• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.81-85
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• 2020

Shaving dust is a collagen fiber that is the leather waste occurred for thickness adjustment during the natural leather manufacturing process, and causes problems such as an environmental contamination because of a chromium (Cr) contained when it comes to reclaiming process. Various studies applying the shaving dust are currently being conducted in many countries across the world with an initiative by the EU. Of those applications, the bonded leather is being highlighted as a substitute for natural leather. Since the bonded leather, however, uses latex as a binder, accordingly it entails a high weight and a poor ventilation, which are deemed as disadvantages due to its dense internal tissues compared to other synthetic leathers. To address such disadvantages, this study employed the thermally expandable micro sphere to improve its air permeability and light weight by alleviating the internal structure. This is a study on the manufacturing of light bonded leather using the shaving dusts. In the study, the shaving dusts were forced to foam under 100~120℃ considering the heat resistance of collagen fiber after applying the thermally expandable micro sphere, and then the tendency was analyzed. In the analysis results, the most excellent foaming rate was exhibited when the shaving dusts were treated under 120℃ for 8 minutes and the variation of internal structure according to a foaming was observed through SEM analysis for the cross-section of the bonded leather.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.941-946
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• 2002

Both Cu and Cu-oxide nanopowders have great potential as conductive paste, solid lubricant, effective catalysts and super conducting materials because of their unique properties compared with those of commercial micro-sized ones. In this study, Cu and Cu-oxide nanopowders were prepared by Pulsed Wire Evaporation (PWE) method which has been very useful for producing nanometer-sized metal, alloy and ceramic powders. In this process, the metal wire is explosively converted into ultrafine particles under high electric pulse current (between $10^4$ and $10^{ 6}$ $A/mm^2$) within a micro second time. To prevent full oxidations of Cu powder, the surface of powder has been slightly passivated with thin CuO layer. X-ray diffraction analysis has shown that pure Cu nanopowders were obtained at $N_2$ atmosphere. As the oxygen partial pressure increased in $N_2$ atmosphere, the gradual phase transformation occurred from Cu to $Cu_2$O and finally CuO nanopowders. The spherical Cu nanopowders had a uniform size distribution of about 100nm in diameter. The Cu-oxide nanopowders were less than 70nm with sphere-like shape and their mean particle size was 54nm. Smaller size of Cu-oxide nanopowders compared with that of the Cu nanopowders results from the secondary explosion of Cu nanopowders at oxygen atmosphere. Thin passivated oxygen layer on the Cu surface has been proved by XPS and HRPD.

• Particle and aerosol research
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• v.13 no.1
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• pp.25-31
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• 2017

This paper offer the characteristics for the detection and classification of biological and non-biological aerosol particles in the air by using laser-induced-fluorescence (LIF) based Bio-aerosol Detection System (BDS). The BDS is mainly consist of an optical chamber, in-outlet nozzle system, 405 nm diode laser, an avalanche photo detector (APD) for scattering signal and photomultiplier tubes (PMT) for fluorescence signals in two different wavelength range ; F1, 510-600 nm and F2, 435-470 nm. The detection characteristics, especially ratio of fluorescence signal intensity were examined using well-known components : polystylene latex (PSL), fluorescence PSL, $2{\mu}m$ of SiO2 micro sphere, dried yeast, NADH, ovalbumin, fungicide powder and standard dust. The results indicated that the 405 nm diode laser-based LIF instrument can be a useful bio-aerosol detection system for unexpected biological threaten alter in real-time to apply for dual-use technology in military and civilian fields.

• Journal of the Korean Ceramic Society
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• v.42 no.8 s.279
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• pp.537-541
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• 2005

Silicon nitride is one of the most successful engineering ceramics, owing to a favorable combination of properties, including high strength, high hardness, low thermal expansion coefficient, and high fracture toughness. However, the impact damage behavior of $Si_3N_4$ ceramics has not been widely characterized. In this study, sphere and explosive indentations were used to characterize the static and dynamic damage behavior of $Si_3N_4$ ceramics with different microstructures. Three grades of $Si_3N_4$ with different grain size and shape, fine-equiaxed, medium, and coarse-elongated, were prepared. In order to observe the subsurface damaged zone, a bonded-interface technique was adopted. Subsurface damage evolution of the specimens was then characterized extensively using optical and electron microscopy. It was found that the damage response depends strongly on the microstructure of the ceramics, particularly on the glassy grain boundary phase. In the case of static indentation, examination of subsurface damage revealed competition between brittle and ductile damage modes. In contrast to static indentation results, dynamic indentation induces a massive subsurface yield zone that contains severe micro-failures. In this study, it is suggested that the weak glassy grain boundary phase plays an important role in the resistance to dynamic fracture.

• Journal of the Korean association of regional geographers
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• v.9 no.3
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• pp.248-261
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• 2003

Through a qualitative analysis of the Ikuno Korean Festival in Osaka, this article examines and critiques how identities are constructed, and how this process is shaped by the mediation of intra and inter-community concerns. Particular attention is paid to the potential of reorganized culture through a thinking of similarity rather than difference. The dynamic interrelations suggest that festival provides a particular and informal public sphere wherein certain social logics and identities are contested. These discursive arenas are therefore marked by certain exclusions and inclusions. This study shows the complex process of identification at the micro-level through which identification is constituted and continuously negotiated.

• Journal of The Korean Digital Architecture Interior Association
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• v.7 no.2
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• pp.9-17
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• 2007

After 20th century, The using of data tend to important in a sphere of architecture. The recent European including MVRDV, Rem Koolhaas, Van Verkel and Zaha Hadid tend to the their own design strategy based on the objective data. This architectural design method leads to make new paradigm of contemporary architecture. For the purpose of the understanding a part of new architecture paradigm(datascping), I will analyze the relation of Thing system and Formation system in 36 works of MVRDV from 1992 to 2006. As a results are as follows. The purpose The results of this research are as follows: First, The physical and social elements(Thinking system) are density of site, networking, lighting & vista, micro-climate, energy, noise & vibration, life style, city, communication and variety. Second, The Formation system is layering & stacking, open & close, folding & extending and eco-friendly design. Finally, the major matrix of MVRDV's works is pragmatic and systematic approach to the lighting, climate and variety of community.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1118-1120
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• 2009

Micro-size CdS spheres of hollow shape were fabricated through the self-assembly of high density arrow-like nanorods. The synthesis of the CdS hollow spheres were accomplished in an aqueous solution of cadmium nitrate and triblock copolymer (Pluronic P123) at low temperature (80 ${^{\circ}C}$) through the slow release of S2- ions from thioacetamide. Morphology of the fabricated CdS hollow spheres was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The results indicate that the arrow-like CdS nanorods are simultaneously grown and attached each other to form the building units that become the spheres with hollow inside as a self-assembled process. The CdS spheres have a diameter of $2{\sim}3 {\mu}m$ and consist of the nanorods with a length of$\sim$800 nm. The nanocrystal building blocks have a hexagonal CdS structure.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.210.1-210.1
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• 2012

We report technique used for improved measurement uncertainties for Photon detection efficiency(PDE) of $1mm^2$ single pixel SiPM. It consists of 470nm LED light source, two 2-inch integrating sphere and two NIST calibrated silicon photodiodes that have ${\pm}2.4%$ calibration error. With raytracing simulation of our experimental setup, we predict number of photon into SiPM and measurement uncertainty. For MPPC, Hamamatsu suggested PDE(1600 micro pixel) including crosstalk and afterpulse is 23.5% at 470 nm. By using new low calibration error photodiode and raytracing simulation, our simulation result has ${\pm}3%$ measurement uncertainty. The technical detail of measurement, simulation are presented with the results and implication.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.3
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• pp.9-18
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• 1999

In this study, Metallugical properties between Sn-3.5Ag, Sn-37Pb eutectic solders and Au/Ni/cu substrate according to time span above the melting point were investigated. A conventional reflow soldering machine wert used for this study and time span above the melting point was determined by changing peak soldering temperature and conveyor speed. As results, scallop type intermetallic compounds of $Ni_3Sn_4$ were formed at joint interface and no Cu-Sn compounds were found at all; Ni layer performed as a barrier for Cu diffusion. As the peak soldering temperature increased, thickness of the intermetallic compound layer increased; maximum thickness of the scallop-layer was 2.2$\mu\textrm{m}$. The shape of scallops were transformed from hemi-sphere type to elliptical shape with smaller size. Micro-hardness of the solder joint decreased as the eutectic structure of Sn-3.5Ag and Sn-37Pb increased.

• The Korean Journal of Archival Studies
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• no.4
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• pp.131-161
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• 2001

This paper is to examine the bibliographical description of the revolutionary historical archives and the standardization of the archives management in China. The standardization in the field of records and archives management was not initiated on its own way but as a part of national - leveled standardization. As a first step National Committee on Technical Standardization of Literature was established, followed by the establishing of Committee on Technical Standardization of Micro - filming and Committee of Technical Standardization of Paper Form. The standardization of the records and archives management was carried out in the context of functions of these three committees. In 1983 the standardization in the sphere of records and archives management speeded up, when the National Archives Administration formed small organizations which led the standardization work all over the country. A committee of standardization originated from small organizations and it brought a great progress of the standardization. If some opinions on standardization were submitted from records offices or related offices, they were examined by the committee of standardization. The opinions that were submitted by the committee of standardization were examined by the National Archives Administration which proclaimed it officially. The Chinese government commenced to establish the bibliographical data centre for historical archives and materials on the basis of this process of standardization. In the case of the revolutionary historical archives the description was made on the level of sources(provenance), which was sent to the bibliographical data centre for historical archives and materials. The Chinese government set digitalizing as a goal in records and archives management in the middle of 1990's. It was regulated that the description of records item that should be transferred to the center must be digitalized. However, the description of the file level was not made separately being reflected in the process of description of item level. (The second part of the paper will be released in the next volume).