• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.1-8
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• 2015

This paper presents finite element (FE) analyses to clarify the effects of external pressure on the residual stresses in a girth-welded steel pipe. At first, FE simulation of the girth welding process is carried out to obtain the weld-induced residual stresses employing sequentially coupled three-dimensional (3-D) thermo-mechanical FE formulation. Then, 3-D elastic-plastic FE analyses incorporating the residual stresses and plastic strains obtained from the preceding FE simulation are performed to investigate the residual stress behavior in the girth-welded pipe under external pressure. The FE analysis results show that the hoop compressive stresses induced by the external pressure significantly alter the hoop residual stresses in the course of the mechanical loading.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.95-100
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• 2009

This study was conducted to develop an imaging processing system of inoculation processing of a lily callus. The image processing system was composed of a camera, a image processing board, and etc. And the illuminance always decided by setting up 55W/3 wavelength lamp respectively on all aspects and the side was maintained by the lighting part. The image characteristic was examined according to each frame of RGB,therefore the culture vessel was able to be separated with B frame. The required time was 2.2 seconds in one cycle from the image acquisition to obtaining the result. The recognition rate of the container was 100%, and the result of image processing showed that the recognition success rate of lily callus was 93%.

• Journal of Korea Water Resources Association
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• v.48 no.2
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• pp.137-147
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• 2015

This study performed the systematic classification of the various types of riffles and analyzed their physical and hydraulic characteristics at the Hongcheon River and Seomjin River. The riffles are classified into the long type and the wide type by their ratio of length and width, and also classified into the convergent type and the divergent type by their width change along flow direction. They are also classified into the falling type, the running type, the undular wave and the undular jump by their surface profiles. The falling type and the running type usually occur near the cobbles with multiple diameters, whereas the undular wave and the undular jump occur near the small pebbles. They showed the upward convex type at the middle part, and the slope gets bigger at the downstream part.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.431-438
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• 2005

A steel-concrete composite column is a recently developed composite system in which the two opposite flanges of the H-shape section are connected by welded links, and the vacant space enclosed by the flanges, web, and links is filled with concrete. Previous experiments on the SC composite column were performed to evaluate its compression and bending and shear strengths, respectively, and they showed fairly good results. In addition to thesestudies, it may be necessary to evaluate the flexural-axial capacity of an SC composite column, because itscolumn members are generally subjected to axial force and bending moment at the same time. In this study, the bending strength of an SC composite column subjected to axial compression force was investigated experimentally. The results of the study showed that the AISC-LRFD provisions representedexcessively low values compared with those of the ACI, Eurocode-4, and Japan Code provisions. The Eurocode-4 provisions represented reasonable evaluations of the strength of the SC composite column composed of a non-compact section.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.341-348
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• 2017

This study examined the effects of the location and direction of the scolioti curve on postural balance in patients with idiopathic scoliosis. Fifteen subjects were divided into three groups: right thoracic curve group, left lumbar curve group, and double curve group. The dynamic trunk motion (angle variation in the lumbar, thoracolumbar, lower thoracic and upper thoracic region) and plantar pressure distribution (maximum force and peak pressure) were assessed using an ultrasound-based motion analysis system and Emed-at platform system. From the results, it was confirmed that patients with idiopathic scoliosis showed postural imbalance with an increased angle and pressure asymmetry according to the location and direction of the scoliotic curve for dynamic trunk motion and plantar pressure distribution. In addition, there were differences in the postural balance pattern between the single curve and double curve groups. Further studies for developing a rehabilitation training device will be conducted to improve the postural control ability and trunk balance as well as treat scoliosis based on the results of this study.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.664-676
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• 1996

테트라싸이클린에 의한 치아 변색은 심미성을 고려한 임상 치료시 커다란 난제로 남아 있다. 본 연구는 백서 치아에 테트라싸이클린을 주입하여 야기되는 색상과 구조적인 변화도를 측정하여 향후 연구에 기초자료를 제공하기 위해 시행되었다. 24 마리의 백서를 각기 8 마리씩 3 군으로 분류하여 대조군은 정상적인 사육을 식염수군은 TC군과 동량의 식염수를 주사하였으며 TC군은 12 ml에 용해시킨 60 mg의 테트라싸이클린을 복강내로 2 주간 주입하였다. 최종 주입후 1 주간 정상 사육한 다음 cervical dislocation법에 의해 희생시켜 시편을 채득한 후 각 치아를 횡단하여 실물현미경과 FlexCam을 이용하여 컴퓨터에 영상을 저장한 다음 색 변화량을 Adobe Photoshop으로 측정하였으며 구조변화는 주사전자 현미경을 이용하였다. 치아색 변화량의 유의성 검정은 ANOVA와 Scheffe test를 이용하였으며 본 실험 결과는 다음과 같다. 1. 각 군의 $a^*$ 수치는 대조군 -6.12 (1.18), 식염수군 -8.00 (1.33), TC군 -18.56 (2.52)로 나타났으며 $b^*$ 수치는 대조군 1.12 (2.13), 식염수군 1.62 (1.45), TC군 28.67 (5.18)을 보였다. 즉 테트라싸이클린에 의해 $a^*$와 $b^*$의 수치가 유의성있게 (p<0.01) 초록색과 노란색 방향으로 변화하였다. 2. 테트라싸이클린에 의해 치경부 법랑질 외면이 검게 변색되었으며 울퉁불퉁한 양태로 변화되었다. 그러나 법랑소주의 형태, 방향등은 차이를 보이지 않았다. 3. 각 군간 상아세관의 수, 방향, 크기등이 차이가 없었다. 치수측에서의 관찰결과 대조군과 식염수군에서는 상아세관들의 입구가 크고 명확하게 보인 반면 TC군에서는 입구가 좁고 부분적으로 막힌 양태도 관찰되었다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.97-105
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• 2009

This paper studied the cause of the deterioration of the four 3-Arch tunnels built in mid-1990. The common deteriorations of the four 3-Arch tunnels were longitudinal cracks, leakage and efflorescence at the same parts of lining concrete. Three fourths of 3-Arch tunnels, there was high percentage longitudinal cracks and a quarter was low frequency about longitudinal cracks. So the material reviewed to find out the differences between two groups in construction process and analysis was conducted such as non-destructive testing, precise visual survey and safety evaluation of one tunnel which had bad ground condition As the result, the tunnels were safety condition and the primary deterioration occurred during the construction process, namely, problems arrangement of rebar and the effects of the blast at middle tunnel.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.839-853
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• 1998

The present study was performed to prove the relationship between CO-CR discrepancy and facial skeletal type. In this study, 242 subjects were randomly selected and devided into 9 groups(devided into class I, II, III by ANB and each one devided into dolicho-, brachy-, mesofacial skeleton by Ricketts' vertical index). Lateral cephalometric radiographs with the mandible in centric occlusion were taken and measured and CO and CR bites were registered on all subjects. Diagnostic casts were mounted on Panadent articulator using an estimated face-bow and centric relation bite registration. The amount and direction of CO-CR discrepancy present was recorded using a Condylar Position Indicator(CPI) and a centric occlusion wax bite registration. CPI measurements and cephalometric measurements were statistically analyzed. The finding of this study can be summerized as follows : 1. There is little correlation between right and left sides for magnitude or direction of CO-CR discrepancies. The correlation between the magnitude of CO-CR discrepancy of left A-P and right A-P is higher than that of left S-I and right S-I. 2. Correlation of Class II malocclusion group was higher than that of the other groups between the magnitude of CO-CR discrepancy of left CPI and right CPI. 3. There is no difference between the pattern of CO-CR discrepancy of 9 malocclusion groups. 4. There is very little, if any, correlation between Skeletofacial measurements and CO-CR discrepancy. 5. In Class II brachyfacial skeleton and Class III mesofacial skeleton there was Lateral cephalometric measurements by that we predict CPI measurements was detected. That was overbite, overjet, upper genial angle, lower genial angle, saddle angle, articular angle, convexity of point A, ANS-Me/Na-Me, PCBL/RH, Posterior FH/anterior FH.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.353-370
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• 1998

This study was conducted to investigate the changes in the structural parts of the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class III patients. The subject consisted of 29 Korean children(14 males, 15 females) who had skeletal Class III malocclusion and were undergone chincap therapy from the beginning of the treatment (and an auxilliary upper removable appliance, if necessary). The control group was composed of 21 children(10 males, 11 females) with skeletal Class III malocclusion who had no orthodontic treatment. Cephalometric data at the mean age of 7 and 2 years later were analyized by finite element method, and compared between groups by independent group t-test(p<0.05). The results of the present study were as follows; 1. There were no significant changes in the cranial base, posterior face, upper anterior face, ramus, chin and soft tissues by the chincap therapy. 2. The mandibular body showed significant differences in the minimum extention ratio and the overall shape ratio. This means that the vertical direction of growth was retarded by the chincap therapy. 3. The major direction of the growth in the maxillary basal bone was significantly more horizontal in the experimental group, which suggests that the vertical growth of maxilla was inhibited. 4. There was statistical difference in the major direction of the growth of the anterior face between groups. This may be due to the significant difference in the major direction of growth of the lower anterior face, supposed to be resulted from the mandibular rotation and/or displacement by the chincap therapy. The change in the oral functional space seemed to be caused by the same reason. 5. From the standpoint of these results, the retardation of growth, the changes of the growth direction and the morphological changes could be accepted partly, but the major effect of the chincap seems to be the rotation and the displacement of the mandible.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.1-8
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• 1985

Stability analysis of the embankment as to water level varation is the most important problem in the safety of the slope because the stress of embankment inside varies as to drawdown of seepage line. Especially when the water level is rapidly drawdown, because the flow direction of the free surface changes the toe of embankment, the factor of safety comes to small, therefore the embankment is dangered. For the purpose of studing these phenomena, the experimental models are built with sand in the laboratory. In the experimental consideration, the falling seepage line and the shape of failure are measured. This paper intends to study the failure slip surface, the relationship between the factor of safety and drawdown velocity, and hydraulic gradient. The results of the experimental study are summarized as follows; 1. Owing to the drawdown of free surface, sliding failure occurred in the upstream fill, the height of failure is 5~10, 9~15, and 13~21(cm) in each model. 2. In consideration of the distribution of pore water pressure Table-5 shows each factor of safety. In the relationship between the drawdown velocity and the factor of factor it's velocity should be limited to 0.21~0.28 (cm/sec), according to each models. In the relationship between the factor of safety and the hydraulic gradient within the upstream slope, it's gradient must be below 0.36~0.43.