FDM 3D printing structures have rough surfaces and require post-treatment to improve the properties. Fumigation is a representative technique for removing surface unevenness. Surface treatment by fumigation proceeds by dissolving the surface of the protruding structure using a vaporized solvent. In this study, 3D printed PVB outputs are surface-treated with ethyl-alcohol fumigation. As the fumigation time increases, the surface flattens as ethanol dissolves the mountains on the surface of PVB and the surface valleys are filled with dissolved PVB. Through the fumigation process, the mechanical strength tends to decrease, and deformation rate increases. Ethanol vapor permeates into PVB, widening the distance between chains and resulting in weak bonding strength between chains. In order to confirm the effect of fumigation only, an annealing process is performed at 80 oC for 1, 5, 10, 30, and 50 minutes and the results of the fumigation are compared.

제주연안해역에 서식하고 있는 독가시치의 수중음에 대한 청각 특성을 파악하여 수중음을 이용한 음향 어법에 이용도를 높일 수 있는 기초자료를 제공할 목적으로 측정 주파수 80∼800Hz의 수중음과 7V의 직류 전압의 전기자극을 이용하여 음향 조건학습을 시킨 후 측정주파수와 음압을 임의로 변화시켜가면서 청각 문턱치를 구한 결과 독가시치는 측정주파수 80∼800Hz의 음을 인식하고 있었고, 측정주파수 80Hz, 100Hz, 200Hz, 300Hz, 500Hz, 800Hz에 대한 각각의 청각 문턱치는 102, 96, 92, 95, 105, 121dB로 나타났고, 측정주파수 200Hz에서 가장 낮은 음압 92dB를 나타내었으며, 측정주파수 800Hz에서 가장 높은 청각 문턱치를 나타내었다.

제주 연안역에 있어서 해양목장의 음향순치 대상 어종으로 선정할 수 있는 연안 정착성 어류인 쏨뱅이의 청각 능력을 파악할 목적으로, 임의의 순음과 전기자극을 이용하여 육상수조에서 조건 학습시킨 후, 주파수와 음압을 임의로 변화시켜가면서 쏨뱅이의 심전도를 도출하여 심박간격의 변화로부터 청각 문턱치 곡선을 구한 결과, 쏨뱅이는 실험에서 사용한 측정 주파수 80Hz～800Hz의 순음을 인식하고 있었다. 각 주파수에 대한 청각감도는 주파수 80Hz～200Hz에서는 민감하게 나타났으나, 주파수 500Hz 이상에서는 감도가 급격히 나빠지고 있었다. 청각 문턱치는 주파수 100Hz에서 약 90㏈ 의 음압으로 최소였으며, 주파수 300Hz 이상에서 급격하게 상승하는 경향을 보이면서 주파수 500Hz에서 약 127㏈의 음압으로 최고치를 나타내었다.

Recently, in our country has been heightened awareness of the performance of non-combustible construction materialsand eco-friendly. In addition, bottom ash can be used as a high-value, but it is a situation that is buried. Therefore, thebasic experimental study results on the development possibility of eco-friendly nonflammable floor finishing materialsusing the bottom ash, which is an industrial byproduct, are as follows: (1) As a test result of the compressive strengthof mortar conducted to review the use possibility of bottom ash as a floor finishing material, the standard mix that didnot use bottom ash showed 31.3MPa, a 25% replacement mix showed 33.7MPa and a 50% replacement mix showed33.6MPa. Consequently, higher results of the compressive strength of mortar were demonstrated up to the 50%replacement mix, compared to the standard mix. (2) As a flow test result by addition of superplasticizer, the flow was215mm in the 0.2% added mix, and 253mm in the 0.4% added mix. However, material separation was confirmed inthe case of the 0.4% added mix. Therefore, the addition meeting 190mm set forth in the KS F 4041 was 0.2%. (3) Asa result of bond strength test to review bond strength with concrete structure, it was 1.26MPa in case polymer powdercontent was 2%, except for 1.02MPa of basic mix, and it was 1.75MPa in the case of 4%, and all these met1.2MPaand more of bond strength set forth in the KS. (4) As a result of a wear resistance experiment conducted to review theuse possibility as a floor finishing material for parking lot, the mix meeting 0.15mg/mm2 or less of wear resistance setforth in the KS F 4041 was the case of 4% of polymer powder addition, which showed 0.13mg/mm2.