• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.591-610
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• 2020

Concrete with activated carbon and titanium dioxide (TiO₂) has been used to reduce the particulate matter (PM) in underground structures (e.g., tunnels) due to the high performance of nitrogen oxides (NOx) abatement. Damage (e.g. crack, spalling, or detachment) can be caused by the environmental and ageing effects on the surface of the particulate matter reduction concrete, installed on the tunnel lining. Therefore, it is important to evaluate the existence of spalling on the concrete surface for maintaining performance of NOx reduction. In this study, a basic research was performed for feasibility of spalling evaluation using electrical resistivity characteristics. Given the test results, the electrical resistivity was decreased as the ratios of activated carbon (0~15%) and TiO₂ (0~25%) were increased for specimens. Under a dry condition, electrical resistivity of cement specimens, mixed with activated carbon and TiO₂, was decreased up to 2.3 times, compared with the normal cement specimen. In addition, under saturation conditions (degree of saturation: 85~98%), electrical resistivity of cement specimens with activated carbon, was decreased up to 3.5 times, compared with the normal cement specimen. Regardless of the condition (dry or saturated), the difference of electrical resistivity values shows the range of 2.3~2.8 times between the mixing specimen (with activated carbon (15%) and TiO₂ (25%)) and the normal cement specimen. This study can help to provide basic knowledge for spalling evaluation using the electrical resistivity on the surface of the particulate matter reduction concrete in tunnels.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.659-666
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• 2004

This study was conducted to assess objective and subjective meat quality traits for imported chilled beef with a high degree of marbling in longissimus muscle with reference to Hanwoo beef Muscle samples of four Wagyu, four Angus, four Hanwoo grade 1, and three Hanwoo grade 3 were purchased from a commercial beef market. The meats had intramuscular fat content of approximately 22, 8, 13 and 4%, and aged for 31, 71, 14 and 14 days, respectively. Imported beef showed a significantly(P<0.05) lower WB-shear force than Hanwoo. However, the instrument measurement did not reflect sensory tenderness and juiciness, which were similar between the four groups. On the other hand, Hanwoo beef showed significantly(P<0.05) favorable flavor intensity. This was likely an indication of more a desirable eating quality for Hanwoo beef, regardless of the level of intramuscular fat content. Discriminant functions of C18: 0, C18: In-7, C18: In-9, C20: 3n-6, C20 : 4n-6 and total n-3 polyunsaturated fatty acids classified the domestic and foreign beef products at 100%, despite a noticeable difference between two groups existed only in C18:0. Principle component analysis indicated that subjective flavor intensity was negatively related to C18: 0 and C18: ln-7. The result indicated that C18: 0 could be a possible candidate fatty acid for difference in flavor intensity between two beef groups. The current study demonstrated that the domestic product was more acceptable for Korean consumers. However, it was not identified whether the result was associated with breed, feeding regime, or ageing time. Further studies are required for breed specification in terms of sensory characteristics and consumer preference.

• Journal of Animal Science and Technology
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• v.46 no.3
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• pp.427-436
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• 2004

The current study was conducted to determine the effect of suspension method on satisfaction level of Korean consumers and objective meat quality traits in Hanwoo longissimus dorsi(LD), triceps brachii(TB) and semimembranosus(SM) muscles. Eighteen Hanwoo steers were slaughtered and alternative sides were hung either by pelvic bone(TS) or Achilles tendon(Al). Sensory characteristics, WB-shear force, sarcomere length, water-holding capacity, saroomere length and cooking loss were determined after a 7-d chiller ageing. Higher carcass quality grade received significantly(p < 0.05) greater eating quality for LD, but the grade did not affect eating quality for both TB and SM. TS did not influence objective and subjective meat quality for TB, but that significantly(P < 0.05) improved eating quality for LD and SM. The most noticeable result was that when SM was tenderstretehed, eating quality was equivalent to that of nonna1ly hung LD. In relationship between objective and subjective meat quality assessments, eating qualty for LD had a significant(P < 0.05) relationship with intramuscular fat content, while that for SM was greatly(P < 0.05) related to saroomere length. The current study indicated that pelvic hanging was an effective way to improve eating quality both LD and SM, and carcass quality grades did not greatly reflect eating quality of SM and TB. The data also implied that instnunental measurements poorly estimated the satisfaction level of Korean conswners.