• Archives of Plastic Surgery
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• v.33 no.5
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• pp.587-591
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• 2006

Purpose: Since Rheinwald and Green laid the foundation of epidermal cell culture technology in 1975, many clinicians and scientists have attempted to prove the effectiveness of cultured epidermal autologous(CEA) or homogenetic(CEH) grafts in the wound healing process. In contrast to CEA which cultured from a patient's skin on demand, Cultured Epidermal Homograft(CEH) can be readily available to use on cleaned wounds. In this study, we conducted a controlled clinical trial in order to confirm the effectiveness of CEH in treating partial-thickness 2nd degree burn wounds. Methods: From July 2003 to January 2004 at Hangang Sacred Heart Hospital, we performed a clinical trial in which 35 patients who suffered from 2nd degree burns were enrolled. Wounds were randomly divided into two parts, control and test sites. Test sites were treated with allogeneic keratinocyte sheets ($Kaloderm^{(R)}$, Tegoscience Inc.), a CEH commercialized in Korea. Results: All wounds healed completely without any major complication. The complete healing took $8.3{\pm}2.8$($mean{\pm}S.D.$) days in the test sites as opposed to $11.7{\pm}3.3days$ in the control sites. Conclusion: Based on these results, we concluded that CEH accelerates re-epithelialization of partial thickness burn wounds and CEH can be an safe alternative to skin grafts for 2nd degree burns.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.4
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• pp.401-411
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• 2015

This study was performed to investigate the wound healing effect of skin regeneration cosmetics utilizing low molecular weight Polydeoxynucleotide (PDRN). High purity PDRN was prepared from salmon testes poly-deoxy-ribonucleotide through protein and toxin removal process and molecular weight reduction. In order to evaluate the wound healing effect of PDRN in SD rats, 4 sites of dorsal skin of each animal were excised by using biopsy punch and $500{\mu}L$ of test solution was topically applied once daily for 4 weeks. The tissue changes were observed for every week during the application periods. After applying the PDRN to the wound, the skin was cut flower and contraction of the wounds more quickly, and the coating of PDRN in the wound area was reduced significantly as compared to the positive control group $Fucidin^{(R)}$ applied. The microscopic observation of stained tissue showed that a positive control was most rapid in re-epithelialization ability followed by the PH group, PDRN group, HA group. In addition, transforming growth factor ($TGF-{\beta}$) and vascular endothelial growth factor (VEGF), such as in the growth factor was similar to the results of staining of tissue lesions. In conclusion, it is determined that the low molecular weight PDRN has the therapeutic effect to the wound, and could be used as a functional material of cosmetics and medical industries.

• Corrosion Science and Technology
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• v.5 no.2
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• pp.52-61
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• 2006

Recently, much of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as $WC-Ti_{0.6}Al_{0.4}N$, $WC-Ti_{0.53}Al_{0.47}N$, $WC-Ti_{0.5}Al_{0.5}N$ and $WC-Ti_{0.43}Al_{0.57}N$. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball ($H_R=66$) having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Results have showed an improved wear resistance of the $WC-Ti_{1-x}Al_xN$ coatings with increasing of Al concentration. $WC-Ti_{0.43}Al_{0.57}N$ coating with the lower surface roughness and porosity with good adhesion enhanced wear resistance.

• Architectural research
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• v.12 no.1
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• pp.49-55
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• 2010

Stone powder sludge is a by-product of the manufacturing process of crushed sand. Most of it is dumped with soil in landfills, and the disposal of stone powder sludge causes a major environmental problem. This paper investigates the applicability of stone powder sludge in fly ashbased geopolymer. For this, stone powder sludge was used to replace fly ash at a replacement ratio of 50% and 100% by weight. The compressive strength of the samples was measured and scanning electron microscopy/ energy dispersive spectroscopy (SEM/EDS) analysis and X-ray diffraction (XRD) were performed. The test results indicated that the optimum level of the alkali activator ratio ($Na_2SiO_3$/NaOH) for fly ash-based geopolymer using stone powder sludge was 1.5. The strength development is closely related to the NaOH solution concentration. In addition, the compressive strength of the sample cured at $25^{\circ}C$ was significantly improved between 7 days and 28 days, even though the strength of the sample showed the lowest value at 7 days. Microscopy results indicated that a higher proportion of unreacted fly ash spheres remained in the sample with 5M NaOH, and some pores on the surface of the sample were observed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.8-13
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• 2015

Recently, Illumination industry of LED module has been focused to industry technology for energy conservation of nation. The LED device is excellent to power efficiency due to semiconductor light source element. And the application to the lighting circuit technology can be designed to the sensitive lighting system for human sensitivity control. In this paper, as a process for analyzing the operating temperature of standardized electronic device including LED device has analyzed about fusing character with in designed micro fuse for electronic device protection from the over current. Using the de-rating technique, which is performed to micro fuse fusing test in the range of $-30^{\circ}C{\sim}120^{\circ}C$ thermostatic chamber. To the output data in each temperature zone, it is performed to first-order linear fitting. Additionally, applying the resistance temperature coefficient and statistical data for the reliable analysis has derived to the metal element resistance of micro fuse with temperature change of the thermostatic chamber. As a research result, The changed temperature effect of thermostatic chamber was confirmed regarding fusing time change.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.118-130
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• 2015

Fine dust containing iron compounds is of current interests in metro subway as well as large scale industries including iron manufacturing and smelting works. This work attempts to find a new design of magnetic filter module for iron dust capture. It simulated the vertical rectangular duct with metal mesh which might promote electric fields in the duct space. A lab test using coal fly ash composed of 8.66% Fe with the most form of $Fe_3O_4$ and $Fe_2O_3$ showed capability of magnetic collection. It showed the capture efficiency with 80~93% for $PM_{2.5}$ depending on magnetic intensity. Ferromagnetic wire mesh contributed up to 50% of collection increment.

• Journal of Welding and Joining
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• v.29 no.1
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• pp.59-64
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• 2011

Al6082-T6 is widely used because of its corrosion resistance and excellent strength. HAZ softening occurs in MIG welding process for this aluminium alloys because this aluminium alloy is heated to higher temperature than its aging temperature during welding. Therefore, low heat input and minimum standard deviation of heat input are required for narrow HAZ width and, for higher strength of welds. In this study, Al6082-T6 was used to examine for HAZ softening with various heat input in aluminium MIG welding. For weldments, micro hardness was measured and tensile test was carried out. Minimum hardness was increased at high speed welding such as 80cm/min and 120cm/min in welding speed comparing with 40cm/min. Also, in case of high speed welding such as 80cm/min and 120cm/min, tensile strength of weldments was increased about 10% comparing with low speed welding(40cm/min).

• Journal of Ocean Engineering and Technology
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• v.4 no.2
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• pp.100-111
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• 1990

In this paper, fatigue tests were carried out at stress test levels of 461 MPa, 441 MPa, and 431 MPa by using smooth specimen of$2_{1/4}$ Cr-1 Mo steel with the stress ratio(R) of 0.05. The initiation, growth and coalescense process of the major cracks and sub-cracks among the fatigue cracks on the smooth specimen are investigated and measured under each stress level at a constant cycle ratio by the replica technique with optical microscope. Some of the important results are as follows: In spite of the difference of stress levels, the major crack data gather into a small band in the curve of surface crack length and crack depth against cycle ratio N/Nf. The sub-crack data, however, deviate from the band of the major crack. The growth rates, da/dN, of major and sub-crack plotted against the stress intensity factor range, ${\Delta}K$, have the tendency to be compressed on a relatively small band. But it is more effective to predict fatigue life through major cracks. The propagation behavior of surface microcracks on the smooth specimens coincides with that of the specimen having an artificial small surface defect or through crack.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1881-1883
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• 2002

Recently, 345kV XLPE Cable and Accessories have been developed and will be applied for Youngseo$\sim$Youngdeungpo project in Korea. So, let this project and the process of development introduce on this paper. The cable type and length of this project is 345kv XLPE 1C*$2000mm^2$ 66km and all cable will be pulled on cable tunnel. The diameter of cable insulation was designed as 27mm, we could reduce it by appling for hi-tech and super-clean system. Joints were developed by a pre-fabricated type which considered high safety and economic issues. We had also done Pre-Qualification test for verifying the reliance of cable and accessories before construction. As we developed this 345kV XLPE cable system including its accessories at the same time, we can have higher technologies and contribute safe power in transmission lines. In adtionally, we can have a stable status for suppling EHV cable systems to a variety foreign customers by ourselves.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.13-18
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• 2007

The mother Ni-W (1-5 wt.%) alloy billets for coated conductor substrate were fabricated by powder metallurgy process. The tensile test results for the sintered Ni-W rods showed the increase of mechanical strength and decrease of ductility with increasing W content due to the solid solution hardening. All the fracture surfaces of the tested specimens showed the typical ductile fracture mode of dimple rupture due to the local necking. The Ni-W alloy billets were made into tape by cold rolling. After the appropriate heat treatment for recrystallization, the brass texture formed by the cold rolling was converted to the complete cube texture. The in-plane and out of plane texture of the tapes estimated by x-ray pole figure were smaller than 9 degree and 7 degree, respectively. The effect of the W addition on the texture development seems not to be significant.