• 한국도로학회논문집
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• 제18권3호
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• pp.67-74
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• 2016

PURPOSES : This study evaluated the field applicability and laboratory performance of glass fiber-reinforced asphalt (GFRA) mixtures. METHODS : The general hot-mix asphalt (HMA) and GFRA mixtures were paved in five sites, including three national highways, one express highway, and an arterial road, to evaluate field applicability and durability. The plant mixing and construction method for the GFRA were similar to those for the general HMA. The lab performances of the field samples were relatively compared through the mechanical measures from the Marshall stability, indirect tensile strength, and dynamic stability. The field performance was surveyed after a year. RESULTS : The lab tests verified the superior lab performances of the GFRA compared to the general HMA. The Marshall stability of the GFRA increased for about 128% of the general HMA. The indirect tensile strength of the GFRA was 115% greater than that of the general HMA. The dynamic stability of the GFRA resulted in 16,180 reps/mm, which indicated that high rut resistance may be expected. No noticeable defects, such as cracks or deformation, were observed for the GFRA sections after a year. CONCLUSIONS : The lab tests and field survey for the five GFRA sites resulted in superior performances compared to the general HMA. The relatively low-cost GFRA, which required no pre-processing procedures, such as polymer modification, may be a promising alternative to the polymer-modified asphalt mixtures. The long-term performance will be verified by the superior field durability of the GFRA in the near future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.185-201
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• 2023

Grant-free random access (GFRA) can reduce the access delay and signaling cost, and satisfy the short transmission packet and strict delay constraints requirement in internet of things (IoT). IoT is a major trend in the future, which is characterized by the variety of applications and devices. However, most existing studies on GFRA only consider a single type of device and omit the effect of access delay. In this paper, we study GFRA in multicell massive multipleinput multiple-output (MIMO) systems where different types of devices with various configurations and requirements co-exist. By introducing the backoff mechanism, each device is randomly activated according to the backoff parameter, and active devices randomly select an orthogonal pilot sequence from a predefined pilot pool. An analytical approximation of the average spectral efficiency for each type of device is derived. Based on it, we obtain the optimal backoff parameter for each type of devices under their delay constraints. It is found that the optimal backoff parameters are closely related to the device number and delay constraint. In general, devices that have larger quantity should have more backoff time before they are allowed to access. However, as the delay constraint become stricter, the required backoff time reduces gradually, and the device with larger quantity may have less backoff time than that with smaller quantity when its delay constraint is extremely strict. When the pilot length is short, the effect of delay constraints mentioned above works more obviously.

• 한국동물생명공학회지
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• 제35권4호
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• pp.289-296
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• 2020

Spermatogonial stem cells are self-renewal and differentiate into sperm in post-pubertal mammals. There exists a balance between the self-renewal and differentiation in the testes. Spermatogonial stem cells make up only 0.03% of testicular cells in adult mice. These cells maintain sperm production by differentiating after puberty. Therefore, analyzing the expression of genes associated with spermatogenesis is critical for understanding differentiation. The present study aimed to establish the postnatal period of cells in relation to spermatogenesis. To study the expression of differentiated and undifferentiated marker genes in enriched spermatogonial stem cells, in vitro culture was performed and cells from pup (6-8-day-old) and adult (4-months-old) testicular tissues were isolated. As a result, undifferentiated genes, Pax7, Plzf, GFRa1, Etv5 and Bcl6b, were highly increased in cultured spermaotogonial stem cells compared with pup and adult testicular cells. On the other hands, differentiated gene, c-kit was highly increased in adult testicular cells, Also Stra8 gene was highly increased in pup and adult testicular cells. This study provides a better understanding of spermatogenesis-associated gene expression during postnatal periods.

• Clinical and Experimental Reproductive Medicine
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• 제51권3호
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• pp.213-224
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• 2024

Objective: Some age-related testicular changes, such as Sertoli cell vacuolization and blood-testis barrier breakdown, reduce total sperm production and male fertility. Therefore, this study investigated the effect of vitamin E on restoring testicular function in aged mice. Sperm cryo-resistance was also assessed. Methods: Twenty-eight 48-week-old male Naval Medical Research Institute mice were divided into four groups for a daily gavage of vitamin E: the control group received distilled water, while the three treatment groups were administered 100, 200, and 400 mg/kg, respectively, for 4 weeks. Subsequently, semen analyses, DNA fragmentation index (DFI), and protamine deficiency tests were conducted. Testicular histology, tissue antioxidant enzyme activity, and gene expression levels were also assessed. Results: The two higher dosages of vitamin E were associated with a higher sperm count, greater progressive motility, and improved sperm morphology (p<0.05). These benefits were also evident after sperm freezing (p<0.05). Although chromatin abnormalities increased following vitrification, the treatment groups showed better outcomes (p<0.05). The tubular diameter, epithelium height, and luminal diameters remained unchanged with age. The tissue antioxidant capacity was greater in the groups receiving the high doses of vitamin E. Additionally, significant increases in inhibitor of DNA binding protein-4 (Id4) and GDNF family receptor alpha-1 (Gfra1) expression were observed in the higher vitamin E dosage groups, and promyelocytic leukemia zinc finger protein (Plzf) expression was notably present in the 400 mg/kg treatment group compared to the control group (p<0.05). Conclusion: Antioxidant supplementation might enhance reproductive outcomes in aging males. The observed effects included improved sperm cryo-resistance, which is advantageous for future applications such as sperm freezing or fertility preservation.