• Journal of the Korea Institute of Building Construction
• /
• v.24 no.2
• /
• pp.169-180
• /
• 2024

In this study, to suggest an efficient method of using coal gasification slag(CGS), a byproduct from integrated gasification combined cycle(IGCC), as a combined fine aggregate for concrete mixture, the diverse performances of concrete mixtures with combined fine aggregates of CGS, river sand, and crushed sand were evaluated. Additionally, using CGS, the reduction of the hydration heat and the strength developing performance were analyzed to provide a method for reducing the heat of hydration of mass concrete by using combined fine aggregate with CGS and replacing fly ash with cement. The results of the study can be summarized as follows: as a method of recycling CGS from IGCC as concrete fine aggregate, a combination of CGS with crushed sand offers advantages for the concrete mixture. Additionally, when the CGS combined aggregate is used with low-heat-mix designed concrete with fly ash, it has the synergistic effect of reducing the hydration heat of mass concrete compared to the low-heat-designed concrete mixture currently in wide use.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.6
• /
• pp.1047-1052
• /
• 2001

The pigment content in meju fermented by a Monascus species with different materials was studied. The relations between growth of M. pilosus and pigment production were positive and the correlation coefficient associated with this relationship was determined to be : r = 0.9879. Pigments produced by M. purpureus and M. pilosus were composed of 9 and 8 bands, respectively. One kind of them was yellowish, whereas the others were reddish. Total pigment levels in rice meju fermented by M. purpureus and M. pilosus were 335.25 and 1428.90$\mu\textrm{g}$/g, respectively. Pigment levels in the mejus fermented at 3$0^{\circ}C$ showed higher than those at 20 and 4$0^{\circ}C$. The order of pigment content in meju was polished rice > germinated brown rice > wheat > brown rice > waxy brown rice > germinated waxy brown rice. Pigment production by M. pilosus was higher than that of M. purpureus. Pigment content in rice meju prepared by adding 10% seed culture was highest, and pigment content of granulated rice was higher than that of powdered rice. Pigment production was not desirable in soybean meju fermented by seed culture, whereas the pigment levels in meju by adding 10% powdered rice and 10% powdered rice seed meju increased by 23.0 ~75.0 $\mu\textrm{g}$/g.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.5 no.2
• /
• pp.56-64
• /
• 2006

Rapid progress in many branches of technology has led to a demand on new materials such as high strength light weight alloys, powdered alloys and composite materials. The hydrostatic extrusion is essentially a method of extruding a clad rod through a die. In order to investigate the effect of the process conditions such as friction heat, deformation and clad thickness on the clad extrusion process, viscoplastic finite element simulations were conducted. A specific model for theoretical analysis used in this study is The single scalar variable version of Hart's model. An experiment also has been carried out using 1.5MN hydrostatic extruder with variable speed ram, LVDT and load cell for comparison. It is found that the hydrostatic extrusion pressure considering the effect of heat dissipation in this theoretical work was closer to the experimental pressure than the isothermal hydrostatic extrusion pressure.

• Korean Journal of Computational Design and Engineering
• /
• v.8 no.3
• /
• pp.150-156
• /
• 2003

Direct Metal Deposition (DMD) is a new additive process producing three-dimensional metal components or tools directly from CAD data, which aims to take mold making and metalworking in an entirely new direction. It is the blending of five common technologies: lasers, CAD, CAM, sensors and materials. In the resulting process, alternatively called laser cladding, an industrial laser is used to locally heat a spot on a tool-steel work piece or platform, forming a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the metal pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is eventually built line-by-line, one layer at a time. DMD produces improved material properties in less time and at a lower cost than is possible with traditional fabrication technologies.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.802-803
• /
• 2006

Recently, there has been a growing demand for soft magnetic materials with high conversion characteristics, due to the trend of electric devices to higher-frequency range. For ruduceing core loss in the high-frequency range, using finely grained and high-resistivity Fe-based alloy powder is most efficient methods. But, conventionally, there's been a compressibility problem for such powder. In this work, Fe-based alloy powder that offers both high resistivity and high compressibility was developed by studyuing composition of the powder, and reduction of core loss of P/M soft magnetic materials in the high frequency range was achieved.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.4
• /
• pp.845-849
• /
• 1999

We can make Samul Chol Pyon to add four powdered Korean medicines to Chol Pyon. The purpose of this study is to present the standard recipe of Samul Chol-Pyon for the taste of the moderns, taking the tests of physical charcateristics, sensory qualities. The white Chol Pyon and the group of 5% raw materials for Samul tang are comparatively good for color, odor, taste, softness, chewiness and overall quallity with other group of raw materials. To add Korean medicine browns the Samul Chol Pyon much deeper. The changes in textural properties of Chol pyon during storage at 20$\pm$5oC were measured using a rheometer for hardness, fractureability, adhesiveness, resilience, and cohesiveness. The hardness, fractureability and adhesiveness were increased with the additon of in Samul tang raw material powder. The cohesiveness and chewiness were increased by adding Samul tang powder in the course of time. The Chol Pyon prepared with 5% of Samul tang powder showed the superior sensory qualities as Samul Chol Pyon.

• Korean Journal of Materials Research
• /
• v.20 no.4
• /
• pp.204-209
• /
• 2010

Recent high efficiency electronic devices have been found to have heat emission problems. As for LEDs, an excessive increase in the device temperature causes a drop of the luminous efficiency and circuit lifetime. Therefore, heat release in the limited space of such electronic parts is very important. This is a study of the possibility of using a coating of carbon materials as a solution for the thermal emission problem of electronic devices. Powdered carbon materials, cokes, carbon blacks, amorphous graphite, and natural flakes were coated with an organic binder on an aluminum sheet and the subsequent thermal emissivity was measured with an FT-IR spectrometer and was found to be in the range of $5{\sim}20\;{\mu}m$ at $50^{\circ}C$. The emissivity of the carbon materials coated on the aluminum sheet was shown to be over 0.8 and varied according to carbon type. The maximum thermal emissivity on the carbon black coated-aluminum surface was shown to be 0.877. The emissivity of the anodized aluminum sheets that were used as heat releasing materials of the electronic parts was reported to be in the range of 0.7~0.8. Therefore, the use of a coating of carbon material can be a potential solution that facillitates heat dissipation for electronic parts.

• Journal of the Korean institute of surface engineering
• /
• v.42 no.5
• /
• pp.191-196
• /
• 2009

Nanocrystalline Cu thin films were electrodeposited from sulfate baths and investigated systematically the influences of $Cu^{2+}$ concentration and additives on current efficiency, residual stress, surface morphology, and XRD patterns of electrodeposited Cu film. Current efficiency was nearly 100% at from 0.2M to 1.0 M $Cu^{2+}$ concentration. but it was linearly increased with $Cu^{2+}$ concentration at less than 0.2M. The residual stress was observed in range of 7.9 to 18.4 MPa and tensile stress mode. Dendritic and powdered form was obtained at below 0.1 M. As increased with $Cu^{2+}$ concentration in solution, the main peak in the XRD pattern shifted (111) and (220) from (200). In the other hand, all about 100% current efficiency observed in all additive concentration systems, and residual stress observed in range of 20.4 to 26.3 MPa tensile stress. The condition 5(Ultra make-up - 10 ml/l, Ulta A - 0.5ml/l, Ultr B - 0.5 ml/l) was good surface morphology, and fcc(111) peak in XRD patterns increased with increasing additive concentration.

• Korean Journal of Materials Research
• /
• v.29 no.6
• /
• pp.363-370
• /
• 2019

The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

• Journal of Ceramic Processing Research
• /
• v.19 no.6
• /
• pp.483-491
• /
• 2018

Effects of additives on phase development and physico-mechanical properties of mullite-carbon was investigated. Powdered clay, kaolinite and graphite of predetermined compositions were blended with additives using ball mill for 3 hrs at 60 rev/min. Samples were produced by uniaxial compression and sintered between $1400^{\circ}C$ and $1600^{\circ}C$ for one hr. They were characterized for various properties, developed phases and microstructural features. It was observed that the properties and phase developments in the samples were influenced by the additives. 10 wt % SiC served as nucleating point for SiC around $1400^{\circ}C$. 10wt % $TiO_2$ lead to development of 2.5 wt % TiC at $1500^{\circ}C$ which increased to 6.8 wt % at $1600^{\circ}C$. Ifon clay in the sample leads to development of anorthite and microcline in the samples. 10wt % $TiO_2$ is effective as anti-oxidant for graphite up to $1500^{\circ}C$. Base on strength and absorbed energy, sample C (with 10wt % $TiO_2$) sintered at $1500^{\circ}C$ is considered to be optimum.