에폭시 배합비에 따른 내열성 복합재료 최적조건

신평수 ( Pyeong Su Shin ),왕작가 ( Zuo Jia Wang ),권동준 ( Dong Jun Kwon ),최진영 ( Jin Yeong Choi ),성일 ( Ill Sung ),진달샘 ( Dal Saem Jin ),강석원 ( Suk Won Kang ),김정철 ( Jeong Cheol Kim ),박종만 ( Joung Man Park ) 한국복합재료학회 2014 Composites research Vol.27 No.4

2개 이상의 에폭시 기지재의 배합비를 이용하여 최적의 에폭시 복합재료를 제조하였다. 이 실험에서 노볼락계 에폭시 및 아이소시아네이트계 에폭시를 기지재로 사용하였다. 그에 따라 화학적 조성의 변화를 이용하여 다양한 실험을 통한 최적의 에폭시 배합비를 유추하였고, 에폭시의 내열성 및 계면을 파악하기 위하여 열중량측 정기를 이용하여 유리전이온도의 변화를 파악하였고 정적 접촉각을 측정하였다. 기계적 물성을 파악하기 위하여 에폭시 배합비에 따른 유리섬유/에폭시 복합재료의 인장, 압축, 굴곡강도를 상온에서 및 노화시간에 따라 파악하였다. 에폭시와 유리섬유간 계면을 개념도로 나타냈다. 시험 결과 에폭시 배합비에 따른 적외선 피크 및 유리전 이온도 변화를 확인하였다. 서로 다른 에폭시의 배합비가 1:1일 때 기계적물성이 상대적으로 좋은 것을 확인하였다. Composites Research : The optimum condition of glass fiber/epoxy composites was investigated according to mixing ratio of two epoxy matrices. Novolac type epoxy and isocyanate modified epoxy were used as composites matrix. Based on chemical composition of mixing matrix, optimum mixing ratio of epoxy resins was obtained through various experiments. In order to investigate thermal stability and interface of epoxy resin, glass transition temperature was observed by DSC instrument, and static contact angle was measured by reflecting microscope. Change of IR peak and Tg was conformed according to different epoxy mixing ratio. After fabrication of glass fiber/epoxy composites, tensile, compression, and flexural properties were tested by UTM by room and high temperature. The composites exhibited best mechanical properties when epoxy mixing ratio was 1:1.

고온노출된 강섬유보강 콘크리트의 인장성능에 대한 실험적 연구

문도영,Moon. Do Young 한국방재학회 2013 한국방재학회논문집 Vol.13 No.1

본 논문에서는 고온 노출된 강섬유 보강콘크리트의 인장성능을 실험적 연구를 통하여 검증하고자 하였다. 실험방법은 낮은 변동성을 특징으로 하는 DPT를 이용하였다. 일반적인 후크강섬유와 트위스트 강섬유, 0.25~1.0%의 강섬유 혼입률, 섬유형상비를 변수로 하여 실험을 수행하였다. 시험체는 고온 전기로에서 <TEX>$300^{\circ}C$</TEX>, <TEX>$500^{\circ}C$</TEX> 및 <TEX>$700^{\circ}C$</TEX>의 온도에서 2시간 노출되었으며, 12시간 동안 자연냉각 된 후에 가력되었다. 실험결과, 섬유혼입률이 증가할수록, 형상비가 클수록, DPT 인장강도가 증가하는 것으로 나타났다. 섬유종류의 영향은 다른 변수에 비하여 그 영향이 미미한 것으로 판단되었다. 실험결과를 근거로 강섬유의 혼입량과 형상비의 영향을 고려할 수 있는 노출온도 수준에 따른 DPT 인장강도 예측식을 제시하였다. Tensile strength of steel fiber-reinforced concrete was investigated with experimental program. For the investigation, Double Punch Test, which is known as a test method with low validity, was used. Fiber type(hooked and twisted fiber), mix ratios by volume ranged from 0.25% to 1.0%, aspect ratio were used as variables for the tests. The specimens were exposed to the elevated temperatures(<TEX>$300^{\circ}C$</TEX>, <TEX>$500^{\circ}C$</TEX> and <TEX>$700^{\circ}C$</TEX>) for 2 hours and placed at ambient temperatures for 12 hours before testing. Results demonstrated that residual tensile strength increases as mix ratio and aspect ratio increase. The effect of fiber type was insignificant. Based on the test results, the linear equation for prediction of DPT residual tensile strength was proposed in terms of mix ratio and aspect ratio.

일체형 완속교반/침전 그물망 압착식 섬유여과장치를 이용한 하수처리장 반류수 내 고농도 인 및 부유물질 처리

김정숙 ( Jeongsook Kim ),김민호 ( Min-ho Kim ),김미란 ( Mi-ran Kim ),장정국 ( Jeong-gook Jang ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.6

An integrated slow mixing/sedimentation and net fit fiber filtration system has been developed to reduce the high concentrations of suspended solid (SS) and total phosphorus (T-P) in the reject water from sewage/wastewater. A filtration device used in this experiment consists of coagulation, in-line mixing, air injection, slow mixing/sedimen-tation, and filtration processes. The performance test using this device was carried out with six operational modes for reject water from sewage treatment plant. Experimental conditions used were 16.7, 33.3, 41.7 and 50.0 ton/day of flow rate and 2~4 of Al/P molar ratio. By injection of coagulant in each operational mode, the high removal efficiencies of SS and T-P were obtained, but continuous operation time was decreased to 7.8~11.4 min in most modes. However, when the Mode 5 of the developed filtration device was applied, the continuous operation time was maintained up to 88.2 min. Also, it was found that the continuous operation time in the Mode 5 using the developed system was increased from 8 to 11.3 times longer than those in other modes. Backwashing flow rate was also very low at 5.4% of total filtered water. Therefore, it can be concluded that the Mode 5 of the developed filtration system was the most efficient treatment method for the removal of high concentrations of SS and T-P.

Ternary mixed-gas separation for flue gas CO₂ capture using high performance thermally rearranged (TR) hollow fiber membranes

Woo, K.T.,Dong, G.,Lee, J.,Kim, J.S.,Do, Y.S.,Lee, W.H.,Lee, H.S.,Lee, Y.M. Elsevier Scientific Pub. Co 2016 Journal of membrane science Vol.510 No.-

A comprehensive study evaluated the mixed-gas (CO<SUB>2</SUB>/N<SUB>2</SUB>/O<SUB>2</SUB>) separation performance of thermally rearranged polybenzoxazole-co-imide (TR-PBOI-AD5) hollow fiber membranes fabricated in-house (pure-gas CO<SUB>2</SUB> permeance of 481GPU and ideal CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity of 17.7). The criteria for the determining the two major operating conditions (pressure ratio and feed flow rate) were identified in order to deliver optimal separation performance with low process energy consumption. By varying the feed CO<SUB>2</SUB> concentrations, it was found that a single-stage operation using TR-PBOI-AD5 (produced by bis-APAF and DAM as the TR-able and non-TR-able diamines, respectively, based on 6FDA) hollow fiber membranes was not sufficient to meet the required 90% permeate CO<SUB>2</SUB> purity target, while a two-stage operation using the same membranes led to a permeate CO<SUB>2</SUB> purity (81%) closer to the target value. The comparison study among the TR polymer membranes and three other polymer membranes highlighted the significance of an appropriate choice of a mixed-gas separation operating scheme to fully utilize the exceptional permeation properties of the recently developed high performance membranes such as TR polymeric membranes.

목재섬유와 면섬유의 혼합에 따른 수초지의 파괴인성 변화

김정중,박종문,장동욱,윤상구,신현식 한국펄프·종이공학회 2014 펄프.종이技術 Vol.37 No.5

Conditions of paper manufacturing process should be changed depending on the end use and paperproperties. Most of the case, mixed pulps with long softwood fibers and short hardwood fibers are usedto achieve proper qualities of product with reasonable production cost. For specialty paper manufacturethe wood pulp and cotton linter pulp are usually mixed together. The objectives of this study is to analyzephysical, mechanical and fracture mechanical properties of paper depending on SwBKP, HwBKP andcotton linter pulp(CLP) mixing. When the mixing ratio of SwBKP was increased, strength properties,such as tensile, tear, and folding endurance, were also increased. When the mixing ratio of SwBKP andHwBKP was increased, stress concentration index was decreased and fracture toughness was increased.

위조문서 감별을 위한 현대 문서용지 특성 분석 ( II )

최경화(Kyoung-Hwa Choi),이재훈(Jae-Hoon Lee),류정용(Jeong-Yong Ryu) 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.4

In order to investigate the characteristics of modern paper, the fiber type and blending ratio of the domestic paper document samples for which the year of publication has been confirmed were examined. In the results, major fibers including softwood bleached kraft pulp (SwBKP), hardwood bleached kraft pulp (HwBKP) and bleached mechanical pulp (MP) were found to be used in modern paper. SwBKP has been steadily used up to 23% of the total fiber in modern paper to improve paper strength. Prior to 1980, MP was used as the main fiber furnish of the document paper. However, since 1980, it has changed from MP to HwBKP. This change is presumably due to the high lignin content of the mechanical pulp that causes fast color reversion. It also appears to be affected by increasing consumer demand for high quality such as high brightness and excellent printing property. However, some samples produced after 1980 still contain small amounts of MP fibers. Since most of the pulp used in Korean paper mills is imported pulp, a small amount of MP is sometimes used to reduce production costs. To increase the reliability of this study, we need to increase and to update data base continuously.

섬유혼입비 및 ERCO 혼입율 변화에 따른 HPFRCC의 공학적 특성

조성준(Jo, Sung-Jun),한천구(Han, Cheon-Goo) 대한건축학회 2017 大韓建築學會論文集 : 構造系 Vol.33 No.2

Recently, because of increasing terrorisms, and accidents related with explosion, concerns on safety of human in building structures have been increased globally. Keeping up with this global issue, the research on high performance fiber reinforced cementitious composites (HPFRCC) with improved toughness due to the fiber reinforcement has been conducted in order to compensate the drawbacks of currently used concrete materials with low tensile strength and brittle failure mode. From the former research, some problems of severe autogenous shrinkage due to low water-to-binder ratio came up, and to achieve the efficient anti-explosive performance the optimizing proportion between short steel (SS) fiber and long organic (OL) fiber for combined fiber-reinforcement were required. Therefore, in this research, before applying HPFRCC on test-bed in military facility, the influence of various proportions of SS and OL and ERCO dosages on engineering properties of HPFRCC was analyzed. From the experiment, considering appropriate workability, strength, and autogenous shrinkage reducing, 1 to 1.5 of SS to OL and 0.5 % of ERCO addition were evaluated as the most appropriate conditions.

탄소 섬유강화 복합소재의 고압 수지이송 성형공정에서 직선형 믹싱헤드의 성능 및 유용성 평가

한범정(Beom Jeong Han),정용채(Yong Chai Jeong),황기하(Ki Ha Hwang),강명창(Myung Chang Kang) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.5

The high-pressure resin transfer molding (HP-RTM) technology has been commercialized for fast production of fiber reinforced composite materials. The high-pressure mixing head was one of the most core component of the HP-RTM process. In this study, a mixing head was systematically designed, manufactured and evaluated. This mixing head was composed of a nozzle, a mixing chamber, a cleaning piston part, and an internal mold release part. In actual, a straight-type structure was newly designed instead of the conventional L-type structure for improving the maximum mixing pressure and mixing ratio precision. The performance of mixing head was showed maximum mixing pressure of 15.22MPa and mixing ratio precision of 0.12%. CFRP molding experiments were successfully obtained a 6~11 laminating carbon sheet using HP-RTM presses and specimen molds.

섬유 혼합토의 공학적 특성

장병욱 ( Chang Pyoung Wuck ),박영곤 ( Park Young Kon ),이상호 ( Lee Sang Ho ),송창섭 ( Song Chang Seob ) 한국농공학회 2002 韓國農工學會誌 : 전원과 자원 Vol.44 No.1

Natural resources fur the construction materials such as good soil, sand, and coarse aggregates have been encountered to be short due to excessive use by human. Even though some soil has been found to be unsuitable for construction materials, soil with reinforcement can naturally be an answer to these alternatives. According to recently published papers on fiber mixed soil, fiber mixed with soil can improve shear strength, compressive strength and post-peak load strength retention. In this study, a series of tests were performed to clarify the characteristics of fiber mixed soil and to give basic data for design and construction and their engineering properties, that is, unconfined compressive strength, splitting tensile strength, shear strength, crack by drying, freeze-thaw, creep and Poisson`s ratio, were investigated and analyzed. It has been shown that fiber mixed soil is one of good alternatives fur the civil and building construction materials.

강섬유 보강 콘크리트의 표면전기저항 민감도

문도영 한국방재학회 2012 한국방재학회논문집 Vol.12 No.5

콘크리트 구조물의 상태평가에서, 부식율 또는 투과성능은 중요한 체크항목중의 하나이며, 일반적으로 표면전기저항 측정치를이용한 방법을 통해 평가된다. 그러나, 이와 같은 평가방법은 내부 이형철근 등과 같은 전도물질에 의하여 영향을 받는 것으로알려져 있다. 이러한 전도물질의 간섭현상은 강섬유보강콘크리트의 경우에 더욱 심화될 수 있다. 본 연구에서는 콘크리트에 분포된 강섬유가 표면전기저항에 미치는 영향에 대한 정보를 제공하기 위하여 강섬유를 1%, 2% 및 3% 포함하고 있는 시편에대한 실험을 수행하였다. 또한, 함수량, 이형철근 및 철근의 부식상태에 따른 영향을 조사하였다. 실험결과에 따르면, 강섬유의혼입량과 함수량의 영향이 다른 인자들에 비하여 큰 것으로 나타났다. 따라서, 강섬유 보강콘크리트의 부식율 또는 투과성능을평가하기 위해서는 함수량과 강섬유의 혼입량에 대한 세심한 고려가 필요하다. For condition surveying of concrete structures, corrosion rate or permeability is to be one of important checklists and is usually evaluated by resistivity measurement on concrete surface. But, it is known that the conductive materials, such as embedded steel rebars, affect the observed resistivity. This could be more severe in the case of steel-fiber reinforced concrete structures. In this study, the experimental program were conducted on steel-fiber reinforced concrete specimens with 1%, 2% and 3 Vol% of hooked steel fibers to provide more information about the effect of distributed steel fibers on electrical resistivity measurements on concrete structures. The effect of moisture content, embedded steel reinforcement and its corrosion state were investigated also. The results show that the amounts of mixed fibers and moisture content significantly affect more than others. Consequently, their effect should be carefully considered for the evaluation of corrosion rate or permeability of steel-fiber reinforced concrete structures.