• 한국전자통신학회논문지
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• 제17권2호
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• pp.255-264
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• 2022

종래의 spot형 UV경화기는 복수의 렌즈를 이용한 collimator 광학계를 구성하여 광속을 광케이블로 입사하도록 하고 있다. 전달 광 효율을 높이기 위해 3매 이상의 렌즈로 구성된 collimator 광학계가 필요하며 이에 따라 광학계 정렬에 어려움이 있고, 시스템을 컴팩트하게 구현하기 어렵다. 본 연구에서는 3매 렌즈로 구성된 collimator 광학계와 동등한 수준의 스폿 직경 및 광 효율을 구현할 수 있는 단일 TIR 렌즈 collimator 설계하였다. 이를 통해 최소 조도 편차를 갖는 경화 위치에서의 광 효율이 33.2 % 수준으로 참조 collimator 광학계의 성능과 유사한 수준을 확보하였고, 경화면에서의 조도 편차는 18.8 % 수준으로 양호한 성능을 확보하였다. 또한, 이미지 면에서의 조도 평탄화 기능을 갖는 fly-eye lens를 condensing 렌즈 앞단에 배치함으로써, TIR 렌즈만 적용한 경화 광학계와 비교할 때, 유효 경화영역 직경이 5.0 mm에서 3.0 mm 로 줄어 보다 높은 경화 에너지 밀도를 구현할 수 있었으며, 조도 편차는 14.4 % 수준으로 현격히 개선할 수 있음을 확인하였다.

• 한국건축시공학회지
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• 제16권6호
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• pp.529-534
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• 2016

칼슘실리케이트계 무기단열소재는 주원료로 시멘트를 90%를 사용하는 다공성 무기단열소재이다. 기존 무기단열소재와 달리 고온의 수화반응 처리가 없기 때문에 가격이 저렴하며, 불연소재의 원료를 사용하여 화제의 위험성도 적다. 칼슘실리케이트 단열소재는 $0.13g/cm^3$의 밀도와 0.050W/mK이하의 우수한 열전도도를 갖는 단열소재이다. 칼슘실리케이트 단열소재는 경량화 될수록 내부 기포를 다량 함유해야 하며 기포를 다량 함유함에 따라 단열성 또한 우수해진다. 본 연구에서는 다량의 기포를 함유하며 일정강도발현을 목표로, 칼슘실리케이트계 무기단열소재의 주성분인 시멘트가 수화반응에 따라 초기 및 장기강도발현하는 특성을 이용하여 칼슘실리케이트계 무기단열소재에 적용하여 물리적 특성을 알아보고자 하였다.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.15-20
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• 2016

좁은 면적을 단기간에 개량시킬 수 있는 장점이 있는 그라우팅 공법은 지반의 특성과 지하수위 등에 따라 주입 효과의 차이가 있다. 특히 투수성이 큰 지반에서는 시간 경과에 따라서 용탈현상이 발생하여 강도저하 및 차수 성능이 저하되어 품질에 문제가 생길 수 있다. 최근 이와 같은 문제점을 해결하기 위해 초기강도 확보 및 용탈 방지와 동시에 균열 자기치유 특성을 가지는 SSG가 개발되었다. 이 연구에서는 두 가지 양생조건에 대해 SSG의 일축압축강도 시험을 수행하여 양생기간에 따른 일축압축 강도를 파악하였다. 또한 SSG와 기존의 LW 및 SGR의 일축압축강도와 비교하였다. 연구 결과, SSG가 상온 양생 및 저온 양생 모두에서 강도가 크게 측정되었으며, 초기 강도도 상대적으로 매우 우수한 것으로 나타났다.

• 한국건축시공학회지
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• 제7권1호
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• pp.107-113
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• 2007

This study investigates the filed application in Daebul Free Trade Zone applying both a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double layer bubble sheet. Test results showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall. In addition, a structure applying the flowing concrete method partially presented the micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing concrete method was 28%, compared with that of conventional one. For the compressive strength of specimens, standard curing specimens indicated $3{\sim}33%$ higher value than that of specimens cured besides the field construction. The specimens containing SRS improved the strength of $2{\sim}6MPa$, which is $10{\sim}22%$ higher than that of conventional concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.13-16
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• 2006

This study investigates filed application in Daebul Free Trade Zone of a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double bubble sheets. Test showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall, and a structure applying only the flowing method partially presented micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing method was 28%, compared with 100% of conventional one. Standard curing specimens had about $3{\sim}6%$ higher compressive strength than that of specimens cured at adjacent field construction. In addition, using SRS improved about $5{\sim}7MPa$, than that of conventional concrete at 91 days elapse.

• 대한치과보철학회지
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• 제28권1호
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• pp.193-202
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• 1990

The purpose of this study was to compare the fithness, hardness and bending strength of the conventional reliners and visible light curing reliner. Nine regions were selected in the upper transverse section which were thought to be of interest from a clinical standpoint and the discrepancies between the dentures and the master cast in these regions were determined by the coordinated measuring machine(UMM-500, Zeiss, W. Germany). The results were as follows ; 1. The experimental denture bases showed the lowest fittness at the central portion of the posterior palatal border and the intimate contact in the buccal flanges regardless of relining materials and relining methods. 2. The fittness of relined denture base was the best in autopolymerizing group and in the order of long processing, short processing and visible light curing group. 3. The fittness after 24 hour-storage in water was improved in long processing and autopolymerizing groups, but there was no significant difference. 4. The hardness was the highest in long processing group and decreased in the order of short processing, visible light curing and autopolymerizing group. 5. The bending strength was the highest in long processing group and decreased short processing, visible light curing, and aotopolymerzing group in order.

• Elastomers and Composites
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• 제53권3호
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• pp.150-157
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• 2018

Fatigue properties of rubber are one of the most important characteristics in the rubber industry. In this study, the fatigue properties of MREs (magneto-rheological elastomers) based on NR (natural rubber), EPDM (ethylene-propylene diene monomer), and AEM (ethylene/acrylic elastomer) were investigated. For comparison, MREs with a Shore hardness of 60A were prepared. According to the relative results, the fatigue properties of EPDM MRE were the worst. Thus, we investigated methods to improve the fatigue properties of EPDM MRE by varying the carbon black content and curing systems of EPDM as the matrix of the MRE. Dynamic properties were measured using a fatigue tester and an RPA (rubber process analyzer), and the XPS (X-ray photoelectron spectroscopy) was used to analyze the curing system of the EPDM matrix. According to the results, the Payne effect increased and the fatigue resistance decreased as the carbon black content increased. In case of the curing system, the CV (conventional vulcanization) system was superior to the EV (efficient vulcanization) system in terms of the fatigue resistance. This was because the number of flexible bonds in the case of the CV system was higher than that in the case of the EV system. However, the EV system showed excellent mechanical properties because it had many monosulfidic bonds with strong binding energy.

• 한국염색가공학회지
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• 제17권6호
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• pp.27-35
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• 2005

Conventional pad- dry-cure(thermo-fixation) process usually produces functional performance on both sides of a fabric. UV curing technique was applied to impart water- and oil-repellent finish effective only on the face of a PET knitted fabric. The preferential one-side coating, by virtue of the limited penetration of UV light, was achieved by W curing after padding of a fluorocarbon agent without special coating or printing equipments. The difference in the functional property of face and back sides was examined by measuring water and oil repellency at each side of the treated fabric. The influence of pre/post-irradiation dose and agent concentration on the performance of the finished fabrics were investigated. While increase in both resin concentration and post-irradiation did not have significant effect on the finish, UV pre-irradiation of PET fabrics caused remarkable influence presumably due to appropriate surface modification of PET fabrics required for facile wetting of the resin. The dimensional stability and color change of the UV cured fabrics measured by FAST and reflectance spectrophotometry showed significantly decreased color difference and increased percent extension compared with the samples pre-irradiated without agent application.

• Composites Research
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• 제21권1호
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• pp.16-21
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• 2008

일반적인 아미드형 가교제(HD)를 함유한 에폭시 수지의 가교거동을 캐슈너트 외피유(CNSL) 및 CNSL-포름알데하이드 수지(CFR) 그리고 피마자유 존재 하에서 시차열량계(DSC)를 이용하여 조사하였다. 가교반응에 대한 활성화 에너지를 여러 가지 가열속도에서 비등온 DSC 열량그래프로부터 계산하였다. 피마자유 존재 하에서 에폭시 수지의 가교는 1단계 반응을 나타낸 반면 CNSL 및 CFR 존재 하에서는 2단계 가교거동을 나타내었다. 즉, 에폭시 수지/CNSL(혹은 CFR)/HD 블렌드의 경우 경쟁적인 가교반응이 나타났다. HD가 없는 에폭시 수지/CNSL(혹은 CFR) 블렌드의 경우 CFR 시스템이 CNSL보다 낮은 가교엔탈피 값을 나타내었고, CNSL 및 CFR 함량이 증가할수록 가교활성화 에너지는 증가하였다.

• Restorative Dentistry and Endodontics
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• 제27권5호
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• pp.488-492
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• 2002

The purpose of this study was to evaluate the effectiveness of plasma arc curing (PAC) unit for composite and compomer curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing unit, the polymerization shrinkage rates and amounts of three composites (Z100, Z250, Synergy Duo Shade) and one compomer, that had been light cured by PAC unit or QTH unit, was compared using a custome made linometer. The measurement of polymerization shrinkage was peformed after polymerization with either QTH unit or PAC unit. In case of curing with the PAC unit, the composite was light cured with Apollo 95E for 6s, the power density of which was recorded as 1350 mW/$\textrm{cm}^2$ by Coltolux Light Meter. For light curing with QTH unit, the composite was light cured for 30s with the XL2500, the power density of which was recorded as 800 mW/$\textrm{cm}^2$ by Coltolux Light Meter. The amount of linear polymerization shrinkage was recorded in the computer every 0.5s for 60s. Ten measurements were made for each material. The amount of linear polymerization shrinkage for each material in 10s and 60s which were cured with PAC or QTH unit were compared with t test. The amount of polymerization shrinkage in the tested materials were compared with 1way ANOVA with Duncan's multiple range test. As for the amounts of polymerization shrinkage in 60s, there was no difference between PAC unit and QTH unit in Z250 and Synergy Duo Shade. In Z100 and Dyract AP, it was lower when it was cured with PAC unit than when it was cured with QTH unit (p<0.05). As for the amounts of polymerization shrinkage in 10s, there was no difference between PAC unit and QTH unit in Z100 and Dyract AP. The amounts of polymerization shrinkage was significantly higher when it was cured with PAC unit in Z250 and Synergy Duo Shade (p<0.05). The amounts of polymerization shrinkage in the tested materials when they were cured with QTH unit were Z250 (6.6um) < Z100 (9.3um), Dyract AP (9.7um) < Synergy Duo Shade (11.2um) (p<0.05). The amount of polymerization shrinkage when the materials were cured with PAC unit were Dyract AP (5.6um) < Z100 (8.1um), Z250(7.0um) < Synergy Duo Shade (11.2um) (p<0.05).