• Journal of Biomedical Engineering Research
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• v.41 no.4
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• pp.147-153
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• 2020

This study was to evaluate the usability of self-developed phantom for evaluating automatic exposure control (AEC) using three-dimensions (3D) printer. 3D printer of fused deposition modeling (FDM) type was utilized to make the self-developed AEC phantom and image acquisitions were conducted by two different type of scanners. The self-developed AEC phantom consisted of four different size of portions. As a result, two types of phantom (pyramid and pentagon shape) were created according to the combination of the layers. For evaluating the radiation dose with the two types of phantom, the values of tube current, computed tomography dose index volume (CTDIvol), and dose length product (DLP) were compared. As a result, it was confirmed that the values of tube current were properly reflected according to the thickness, and the CTDIvol and DLP were not significantly changed regardless of AEC functions of different scanners. In conclusion, the self-developed phantom by using 3D printer could assess whether the AEC function works well. So, we confirmed the possibility that a self-made phantom could replace the commercially expensive AEC performance evaluation phantom.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.04a
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• pp.70-79
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• 2003

Paper coating can give smoothness surface and good printability to uncoated paper. Macro roughness of base paper would be decreasing its groove and grit in view of side. Nevertheless its improving effect for paper, some kind of problem is showing in the fine coated paper. Especially, back trap mottle is one of serious problems in printing with fine coated paper. Printers can not adjust conditions to overcome the problem. Also large amounts of paper can be rejected. There are many factors that influence back trap mottle. However it is not clear what the important parameters are in back trap mottle. Back trap mottle has some relationship with ink setting but good guidelines are not clear. Back trap mottle has been linked to non-uniform ink setting. We do not know how much variation in setting we can tolerate. Other mottle issues such as micro-picking and ink refusal are still common. This paper was prepared to identify correlation with ink setting and delta ink density obtained from experiment and then tried to find out some relationships with ink setting and back trap mottle. Basically fine calcium carbonate and ciay was used for main components and coarse calcium carbonate was mixed in two fine pigments to change its porosity and ink acceptance. Micro ink tack force at KRK printing tester was adapted to measure ink setting rate. KRK units were used for back trap mottle simulation and two printed samples were prepared to check delta ink density. Clay base coating has more fast ink setting time than calcium carbonate's though smoothness of clay was better than calcium carbonate. It could be explained by that clay has finer pore in its coating than calcium carbonate. DID(delta ink density) has shown a good correlation with ink setting time from micro ink tack. The total pore volume of coating layer did not match with ink setting and DID. From the results we might conclude coating that has fine pore size around 0.05 ${\mu}m$ can be exposed to high possibility of back trap mottle.

• Fashion & Textile Research Journal
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• v.21 no.2
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• pp.133-140
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• 2019

This study developed smart fashion prototypes that provide utilitarian functionality by combining Fashion and Electronics regarding the IT focused convergence tendency in modern industries. A convergence R&D workshop was performed by Fashion design majors and Engineering majors for the study. As a result, 5 functional smart fashion prototypes were developed and the outline of each prototype are as follows. The $1^{st}$ prototype, 'Hidden Camera Detecting Coat' focused on gender-related crimes. The coat uses infrared lighting and LED technologies to provide a function to detect hidden cameras in suspicious public spaces such as toilets. The $2^{nd}$ prototype, 'Heating-massage Suit' targeted patients with musculoskeletal system difficulties. The suit uses heating and vibration technologies to provide a heating massage treatment for patients with ongoing difficulties in their daily lives. The $3^{rd}$ prototype is an air-bag jacket to prevent sexual molestation on public transportation. The jacket extends its volume through pressure sensing, air compressing, motors and 3D-printing technology to secure the wearer's personal preventive space between the user's body and others. The $4^{th}$ prototype is a town wear for people suffering from synesthesia. People with synesthesia inadvertently see colors when exposed to certain sounds. This town wear uses sound sensing, air compressing, motors and 3D-printing technology to provide sound prevention and a comfortable sound playing function. The $5^{th}$ prototype is a set of a vest and a gloves for visually impaired people. The vest and gloves uses DMS, voice playing, vibration technology to provide distance measuring and warning functions.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.799-806
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• 2000

Cu$_{6}$Sn$_{5}$-dispersed 63Sn-37Pb solder bumps of 760$\mu\textrm{m}$ size were fabricated on Au(0.5$\mu\textrm{m}$)/Ni(5$\mu\textrm{m}$)/Cu(27$\pm$20$\mu\textrm{m}$) BGA substrates by screen printing process, and their shear strength were characterized with variations of dwell time at reflow peak temperature and aging time at 15$0^{\circ}C$ . With dwell time of 30 seconds at reflow peak temperature, the solder bumps with Cu$_{6}$Sn$_{5}$ dispersion exhibited higher shear strength than the value of the 63Sn-37Pb solder bump. With increasing the dwell time longer than 60 seconds, however the shear strength of the Cu$_{6}$Sn$_{5}$-dispersed solder bumps became lower than that the 63Sn-37Pb solder bumps. The failure surface of the solder bumps could be divided into two legions of slow crack propagation and critical crack propagation. The shear strength of the solder bumps was inversely proportional to the slow crack propagation length, regardless of the dwell time at peak temperature, aging time at 150 $^{\circ}C$ and the volume fraction of Cu$_{6}$Sn$_{5}$ dispersion.> 5/ dispersion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.585-586
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• 2006

In this paper, we present a design, analysis, fabrication and performance test of the novel DoD metal-jet system for application to the high-density and high-temperature-melting materials. Based on the theoretical analysis, we design the metal-jet print head system and fabricate the metal-jet system, which can eject the droplet of lead-free metal solder in the high-temperature. In the experimental test, we set up the test apparatus for visualization of the droplet ejection and measure the Ejected droplet volume and velocity. As a result, the diameter, volume and the velocity of the ejected droplet are about $65-70{\mu}m$, 145-180 pl and 4m/sec. We also fabricate vertical and inclined 3D micro column structures using the present molten metal inkjet system. The measured geometries of the micro column structures are about height of $2,100{\mu}m$, diameter of $200{\mu}m$ and aspect ratio of 10.5 for vertical micro column and $1,400{\mu}m$ of height and $150{\mu}m$ of diameter for $65^{\circ}$-inclined micro column, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.5
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• pp.487-492
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• 2010

In this study, our system that the volume of collected human waste in the septic tank truck is measured accurately and the fee of disposing human waste can be calculated by using measured results has been developed. The level sensor and its circuits which can measure the height of the tank, the hand-held system that can be used by workers easily and simply with micro-controller have been developed. Also, this system has been built in the receipt printing function to charge for disposal fee. Even when working on a sloping field, this system can measure the accurate collected volume of human waste in the tank using the X-Y axis angle sensor. The results of this study expect that the popular complaints that generated from human waste can be reduced, the exportation possibility of our specialized systems can acquire foreign currency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1381-1387
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• 2007

Up to now, various continuous-processing systems are used in many industrial applications such as textile machines, paper-making machines, printing machines, and so on. In these applications, the tension forced on the products in the control volume can be changed according to the velocity difference between the feeding roll and the delivery roll. Specially, the tension variation generated by the velocity difference, or the inertial effect can decreases the quality of the products in the textile process. In this paper, the tension control problem in a circular knitting machine system is treated to cope with these problems. Firstly, the tension relationship in the winding mechanism of general continuous-processing systems is modeled. Next, to effectively drive the feeding and delivery rolls in the circular knitting machine system, a new tension control method is presented by considering the inertia compensation and the velocity difference between the feeding roll and the delivery roll. Through the experimental works, it is shown that the proposed tension control method can be used to improve the performance of tension control in the control volume of the given circular knitting machine system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.345-349
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• 2019

The National Aeronautics and Space Administration (NASA) has long been studying the essential elements of manned planetary exploration and has held several international challenges to encourage the research works related to it. One of them was the NASA Centennial Challenge Programs which started in 2015. Following the second in 2017, the third is currently going on in 2019. Participating "3D-Printed Habitat Challenge", one of the challenges in the second program, this research team designed and developed the 3D printer extruding module for the Lunar Simulant (Korea Hanyang Lunar Simulant-1; KOHLS-1) and the polymer. For optimizing the modul, a cylindrical specimen of ${\varnothing}150{\times}300mm^3$ volume and a specimen of $200{\times}100{\times}650mm^3$ volume were manufactured and their compressive and flexural strengths were tested. The findings can help automatize the space construction in the future.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.685-692
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• 2024

Currently used heating elements are metal and non-metal heating elements, including various types of heaters, and resistance line heating elements have a problem of decreasing thermal efficiency over time, so to solve this problem, a planar heating element using high-purity carbon materials and oxidation-resistant inorganic compounds was applied. Through the manufacture of planar heating elements using CNT, ruthenium composite materials, and ruthenium oxide, physicochemical performance and capacity were increased, and instantaneous responsiveness was increased. Through thick film technology applicable to various base bodies, fine patterns were formed by the screening method in consideration of the fact that the performance of the heat source depends on the viscosity and pattern shape. The heating element was manufactured by thick film printing technology by mixing ruthenium oxide, CNT, Ag, etc. The characteristics of each paste were analyzed through viscosity measurement, and STS 430 was used as a base. Surface temperature and efficiency were measured by testing heaters manufactured for small wind tunnels and real-vehicle experiments. The surface temperature decreased as the air volume increased, and the optimal system boundary was found to be about 200 mm. Among the currently used heating elements, this paper manufactured a planar heating element using thick film technology to find out the relationship between air volume and temperature, and to study the surface temperature.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.41-48
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• 2001

This paper was made to evaluate the effect of the type of latex for coating on the printability by investigating the structure of pore such as the pore fraction, the number of pores, pore size and distribution of coated paper. The coated structure is mainly depend on the results of interaction between pigment and binder. It means that the structure of pore formed is chiefly affected by the type of latex. This physical properties of pore have a close relation with ink set-off associated with the drying rate, the speed of penetration of ink into base paper and printing gloss. Therefore it was necessary to find out the relationship between pore structure and the performance of printability by modifying the type of latex to vary the pore structure of coated paper. Acrylic latex was superior to S/B latex in the sedimentation volume, compressibility, smoothness, pore fraction and its number, the weight of transferred ink onto the coated paper and ink repellance. In contrast, water retention and ink setting were not good. in the comparison of anionic and amphoteric latex, amphoteric latex showed better performance in the thickness, smoothness, pore fraction and its number, pore size, the weight of ink transmitted and K&N ink receptivity, etc.