• The Journal of Advanced Prosthodontics
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• 제2권3호
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• pp.102-105
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• 2010

PURPOSE. The aims of this study were to suggest a method of fabrication of the record base using a light-polymerized resin by applying the two-phase fabrication method for the improvement of the fit of the record base and to compare the degree of fit according to the separation site. MATERIALS AND METHODS. In the edentulous cast of maxilla, four test groups were considered. In the first, second, third, and fourth test groups (n = 12 in each group) the separation was done at 0, 5, 10, and 15 mm, respectively below the alveolar crest along the palatal plane. For the control group, the record base was made without separating the two sections. The light-body silicone material was injected into the fitting surface of the record base. It was then placed onto the cast and finger pressure was applied to stabilize it in a seated position followed by immediate placement onto the universal test device. Finally, the mass of the impression material was measured after it was removed. ANOVA was performed using the SAS program. For the post-hoc test, the Wilcoxon Rank-Sum test and the Tukey-Kramer HSD test were performed ($\alpha$ = 0.05). RESULTS. The control group and Group 3, 4 showed significant differences. The Group 3 and 4 showed significantly smaller inside gaps than the control group which was not made with the two-phase fabrication method. CONCLUSION. The two-stage polymerized technique can improve the fit of the denture base particularly when the separation was made at 10 to 15 mm from the alveolar crest.

• 한국염색가공학회지
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• 제22권3호
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• pp.187-193
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• 2010

The effects of molecular weight (MW) and concentration on the rheological properties of poly(vinyl alcohol) (PVA) solutions in dimethyl sulfoxide (DMSO) were investigated at $30^{\circ}C$. Ubbelohde viscometer and rotational rheometer were employed for dilute and concentrated regime, respectively. In the dilute regime, the Mark-Houwink exponent ($\alpha$) of the solutions determined from three different MWs proved 0.73. The critical concentration (C*), in which the entanglement and overlap of polymer molecules began to take place, decreased with increasing the MW of PVA. Huggins constant ($K_H$) values ranged from 0.33 to 0.45 over the MW examined. In the log-log plot of $\eta_{sp}$ versus [$\eta$]C, the PVA with higher degree of polymerization (DP) gave a greater slope exhibiting the inflection point in the vicinity of C*. In the dynamic viscosity ($\eta'$) curve, the PVA solutions of DP 1700 presented Newtonian fluid behavior over most of the frequency range examined. However, the lower Newtonian flow region reduced with increasing the DP. As the PVA concentration increased, $\eta'$ was increased and the onset shear rate for pseudoplasticity was decreased. In the Cole-Cole plot, PVA solutions showed almost a single master curve in a slope of ca. 1.65 regardless of the DP. However, the increase of the concentration from 8 to 12 wt% for PVA solutions of DP 5000 decreased the slope from 1.73 to 1.57. In the tan $\delta$ curve, the onset frequency for sol-gel transition was shifted from 154 to 92 rad/s with increasing the DP from 3300 to 5000 and from 192 to 46 rad/s with increasing the concentration from 8 to 12 wt%. In addition, longer relaxation time ($\lambda$) was observed with increasing the DP and concentration.

• 패션비즈니스
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• 제12권6호
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• pp.107-123
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• 2008

The purpose of this research is to compare and analyze the brassiere patterns sold in Shanghai and Korea and to present basic materials needed in developing the brassiere patterns in Chinese adult women market. The study subject which is to find the difference in brassiere patterns of Korea and China has been selected of 3 Korean brands and 4 Chinese brands. 1. For the brassiere patterns sold in Korea, it were using the same size for the width of Hook&Eye, space between the shoulder lace on the back, slope of wing and the location of the Keeper was similar. 2. For the cup supporting base, Chinese brassiere covers the lower part of the breast and as it is not comfortable and has a phenomenon of loosening up, there were severe puckering. For issues in the wearing experiment, amendments in patterns with the cup part was required. 3. Chinese brassieres were big differences in wing angles and for Aimer, it had the steepest trend in wings and thus the wings headed down and for Gujin, as the angle of the wing was smaller than $90^{\circ}$, it was heading upward. 4. Upon comparing the patterns of the Korean and Chinese brassiere, although most of the sizes excluding the wing angle had similar sizes, there was big differences in the wing angle. The reason why the brassiere patterns sold in China had bigger wing angle was due to the fact that more Chinese women had sway back body type than the Korean women and should reflect such difference in body size into making the brassiere patterns for each women.

• Applied Microscopy
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• 제28권2호
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• pp.193-205
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• 1998

The Urechis unicinctus sperm and spermatogenic cells prepared from the testis are investigated to identify $\alpha-tubulin$ of axoneme microtubules using mouse monoclonal $anti-\alpha-tubulin$ as the first Ab and Gold(10nm) conjugated goat anti-mouse IgG as the Ab marker. The Ag-Ab reaction analyzed excellently the localization of $\alpha-tubulin$ and the gold particles incorporated with the proximal and distal centrioles, manchette microtubules, and flagellum. The gold particles can be also observed in the spermatogenic cells while the cells are still in sperm ball which is composed of a somatic cell and spermatogenic cells. The sperm ball is the functional unit of sperm production in U unicinctus testis. The spermatids are developed from the spermatogenic cells in the sperm ball and released into the testis cavity through a cortical cytoplasmic opening. The spermatid architectures are similar with the mature sperm of the testis cavity in aspects of shape of discoid acrosome, degree of nuclear condensation and ring type of mitochondrion. However, the distal centriole connecting with the flagella can be observed from the mature sperm while the both proximal and distal centrioles reveal only in the spermatids. The proximal centriole is directly connected with nuclear outer membrane during the stage of nuclear condensation and oriented perpendicularly to the distal centriole whose axis coinciding with the longitudinal axis of the spermatozoon. There are indications that the distal centriole is intimately associated with the polymerization of the flagellum. The manchette microtubules appear during spermatid development but the mature sperm have round head and no conspicuous middle piece.

• 생명과학회지
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• 제19권4호
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• pp.457-461
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• 2009

본 연구는 Lipomyces starkeyi KCTC 17343에 의한 dextranase 최적 생산 조건을 확립하고 dextran에 대한 효소 분해 특성을 규명하였다. 균주의 성장과 dextranase생산은 발효초기 pH와 온도에 따라 다르며 최적 pH는 4-5, 최적온도는 $25-30^{\circ}C$의 범위에서 결정이 되었다. 최적 발효조건에서의 dextranase 생산은 total enzyme activity가 4.85 IU/ml으로 나타났다. 이때의 발효균주의 specific growth rate는 $0.076h^{-1}$이었다. 발효 중 dextranase의 활성은 발효 정상기에서도 안정성을 유지하였다. Dextranase에 의한 dextran을 가수분해 결과, 가수분해물의 구성은 DP2 to 8에 이르는 올리고 덱스트란으로 이루어졌다.

• 공업화학
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• 제7권5호
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• pp.843-848
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• 1996

현탁중합에 의하여 다공성 스티렌-디비닐벤젠 공중합 수지입자를 제조하였으며, 그 수지입자는 가교제인 디비닐벤젠과 세공형성제인 톨루엔 농도가 각각 30wt% 이상일 때만 다공성을 나타내었다. 다공성 수지입자의 비표면적은 디비닐벤젠과 톨루엔의 농도에 따라 증가하였으며, 진한 황산으로 황산화시켰을 때 비표면적은 감소하였다. 에틸아세테이트와 1-프로판올의 에스테르화 반응에서 황산화된 수지촉매의 활성은 가교도에 따라 증가하였다. 수용액 중 sodium dodecylbenzene sulfonate의 흡착에서 다공성 수지입자의 표면적에 따라 흡착량이 증가하였다.

• 공업화학
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• 제10권1호
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• pp.1-5
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• 1999

알킬비닐에테르와 말레인산디에틸에스테르의 공중합체인 측쇄알킬기의 탄소수나 중합도가 다른 올리고머형 음이온성 계면활성제 ($C_mD-Na$)를 분산제로 사용하고 친수성 안료로서 산화철이나 산화티탄의 미립자에 대한 분산성을 비교검토하였다. 그 결과 올리고머형 계면활성제의 동족체는 안료입자 표면에 알킬기가 흡착되므로써 흡착층을 형성하고 있는 입자에 음의 하전을 띠어 분산거동이 다르지만, $C_4D-Na$는 저농도에서도 우수한 분산능을 나타내었다. 그리고 소수성인 ${\alpha}-Fe_2O_3$와 Anatase $TiO_2$는 0.1% 농도 이상의 범위에서도 측쇄알킬기의 탄소수가 $C_8$ 이상인 것이 분산작용에 양호한 것으로 나타났다.

• 한국재료학회지
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• 제30권1호
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• pp.38-43
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• 2020

Sand casting 3D printing uses a binder jetting method to produce a mold having complicated shape by spraying a binder on sand coated with activator. Appropriate heat treatment process in sand mold fabrication can increase the degree of polymerization to improve flexural strength. However, long heat treatment of over 24 hours decreases flexural strength and reliability due to chemical bond decomposition through thermal degradation. The main role of the activator is to control the reaction rate between the polymer chains. As a result, when the activator composition is increased from 0.15 wt% to 0.25 wt%, the flexural strength is increased by 218 N/㎠. However, excess activator (0.40 wt%) has been shown to decrease reliability without increasing flexural strength. The main role of the binder is to control the flexural strength of the specimen. As the binder composition is increased from 2.00 wt% to 4.00 wt%, the flexural strength increases to about 255 N/㎠, indicating the maximum flexural strength increase. Finally, the reliability of the flexural strength of the fabricated specimens is evaluated by a Weibull plot. Weibull modulus calculations are used to evaluate the flexural strength reliability of the specimens, and maximum reliability value of 11.7 is obtained at 0.20 wt% activator composition. Therefore, it is confirmed that this composition has maximum flexural strength reliability.

• 폴리머
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• 제36권5호
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• pp.579-585
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• 2012

고분자 발포체에 전도성을 부여하기 위하여 고내상 에멀젼 중합법을 활용하여 폴리스티렌/탄소나노튜브 미세기공 발포체를 제조하였다. 본 연구에서는 고내상 에멀젼의 안정성과 중합된 미세기공 발포체의 전기 전도도를 향상시키기 위하여 탄소나노튜브의 개질, 계면활성제의 함량 및 분산 시간에 따른 영향을 고찰하였다. 탄소나노튜브는 분산이 용이하도록, 분산상인 수상에는 산처리 및 계면활성제로 분산하여 사용하였고 연속상인 유상에는 유기 작용기로 표면 개질하여 사용하였다. 탄소나노튜브의 분산성은 제조한 발포체의 전기 전도도 차이로 확인할 수 있었다. 계면활성제로 분산한 미처리 탄소나노튜브를 수상에 첨가한 경우 전기 전도도 향상에는 효과적이었지만 약간 수축된 형상의 발포체가 제조되었다. 유기 개질한 탄소나노튜브를 유상에 첨가한 경우 안정한 발포체를 얻을 수 있었으나 전기 전도도 향상에는 한계가 있었다.

• 대한화학회지
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• 제19권3호
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• pp.198-206
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• 1975

갇광성 관능기를 갖는 중합체, 이를테면 polyglyceryl phthalate(PG), bisphenol A-epichl-orohydrin 축중합체(BE) 및 polyvuinyl alcohol(PVA)의 naphthoquinone-1,2-diazide-5-sulfonyl esters(PGND, BEND 및 PVAND)를 합성하였다.빙점강하법으로 측정한 모체수지들의 분자량은 PG의 경우 650${\sim}$1500, BE는 780${\sim}$1320이었다. PG, BE 및 PVA를 naphthoquinone-1,2-diazide-5-sulfonyl chloride로 ester화 시켜 얻은 PGND, BEND 및 PVAND의 원소분석의 계산치와 실측치가 잘 일치하고 있는 점으로 보아 모체수지인 PG, BE 및 PVA의 중합도는 ester화 된 경우에도 변하지 않는다는 것을 알 수 있었다.