• Title/Summary/Keyword: Mold Shape

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Effects of Various Acid Etching Methods on the Shear Bond Strength between Iithium Disilicate Ceramic and Composite Resin (다양한 산처리 방법이 lithium Disilicate 도재와 복합레진간의 전단결합강도에 미치는 영향)

  • Kang, Dae-Hyun;Bok, Won-Mi;Song, Jin-Won;Song, Kwang-Yeob;Ahn, Seung-Ggeun
    • Journal of Dental Rehabilitation and Applied Science
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    • v.22 no.2
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    • pp.149-159
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    • 2006
  • Statement of problem. Porcelain repair mainly involves replacement with composite resin, but the bond strength between composite resin and all-ceramic coping materials has not been studies extensively. Purpose. The objective of this study was to investigate the influence of composite resin and ceramic etching pattern on shear bond strength of Empress2 ceramic and observe the change of microstructure of ceramic according to etching methods. Material and methods. Eighty-five cylinder shape ceramic specimens (diameter 5mm, IPS Empress 2 core materials) embeded by acrylic resin were used for this study. The ceramic were specimens divided into sixteen experimental groups with 5 specimens in each group and were etched with phosphoric acid(37%, 65%) & hydrofluoric acid (4%, 9%) according to different etching times(30s, 60s, 120s 180s). All etched ceramic surfaces were examined morphologically using SEM(scanning electron microscopy). Etched surfaces of ceramic specimens were coated with silane (Monobond-S) & adhesive(Heliobond) and built up composite resin using Teflon mold. Accomplished specimens were tested under shear loading until fracture on universal testing machine at a crosshead speed 1mm/min; the maximum load at fracture(kg) was recorded. Shear bond strength data were analyzed with one way ANOVA and Duncan tests.(P<.05) Results. Maximum shear bond strength was $30.07{\pm}2.41(kg)$ when the ceramic was etched with 4% hydrofluoric acid at 120s. No significant difference was found between phosphoric etchant group and control group with respect to shear bond strength. Conclusion. Empress 2 ceramic surface was not etched by phosphoric acid, but etched by hydrofluoric acid.

Farm Study of Direct Seeding Cultivation of the Korean Ginseng(Panax ginseng C. A. Meyer) (고려인삼의 직파재배에 관한 조사 연구)

  • Won, Jun-Yeon;Jo, Jae-Seong
    • Korean Journal of Medicinal Crop Science
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    • v.7 no.4
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    • pp.308-313
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    • 1999
  • Direct seeding is a cultivation method of Korean ginseng which can cut down production cost and increase productivity. This study was conducted to obtain detailed information about this method and to aid the development of it in Korea. Major pre-crops before ginseng cultivation were rice, corn and rye, and organic matters, such as rice straw, rye straw and poultry feces were used for basal fertilization. In direct seeding of the ginseng field, seeding density was 196 to 210 seeds per $3.3m^2$ and germination ratio was 67%. Survival ratio of 4-year-old ginsengs which were products of direct seeding was 51%, and more than 100 plants per $3.3m^2$ survived. The most critical diseases in the directly seeded ginseng field were grey mold, damping off, and stem diseases including stem spot disease. Plant growth of the ginseng cultivated by the direct seeding method was not different from the ginseng cultivated by transplanting method. But the root of the ginseng cultivated by the direct seeding method took the shape of a shorter main root compared to the ginseng cultivated by the transplanting method. Root yield per $3.3m^2$ of the direct seeding ginseng field was larger compared to the field of the transplanting cultivation.

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Analysis of RTM Process Using the Extended Finite Element Method (확장 유한 요소 법을 적용한 RTM 공정 해석)

  • Jung, Yeonhee;Kim, Seung Jo;Han, Woo-Suck
    • Composites Research
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    • v.26 no.6
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    • pp.363-372
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    • 2013
  • Numerical simulation for Resin Transfer Molding manufacturing process is attempted by using the eXtended Finite Element Method (XFEM) combined with the level set method. XFEM allows to obtaining a good numerical precision of the pressure near the resin flow front, where its gradient is discontinuous. The enriched shape functions of XFEM are derived by using the level set values so as to correctly describe the interpolation with the resin flow front. In addition, the level set method is used to transport the resin flow front at each time step during the mold filling. The level set values are calculated by an implicit characteristic Galerkin FEM. The multi-frontal solver of IPSAP is adopted to solve the system. This work is validated by comparing the obtained results with analytic solutions. Moreover, a localization method of XFEM and level set method is proposed to increase the computing efficiency. The computation domain is reduced to the small region near the resin flow front. Therefore, the total computing time is strongly reduced by it. The efficiency test is made with a simple channel flow model. Several application examples are analyzed to demonstrate ability of this method.

A SHEAR BOND STRENGTH OF RESIN CEMENT BONDED TO HUMAN UNCUT ENAMEL, CUT ENAMEL, AND DENTIN IN VITRO

  • Lee Jong-Yeop
    • The Journal of Korean Academy of Prosthodontics
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    • v.41 no.3
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    • pp.319-324
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    • 2003
  • Statement of problem. Adhesives in dentistry playa major role in the success of restorative treatments. In the treatment of all ceramic restoration it is needed to find the adequate bond strength between enamel and dentin. Purpose. The purpose of this study was to evaluate shear bond strength of resin cement bonded to extracted human uncut enamel, cut enamel, and dentin in vitro. Material and methods. Ten freshly extracted anterior teeth without any previous restorative treatments were chosen. The extracted teeth were embedded in PMMA cold acrylic in the shape of a cylinder, 25 mm in diameter by 25 mm in height. The bonding system used was as follow: Uni-Etch (32% phosphoric acid), One-Step adhesive, Duolink resin cement. The specimens were acid etched and rinsed with water. Two layers of One-Step adhesive were coated with a disposable brush on the uncut enamel. VIP curing light at $500mV/cm^2$ was used to cure the adhesive. For cut enamel shear bond test, the specimen used for uncut enamel was further reduced approximately $0.3{\sim}0.5mm$ using a laminate preparation diamond bur (0.3 mm in depth). The specimens were subsequently treated with 320-grit SiC paper followed by 600-grit SiC paper and cleaned with distilled water. The bonding procedure on the cut enamel was same as uncut enamel bonding procedure. For dentin bonding test, the specimen used for cut enamel was further reduced approximately $0.5mm{\sim}1.0mm$ using a laminate preparation diamond bur (0.5 mm in depth of diamond cutting). The amount of reduction was evaluated with the silicone mold. The specimens were subsequently treated with 320-grit SiC paper followed by 600-grit silicon carbon paper and cleaned in distilled water. The bonding procedure on the dentin was same as uncut enamel bonding procedure. All samples were mounted and secured on the Ultradent shear bond test sample holder, and Ultradent restricted shear bond testing device was used with Universal Instron machine until fracture. Analysis of variance (ANOVA) test was performed comparing the result at P<0.05. Multiple comparison (Tukey) was used to compare each groups. Result. The result showed that the mean value in shear bond strength of resin cement bonded to uncut enamel, cut enamel and dentin were 27.04 Mpa, 30.25 Mpa and 26.39 Mpa with respect. Conclusion. Within the limitation of this study, the mean value of the shear bond strength of cut enamel was higher than those of uncut enamel or dentin. However there existed no statistical differences between three different human dentition substrates due to increased adhesive characteristics.

Pin Pull Characteristics of Pin Lead with Variation of Mechanical Properties of Pin Lead in PGA (Pin Grid Array) Package (PGA (Pin Grid Array) 패키지의 Lead Pin의 기계적 특성에 따른 Pin Pull 거동 특성 해석)

  • Cho, Seung-Hyun;Choi, Jin-Won;Park, Gyun-Myoung
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.1
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    • pp.9-17
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    • 2010
  • In this study, von Mises stress and total strain energy density characteristics of lead pin in PGA (Pin Grid Array) packages have been calculated by using the FEM (Finite Element Method). FEM computation is carried out with various heat treatment conditions of lead pin material under $20^{\circ}$ bending and 50 mm tension condition. Results show that von Mises stress locally concentrated on lead pin corners and interface between lead pin head and solder. von Mises stress and total strain energy density decrease as heat treatment temperature of lead pin increases. Also, round shaped corner of lead pin decreases both von Mises stress and total strain energy density on interface between lead pin head and solder. This means that PGA package reliability can be improved by changing the mechanical property of lead pin through heat treatment. This has been known that solder fatigue life decreases as total strain energy density of solder increases. Therefore, it is recommended that both optimized lead pin shape and optimized material property with high lead pin heat treatment temperature determine better PGA package reliability.

Induction Heating of Cylinderical MoSi2-based Susceptor (실린더형 MoSi2계 발열체의 유도가열 적용)

  • Lee, Sung-Chul;Kim, Yo Han;Myung, Jae-ha;Kim, Bae-Yeon
    • Korean Chemical Engineering Research
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    • v.57 no.4
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    • pp.553-558
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    • 2019
  • In present study, the cylindrical susceptor by the slip casting method was designed to apply high-temperature induction heating by using $(Mo,W)Si_2$ ceramics. $MoSi_2$-based materials were synthesized by SHS (Self-propagating High-temperature Synthesis) method. The phase and crystal structure of $MoSi_2$-based materials were confirmed by XRD analysis. The shape of cylindrical mold was synthesized for various thickness by using the slip casting method. Finally, the susceptor for induction heating was processed by sintering and heat treatment to form $SiO_2$ layer, which was confirmed on the surface of susceptor by SEM/EDS analysis. To evaluate the heating performance of $(Mo,W)Si_2$ cylinder susceptor, we measured the maximum surface temperature and heating rate in comparison with the rod heating element under constantly applied power. The induction heating of the $(Mo,W)Si_2$ cylinder showed excellent heating performance, reaches the maximum temperature of $1457^{\circ}C$, with the average heating rate of $19^{\circ}C/s$ at 2 kW

Numerical Approach to Optimize Piercing Punch and Die Shape in Hub Clutch Product (허브클러치 제품의 피어싱 펀치 및 금형 형상 최적화를 위한 수치접근법)

  • Gu, Bon-Joon;Hong, Seok-Moo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.517-524
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    • 2019
  • The overdrive hub clutch is attached to a 6-speed automatic transmission to reduce fuel consumption by using the additional power of the engine. This paper proposes a means to minimize the load and roll-over ratio on the punch during the piercing process for the overdrive hub clutch product. Die clearance, shear angle, and friction coefficient, which can affect the load and roll-over ratio of the punch during processing, were set as the design variables. Sensitivity analysis was also conducted to determine the influence of each design variable on the punch load and roll-over ratio. As a result, shear angle, friction coefficient and die clearance were found to be sensitive to load and roll-over ratio. The punch load and roll-over ratio were set as the objective function and the equation of each design variable and objective function was derives using the Response Surface Method. Finally, the optimal value of the design variables was derived using the Response Surface Method. Application of this model to finite element analysis resulted in 22.14% improvement in the roll-over ratio of the punch load and material.

'Arihyang', a Strawberry Variety with Highly Firm and Large-Sized Fruit for Forcing Culture (촉성재배용 고경도 대과성 딸기 품종 '아리향')

  • Kim, Dae-Young;Kim, Seung Yu;Huh, Yun-Chan;Yoon, Moo Kyung;Lee, Sun Yi;Moon, Ji-Hye;Kim, Dae Hyun
    • Korean Journal of Breeding Science
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    • v.50 no.4
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    • pp.497-503
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    • 2018
  • A strawberry variety 'Arihyang' was derived as an artificial cross between 'Tochiotome' and 'Seolhyang' in 2014. The seedling and line selections were conducted from 2014 to 2015. Preliminary and advanced yield trials of '14-5-5,' which was the final selected line, were conducted from 2015 to 2017. 'Arihyang' is suitable for forced cultivation and has strong plant vigor, uniformly large-sized fruit, and a high yield compared to those of the check variety, 'Seolhyang' and 'Maehyang.' Especially, vitamin C was at a significant level, which was approximately 15% higher than that of 'Seolhyang.' The average number of flowers per first flower cluster was 10.5, which could reduce the labor of thinning fruit. Its fruit has a conical shape, dark red color, and glossy skin. The fruit was of good quality but has recommendations for harvest at the fully ripened stage. 'Arihyang' has intermediate resistant to phytophthora crown rot, but is susceptible to powdery mildew, gray mold, anthracnose, and fusarium wilt. It is reguired to manage major diseases and pests using optimum cultivation techniques and chemical control.

The A Literary Investigation on Mandu (Dumpling);Types and Cooking Methods of Mandu (Dumpling) During the Joseon Era (1400's${\sim}$1900's) (만두의 조리방법에 대한 문헌적 고찰;조선시대 만두의 종류와 조리방법에 대한 문헌적 고찰(1400년대${\sim}$1900년대까지))

  • Bok, Hye-Ja
    • Journal of the Korean Society of Food Culture
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    • v.23 no.2
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    • pp.273-292
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    • 2008
  • Among all the ingredients usedin mandu, the following types were used:, 13 types of grains were used (12.38%), 30 types of vegetables, fruits, bulbs,and nuts were used (28.57%), 32 types of marine products, birds, meats, fishes, and shellfishes were used (30.48%), 10 types of functional ingredients were used (9.52%) and. For spices, 20 types of spices were used (19.05%). 2. Cooking Methods offor Mandu. The mMandu eaten at in the early Joseon era had was primarily made ofusedbuckwheat that contained boiled tofu or egg uiijuk in the kneaded dough for the most part and while kneading with buckwheat, the tofu or egg uiijuk has been boiled down to knead the dough, and and starch powder, bean powder, or rice powder, etc were mixed to make the mandu coating. Buckwheat powder was mixed toadded to the flourwer or was used by itself, while meat, vegetables, tofu, and shiitake mushroom, etc were also addedincluded. From the 18th century, the host plant, or cabbage kimchi, were prepared and combined had been sliced to be used as filling together while red pepper powder was mixed combined withto spices or vinegar soy sauce to be used together. Also, Radishes had beenwere also used as filling, but shown as not being used fromafter the start of the 1900's. For the shape of mMandu, it was madeinto different shapes such as as triangle, rectangle, date plum, gwebul, half moon, or pomegranate shapes, and then shapes to be boiled in simmering water, baked, or cooked as soup in clear broth for soup., In the 17th to 18th century, boilingthen in a steamer gradually became a cooking style, assumed the style of boiling in a steamer in $17th{\sim}18th$ century while in the 16th century,the an essay ofn fermenting flour in ‘Food Dimibang’ in 16th century had indicated it was cooked as the style ofby steaming in a rice steamer. Also, Mandu may have also contained the following: the thin-cut and boiled fish was cut out thin to put into the filling and boiled down, made by putting in added pine nuts after making bbeef jerky or boiled- down meat, fish, or shellfish itself to extractsand mold mandu only the ingredients combined withto put on starch powder, and then boiled down and put on pine nut powder finally, after it or cooled it wasdown to be eaten by dipping in vinegar soy sauce. In conclusion, many different types of mandu were made during the Joseon era using a variety ofwhile the ones using such various ingredients. are also one type of mandu.

Structural analysis of Precipitates in a Nickel based Cast Single Crystal of CMSX 6 (니켈계 초합금 CMSX 6 단결정 주조조직의 석출물구조 분석)

  • An, Seong-Uk;Larionov, V.;Grafas, I.;Kim, Su-Cheol;Im, Ok-Dong;Kim, Seung-Ho;Jin, Yeong-Hun;Choe, Jong-Su;Lee, Jae-Hun;Lee, Sang-Jun;Seo, Dong-Lee;Lee, Tae-Hun;Heo, Mu-Yeong
    • Korean Journal of Materials Research
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    • v.8 no.12
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    • pp.1165-1169
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    • 1998
  • A single crystal cast blade was manufactured by CMSX 6, one of the first generarion nickel based single crystal superalloys by the selector method in a vacuum furnace. The single crystal has been grown with cooling rate of 2.5 mm/min, after pouring the molten alloy of 163$0^{\circ}C$ to the mold heated to 150$0^{\circ}C$. The cast structure could be classified into matrix (dendrite) and eutectic regions in ${\gamma}$'shape and size. The eutectic region showed higher Ti content. As the additional results of ${\gamma}$'precipitates by EPMA and CBED analysis the ${\gamma}$'size was less than 0.5~0.7$\mu\textrm{m}$, showing the chemical composition close to Ni$_3$Al of Ll$_2$ lattice structure. But ${\gamma}$'size has increased to bigger than 1.0$\mu\textrm{m}$, being near to eutectic region, changing its shape to bar or huge block types. These showed the chemical structure near to Ni$_3$Ti of D $O_{24}$ lattice structure. Therefore, ${\gamma}$'morphology of dendrite and eutectic regions depends absolutely on its chemical composition and lattice structure.

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