• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.1
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• pp.112-117
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• 2013

We studied the modulation of pacemaker activities by Samchulkunbi-tang (SCKB) in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied SCKB produced membrane depolarization in the current-clamp mode. The pretreatment with $Ca^{2+}$-free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker potentials and suppressed the SCKB-induced action. The application of flufenamic acid (a nonselective cation channel blocker) abolished the generation of pacemaker potentials by SCKB. However, the application of niflumic acid (a chloride channel blocker) did not inhibit the generation of pacemaker potentials by SCKB. In addition, the membrane depolarizations were inhibited by not only GDP-${\beta}$-S, which permanently binds G-binding proteins, but also U-73122, an active phospholipase C inhibitor. These results suggest that SCKB modulates the pacemaker activities by nonselective cation channels and external $Ca^{2+}$ influx and internal $Ca^{2+}$ release via G-protein and phospholipase C-dependent mechanism. Therefore, the ICC are targets for SCKB and their interaction can affect intestinal motility.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.333-338
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• 2000

We have examined whether bile acids can affect the electrical and mechanical activities of circular smooth muscle of canine colon and ileum, using isometric tension measurement or patch clamp technique. It was found that a dilution of canine bile $(0.03{\sim}2%\;by\;volume)$ enhanced or inhibited the amplitude of spontaneous contractions. An individual component of bile, deoxycholic acid (DCA) enhanced the frequency and amplitude of the spontaneous contractile activity at $10^{-6}\;M,$ while DCA at $10^{-4}\;M$ inhibited the contraction. Similarly, the response to cholic acid was excitatory at $10^{-5}\;M$ and inhibitory at $3{\times}10^{-4}\;M.$ Taurocholic acid at $10^{-4}\;M$ enhanced the amplitude of muscle contraction. Electrically, canine bile at 1% reversibly depolarized the colonic myocytes under current clamp mode. Bile acids also elicited non-selective cation currents under voltage clamp studies, where $K^+$ currents were blocked and the $Cl^-$ gradient was adjusted so that $E_{Cl}^-$ was equal to -70 mV, a holding potential. The non-selective cation current might explain the depolarization caused by bile acids in intact muscles. Furthermore, the bile acid regulation of electrical and mechanical activities of intestinal smooth muscle may explain some of the pathophysiological conditions accompanying defects in bile reabsorption.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.302-311
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• 2005

We propose an improved active forward converter by adding a non-dissipative snubber circuit to the secondary of the conventional active clamp forward converter in this paper. The snubber circuit is composed of a tapped inductor, a snubber capacitor, and two diodes. Comparing with the conventional one, the proposed one makes it possible ZVS to operate in a smaller magnetizing current condition. The operational principles and the equivalent mode analysis of an improved active forward converter are mentioned in this paper. In conclusion, we constructed the prototype of the modified active forward converter with 300W output capacity and verified higher efficiency compared to the conventional one.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.103-110
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• 2010

In this paper, a new mode changeable asymmetric full bridge dc/dc converter is proposed to solve the freewheeling current problem of the conventional zero voltage switching(ZVS) phase shift full bridge(PSFB) dc/dc converter of low output voltage and high output current applications. The proposed converter is operated as an asymmetric full bridge converter when the duty cycle is less than 50% and active clamp full bridge converter when the duty cycle is greater than 50%. As a result, since its freewheeling current is eliminated, the conduction loss is lower than that of the conventional ZVS PSFB dc/dc converter. Moreover, ZVS of all power switches can be ensured along a wide load ranges and output current ripple is very small. Therefore, high efficiency of the proposed converter can be achieved. Especially since its operation mode is changed to the active clamp full bridge converter during hold up time and can be operated with 50~100% duty ratio, it can produce the stable output voltage along wide input voltage range. The operational principles, theoretical analysis and design considerations are presented. To confirm the operation, validity and features of the proposed converter, experimental results from a 1.2kW($400V_{dc}/12V_{dc}$) prototype are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.3
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• pp.37-44
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• 1998

This paper compared to the operation performance and efficiency of an interleaved active clap ZVS forward converter and an interleaved ZVS half-bridge converter in distributed power system. The design for the current-mode control circuit of an interleaved active clamp ZVS forward converter is presented. To simplify the gate drive circuits, N-P MOSFETs coupled active clamp method is proposed. An efficiency about 90% for the 50∼100% load range is achieved.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.807-810
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• 2004

This is a experimental result which is reported with using 16-Bit microprocessor H8 series of Renesas company, organizing digital control which is practicable PWM embodiment, and applying switched-mode power supply. The basic topology consists of the active clamp forward DC-DC converter which is widely used for the highly efficient power supply these days. In an experiment, it incites the result to lay emphasis on the highly efficient operation of converter, and performance of digital control which is practicable PWM embodiment. And it is debated on performance of processor and condition for improving performance of part.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.4
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• pp.183-190
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• 2003

We report the performance of an open-frame type low-voltage high-current DC-DC converter module developed using an active clamp forward converter circuit and current doubler rectifier. The converter module is designed with the specifications of an 1.8V output voltage, 25A output current, and 36-75V input voltage. The synchronous rectifier is used to reduce the conduction fuss at high current level and current-mode control is adapted to enhance the flexibility in the system configuration. A prototype converter module is successfully implemented within 10mm height and half brick size (58${\times}$61mm), and recorded an 84% efficiency and 4% voltage regulation for the entire input voltage range, thereby demonstrating its application potentials to future telecommunication electronics.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.183-183
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• 2003

We report the performance of an open-frame type low-voltage high-current DC-DC converter module developed using an active clamp forward converter circuit and current doubler rectifier. The converter module is designed with the specifications of an 1.8V output voltage, 25A output current, and 36-75V input voltage. The synchronous rectifier is used to reduce the conduction fuss at high current level and current-mode control is adapted to enhance the flexibility in the system configuration. A prototype converter module is successfully implemented within 10mm height and half brick size (58×61mm), and recorded an 84% efficiency and 4% voltage regulation for the entire input voltage range, thereby demonstrating its application potentials to future telecommunication electronics.

• Proceedings of the KIEE Conference
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• summer
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• pp.1269-1271
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• 2004

This is a thesis experiment result which is reported with using 16-Bit microprocessor H8 series of Renesas company, organizing digital control which is practicable PWM embodiment, and applying switched-mode power supply. The basic topology consists of the active clamp forward DC-DC converter which is widely used for the highly efficient power supply these days. In an experiment, it incites the result to lay emphasis on the highly efficient operation of converter, and performance of digital control which is practicable PWM embodiment. And it is debated on performance of processor and condition for improving performance of part.

• Clinical and Experimental Pediatrics
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• v.53 no.9
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• pp.845-851
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• 2010

Purpose: Recombinant human growth hormone (rhGH) has been widely used to treat short stature. However, there are some concerns that growth hormone treatment may induce skeletal maturation and early onset of puberty. In this study, we investigated whether rhGH can directly affect the neuronal activities of of gonadotropin-releasing hormone (GnRH). Methods: We performed brain slice gramicidin-perforated current clamp recording to examine the direct membrane effects of rhGH on GnRH neurons, and a whole-cell voltage-clamp recording to examine the effects of rhGH on spontaneous postsynaptic events and holding currents in immature (postnatal days 13-21) and adult (postnatal days 42-73) mice. Results: In immature mice, all 5 GnRH neurons recorded in gramicidin-perforated current clamp mode showed no membrane potential changes on application of rhGH (0.4, $1{\mu}g/mL$). In adult GnRH neurons, 7 (78%) of 9 neurons tested showed no response to rhGH ($0.2-1{\mu}g/mL$) and 2 neurons showed slight depolarization. In 9 (90%) of 10 immature neurons tested, rhGH did not induce any membrane holding current changes or spontaneous postsynaptic currents (sPSCs). There was no change in sPSCs and holding current in 4 of 5 adult GnRH neurons. Conclusion: These findings demonstrate that rhGH does not directly affect the GnRH neuronal activities in our experimental model.