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방사성페기물 핵종분석 결과를 사용한 폐수지의 운반물등급 분류 방법
김태욱,최기섭,강기두,하종현,Kim, Tae-Wook,Choi, Ki-Seop,Kang, Ki-Doo,Ha, Jong-Hyun 한국방사성폐기물학회 2008 방사성폐기물학회지 Vol.6 No.1
In order to transport spent resin in a high integrated container made of high density polyethylene, a method for determining transportation grade by radioactivity analysis was developed. Ratios of radioisotopes in spent resin were derived from radioactivity analysis on spent resin. Associated curie-to-dose factors were determined to estimate radioisotope inventory from surface dose rates of spent resin. From the results, Activity limit of type A package was derived to be 1.19 TBq for HIC, and the corresponding surface dose rate was found to be 124.2 mSv/h.
빠르고 안정된 소결 특성을 갖는 Core-Shell 구조로 이루어진 레이저 소결용 메탈 복합 분말의 개발
방영길(Young-Kil Bang),최기섭(Ki-Seop Choi),박창현(Chang Hyun Park),김형일(Hyung-Il Kim),임병석(Byung-Seok Lim),김동수(Dong-Soo Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
In this work, metal powder which has core-shell structure was developed for the laser sintering process. The metal core of powder was coated by the polymer resin that can be melted by laser. To improve powder fluidity and adhesion force of powders, various additives(antioxidant, anti-additive, nano-material etc.) was added to the powder. In addition, it has good physical/chemical stability in comparison with commericialized powder.
SLS 공정을 이용한 산업용 SFF 시스템용 신소재 고분자분말 개발
방영길(Young-Kil Bang),최기섭(Ki-Seop Choi),박창현(Chang Hyun Park),김형일(Hyung-Il Kim),임병석(Byung-Seok Lim),김동수(Dong-Soo Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Polymers for laser sintering were needed in order to fabricate the articles with the three-dimensional duplication equipment of SLS (selective laser sintering) process. The thermal properties, particle size, distribution, and shape of polymer powder had a close relation with the processibility of laser sintering. In this study, we prepared new polymer powders with uniform size and higher bulk density by wet process. Wet process consists of several finely-controlled steps such as dissolution, nucleation, propagation and crystallization. Several additives were added to improve the thermal, rheological, and flow properties.
산소 플라즈마 처리된 그래핀 산화물이 PMMA/수산화알루미늄 컴포지트의 기계적 물성에 미치는 영향
김형일(Hyung Il Kim),김효철(Hyo Chul Kim),전소녀(Son Yeo Jeon),최호석(Ho Suk Choi),홍민혁(Min Hyuk Hong),최기섭(Ki Seop Choi) 한국고분자학회 2011 폴리머 Vol.35 No.6
Poly(methyl methacrylate)/aluminum hydroxide(PMMA/AH) 컴포지트의 기계적 강도를 향상시키기 위해 그래핀 산화물(GO)을 충전제로 사용하여 나노컴포지트를 제조하였다. GO는 흑연을 Hummers법으로 산화한 후 열 처리에 의해 박리시켜 제조하였다. PMMA/AH 컴포지트 매트릭스와의 계면혼화성을 향상시키기 위해 산소 플라즈마를 사용하여 노출 시간을 0분에서 70분까지 변화를 주어가며 GO 표면을 개질시켰다. 노출 시간이 50분까지 증가함에 따라 산소 플라즈마 처리한 GO를 충전제로 사용한 나노컴포지트는 PMMA/AH 컴포지트에 비해 굴곡강도, 굴곡탄성률, Rockwell 경도, Barcol 경도, Izod 충격강도 모두 현저히 증가하였다. 적절한 조건에서 산소 플라즈마 처리된 GO는 PMMA/AH 컴포지트 매트릭스와의 계면접착력이 매우 우수함을 파단면 모폴로지로부터 확인하였다. 하지만 GO의 함량 이 0.07 phr 이상으로 증가하면 충전제의 분산이 균일하지 못하여 나노컴포지트의 기계적 강도는 오히려 감소하는 경향 을 나타내었다. The nanocomposites containing graphene oxide (GO) were prepared in order to improve the mechanical properties of poly(methyl methacrylate)/aluminum hydroxide (PMMA/AH) composites. GO was prepared from graphite by oxidation of Hummers method followed by exfoliation with thermal treatment. The surface of GO was modified by oxygen plasma in various exposure times from 0 to 70 min to improve interfacial compatibility. Compared with PMMA/AH composites, the nanocomposites containing GO modified with oxygen plasma for the exposure time up to 50 min showed significant increases in flexural strength, flexural modulus, Rockwell hardness, Barcol hardness, and Izod impact strength. The morphology of fracture surface showed an improved interfacial adhesion between PMMA/AH composites and GO, which was properly treated with oxygen plasma. The mechanical properties of nanocomposites were deteriorated by increasing the content of GO above 0.07 phr due to the nonuniform dispersion of GO.
함산소불소화 처리된 그래핀 산화물 플레이크가 PMMA 인조대리석의 기계적 물성에 미치는 영향
김형일(Hyung Il Kim),김효철(Hyo Chul Kim),전소녀(So Nyeo Jeon),이영석(Young Seok Lee),홍민혁(Min Hyuk Hong),최기섭(Ki Seop Choi) 한국고분자학회 2012 폴리머 Vol.36 No.3
폴리(메틸메타크릴레이트)(PMMA) 매트릭스를 갖는 인조대리석의 기계적 강도를 향상시키기 위해 그래 핀 산화물 플레이크(GOF)를 충전제로 사용하여 나노컴포지트를 제조하였다. 충전제로 사용한 GOF는 흑연을 Hummers법으로 산화한 후 열처리에 의해 박리시켜 제조하였다. PMMA 매트릭스와의 계면혼화성을 향상시키 기위하여 다양한 산소: 불소 조성의 함산소불소화 처리로 GOF 계면을 개질시켰다. 산소함량 50% 이상에서 함 산소불소화 처리한 GOF를 충전제로 사용한 나노컴포지트는 기존 인조대리석에 비해 굴곡강도, 굴곡탄성률, Rockwell경도, Barcol경도, Izod충격강도 모두 현저히 증가하였다. 적절히 함산소불소화 처리된 GOF는 PMMA 매트릭스와의 계면접착력이 우수함을 파단면의 모폴로지로부터 확인하였다. 하지만 GOF 충전제의 함량이 0.07 phr 이상으로 증가하면 충전제의 분산이 균일하지 못하여 인조대리석의 기계적 강도는 오히려 감소하는 경향을 나타내었다. The nanocomposites containing graphene oxide flakes were prepared in order to improve the mechanical properties of artificial marbles based on poly(methyl methacrylate)(PMMA) matrix. Graphene oxide flakes were prepared from graphite by oxidation with Hummers method followed by exfoliation with thermal treatment. Surface of graphene oxide flakes were modified with oxyfluorination in various oxygene: fluorine compositions to improve the interfacial compatibility. The nanocomposites containing graphenes modified with oxyfluorination in the oxygen content of 50% and higher showed the significant increase in flexural strength, flexural modulus, Rockwell hardness, Barcol hardness, and Izod impact strength. The morphology of fractured surface showed the improved interfacial adhesion between PMMA matrix and the graphenes which were properly treated with oxyfluorination. The mechanical properties of nanocomposite were deteriorated by increasing the content of graphene above 0.07 phr due to the nonuniform dispersion of graphenes.