• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.307-312
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• 2022

It is well known that dopamine transmission from the ventral tegmental area (VTA) modulates motivated behavior and reinforcement learning. Although dopaminergic neurons are the major type of VTA neurons, recent studies show that a significant proportion of the VTA contains GABAergic and type 2 vesicular glutamate transporter (VGLUT2)-positive neurons. The non-dopaminergic neurons are also critically involved in regulating motivated behaviors. Some VTA neurons appear to co-release two different types of neurotransmitters. They are VGLUT2-DA neurons, VGLUT2-GABA neurons and GABA-DA neurons. These co-releasing neurons show distinct features compared to the neurons that release a single neurotransmitter. Here, we review how VTA cell populations wire to the other brain regions and how these projections differentially contribute to motivated behavior through the distinct molecular mechanism. We summarize the activities, projections and functions of VTA neurons concerning motivated behavior. This review article discriminates VTA cell populations related to the motivated behavior based on the neurotransmitters they release and extends the classical view of the dopamine-mediated reward system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.9
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• pp.1201-1208
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• 2001

Variable temperature anemometer(VTA) has greater sensitivity than a conventional constant temperature anemometer(CTA). In order to design a reliable VTA system, however, an elaborate photoconductive cell stabilizing circuit which plays a key role in setting wire-overheat ratio should be firstly developed. In this study, a stabilizing circuit which adopts proportional-integral analog controller was proposed and thoroughly tested for its accuracy and reproducibility. In contrast to the available circuit suggested by Takagi, the present circuit has characteristic that the resistance of a photoconductive cell increases with the increase of input voltage, which makes the current circuit very suitable for the design of VTA. Finally, VTA adopting stabilizing circuit was made and the enhanced sensitivity of the VTA was validated experimentally by comparing the calibration curves of VTA and CTA.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.99-104
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• 2000

Calibration equation for Variable Temperature Anemometer(VTA) has been tested for measured velocity-output data and the calibration process has been compared with that of Constant Temperature Anemometer(CTA). VTA has greater sensitivity than that of any other conventional anemometers, but to be more popular technique in flow field measurement, simple, accurate and well established calibration process should be suggested. To meet this purpose, similar calibration method used for CTA has been adopted for VTA and finally calibration equation for VTA including the effect of temperature drift has been proposed.

• Journal of the military operations research society of Korea
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• v.27 no.1
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• pp.101-113
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• 2001

Taguchi and VTA(variation Transmission Analysis) methods have been widely used recently as new methods for product design. In this study, Taguchi method using analysis of variance and VTA method using regression analysis are reviewed and compared with each other in terms of parameter design and tolerance design. In analysis of variance, variation of quality characteristics arises from noise factors, therefore the optimal levels of design factors are selected to minimize the effect of noise factors. n regression analysis, variation of quality characteristics arises from variation of each own design factors. As a method to reduce variation of these quality characteristics, sensitivity analysis was performed for each design factors. An example of calculating tolerance interval for the given defect rate in PPM is also introduced. Especially, the new method is suggested to increase the estimation accuracy of variation of quality characteristics through regression analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.663-668
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• 2010

In driving a car, turns such as left turns, right turns, or u-turns, make the speed of the car decrease considerably. A more straight path, therefore, is probably faster to arrive at the destination than zig-zag path with same distance. In this paper, we have newly proposed the turn heuristic to make more straight path. The path navigation algorithm with turn heuristic(called as TA* algorithm) could enhance the straightness of a path by putting the turned-edges to the turn cost. It requires higher cost to use TA* algorithm than traditional A* algorithm because the straight-edge first searching have increased the search space. We have improved the TA* algorithm into the variable TA* algorithm(called as VTA* algorithm) which adopt the turn-heuristic during the a portion of the whole path.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.10
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• pp.2678-2689
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• 1995

In this study, a new hot-wire anemometer which has greater sensitivity than that of a constant temperature anemometer (CTA) was proposed. In contrast to CTA, the wire working resistance of the new anemometer increases with flow velocity, that is, the operating mode of the wire becomes variable temperature. The variable temperature anemometer(VTA) was made by substituting a voltage controlled variable resistor such as photoconductive cell or transistor for one of the resistors in the bridge. By positively feeding back the bridge top signal to the input side of these electronic components, the wire overheat ratio could be increased with velocity automatically. Static response analyses of the VTA, constant voltage anemometer (CVA) and CTA were made in detail and calibration experiments were performed to validate the proposed operating principle. The wire operating resistance of the CVA decreases with velocity and this leads to lower sensitivity than that of a CTA. But the sensitivity of the newly proposed VTA is superior to that of a CTA, since the wire overheat ratio increases with velocity. Consequently, it is found that the major factor that is responsible for large sensitivity of a VTA is not the working resistance itself but the change of the wire working resistance with velocity.

• The Korea Journal of Herbology
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• v.24 no.1
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• pp.141-150
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• 2009

Objectives : The investigation of the antidepressant effects of Citri Reticulatae Viride Pericarpium (CR) Methods : we performed the forced swimming test. Also the expression of Tyrosine Hydroxylase (TH) was measured with immunohistochemical method at the Ventral Tegmental area (VTA), Locus coeruleus (LC). The Adrenocorticotropic Hormone (ACTH) level was measured in plasma. Results: 1. The duration of immobility in the forced swimming test was significantly decreased in the CR 100 mg/kg, CR 400 mg/kg groups, comparing with the control group (p < 0.05, p < 0.001). 2. TH expressions in the VTA, LC were significantly reduced in the CR 100mg/kg and CR 400mg/kg treated group, comparing with the control group (p < 0.05, p < 0.001). 3. ACTH expression in plama was significantly reduced in the CR 100 mg/kg treated group, comparing with the control group (p < 0.05). Conclusions : According to the above results, it can be considered that Citri Reticulatae Viride Pericarpium has antidepressant effect through the reduction of TH expression at VTA, LC and ACTH level in plasma.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.4
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• pp.139-144
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• 2007

Recent studies suggest that alterations in glutamate receptor subunit levels in mesocorticolimbic dopamine areas could account for neural adaptations in response to psychostimulant drugs. Although many drugs of abuse induce changes in ionotropic glutamate receptor subunits in mesocorticolimbic dopamine areas, the changes of ionotropic glutamate receptor subunits by repeated nicotine treatment in these areas are not known. To answer this question, we injected male Sprague-Dawley rats twice daily with nicotine (0.4 mg/kg) or saline (1 ml/kg) for 10 days. The immunoreactivity of NR1, GluR1, and GluR2 glutamate receptor subunits was examined $16{\sim}18 h$ after the last injection of saline or nicotine. Repeated nicotine treatment significantly increased NR1 levels in the ventral tegmental area (VTA). In addition, repeated nicotine treatment showed a tendency towards an increase in GluR1 levels in the VTA as well as in striatum. However, there was no significant change in glutamate receptor subunits in other areas including nucleus accumbens (NAc). These results demonstrate that repeated nicotine treatment increases NR1 levels in VTA similarly to other drugs of abuse, suggesting that elevated glutamate receptor subunits in the VTA, but not NAc may be involved in the excitation of mesocorticolimbic dopamine neurons by nicotine.

• The Korea Journal of Herbology
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• v.25 no.4
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• pp.61-67
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• 2010

Objectives : For the purpose of verifying the anti-depressant effect of Paeoniae Radix Rubra(PR), the expression of corticotropin-releasing factor(CRF), c-Fos and tyrosine hydroxylase(TH) was evaluated after performing the Forced Swimming Test(FST). Methods : Spraque-Dawley rats were ingested PR extract(100mg/kg, 400mg/kg, p.o.) for 3 times prior to FST. And the expression of corticotropin-releasing factor(CRF), c-Fos in the paraventricular nucleus(PVN) and tyrosine hydroxylase(TH) in the locus coelureus(LC) and ventral tegmental area(VTA) was measured immunohistochemically after FST. Results : The duration of immobility was significantly decreased in PR 100mg/kg Group and PR 400mg/kg Group, in comparison with the control group (p<0.001). The expression of CRF in the PVN was significantly decreased in PR 400mg/kg Group in comparison of the control group (p<0.05). The expression of c-Fos in the PVN was rather significantly increased in PR 100mg/kg Group in comparison with the control group, while almost no change was demonstrated in PR 400mg/kg Group. The expression of TH was significantly decreased in VTA in comparison with the control group (p<0.05), but the number of expression cells in LC was slightly decreased in case of PR 100mg/kg group while it was increased in case of PR 400mg/kg Group. Conclusion : Judging from the result of the aforementioned tests, Paeoniae Radix Rubra has decreased immobility. In addition, it has also decreased the expression of CRF and the expression of TH in VTA, while the expression of c-Fos and of TH in LC has no significance. Therefore, it is believed that Paeoniae Radix Rubra has an anti-depressant effect by decreased immobility through the reduced expression of CRF and TH in VTA.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.182-187
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• 2008

It needs to consider of turns during a path-finding on real road network. traveling on real road network, it generally takes less travel time in a more straight path than a zig-zaged path with same source and destination. In this paper, we propose $VTA^*$ algorithm that can reduce the cost of exploring despite increasing the number of turn in comparing with $TA^*$ algorithm. We have implement the proposed $VTA^*$, $TA^*$ which consider the number of turn and a traditional $A^*$ algorithm which dosen't consider the number of turn. The experimental result shows that the cost of exploring is reduced by 7.31 % comparing with $TA^*$ and the number of turn is reduced by 27.95% comparing with $A^*$ approximately.