• Magazine of the Korean Society of Agricultural Engineers
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• v.9 no.2
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• pp.1301-1305
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• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.443-447
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• 2009

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_{2}Te_{3}$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $5{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_{2}Te_{3}$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_{2}Te_{3}$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3 ${\mu}m$ is obtained at the temperature difference of 45 K.

• Journal of IKEEE
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• v.14 no.2
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• pp.90-97
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• 2010

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device and DTMOS Error Amplifier is presented in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. Dynamic Threshold voltage CMOS(DT-CMOS) with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an DT-CMOS error amplifier and a comparator circuit as a block. the proposed DT-CMOS Error Amplifier has 72dB DC gain and 83.5deg phase margin. also Error Amplifier that use DTMOS more than CMOS showed power consumption decrease of about 30%. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device is achieved the high efficiency near 96% at 100mA output current. And DC-DC converter is designed with Low Drop Out regulator(LDO regulator) in stand-by mode which fewer than 1mA for high efficiency.

• Polymer(Korea)
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• v.37 no.4
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• pp.431-436
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• 2013

Polycarbonate (PC) films have been irradiated with various kinds of ions according to energy and dose. Change of the optical transmittance and chemical characteristics were confirmed by UV-VIS and FTIR (ATR) spectroscopy respectively. These UV-A block in 400 nm was variable from 10 to 100% according to energy and doses. Surface electrical resistance of PC film irradiated by ion beam was $10^6-10^{13}{\Omega}/cm^2$, which reveal variation of conduction. Contact angle of film irradiated by ion beam was decreased than the pristine film. Polymer surface morphology was examined by means of atomic force microscopy (AFM). As expected, degradation of polymer film was higher after irradiation with heavier Xe ions but the roughness in the polymer surface morphology were more pronounced for Ar ions. This observed effect can be explained by stronger compaction of polymer surface layer in the case of Xe irradiation, connected with a reduction of free volume available.

• Journal of The Korean Dental Society of Anesthesiology
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• v.3 no.1 s.4
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• pp.6-9
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• 2003

Background: The use of neurolytic agents to control neuropathic pain has been described from the last century Phenol and ethyl alcohol have been widely used as neurolytic agents, however, their neurolytic effect is variable in efficacy and duration of action, and infrequently accompanied with grave complications. It has been found that 5% lidocaine causes irreversible conduction blockade in animal studies. The goal of this study was to evaluate the neurolytic effect of 5%o lidocaine on various neuropathic pain syndromes for prolonged analgesia. Methods: Twenty-five patients with a diagnosis of neuropathic pain including trigeminal neuralgia (n = 7), postherpetic neuralgia (n = 10), and postsurgical neuralgia (n = 8) were selected after failure of routine therapeutic regimens. After performing a diagnostic nerve block with 1% lidocaine and 5% lidocaine was injected. The patients were followed for 6 months. Visual analog scale (VAS) scores and side effects were recorded for each patients. Results: A significant decrease in pain scores after neurolytic blockade with 5% lidocaine was seen in all of three pain groups. All the patients reported immediate and prolonged pain relief lasting from 4 weeks to 6 months. None of patients exhibited any appreciable side effects or complications. Conclusions: We suggest that 5% lidocaine may be used safely and effectively for the purpose of prolonged analgesia in selected patients with intractable neuropathic pain syndromes.

• Journal of Chest Surgery
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• v.18 no.4
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• pp.623-634
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• 1985

One of the most widely recognized problems in patients with TGA [transposition of the great arteries] after the Senning operation is the occurrence of arrhythmias. From June 1982 through October 1984, 22 patients, 11 with "simple" and 11 with "complex" TGA, underwent correction of TGA by a modification of the Senning operation designed to avoid dysrhythmias. 16 were males and 6 females, with ages ranging from 3 months to 27 months. [mean age 10.8 months] 7 patients [31.8%], 1 with simple TCA and 6 with complex TGA, died in the early post-operative period. The operative mortality was 9.1% in "simple" TGA, and 54.9% in "complex" TGA. There were 4 late deaths but only one of these patients died of a dysrhythmia as a possible factor. The standard ECG [Electrocardiography] checked preoperatively showed sinus rhythm in 17 [77.3%], 1 AV block in 5 [22.7%]. In 22 patients studied postoperative 1st day, the incidence of arrhythmias was 63.6%, with significant incidence compared with preoperative study. [P<0.05]. But, in 15 patients studied postoperatively at intervals from 1 month to 26 months, the incidence of arrhythmias was 26.7%, with no significant incidence compared with preoperative study [P>0.1]. Our results indicate that a modified Senning operation may reduce the frequency of surgically induced arrhythmias. The mean frontal plane P-wave axis also revealed significant deviation to the right side [P<0.05], compared with preoperative study. These findings raise the possibility that what has been called sinus rhythm postoperatively may have a different origin and conduction sequence from normal. But the rhythm seems to be functionally similar.rhythm seems to be functionally similar.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.265-271
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• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• Clinical and Experimental Pediatrics
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• v.46 no.2
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• pp.154-161
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• 2003

Purpose : The prognosis of patients with corrected transposition of the great arteries(C-TGA) is variably affected by associated intracardiac defects, systemic right ventricular function, tricuspid valve competence, and conduction disturbances. This study aims to evaluate the importance of those factors at mid-term follow-up. Methods : Medical records of 94 patients(males 58, females 36; mean age at last follow-up, $12{\pm}9$ years; mean follow-up duration, $9{\pm}6.4$ years) diagnosed between January 1980 and May 2002 at Seoul National University Children's Hospital were studied retrospectively. Results : Among 94 patients, operations were performed in 72 patients(classic operations in 55; double switch operations in 17). Among prognostic factors including associated intracardiac anomalies(at least moderately severe tricuspid insufficiency(TI), ventricular septal defect, pulmonary stenosis and pulmonary atresia), intracardiac operation and complete atrioventricular block, TI was the only significant factor for death(P=0.001), and in turn, Ebstein anomaly and high grade atrioventricular block predicted TI. 20-year survival without TI was 77%, but only 35% with TI(P=0.0002); excluding perioperative death, the 20-year survival rates with and without TI were 48% and 87% respectively(P=0.008). There was no statistical difference in 20-year survival rate or association with TI between classic and double switch operation. Conclusion : TI was the major prognostic factor for C-TGA and was associated with Ebstein anomaly and high grade atrioventricular block at mid-term follow-up. Long-term follow-up is required to evaluate other factors, including double switch operations and associated intracardiac defects more exactly.

• Journal of IKEEE
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• v.12 no.3
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• pp.176-183
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• 2008

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device is proposed in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. DTMOS with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an error amplifier and a comparator circuit as a block. The Saw-tooth generator is made to have 1.2 MHz oscillation frequency and full range of output swing from ground to supply voltage(VDD:3.3V). The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device, achieved the high efficiency near 95% at 100mA output current. And DC-DC converter is designed with LDO in stand-by mode which fewer than 1mA for high efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.103-112
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• 1991

In this study, a numerical model was established and applied to simulate the steady-state groundwater and heat flow in an isotropic, heterogeneous, three dimensional aquifer system with uniform thermal properties and no change of state. This model was developed as an aid in screening large groundwater-flow systems as prospects for underground waste storage. Driving forces on the system are external hydrologic conditions of recharge from precipitation and fixed hydraulic head boundaries. Heat flux includes geothermal heat-flow, conduction to the land surface, advection from recharge, and advection to or from fixed-head boundaries. The model uses an iterative procedure that alternately solves the groundwater-flow and heat-flow equations, updating advective flux after solution of the groundwater-flow equation, and updating hydraulic conductivity after solution of the heat-flow equation. Dierect solution is used for each equation. Travel time is determined by particle tracking through the modeled space. Velocities within blocks are linear interpolations of velocities at block faces. Applying this model to the groundwater-flow system located in Jigyung-ri. Songla-myun, Youngil-gun. Kyungsangbuk-do, the groundwater-flow system including distribution of head, temperature and travel time and flow line, is analyzed.