• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.791-799
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• 2016

This paper presents the design of reconfigurable frequency selective surfaces for X-band bandpass operation with improved isolation. The proposed reconfigurable FSS is composed of a four-legged loaded element, a inductive stub and a bias grid. The PIN diode is located between the four-legged loaded element and the stub, which can control the frequency response of reconfigurable FSS by ON/OFF state. By adjusting the length of the stub, the desired bandpass frequency and the improved isolation between ON and OFF state can be obtained. For validation of simulated results, we have carried out transmission characteristic measurements using rectangular waveguide of WR-90. The measured results are in good agreements with the simulated results.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.772-777
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• 2012

Factors acting on the deactivation of $V_2O_5/TiO_2$ catalysts were investigated in the selective catalytic reduction(SCR) process for long term operation. The activity of $V_2O_5/TiO_2$ catalysts was decreased rapidly after 8 months from the starting of operation in the selective catalytic reaction processes. From ICP-AES analysis, the deactivation of the used catalysts could be caused from the calcium component included in urea solution as a reducing agent. It was found from the $NH_3$-TPD experiments that the strong basic element like Ca component drastically affected the acidity of the $V_2O_5/TiO_2$ catalyst. The results gave an explanation on the reason why the component of Ca, even though its concentration is very low, could lead to the deactivation of $V_2O_5/TiO_2$ catalyst in the selective catalytic reaction processes.

• Journal of Chest Surgery
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• v.11 no.3
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• pp.342-347
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• 1978

A 8 year old male was admitted to the Department of Thoracic Surgery, Korea University Hospital on June 22, 1978. The chief complaints were cyanosis and exertional dyspnea since at birth. EKG shows BVH and dextrocardia, phonocardiogram revealed the accentuation of second heart sound in aortic area. Echocardiogram from the left ventricle to the base of the heart, there is a discontinuity between the ventricular septum and the anterior aortic margin with a large aortic root & aortic overriding. His cardiac catheterization data and cardiac angiogram shows situs inversus totalis, dextrocardia, right aortic arch, large ventricular septal defect etc., and finally diagnosed Truncus Arteriosus. Edwards type IV with retrograde aortogram and selective bronchial angiogram. This is the first operative case reported as Rastelli operation for Truncus Arteriosus type IV in the literatures in Korea. Authors have experienced I case of Truncus Arteriosus, Edward type IV and Rastelli operation with Dacron Arterial Conduit Graft under cardiopulmonary bypass on July 3, 1978. The procedures were as follows; 2] Cardiopulmonary bypass: Origin of bronchial arteries excised from descending aorta bilaterally; defects in aorta closed. 2] Horizontal incision made high in right ventricle. 2] Ventricular septal defect [Kirklin type I+II] closed with Teflon patch. 4] Bifurcated dacron arterial graft with pericardial monocusp sutured to the bilateral pulmonary arteries. [Diameter 9 mm: Length 7 cm]. 5] Proximal end of the conduit graft anastomosed to right ventricle. [Diameter 19 mm: Length 5 cm]..Total perfusion time was 220 min. The result of operation was poor due to anastomotic leakage and increased pulmonary vascular resistance resulting acute right heart failure. The patient was died on the operation table. Literatures were briefly reviewed.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.631-636
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• 2018

This paper proposed an optimal operation strategy for a hybrid energy storage system (HESS) with a lithium-ion battery and lead-acid battery for mild hybrid electric vehicles (mild HEVs). The proposed mild HEV system is targeted to mount the electric motor and the battery to a conventional internal combustion engine vehicle. Because the proposed mild HEV includes the motor and energy storage device of small capacity, the system focuses on low system cost and small size. To overcome these limitations, it is necessary to use a lead acid battery which is used for a vehicle. Thus, it is possible to use more energy using HESS with a lithium battery and a lead storage battery. The HESS, which combines the lithium-ion battery and the secondary battery in parallel, can achieve better performance by using the two types of energy storage systems with different characteristics. However, the system requires an operation strategy because accurate and selective control of the batteries for each situation is necessary. In this paper, an optimal operation strategy is proposed considering characteristics of each energy storage system, state-of-charge (SOC), bidirectional converters, the desired output power, and driving conditions in the mild HEV system. The performance of the proposed system is evaluated through several case studies with respect to energy capacity, SOC, battery characteristic, and system efficiency.

• Archives of Pharmacal Research
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• v.7 no.2
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• pp.101-107
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• 1984

The concentrations of metabolites of low molecular weights (90 to 310 amu) present in rat urine were determined by field ionization mass spectrometry. Three groups of rats were examined; intact controls, sham-operated rats and rats with selective lesions in their hypothalamus. The latter lesions are shown to induce characteristic aberrations in the metabolic profile, demonstrable five weeks after treatment, which are distinct from those induced by a sham operation.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.33-36
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• 1992

In this paper we propose the impulse noise-robust Wiener filter based on a combination of Wiener and modified trimmed mean(MTM) filters. The robust Wiener filter uses the trimming operation of the MTM filter to replace the outliers with the median within the window and the new set of samples which can be considered as the random process with same mean are inputted into the following Wiener filter. We show that the robust Wiener filter is effective in frequency selective filtering of nonstationary signals while preserving signal edges with the rejection of impulse noise.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.706-709
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• 2003

We made an optimization effort on driving waveforms for the Quantized Memory Addressing (QMA) in selective write mode of operation. It was necessary to add long ramp type erase pulses after the total write pulse and the sustain period to obtain stable intermediate luminance discharges. Furthermore, fast rising ramp type total write as well as two step addressing scheme were adopted for better discharge stability.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.454-458
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• 2004

A study of the POSE (predispersed solvent extraction) for succinic acid by colloidalliq­uid aphrons was conducted. The organic phase contaning TOA (tri-n-octylamine) and 1-octanol permits a selective extraction of succinic acid from its aqueous solution. There was no difference of the extractability of POSE and that of conventional mixer-settler type extraction. Taking into account the no mechanical mixing in POSE, it was concluded that the POSE process is more adaptive than the conventional mixer-settler type extraction process. From mass transfer analysis at the various concentration of TOA in counter-current continuous operation, the concentration of TOA had no influence on the mass transfer coefficient. The loading values in continuous POSE were almost same as those in batch operation.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.3-11
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• 1984

Prosthetic valve replacement has resulted in marked improvement in the functional status of many patients with valvular heart disease. But valve failure from various causes has necessitated re-replacement of prosthetic valve in some of these patients. This selective group of patients has many inherent problems. This report presents our experience with seven patients who received re-replacement of prosthetic valve in the Seoul National University Hospital from 1981, to 1983. The patients included one woman and six men in the range of 9 and 49 years old. As the first valve operations, there were five MVR using tissue valves, one DVR [Bjork-Shiley and Ionescu-Shiley valve] and one case of modified Bentall operation with composite graft [Ionescu-Shiley valve]. Reoperations on prosthetic valve failure were performed 17 to 54 months after the first operation [mean 34 months]. Amon8 seven patients, there were two cases of prosthetic valve endocarditis and five cases of primary tissue failure. Gross calcification of the xenograft was found in two children with Ionescu-Shiley valve. All except one had relatively successful operative results. The unsuccessful one died intraoperatively from low output syndrome.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.855-859
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• 2007

Hydrogen as an energy carrier in fuel cell offers perhaps the largest potential benefits of reduced emissions of pollutants and greenhouse gases. The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. Reduction of carbon monoxide to an acceptable level of 10ppm involves high temperature and low temperature water gas shift (WGS), followed by selective oxidation of residual carbon monoxide. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 5000 ppm. In the water gas shift operation, gas emerges from the reformer is taken through a high temperature shift (HTS) catalyst to reduce the CO concentration to about $2{\sim}4%$ followed to about 5000 ppm via a low temperature shift (LTS) catalyst.