• 접착 및 계면
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• 제12권2호
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• pp.67-72
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• 2011

Acrylic pressure-sensitive adhesives are used in many different parts in the world. But acrylic acid in PSAs may occur unexpected results such as corroding adherends or producing by-products when applied within electronic devices. This study employed acrylic PSAs based on 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl acrylate (2-HEA) and butyl acrylate (BA) with different coating thickness. There are two types of curing agents. One is methylaziridine derivative (MAZ) and the other is aluminum acetylacetonate (AlACA). This study examined the adhesion performance and curing behaviors using peel strength, probe tack and gel fraction. Also, the viscoelastic properties of acrylic PSAs were investigated from Advanced rheometric expansion system (ARES).

• 구강회복응용과학지
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• 제16권3호
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• pp.221-227
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• 2000

Provisional fixed partial dentures(FPDs) are an important part of many prosthodontic treatment procedures. These provisional fixed prostheses must fulfill biologic, mechanical, and esthetic requirements to be considered successful. Consideration of all these factors and requirements are important because provisional resin restorations may be worn over a long period to assess the results of periodontal and endodontics therapies, and also during the restorative phase of implant reconstructive procedures. This in vitro study examined flexual strength of four resins commonly used for fixed provisional prostheses. The effects of polymerization conditions were also evaluated. The four resins tested were : Caulk Temporary bridge resin(L.D. Caulk Co. Dentsply International Millford), Jet(Lang Dental Mfg. Co. Chicago. ILL. U.S.A), Alike (Coe Laboratories. Inc. Chicago. ILL. U.S.A) and Tokuso Curefast (Coe Laboratories. Inc. Chicago. ILL. U.S.A) The test specimens were 65mm long, 14mm wide, and 3.5mm thickness. 10 specimens of four resins were cured for 15 minutes at atmospheric pressure and 10 specimens of four resins were cured at an additional pressure of approximately 20 psi. A total of 80 specimens were prepared. The flexual strength was determined by three-point bending test. Data were analysed with the Paired samples T-test and Tukey student-range test Within the limitations imposed in this study, the following conclusions can be drawn : 1. Under the condition of bench curing, Caulk Temporary bridge resin showed the highest flexual strength. In decreasing order, the flexual strength of the other materials was as follows : Jet, Tokuso Curefast, Alike, and Caulk Temporary bridge resin demonstrated significantly higher strength than other resins. 2. Under the condition of pressure curing, Jet showed the highest flexual strength. In decreasing order, the flexual strength of the other materials was as follows : Caulk Temporary bridge resin, Tokuso Curefast, and Alike. There were all statistically significant differences among four resins 3. There was a statistically significant difference between bench- and pressure-cured specimens in all four materials.

• 한국지반환경공학회 논문집
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• 제13권11호
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• pp.61-68
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• 2012

지반보강을 위해 국내에서 널리 사용되고 있는 공법으로 앵커공법, 소일네일 공법 및 소구경말뚝 공법 등을 들 수 있다. 상기 공법의 경우 보강재의 시공은 용도에 따라 구분되지만 공통적으로 보강재를 삽입한 후에 그라우팅 작업을 실시하는 공정이 포함되어 있다. 지금까지는 국내 대부분의 경우 중력식 그라우팅으로 시공되고 있지만 중력에 의해 그라우팅을 실시하기 때문에 천공 시 발생하는 지반이완영역에 대한 복원이 명확지 않아 보강재의 구조적 결함을 유발할 우려가 있다. 반면에 압력재주입 그라우팅은 먼저 그라우트를 채운 후 소정의 시간이 지나고 미리 설치한 튜브를 통하여 추가적으로 재주입하는 방식으로 기존의 그라우팅 방식에서 발생할 수 있는 문제를 상당부분 해결할 수 있어 그라우팅의 품질을 향상할 수 있다. 본 연구에서는 그라우팅 방식에 따른 인발특성을 평가하기 위하여 화강풍화토 지반을 대상으로 모형실험을 실시하였으며, 그라우팅방법에 따른 인발력 변화와 압력 재주입그라우팅의 재주입시기와 재주입압에 따른 보강재 지지력 증대 특성을 평가하고자 하였다. 연구결과 압력재주입식 그라우팅이 중력식그라우팅에 비해 최소 1.1배에서 1.3배까지 인발력이 크게 발휘되는 것을 확인하였으며, 압력재주입식 그라우팅의 적정 물시멘트비, 주입압력 및 재주입시기에 대한 고찰결과를 제시하였다.

• 대한기계학회논문집
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• 제18권7호
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• pp.1773-1782
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• 1994

In this paper, the expert cure system for carbon fiber epoxy composite materials, which controls the temperature and pressure of the autoclave according to the several rules, was developed to manufacture better composite products in shorter curing time. The rules were based on the on-line measured quantities such as the dielectric properties and temperature of the composites and the pressure of the autoclave. The curing time and the mechanical properties of the composite materials manufactured with the expert cure system were compared to those of the specimens manufactured with the conventional cure cycle.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.49-56
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• 1999

A material was formulated with Phenol novolac and HEXA only. The cure kinetics and thermal characteristics of phenol novolac with various HEXA contents were peformed by differential scanning calorimetry and thermal gravimetric analysis. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicate that the curing reaction goes through an autocatalytic kinetic mechanism. The friction and wear characteristics of this material were determined using friction material testing machine. The friction coefficient of phenol novolac with various HEXA contents was determined using the PV(pressure & velocity) factor. The most stable and highest friction coefficient with a various pressure and velocity condition was found at HEXA 10 wt.% material. The specific wear rate per unit sliding distance with a various HEXA contents was reported.

• 대한치과보철학회지
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• 제34권4호
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• pp.665-674
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• 1996

This study was designed to evaluate the effect of processing method and surface design on the transverse strength of repaired denture base resin. Three heat-cured denture base resins(Vertex, Lucitone, Lang), one cold-cured resin(Lang), and one light-cured resin(Dentacolor gingiva material) were used for repair purpose. The specimens for 3-point flexure test were fabricated by five processing methods such as self-curing, pressure pot, boiling water, processing, and light curing. Finally to evaluate the effect of surface designs for repaired resin, three surface designs(butt, bevel, inverse bevel) were tested. Within the limit of this study, following conclusions were drawn. 1. Lucitone denture base material showed highest flexural strength of $131.37{\pm}2.15MPa$, and there were significant differences in stength between Lucitone and other resins. 2. Between two different self curing methods, self curing repair resin, Lang, cured by pressure pot method showed highest flexural strength, $58.49{\pm}4.89MPa$. 3. Among the heat cured repair resins, maximum transverse strength value of $88.69{\pm}16.60MPa$ was recorded in Lucitone group cured by processing method. 4. Inverse bevel joint design showed significantly higher bond strength than butt joint group, Maximum bond strength was $59.36{\pm}1.33MPa$ in inverse bevel joint design group.

• 대한기계학회논문집A
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• 제28권5호
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• pp.489-494
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• 2004

Long Period Gratings (LPG) is currently receiving considerable attention because of their consistent measuring results fur pressure, temperature, strain and flow. LPG is easier to prepare and has a high sensitivity compared with Fiber Bragg Gratings (FBG). In addition, this kind of optical fiber sensors could be used for implementations in various structures. In this paper, LPG was used to monitor in situ the resin flow and the curing process in VARTM (Vacuum Assisted Resin Transfer. Molding). In order to demonstrate the effectiveness of the method, FBG is inserted into the glass mat to monitor the resin flow using optical spectrum analyzer (OSA). The curing reactions in VARTM are also observed using the same method. From the results, the attenuation wavelength shift and the loss change of attenuation band can be obtained from the status of the RTM (Resin Transfer Molding) sample owing to the internal variations of the .effective index, temperature, and pressure. It is shown that the proposed LPG is more effective in monitoring the curing reaction than FBG.

• 대한소아치과학회지
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• 제26권2호
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• pp.296-309
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• 1999

가철성 상교정 장치에 많이 사용되는 자가중합형 상교정용 레진의 미반응 단량체는 레진의 물성과 생물학적인 면에 많은 영향을 끼친다. 따라서 미반응 단량체를 최소화하고 중합률을 최대로 하는 중합방법에 대한 연구는 중요한 의의를 갖는다. 저자는 자가중합형 상교정용 레진의 중합시간과 중합방법에 따른 중합률을 비교해보기 위해 시편을 다음과 같이 5군으로 나누어 연구를 진행하였다. 상교정용 레진의 분말과 용액을 혼합하여 제 1군은 $28^{\circ}C$의 공기중에 보관하였고, 제 2군은 $28^{\circ}C$의 물에, 제 3군은 $28^{\circ}C$의 물과 30psi의 압력에, 제 4군은 $43^{\circ}C$의 물에, 제 5군은 $43^{\circ}C$의 물과 30psi의 압력하에 각각 보관하였고, 10분, 1시간, 12시간, 1일, 3일 경과 후에 각 시편을 Fourier 변환적외선분광법을 이용하여 중합률을 측정하여 다음과 같은 결론을 얻었다. 1. 모든 군에서 중합시간이 경과함에 따라 중합률도 지속적으로 증가하는 양상을 보였다. 10분 경과 후의 결과와 비교하여 볼 때, 제 1군은 12시간 경과 후부터 중합률의 증가가 유의성이 있었고, 제 2군과 3군, 4군, 5군은 1시간 경과 후부터 유의성이 있었다(p<0.05). 2. 10분과 1일, 3일 경과 후에 제 5군, 제 4군, 제 3군, 제 2군, 제 1군의 순서대로 중합률이 높았다. 3. 중합시 온도에 따른 비교에서, 1일 경과 후를 제외하고는 모든 시간에서 $43^{\circ}C$에서 중합시킨 군의 중합률이 $28^{\circ}C$에서 중합시킨 군의 중합률 보다 유의성 있게 높았다(p<0.05). 4. 압력은 12시간 경과 후를(p<0.05) 제외하고는 중합률에 영향을 주지 못했다. 5. 보관방법은 1시간 경과 후를(p<0.05) 제외하고는 중합률에 영향을 주지 못했다.

• 한국기계가공학회지
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• 제19권12호
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• pp.87-97
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• 2020

In this study, a UV-cured GFRP molding is made using a combination of hand lay-up and resin transfer molding, and its properties are analyzed. The molded plates produced using various vacuum pressures (0 mmHg, -450 mmHg, and -760 mmHg) are examined via a comparison of hand lay-up molding and resin transfer molding. Tests are conducted by processing tensile specimens (ASTM D-5083), flexural test specimens (ASTM D-790), and ILSS test specimens (ASTM D-2344) according to each ASTM standard with a molded plate. Similarly, the UV-cured GFRP molding is compared against GFRP using epoxy. It was confirmed that the mechanical strengths of all the specimens increased when the vacuum pressure was increased and when UV curing was applied. This is believed to be because as the vacuum pressure increases, the pores of the cured specimen are removed, thereby reducing defects, and the bonding force between the glass fiber and the resin is stronger than that of the epoxy resin. It is expected that if resin transfer molding methods and UV-cured resins are used for molding GFRP composites in industry, products with better mechanical properties and faster curing time will be produced.

• 농업과학연구
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• 제45권3호
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• pp.475-484
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• 2018

Nitrite is an essential additive for the manufacture of cured meat products. This study was conducted to investigate the curing effect of the plasma treated juice of red Perilla in meat batter. The nitrite content in the juice of red Perilla was increased by the indirect treatment of atmospheric pressure plasma, and the lyophilized powder of red Perilla juice contained 9,133 ppm of nitrite. A meat batter without a nitrite source was prepared as a negative control (NC), and the meat batters cured with sodium nitrite (PC), celery powder (CP), and the lyophilized powder of red Perilla juice treated with atmospheric pressure plasma (PTP) at 70 ppm level of nitrite were prepared. The PTP showed the highest pH and the lowest cooking loss among the treatments. There were no significant differences in the nitrosyl-hemochrome content in the cooked meat batters of the PC, CP and PTC. However, the PTP had a lower CIE $a^*$-value compared to the PC and CP. The malondialdehyde content in the cooked meat batters was significantly lower in the CP and PTP than in the NC while there was no significant difference between the NC and PC. Based on the results of this study, the plasma treated juice of red Perilla can be used as a new natural nitrite source for cured meat products.