• Development and Reproduction
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• v.24 no.4
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• pp.297-306
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• 2020

Repetitive changes in the intracellular calcium concentration ([Ca²⁺]i) triggers egg activation, including cortical granule exocytosis, resumption of second meiosis, block to polyspermy, and initiating embryonic development. [Ca²⁺]i oscillations that continue for several hours, are required for the early events of egg activation and possibly connected to further development to the blastocyst stage. The sources of Ca²⁺ ion elevation during [Ca²⁺]i oscillations are Ca²⁺ release from endoplasmic reticulum through inositol 1,4,5 tri-phosphate receptor and Ca²⁺ ion influx through Ca²⁺ channel on the plasma membrane. Ca²⁺ channels have been characterized into voltage-dependent Ca²⁺ channels (VDCCs), ligand-gated Ca²⁺ channel, and leak-channel. VDCCs expressed on muscle cell or neuron is specified into L, T, N, P, Q, and R type VDCs by their activation threshold or their sensitivity to peptide toxins isolated from cone snails and spiders. The present study was aimed to investigate the localization pattern of N and P/Q type voltage-dependent calcium channels in mouse eggs and the role in fertilization. [Ca²⁺]i oscillation was observed in a Ca²⁺ contained medium with sperm factor or adenophostin A injection but disappeared in Ca²⁺ free medium. Ca²⁺ influx was decreased by Lat A. N-VDCC specific inhibitor, ω-Conotoxin CVIIA induced abnormal [Ca²⁺]i oscillation profiles in SrCl₂ treatment. N or P/Q type VDC were distributed on the plasma membrane in cortical cluster form, not in the cytoplasm. Ca²⁺ influx is essential for [Ca²⁺]i oscillation during mammalian fertilization. This Ca²⁺ influx might be controlled through the N or P/Q type VDCCs. Abnormal VDCCs expression of eggs could be tested in fertilization failure or low fertilization eggs in subfertility women.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.482-488
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• 2013

Two piperazine-containing 3,4-dihyroquinazolines (BK10007S/8S) have been synthesized, based on our previous work on the synthesis and antitumoral activity of 3,4-dihyroquinazolines. After evaluating them for T-type calcium channel blocking effect and in vitro anti-cancer effect, they were profiled for acute and repeat dose toxicity (40 mg/kg, 2 weeks) to BALB/c mice. BK10007S/8S were further in vivo evaluated against human pancreatic MIA PaCa-2 carcinoma in $BALB/c^{nu/nu}$ nude mice, which exhibited 54 and 61% tumor growth inhibition through 57-day oral administration of 2 mg/kg of body weight, respectively.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.10
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• pp.21-29
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• 1999

This paper is concerning about the demapping method using the pilots inserted in transmitter in COFDM(Coded Orthogonal Frequency Division Multiplexing) demodulator which is the standard transmission method of terrestrial digital TV system in Europe(DVB-T). We have presented a simple and efficient method of CSI(Channel State Information) generation and demapping method using CSI. The CSI was derived from the pilot carriers inserted with comb-type among the received active carriers, which is defined as a SNR. From the simulation results for the 3 different constellations of the receiver, we could confirm that the system performance comparing with conventional soft decision method has been improved under DVB-T standard Rayleigh and Ricean fading channel.

• Journal of IKEEE
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• v.27 no.1
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• pp.45-52
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• 2023

Cold-junction correction(CJC) and disconnection detection circuit design of various thermocouples(TC) and multi-channel TC interface circuit using them were designed. The CJC and disconnection detection circuit consists of a CJC semiconductor device, an instrumentation amplifier(IA), two resistors and a diode for disconnection detection. Based on the basic circuit, a multi-channel interface circuit was also implemented. The CJC was implemented using compensation semiconductor and IA, and disconnection detection was detected by using two resistor and a diode so that IA input voltage became -0.42V. As a result of the experiment using R-type TC, the error of the designed circuit was reduced from 0.14mV to 3㎶ after CJC in the temperature range of 0℃ to 1400℃. In addition, it was confirmed that the output voltage of IA was saturated from 88mV to -14.2V when TC was disconnected from normal. The output voltage of the designed circuit was 0V to 10V in the temperature range of 0℃ to 1400℃. The results of the 4-channel interface experiment using R-type TC were almost identical to the CJC and disconnection detection results for each channel. The implemented multi-channel interface has a feature that can be applied equally to E, J, K, T, R, and S-type TCs by changing the terminals of CJC semiconductor devices and adjusting the IA gain.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.529-543
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• 2020

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca²⁺ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

• Clinical and Experimental Reproductive Medicine
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• v.27 no.1
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• pp.9-14
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• 2000

Objective: The sperm acrosome reaction is a $Ca^{2+}$-dependent exocytotic event that is triggered by adhesion to the mammalian egg's zona pellucida. Previous studies suggested a role of $Ca^{2+}$ channels in acrosome reactions. This study was conducted to investigate the T-type calcium channel is operated in acrosome reaction of human spermatozoa. Method: Human semen samples were obtained from healthy donors with normal criteria. The spermatozoa were divided into five groups: Group 1 were non-treated as a control; Group 2 where spermatozoa were exposed to 5 ${\mu}M$ $Ca^{2+}$ A23187 $(Ca^{2+}i)$; Group 3 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and mibefradil; Group 4 where spermatozoa were exposed 5 ${\mu}M$ $Ca^{2+}i$ and nifedipine, and Group 5 where spermatozoa were treated with 5 ${\mu}M$ $Ca^{2+}i$ and both of mibefradil and nifedipine. Spermatozoa in all groups were retrieved after incubation for 15 and 30 minutes at $37^{\circ}C$. After staining with PSA-FITC, fluorescence was observed under a fluorescence microscope, and AR was evaluated on a total>100 spermatozoa/side. Result and Conclusion: We observed on acrosome reaction inhibition rate in human spermatozoa the various of concentration of mibefradil, nifedipine. Maximum response was noted with 1.0 ${\mu}M$ mibefradil and the decrease of acrosome reaction inhibition rate 45%. Nifedipine in acrosome reaction inhibition rate was only about 25%. The $Ca^{2+}i$-induced AR of spermatozoa was significantly suppressed by mibefradil. Incidence of the suppression was depending on concentration of mibefradil. Results from the present study suggest that the human spermatozoa possess T-type channel. The observation that reversible inhibitor of T channels in male germ cells provides a new mechanism of contraceptive action.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.382-383
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• 2013

Gate-controlled spin-orbit interaction parameter is a key factor for developing spin-Field Effect Transistor (Spin-FET) in a quantum well structure because the strength of the spin-orbit interaction parameter decides the spin precession angle [1]. Many researches show the control of spin-orbit interaction parameter in n-type quantum channels, however, for the complementary logic device p-type quantum channel should be also necessary. We have calculated the spin-orbit interaction parameter and the effective mass using the Shubnikov-de Haas (SdH) oscillation measurement in a GaSb two-dimensional hole gas (2DHG) structure as shown in Fig 1. The inset illustrates the device geometry. The spin-orbit interaction parameter of $1.71{\times}10^{11}$ eVm and effective mass of 0.98 $m^0$ are obtained at T=1.8 K, respectively. Fig. 2 shows the gate dependence of the spin-orbit interaction parameter and the hole concentration at 1.8 K, which indicates the spin-orbit interaction parameter increases with the carrier concentration in p-type channel. On the order hand, opposite gate dependence was found in n-type channel [1,2]. Therefore, the combined device of p- and n-type channel spin transistor would be a good candidate for the complimentary logic device.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.221-226
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• 1997

This study was carried out for the hull form development of G/T 340ton class high speed fishery patrol ship by Chosun University at the Circulating Water Channel cooperatively with Korea Maritime Service. Same size of 15knots class fishery patrol ship was selected as a parent form (Model number : CU-015), and modified fore and after body to be suitable for the operation at 20 knots. To minimize the breaking wave in the vicinity of fore body at high speed zone, high bulb nose and slender fore body hull form was chosen as an initial condition. Meanwhile, to ensure the engine room space keeping high resistance-propulsion performance, U-type stern hull form was developed.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.4
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• pp.313-322
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• 2024

Mutations within the SCN5A gene, which encodes the α-subunit 5 (Na_V1.5) of the voltage-gated Na⁺ channel, have been linked to three distinct cardiac arrhythmia disorders: long QT syndrome type 3, Brugada syndrome (BrS), and cardiac conduction disorder. In this study, we have identified novel missense mutations (p.A385T/R504T) within SCN5A in a patient exhibiting overlap arrhythmia phenotypes. This study aims to elucidate the functional consequences of SCN5A mutants (p.A385T/R504T) to understand the clinical phenotypes. Whole-cell patch-clamp technique was used to analyze the Na_V1.5 current (I_Na) in HEK293 cells transfected with the wild-type and mutant SCN5A with or without SCN1B co-expression. The amplitude of I_Na was not altered in mutant SCN5A (p.A385T/R504T) alone. Furthermore, a rightward shift of the voltage-dependent inactivation and faster recovery from inactivation was observed, suggesting a gain-of-function state. Intriguingly, the co-expression of SCN1B with p.A385T/R504T revealed significant reduction of I_Na and slower recovery from inactivation, consistent with the loss-of-function in Na⁺ channels. The SCN1B dependent reduction of I_Na was also observed in a single mutation p.R504T, but p.A385T co-expressed with SCN1B showed no reduction. In contrast, the slower recovery from inactivation with SCN1B was observed in A385T while not in R504T. The expression of SCN1B is indispensable for the electrophysiological phenotype of BrS with the novel double mutations; p.A385T and p.R504T contributed to the slower recovery from inactivation and reduced current density of Na_V1.5, respectively.

• ETRI Journal
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• v.41 no.6
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• pp.829-837
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• 2019

The p-type nanowire field-effect transistor (FET) with a SiGe shell channel on a Si core is optimally designed and characterized using in-depth technology computer-aided design (TCAD) with quantum models for sub-10-nm advanced logic technology. SiGe is adopted as the material for the ultrathin shell channel owing to its two primary merits of high hole mobility and strong Si compatibility. The SiGe shell can effectively confine the hole because of the large valence-band offset (VBO) between the Si core and the SiGe channel arranged in the radial direction. The proposed device is optimized in terms of the Ge shell channel thickness, Ge fraction in the SiGe channel, and the channel length (L_g) by examining a set of primary DC and AC parameters. The cutoff frequency (f_T) and maximum oscillation frequency (f_max) of the proposed device were determined to be 440.0 and 753.9 GHz when L_g is 5 nm, respectively, with an intrinsic delay time (τ) of 3.14 ps. The proposed SiGe-shell channel p-type nanowire FET has demonstrated a strong potential for low-power and high-speed applications in 10-nm-and-beyond complementary metal-oxide-semiconductor (CMOS) technology.