• 한국분말재료학회지
• /
• 제20권4호
• /
• pp.308-312
• /
• 2013

In this paper, we describe experiment results using a vibration assisted hybrid femtosecond laser (${\lambda}$:795 nm) ultra-precision machining system. The hybrid system we have developed is possible that optical focal point of the femtosecond laser constantly and frequently within the range of PZT(piezoactuator) vibrator working distance. Using the hybrid system, We have experimented on brass and studied about differences of result of hole aspect ratio compare to general experiment setup of femtosecond laser system. Aspect ratio of a micro hole on brass is increased as 54% with 100 Hz vibration frequency and surface roughness of the side wall also improved compare to non-vibration.

• 한국주조공학회지
• /
• 제32권6호
• /
• pp.269-275
• /
• 2012

Al-Mg-Si/Al hybrid alloy was prepared by Duo-casting and the mechanical behavior was evaluated based on their microstructure and mechanical properties. The hybrid aluminum alloy included the Al-Mg-Si alloy with fine eutectic structure, pure Al with the columnar and equiaxed crystals, and the macro-interface existing between Al-Mg-Si alloy and pure Al. The growth of columnar grains in pure Al occurred from the macro-interface. The tensile strength, 0.2% proof stress and bending strength of the hybrid aluminum alloy were almost similar to those of pure Al, and the elongation was much higher than the Al-Mg-Si alloy. The fracture of the hybrid alloy took place in pure Al side, indicating that the macro-interface was well bonded and the mechanical behavior strongly depends on the limited deformation in pure Al side.

• 한국표면공학회지
• /
• 제44권4호
• /
• pp.155-164
• /
• 2011

Electron beam evaporation source is widely used to prepare thin films by physical vapor deposition because it is very effective to vaporize materials and there is virtually no limit to vaporize materials including metals and compounds such as oxide. In this study, evaporation characteristics of various metals and compounds from an electron beam evaporation source have been studied. The 180 degree deflection type electron beam evaporation source which has 6-hearth crucibles and is capable of inputting power up to 10 kW was employed for evaporation experiment. 36 materials including metals, oxides and fluorides have been tested and described in terms of optimum crucible liner, evaporation state, stability, and so on. Various crucible liners have been tried to find out the most effective way to vaporize materials. Two types of crucible liners have been employed in this experiment. One is contact type liner, and the other is non-contact type one. It has been tried to give the objective information and the most effective evaporation method on the evaporation of materials from the electron beam evaporation source. It is concluded that the electron beam evaporation source can be used to prepare good quality films by choosing the appropriate crucible liner.

• Bulletin of the Korean Chemical Society
• /
• 제23권6호
• /
• pp.884-890
• /
• 2002

An inorganic-organic hybrid system, silica-poly(ethylene glycol) songel is reported. This system was prepared via sol-gel method by varying varous processing variables. e.g. ultrasonic radiation time, gelling temperanture, PEG content and its molecular weight. Various experimental techniques wee employed to analyze the morphological, mechanical and optical properties of the system. The results were discussed in the light of existing theories. The sonogel system exhibited the common features of inorganic-organic hybrids. $SiO_2-10$ wt% PEG sonogel exhibited the morphological and optical properties superior to those reported earlier for the classic gels and found suitable for device applications.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.251.2-251.2
• /
• 2013

Natural photosynthesis utilizes two proteins, photosystem I and photosystem II, to efficiently oxidize water and reduce NADP+ to NADPH. Artificial photosynthesis which mimics this process achieve water splitting through a two-step Z-schematic water splitting process using man-made synthetic materials for hydrogen fuel production. In this study, Z-scheme system was achieved from the hybrid materials which composed of hydrogen production part as photosystem I protein and water oxidizing part as semiconductor BiVO4. Utilizing photosystem I as the hydrogen evolving part overcomes the problems of existing hydrogen evolving p-type semiconductors such as water instability, expensive cost, few available choices and poor red light (>600 nm) absorbance. Some problems of photosystem II, oxygen evolving part of natural photosynthesis, such as demanding isolation process and D1 photo-damage can also be solved by utilizing BiVO4 as the oxygen evolving part. Preceding research has not suggested any protein-inorganic-hybrid Z-scheme composed of both materials from natural photosynthesis and artificial photosynthesis. In this study, to realize this Z-schematic electron transfer, diffusion step of electron carrier, which usually degrades natural photosynthesis efficiency, was eliminated. Instead, BiVO4 and Pt-photosystem I were all linked together by the mediator gold. Synthesized all-solid-state hybrid materials show enhanced hydrogen evolution ability directly from water when illuminated with visible light.

• Elastomers and Composites
• /
• 제57권4호
• /
• pp.197-204
• /
• 2022

Recently, the demand has increased for protective clothing materials capable of shielding the wearer from bullets, fragment bullets, knives, and swords. It is therefore necessary to develop light and soft protective clothing materials with excellent wearability and mobility. To this end, research is being conducted on hybrid design methods for various highly functional materials, such as carbon nanotube (CNT) sheets, which are well known for their low weight and excellent strength. In this study, a hybrid protective material using CNT sheets was developed and its performance was evaluated. The material design incorporated a bonding method that used a binder for interlayer combination between the CNT sheets. Four types of binders were selected according to their characteristics and impregnated within CNT sheets, followed by further combination with aramid fabric to produce the hybrid protective material. After applying the binder, the tensile strength increased significantly, especially with the phenoxy binder, which has rigid characteristics. However, as the molecular weight of the phenoxy binder increased, the adhesive force and strength decreased. On the other hand, when a 25% lightweight-design and high-molecular-weight phenoxy binder were applied, the backface signature (BFS) decreased by 6.2 mm. When the CNT sheet was placed in the middle of the aramid fabric, the BFS was the lowest. In a stab resistance test, the penetration depth was the largest when the CNT sheet was in the middle layer. As the binder was applied, the stab resistance improvement against the P1 blade was most effective.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
• /
• pp.359-362
• /
• 2005

Self diagnosis monitoring system is defined as concrete structural carbon and glass hybrid fiber materials, in response to the change in external disturbance and environments, toward structural safety and serviceability as well as the extension of structural service life. In this study, carbon and glass hybrid fiber materials were investigated fundamentally for the applicability of self diagnosis in smart concrete structural system as embedded functions of sensors.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.8-9
• /
• 2006

Hybrid atomization is a new atomization technique that combines gas atomization with centrifugal atomization. This process can produce fine, spherical powders economically with a mean size of about 10 m diameter and a tight size distribution.

• 한국기계가공학회지
• /
• 제9권2호
• /
• pp.1-5
• /
• 2010

According to the high demand of hybrid components, the hybrid materials development and processing technology were increased in the industry field. Although hybrid materials have various machining technologies, the research about them has rarely been proceed. This study is to carry out results about design technology of miniaturized high-speed air spindle and machining characteristics of hybrid materials using that. We studied machining characteristics in Nickel-Chrome alloy(Ni-Cr) according to change rotating speed using miniaturized high-speed air spindle. As the following results, the change of surface shape and roughness was investigated as the processing conditions such as rotating speed of miniaturized high-speed air spindle.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
• /
• pp.527-533
• /
• 2004

Utilization of new lighter materials, more tough and durable than existing materials, is getting larger in recent constructions. FRP, stronger and lighter than present materials, can be formed in various shapes and has high durability, which makes it more profitable as a new material in construction fields. However, effort to use FRP in real construction is toddling and FRP is used primarily as reinforcing material in connote structure. We are about to develop Hybrid FRP Rod for the development of advanced construction material which is based on IT, by Hybridization of HIP, spotlighted as new construction material, and optical sensor in smart measurement. Beforehand, it is required to fully understand the properties of tension test operated in Hybrid FRP Rod. For this, a specimen was made by hybridization of FRP Rod and FBG sensor. Strain of Hybrid FRP Rod was measured comparing electric sensor and FBG sensor.