• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.583-588
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• 2015

Asymptotic method has been often used to theoretically analyze the complete contact problem. The error of the asymptotic results increases as the distance from the contact edge increases. The singularity cannot be properly obtained from a finite element (FE) analysis owing to the finiteness of the element size. In the present work, the complete contact problem in bonded condition is analyzed using a combined experimental-numerical approach to assist and/or compare with the asymptotic results. Al and Cu alloys are used for the material combination of the punch and substrate. 120 and 135 degrees are used for the punch angle. The FE models are validated by comparison of displacement distributions obtained by the FE analysis and $moir{\acute{e}}$ experiment. Generalized stress intensity factors are evaluated using the validated FE models. Stress field in the vicinity of the sharp contact edges obtained from the FE and asymptotic analyses are compared. The discrepancies are also discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.602-608
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• 2005

We have studied to obtain the SAW filter for the Single Phase Unidirectional Transduce. (SPUDT), was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we performed computer-simulated by simulator. We can fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulations. Also, we have performed to obtain the properly conditions about impedance matching of the SAW filter for SPUDT. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are 5000A and $3.6{\mu}m$, respectively. And the width of IDT' fingers is $2.4{\mu}m$, and the space between IDT' finger and reflector is $2.0{\mu}m$. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7.7MHz after when we have matched impedance. Also, we could obtain that ripple characteristics is less than 0.4dB and standing wave ratio is probably 1.5 after when we have matched impedance.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.147-163
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• 2000

The mineralogy and chemical composition of reddish to brownish yellow residual soils, so called "Hwangto" have been examined according to representative host rocks. The result of the study indicates that Hwangto consists of 40-80% clay minerals and various minerals such as quartz, feldspar, hornblende, goethite, and gibbsite. Clay minerals include kaolinite, halloysite, illite, hydroxy interlayered vermiculite (HIV), mica/vermiculite interstratifield mineral and chlorite. The mineralogical constituents and contents of Hwangto were different depending on the types of host rocks. Moreover, the Jurassic granitic rocks contain relatively more kaolin minerals, whereas the Cretaceous granitic rocks contain more HIV and illite. In addition, reddish Hwangto contains relatively more kaolinite and HIV, and yellowish Hwangto contains more illite and halloysite. It is suggested that feldspars and micas of host rocks were chemically weathered into illite, halloysite, illite/vermiculite interstratified minerals, and HIV, and finally into kaolinite. Compared with their host rocks, the major chemical compositions of Hwangto tend to contain more $Al_2O_3,\;Fe_2O_3,\;H_2O$ in amount and less Ca, Mg, and Na. Hwangto contains relatively high amount of trace elements, P, S, Zr, Sr, Ba, Rb, and Ce including considerable amount of Li, V, Cr, Zn, Co, Ni, Cu, Y, Nb, La, Nd, Pb, Th in excess of 10 ppm. Relatively high amount of most trace elements were detected in the Hwangto. The major and minor chemical compositions of the Hwangto were different depending on the types of host rocks. However, their difference was in the similar range compared with the compositions of host rocks.

• Resources Recycling
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• v.11 no.4
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• pp.11-16
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• 2002

Analysis and separation of constituent materials of old car have been performed by using the industrial shredding line. For this aim, three old cars made by domestic automobile manufacturers, Sonata II, Sephia and Prince were chosen and delivered in pressed form without engine, tires and doors, etc. Shredding line was substantially composed of pre- and main-shredder. cyclone, magnetic separation, eddy current separation and man-power separation. From the separation of shredder products, iron scrap was observed to be the major material of old car accounting for 60.1 ％ of total weight and non-ferrous metals involving Al, Cu and Zn, etc. were about 2％. Light fluff, about 90％ of total fluff product, was comprised with plastic, fiber and sponge, etc. and the fraction of 5 cm undersize in light fluff was 70.5%. In case of heavy fluff, however. rubber and plastic were found to be the major constituent materials of it. Among the constituent materials of fluff, plastic showed the highest calorific value, more than 10,000 cal/gr and leather and rubber showed relatively high chlorine content, 10.3 and 2.55 wt%, respectively.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1524-1526
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• 2002

본 논문에서는 $1.62{\times}1.0{\times}0.88mm^3$ 크기의 C-type과 $1.58{\times}0.82{\times}0.94mm^3$ 크기의 H-type RF 칩 인덕터를 제작하고 그들의 고주파 특성을 비교하였다. 본 연구에서는 저손실 $Al_2O_3$ 코아 물질과 직경 $40{\mu}m$의 구리(Cu) 코일을 사용하였다. 권선수를 $2{\sim}14$회로 하여 인덕턴스(L), 품질계수(Q), 임피던스의 크기와 위상, 커패시턴스(C)를 HP4291B Impedance/Material Analyzer로 측정하였다. 10회 권선시 C-type은 55nH, H-type은 67nH, 14회 권선시 C-type은 100nH, H-type은 122nH 정도로 측정되었다. 실험 결과 H-type이 C-type보다 동일 권선수에 대하여 높은 인덕턴스와 높은 자기공진주파수(SRF)를 나타냄을 확인하였다. 또한 최대 품질계수는 두 형태가 거의 비슷한 값($55{\sim}87$)을 가짐을 관찰하였다. 따라서 H-type이 C-type보다 우수한 성질을 나타냄을 알 수 있다.

• Journal of Korea Foundry Society
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• v.36 no.6
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• pp.202-207
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• 2016

The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the ${\alpha}$ phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nominal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of $703-781N/mm^2$, elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.

• The Korean Journal of Community Living Science
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• v.17 no.1
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• pp.79-86
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• 2006

This study purposes to find the best one for dyeing with artemisia in order to develop a more efficient method of dyeing with artemisia and investigates the antibiotic activities of artemisia. After dyeing cotton, rayon, silk, wool and nylon fabrics with dyebath extracted from artemisia, observation on dyeability by temperature, concentration and time has been carried out. And I took an observation on color change, color fastness to washing and color fastness to light after mordanting treatment. Also observation on the antibiotic properties of non-dyed fabrics, artemisia-dyed fabrics and artemisia-dyed fabrics with post-mordant has been performed to investigate the antibiotic activities of artemisia. And the following results have been obtained. 1. The dyeability of artemisia was better for protein fabrics such as silk or woo and amide-based synthetic fabrics like nylon than for cellulose fabrics such as cotton and rayon. 2. For all tested fabrics, the dyeability was increased as the concentration of artemisia dyebath, dyeing time and dyeing temperature was increased. Especially the dye ability for protein fabrics was most affected by the temperature, and high dyeability was obtained at high temperatures. 3. For the color fastness of artemisia-dyed fabrics with mordanting treatment, the color fastness to washing was good with grade of 4-5 while the color fastness to light ranged from grade 2 to grade 3, which requires improvement for practical use. 4. The artemisia-dyed fabrics were shown to have much higher antibiosis than the non-dyed fabrics, and the artemisia-dyed fabrics with mortanting treatment showed the following result; Cu 99.9%, Al 64% and bittern 64.7%.

• Economic and Environmental Geology
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• v.12 no.2
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• pp.79-93
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• 1979

Twenty five samples of the scheelite-powellite series from twelve Korean tungsten deposits of various geologic settings were studied mineralogically and geochemically. Variations in the trace-element contents of the scheelite minerals are considered in relation to geologic settings and mineralogic properties. Scheelites from ore deposits developed in similar geologic settings and under similar physicochemical conditions are characterized by specific combinations of trace elements.

• Textile Coloration and Finishing
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• v.22 no.3
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• pp.194-206
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• 2010

This study was carried out to identify the optimum dyeing conditions for maximum dye uptake of Prunus yedoensis Matsumura flower extract on silk fabric and to investigate hue/tone characteristics and fastness properties of the dyed fabrics. As results, the flower extract was found to contain flavonoids by FT-IR and to show yellowish shade by UV-vis spectrum. Silk fabric was optimized for maximum dye uptake to five repetitions of dyeing at $80^{\circ}C$ for 60 min with an extract concentration of 600% owf in terms of both K/S and color differences. Pre-mordanting was more effective to dye uptake than post-mordanting for all of the mordants used. Un-mordanted and pre-mordanted fabric showed YR(Yellow Red) while most of post-mordanted ones did Y(Yellow). Main tones of dyed fabrics were sf(soft) and lt(light) in the case of unmordanting or Al-mordanting whereas they were d(dull) and g(grayish) by post-mordanting with Cu, Cr, and Fe, respectively. The fastness grades to rub and dry cleaning were reasonably good for most dyeing conditions while those to light were poor. Finally dyeing condition for each hue/tone of the dyed silk with the flower extract was optimized considering fastness properties.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.718-726
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• 2007

There are many varieties of asbestos: chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophylite. These are widely used in construction materials, brake lining, textile, and so on. Even though non-asbestos fibers such as glassfiber and rockwool have manufactured because asbestos causes asbestosis, lung cancer, mesothelioma, etc., some bad effects of non-asbestos have been also reported. PCM (phase contrast microscopy) and PLM (polarized light microscopy) have been used to qualitatively analyze asbestoses. These techniques have serious drawbacks when identifying and separating various asbestoses. Recently scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX) has been known as an useful tool to analyze airborne particle since it provides physical and chemical information simultaneously. The purpose of the study was to classify both asbestos and non-asbestos fibers and finally to develop their source profiles by using the SEM/EDX. The source profiles characterized by 6 different types of asbestos fibers and 2 types of non-asbestos fibers had been developed by analyzing a total of 380 fibers. Analytical parameters used in this study were length, width, aspect ratio, and shape as physical information, and Na, Mg, Al, Si, K, Ca, Cr, Mn, Fe, and Cu as chemical information. All the parameters were intensively reviewed.