• Resources Recycling
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• v.25 no.2
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• pp.60-68
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• 2016

In this study, earlier analyzed tetrapod, one of an original group of offshore constructions studied for manufacturability of the concrete using the properties of steel making slag aggregate. steel making slag aggregate assessment, RCS and Blast Furnace Slag : the 20 mm air-cooled slag and combinations by 50 %, aggregate properties on the most appropriate for the properties of recycled aggregate concrete optimal mix, and assessing it. Properties of concrete used to be derived are judged as to bury the studies show that the hollowing-out of the RCS, plastic sole use is in the workability of the aggregate, plastic in the 20 mm slag also assessed to be a slight disadvantage, but RCS by mixing air-cooled coarse and 50 percent to 20 percent 50 mm. Thus, steel making slag marine structures using recycled aggregate, in rapid chilled slag or air-cooled slag. The sole use of the aggregate them than to combine the aggregate of concrete. After they satisfy the quality standard quality shall be used will aggregate steel making slag who meet the criteria concrete manufacturing in general or par with the aggregate of concrete. Performance was assessed as to develop a more than that.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1677-1685
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• 2014

Short discrete fibers compounded with concrete can enhance the tensile resistance and ductility of concrete. Recently, the effectiveness of the reinforcement has increased according to the increasing length of steel fiber. However, the lengthening of steel fiber requires reducing the ratio of the fiber content to remain the workability and quality of concrete. Thus, the present study evaluated the flexural performance of fiber reinforced concrete with less than l.0% fiber volume ratios of steel fiber, 30mm and 60mm long, and polypropylene fiber, being evaluated as a good reinforcing material with chemical stability, long-term durability, and cost effectiveness. Concrete with more than 0.25% steel and 0.5% polypropylene fibers improved the brittle failure of concrete after reaching cracking strength. Concrete reinforced with polypropylene exhibited deflection-softening behavior, but that with more than 0.5% polypropylene delayed stress reduction and recovered flexural strength by 60 to 80% after cracking strength. In conclusion, concrete reinforced with more than 0.75% polypropylene could improve structural flexural performance. In particular, energy absorption capacity of reinforced concrete with 1.0% polypropylene fiber was similar to that with 0.5% and 0.7% steel fibers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.73-82
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• 2017

In Korea, previous certification of water supply infrastructure was mainly focused on economical and physical aspects. Recently, hygienic safety of water supply service has become a sensitive and important issue to our people for evaluating the water quality with growth of economy and education system. According on water quality in 497 Korean water supply facilities, pH values in the supplied water have ranged between 5.8-8.5. However, little is known about metal leachability at the pH conditions observed in the real water supply systems because a fixed pH condition (pH 7.0) has been used in the current standard method, 'Hygienic Safety Testing Method', in water supply. In this work, we examined the effects on heavy metal leachability with pH differences in the water supply pipes which are typically used in Korea. As a result, the amounts of metal leachability were tended to increase when pH levels were decreased. Especially at pH 5.8, Cu leachability from Cu pipes was found to exceed the public health standard level even after applying a normalization factor (NF) given by the current Korea standard method. The Cr and Cu leached from stainless steel pipes, Cd, Pb, Cu, and Zn from Cu-based pipe fittings, and Zn from Zn-based pipe fittings were exceeded the Korean hygienic safety standards while, after applying the NF, concentrations of the leached metals were satisfied with the current Korean standard. The findings from this work provide implications on the needs of reforming the current hygienic safety standard methodology.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.345-356
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• 1994

Each of the three cationized compounds synthesized previously, poly(OMA-co-DAMA)[PODC], poly(DMA-co-DAMA)[PDDC] and poly(EMA-co-DAMA)[PEDC] was blended with waxes, emulsifiers and cationized fatty carbamide(ODTCC) synthesized in this study for the preparation of some durable softening water-repellenting agents, PODCW, PDDCW and PEDCW. The results of washability, tearing strength, crease recovery and contact angle of the cotton fabrics treated with PODCW, PDDCW and PEDCW with and without textile finishing resin, showed remarkable improvement of the physical properties. Rating of water repellency of cotton fabric treated with PODCW was 80, but those treated with PDDCW and PEDCW were not high enough to use in industry. Proper curing temperature of the synthesized water-repelleting agents was $140^{\circ}C$; proper using concentration was 3wt%; sodium acetate was the best catalyst for water-repellenting agents among the used, and proper concentration was 0.6wt%. From the results of reaction mechanism of cellulosic fiber with water-repellenting agent and washability of the fibers treated with water-repellenting agents the prepared water-repellenting agent proved to be durable. Surface structures of cotton fabrics treated with water-repellenting agent were investigated by SEM.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1253-1254
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• 2007

본 논문에서는 에너지 수요의 급증으로 세계적으로 에너지 수습의 불안이 고조되고 있는 이시점에서 차세대 친환경 에너지원으로 각광 받고 있는 연로전지에 대한 모니터링 사업에 대한 실증화 연구에 관하여 논의 하고자 한다. 한국 가스공사에서 주관한 1kw가정용 연료전지 시스템 모니터링사업은 3차년도 사업으로 나뉘어져있으며 본연구는 1차연도 사업으로 3000시간동안의 시스템의 평가 설치 운전을 하고 가정용연료전지대규모 모니터링을 통한 실측 데잉터를 분석하고 Cost down 과 시스템의 내구성향상, 부품국산화율 향상및 과제 도출을 통한 가정용 연료전지 보급기반을 목적으로 하고 있다.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.129-135
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• 2018

In the stretchable electronic devices, the stretchable substrate is a very essential material which determines the stretchability, performances and durability of the stretchable electronic devices. In particular, the current stretchable materials have hysteresis making difficult to used as sensors and other electronic devices. In this study, we developed a PDMS-Ecoflex hybrid stretchable substrate mixed with PDMS and Ecoflex material in order to increase stretchability and improve hysteresis characteristics. Mechanical behavior of the hybrid substrate was evaluated using a tensile test, and optical transmittance of the hybrid substrate was also measured. As the content of Ecoflex increases, the PDMS-Ecoflex hybrid substrate becomes more flexible, and the elastic modulus decreases. In addition, the PDMS substrate failed a tensile strain of 270%, while the PDMS-Ecoflex hybrid substrate did not fail even at 500% strain indicating excellent stretchability. In the repeated tensile test, the hybrid substrate with 2:1 mixing ratio of PDMS and Ecoflex showed hysteresis. On the other hand, in the case of the hybrid substrate with the mixing ratio of 1:1, hysteresis did not occur at a strain of 50% and 100%. Hence, we developed a stretchable substrate with over 150% stretchability and no hysteresis characteristics. The optical transmittance of the Ecoflex substrate was 68.6%, whereas the transmittances of the hybrid substrate with mixing ratio of 2:1 and 1:1 were 78.6% and 75.4%, respectively. These results indicate that the PDMS-Ecoflex hybrid substrate is a potential candidate for a transparent stretchable substrate.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.139-144
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• 1995

It is the aim of this study to introduce the performance and application of new repair system for the exterior wall by durability failure caused seasand especially. The elementary performance of this repair system is as follows (1)All the layer in the repair are cement based, same with the mother conrete (2)this repair system use SBR admixture (3)This cement and mortar powder for this repair system are premixed and ready to use just adding admixture at the job site.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.73-77
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• 1992

환봉소재의 정밀절단을 위한 고속 환봉절단 공정에 있어서 절단금형은 공정중 막대한 타격력을 받기 때문에 금형의 파손방지 및 내구성향상을 위한 금형설계 기술이 절실히 요구되고 있다. 이같은 절단금형의 최적설계를 위해선 타격시 램이 금형에 가하는 충격력에 대한 예측이 필수적이므로 본 연구에서는 환봉절단 공정에 대한 동역학적 해석을 통해 충격력과 접촉시간을 이론적으로 구하였으며 이를 기존의 이론값과 비교한 결과, 보다 정확한 충격력의 예측이 가능하였다. 그리고 본 이론을 국내 최초로 개발된 환봉절단 장치에 적용하여 타격속도, 절단저항, 램과 금형의 하중비 등의 인자들과 충격력 사이의 관계를 밝혀냄으로써, 향후 최적금형 설계를 위한 데이터 베이스를 구축하였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.146-149
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• 1995

석탄 가스화 복합발전 시스템(IGCC)에서 집진은 가스 터빈의 입자에 의한 마모와 침식으로부터의 보호와 분진 배출의 환경 규제를 만족하기 위한 필수 공정이다. 특히 고온고압에서 집진이 수행되면 시스템의 열효율 향상은 물론 가스정제 시스템을 간단히 함으로써 건설비와 운전비의 절감에도 큰 효과를 거둘 수 있다. 석탄 가스화 공정에서 평균 입경이 2 - 3$\mu\textrm{m}$의 입자가 10g/m이상으로 발생되는 농도를 10mg/m이하로 처리하기 위하여 많은 집진 시스템이 제안되고 있지만 IGCC에 도입하기 위한 집진시스템으로서 세라믹 캔들 필터가 제일 타당하다. 세라믹 캔들 필터로 절데 집진 일경이 5$\mu\textrm{m}$이하이고 전체 집진 효율을 99.6% 이상 수행할 수 있다. 세라믹 필터를 이용한 상용화 개발 현황은 현재 세계적으로 bench급, pilot급, 그리고 상용화급 IGCC공정에 도입되어 그 성능이 검정되고 있으며 본 시스템의 내구성과 안정성이 상용화에 충족한 것으로 판명되고 있다. 본 연구에서는 고온고압용 세라믹 필터 집진시스템을 개발하기 위하여 제작된 bench급 집진 공정 및 세라믹 필터설계의 기술적 문제점을 소개하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.297.1-297.1
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• 2013

PV모듈은 다수의 태양전지를 상호 연결한 후 라미네이션(Lamination)공정을 통해 오랜 시간 견딜 수 있는 하나의 구조물로 만든 것이다. 외부환경 노출되어 장시간 발전하는 PV모듈은 설하중 풍하중 등 다양한 응력을 받는다. 이러한 외부 응력은 PV모듈 내부의 태양전지를 파손시켜 발전 출력의 감소를 발생 시킬 수 있다. 따라서 기계적 신뢰성을 보장하는 것은 매우 중요하며, PV모듈의 기계적 강도를 향상시키기 위한 연구가 활발히 진행되어지고 있다. 따라서, 본 논문에서는 PV모듈의 기계적, 물리적 변형을 최소화 하고자 PV모듈 전면에 사용되는 강화유리의 두께를 증가시켜 기계하중 시험을 진행하였다. 실험은 K SC IEC 61215의 PV모듈 인증시험 기준에서 제시하는 기계강도 시험과 동일한 방식으로 시험을 실시 하였으며, 전면유리 두께가 3.2 mm, 4 mm, 5 mm인 PV모듈을 사용하여 하중에 대한 최대변형과 출력 변화를 관찰하였으며, EL (electroluminescence) 측정을 통하여 기계강도 실험전 후의 모듈 내부 태양전지 파손 여부를 확인하였다. 이러한 결과는 PV모듈에 대한 내풍압 및 적설하중 등 Field에서 발생될 수 있는 물리적 내구성능을 분석하는데 많은 도움이 될 수 있다.