본 연구는 8종의 생약 복합추출물인 Derma Genie™-DLP121의 피부 건강 개선 효능을 확인하 고자 하였다. 이를 위해, in vitro model에서 Derma Genie™의 생리 활성 정도를 평가했으며, 4종의 피부 세포 내 항산화, 항염, 보습 증진, 주름 개선 및 미백 효능을 분석하였다. 실험 결과, Derma Genie™에는 22.577 mg GAE/g의 폴리페놀이 함유되었고, DPPH assay에서는 최대 74.947%의 radical 소거능을 보였 다. Lipopolysaccharide를 처리하여 과염증 반응을 유도한 RAW 264.7 세포에서는 Derma Genie™가 산 화 질소(NO) 뿐만 아니라, 3종의 염증성 사이토카인(Il-6, Il-1β, Tnf-α)의 농도 의존적인 감소 효과를 매개하여 상당한 항염 효능이 있음을 입증하였다. 또한 Derma Genie™는 히알루론산을 생성하는 효소인 HAS1 및 HAS2의 유전자 발현은 증가시키고, 히알루론산 분해 효소 HYAL1의 발현은 저해시켜 세포 내 보습 증진 효능을 나타내었다. 뿐만 아니라, ultraviolet B (UVB)에 의한 세포 생존율 감소 및 주름 연관 유전자(COL1A1, COL3A1)의 발현 감소가 Derma Genie™ 처리 시 개선됨을 확인하였다. 특히 최대 농도 의 Derma Genie™ (1 mg/mL)와 UVB를 병용 처리한 군에서 주름 연관 인자인 COL1A1 및 COL3A1의 발현량이 각각 55.080 및 57.103% 개선됨을 보였다. 마지막으로, α-MSH로 멜라닌 합성을 유도시킨 B16F10에서 Derma Genie™의 병용 처리는 세포 내 멜라닌 함량을 최대 95.159% 감소시켰다. 이는 Derma Genie™가 세포 내 tyrosinase 활성을 억제함으로써 미백 효능을 가지는 것으로 판단되었다. 따라 서 이러한 결과는 Derma Genie™가 피부세포 내 항산화, 항염, 보습 증진, 주름 개선 및 미백 효능이 존재 함을 보여주며, 피부건강 증진을 위한 신규 기능성 화장품 원료로의 활용 가능성을 제고하였다.

In this study, a spray dryer is used to make granules of Y2O3 and YF3, and then Y5O4F7 is synthesized following heat treatment of them under Ar gas atmosphere at 600 oC. Single and binary monomer mixtures are compared and analyzed to optimize photocurable monomer system for DLP 3D printing. The mixture of HEA and TMPTA at 8:2 ratio exhibits the highest photocuring properties and low viscosity with shear thinning behavior. The optimized photocurable monomer and synthesized Y5O4F7 are therefore mixed and applied to printing process at variable solid contents (60, 70, 80, & 85 wt.%) and light exposure times. Under optimal light exposure conditions (initial exposure time: 1.2 s, basic exposure time: 5 s), YOF composites at 60, 70 & 80 wt.% solid contents are successfully printed. As a result of measuring the size of the printed samples compared to the dimensions of the designed bar type specimen, the deviation is found to increase as the YOF solid content increases. This shows that it is necessary to maximize the photocuring activity of the monomer system and to optimize the exposure time when printing using a high-solids ceramic slurry.

The 3D printing process provides a higher degree of freedom when designing ceramic parts than the conventional press forming process. However, the generation and growth of the microcracks induced during heat treatment is thought to be due to the occurrence of local tensile stress caused by the thermal decomposition of the binder inside the green body. In this study, an alumina columnar specimen, which is a representative ceramic material, is fabricated using the digital light process (DLP) 3D printing method. DTG analysis is performed to investigate the cause of the occurrence of microcracks by analyzing the debinding process in which microcracks are mainly generated. HDDA of epoxy acrylates, which is the main binder, rapidly debinded in the range of 200 to 500oC, and microcracks are observed because of real-time microscopic image observation. For mitigating the rapid debinding process of HDDA, other types of acrylates PETA, PUA, and MMA are added, and the effect of these additives on the debinding rate is investigated. By analyzing the DTG in the 25 to 300oC region, it is confirmed that the PETA monomer and the PUA monomer can suppress the rapid decomposition rate of HDDA in this temperature range.

In the development of advanced ceramic tools, material improvements and design freedom are critical in improving tool performance. However, in the die press molding method, many factors limit tool design and make it difficult to develop innovative advanced tools. Ceramic 3D printing facilitates the production of prototype samples for advanced tool development and the creation of complex tooling products. Furthermore, it is possible to respond to mass production requirements by reflecting the needs of the tool industry, which can be characterized by small quantities of various products. However, many problems remain in ensuring the reliability of ceramic tools for industrial use. In this study, alumina inserts, a representative ceramic tool, was manufactured using the digital light process (DLP), a 3D printing method. Alumina inserts prepared by 3D printing are pressurelessly sintered under the same conditions as coupon-type specimens prepared by press molding. After sintering, a hot isostatic pressing (HIP) treatment is performed to investigate the effects of relative density and microstructure changes on hardness and fracture toughness. Alumina inserts prepared by 3D printing show lower relative densities than coupon specimens prepared by powder molding but indicate similar hardness and higher fracture toughness values.

In this study, a process is developed for 3D printing with alumina (Al2O3). First, a photocurable slurry made from nanoparticle Al2O3 powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6- trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of Al2O3 is determined by measuring the rheological properties of the slurry. Then, green bodies of Al2O3 with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed Al2O3 green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that Al2O3 products of various sizes and shapes can be fabricated by DLP 3D printing.

The aim of this study is to investigate the effect of wear resistance with 3D printing of DLP(Digital Light Processing). For this purpose, three wear factor which are wear loss, coefficient of friction and friction force applied to test wear-resistance. Wear test of ball-on-disk has been performed using steel balls to determine the variation of wear characteristics. Finally, the coefficient of wear was calculated by the Archard wear equation with 3D printing of DLP.

볼륨 타입의 컬러 홀로그래픽 스테레오그램을 디지털 방식으로 제작하기 위해 광학 시스템에 대해 연구하였다. 필름으로 노광하는 기존의 과정과 비교해 간략화하고 자동화된 볼륨 컬러 홀로그램의 제작을 위해 DLP 프로젝트를 도입하여 광학시스템을 디자인했다. DLP 프로젝트를 이용하여 시차 이미지를 확산판에 투영하고 물체광을 생성시켰다. 참조광은 유제면의 반대 방향으로 입사시켜 간섭무늬를 만들었다. 시차이미지는 색분해 하여 Red, Green, Blue의 색 성분으로 만들어 공간에서 분할하는 기록 방법으로 컬러 홀로그래픽 스테레오그램을 제작했다. 660nm, 532nm, 457nm의 파장을 지닌 세 대의 레이저 광원을 사용해 컬러 홀로그래픽 스테레오그램을 2단계로 나누어 기록했다. 마스터 홀로그램에서 공액 재생법으로 실상을 재생시켜 리프만 홀로그램 타입으로 제작하였다. 제안하는 디지털 방식의 광학 시스템으로 볼륨 타입의 컬러 홀로그래픽 스테레오그램을 실현 가능하다는 것을 확인하였다.