• The Korean Journal of Physiology and Pharmacology
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• v.9 no.6
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• pp.347-352
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• 2005

The effects of nitric oxide (NO) on inhibitory neurotransmitter receptors and some types of inhibitory receptors in dissociated rod bipolar cell (RBC) were investigated. In the whole cell voltage-clamping mode, the gamma-aminobutyric acid (GABA) activated current showed both sustained and transient components. GABA activated transient current was fully blocked by bicuculine, a $GABA_A$ receptor antagonist. The cis-4-aminocrotonic acid (CACA), a $GABA_C$ receptor agonist, evoked the sustained current that was not blocked by bicuculline (BIC). Glycine activated the transient current. These results indicate that the RBCs possess $GABA_A$, $GABA_C$, and glycine inhibitory receptors. Sodium nitroprusside (SNP), a NO analogue, reduced the currents activated by $GABA_A$ receptor only, however, did not reduce the currents activated by either $GABA_C$ or glycine receptors. This study signifies further that only NO depresses the fast inhibitory response activated by $GABA_A$ receptor in RBC. We, therefore, postulate that NO might depress the light-on/off transient inhibitory responses in RBCs in the rat retina.

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.181-187
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• 2022

For carbon neutrality, direct-injection hydrogen engines are attracting attention as a future power source. It is essential to estimate the transient injection rate of hydrogen for the optimization of hydrogen injection in direct injection engines. However, conventional injection rate measurement techniques for liquid fuels based on the injection-induced fuel pressure change in a test section are difficult to be applied to gaseous fuels due to the compressibility of the gas and the sealing issue of the components. In this study, a momentum flux measurement technique is introduced to obtain the transient injection rate of gaseous fuels using a force sensor. The injection rate calculation models associated with the momentum flux measurement technique are presented first. Then, the volumetric injection rates are estimated based on the momentum flux data and the calculation models and compared with those measured by a volumetric flow rate meter. The results showed that the momentum flux measurement can detect the injection start and end timings and the transient and steady regimes of the fuel injection. However, the estimated volumetric injection rates showed a large difference from the measured injection rates. An alternative method is suggested that corrects the estimated injection rate results based on the measured mean volumetric flow rates.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.77-87
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• 2018

In the case of high-energy line breaks in nuclear power plants, supersonic steam jet is formed due to the rapid depressurization. The steam jet can cause impingement load on the adjacent structures, piping systems and components. In order to secure the design integrity of the nuclear power plant, it is necessary to evaluate the load characteristics of the steam jet generated by high-energy pipe rupture. In the design process of nuclear power plant, jet impingement load evaluation was usually performed based on ANSI/ANS 58.2. However, U.S. NRC recently pointed out that ANSI/ANS 58.2 oversimplifies the jet behavior and that some assumptions are non-conservative. In addition, it is recommended that dynamic analysis techniques should be applied to consider transient load characteristics. Therefore, it is necessary to establish an evaluation methodology that can analyze the dynamic load characteristics of steam jet ejected when high energy pipe breaks. This research group has developed and validated the CFD analysis methodology to evaluate the transient behavior of supersonic impinging jet in the previous study. In this study, numerical study on the transient load characteristics of supersonic steam jet impingement was carried out and amplitude and frequency analysis of transient jet load was performed.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.13-28
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• 2021

Since transient electronic devices can operate under harsh conditions such as electrolytic solutions or inside the body, and be removed by hydrolysis after operation, they can replace conventional electronic devices in various research areas like biomedical implantable devices. Moreover, transient electronic devices that can dissolve in water and enzymes are the focus of the new concept of green technology, which can solve electrical waste issues. However, the surroundings of transient electronic devices can deteriorate internal device components. Thus, an encapsulation strategy is introduced for stable operation in solution by shielding the outside of a device with a passive barrier. This article summarizes recent research trends in transient electronic devices, including their background, dissolution behavior, and encapsulation strategies to enhance reliability by blocking water permeation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.67-71
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• 1996

The dynamic equation is built by the mathematical modelling. The modelling is composed of various components used for the automatic transmission of tracked vehicles. When the transmission is shifting, the shock occurs in the drivetrain. The transient torques affect the durability and reliability of the vehicle. The factor and design point are analyzed for the transmission.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.842-847
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• 2010

Thermal analysis for the simulation of satellite component level thermal vacuum test processes was carried out by considering thermal vacuum test environment condition, thermal vacuum chamber configuration, and satellite's inner thermal environment. The transient analysis results can be obtained for the temperatures of component and thermal vacuum chamber assemblies. The thermal analysis model was verified with the component thermal environmental test results by using enhanced thermal vacuum chamber.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.5
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• pp.269-273
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• 2005

In horizontal cells (HCs) that were freshly dissociated from goldfish retina, two types of voltagedependent calcium currents ($I_{Ca}$) were recorded using a patch-clamping configuration: a transient type current and a sustained type current. The cell was held at -40 mV, and the prepulse step of -90 mV was applied before command pulse between -65 and +55 mV. The transient $Ca^{2+}$ current was activated by depolarization to around -50 mV from a prepulse voltage of -90 mV lasting at least 400 ms and reached a maximal value near -25 mV. On the other hand, the sustained $Ca^{2+}$ current was induced by pre-inactivation for less than 10 ms duration. Its activation started near -10 mV and peaked at +20 mV. $Co^{2+}$ (2 mM) suppressed both of these two components, but nifedipine ($20{\mu}M$), L-type $Ca^{2+}$ channel antagonist, blocked only the sustained current. Based on the activation voltage and the pharmacolog$I_{Ca}$l specificity, the sustained current appears to be similar to L-type $I_{Ca}$ and the transient type to T-type $I_{Ca}$. This study is the first to confirm that transient type $I_{Ca}$ together with the sustained one is present in HCs dissociated from goldfish retina.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.343-348
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• 2012

Blocking or regulating $K^+$ channels is important for investigating neuronal functions in mammalian brains, because voltage-dependent $K^+$ channels (Kv channels) play roles to regulate membrane excitabilities for synaptic and somatic processings in neurons. Although a number of toxins and chemicals are useful to change gating properties of Kv channels, specific effects of each toxin on a particular Kv subunit have not been sufficiently demonstrated in neurons yet. In this study, we tested electro-physiologically if heteropodatoxin2 ($HpTX_2$), known as one of Kv4-specific toxins, might be effective on various $K^+$ outward currents in CA1 neurons of organotypic hippocampal slices of rats. Using a nucleated-patch technique and a pre-pulse protocol in voltage-clamp mode, total $K^+$ outward currents recorded in the soma of CA1 neurons were separated into two components, transient and sustained currents. The extracellular application of $HpTX_2$ weakly but significantly reduced transient currents. However, when $HpTX_2$ was added to internal solution, the significant reduction of amplitudes were observed in sustained currents but not in transient currents. This indicates the non-specificity of $HpTX_2$ effects on Kv4 family. Compared with the effect of cytosolic 4-AP to block transient currents, it is possible that cytosolic $HpTX_2$ is pharmacologically specific to sustained currents in CA1 neurons. These results suggest that distinctive actions of $HpTX_2$ inside and outside of neurons are very efficient to selectively reduce specific $K^+$ outward currents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.100-108
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• 2008

The transient ground impedance depending on configuration, size, and material of grounding electrodes as well as the shapes of impulse currents, has a significant affect on the performance of the grounding system. This paper presents experimental results in regard to the analysis method of transient ground impedance using the lightning impulse and variable frequency currents. Also a new estimation method to replace the effective surge impedance for transient ground impedance was proposed. The ground electrodes used in this experiment are virtual ground electrodes including both resistance and inductance components, carbon ground electrode with 1[m] length, copper electrode with 9[m] length and counterpoise with 40[m] length. Ground impedances using the proposed method were measured respectively. Comparing with the ground impedance using variable frequency current the conventional ground impedance($Z_1$) calculated from the peak values of impulse voltage and impulse current is observed more correct method for evaluating the performance of ground electrode than the effective surge impedance.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.102-107
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• 2004

In general, major components of nuclear power plant have been evaluated based on 2-dimensional design codes conservatively. However, more exact assessment is necessary for continued operation beyond the design life. In this paper, 3-dimensional stress and fatigue analyses reflecting full geometry and monitored operating condition of reactor pressure vessel have been carried out. The analyses results showed that conservatism of current 2-dimensional evaluation based on design transient. Therefore, it is anticipated that the schemes developed from this research such as 3-dimensional finite element modeling, stress analysis and fatigue analysis related techniques can be utilized as fundamental tools for exact lifetime evaluation and license renewal of major nuclear components.