• Journal of Environmental Health Sciences
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• v.35 no.3
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• pp.226-234
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• 2009

The main objective of this study was to evaluate the effects on shape and size, compressive strength, water absorption and heavy metals leaching with various weight mixing ratios in waste ash brick products using waste recycling MSWI(Municipal Solid Waste Incinerator) bottom ash, steel slag and waste building material. The manufacturing processes for the waste ash brick consist of screening, mixing, conveyor transmission, compaction.forming, and curing steps of raw materials. The weight mixing ratios of steel slag around bottom ash were adjusted within the ranges of 10% to 30%. The reported results show that the width and thickness of the manufactured waste ash brick could be satisfied with $90{\pm}2mm\;and\;57{\pm}2mm$, respectively which are K.S. standards of products qualities. And in case of length, only 20-Ba50Ss30, 20-Ba60Wb20 and 20-Ba50Wb30 for the mixing ratios could be satisfied with $190{\pm}2mm$ that is K.S. standards of products quality. The compressive strength and water absorption for 20-Ba50Ss30 and 20-Ba70Wb10 were over $8N/mm^2$ and below 15% respectively that are K.S. standards of manufactured waste ash brick. The results of tests for the heavy metals leaching in the all manufactured waste ash bricks are also passed to the wastes management regulations. The cost analysis of 20-Ba50Ss30 is evaluated. The manufacturing cost is evaluated 34.3 won/brick with 8 hours and 20tons of raw material per day. Incinerators with problems in bottom ash disposal can therefore derive significant benefits from the application of waste ash brick production.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.31-37
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• 2015

A laser line welder using a solid-state laser (Yb:YAG) has been manufactured for joining ultra-thin cold-rolled steel coils in steelworks. The coils to be welded primarily range from 0.15 to 0.3 mm in thickness and 800 to 1,100 mm in width. Because the steel plate is extremely thin, it is very important to control the stop positions of the clamp at cutting and welding points. In this study, both hydraulic proportional control valves and LVDT sensor embedded cylinders were used to precisely control and monitor the positions of clamps with complementary stoppers. As a result, the positions could be controlled within an error of ${\pm}30{\mu}m$. Erichsen cupping tests on the welded joints show that the Erichsen index ranges from 4.4 to 4.6 mm. Furthermore, the tensile strength of welding points is comparable to that of the base metal.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.568-569
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• 2006

The use of the nickel free, high nitrogen stainless steel powder and nitriding during sintering of iron based materials have been shown as an alternative way to the conventional PM stainless steels containing nickel. Nitrogen as an alloying element for iron improves in an effective way the properties of sintered alloyed steels. The powder metallurgy route is a suitable way to introduce nitrogen into these alloys and, in particular, to produce high nitrogen (close to the solubility limit) stainless steels. The paper presents and discusses the nitriding behavior of nickel-free stainless steels produced by powder metallurgy method. Alloyed melt was atomized by nitrogen and in this way nitrogen was introduced into the powder. Further nitriding occurred during sintering in a nitrogen atmosphere. For comparison, compacts having the same composition as an alloyed powder were produced from elemental powders mixture. Sintering-nitriding behaviour of investigated materials has been controlled by dilatometry, chemical and X-Ray phase analysis and metallography. Mechanical properties of sintered compacts were also measured.

• Journal of Powder Materials
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• v.9 no.5
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• pp.303-306
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• 2002

P/M high speed steels with various Co contents were fabricated by gas atomization and Canning/HIP process. As Co content in P/M high speed steel increased, hardness, transverse rupture strength and yield strength in compressive testing increased due to solid solution hardening of Co in matrix. Especially, PM high speed steels with Co have high deformation resistance to repeated compressive loading.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.611-633
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• 1995

The pupose of this study was to compare the fracture strength of five kinds of all-ceramic crowns(Vintage, Dicor Empress-staining, Empress-layering, In-Ceram) luted with glass ionomer cerment and composite resin cement and to evaluate the effect of cements on the fracture stregth of all ceramic crowns. Five groups of twelve uniform sized all-ceramic crown specimens were fabricated. Six specimens of each group were cemented with glass ionomer cement(Fuji G.I. Cement) and the remaining six specimens of each group were etched, silane-treated, and cemented with composite resin cement(Bistite resin cement). The crowns were stored in water$(37^{\circ}C)$ for 1 day prior to loading in an Instron, using a steel ball(diameter 4mm) at a crosshead speed of 0.5mm/min. The crowns were angled $30^{\circ}$, so the steel ball contacted with the crowns 2mm lingual from the mid-incisal edge. The results obtained were summarized as follows ; 1. With G.I. cement, mean fracture load(Kg) Were : Intage : $18.33{\pm}1.47$ ; Empress-staining : $23.92{\pm}6.67$ ; Dicor : $24.0{\pm}5.81$ ; Empress-layering : $26.92{\pm}2.80$ ; In-Ceram : $51.58{\pm}6.87$ ; ANOVA revealed a significant difference existed(p<0.05) between the group A(Vintage, Dicor, Empress-staining, Empress-layering) and group B(In-Ceram). 2. With Resin cement, mean fracture load(Kg) were : Intage : $22.75{\pm}4.97$ ; Dicor : $42.75{\pm}7.07$ ; Empress-staining : $44.08{\pm}7.99$ ; Empresslayering : $50.42{\pm}5.43$ ; In-Ceram : $52.58{\pm}6.51$ ; ANOVA revealed a significatnt difference existed(p<0.05) between the group A(Vintage) and B(Dicor, Empress-staining Empress-alyering, In-Ceram). 3. Resin cement significantly increased the fracture strength of the all-ceramic crowns for Dicor(156%), Empress-staining(185%), Empress-alyering(187%)(p<0.05); but did not increase the fracture strength of Vintage(128%) and In-Ceram(101%)(p>0.05). 4. Majority of the all-ceramic crowns show a wedge fracture extending through proximal surfaces to an apex, usually apical third(with G.I. cement) or middle third(with Resin cement) of the facial surface.

• Food Science of Animal Resources
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• v.32 no.2
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• pp.204-211
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• 2012

Although Arcobacter butzleri is a foodborne emerging pathogen causing gastroenteritis in human and animals, there are a few researches on the physical and chemical control methods. The aim of this study was to investigate the effect of ultraviolet radiation or ethanol treatment on A. butzleri. To demonstrate the UV effect, 8 ${\log}_{10}CFU$/mL of A. butzleri were spiked on stainless steel and the pork was then exposed to 250 nm of ultraviolet light for 108-648 mWs/$cm^2$. To ascertain the effect of ethanol, A. butzleri and A. butzleri spiked pork were soaked or sprayed 10, 35 and 70% of ethanol for 10 to 30 min. A. butzleri significantly decreased all of the UV doses in stainless steel, whereas, the reduction was just $0.92{\pm}0.62-1.29{\pm}0.34\;{\log}_{10}CFU$/mL in pork spiked with A. butzleri. In the ethanol groups, A. butzleri decreased significantly in 35% or 70% of ethanol in contrast, the bacterial counts were dropped slightly in A. butzleri spiked pork groups. Therefore, it is necessary to develop various kinds of control methods or hurdle technology for A. butzleri.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2719-2726
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• 2010

The purpose of this study was to investigate the scientific basic grounds for the assessment of health and environmental diseases resulting from air pollutants in Pohang. For this study, we investigated pollutants, weather characteristics and concentration distribution of fine particles ($PM_10$) yearly and each season, using data from Air Quality Monitoring Stations. The properties of concentration distribution and seasonal fluctuation of $PM_10$ were studied qualitatively and quantitatively using CALPUFF, air dispersion model. The average concentration of $PM_10$ for each season was spring($75.7{\mu}g/m^3$)>summer($56.8{\mu}g/m^3$)>winter($53.6{\mu}g/m^3$)>fall( $52.7{\mu}g/m^3$). In the case of spring, high concentrations appear due to the Asian dust frequently occurring. The contributions of $PM_10$ classified by the types of pollution source in Pohang were point source 62%>mobile source 33%>area source 5%. An important point is that 97% of emissions were produced from the iron manufacture in steel industry. Therefore, it is necessary to control the emission sources of pollutants and to construct an observation system at Pohang steel industrial complex from now on. It’s time to control the risk factors for health and environmental disease to protect the health of resident in Pohang and its neighboring areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1467-1473
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• 2013

In construction project, it is important to exchange and share the digital information generated by their own professional softwares. So this paper analyzed the information delivery requirements of steel structure according the structural design stages using IDM methodology. For schematic design stage and detailed design stage, the structural design information to share in each design stages is abstracted by defining the PM, ER, and FP. The new ERs and FPs are proposed by defining the new property sets(Psets), suchlike bolt gauge line, weld, scallop, and cope, to complement the structural design information of $IFC2{\times}3$. Finally, the reasonability of the proposed new ERs, FPs are verified by applying them to represent the standard steel connection sample in detailed design stage. As a result, the structural design information of standard steel connection could be stored and managed sufficiently by using the proposed new ERs and FPs.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.257-263
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• 2015

PURPOSE. In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. MATERIALS AND METHODS. Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. RESULTS. According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, $24.47{\pm}5.82{\mu}m$ before and $35.11{\pm}6.52{\mu}m$ after cementation; in the laser-sintered Co-Cr structure, it was, on average, $60.45{\pm}8.87{\mu}m$ before and $69.33{\pm}9.03{\mu}m$ after cementation. A highly significant difference (P<.001) was found in marginal gap measurements of galvano copings and a significant difference (P<.05) was found in marginal gap measurements of the laser-sintered Co-Cr copings. According to the SEM examination, surface properties of laser sintered Co-Cr copings showed rougher structure than galvano copings. The galvano copings showed a very smooth surface. CONCLUSION. Marginal gaps values of both groups before and after cementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings.

• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.115-120
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• 2014

PURPOSE. The aim of this in vitro study was to evaluate the effect of aging on the tear strength and cytotoxicity of four soft denture lining materials. MATERIALS AND METHODS. Four commonly used soft denture lining materials, (Coe-Comfort$^{TM}$ GC America Inc., Alsip, IL, USA; Coe-SOFT$^{TM}$ GC America Inc., Alsip, IL, USA; Visco-gel Dentsply Caulk Milford, DE, USA; and Sofreliner Tough M Tokuyama Dental Corporation Tokyo, Japan) were selected. Sixty trouser-leg designed specimens per lining material were fabricated using a stainless steel mold for tear strength testing. The specimens were divided into non-thermocycling and 1000-, and 3000-thermocycling groups. For the cytotoxicity test, twenty-four disk shaped specimens per material were fabricated using a stainless steel mold. The specimens were soaked in normal saline solution for 24 h, 48 h and 72 h. Cytotoxicity was measured by XTT assay in L929 mouse fibroblasts. Data were analyzed by two way analysis of variance and Dunnett's test (P<.05). RESULTS. Before thermocycling, Sofreliner Tough M ($10.36{\pm}1.00N$) had the highest tear strength value while Coe-Comfort$^{TM}$ ($0.46{\pm}0.10N$) had the lowest. After 3000 cycles, Sofreliner Tough M ($9.65{\pm}1.66N$) presented the highest value and Coe-Comfort$^{TM}$ ($0.42{\pm}0.08N$) the lowest. Sofreliner Tough M, in all incubation periods was the least toxic with significant differences compared to all other materials (P<.05). Coe-Comfort$^{TM}$, Coe-$SOFT^{TM}$, and Sofreliner Tough M did not show any significant differences within their material group for all incubation periods. CONCLUSION. This in vitro study revealed that aging can affect both the tear strength and cytotoxicity of soft denture materials depending on the composition.