Nersisyan H.H.,Chungnam National University |
Journal of Materials Processing Technology | Year: 2013
In this study, intermetallic compound formation at the interface between aluminum and copper during hydrostatic extrusion was simulated by performing a solid state diffusion bonding experiment with various processing parameters, including bonding temperature and pressure and holding time, and by inserting an Ag colloid layer between the aluminum and copper. Regression equations were developed to predict thickness of diffusion layer and interface hardness. An intermetallic compound formed at the interface between the Al and Cu during diffusion bonding at 420°C and 240 MPa for 60 min, and it was effectively controlled by inserting an Ag colloid. These experimental data will be useful for setting up processing parameters to prepare Al/Cu matrix composite materials by using hydrostatic extrusion. © 2012 Elsevier B.V.
Kim K.-H.,KITECH |
Optics Express | Year: 2016
We present the light-controlled hierarchical mechanical properties of optically patterned azobenzene thin films through a nanoindentation study. In this study, we inscribed holographic surface relief grating (SRG) of azopolymers by two-beam coupling-based light interference lithography. The resultant morphological profile of azopolymers was monitored by atomic force microscope (AFM), followed by the nanoindentation study. From the load-displacement curve of the indentation procedure, photomechanical changes of the azopolymers along grating patterns were evaluated in terms of hardness and modulus at the crest and trough of the SRG, respectively. The results revealed that the surface height as well as the mechanical properties was modulated according to the light interference pattern. ©2016 Optical Society of America.
Lim T.-B.,KITECH |
Lim T.-B.,Sungkyunkwan University |
Cho K.H.,KITECH |
Kim Y.-H.,Sungkyunkwan University |
Optics Express | Year: 2016
We presented enhanced light extraction efficiency of organic light emitting diodes (OLEDs) cells with a nano-sized diffraction grating layer. Various diffraction gratings of different morphologies including linear, cubic, hexagonal and quasiperiodic patterns were fabricated by multiplexing light interference exposure on an azobenzene thin film. The effect of diffraction grating layer on device performances including luminous properties and quantum efficiency was investigated. In contrast to periodic grating patterns, the quasiperiodic structures leading broadband light extraction resulted in improved external quantum efficiency and power efficiency by 73% and 63%, respectively, compared to conventional OLED with flat surface of glass substrate. ©2016 Optical Society of America.
Chang H.N.,KAIST |
Jung K.,KAIST |
Choi J.-D.-R.,KAIST |
Choi J.-D.-R.,GS Caltex Corporation |
And 2 more authors.
Biotechnology Advances | Year: 2014
A multi-stage continuous high cell density culture (MSC-HCDC) system makes it possible to achieve high productivity together with high product titer of many bioproducts. For long-term continuous operation of MSC-HCDC systems, the cell retention time and hydraulic retention time must be decoupled and strains (bacteria, yeast, plant, and animal cells) must be stable. MSC-HCDC systems are suitable for low-value high-volume extracellular products such as fuel ethanol, lactic acid or volatile fatty acids, and high-value products such as monoclonal antibodies as well as intracellular products such as polyhydroxybutyric acid (PHB), microbial lipids or a number of therapeutics. Better understanding of the fermentation kinetics of a specific product and reliable high-density culture methods for the product-generating microorganisms will facilitate timely industrialization of MSC-HCDC systems for products that are currently obtained in fed-batch bioreactors. © 2014.
Kim T.-Y.,Hanyang University |
Hwang J.-Y.,KITECH |
Moon S.-J.,Hanyang University
Japanese Journal of Applied Physics | Year: 2010
The spectral optical properties of the silver/copper nanoparticle ink at visible and near-infrared wavelength were measured by ellipsometry. The purpose of the measurement of the optical properties is to select the optimal process parameters such as working wavelength and laser incidence angle by finding the maximum absorption wavelength. The reflectance and absorptivity of the nano-ink including silver/copper nanoparticles were calculated from the experimentally obtained refractive indices. The absorptivity has been maximized at the green wavelength for the normal incident angle to the target at the initial stage of the curing. Therefore, a continuous wave green laser at the wavelength of 532nm is chosen for the laser curing. For the laser curing process, the inkjet-printed silver/copper nano-ink samples on the glass and poly(ethylene terephthalate) (PET) substrates are adopted to find the effect of the substrate materials on laser curing process. The used laser energy is 31.62 and 177.27W/ cm2 to analyze the effect of the laser intensity on laser curing process. The nano-ink on the PET substrate has lower specific resistance than that on the glass substrate with the identical laser irradiation time. The higher laser intensity is recommended to obtain the lower specific resistance with same laser irradiation. Compared with the 30-min furnace curing process at the temperature of 250 °C, a few seconds laser curing process can be effectively adopted with appropriate scanning system to shorten the curing time. © 2010 The Japan Society of Applied Physics.
Lee G.-B.,KITECH |
Ko M.-J.,KITECH |
International Journal of Precision Engineering and Manufacturing | Year: 2012
Recently, development of renewable energy and improvement of energy efficiency become important issues due to high oil price and global warming. The improvement of energy efficiency restrains the growth rate of energy demand to result in delaying or reducing the expansion of energy supply facilities. As most of energy consumption occurs in industries, it is natural that various methods are sought for energy savings through an efficient management of energy resources consumed in shop floors of industries. In this paper the Energy Resource Management (ERM) system is proposed efficiently to manage and analyze energy consumption and CO 2 emission in industries. Data of energy consumption are measured in real time by means of electric power meters and stored in the ERM system by using Machine-to-Machine (M2M) devices. Energy efficiency of a manufacturing process is analyzed based on the data. In this paper the system is implemented in the inner scrubbing process and drilling process for manufacturing PCB and the reflow soldering process for surface mounting of chips or devices on PCB. The results obtained from the implementation are analyzed and reviewed to check usefulness and reliability of the ERM system. The ERM system proposed in this paper mainly for monitoring and analysis of energy consumption can be utilized as the guidelines to manage and improve the energy efficiency in manufacturing processes. © KSPE and Springer 2012.
Kim J.-D.,KITECH |
Kim H.-K.,KITECH |
Heo Y.-M.,KITECH |
Advanced Materials Research | Year: 2012
In this paper, the relation between die roll height and V-ring position was studied by fine blanking experiments for imaginary special automobile seat recliner gear. The three die inserts and three guide plate inserts with different V-ring positions were machined, and fine blanking tool was manufactured. Using the fine blanking tool, three experiments were conducted on the 650 ton fine blanking press. Each die roll height was measured, analyzed and we found the tendency of die roll heights on imaginary special gear to increase with increasing the distance between V-ring position and contour of gear. This result can be used to minimize the die roll height of fine blanking gear parts when designing V-ring of fine blanking tool.
Communications in Computer and Information Science | Year: 2012
We, KITECH, had developed CAE software for casting industries(foundries) over last 10 years, and distributed the developed CAE package for foundries in south korea. But the gorwth rate of market for CAE technologies becomes slower because of expensive prices of CAE tools and lacks of trials for introducton of new technologies into their manufacturing workplaces. So that we have been developing new concept market for CAE tehcnologies for last 5 years, and built cloud platform services for CAE in south korea, and it is ISC(Internet Simulation Center). We setup cluster computing systems, datacenter for infrastructure, and developed various services and relational interfaces to serve cloud computing services. So that we have loaded 4 CAE contents into our cloud computing platform, and are providing CAE services to domestic users. © 2012 Springer-Verlag.
Kim J.-D.,KITECH |
Applied Mechanics and Materials | Year: 2012
In this paper, the relation between die roll height and V-ring position of a fine blanking tool was studied by experimenting on a special part with various corner shapes. Three guide plate inserts with different V-ring positions and a die insert with constant die chamfer were machined, and a fine blanking tool was manufactured for the fine blanking experiments. Three experiments were conducted on a 650-ton fine blanking press. Each die roll height was measured and analyzed. We found the tendency of the die roll heights on the corner shapes of fine blanked parts to increase with increasing the distance between the V-ring position and the contour of the special part, and to decrease with increasing corner radius and angle. These results can be used to minimize the die roll height of fine blanking parts with corner shapes when designing the V-ring of a fine blanking tool. © (2012) Trans Tech Publications, Switzerland.
Applied Mechanics and Materials | Year: 2013
In this paper, a change of die roll height according to the die chamfer shape and V-ring distance of a fine blanking tool was studied by experiments on a special part with various corner shapes. Three guide plate inserts with different V-ring positions and three die inserts with different die chamfers were machined, and then a fine blanking tool was manufactured for the fine blanking experiments. Nine experiments were conducted on a 650-ton fine blanking press. Each die roll height was measured and analyzed. It would be noticed that the die roll heights on the corner shapes of the fine blanked parts increased with increasing V-ring distance and die chamfer angle, but it decreased with increasing corner radius and angle. The results in this study can be used to minimize the die roll height of fine blanked parts with corner shapes when designing the V-ring and die chamfer of a fine blanking tool. © (2013) Trans Tech Publications, Switzerland.