• Transactions of the Korean hydrogen and new energy society
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• v.12 no.2
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• pp.129-136
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• 2001

An investigation on the A/V(ampere/volt) gradient according to the concentration and the kind of solution in a electrolyzer is carried out to obtain the basic data on the ultrasonic application for the efficiency elevation of the hydrogen fuel production. KOH is selected as an electrolyte and concentrations are 0%, 10%, 20% and 30%. The solutions are city water, city water with nitrogen. distilled water and distilled water with nitrogen. The Electrochemical analyzer(BAS Co.) is used as a measuring device to observe the A/V gradient. And the limit of volt is from -3000mV to +3000mV. The 28kHz magnetic transducer is selected to give them ultrasonic forcing. In results, it is clarified that ultrasonic influences the A/V gradient in the electrolytic solution.

• Membrane and Water Treatment
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• v.13 no.2
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• pp.63-72
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• 2022

Choline chloride-glycerol (1:2 mol), a natural deep eutectic solvent (NADES) is examined as a draw solution in forward osmosis (FO) for dewatering application. The NADES is easy to prepare, low in toxicity and environmentally benign. A polyamide thin film composite membrane was used. Characterization of the membrane confirmed porous membrane structure with good hydrophilicity and a low structural parameter (722 ㎛) suitable for FO application. A dilute solution of 20% (v/v) NADES was enough to generate moderate water flux (14.98 L m^-2h^-1) with relatively low reverse solute flux (0.125 g m^-2h^-1) with deionized water feed. Application in dewatering industrial wastewater feed showed reasonably good water flux (11.9 L m^-2h^-1) which could be maintained by controlling the external concentration polarization and fouling/scaling mitigation via simple periodic deionized water wash. In another application, clarified sugarcane juice could be successfully concentrated. Recovery of the draw solute was accomplished easily by chilling utilizing thermo responsive phase transition property of NADES. This study established that low concentration NADES can be a viable alternative as a draw solute for dewatering of wastewater and other heat sensitive applications along with a simple recovery process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.630-634
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• 2004

This paper describes the design of a two stage 1V power supply SiGe Low Noise Amplifier operating at 5.25 GHa for 802.lla wireless LAN application. The achieved performance includes a gain of 17 ㏈, noise figure of 2.7㏈, reflection coefficient of 15 ㏈, IIP3 of -5 ㏈m, and 1-㏈ compression point of -14㏈m. The total power consumption of the circuit was 7 mW including 0.5mW for the bias circuit.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.527-537
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• 1995

The effect of calcitonin gene-related peptide (CGRP), substance P (SP) and electrical stimulation of the tooth on the intradental nerve activtiy (INA) was investigated in anesthetized cats. The INA was recorded from single pulp nerve units dissected from the inferior alveolar nerve under stereomicroscope. The INA elicited by 3 minute application of 4M NaCl in deep dentinal cavity was compared before and after stimulation at 10 minute intervals. The magnitude of INA was calculated as the total number of nerve impulses produced in given period, and the changes of INA are expressed as % of control INA. The results obtained were as follows. 1. 16 single pulp nerve units were classified as 14 $A{\delta}$-fibers (3.4~19.4m/sec) and 2-fibers (1.5~1.7m/sec) according to the conduction velocity. 2. 4M NaCl evoked an irregular bursts of spikes which continued until washing out. Isotonic saline did not affect INA to subsequent applications of the hypertonic NaCl solution (P>0.05). 3. Local application of CGRP ($200{\mu}g$/ml) in deep dentinal cavity reduced the INA induced by 4M NaCl in $A{\delta}$-fiber units (P<0.01) and some units of those responded to CGRP during application. 4. Local application of SP ($100{\mu}g$/ml) in deep dentinal cavity reduced the INA induced by 4M NaCl in AS-fiber units (p<0.05), but increased the INA in C-fiber unit coincided with large reduction of the INA of $A{\delta}$-fiber units. 5. Monopolar electrical stimulation applied to the crown at intensities high enough to excite C-fibers (12V, 5ms, 10Hz, 10~30min) decreased the INA in $A{\delta}$-fiber units (P<0.01) and systemic pretreatment with phenoxybenzamine (3mg/kg, i.v.) enhanced this inhibitory effect (P<0.01). On the contrary, electrical stimulation increased the INA in C-fiber unit.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.52-59
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• 1998

The ZnS:Mn thin film electroluminescent(TFEL) devices fabricated by ALE system were investigated. Yellow-orange light emission was observed when the applied voltage exceeded 134 V and luminance increased sharply as the applied voltage increased. Luminance of 568 Cd/c $m^{2}$ was obtained under 1 KHz sinusoidal voltage wave application at the peak applied voltage of 230 V. The peak wavelength of the emissionwas 577 nm. The C-V, Q-V, $Q_{t}$ - $F_{p}$ , L- $Q_{cond}$, and V- $Q_{pol}$ have been measured under theapplication of the trapezoidal wave with its pulse width varying 0 to 75 .mu.sec. The phoshor and the insulator capacitance of the TFEL device under test were 24.3 nF/c $m^{2}$ and 9 nF/c $m^{2}$, respectively. It was observed that the threshold voltage changed from 137V to 100V as the pulse width varied from 0 to 75 .mu.sec. The L- $Q_{cond}$ characteristics showed that the light emission increased in proportion to the $Q_{cond}$. The luminance increased from 386 Cd/ $m^{2}$ to 607 Cd/ $m^{2}$ when the $Q^{+}$$_{cond}$ increased from 1.3 .mu.C/c $m^{2}$ to 2.3 .mu.C/c $m^{2}$. The V- $Q_{pol}$ characteristics showed that the V was inversely proportional to $Q_{pol}$./. th/ was inversely proportional to $Q_{pol}$./. pol/./.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.336-343
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• 2000

Purpose: Thallous-201 chloride produced at Korea Cancer Center Hospital(KCCH) is used in detecting cardiovascular disease and cancer. Thallium impurity can cause emesis, catharsis and nausea, so the presence of thallium and other metal impurities should be determined. According to USP and KP, their amounts must be less than 2 ppm in thallium and 5 ppm in total. In this study, the detection method of trace amounts of metal impurities in $[^{201}Tl]$TICI injection with polarography was optimized without environmental contamination. Materials and Methods: For the detection of metal impurities, Osteryoung Square Wave Stripping Voltammetry method was used in Bio-Analytical System (BAS) 50W polarograph. The voltammetry was composed of Dropping Mercury Electrode (DME) as a working electrode, Ag/AgCl as a reference electrode and Pt wire as a counter electrode. Square wave stripping method, which makes use of formation and deformation of amalgam, was adopted to determine the metal impurities, and pH 7 phosphate buffer was used as supporting electrolyte. Results: Tl, Cu and Pb in thallous-201 chloride solution were detected by scanning from 300 mV to -800 mV Calibration curves were made by using $TINO_3,\;CuSO_4\;and\;Pb(NO_3){_2}$ as standard solutions. Tl was confirmed at -450 mV peak potential and Cu at -50 mV Less than 2 ppm of Tl and Cu was detected and Pb was not detected in KCCH-produced thallous-201 chloride injection. Conclusion: Detection limit of thallium and copper is approximately 50 ppb with this method. As a result of this experiment, thallium and other metal impurities in thallous-201 chloride injection, produced at Korea Cancer Center Hospital, are in the regulation of USP and KP Polarograph could be applied for the determination of metal impurities in the quality control of radiopharmaceuticals conveniently without environmental contamination.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.257-265
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• 2020

Densities (ρ) for binary mixtures of ethanol (1) + diisopropyl ether (DIPE) or cyclohexane or alkane (C₆-C₉) (2) were measured at 298.15 K, 308.15 K and 318.15 K. The excess molar volume (V^E_m) of binary mixtures was calculated using ρ data and correlated with Redlich-Kister polynomial equation. The V^E_m values for binary mixtures of ethanol (1) + cyclohexane or n-alkane (C₆-C₉) (2) were positive, whereas for ethanol (1) + DIPE (2) these were negative. The magnitude of V^E_m values follows the order: cyclohexane > n-nonane > n-octane > n-heptane > n-hexane > DIPE. The V^E_m values have been interpreted qualitatively and also quantitatively in terms of Flory-Treszczanowicz-Benson (FTB) model and Prigogine-Flory-Patterson (PFP) theory. The values V^E_m predicted using FTB model agree well with experimental V^E_m values at all mole fractions. But the PFP theory describes well V^E_m data in ethanol-rich region (x₁ > 0.5) for all binary mixtures and is able to predict the sign of V^E_m vs x₁ curve for ethanol-lean region (x₁ < 0.5) except for ethanol (1) + nonane (2) mixtures.

• Molecules and Cells
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• v.39 no.4
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• pp.322-329
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• 2016

Voltage-gated $Ca^{2+}$ ($Ca_V$) channels are dynamically modulated by Gprotein-coupled receptors (GPCR). The $M_1$ muscarinic receptor stimulation is known to enhance $Ca_V2.3$ channel gating through the activation of protein kinase C (PKC). Here, we found that $M_1$ receptors also inhibit $Ca_V2.3$ currents when the channels are fully activated by PKC. In whole-cell configuration, the application of phorbol 12-myristate 13-acetate (PMA), a PKC activator, potentiated $Ca_V2.3$ currents by ~two-fold. After the PMA-induced potentiation, stimulation of $M_1$ receptors decreased the $Ca_V2.3$ currents by $52{\pm}8%$. We examined whether the depletion of phosphatidylinositol 4,5-bisphosphate ($PI(4,5)P_2$) is responsible for the muscarinic suppression of $Ca_V2.3$ currents by using two methods: the Danio rerio voltage-sensing phosphatase (Dr-VSP) system and the rapamycin-induced translocatable pseudojanin (PJ) system. First, dephosphorylation of $PI(4,5)P_2$ to phosphatidylinositol 4-phosphate (PI(4)P) by Dr-VSP significantly suppressed $Ca_V2.3$ currents, by $53{\pm}3%$. Next, dephosphorylation of both PI(4)P and $PI(4,5)P_2$ to PI by PJ translocation further decreased the current by up to $66{\pm}3%$. The results suggest that $Ca_V2.3$ currents are modulated by the $M_1$ receptor in a dual mode-that is, potentiation through the activation of PKC and suppression by the depletion of membrane $PI(4,5)P_2$. Our results also suggest that there is rapid turnover between PI(4)P and $PI(4,5)P_2$ in the plasma membrane.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.162-168
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• 2013

$Li_2MnO_3-LiMO_2$(M=Ni, Co, Mn) nano-composite is a promising cathode material for xEV application due to its high theoretic capacity. However high voltage operating system of $Li_2MnO_3-LiMO_2$(M=Ni, Co, Mn) has worked as a hurdle in its application because of the inherent demerits, such as cycle life degradation and gas evolution. In order to enhance cell performance of $Li_2MnO_3-LiMO_2$(M=Ni, Co, Mn)/graphite cell, we examined electrolyte mainly composed of FEC, fluroalkyl ether and $LiPF_6$ (F-based EL). F-based EL showed much better discharging retention ratio than 1.3 M $LiPF_6$ EC/EMC/DMC (3/4/3, v/v/v) (STD). Furthermore gas evolution, especially CO and $CO_2$ during $60^{\circ}C$ storage for 30 days was dramatically reduced owing to thermal stable SEI formation effect of F-based EL.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.159-163
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• 2013

A new Rhodamine B hydrazide hydrazone 1 has been synthesized and investigated as a colorimetric and fluorescent "off-on" sensor for the recognition of $Cu^{2+}$ in $CH_3CN/H_2O$ (1:1, v/v, HEPES 10 mM, pH = 7.0) solution. Sensor 1 displayed highly selective, sensitive and rapid recognition behavior toward $Cu^{2+}$ among a range of biologically and environmentally important metal ions. Sensor 1 bind $Cu^{2+}$ via a 1:1 stoichiometry with an association constant of $1.92{\times}10^6\;M^{-1}$, and the detection limit is evaluated to be $7.96{\times}10^{-8}\;M$. The $Cu^{2+}$ recognition event is reversible and is barely interfered by other coexisting metal ions.