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Experimental Validation of Isogeometric Optimal Design (아이소-지오메트릭 형상 최적설계의 실험적 검증)

  • Choi, Myung-Jin;Yoon, Min-Ho;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.5
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    • pp.345-352
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    • 2014
  • In this paper, the CAD data for the optimal shape design obtained by isogeometric shape optimization is directly used to fabricate the specimen by using 3D printer for the experimental validation. In a conventional finite element method, the geometric approximation inherent in the mesh leads to the accuracy issue in response analysis and design sensitivity analysis. Furthermore, in the finite element based shape optimization, subsequent communication with CAD description is required in the design optimization process, which results in the loss of optimal design information during the communication. Isogeometric analysis method employs the same NURBS basis functions and control points used in CAD systems, which enables to use exact geometrical properties like normal vector and curvature information in the response analysis and design sensitivity analysis procedure. Also, it vastly simplify the design modification of complex geometries without communicating with the CAD description of geometry during design optimization process. Therefore, the information of optimal design and material volume is exactly reflected to fabricate the specimen for experimental validation. Through the design optimization examples of elasticity problem, it is experimentally shown that the optimal design has higher stiffness than the initial design. Also, the experimental results match very well with the numerical results. Using a non-contact optical 3D deformation measuring system for strain distribution, it is shown that the stress concentration is significantly alleviated in the optimal design compared with the initial design.

A study on the effect of tunnelling to adjacent single piles and pile groups considering the transverse distance of pile tips from the tunnel (말뚝의 횡방향 이격거리를 고려한 터널굴착이 인접 단독말뚝 및 군말뚝에 미치는 영향에 대한 연구)

  • Jeon, Young-Jin;Kim, Sung-Hee;Lee, Cheol-Ju
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.6
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    • pp.637-652
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    • 2015
  • In the present work, a number of three-dimensional (3D) parametric numerical analyses have been carried out to study the influence of tunnelling on the behaviour of adjacent piles considering the transverse distance of the pile tip from the tunnel. Single piles and $5{\times}5$ piles inside a group with a spacing of 2.5d were considered, where d is the pile diameter. In the numerical modelling, several key issues, such as the tunnelling-induced pile settlements, the interface shear stresses, the relative shear displacements, the axial pile forces, the apparent factors of safety and zone of influence have been rigorously analysed. It has been found that when the piles are inside the influence zone, the pile head settlements are increased up to about 111% compared to those computed from the Greenfield condition. Larger pile settlements and smaller axial pile forces are induced on the piles inside the pile groups than those computed from the single piles since the piles responded as a block with the surrounding ground. Also tensile pile forces are induced associated with the upward resisting skin friction at the upper part of pile and the downward acting skin friction at the lower part of pile. On the contrary, when the piles were outside the influence zone, tunnelling-induced compressive pile forces developed. Based on computed load and displacement relation of the pile, the apparent factor of safety of the piles was reduced up to about 45%. Therefore the serviceability of the piles may be substantially reduced. The pile behaviour, when considering the single piles and the pile groups with regards to the influence zone, has been analysed by considering the key features in great details.

Evaluation of Manufactured Device for Radiation therapy in Head and Neck Cancer (두경부암 환자의 방사선 치료시 자체 제작한 고정용구 (Shoulder Retractor)에 대한 유용성 평가)

  • Kim, Tae Jun;Jin, Sun Sik;Kim, Dong Hyun;Kim, Dong Wook;Chung, Weon Kuu;Kim, Kyoung Tae
    • The Journal of Korean Society for Radiation Therapy
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    • v.26 no.1
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    • pp.99-105
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    • 2014
  • Purpose : We compared the set-up accuracy and right-left Shoulder position variation of the manufactured device and other commercial shoulder-retractors in the head and neck radiation treatment. Materials and Methods : Six patients consist of three groups which were used three different Shoulder retractors. We measured position corrections of left and right Shoulder and the couch after the image guidance by using on board imager (OBI) for six head and neck patients who has the extended target to the neck node lower region. Results : The position variation correction of left (right) Shoulder after image guidance were $1.07{\pm}3.99mm$ ($-4.35{\pm}2.09mm$), $-0.37{\pm}5.91mm$ ($1.26{\pm}5.28mm$), $-0.63{\pm}2.44mm$ ($0.25{\pm}1.61mm$) for group A, B and C. The vertical, lateral, longitudinal position and angular corrections of the couch after image guidance were $-2.06{\pm}2.68$, $-1.11{\pm}8.15$, $0.34{\pm}3.78mm$, and $0.51{\pm}0.77$ degree for group A, $-1.18{\pm}1.82$, $-0.94{\pm}2.13$, $-0.67{\pm}1.98mm$, and $0.91{\pm}1.04$ degree for group B and $0.12{\pm}2.18$, $-0.79{\pm}2.64$, $0.79{\pm}2.64$, and $0.00{\pm}0.49$ degree for group C. Conclusion : In this preliminary study, we found the positioning accuracy of the manufactured Shoulder retractor is comparable to other commercial Shoulder retractors. We expect that the reproducibility and accuracy of the patient set-up could be improved by using the home made Shoulder retractor in the head and neck radiation treatment.

Experimental Performance Evaluation of Steel Mesh as Maintenance and Reinforcement Materials (Steel Mesh Cement Mortar의 보수⋅보강 성능 평가)

  • Kim, Yeon-Sang;Choi, Seung-Jai;Kim, Jang-Ho Jay
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.4
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    • pp.50-58
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    • 2014
  • Due to the cost burden of new construction, the necessity of repair and retrofitting of aged structures is sharply increasing as the domain of repair and retrofitting construction is expanding. Because of the necessity, new technologies for repair and retrofitting are continuously studied in Korea and foreign countries. Steel adhesive method, fiber reinforced plastic (FRP) surface adhesive method, and external prestressing method are used to perform the repair and retrofitting works in Korea. In order to consider a repair method using steel mesh reinforced cement mortar (SMCM), 3-point flexural member test was conducted considering repair area and layer number of SMCM. Five types of specimens including ordinary reinforced concrete (RC) specimen with dimensions of $1400{\times}500{\times}200$ (mm) were cast for testing the deflection measurement, a LVDT was installed at the top center of the specimens. Also, a steel strain gauge and a concrete strain gauge were placed at the center of the specimens. A steel strain gauge was also installed on the shear reinforcement. The 3 point flexural member test results showed that the maximum load of SMCM reinforced specimen was higher than that of basic RC specimen in all of the load-displacement curves. Also, the results showed that, when the whole lower part of the basic RC specimen was reinforced, the maximum load and strain were 1.18 and 1.37 times higher than that of the basic RC specimen, respectively. Each specimen showed a slightly different failure behavior where the difference of the results was caused by the difference in the adhesive level between SMCM and RC. Particularly, in SM-B1 specimen, SMCM spalled off during the experiment. This failure behavior showed that the adhesive performance for RC must be improved in order to utilize SMCM as repair and retrofitting material.

Finite Element Analysis of Bone Stress Caused by Horizontal Misfit of Implant Supported Three-Unit Fixed Prosthodontics (3차원 유한요소법에 의한 임플란트 지지 3본 고정성 가공 의치의 부적합도가 인접골 응력에 미치는 영향 분석)

  • Lee, Seung-Hwan;Jo, Kwang-Hun
    • Journal of Dental Rehabilitation and Applied Science
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    • v.28 no.2
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    • pp.147-161
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    • 2012
  • This study is to assess the effect of horizontal misfit of an implant supported 3-unit fixed prosthodontics on the stress development at the marginal cortical bone surrounding implant neck. Two finite element models consisting of a three unit fixed prosthodontics and an implant/bone complex were constructed on a three dimensional basis. The three unit fixed prosthodontics were designed either shorter (d=17.8mm model) or longer (d=18.0mm model) by 0.1mm than the span of two implants placed at the mandibular second premolar and second molar areas 17.9mm apart. Fitting of the fixed prosthodontics onto the implant abutments was simulated by a total of 6 steps, that is to say, 0.1mm displacement per each step, using DEFORM 3D (ver 6.1, SFTC, Columbus, OH, USA) program. Stresses in the fixed prosthodontics and implants were evaluated using von-Mises stress, maximum compressive stress, and radial stress as necessary. The d=17.8mm model assembled successfully on to the implant abutments while d=18.0mm model did not. Regardless if the fixed prosthodontics fitted onto the abutments or not, excessively higher stresses developed during the course of assembly trial and thereafter. On the marginal cortical bone around implants during the assembly, the peak tensile and compressive stresses were as high as 186.9MPa and 114.1MPa, respectively, even after the final sitting of the fixed prosthodontics (for d=17.8mm model). For this case, the area of marginal bone subject to compressive stresses above 55MPa, equivalent of the $4,000{\mu}{\varepsilon}$, i.e. the reported threshold strain to inhibit physiological remodeling of human cortical bone, extended up to 2mm away from implant during the assembly. Horizontal misfit of 0.1mm can produce excessively high stresses on the marginal cortical bone not only during the fixed prosthodontics assembly but also thereafter.

Transfer and Validation of NIRS Calibration Models for Evaluating Forage Quality in Italian Ryegrass Silages (이탈리안 라이그라스 사일리지의 품질평가를 위한 근적외선분광 (NIRS) 검량식의 이설 및 검증)

  • Cho, Kyu Chae;Park, Hyung Soo;Lee, Sang Hoon;Choi, Jin Hyeok;Seo, Sung;Choi, Gi Jun
    • Journal of Animal Environmental Science
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    • v.18 no.sup
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    • pp.81-90
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    • 2012
  • This study was evaluated high end research grade Near infrared spectrophotometer (NIRS) to low end popular field grade multiple Near infrared spectrophotometer (NIRS) for rapid analysis at forage quality at sight with 241 samples of Italian ryegrass silage during 3 years collected whole country for evaluate accuracy and precision between instruments. Firstly collected and build database high end research grade NIRS using with Unity Scientific Model 2500X (650 nm~2,500 nm) then trim and fit to low end popular field grade NIRS with Unity Scientific Model 1400 (1,400 nm~2,400 nm) then build and create calibration, transfer calibration with special transfer algorithm. The result between instruments was 0.000%~0.343% differences, rapidly analysis for chemical constituents, NDF, ADF, and crude protein, crude ash and fermentation parameter such as moisture, pH and lactic acid, finally forage quality parameter, TDN, DMI, RFV within 5 minutes at sight and the result equivalent with laboratory data. Nevertheless during 3 years collected samples for build calibration was organic samples that make differentiate by local or yearly bases etc. This strongly suggest population evaluation technique needed and constantly update calibration and maintenance calibration to proper handling database accumulation and spread out by knowledgable control laboratory analysis and reflect calibration update such as powerful control center needed for long lasting usage of forage analysis with NIRS at sight. Especially the agriculture products such as forage will continuously changes that made easily find out the changes and update routinely, if not near future NIRS was worthless due to those changes. Many research related NIRS was shortly study not long term study that made not well using NIRS, so the system needed check simple and instantly using with local language supported signal methods Global Distance (GD) and Neighbour Distance (ND) algorithm. Finally the multiple popular field grades instruments should be the same results not only between research grade instruments but also between multiple popular field grade instruments that needed easily transfer calibration and maintenance between instruments via internet networking techniques.

The study of stereoscopic editing process with applying depth information (깊이정보를 활용한 입체 편집 프로세스 연구)

  • Baek, Kwang-Ho;Kim, Min-Seo;Han, Myung-Hee
    • Journal of Digital Contents Society
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    • v.13 no.2
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    • pp.225-233
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    • 2012
  • The 3D stereoscopic image contents have been emerging as the blue chip of the contents market of the next generation since the . However, all the 3D contents created commercially in the country have failed to enter box office. It is because the quality of Korean 3D contents is much lower than that of overseas contents and also current 3D post production process is based on 2D. Considering all these facts, the 3D editing process has connection with the quality of contents. The current 3D editing processes of the production case of are using the way that edits with the system on basis of 2D, followed by checking with 3D display system and modifying, if there are any problems. In order to improve those conditions, I suggest that the 3D editing process contain more objectivity by visualizing the depth data applied in some composition work such as Disparity map, Depth map, and the current 3D editing process. The proposed process has been used in the music drama , comparing with those of the film . The 3D values could be checked among cuts which have been changed a lot since those of , while the 3D value of drew an equal result in general. Since the current process is based on an artist's subjective sense of 3D, it could be changed according to the condition and state of the artist. Furthermore, it is impossible for us to predict the positive range, so it is apprehended that the cubic effect of space might be perverted by showing each different 3D value according to cuts in the same space or a limited space. On the other hand, the objective 3D editing by applying the visualization of depth data can adjust itself to the cubic effect of the same space and the whole content equally, which will enrich the 3D contents. It will even be able to solve some problems such as distortion of cubic effect and visual fatigue, etc.

Cooling and Thermal Histories of Cretaceous-Paleogene Granites from Different Fault-bounded Blocks, SE Korean Peninsula: Fission-track Thermochronological Evidences (한반도 동남부의 주단층대에 의해 구분된 지질블록별 백악기-고제3기 화강암의 차별적 냉각-지열 이력: 피션트랙 열연대학적 증거)

  • Shin, Seong-Cheon
    • The Journal of the Petrological Society of Korea
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    • v.21 no.3
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    • pp.335-365
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    • 2012
  • Fission-track (FT) thermochronological records from SE Korean Cretaceous-Paleogene granitic plutons in different fault-bounded blocks reveal contrasting cooling and later thermal histories. Overall cooling patterns are represented by a monotonous (J-shaped) curve in most plutons except some Cretaceous granites retaining a complicated (N-shaped) path due to post-reset re-cooling. Discriminative cooling rates over different temperature ranges can be explained for individual plutons with respect to relative pluton sizes, differences in initial heat loss depending on country rocks, and the presence and proximity of later igneous activity. Even within a single batholith, cooling times for different isotherms were roughly contemporaneous with respect to positions. Insignificant deviations in cooling ages from two different plutons in succession across the Yangsan fault may suggest their contemporaneity before major horizontal fault movement. The extent of later thermal rise recorded locally along the Yangsan and Dongnae fault zones were reached the Apatite Partial Stability Zone ($70-125^{\circ}C$), but did not exceed $200^{\circ}C$. Thermal alteration from fractured zones in the Yangsan-Ulsan fault junction may suggest a thermal reset above $290^{\circ}C$ resulting a complete reset in FT sphene age (31 Ma), caused by a tectonic subsidence in Early Oligocene. A consistency in FT zircon/apatite ages (24 Ma) may imply a sudden rapid cooling over $200-105^{\circ}C$, plausibly related to the abrupt tectonic uplift of the Pohang-Gampo Block including the fault junction in Late Oligocene. A remarkable trend of lower cooling ages for $300-200-100^{\circ}C$ isotherms (i.e., 19% for FT sphene and K-Ar biotite; 20% for FT zircon; 27% for FT apatite) from the east of the Ulsan fault (Pohang-Gampo Block) comparing to the west of the fault may be attributed to retarded cooling times from the Paleogene granites and also reflected by their partially-reduced apatite ages due to later thermal effects.

Application of PCM Technology to Concrete II : Effects of SSMA(Sulfonated Styrene-Maleic Anhydride) on the Properties of the 1-Dodecanol Micro-Capsule (PCM 기술의 콘크리트 적용 II : 계면중합법에 의한 1-도데카놀 마이크로 캡슐에 있어서 계면활성제로 사용된 SSMA의 표면활성도가 마이크로 캡슐의 특성에 미치는 영향)

  • Shin, Se-Soon;Jung, Jae-Yun;Lim, Myung-Kwan;Choi, Dong-Uk;Kim, Young-Ho
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.1 no.1
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    • pp.17-25
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    • 2013
  • Thermal storage technology used for indoor heating and cooling to maintain a constant temperature for a long period of time has an advantage of raising energy use efficiency. This, the phase changing material, which utilizes heat storage properties of the substances, capsulizes substances that melt at a constant temperature. This is applied to construction materials to block or save energy due to heat storage and heat protection during the process in which substances melt or freeze according to the indoor or outdoor temperature. The micro-encapsulation method is used to create thermal storage from phase changing material. This method can be broadly classified in 3 ways: chemical method, physical and chemical method and physical and mechanical method. In the physical and chemical method, a wet process using the micro-encapsulation process utilized. This process emulsifies the core material in a solvent then coats the monomer polymer on the wall of the emulsion to harden it. In this process, a surfactant is utilized to enhance the performance of the emulsion of the core material and the coating of the wall monomer. The performance of the micro-encapsulation, especially the coating thickness of the wall material and the uniformity of the coating, is largely dependent on the characteristics of the surfactant. This research compares the performance of the micro-capsules and heat storage for product according to molecular mass and concentration of the surfactant, SSMA (sulfonated styrene-maleic anhydride), when it comes to micro-encapsulation through interfacial polymerization, in which Dodecan-1 is transformed to melamin resin, a heat storage material using phase changing properties. In addition, the thickness of the micro-encapsulation wall material and residual melamine were reduced by adjusting the concentration of melamin resin microcapsules.

A study of lower facial change according to facial type when virtually vertical dimension increases (가상적 수직 교합 고경 증가 시 안모의 유형에 따른 하안모 변화에 관한 연구)

  • Kim, Nam-Woo;Lee, Gung-Chol;Moon, Cheol-Hyun;Bae, Jung-Yoon;Kim, Ji-Yeon
    • The Journal of Korean Academy of Prosthodontics
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    • v.54 no.1
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    • pp.1-7
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    • 2016
  • Purpose: The aim of this study was to evaluate the effect of increased vertical dimension of occlusion on lower facial changes by facial type. Materials and methods: Lateral cephalograms from 261 patients were obtained and classified by sagittal (Class I, II, and III) and vertical (hypodivergent, normodivergent, and hyperdivergent) facial patterns. Retrusive displacement of soft tissue Pogonion and downward displacement of soft tissue Menton were measured in each group after 2 mm of vertical dimension of occlusion was increased at the lower central incisor using a virtual simulation program. The ratio of both displacements was calculated in all groups. The statistical analysis was done by 2-way ANOVA and Post hoc was done by Tukey test (5% level of significance). Results: Retrusive displacement of soft tissue Pogonion in Class III group was statistically different compared to Class I and II, and in vertical facial groups all 3 groups were significantly different (P<.05). Downward displacement of soft tissue Menton showed statistically significant difference between all sagittal groups and vertical groups (P<.05). The ratio of both displacements showed statistically significant difference in all sagittal groups and vertical groups (P<.05), and Class II hyperdivergent group had the highest value. Conclusion: Lower facial change was statically significant according to the facial type when vertical dimension of occlusion increased. Class II hyperdivergent facial type showed the highest ratio after increase in vertical dimension of occlusion.