• Archives of design research
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• v.19 no.4 s.66
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• pp.17-30
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• 2006

This study is for the size calculation of classroom based on the size of human body and teaching tools. The curriculum of Elementary school has been changed since 1960. It has been reflected on the size of classroom of elementary school. The new education curriculum-the 7th curriculum- demands various activities in classroom. And the Ministry of Education repealed the statute about the facilities of the schools on September in 1997. So we need to different size of unit space of the classroom in elementary school because the size of classroom will affect the quality of education. It is generally known that a part of human body-size has an invariable proportion with human's status, age and weight. In this study, regression analysis is used to find out a part of human body-size of Korean. Then the size of classroom is calculated by the part of human body-size, teaching tools and the type of desk arrangement.

• Journal of Educational Research in Mathematics
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• v.19 no.1
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• pp.143-161
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• 2009

This study was designed to gain insights into students' visualization process in geometric problem solving. The visualization model for analysing visual process for geometric problem solving was developed on the base of Duval's study. The subjects of this research are two Grade 9 students and six Grade 10 students. They were given 2D-geometric problems. Their written solutions were analyzed problem is research depicted characteristics of process of visualization of individually. The findings on the students' geometric problem solving process are as follows: In geometric problem solving, visualization provided a significant insight by improving the students' figural apprehension. In particular, the discoursive apprehension and the operative apprehension contributed to recognize relation between the constituent of figures and grasp structure of figure.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.748-754
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• 2010

To reduce the computational cost required for assembling vessel fragments using surface geometry, this paper proposes a fast axis estimation method. Using circular constraint of pottery and local planar patch assumption, it finds the axis of the symmetry. First, the circular constraint on each cylinder is used. A circular symmetric pot can be thought of unions of many cylinders with different radii. It selects one arbitrary point on the pot fragment surface and searches a path where a circumference exists on that point. The variance of curvature will be calculated along the path and the path with the minimum variance will be selected. The symmetric axis will pass through the center of that circle. Second, the planar patch assumption and profile curve is used. The surface of fragment is divided into small patches and each patch is assumed as plane. The surface normal of each patch will intersects the axis in 3D space since each planar patch faces the center of the pot. A histogram method and minimization of the profile curve error are utilized to find the probability distribution of the axis location. Experimental results demonstrate the improvement in speed and robustness of the algorithms.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.1-10
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• 2002

This paper presents the new template based human face recognition methods to improve the recognition performance against scale and in-plane rotation variations of face images. To enhance the recognition performance, the templates are generated by linear or nonlinear operation on multiple images including different scales and rotations of faces. As the invariant features to allow for scale and rotation variations of face images, we adopt the affine transformation, the log-polar mapping, and the log-polar image based FFT. The proposed recognition methods are evaluated in terms of the recognition rate and the processing time. Experimental results show that the proposed template based methods lead to higher recognition rate than the single image based one. The affine transformation based face recognition method shows marginally higher recognition rate than those of the log-polar mapping based method and the log-polar image based FFT, while, in the aspect of processing time, the log-polar mapping based method is the fastest one.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.203-212
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• 2002

The purpose of this study was to examine the effect of vegetation on the flood plain in the Taewha river on the changes of flood level using a hydraulic physical model experiment. To simulate 9.0 km river, 1/300 horizontally and 1/72 vertically distorted model was used. The vegetation areas were divided by three sub -areas and the flood level changes were examined according to the locations of vegetation as well as the transverse Profile. As a result, the flood level changes were not significantly affected by the densely distributed vegetation. It was concluded that additional adjustable vegetation in urban river could make useful hydrophilic space.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.376-385
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• 1987

In this study, the plane stress fracture toughness and Tearing modulus are investigated for various crack ratios using the J integral. To evaluate the J integral and Tearing modulus, both experiments and estimation are used. The thickness of the low carbon steel specimens that is used in the experiments is 3mm. The type of specimen that is considered in the study is center-cracked-tension one. The measurements of crack length are performed by unloading compliance method. In the estimation of crack parameters such as the J integral and load line displacement, the Ramberg and Osgood stress strain law is assumed. Then simple formulas are given for estimating the crack parameters from contained yielding to fully plastic solutions. Obtained results are as follows; (1) When the crack ratio is in the range of 0.500 - 0.701, the plane stress fracture toughness is almost constant regardless of crack ratios. (2) The fracture toughness (J$\_$c/) and Tearing modulus (T) obtained are J$\_$c/=28.51kgf/mm, T=677.7 for base metal, J$\_$c/=31.85kgf/mm, T=742.0 for annealed metal. (3) Simpson's and McCabe's formulas which consider crack growth in estimating J integral are shown more conservative J and lower T than Rice's and Sumpter's. (4) Comparison of the prediction with the actual experimental measurements by Simpson's formula shows good agreement.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.614-614
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• 2012

개수로에서 혹은 수리구조물 주변에서의 흐름 및 난류 특성을 파악하기 위해서는 연직유속분포 및 수심별 평면유속분포의 측정이 필요하다. 유속분포를 측정하기 위한 방법은 음파 도플러 유속계(ADV:Acoustic Doppler Velocimetry)를 사용하는 방법과 PIV 기법을 이용하는 방법이 있다. 일반적으로 ADV는 한 지점의 유속을 시간변화에 따라 연속적으로 측정할 수 있어 난류특성의 정량적인 해석에 장점이 있으나 동시간에 여러 지점을 측정할 수 없기 때문에 난류의 공간적인 문제를 해석함에 있어서 한계가 있다. 그러나, 입자영상유속계(PIV:Particle Image Velocity)는 측정하고자 하는 단면에서 연직 횡단면의 유속분포 및 수심별 평면 유속분포 흐름장 측정이 가능하여 난류흐름의 공간적인 문제를 해석하는데 효과적일 뿐만 아니라 영상간의 시간간격을 짧게 하고, 촬영시간을 충분히 길게 한다면 개수로 내 난류특성 분석도 가능하다. 이에 본 연구의 목적은 PIV 기법을 이용하여 매끄러운 하상의 개수로에서 연직유속분포를 측정하고 그 특성을 정량적으로 분석하고자 한다. 본 연구에서는 첫째, PIV 기법을 이용하여 측정한 연직유속분포와 3차원 전자식 유속계를 이용하여 측정한 연직유속분포를 비교 분석하였다. 둘째, 후류법칙에 의해 계산된 연직유속분포와 PIV 기법을 이용하여 측정한 연직유속분포의 비교를 위해 각각의 무차원 유속분포(지점 유속/지점 마찰속도)를 계산하고 비교하였다. 마지막으로 각 흐름 조건에 따라 수심의 변화를 주어 연직유속분포를 PIV 기법으로 측정한 후 개수로의 수심변화에 따른 연직유속의 특성을 분석하였다. 분석 결과, PIV 기법을 이용하여 측정한 연직유속 성분에 비해 3차원 전자식 유속계로 측정한 연직유속 성분이 작게 나타났고 바닥에서부터 0.2h 지점까지는 무차원 유속분포(지점 유속/지점 마찰속도)가 후류법칙과 잘 맞는 경향을 보였으나 0.2h 지점부터 수표면까지는 유속이 감소하는 현상이 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1345-1349
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• 2004

하천수를 취수원으로 하는 우리나라의 많은 취수장의 경우, 유사유입 및 유로 변경에 따른 취수장애를 겪고 있으나 유로의 변화특성을 분석하고 취수장 위치선정에 활용한 수 있는 실무적 기법에 대한 연구는 거의 없는 실정이다. 따라서 본 연구에서는 유로가 좌${\cdot}$우안으로 수시로 바뀌어 갈수기는 물론 평수기에도 취수장애를 겪고 있어 대책 강구가 요구되는 국내 취수장을 선정하고 취수지점의 계속적인 하상 및 유로변동 현상을 규명하여 안정적인 취수를 가능케 하는 근본적인 대책을 수립하기 위한 유로변화 특성 분석기법을 제시하였다. 연구내용으로는 과거 30여년에 걸친 하도의 평면학적 변화양상을 인공위성영상자료, 지형도자료 및 하도단면 실측자료를 활용하여 각 지점별 유로변화에 대한 동계분석을 실시하였다. 또한 하도의 전단응력, 마찰 속도 등을 산정하여 하상형태를 분석하여 대상구간의 흐름특성을 분석하였다. 분석결과 하도의 사행은 지속적으로 진행되고 있음을 알 수 있으며 특히 취수장부터 상류 수km구간 하도에서는 밤섬이 지속적으로 생긴다 사라지는 현상이 반복되고 있음을 확인할 수 있었다. 취수장 주변에서는 유로의 변동이 하폭의 $70\%$에 달하는 심한 유로변화 특성을 나타내고 있어 취수지점으로 적당치 못함을 알수 있었으며 주변 상하류 십수 km구간 중에는 유로의 변화가 거의 없는 구간도 존재함을 알 수 있이 본 연구의 유로변화 분석기법이 향후 유로변화 분석 및 취수장 건설 위치 선정에 효과적인 분석기법으로 활용 가능함을 입증하였다.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.170-174
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• 1993

The quantitative methods for the assessment of the cerebral blood flow using $^{99m}Tc$-HMPAO brain SPECT utilize the measured count distribution in some specific reconstructed tomographic slice or in algebraic summation of a few neighboring slices, rather than the true volumetric distribution, to estimate the relative regional cerebral blood flow, and consequently produce the biased estimates of the true regional cerebral blood flow. This kind of biases are thought to originate mainly from the arbitrarily irregular shape of the cerebral region of interest(ROI) which are analyzed. In this study, a semi-automated method for the direct quantification of the volumetric regional cerebral blood flow estimate is proposed, and the results are compared to those calculated by the previous planar approaches. Bias factors due to the partial volume effect and the uncertainty in ROI determination are not considered presently for the methodological comparison of planar/volumetric assessment protocol.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.383-397
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• 2010

Objective: The objective of this study was to compare maxillary soft tissue changes and their relative ratios to hard tissue changes after anterior segmental osteotomy (ASO)/bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I/BSSRO in skeletal Class III malocclusion with upper lip protrusion. Methods: The study sample comprised the ASO/BSSRO group (n = 14) and the Le Fort I/BSSRO group (n = 15). The Le Fort I/BSSRO group included cases of maxillary posterior impaction only. Lateral cephalograms were taken 2 months before and 6 months after surgery. Linear and angular measurements were performed. Results: The anterior maxilla moved backward in both groups after surgery, however the amount of change was significantly larger in the ASO/BSSRO group (p < 0.01). The ratios of hard to soft tissue change were 79% (SLS to A point), 80% (LS to A point) in the ASO/BSSRO group, and 15% (SLS to A point), 68% (LS to A point) in the Le fort I/BSSRO group. In addition, there was a $3.23^{\circ}$ increase of the occlusal plane in the Le Fort I/BSSRO group. Conclusions: When two-jaw surgery is indicated in skeletal Class III patients with protrusive lips, ASO may be a treatment of choice for cases with more severe upper lip protrusion, while Le Fort I with posterior impaction may be considered if an increase of occlusal plane angle is required.