• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.749-754
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• 1988

The texture measurement of Chinese cabbage leaves used for Kimchi preparation were con ducted by cutting and compression test and the results were compared to the sensory evaluation. The cutting force of cabbage leaf stalk increased by blanching or salting, and a maximum cutting force was attained by salting in 15% salt solution for 5 hours. The compression force and recovered height measured by compression test of Chinese cabbage leaf stalk decreased by blanching or salting, and the breaking point disappeared. Treatment with $CaCl_2$ solution increased the cutting force compression force and breaking strength of fresh leaves, but the effect disappeared by salting or blanching. Cutting strength could be used as a parameter indicating the hardness and chewiness of salted cabbage. Compression force and breaking strength could indicate the textural changes of blanched leaves, but were not useful for the measurement of hardness and chewiness of salted leave.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.259-264
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• 2016

In this study, we applied six different norbornene dialkyl esters as a plasticizer to an isoprene rubber (IR) and evaluated replaceability of DEHP which is an endocrine disruptor. IR test sheets were prepared by blending IR, norbornene dialkyl ester, vulcanizing agent, etc. and processing properties of the IR were evaluated by measuring Toque, scorch time, cure time and mooney viscosity. Mechanical properties of IR test sheet including hardness, tensile strength, 100% modulus and elongation were also measured and the physical properties of norbornene dialkyl ester applied as a plasticizer were compared to those using DEHN. Both the maximum and minimum toque for the norbornene dialkyl ester as a plasticizer were similar to those of using DEHP. In addition, the scorch and cure time of the former were slightly longer than those of the latter. The mooney viscosity for the case of DEHN was slightly lower than that of the latter. DEHN was also superior to DEHP in terms of processing. The hardness and thermal properties of all IR test sheets were measured to be similar to each other. The linear alkyl chain of norbornene compounds also exhibited good tensile characteristics.

• Journal of Powder Materials
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• v.11 no.5
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• pp.412-420
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• 2004

The purpose of the present study is to determine an optimum composition using cheaper powders keeping with high performance of hard rock cutting diamond saw blade. With 50Fe-20(Cu . Sn)-30Co specimen, a part of Co was replaced by Ni(5%, 10%, and 15%, respectively). These specimens were hot pressed and sintered for predetermined time at various temperature. Sintering is performed by two different methods of temperature controlled method and specimen dimension controlled method. In order to determine the property of the sintered diamond saw blade, 3 point bending tester, X-ray diffractometer, and SEM were used. As the Co in the bond alloy was replaced by Ni, the hardness of the specimen increased. Thus the 50Fe-20(CuㆍSn)-15Co-15Ni specimen showed the maximum hardness of 104(HRB). The results of 3 point bending test showed that flexure strength decreased along with increase in Ni content. This is attributed to the formation of intermetallic compound(Ni$_{x}$Sn) determined by X-ray diffraction. The fracture surface after 3 point bending test showed that diamond was fractured in the specimen containing 0%, 5%, and 10%Ni, and the fracture occurred at the interface between diamond and matrix in the specimen containing 15%Ni. The cutting ability test showed that the abrasive property was not changed in the specimen containing 0%, 5%, and 10%Ni. The optimum composition determined in this study is 50Fe-20(CuㆍSn)-20Co-10Ni.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.191-195
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• 2012

Heavy flint optical glass(SF57HHT) is new material that has extremely high transmittance. Due to brittleness and high hardness, optical glass is one of the most difficult to materials for ultra-precision turning. According to the hypothesis of ductile machining, all materials, regardless of their hardness and brittleness, will undergo transition from brittle to ductile machining region below critical undefromed chip thickness. In this study, cutting test was carried out to evaluate cutting performance of heavy flint glass using ultra-precision machine with single crystal diamond bite. The machined workpiece surface topography, tool wear and surface roughness were examined using AFM and SEM. The experimental results indicate that the machining mode become the brittle mode to ductile mode, when the maximum undeformed chip thinkness is large than critical value. Tool wear mainly occurs on the flank face and its wear mechanism is dominated by abrasion. This study demonstrates the feasibility of SF57HHT by diamond turning.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.460-469
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• 2000

A study on the corrosion behavior of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential and corrosion current density measurement of weld metal(WM), base metal (BM) and heat affected zone(HAZ), Al anode generating current and Al anode weight loss quantity in case of cathodic protection. And we carried out slow strain rate test(SSRT) in order to research mechanical properties such as stress at maximum load, percent strain, time to fracture and strain to failure ratio etc and to find out limiting cathodic polarization potential for hydrogen embrittlement with applied cathodic polarization potential. Hardness of HAZ part was the highest among those three parts and also galvanic corrosion susceptibility was the highest in HAZ part among those three parts due to the lowest corrosion potential than other parts. However corrosion current density was the highest in WM part among those three parts. And the optimum cathodic polarization potential showing the best mechanical properties obtained by SSRT method with applied constant cathodic potential was from - 770mV to - 875mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement on the mechanical properties was under - 900mV(SCE).

• Restorative Dentistry and Endodontics
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• v.38 no.1
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• pp.36-42
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• 2013

Objectives: This study evaluated the antibacterial effect and mechanical properties of composite resins ($L_{CR}$, $M_{CR}$, $H_{CR}$) incorporating chitosan with three different molecular weights (L, Low; M, Medium; H, High). Materials and Methods: Streptococcus (S). mutans 100 mL and each chitosan powder were inoculated in sterilized 10 mL Brain-Heart Infusion (BHI) solution, and was centrifuged for 12 hr. Absorbance of the supernatent was measured at $OD_{660}$ to estimate the antibacterial activities of chitosan. After S. mutans was inoculated in the disc shaped chitosan-containing composite resins, the disc was cleansed with BHI and diluted with serial dilution method. S. mutans was spread on Mitis-salivarius bacitracin agar. After then, colony forming unit (CFU) was measured to verify the inhibitory effect on S. mutans biofilm. To ascertain the effect on the mechanical properties of composite resin, 3-point bending and Vickers hardness tests were done after 1 and 3 wk water storage, respectively. Using 2-way analysis of variance (ANOVA) and Scheffe test, statistical analysis was done with 95% significance level. Results: All chitosan powder showed inhibition effect against S. mutans. CFU number in chitosan-containing composite resins was smaller than that of control resin without chitosan. The chitosan containing composite resins did not show any significant difference in flexural strength and Vickers hardness in comparison with the control resin. However, the composite resin, $M_{CR}$ showed a slightly decreased flexural strength and the maximum load than those of control and the other composite resins $H_{CR}$ and $L_{CR}$. Conclusions: $L_{CR}$ and $H_{CR}$ would be recommended as a feasible antibacterial restorative due to its antibacterial nature and mechanical properties.

• Journal of Korea Foundry Society
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• v.24 no.6
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• pp.356-365
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• 2004

Mechanical properties and microstructures of the Ni-AI-Fe and Ni-AI-Fe-(B, Zr) alloys which containing $10{\sim}30at$.%Fe, 0.1at.%B and/or 0.1at.%Zr have been investigated. The experimental results showed that the microstructures of Ni25Al were changed from a single phase ${\gamma}$ to dual phase ${\gamma}$ and ${\beta}$ by addition of 27at.%Fe. Ni45Al, however, kept the single ${\beta}$ phase even though Fe was added upto 30at.%. The hardness of Ni25Al were increased from $H_RB$ 70 to $H_RC$ 39 by addition of 27at.%Fe. In the case of Ni45Al which have $H_RC$ 37, the hardness was decreased by lOat.%Fe addition, but increased with 30at.%Fe. The yield strength and ultimate compressive strength in the compressive test have showed a similar trend with the hardness change. The strain to fracture was 14% at maximum and achieved in Ni25Al-27at.%Fe and Ni25Al-27at.%Fe-0.1 at.%B alloys. The Ni45Al showed a relatively low strain to fracture as 4%. The impact absorption energy of Ni25Al increased from 0.74 kg-m to 1.81 kg-m by addition of 27at.%Fe. In case of Ni45Al, the addition of lOat.%Fe and lOat.%Fe with small amounts of Band Zr did not change significantly the impact absorption energy of 0.60 kg-m, whereas the addition of 30at.%Fe with small amounts of B and Zr increased it slightly. In fracture tests, both of two basic materials showed the same intergranular fracture but by adding Fe it changed to the cleavage fracture mode or co-existing of cleavage and intergranular fractures.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.104-111
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• 2009

This paper shows the behaviors of macro- and micro-structures and mechanical properties for specimen's welding region welded by FSW. according to welding conditions with 5mm thickness aluminum 5083O alloy plate. It apparently results in defect-free weld zone in case traverse speed was changed to 32 mm/min under conditions of anti-clockwise direction and tool rotation speed such as 800 and 1250 rpm with tool's pin diameter of 5 ${\Phi}mm$ and shoulder diameter of 20 ${\Phi}mm$, pin length of 4.5 mm and tilting angle of $2^{\circ}$. The ultimate stress of ${\sigma}_T=331$ MPa and the yield point of 147 MPa are obtained at the condition of the travel speed of 32 mm/min with the tool rotation speed of 1250 rpm. There is neither voids nor cracks on bended surface of $180^{\circ}$ after bending test. The improvement of toughness after impact test was found. The lower rotating and traverse speed became, the higher were yield point, maximum stress and elongation(%) with the stresses and the elongation(%) versus the traverse speed diagram. Vickers hardness for cross section of welding zone were also presented. The typical macro-structures such as dynamically recrystallized zone, thermo-mechanically affected zone and heat affected zone and the micro-structures of the transverse cross-section were also showed. However, the author found out that the region of 6mm far away from shoulder circumference was affected by friction heat comprehensively, that is, hardness softened and that part of micro-structures were re-solid-solution or recrystallized, the author also knew that there is no mechanically deformation on heat affected zone but there are the flow of plastic deformation of $45^{\circ}$ direction on thermo-mechanically affected zone and the segregation of Al-Mg on nugget. The solid solution wt(%) of parent material as compared against of friction stir welded zone was comprehensively changed.

• Food Science of Animal Resources
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• v.40 no.4
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• pp.551-562
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• 2020

Beef fat was replaced with cold press pumpkin seed oil (PSO; 0%, 5%, 15%, and 20%) in the production of bologna-type sausages. A value of pH, water-holding capacity (WHC), jelly-fat separation, emulsion stability and viscosity values were determined in meat batters. Thiobarbituric acid reactive substances (TBARS), color, and textural characteristics (TPA, shear test, penetration test) were determined in end-product at 1, 7, 14, 21, and 28 days of storage at 4℃. The pH values were varied between 6.06 and 6.08. With the increase in the level of PSO in meat batters, there was a significant increase in WHC, jelly-fat separation and viscosity values (p<0.05) while a significant decrease in emulsion stability (p<0.05). TBARS values of sausages were found to be significantly higher than in the control group (p<0.05), and this trend continued during storage. Increasing of PSO level were caused a significant increase in L* and b* values while a decrease in a* value (p<0.05). Hardness, adhesiveness and chewiness values were significantly reduced whereas cohesiveness and resilience values increased (p<0.05). Maximum shear force and work of shear was significantly decreased as the level of PSO increased (p<0.05). Hardness, work of penetration and the resistance during the withdrawal of the probe values (penetration tests) increased significantly with the increase in the level of PSO (p<0.05). These results indicate that PSO has potential to be use as a replacement of animal-based fats in the production of bologna-type sausages.

• Polymer(Korea)
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• v.35 no.4
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• pp.342-349
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• 2011

The effect of the amount of vinyltriethoxysilane (VTEOS) in precipitated silica filled silicone rubbers was extensively investigated in terms of the change of mechanical properties, heat resistance, oil resistance, compression set, resilience, and curing characteristics. As the content of VTEOS increased from 0 to 2.0 phr, the hardness of the silicone rubber increased, however, tensile strength, elongation at break, and tear strength decreased. From heat resistance test, the change of mechanical properties was pronounced for silicone rubber treated with more VTOES. The best heat resistance was achieved at 2.0 phr VTOES. In addition, oil resistance was proportionally improved with VTEOS content. From oil resistance test. it was found that the decrease in hardness and maximum elongation was reduced for VTEOS-added systems. Finally, resilience, compression set, degree of cure and crosslink density were significantly enhanced with the amount of VTEOS.