• The Mathematical Education
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• v.57 no.2
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• pp.75-92
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• 2018

Based on Perceptions about Mathematics Teachers (PMT) perceived by high school students, measured by 2189 students from Seoul Educational Longitudinal Study 2014 (SELS 2014), latent profile analysis (LPA) identified five distinct types of student groups (positive, partial positive, middle, negative, extreme negative). These student of positive, middle, and negative groups are positive, moderate and negative perceptions about math teachers. Partial positive group generally had a positive perception about mathematics teachers, extremely negative group was very negative about mathematics teachers. Both of these groups had peculiarly inconsistent trends and several anomalies. The Multinomial logistic regression analyses also indicated that individual factors (gender, major, self-concept, resilience, self-assessment, career maturity), school factors (friendship, relationship with school teachers) and parental factors (academic-relationship, emotional-relationship) were significant predictors of PMT profile groups. The Analysis of variance also indicated that mathematics class (attitude, satisfaction and atmosphere), Mathematics achievement were significant predictors of PMT profile groups. The profiling of perceptions about mathematics teachers resulted in enhanced understanding of the complex range of processes students employed. During mathematics class, implementation of smooth interactions and communications between students and teachers added in the teaching and learning of mathematics.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.1
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• pp.73-86
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• 1997

This study was performed to assess the analyzing methods developed to detect clinically and quantitatively longitudinal bone changes. Through preliminary experiment, accuracy of Cu-Eq value conversion to the mass of HA was examined. For main experiment, 15 intraoral radiograms taken at soon, 1st, 2nd, 4th, and 6th week after implantation of mixture in extracted sites of 3 cases were used. We took the radiograms with copper step wedge as test object and HA phantom X -ray taking was standardized by using Rinn XCP device customized directly to the individual dentition with resin bite block. The images inputted by Quick scanner into computer were digitized and analyzed by NIH image program. The stability of the copper equivalent transformation and the usefulness of two analyzing methods by ROI and Reslice were examined. Obtained results as follows: 1) On the Cu equivalent images, the coefficient of variation in the measurement of Cu-Eq. value of ROI ranged from 0.05 to 0.24 and showed high reproducibility. 2) All results obtained by resliced contiguous image were coincident with those obtained from the assessment by ROI and formation of plot profile. 3) On the stacked and resliced image at the line of interest, we could analyze directly and quantitatively the longitudinal changes at several portions by plot profile and qualitatively by surface plot. 4) Implant area showed marked resorption till 2 weeks after implantation and showed significant increase in Cu-Eq. value at 6th week(p<0.01) and periapical area showed increase in Cu-Eq. value at 6th week compared to after-operation's.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.7-20
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• 1989

A serial cephalometric study was undertaken to define the growth of the soft tissue facial profile in Korean children. The sample was composed of 25 males and 15 females for whom yearly cephalometric records were taken from the ages of 6 to 13 years. From the tracings, points on skeletal and soft tissue profiles were located and recorded on magnetic tape utilizing a Calcomp Talos RP660 X-Y digitizer. Linear and angular measurements of soft tissues were made directly from tape in a Cyber 174-16 computer after cephalometric enlargement had been corrected. A statistical evaluation was made of the data and the average profile diagrams in male and female were described by a Calcomp 960 pen plotter. On the basis of the findings of this study, the following trends were established. 1. The most prominent growth in soft tissue facial profile thickness was the nose and the least was the forehead. 2. The general growth direction of the soft facial tissue to the cranium described the downward and forward. 3. The degree of soft tissue facial convexity was decidely more than that exhibited earlier in life even though the soft tissue chin had protruded to the cranium. 4. The measurements indicated a general tendency for males to have larger nose and more convex and long soft tissue facial profile than did females. 5. Males showed significantly more growth than females in base of the upper lip and height of the upper anterior facial profile. 6. There was a difference between males and females in the rates of soft tissue facial profile growth. 7. Korean children showed less convex in the soft tissue profile convexity than did American children.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.593-601
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• 1999

The knowledge about structure of the velocity in the stream IS essential in the investigation of stream meandering, erosion and sediment transport, and dispersion of pollutants in the stream. In this study, theoretical velocity profile model in which transverse profile of the longitudinal velocity in the stream can be predicted using stream hydraulic data was developed. The proposed model was tested with the measured velocity data of the Nakdong river. The result shows that the numerical model simulates properly the general shalxc of the measured velocity profiles. The simulated profiles agree well with measurements, especially in the aspects of skewness and flatness.atness.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.19-24
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• 2000

Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.122-131
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• 2015

Recently, starting with the deep underground road construction plan in Seobu Expressway, Korea, there area many studies on deep underground roads to be newly built. However, there is an extreme lack of safety standards, which does not consider traffic conditions and road driving characteristics. Therefore, this study reviewed safety elements to reflect in the deep underground road planning by analyzing driving stability of longitudinal tunnels with road environments, which resemble deep underground roads. For comprehensive analysis, the characteristics and causes of the accidents that have occurred in seven longitudinal tunnels with a length of 2km or over in Gangwon area, were collected. Specifically, geometric structures and facilities of each tunnel were investigated. Also, the present state of facility installation and the changes in driving speed of vehicles passing through each tunnel were observed to analyze the causes for the traffic accidents in each tunnel and accident reduction alternatives. It was revealed that the most frequent accidents in the tunnels resulted from the changes of traffic flow due to the abrupt speed reduction of forward vehicles, or the failure in speed control of following vehicles during the traffic congestion situation. Moreover, installing facilities such as plane and longitudinal curves, median strips and marginal strips seem to induce consistent driving speed. These results mean that for accident prevention, speed management must be preceded and there is a need to develop and introduce safety facilities actively to control the driving flow of forward and following vehicles.

• Journal of the Korean Geographical Society
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• v.39 no.5 s.104
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• pp.722-734
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• 2004

Longitudinal profiles of bedrock rivers play a fundamental role in landscape history by setting the boundary conditions for landform evolution. Longitudinal profiles are changed with climatic conditions, lithology and tectonic movements. Tectonic movement is an important factor controlling longitudinal profiles, especially in tectonically active area where uplift rates are regarded as a major factor controlling channel gradient. However study on bedrock channel has made little progress, because controls over bedrock river incision are yet to be clarified. Previous numerical simulations have used a simple diffusion model, which links together the overall processes of bedrock channel erosion as in other landform evolution models. In this study, previous bedrock incision models based on physical processes (especially abrasion) are reviewed and new modifications are introduced. Using newly formulated numerical model, the role of spatial pattern and intensity of tectonic uplift on changes in river longitudinal profile was simulated and discussed.

• Steel and Composite Structures
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• v.34 no.1
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• pp.91-105
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• 2020

Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.109-112
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• 2002

Using Monte Carlo calculations the effects of longitudinal magnetic fields on the beam profiles produced by clinical electron beam were studied. The Monte Carlo calculations were performed using the EGS4 code system modified to account for external magnetic fields. The beam profiles for a 6 MeV electron beam with longitudinal magnetic fields of 0.5-3.0 T were calculated. As a result of these calculations we found that the penumbra widths can be reduced with increased magnetic fields. This means that the electron therapy benefits from the external magnetic fields.

• The korean journal of orthodontics
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• v.15 no.2
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• pp.175-195
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• 1985

Vertical and horizontal growth occur in the craniofacial complex which ensues continuous changes in facial morphology, until the end of active growth period. Longitudinal study for individual is essential, in the research on growth and development, however, the difficulties in obtaining long term subjects in Korea, the research has been limited. The author analyzed the cephalometric roentgenogrems of 43 boys and 47 girls taken from the ages 6 to 10. The subjects were divided into 3 groups according to SN-MP angle and 2 groups according to gonial angle. In this longitudinal study, 21 variables were measure 4. The obtained results were as follows: 1. SN-MP angle and genial angle had no significant changes in each group with age. 2. With age, facial convexity of hard tissue decreased in all groups, facial angle of hard tissue increased in low SN-MP angle group, but facial convexity of soft tissue had no significant changes in all groups with age. 3. In comparison of high SN-MP angle group and low SN-MP angle group, the former had greater facial convexity and smaller facial angle than the latter. 4. SN-MP angle and the ratio of posterior dental height to anterior dental height had reverse correlation in all groups. 5. High genial angle group revealed larger SN-MP angle, anterior dental height facial convexity, but smaller mandibular length, and the ratio of posterior dental height to anterior dental height compared with low genial angle group.