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저탄소 자동차용 강판의 레이저 용접성 및 평가에 관한 연구
정봉근,이창희,유순영,박인수 한국레이저가공학회 1998 학술발표대회 Vol.1998 No.1
조성과 두께가 다른 둘 이상의 part를 재단사가 재단하듯 만들 수 있다는 의미인 TB(Tailored Blank)는 1985년 Thyssen Stahl AG에 의해서 Au야 100의 floor pan에 처음으로 적용되었다. TB는 자동차 panel의 프레스 성형에 있어서 절단한 판재를 용접하여 하나의 결합소재로 일체화시켜 프레스 성형하는 기술로, 기존의 자동차 design은 판재를 절단하고 성형한 후에 spot 용접을 했는데 반해, TB는 판재를 절단하고 용접한 후에 성형하는 기술이다. 본 연구에서는 자동차 차체 강판에 사용되는 냉연강판(SPCEN)과 아연도금강판의 용접조건을 변화시켜 최적화시키고, 용접부의 야금학적 및 기계적 특성을 관찰하고자 한다.
울산 연안 해역 저서다모류 군집의 시·공간 변동 및 저서건강도 평가
정봉근,신현출 한국해양과학기술원 2018 Ocean and Polar Research Vol.40 No.4
This study was carried out to investigate benthic sedimentary environments and benthic polychaetous communities on the coast of Ulsan, located on the southern East Sea of Korea. This survey was conducted at 15 stations, four times seasonally in January, April, July and October 2016. From the coast to the outer sea, surface sediments turned into fine grained sediments. There were complex coarse-grained sedimentary facies in various forms in the coastal zones while those with mud facies were found in the offshore zone. Organic matter content (LOI) and sulfide amount (AVS) recorded extremely high values, and increased from the coast to the outer sea, showing a similar trend to mud content with depth. The benthic polychaetous community revealed a mean density of 525 ind./m2, and the total species number of species was 84. The major dominant polychaetous species were Magelona japonica, Lumbrineris longifolia and Heteromastus filiformis throughout the four seasons. Magelona japonica was concentrated predominantly in shallow coastal areas, but was present in all the regions of the survey area. Lumbrineris longifolia showed higher density in offshore regions more than 30 m deep, whereas H. filiformis showed higher density in coastal areas less than 30 m in depth. As a result of cluster analysis, the study area was divided into three ecological areas according to species composition, such as the northern coastal area between Ulsan Port- Onsan Port, the southern area around Hoeya River and the outer sea area. Benthic environments in the study area, as determined by AMBI and BPI index, maintained a healthy condition in all four seasons with the AMBI at a level above GOOD and BPI at a level above FAIR. As organic matter accumulation continues to take place in the Ulsan coastal area, it is essential that detailed research activities continue to be carried out and ongoing monitoring be maintained.