• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.519-523
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• 2012

A kinetic study is reported on nucleophilic displacement reactions of benzyl 2-pyridyl carbonate 6 with alkalimetal ethoxides, EtOM (M = Li, Na, and K), in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of pseudo-firstorder rate constant $k_{obsd}$ vs. [EtOM] curve upward, a typical phenomenon reported previously for alkaline ethanolysis of esters in which alkali-metal ions behave as a Lewis-acid catalyst. The kobsd value for the reaction of 6 with a fixed EtOK concentration decreases rapidly upon addition of 18-crown-6-ether (18C6), a complexing agent for $K^+$ ion up to [18C6]/[EtOK] = 1.0 and then remains constant thereafter, indicating that the catalytic effect exerted by K+ ion disappears in the presence of excess 18C6. The reactivity of EtOM towards 6 increases in the order $EtO^-$ < EtOLi < EtONa < EtOK, which is contrasting to the reactivity order reported for the corresponding reactions of 2-pyridyl benzoate 4, i.e., $EtO^-$ < EtOK < EtONa < EtOLi. Besides, 6 is 1.7 and 3.5 times more reactive than 4 towards dissociated $EtO^-$ and ion-paired EtOK, respectively. The reactivity difference and the contrasting metal-ion selectivity are discussed in terms of electronic effects and transition-state structures.

• Journal of Intelligence and Information Systems
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• v.11 no.3
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• pp.129-139
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• 2005

The rapid growth of IT technologies enables the quality of human's daily life to be improved dramatically, Contrasting to the services in previous computing environment directed by user's request, the services in ubiquitous computing era of new IT technology are provided through recognizing users intention and utilizing context-aware information suited to the user. According to the contextual information, agents need to set a dynamic goal to achieve and work collaboratively with other agents. Agents that take control over their behaviors with capability of communicating with other agents become a thrust in this up-coming computing environment. This work focuses on building ontologies, shared knowledge bases among agents, to improve semantical interoperability among agents. More attention is given to the construction and effective management of ontology repository along with its requirement and organization. Ontology agent suggested takes an initiative role to manage the repository in a distributed manner and to facilitate the use of ontology in a multi-agent environment.

• Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.194-202
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• 2009

Sulfated fucans are known to have both anti-thrombotic and anti-coagulant activities. In this study, the variation in platelet aggregation and anti-coagulant activities was investigated in vitro with regard to administered dose, molecular weight distribution, sulfate content, and sugar composition in two algal fucoidans from Eisenia bicyclis and Undaria pinnatifida sporophylls (Mekabu). The anti-coagulant activity largely correlated with sulfate content and with molecular weight distribution in a dose-dependent manner. However, both fucoidans demonstrated inhibitory responses to ADP-induced platelet aggregation in dose- and structure-dependent manners that contrasted with the anti-coagulant activity. Neither molecular weight distribution nor sulfate content greatly affected platelet-aggregation inhibition (PA-inhibition) by the fucoidan fractions, whereas anti-coagulant activity was sensitive to these structural factors. Interestingly, an E. bicyclis fucoidan fraction exhibited almost complete PA-inhibition at a treatment dose of 500 mg/mL while retaining weak anti-coagulant activity. In conclusion, these observations suggest that fucoidan may be a useful anti-thrombotic or anti-platelet agent in various arterial thrombotic disorders, including post-vascular intervention with controlled bleeding complications, due to its anti-coagulant modulating activity.

• Journal of Life Science
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• v.17 no.7 s.87
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• pp.910-914
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• 2007

In order to synthesize new bioactive compounds and contrasting agents, reactions of glycine and glutamic acid as an animo acid with paraformaldehyde and hypophosphorous acid were executed. Products are 3,7-dihydroxy-3,7-dioxoperhydro-1,5,3,7-diazadiphosphocine-1,5-diacetic acid 1 and 3,7-dihydroxy-3,7- dioxoperhydre-1,5,3,7-diazadiphosphocine-1,5-di-(2-glu taric acid) 3. 2-[5-(1,2-Dicarboxyethyl)-3,7-dihydroxy-3,7-dioxo-315.715-[1,5,3,7] diazadiphosphocan-1-yl]-succinic acid 2 by using aspartic acid was not obtained. Esterification of 3,7- dihydroxy-3,7-dioxoperkydro-1,5,3,7-diaza-diphosphocine-1,5-diacetic acid 1 by treatment of methanol, ethanol, and propanol were executed. 3,7-Dihydroxy-3,7-dioxoperhydro-1,5,3,7-diazadiphosphocine-1,5-diacetic acid methyl ester 4, 3.7-dihydroxy-3,7-dioxoperhydro-1,5,3,f-diazadiphosphocine-1.5-diacetic acid ethyl ester 5, and 3,7-dihydroxy-3,7-dioxoperhydro-1,5,3,7-diazadiphosphocine-1,5-diacetic acid propyl ester 6 were respectively synthesized in good yields. Continuously, we will try synthesis of novel compounds and evaluation of biological activity.

• The Journal of Korean Medical History
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• v.29 no.2
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• pp.49-59
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• 2016

Ginseng, a Korean native herb, has been a symbol of mystic cure-all which provides longevity benefits throughout Korean history. According to Chinese historical records, a major source of wild ginseng has been described as Korean peninsula, which is the most suitable ginseng production area, and the Manchu region near Mt. Baekdu and the Maritime Province. Since Tang dynasty period (618-917 CE), Chinese has also called ginseng as "Goryeo Ginseng", which is named after "Goguryeo" (37 BCE-668 CE), an ancient kingdom of Korea, from which they mainly imported the herb as the region was famous for its high quality of ginseng. To date, it refers to Korean ginseng. This study compares the medicinal properties of ginseng as stated in the ancient Korean medical books with the major Korean historical records regarding the usage of ginseng and its symbolism of longevity in everyday life. By contrasting these findings, we tried to figure out how the actual medicinal properties of ginseng and the anticipation of longevity are related. It was confirmed that the expectations about longevity were widely applied to everyday life. In addition, the study investigates the various usage of ginseng as a motive for decorative patterns and as an ingredient for daily products including snacks, health drinks, various types of food, clothing patterns, and so on. Finally, the usage of ginseng ingredients in the cosmetic products fulfilled the desire of Korean people to purchase, showing the aesthetic recognition and medicinal understandings about the herb. These findings suggest that ginseng is an important medicinal agent that not only symbolizes longevity and good health but also has a great influence on the lives of Koreans.

• Journal of Ginseng Research
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• v.41 no.2
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• pp.180-187
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• 2017

Background: The incidence of halitosis has a prevalence of 22-50% throughout the world and is generally caused by anaerobic oral microorganisms, such as Fusobacterium nucleatum, Clostridium perfringens, and Porphyromonas gingivalis. Previous investigations on the structure-activity relationships of ginsenosides have led to contrasting results. Particularly, the antibacterial activity of less polar ginsenosides against halitosis-related bacteria has not been reported. Methods: Crude saponins extracted from the Panax quinquefolius leaf-stem (AGS) were treated at $130^{\circ}C$ for 3 h to obtain heat-transformed saponins (HTS). Five ginsenoside-enriched fractions (HTS-1, HTS-2, HTS-3, HTS-4, and HTS-5) and less polar ginsenosides were separated by HP-20 resin absorption and HPLC, and the antimicrobial activity and mechanism were investigated. Results: HPLC with diode-array detection analysis revealed that heat treatment induced an extensive conversion of polar ginsenosides (-Rg1/Re, -Rc, -Rb2, and -Rd) to less polar compounds (-Rg2, -Rg3, -Rg6, -F4, -Rg5, and -Rk1). The antimicrobial assays showed that HTS, HTS-3, and HTS-4 were effective at inhibiting the growth of F. nucleatum, C. perfringens, and P. gingivalis. Ginsenosides-Rg5 showed the best antimicrobial activity against the three bacteria, with the lowest values of minimum inhibitory concentration and minimum bactericidal concentration. One major reason for this result is that less polar ginsenosides can more easily damage membrane integrity. Conclusion: The results indicated that the less polar ginsenoside-enriched fraction from heat transformation can be used as an antibacterial agent to control halitosis.

• Korean Journal of Cognitive Science
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• v.27 no.3
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• pp.407-420
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• 2016

We live under the consequences of countless decisions, among which significant number of decisions is made by representatives acting on behalf of us. However, individuals often make disparate decisions depending on which identity they are assigned as an agent or with which opponent they are interplaying. In the current research, behavioral discontinuity depending upon actor identity and social relationship was investigated using the ultimatum game. Participants behaved in a more economically rational way when they acted as a group representative compared with when they made decisions as a private individual. However, the direction of the individual-representative discontinuity was reversed when rivalry came into play. Furthermore, more fairness was requested to accept the offers in the interaction with the rival compared with the neutral countergroup. Especially when interacting with the rival group, participants showed contrasting level of decision bias - measured by rejection rate toward unfair offers - according to the degree of mind attribution to the opponent. Specifically, the greater participants attributed a mind to the rival group, the more they rejected the unfair offers from it. The present research is important in that it provides insight into individuals' decision-making in a group context, which sometimes forgoes the financial gain of the entire group and ultimately leads to the sub-optimization of social welfare.