• The Journal of Advanced Prosthodontics
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• 제10권2호
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• pp.122-127
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• 2018

PURPOSE. This study evaluated the dimensional stability of a complete-arch prosthesis processed by conventional method in water bath or microwave energy and polymerized by two different curing cycles. MATERIALS AND METHODS. Forty maxillary complete-arch prostheses were randomly divided into four groups (n = 10): MW1 - acrylic resin cured by one microwave cycle; MW2 - acrylic resin cured by two microwave cycles: WB1 - conventional acrylic resin polymerized using one curing cycle in a water bath; WB2 - conventional acrylic resin polymerized using two curing cycles in a water bath. For evaluation of dimensional stability, occlusal vertical dimension (OVD) and area of contact points were measured in two different measurement times: before and after the polymerization method. A digital caliper was used for OVD measurement. Occlusal contact registration strips were used between maxillary and mandibular dentures to measure the contact points. The images were measured using the software IpWin32, and the differences before and after the polymerization methods were calculated. The data were statistically analyzed using the one-way ANOVA and Tukey test (${\alpha}=.05$). RESULTS. The results demonstrated significant statistical differences for OVD between different measurement times for all groups. MW1 presented the highest OVD values, while WB2 had the lowest OVD values (P<.05). No statistical differences were found for area of contact points among the groups (P=.7150). CONCLUSION. The conventional acrylic resin polymerized using two curing cycles in a water bath led to less difference in OVD of complete-arch prosthesis.

• Restorative Dentistry and Endodontics
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• 제17권1호
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• pp.69-82
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• 1992

An experimental investigation of the physical properties of light curing composite resin P-50 was performed, in which an argon ion laser beam was irradiated. The physical and mechanical properties of laser polymerized composite resin were determined by measuring the compressive strength, diametral tensile strength, curing depth and microhardness depending upon the experimental conditions such as the laser irradiation time(10sec, 20sec, 30sec) and laser power(300mW, 500mW, 1000mW). These observations were compared with a conventional visible light curing technique. In addition, to evaluate the marginal adaptation, Class V cavity was prepared on the buccal or lingual surface of the extracted premolar and filled with P-50 light curing resin. The test samples were irradiated with both light sources so that the interface between the restoration and the tooth structure were observed under scanning electron microscope. The most of physical and mechanical properties of the laser cured resin showed a remarkable improvement than those treated with the conventional light source, while the observations with the scanning electron microscope provided no significant difference for two polymerized sources. From the results in the experiment it appears that the potential of an argon ion laser is of important value of the use in the polymerization of composite resin.

• 대한치과기공학회지
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• 제42권4호
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• pp.341-347
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• 2020

Purpose: This study aimed to evaluate the effect of post-curing method on the flexural strength of provisional restorative resins produced by a digital light processing printer. Methods: A total of 20 specimens were produced, with a length of 64 mm, width of 10 mm, and thickness of 3.3 mm using a digital light processing printer. Two types of provisional restorative resins made with different post-curing methods were investigated and divided into conventional and vacuum groups. For the flexural strength test, each group was prepared by each method according to ISO 10477, and the flexural strength was measured with a universal testing machine. For statistical analysis, data were analyzed by independent t-test and Mann-Whitney U test. Results: The flexural strengths of the conventional and vacuum groups were 151.89 MPa and 131.94 MPa, respectively, showing a statistically significant difference (p<0.05). Conclusion: Within the limitation of this study, provisional restorative resins produced with vacuum demonstrated lower flexural strength than those produced with conventional postcuring method.

• 대한소아치과학회지
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• 제32권2호
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• pp.332-343
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• 2005

본 연구에서는 기존의 할로겐 광중합기를 이용하여 40초간 조사하여 복합레진을 중합한 경우와 플라즈마 광중합기를 이용한 고강도의 중합 및 완속기시 중합 방식, 그리고 LED 광중합기를 이용한 통법의 중합과 완속기시 중합 방식으로 복합레진을 중합하여 발생되는 수축응력을 비교하고 미세경도를 측정하여 중합도를 평가하였다. 내경 7mm, 외경 10mrn의 아크릴릭 주형을 제작하고 외면에 스트레인게이지를 부착시킨 뒤 각각의 광원에 따른 중합모드로 광중합 하였다. 광조사 시점부터 1초 간격으로 600초간 수축응력을 측정하였으며, 중합 24시간 후 각 군의 미세경도를 측정하여 통계 분석하였다. 수축응력 측정 후 시편을 종단하여 주사전자현미경으로 레진수복물과 아크릴릭 주형 계면을 관찰하였다. 이상의 실험을 통해 얻은 결과는 다음과 같다. 1. 플라즈마 광과 LED 광원의 완속기시 중합방식은 각각의 기본 중합방식에 비해 중합 10분 후에 수축응력 감소를 보였다(P<0.05). 2. 완속기시 중합방식의 플라즈마 광이 가장 낮은 수축응력을 보였으나 미세경도 또한 가장 낮았다(P<0.05). 3. 완속기시 중합방식의 LED 광중합은 기존의 할로겐 광과 LED 광중합 방법에 비하여 낮은 수축응력을 보였다(P<0.05). 4. 완속기시 중합방식의 LED 광으로 조사한 시편의 미세경도는 단일광도로 조사한 할로겐 광과 LED 광중합과 비교하여 유의할만한 차이가 나타나지 않았다(P>0.05). 5. 기존의 할로겐 광과 완속기시 중합방식의 LED로 중합한 시편이 플라즈마 광과 단일강도의 LED로 조사한 군보다 더 나은 변연봉쇄를 보였다.

• Macromolecular Research
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• 제13권2호
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• pp.120-127
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• 2005

Conventional poly(methyl methacrylate) (PMMA) bone cement has been widely used as an useful biopolymeric material to fix bone using artificial prostheses. However, many patients had to be reoperated, due to the poor mechanical and thermal properties of conventional PMMA bone cement, which are derived from the presence of unreacted MMA liquid, the shrinkage and bubble formation that occur during the curing process of the bone cement, and the high curing temperature ($above 100^{\circ}C$) which has to be used. In the present study, a composite PMMA bone cement was prepared by impregnating conventional PMMA bone cement with ultra high molecular weight polyethylene (UHMWPE) powder, in order to improve its mechanical and thermal properties. The UHMWPE powder has poor adhesion with other biopolymeric materials due to the inertness of the powder surface. Therefore, the surface of the UHMWPE powder was modified with two kinds of silane coupling agent containing amino groups (3-amino propyltriethoxysilane ($TSL 8331^{R}$) and N-(2-aminoethyl)-3-(amino propyltrimethoxysilane) ($TSL 8340^{R}$)), in order to improve its bonding strength with the conventional PMMA bone cement. The tensile strengths of the composite PMMA bone cements containing $3 wt\%$ of the UHMWPE powder surface-modified with various ratios of $TSL 8331^{R}$ and $TSL 8340^{R}$ were similar or a little higher than that of the conventional PMMA bone cement. However, no significant difference in the tensile strengths between the conventional PMMA bone cement and the composite PMMA bone cements could be found. However, the curing temperatures of the composite PMMA bone cements were significantly decreased.

• 한국연초학회지
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• 제21권2호
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• pp.182-187
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• 1999

A bulk curing experiment was carried out to evaluate the effect of air flow reduction in the bulk barn from color fixing stage in the chemical properties of cured leaves, The air flow was controlled by reducing air velocity of a blower from 0.3m/sec to 0.2m/sec using a boltage regulator(Slidac). The bulk curing before color fixing stage was processed in the conventional curing method. Reduction of air circulation in bulk barn did not affected so much on change of the contents of the main chemical components in cured leaved, such as nicotine, total sugar, total nitrogen, petroleum ether extract, and organic acids. Only a slight increase in essential oil contents, such as solanone, damascenone, damascone, $\beta$-ionone, and megastigmatrienone isomer, could be observed in leaves cured in the reduced air flow.

• 한국도로학회논문집
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• 제19권2호
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• pp.67-74
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• 2017

PURPOSES : The objective of this study is to ascertain the curing period of cementless cold central plant recycled asphalt base-layer, using mechanical analyses and specimen quality tests on the field. METHODS : Cold central plant recycled asphalt base-layer mixture was produced in the plant from reclaimed asphalt, natural aggregate, filler for the cold mix, and the modified emulsion AP using asphalt mix design and plant mix design. In order to examine the applicability of the curing period during the field test, the international standards for the possibility of core extraction and the degree of compaction and LFWD deflection were analyzed. Moreover, Marshall stability test, porosity test, and indirect tensile strength test were performed on the specimens of asphalt mix and plant mix design. RESULTS : The plant production process and compaction method of cementless cold central plant recycled asphalt base-layer were established, and the applicability of the optical moisture content for producing the mixture was verified through the field test. In addition, it was determined that the core extraction method of the conventional international curing standard was insufficient to ensure performance, and the LFWD test demonstrated that the deflection converges after a two-day curing. However, the back-calculation analysis reveals that a three-day curing is satisfactory, resulting in a general level of performance of dense asphalt base-layer. Moreover, from the result of the specimen quality test of the asphalt mix design and plant mix design according to the curing period, it was determined that the qualities satisfied both domestic and international standards, after a two-day curing. However, it was determined that the strength and stiffness after three-day curing are higher than those after a two-day curing by approximately 3.5 % and 20 %, respectively. CONCLUSIONS:A three-day curing period is proposed for the cementless cold central plant recycled asphalt base-layer; this curing period can be demonstrated to retain the modulus of asphalt-base layer in the field and ensure stable quality characteristics.

• 대한소아치과학회지
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• 제29권1호
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• pp.19-29
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• 2002

본 연구의 목적은 다양한 중합과정에 따른 복합레진과 컴포머의 수축 양상을 스트레인 게이지법(strain gauge method)을 이용하여 평가해보고자 하는 것이었다. 광중합기는 기존의 할로겐 시스템인 XL 3000(3M, USA)과 최근 소개된 plasma arc curing 시스템인 Flipo(LOKKI, France)를 사용하였고, 충전 재료는 복합레진인 Z-100(3M, USA)과 컴포머인 Dyract AP(Dentsply, Germany)를 사용하였다. 주형과 치아 와동 내에 충전된 실험재료의 중합수축을 각각 측정하였으며, 만능시험기를 이용하여 압축강도를 측정하였다. 중합수축 측정 결과 모두 중합초기에는 일시적인 재료의 팽창을 나타냈고, 그 후 약 1분간은 수축량이 급격히 증가하다가 증가의 폭이 점차 감소하는 양상을 보였다. 전반적으로 컴포머를 사용한 군에 비해 복합레진을 사용한 군에서 중합수축이 크게 나타났으며 plasma arc curing 시스템을 사용한 군에 비해 기존의 광조사 시스템 군에서 더 큰 중합수축을 보였다. 압축 강도의 측정결과는 컴포머 군에 비해 복합레진 군에서 크게 나타났다. 이상의 결과를 종합해 볼 때, plasma arc curing unit와 컴포머의 사용은 시술시간의 단축과 항우식 효과를 감안한다면 소아치과 영역에서의 사용이 긍정적으로 고려될 수 있다고 생각된다.

• 한국응용과학기술학회지
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• 제29권1호
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• pp.159-173
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• 2012

UV 경화기술은 라디칼 경화와 양이온 경화로서 크게 2 종류로 분류할 수 있다. 이 기술은 플라스틱과 금속간의 여러 기재에 대한 기능성을 개선하기 위해서 표면처리기술에 주로 초점이 맞추어져 왔다. 반면에, Electron beam 기술은 새로운 기능성 재료들을 창출하기 위해 중합공정뿐만 아니라 가교반응들을 다루었다. 이들 두 기술들은 종래의 열경화성 코팅과 비교할 때, 에너지이용 효율과 환경 친화적이어서, 건조와 경화 공정으로 부터 배출되는 탄산가스와 휘발성 유기물을 대폭 감소시킨다. 이 논문에서는 UV 경화 코팅에서 흔히 사용되는 라디칼 경화기술과, 최근의 있는 양이온 경화와 관련된 기술을 다룬 리뷰 논문이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.525-528
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• 2006

Recently, Korea government prepared Act on facilitation of construction waste recycling in December 2003 for effective recycling of rapidly increasing construction wastes, and has enforced the Act on Jan. 2005. This Act limits the definition of recycled aggregates to the aggregates which obtained quality certificate and for this purpose, government has operated quality standard and certificate system of recycling aggregate. The objective of this experimental study is to evaluate the mechanical properties of recycled coarse aggregate concrete according to curing method by ready-mixed concrete. Compressive strength ratio of recycled aggregate concrete under air-dry curing/wet curing was $74{\sim}91%$. KCI code for conventional concrete overestimated elastic modulus for recycled coarse aggregate concrete.