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Adhesion Behavior of Electroplated ABS
Jae Sik Seo(서재식) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Electroplating of metals on polymer materials is one of the best decorative processes for achieving low cost and light weight. However, low interfacial adhesion often limits practical utilization due to the potential peel-off behavior of metal layers. The interface between the metal layers and acrylonitrile-butadiene-styrene (ABS) substrate and its peeling mechanism are investigated as a function of etching time. Sa, the arithmetic average roughness of the unit area, and Sdr, the interfacial area ratio, are adopted instead of linear roughness, Ra, to quantify the surface profile. As the etching time increases, both Sa and Sdr for the etched ABS and corresponding metal side increase. The failure mode changes from adhesive to cohesive as the etching time increases, and the peel-off strength of the electroplated ABS exhibits a dependence on the tensile strength of the substrate. The peel-off strength of the electroplated ABS specimens increases to 8.46 N/cm after 30 min of etching time, but the interface degrades, forming inner voids. The Sdr ratio (Sdr, polymer/Sdr, plating) is proposed as a surface parameter to predict the peel-off strength of electroplated ABS and represents a new attempt to quantitatively correlate the interfacial morphology with the adhesion strength.
인터넷 및 스마트폰의 미디어 기능과 청소년 우울과의 관련성
홍연재 ( Yeon Jae Hong ),류승아 ( Seung Ah Rhew ),서재식 ( Jae Sik Seo ),김윤지 ( Yoon-ji Kim ),강동묵 ( Dongmug Kang ),김영기 ( Young-ki Kim ),김지훈 ( Ji-hoon Kim ) 대한의료커뮤니케이션학회 2017 의료커뮤니케이션 Vol.12 No.1
Purpose: As the internet use of teenagers become more common, the need for research on the relationship between the internet and youth depression has emerged. The purpose of this study is to investigate the relationship between internet use and adolescent depression. Methods: The subjects of this study were youth attending elementary(6<sup>th</sup> grade), middle(2<sup>nd</sup> grade), and high schools(2<sup>nd</sup> grade) belonging to the Busan Metropolitan City Office of Education. Depression was assessed using the BDI depression scale. Internet functions were classified into 10 categories, and the degree of use by Internet functions was examined. The most frequently used Internet sites were surveyed. Univariate analysis using X<sup>2</sup> test and multivariate analysis using logistic regression analysis were conducted to find out the difference of internet and smartphone media function on depression according to elementary, middle and high school students. Results: Depression was higher of 13.2 times for students who use online transactions (goods purchase), 0.07 times for students who use `bulletin board` activities in elementary students. Depression was higher of 1.55 times for those who use online transactions (purchasing goods), and 2.3 times for those who use adult sites for middle school students. Depression was higher of 2.1 times when using e-mail and 1.9 times when using other information retrieval for high school students. Conclusion: It is necessary to consider characteristics of internet utilizing pattern by school class in policy regulation and prevention program to reduce youth depression.
EPDM/Carbon Black계에서 Carbon Black에 따른기계적 성질 및 방진 특성
노태경 ( Tae Kyeong No ),강동국 ( Dong Guk Kang ),서재식 ( Jae Sik Seo ),양경모 ( Kyung Mo Yang ),서관호 ( Kwan Ho Seo ) 한국고무학회 2012 엘라스토머 및 콤포지트 Vol.47 No.3
본 연구에서는 EPDM 컴파운드에 여러 종류의 충전제를 사용하여 물리적, 기계적 특성을 관찰하였다. 충전제로는 Semi-reinforcing furnace black(SRF), high abrasion furnace black(HAF) 그리고 acetylene black을 사용하였다. 가교제로는 dicumyl peroxide (DCP)를 사용하였다. 레오미터, 경도계, 만능 재료 시험기, 영구 압축 줄음율그리고 동적 점탄성 분석을 통하여 재료의 성질을 관찰하였다. EPDM 컴파운드에 충전제로 SRF를 사용하였을 때함량의 증가에 따라 인장강도와 파단 연신율은 증가하였으나, acetylene black을 사용하였을 때 함량의 증가에 따라인장강도와 파단 연신율은 감소하였다. Acetylene black을 사용하였을 때 넓은 온도 범위에서 저장탄성률의 변화율이적었다. 또한 EPDM 컴파운드의 tan δ는 acetylene black을 사용하였을 때 우수한 결과를 보였다. This study measured the mechanical and damping properties of EPDM compounds including fillers. Semi-re-inforcing furnace black(SRF), high abrasion furnace black(HAF) and acetylene black were used as fillers. Dicumyl peroxide(DCP) were used as curing agents. The measurements were conducted using a moving die rheometer(MDR), durometer, universal testing machine(UTM), compression set and dynamic mechanical analysis(DMA). The tensile strength and elonga-tion at break increased with increasing SRF contents in EPDM compounds. However, they decreased with increasing the amount of acetylene black. In the inspecting temperature range, EPDM compound filled acetylene black had stable storagemodulus. Furthermore, the tan δ of the EPDM compounds obtained was enhanced by compounding with acetylene black.
이지영 ( Ji Young Lee ),권미순 ( Mee Soon Kwon ),추금숙 ( Keum Suk Chu ),조현웅 ( Hyun Ung Cho ),이정원 ( Jeoung Won Lee ),서재식 ( Jae Sik Seo ),송희종 ( Hee Jong Song ) 한국가축위생학회 2007 韓國家畜衛生學會誌 Vol.30 No.3
This is a case report on the occurrence of inclusion body hepatitis(IBH) and infectious bursal disease(IBD) among the broilers in a local farm located in Wanju, Jeollabukdo. Mostly IBH could be caused by adenovirus if the bird`s immune system was first weakened by exposure to immunosupressive agents such as infectious bursal disease virus(IBDV) and chicken anemia virus(CIAV). However IBH primary occurred before IBD in this case. And recent work has demonstrated that virulent adenovirus alone can produce the disease.