Powder characteristics, such as density, size, shape, thermal properties, and surface area, are of significant importance in the powder bed fusion (PBF) process. The powder required is exclusive for an efficient PBF process. In this study, the particle size distribution suitable for the powder bed fusion process was derived by modeling the PBF product using simulation software (GeoDict). The modeling was carried out by layering sintered powder with a large particle size distribution, with 50 μm being the largest particle size. The results of the simulation showed that the porosity decreased when the mean particle size of the powder was reduced or the standard deviation increased. The particle size distribution of prepared titanium powder by the atomization process was also studied. This study is expected to offer direction for studies related to powder production for additive manufacturing.

다양한 이미지 샘플의 Eye test를 바탕으로 기술적인 화질 지표 조절을 통하여 감성 화질을 최적화 시키는 방법이 소개된다. 여러 가지 이미지 콘텐츠의 다양한 이미지에 대하여, 콘트라스트, 명도, 채도 화질 지표 톤 커브를 사용하여 평가가 수행 되었다. 이미지 화질 향상에 기여하는 우선순위는 명암, 채도 및 밝기 순으로 분석 되었다. 이미지 감성 화질 측정치의 기술적인 화질 지표 변화에 따른 기울기의 공통점을 살펴본 결과, 거의 0, 중간 그리고 최대 기울기의 영역으로 구성된 함수 형태로 모델링을 할 경우, 기존의 역 U 형태의 성질 뿐 아니라 log 또는 포화 형태의 감성 화질 변화까지 분석 가능함을 알 수 있었다. 단일 및 복수의 화질 지표의 경우에 대하여도 화질 개선 방안이 모색 되었으며, 기존 및 본 논문에서 분석된 결과를 위한 새로운 함수가 소개 되었다. 복수의 통합적 이미지 화질 지표를 통하여 향상 시킬 경우 오직 몇몇 한정된 지표 제어의 경우에만 실현 가능하다는 것을 알 수 있었다. 또한, 화질 향상 방법은 영상 콘텐츠에 따라 크게 차이가 없음을 알 수 있었다.

The study for reducing friction in elevation motion of a large television stand using over 50 inches is performed in this paper. The first study attempted to reduce the frictional force the gas seal lip technology. The second study is for optimized piston structure development by comparison pipe orifice and labyrinth orifice. As the result of the first study, in the gas seal lip technology, the outer-inner diameter of Ø20 × Ø8 in the test result of hollow rod is revealed more proper if the weight of 50 inch television assumed as 30. As the result of the second study, the optimized piston structure development through experiment is fixed orifice specification as labyrinth orifice because pipe orifice is founded slip up/down phenomenon of the Ø0.4~1.0 orifice and the labyrinth orifice is not founded that of the Ø0.4~0.6 orifice both tests on 300 mm intervals.

PURPOSES : This study is to suggest time to spray curing compound, the amount of curing compound, and the number of times to spray curing compound based on indoor tests. METHODS : Based on the literature review, two methods are used in this study, One is test for water retention of concrete curing material and the other is test for abrasion resistance of concrete surfaces by the rotating-cutter method. Through those methods, curing compound was evaluated. RESULTS : The result of the laboratory experiment for time to spray curing compound indicates that 30 minutes after placing concrete is optimal. For the amount of curing compound, 0.5l/m2 is the minimum quantity for both concretes. Through test of the number of times to spray curing compound, method to spray the whole amount of curing compound in twice is more efficient than it to spray the whole amount at a time. Also, method of separately 30-50 minutes spray is better than method of separately 10-30 minutes spray. CONCLUSIONS : From the testing results, it can be proposed that optimum time to curing compound is 30±15 minutes, 0.5l/m2 is efficient for spraying the whole amount of curing compound at a time, and 0.4l/m2 is the best for spraying the whole amount of curing compound in twice, which sprays it in 20 minutes after 30 minutes from placing concrete.

최근 수년간 팽이버섯 농가에서 팽이버섯 배양시 기중균사로 인해 타공구멍이 막히고, 갓의 모양이 기형을 보이며, 수확량이 30% 정도 줄어드는 증상이 발생되어 농가에 막대한 피해를 주어 왔는데, 주요원인으로 균주의 이상으로 추정되고 있어, 이를 조기에 검출하는 기술개발이 요구되어 왔다. 이에 본 실험에서는 농가수준에서 쉽고 빠르게 균주의 건전성 유무를 판단할 수 있는 방법을 개발하고자 하였다. 선행연구로 지시약과 탄소원을 달리하여 변색정도로 퇴화균주를 검출하는 기술을 개발하였고, 추가적으로 다양한 수종을 사용하여 최적의 방법을 도출하고자 하였다. 검사대상이 되는 균주가 저온에 노출되었을 경우를 가정하여 배양이 완료된 후 4℃에 보관한 균주와 25℃생육중인 균주를 사용하였다. YP배지를 기본으로 하고 톱밥종류를 포플러, 강참, 미송 등 7종을 사용하였으며, 배지분주시 고른 분포를 위하여 분쇄하여 60 mesh의 체를 통과시며 사용하였다. 사용한 수종중 포플러 톱밥에서 건전균주와 섹토링이 나타나는 생산량 감소 이상균주의 색깔변화차이가 가장 많이 났다. 그 외 이상증상이 타공구멍이 막히는 정도의 경미한 이상균주는 균주마다 색깔변화가 일정하지 않았다. 배양후 일정기간 저온(4℃)에 보관된 균주가 상온(25℃)에 자라는 균주보다 정상균주와 이상균주의 색깔변화 차이가 뚜렷하였다.

In this paper, an experimental study on the data compression sensing technique optimized by Northridge earthquake waveform was performed to efficiently obtain the dynamic response of the civil structure. The optimized compression sensing technique is embedded in the wireless sensing system. Also, the dynamic response(acceleration) of the cable-stayed bridge model was acquired and the validity of the compression sensing technique was evaluated. The data compression sensing technique optimized by Northridge earthquake waveform was able to efficiently obtain the dynamic response of a flexible civil structure under 10Hz.

In this paper, an experimental study on the data compression sensing technique optimized by El-centro earthquake waveform was performed to efficiently obtain the dynamic response of the civil structure. The optimized compression sensing technique is embedded in the wireless sensing system. Also, the dynamic response(acceleration) of the cable-stayed bridge model was acquired and the validity of the compression sensing technique was evaluated. The data compression sensing technique optimized by El-centro earthquake waveform was able to efficiently obtain the dynamic response of a flexible civil structure under 10Hz.

In this paper, an experimental study on the data compression sensing technique optimized by Kobe earthquake waveform was performed to efficiently obtain the dynamic response of the civil structure. The optimized compression sensing technique is embedded in the wireless sensing system. Also, the dynamic response(acceleration) of the cable-stayed bridge model was acquired and the validity of the compression sensing technique was evaluated. The data compression sensing technique optimized by Kobe earthquake waveform was able to efficiently obtain the dynamic response of a flexible civil structure under 10Hz.