• 제목/요약/키워드: volumetric shrinkage.

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Evaluate the Change of Body Shape and the Patient Alignment State During Image-Guided Volumetric Modulated Arc Therapy in Head and Neck Cancer Patients (두경부 환자의 VMAT 시 체형변화와 환자 정렬과의 상관관계 고찰)

  • Seo, Se Jeong;Kim, Tae Woo;Choi, Min Ho;Son, Jong Gi
    • The Journal of Korean Society for Radiation Therapy
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    • v.29 no.2
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    • pp.109-117
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    • 2017
  • Objectives: The purpose of this study was to evaluate the change of body shape and the patient alignment state during image-guided volumetric modulated arc therapy in head and neck cancer patients, Materials and Methods: We performed a image-guided volumetric modulated arc therapy plan for 89 patients with head and neck cancer who underwent curative radiotherapy. Ten of them were evaluated for set up error. The landmarks of the ramus, chin, posterior neck, and clavicle were specified using ARIA software (Offline review), and the positional difference was analyzed. Results: The re-CT simulation therapy was performed in 60 men with $17{\pm}4$ cycles of treatment. The weight loss rate was $-6.47{\pm}3.5%$. 29 women performed re-CT simulation at $17{\pm}5$ cycles As a result, weight loss rate was $-5.73{\pm}2.7%$. The distance from skin to C1, C3, and C5 was measured, and both clavicle levels were observed to measure the skin shrinkage changes. The skin shrinkage standard deviations were C1 (${\pm}0.44cm$), C3 (${\pm}0.83cm$), and C5 (${\pm}1.35cm$), which is about 1 mm shrinkage per 0.5 kg reduction. Skin shrinkage according to the number of treatments was 1 ~ 4 fractions (no change), 5 ~ 13 fractions (-2 mm), 14 ~ 22 fractions (-4 mm) and 23 ~ 30 fractions (-6 mm). Conclusion: When the body shape changes about 5 mm, the central dose starts to differ about 3 % or more. Therefore, the CT simulation treatment for the adaptive therapy should be additionally performed. In addition, it is necessary to actively study the CT simulation therapy method and set up method of the lower neck and to examine the use of a new immobilization device.

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Optimization of injection molding to minimize sink index with Taguchi's Robust Design technique (다구찌의 강건설계 기법을 이용한 사출 성형품의 싱크 마크를 최소화하기 위한 사출성형 조건의 최적화)

  • Kwon, Youn Suk;Jeong, Yeong Deug
    • Design & Manufacturing
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    • v.1 no.1
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    • pp.17-21
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    • 2007
  • In the manufacture and processing of large plastic materials, product quality is tested and verified through several techniques such as injection processing, residual stress through injection molding and shrinkage. With regards to the injection molding process, common problems such as inconsistent density is seen when different points of the product are discovered to have varying thickness levels. Sink marks in product are then evident. This occurs when there is poor molding conditions caused about by poor runner and packaging systems incorporated into the process. We designed the runner system which is possible balanced filling to cavities using CAE program $Moldflow^{TM}$ and then obtained optimal processing conditions by Taguchi's Robust Design technique.

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A STUDY OF WARPAGE IN ONE WAY LONG PARTS (한 방향으로 긴 제품에 대한 변형연구)

  • Kim, Jong-Kab;Cho, Chae-Sung;Park, Sang-Deuck
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.741-744
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    • 2000
  • In general there occur warpage in one way long part. Warpage is caused by differential shrinkage-Orientation Effect, Volumetric Shrinkage Effect, Differential Cooling Effect -over the part. Deco-Top is located at the top of 29"TV set and it's shape is one way long$(626{\times}130mm)$. Material is used transparency ABS resin. So we can't design ribs in this part. And we use film gate to avoid weld line. In these reasons we must develop no ribs and no warpage product. In this study we use MOLDFLOW's software-MF/FLOW, MF/COOL, MF/WARP. Using MF/FLOW, set the flow balance and gate positioning. And we can set cooling channel layout and the optimum processing condition through MF/COOL and MF/WARP. In result we reduced trials and obtained good product.

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Simulation of injection-compression molding for thin and large battery housing

  • Kwon, Young Il;Lim, Eunju;Song, Young Seok
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1451-1457
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    • 2018
  • Injection compression molding (ICM) is an advantageous processing method for producing thin and large polymeric parts in a robust manner. In the current study, we employed the ICM process for an energy-related application, i.e., thin and large polymeric battery case. A mold for manufacturing the battery case was fabricated using injection molding. The filling behavior of molten polymer in the mold cavity was investigated experimentally. To provide an in-depth understanding of the ICM process, ICM and normal injection molding processes were compared numerically. It was found that the ICM had a relatively low filling pressure, which resulted in reduced shrinkage and warpage of the final products. Effect of the parting line gap on the ICM characteristics, such as filling pressure, clamping force, filling time, volumetric shrinkage, and warpage, was analyzed via numerical simulation. The smaller gap in the ICM parting line led to the better dimensional stability in the finished product. The ICM sample using a 0.1 mm gap showed a 76% reduction in the dimensional deflection compared with the normal injection molded part.

The Conservation of an Woljung Wooden Bridege Structure (월정교지 출토 목재유물의 보존처리)

  • Lee, Chang-Geun;Kim, Ik-Joo;Kim, Sin-Guk
    • 보존과학연구
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    • s.13
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    • pp.9-13
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    • 1992
  • An Woljung wooden bridge structure, which assumde to has been built in the unification of shilla dynasty, was excavated at Nam-chun river basin inKyung-ju. As a result of primary investigation, the weigh loss was 70-80% and the volumetric shrinkage was up to 38% without any conservation. Between 1986 and1991, they were conserved by the two step PEG treatment at the Mokpo Conservation Institute for Maritime Archaeological Finds.

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HNO3 Etching Properties of BaO-B2O3-ZnO-P2O5 System of Barrier Ribs in PDP (플라스마 디스플레이 패널의 격벽용 BaO-B2O3-ZnO-P2O5계의 HNO3를 이용한 에칭 특성)

  • Jeon, J.S.;Kim, J.M.;Kim, N.S.;Kim, H.S.
    • Korean Journal of Materials Research
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    • v.16 no.4
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    • pp.235-240
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    • 2006
  • We investigated the effect of ZnO filler on the microstructure of $BaO-B_2O_3-ZnO-P_2O_5$ glass system to find an etching mechanism of barrier ribs. The sintering behavior of composites heated in the temperature range $560-600^{\circ}C$ was studied by volumetric shrinkage rate and microstructure. The etching test was carried out in $HNO_3$ solution at $50^{\circ}C$ for 10 min. The volumetric shrinkage of sintered sample decreased with the increased firing temperature because of the formation of two crystals. Glass and ZnO filler react forming the $BaZn_2(PO_4)_2$ crystal phases during the sintering process. Etching phenomenon of sintered samples by $HNO_3$ showed that the $BaZn_2(PO_4)_2$ crystal phase was strongly leached compared to glass matrix, crystal phases and fillers. Therefore, the control of interface by condition of sintering is so important to achieve etching effect in barrier ribs.

Polymerization Behavior of Polymeric Dental Restorative Composites Filled with Si-O Bridged Silica (Si-O Bridged 실리카가 충진된 치아수복용 고분자 복합체의 중합 특성)

  • Kim, Ohyoung;Lee, Jung Soo
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.672-676
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    • 2005
  • To improve the application of polymeric dental restorative composite (PDRC) for the posterior and anterior restoration, silica bridged with siloxane unit was firstly prepared by heat-treating a silica filler at various temperatures. Degree of conversion (DC), depth of cure, and dynamic volumetric polymerization shrinkage values of PDRC filled with silica bridged with siloxane unit were investigated to study the effect of heat-treated silica on the polymerization behavior of PDRC. From the experimental result, it was found that depth of cure was decreased with an increase of heat treatment temperature. on the other hand, both DC and polymerization shrinkage values were uniformly enhanced with increasing the heat treatment temperature. This phenomenon can be explained from the study that showed decrease of average particle size of silica resulted in the increase of relative amount of resin matrix in PDRC.

Application of Solidification Analysis considering Volumetric Contraction to Riser Design of Steel Castings (주강품 압탕 설계에 체적 수축을 고려한 응고해석의 적용)

  • Kim, Ji-Joon;Kim, Ki-Young;Choi, Jeong-Kil;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.15 no.5
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    • pp.494-506
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    • 1995
  • Test castings in plate, disc, and cubic shaped castings for 0.2wt.% carbon and stainless steel have been poured to examine the effects of the riser dimensions including riser neck on the casting soundness. Three empirical methods were chosen in risering of steel castings. A computer program of solidification analysis considering liquid and solidification contraction was developed to apply for riserdesign calculated by using their methods in plate, disc, and cubic shaped castings, and to calculate the position and dimension of shrinkage cavity in complex shaped casting. The potential of present method has been successfully demonstrated by comparing predicted cavity shapes with those obtained in a series of experimental castings. Three empirical methods can be used in a practical way to make a rapid estimation of tie minimum riser diameter, but they can not provide a criterion of casting soundness with shape and material on all occasions. The shape and position of shrinkage cavity can be successfully predicted both using the present method and using risering calculated by their methods regardless of the shape and cast material.

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Difference in Solidification Process between Al-Mg Alloy and Al-Si Alloy in Die-Casting (Al-Mg계 합금과 Al-Si계 합금의 다이캐스팅 응고과정의 차이)

  • Choi, Se-Weon;Kim, Young-Chan;Cho, Jae-Ik;Kang, Chang-Seog;Hong, Sung-Kil
    • Korean Journal of Materials Research
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    • v.22 no.2
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    • pp.82-85
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    • 2012
  • The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.

Developement of the reinforced acrylic-based hybrid denture composite resin with vinyloligosilsesquioxane (POSS)

  • Nam, Kwang-Woo;Chang, Myung-Woo;Chang, Bok-Sook;Han, Dong-Hoo;Shim, June-Sung;Chang, Ik-Tae;Heo, Seong-Joo;An, Jung-Ho;Chung, Dong-June
    • The Journal of Korean Academy of Prosthodontics
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    • v.38 no.6
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    • pp.782-790
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    • 2000
  • The mainly used polymeric material for the denture is PMMA because of its cost and easiness to handle. So it was widely used material among dentists for past decades. But the acrylic-based denture materials have several common weak points such as shrinkage after curing and lack of strength. In order to solve these problems, we adapted one of hybrid system using acrylic polymer and vinyloligosilsesquioxane(POSS). POSS, which is a well known expandable monomer during polymerization process, may eventually suppress volumetric shrinkage. And the hybrid system makes it possible for the polymer to be stable in various severe conditions. Eight different kinds of samples were designed and synthesized. Each samples were characterized with dynamic mechanical analyser(DMA) to confirm their thermodynamic properties, fractured to analyze the cross-sectional morphology of the samples. And elongation, flexural and impact tests were also executed to evaluate the mechanical properties of the samples. From the results, hybrid composites had well defined crosslinked network structure compared to the widely used denture materials, and the mechanical strength improved without changing any surface condition as increment with POSS ratio in hybrid system. Fractured morphology showed homogeneous surfaces in spite of mutli component system, therefore we can conclude that the adoption of the POSS brought the reinforcement of the denture resin.

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