• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.460-466
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• 2007

There are two coordination functions in IEEE 802.11 standard. One is PCF, polling based function, and the other is DCF, contention based function. DCF is simpler than PCF but the performance is similar with the latter. That's the reason why DCF is more popular than PCF. However, DCF has a risk of collision with other nodes in the network because the function is a distributed contention based one. CSMA/CA of DCF has collision avoidance algorithm in it, but the performance of avoidance algorithm has limitations. In this paper we proposed a new scheme called TAR(Tone-based Access scheme with Repetitive conention). In TAR, there is narrow contention-only channel other than original data transmitting channel, so that both a data transmission and the contention can be performed simultaneously. The TAR uses the same contention concept with the CSMA/CA, but it has the originality for the narrow contention channel and the repetitive contention scheme which greatly reduce the collision probability. We proved the performance of TAR by some simulations, and it showed good results.

• Composites Research
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• v.34 no.1
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• pp.51-56
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• 2021

This paper studied the possibility of manufacturing bulk graphite using coal tar, a precursor of coal tar pitch, as a binder and impregnant. Carbonization was conducted after mixing and molding with natural graphite as a filler and coal tar as a binder. Impregnation-recarbonization was performed five times after carbonization. Coal tar used as impregnant. Measuring density, porosity, compressive strength, and anisotropy ratio was conducted. The maximum density of bulk graphite specimen was 1.76 g/㎤ and the minimum porosity was 15.6% which could be controlled by process control. The highest compressive strength was 20.3 MPa. Then the maximum anisotropic ratio of bulk was shown 0.34 through XRD analysis. Therefore, it was confirmed that it was possible to manufacture artificial graphite in a bulk form by using coal tar as a binder and an impregnant.

• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.57-63
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• 2011

This survey was conducted to develop an appropriate management for safety of children snacks. In this study, monitorings of food additives such as nine kinds of tar colors (tartrazine, sunset yellow FCF, brilliant blue FCF, indigo carmine, new coccine, amaranth, erythrosine, allura red and fast green FCF) which are sold at stationary store around the school, were performed. Eighty two samples (3 snacks, 71 candies, 4 chocolates and 4 beverages) were analyzed for tar colors. Results of risk assessment for tar colors were expressed as EDI (Estimated Daily Intake) comparing with ADI (Acceptable Daily Intake). The ratio of high risk group for tar color intake (95th) were 0-3.56%. The consumptions of tar colors from domestic and imported products for nine kinds of tar colors in candies were not significantly different. The results of this study indicated that each ED! of nine kinds of tar colors sold at stationary store around the school is much lower than each ADI in general. Consequently, the children snacks are thought to be safe for consumption.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.21-29
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• 2007

In Korea, we assign the chemical substances of 535 types as toxic substance. Only 10% of the 535 toxic substances are being managed by the Ministry of Environment related with water quality standard. Tar color is also one of chemical substances, but we have the lacks for the information of tar colors about the environmental effects of aquatic ecosystem. This study performed the test of bioassay using Water Fleas and Luminescent Bacteria. The tar has 7 types of colors allowed as the edible color and we evaluate the toxicities of 5 tar colors out of 7 colors and we would like to provide the informations for further study as we perform the toxicity test for the samples of 5 tar colors. We did the toxicity test of using Water Fleas From the results, we obtained the magnitudes of toxicity in order of Red No.2, Yellow No.5, Red No.3, Yellow No.4, Blue No.1. As the result based on Microtox Acute Toxicity Test using Luminescent Bacteria with the standard of 15min-EC50, we obtained in order of Yellow No.5, Food Red No.3, Red No.2, Yellow No.4, Blue No.1. We could expect the tar colors may have different effects on the aquatic ecosystem, respectively and it may influence to the aquatic ecosystem and the human, because of bioconcentration by food chain when toxicity of the tar colors overflow in the aquatic ecosystem.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.243-250
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• 2008

In Korean, nine tar colors are permitted in foods. This study assessed these compounds in the favorite food items of children found near elementary schools. A total of 439 items categorized under six food types were included in the analysis. The most frequently detected tar colors were tartrazine (Y4), Brilliant Blue FCF (Y5), Allura Red, and Sunset Yellow FCF, respectively. One or a mixture of two tar colors were commonly found in products such as gums, ice bars, soft drinks, and cereals. However, most often, combinations of two or three tar colors were detected. The levels of tar colors in candies, chocolates, gums, ice bars, cereals, and soft drinks were 0.11-1169.58 mg/kg, 0.73-468.02 mg/kg, 0.10-602.46 mg/kg, 0.25-162.32 mg/kg, 0.11-753.68 mg/kg, and 0.21-69.45 mg/kg, respectively. Tar color levels were higher in chocolates and gums than in soft drinks and ice bars. And Y4 and Y5 were detected at the highest levels. For ages 7-12, the total estimated daily intake (${\sum}EDI$) of each tar color ranged from 0.004 to 1.017 mg/day/person. These values were 0.02-5.98% of the FAO/WHO's acceptable daily intake (ADI).

• Korean Journal of Acupuncture
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• v.24 no.3
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• pp.149-164
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• 2007

Objectives : Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease in the gastrointestinal tract. The sources and pathologic mechanisms of IBD are still unknown. Moreover conventional therapies for IBD are not always effective, and they often have serious side effects. The purpose of this study is to examine the effect of Moxi-tar herbal acupuncture in IBD affected mice. Methods : Mice were treated with 5 % 2, 4, 6 - trinitrobenzenesulfonic acid (TNBS) on day 1 and day 7. To assume the preemptive effect and therapeutic effect, herbal acupuncture was practiced with Moxi-tar at BL25 (Daejangsu) on day 0, day 3, and day 6. The end of day in treatment with Moxi-tar herbal acupuncture, the mortality and the inflammatory factors of the colon were measured by the various methods. Results TNBS induced high mortality but herbal acupuncture with Moxi-tar at BL25 sup-pressed the mortality caused by TNBS. TNBS induced infiltration of immune cells in all layers of the colon and increased myeloperoxygenase (MPO) activity, while the treatment with Moxi-tar herbal acupuncture at BL25 suppressed the infiltration of immune cells and the increase of MPO activity caused by TNBS to normal levels, Herbal acupuncture with Moxi-tar regulated $NF-{\kappa}B$ activity, which is an important factor for the pathogenesis of chronic colitis, and reduced the expressions of $TNF-{\alpha}$, $IL-1{\beta}$, and ICAM-1 in the colons of TNBS treated mice. Furthermore herbal acupuncture suppressed macro- and micro- colonic damages caused by TNBS. Conclusions : This study demonstrates that herbal acupuncture with Moxi-tar at BL25 isa potential preemptive and/or therapeutic method targeting the chronic IBD.

• Food Science and Preservation
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• v.12 no.4
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• pp.355-360
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• 2005

This study was carried out to research the use of tar colors in children's favorite foods such as candies, soft drinks, chewing gums, cereals, and ice bars in order to acquire basic data on food safety. The tar colors were simultaneously analyzed by high performance liquid chromatography (HPLC). The contents of tar colors in candies, soft drinks, gums, cereals, and ice bars were maximum 74.10 mg/100 g, 5.96 mg/100 g, 35.70 mg/100 g, 20.10 mg/100 g, and 4.93 mg/100 g, respectively. In addition, every tar colors except for Indigo carmine (B2) and Fast Green FCF (G3) among permitted tar colors were used in foods and more than two kinds of tar colors were used in most cases. From the results, only types of tar colors for foods were regulated, but the amount was not regulated.

• IMMUNE NETWORK
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• v.2 no.3
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• pp.150-157
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• 2002

Background: Although Tat plays a role as a potent transactivator in the viral gene expression from the Human Immunodeficiency Virus type 1 long terminal repeat (HIV-1 LTR), it does not function efficiently in rodent cells implying the absence of a human specific factor essential for Tat-medicated transactivation in rodent cells. In previous experiments, we demonstrated that one of chimeric forms of TAR (transacting responsive element) of HIV-1 LTR compensated the restriction in rodent cells. Methods: To characterize the nature of the compensation, we tested the effects of several upstream binding factors of HIV-1 LTR by simple substitution, and also examined the role of the configuration of the upstream binding factor(s) indirectly by constructing spacing mutants that contained insertions between Sp1 and TATA box on Tat-mediated transactivation. Results: Human Sp1 had no effect whereas its associated factors displayed differential effects in human and rodent cells. In addition, none of the spacing mutants tested overcame the restriction in rodent cells. Rather, when the secondary structure of the chimeric HIV-1 TAR construct was destroyed, the compensation in rodent cells was disappeared. Interestingly, the proper interaction between Sp1 and TATA box binding proteins, which is essential for Tat-dependent transcription, was dispensable in rodent cells. Conclusion: This result suggests that the human-specific Tat cofactor acts to allow Tat to interact effectively in a ribonucleoprotein complex that includes Tat, cellular factors, and TAR RNA, rather than be associated with the HIV-1 LTR upstream DNA binding factors.

• Textile Coloration and Finishing
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• v.17 no.4 s.83
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• pp.27-34
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• 2005

In order to prepare acetate nano filter for the adsorption of nicotine/tar in tobbaco, acetate nano fiber was fabricated by elecrospining from acetate solution dissolved in acetone/DMAc(2/1). Above a critical polymer concentration($15\%$), the nano fiber was formed. The average diameter of nano fiber was decreased with the applied voltage and increased with the feeding rate. Appropriate spinning condition was considered to be $15wt\%$ polymer concentration, 11.25kV applied voltage, 0.6ml/h feeding rate, and 13-15cm TCD. Using the nano fiber, acetate nano filter was fabricated. It showed good nicotine/tar adsorption ability compared with general tobbaco filter. It was considered that the increase of surface area and the development of microporous structure in filter was much affected to the adsorption of nicotine/tar.

• Carbon letters
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• v.25
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• pp.78-83
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• 2018

Pyrolyzed fuel oil (PFO) and coal tar was blended in the feedstock to produce pitch via thermal reaction. The blended feedstock and produced pitch were characterized to investigate the effect of the blending ratio. In the feedstock analysis, coal tar exhibited a distinct distribution in its boiling point related to the number of aromatic rings and showed higher Conradson carbon residue and aromaticity values of 26.6% and 0.67%, respectively, compared with PFO. The pitch yield changed with the blending ratio, while the softening point of the produced pitch was determined by the PFO ratio in the blends. On the other hand, the carbon yield increased with increasing coal tar ratio in the blends. This phenomenon indicated that the formation of aliphatic bridges in PFO may occur during the thermal reaction, resulting in an increased softening point. In addition, it was confirmed that the molecular weight distribution of the produced pitch was associated with the predominant feedstock in the blend.