• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.16-27
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omni-directional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a reliable broadcast protocol in link taller based on directional antennas, named MDB(MAC protocol for Directional Broadcasting). This protocol makes use of DAST(Directional Antennas Statement Table) information and D-MACA(Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to resolve the many collision problem wit]1 omni-directional antenna. To analyze its performance, MDB protocol is compared with IEEE 802.11 DCF protocol [9] and the protocol 2 of reference [3], in terms of the success rate of broadcast and the collision rate. As a result of performance analysis through simulation, it was confirmed that the collision rate of the MDB protocol is lower than those of IEEE 802.11 and the protocol 2 of reference [3], and that the completion rate of broadcast of MDB protocol is higher than those of IEEE 802.11 and the protocol 2 of reference [3].

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.88-99
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• 2017

This study investigated the clinical characteristics of the Internet addiction risk group using MMPI-2 and discussed whether the MMPI-2 can be used for diagnosis, evaluation and intervention of the Internet addiction risk group. We verified the difference in the MMPI-2 scales between the addiction-risk group and the general user group, and verified whether the substance-related scales MAC-R, AAP, and AAS scales can distinguish between Internet addiction risk group and general users. The results of the analysis of the MMPI-2 characteristics of 39 Internet addiction risk group and 21 general user group who visited internet addiction counseling center showed significant difference in the D, Pa, Pt, Sc, and Si scales on the clinical scale. There was no difference in the MAC-R, AAS, and APS scales between the Internet addiction group and the general user group. This suggests, that it is not possible to screen the Internet addiction risk group with the supplementary measure, and it is necessary to develop a new scale to diagnose internet addiction.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.21 no.2
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• pp.89-107
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• 2017

In this paper, we have proposed a modified Marker-And-Cell (MAC) method to investigate the problem of an unsteady 2-D incompressible flow with heat and mass transfer at low, moderate, and high Reynolds numbers with no-slip and slip boundary conditions. We have used this method to solve the governing equations along with the boundary conditions and thereby to compute the flow variables, viz. u-velocity, v-velocity, P, T, and C. We have used the staggered grid approach of this method to discretize the governing equations of the problem. A modified MAC algorithm was proposed and used to compute the numerical solutions of the flow variables for Reynolds numbers Re = 10, 500, and 50000 in consonance with low, moderate, and high Reynolds numbers. We have also used appropriate Prandtl (Pr) and Schmidt (Sc) numbers in consistence with relevancy of the physical problem considered. We have executed this modified MAC algorithm with the aid of a computer program developed and run in C compiler. We have also computed numerical solutions of local Nusselt (Nu) and Sherwood (Sh) numbers along the horizontal line through the geometric center at low, moderate, and high Reynolds numbers for fixed Pr = 6.62 and Sc = 340 for two grid systems at time t = 0.0001s. Our numerical solutions for u and v velocities along the vertical and horizontal line through the geometric center of the square cavity for Re = 100 has been compared with benchmark solutions available in the literature and it has been found that they are in good agreement. The present numerical results indicate that, as we move along the horizontal line through the geometric center of the domain, we observed that, the heat and mass transfer decreases up to the geometric center. It, then, increases symmetrically.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.5
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• pp.621-629
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• 2012

This study aimed to examine the possibility of data from pulse diagnosis device to be used for diagnosis of Sasang constitution. Systematic searches of 5 major Korean medical database were conducted for articles published up to May 2012. Searching key word was "Sasang" or "Constitution". Studies dealt with correlation between Sasang constitution and the pulse wave data from pulse diagnosis machine were included. Totally 2886 studies are searched and 3 studies are added from references of evaluated articles. Among them, 12 studies were met our inclusion criteria (2 Xishu Mac, 2 Self-made pulse diagnosis machine, 8 3D-Mac). Three of the eight 3D-Mac studies intended to develop a formula of constitutional differential diagnosis, 2 studies compared variables by Sasang constitution in healthy group and 3 studies compared variables by Sasang constitution in healthy group and special disease group. They all reported some significant variables, however results are not consistent between studies. The accuracy of the formula of constitutional differential diagnosis using 3D-Mac pulse diagnosis devices is 46.0% by now. Improvements in measuring pulse are required to achieve more accurate result and be used for diagnosis of Sasang constitution. Compensating B.M.I. among Sasang constitutional groups and separating constitutional pulse factors from acquired characteristics are also needed in further study.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.328-331
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• 2013

Incentive/Disincentive (I/D) contracting experiences in many states have been evaluated in terms of time and cost performance and substantial project time savings were found in many project cases. However, there is little understanding on individual project success factors for I/D projects during construction. This paper explores the significance of I/D clause in the success of the MacArthur Maze reconstruction project and summarizes a list of group causes that explains and elaborates on the detailed factors. The methods used for carrying out this study started with a search of online media and news reports and contract documents were also obtained from Caltrans. After review of the preliminary information, Interviews were performed with the Caltrans Resident Engineer and the contractor's project manager who were in charge of the MacArthur Maze reconstruction. In conclusion, the evaluation of their responses hinted at six significant cause groups responsible for the project's success. These groups can be listed as: 1) Motivation, 2) Policy, 3) Teamwork, 4) Communication, 5) Expectation, and 6) Resource Management.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1145-1147
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• 1998

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1521-1523
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• 1999

• The Korean Journal of Financial Studies
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• v.2 no.2
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• pp.133-169
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• 1995

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.6
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• pp.1012-1022
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• 2020

Objective: Caseins and fatty acids of milk are synthesized and secreted by the epithelial cells of the mammary gland. All-trans retinoic acid (ATRA), an active metabolite of vitamin A, has been shown to promote mammary development. This study was conducted to determine the effect of ATRA on casein synthesis and fatty acid composition in MAC-T cells. Methods: MAC-T cells were allowed to differentiate for 4 d, treated with ATRA (0, 1.0, 1.5, and 2.0 μM), and incubated for 3 d. We analyzed the fatty acid composition, the mRNA expression of casein and fatty acid synthesis-related genes, and the phosphorylation of casein synthesis-related proteins of MAC-T cells by gas chromatography, quantitative polymerase chain reaction, and western blotting, respectively. Results: In MAC-T cells, ATRA increased the mRNA levels of α_S1-casein and β-casein, janus kinase 2 (JAK2) and E74-like factor 5 of the signal transducer and activator of transcription 5 β (STAT5-β) pathway, ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic translation initiation factor 4E binding protein 1 of the mammalian target of rapamycin (mTOR) pathway, inhibited the mRNA expression of phosphoinositide 3-kinase and eukaryotic initiation factor 4E of the mTOR pathway, and promoted the phosphorylation of STAT5-β and S6K1 proteins. Additionally, ATRA increased the de novo synthesis of fatty acids, reduced the content of long-chain fatty acids, the ratio of monounsaturated fatty acids to saturated fatty acids (SFA), the ratio of polyunsaturated fatty acids (PUFA) to SFA, and the ratio of ω-6 to ω-3 PUFA. The mRNA levels of acetyl-CoA carboxylase 1, fatty acid synthase, lipoprotein lipase, stearoyl-CoA desaturase, peroxisome proliferator-activated receptor gamma, and sterol regulatory element-binding protein 1 (SREBP1) were enhanced by ATRA. Conclusion: ATRA promotes the synthesis of casein by regulating JAK2/STAT5 pathway and downstream mTOR signaling pathway, and it improves the fatty acid composition of MAC-T cells by regulating SREBP1-related genes.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.878-885
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• 2017

Objective: Glucose is an essential fuel in the energy metabolism and synthesis pathways of all mammalian cells. In lactating animals, glucose is the major precursor for lactose and is a substrate for the synthesis of milk proteins and fat in mammary secretory (alveolar) epithelial cells. However, clear utilization of glucose in mammary cells during lactogenesis is still unknown, due to the lack of in vitro analyzing models. Therefore, the objective of this study was to test the reliability of the mammary alveolar (MAC-T) cell as an in vitro study model for glucose metabolism and lactating system. Methods: Undifferentiated MAC-T cells were cultured in three types of Dulbecco's modified Eagle's medium with varying levels of glucose (no-glucose: 0 g/L, low-glucose: 1 g/L, and high-glucose: 4.5 g/L) for 8 d, after which differentiation to casein secretion was induced. Cell proliferation and expression levels of apoptotic genes, Insulin like growth factor-1 (IGF1) receptor, oxytocin receptor, ${\alpha}S1$, ${\alpha}S2$, and ${\beta}$ casein genes were analyzed at 1, 2, 4, and 8 d after differentiation. Results: The proliferation of MAC-T cells with high-glucose treatment was seen to be significantly higher. Expression of apoptotic genes was not affected in any group. However, expression levels of the mammary development related gene (IGF1 receptor) and lactation related gene (oxytocin receptor) were significantly higher in the low-glucose group. Expressions of ${\alpha}S1-casein$, ${\alpha}S2-casein$, and ${\beta}-casein$ were also higher in the low-glucose treated group as compared to that in the no-glucose and high-glucose groups. Conclusion: The results demonstrated that although a high-glucose environment increases cell proliferation in MAC-T cells, a low-glucose treatment to MAC-T cells induces higher expression of casein genes. Our results suggest that the MAC-T cells may be used as an in vitro model to analyze mammary cell development and lactation connected with precise biological effects.