widths of the lower canine and the premolars, and the methods of Smith, Kaplan, Tanaka & Johnston also showed a less difference. 3. By means of evaluation in correlation coefficients and paired smaples t-tests, the Smith and Tanaka & Johnston in male, and the Moyers' 65 % and Song in female showed a high tendency toward accurate methods. 4. The regression equations by models that are derived from the study were as follows: Male(Lt.) :Y=10.799+0.475X Femle(Lt.) :Y= 7.427+0.609X (Rt.) :Y=11.043+0.462X (Rt.) :Y= 8.475+0.556X 5. The regression equations by radiographs that are dericed from the study were as follows: Male(Lt.) :Y=6.5651+0.9720X Femle(Lt.) :Y=4.8656+1.0632X (Rt.) :Y=7.8610+0.9060X (Rt.) :Y=4.5483+1.0843X

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Evaluation of Compaction and Thermal Characteristics of Recycled Aggregates for Backfilling Power Transmission Pipeline (송배전관로 되메움재로 활용하기 위한 국내 순환골재의 다짐 및 열적 특성 평가)

  • Wi, Ji-Hae;Hong, Sung-Yun;Lee, Dae-Soo;Park, Sang-Woo;Choi, Hang-Seok
    • Journal of the Korean Geotechnical Society
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    • v.27 no.7
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    • pp.17-33
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    • 2011
  • Recently, the utilization of recycled aggregates for backfilling a power transmission pipeline trench has been considered due to the issues of eco-friendly construction and a lack of natural aggregate resource. It is important to identify the physical and thermal properties of domestic recycled aggregates that can be used as a backfill material. This paper evaluated thermal properties of concrete-based recycled aggregates with various particle size distributions. The thermal properties of the recycled aggregates and river sand provided by local vendors were measured using the transient hot wire method and the transient needle probe method after performing the standard compaction test. The needle probe method considerably overestimated the thermal resistivity of recycled aggregates especially at the dry of optimum water content because of experiencing disturbance while the needle probe is being inserted into the specimen. Similar to silica sand, the thermal resistivity of recycled aggregates decreased when the water content increased at a given dry density. Also, this paper evaluated some of the existing prediction models for the thermal resistivity of recycled aggregates with the experimental data, and developed a new prediction model for recycled aggregates. This study shows that recycled aggregates can be a promising backfill material substituting for natural aggregates when backfilling the power transmission pipeline trench.

An RDB to RDF Mapping System Considering Semantic Relations of RDB Components (관계형 데이터베이스 구성 요소의 의미 관계를 고려한 RDB to RDF 매핑 시스템)

  • Sung, Hajung;Gim, Jangwon;Lee, Sukhoon;Baik, Doo-Kwon
    • KIPS Transactions on Software and Data Engineering
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    • v.3 no.1
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    • pp.19-30
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    • 2014
  • For the expansion of the Semantic Web, studies in converting the data stored in the relational database into the ontology are actively in process. Such studies mainly use an RDB to RDF mapping model, the model to map relational database components to RDF components. However, pre-proposed mapping models have got different expression modes and these damage the accessibility and reusability of the users. As a consequence, the necessity of the standardized mapping language was raised and the W3C suggested the R2RML as the standard mapping language for the RDB to RDF model. The R2RML has a characteristic that converts only the relational database schema data to RDF. For the same reasons above, the ontology about the relation data between table name and column name of the relational database cannot be added. In this paper, we propose an RDB to RDF mapping system considering semantic relations of RDB components in order to solve the above issue. The proposed system generates the mapping data by adding the RDFS attribute data into the schema data defined by the R2RML in the relational database. This mapping data converts the data stored in the relational database into RDF which includes the RDFS attribute data. In this paper, we implement the proposed system as a Java-based prototype, perform the experiment which converts the data stored in the relational database into RDF for the comparison evaluation purpose and compare the results against D2RQ, RDBToOnto and Morph. The proposed system expresses semantic relations which has richer converted ontology than any other studies and shows the best performance in data conversion time.

On the Use of Modal Derivatives for Reduced Order Modeling of a Geometrically Nonlinear Beam (모드 미분을 이용한 기하비선형 보의 축소 모델)

  • Jeong, Yong-Min;Kim, Jun-Sik
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.4
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    • pp.329-334
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    • 2017
  • The structures, which are made up with the huge number of degrees-of-freedom and the assembly of substructures, have a great complexity. In order to increase the computational efficiency, the analysis models have to be simplified. Many substructuring techniques have been developed to simplify large-scale engineering problems. The techniques are very powerful for solving nonlinear problems which require many iterative calculations. In this paper, a modal derivatives-based model order reduction method, which is able to capture the stretching-bending coupling behavior in geometrically nonlinear systems, is adopted and investigated for its performance evaluation. The quadratic terms in nonlinear beam theory, such as Green-Lagrange strains, can be explained by the modal derivatives. They can be obtained by taking the modal directional derivatives of eigenmodes and form the second order terms of modal reduction basis. The method proposed is then applied to a co-rotational finite element formulation that is well-suited for geometrically nonlinear problems. Numerical results reveal that the end-shortening effect is very important, in which a conventional modal reduction method does not work unless the full model is used. It is demonstrated that the modal derivative approach yields the best compromised result and is very promising for substructuring large-scale geometrically nonlinear problems.

Evaluation of Seismic Behavior for RC Moment Resisting Frame with Masonry Infill Walls (비내력벽을 가진 RC모멘트저항골조의 지진거동 평가)

  • Ko, Hyun;Kim, Hyun-Su;Park, Yong-Koo;Lee, Dong-Guen
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.5
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    • pp.13-22
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    • 2010
  • Masonry infill walls are frequently used as interior partitions and exterior walls in low- or middle- rise RC buildings. In the design and assessment of buildings, the infill walls are usually treated as non-structural elements and they are ignored in analytical models because they are assumed to be beneficial to the structural responses. Therefore, their influences on the structural response are ignored. In the case of buildings constructed in the USA in highly seismic regions, infill walls have a lower strength and stiffness than the boundary frames or they are separated from the boundary frames. Thus, the previously mentioned assumptions may be reasonable. However, these systems are not usually employed in most other countries. Therefore, the differences in the seismic behaviors of RC buildings with/without masonry infill walls, which are ignored in structural design, need to be investigated. In this study, structural analyses were performed for a masonry infilled low-rise RC moment-resisting frame. The infill walls were modeled as equivalent diagonal struts. The seismic behaviors of the RC moment-resisting frame with/without masonry infill walls were evaluated. From the analytical results, masonry infill walls can increase the global strength and stiffness of a structure. Consequently, the interstory drift ratio will decrease but seismic forces applied to the structure will increase more than the design seismic load because the natural period of the structure decreases. Partial damage of the infill walls by the floor causes vertical irregularity of the strength and stiffness.

Design Guidelines of Road Cross Sectional Elements Based on the Satisfaction of Sensibility Cognition (감성인지 만족도를 고려한 도로횡단면 구조설계 기준 연구)

  • Seo, Im Ki;Lee, Byung Joo;Lee, Jae Sun;Namgung, Moon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3D
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    • pp.363-373
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    • 2011
  • With rapid economic development, general demand and interest in surroundings that consist of our lives have grown gradually. In addition, as there has been increased social interest in creating landscape of roads, which considers all important factors from the user's view including accessibility, safety, and psychological stability, efforts to improve quality of roads are required. Therefore it is needed to establish standards on safe and comfort road design based on sensibility satisfaction of road users rather than based on standardized road design guidance from the engineering perspective. To this end, research was carried out to analyze sensibility satisfaction of users about road landscape focused on elements of road cross section in a city. It identified relation between sensibility satisfaction and the elements by using principal and cluster analysis, and the multiple regression models. It also found that user's satisfaction about roads and a road landscape is high with road width (3~5 meters), clear zone (2.2~3.9 meters), road central garden (1.05~1.9 meters), shoulder (0.55~1.43 meters), median (0.65~1.625 meters), the number of travel lanes (2~5), height of trees at the central garden (6.4~15 meters) and height of buildings surrounding roads (18~44 meters or 6~15 floors).

Evaluation of Long-Term Deformation Prediction Model on Frozen Sand Considering Fine Contents (세립분 함량을 고려한 동결 사질토의 장기변형 예측 모델 평가)

  • Hwang, Bumsik;Chae, Deokho;Cho, Wanjei
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.37 no.1
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    • pp.93-103
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    • 2017
  • Many countries are interested in the development of the Antarctic area because of the abundant resources and living things of high research value. Korea completed the second Antarctic research station in 2014 and spurring the development of the Antarctic area by constructing runway for the airplanes and a third Antarctic research station. However, frozen soils, unlike typical soils, are sensitive to creep behavior due to the influence of ice and unfrozen water. The creep tests for evaluating creep behaviors on the frozen soils require expensive laboratory equipments and large amount of time. Thus, various empirical models had been developed to describe the unconfined compressive creep behavior of frozen soils. In this study, new analytical creep model on frozen sands was proposed by modifying Ting's Tertiary creep model with a new parameter considering fine contents. Thus, the unconfined compressive creep tests were conducted with the frozen specimens of dense Jumoonjin sand with fine contents of 0, 5, 10 and 15% under various loads at -$5^{\circ}C$, -$10^{\circ}C$ and -$15^{\circ}C$. Consequently, the modified Tertiary creep model with a new parameter for fine contents are not enough for the description of the acutal creep behavior of the frozen sand and new framework should be developed.

Quantitative Analysis of Port Incentive Effect: Focusing on Busan Port (항만인센티브제도의 효과에 대한 정량적 분석: 부산항을 중심으로)

  • Ha, Myung-Sin;Kim, Chul-Min;Chang, Byoung-Ky
    • Journal of Korea Port Economic Association
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    • v.27 no.2
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    • pp.355-372
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    • 2011
  • Various incentive policies for transshipment cargo have been enforced without any evaluation of the effectiveness. Therefore, the purpose of this study is to evaluate the effect of volume incentive on container transshipment cargo. To be different from previous studies, this study tries to quantitatively assess the incentive effects by using econometric techniques. The result derived from the ARIMA type models indicates that the total amount of the increased transshipment cargo during the last 7 years is about one million TEU. In the meanwhile, the multivariate long run equilibrium model implies that the increased transshipment cargo is less than 0.5 million TEU for the 7 years. Furthermore, the structural break tests indicate that the volume incentive does not change the model structures. It means that the effect of volume incentive is not statistically significant. Consequently, the test results conclude the effect of volume incentive on transshipment cargo is not significant although the volume of transshipment cargo is increased to some extent by volume incentive. Considering the magnitude of BPA's expenditure, we doubt the effectiveness of volume incentive. This study, therefore, encourages the port authority to research a more efficient way to induce transshipment cargo rather than focusing on only volume incentives.