• ETRI Journal
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• v.30 no.4
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• pp.506-515
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• 2008

The H.264/AVC standard has adopted new coding tools such as intra-prediction, variable block size, motion estimation with quarter-pixel-accuracy, loop filter, and so on. The adoption of these tools enables an H.264/AVC-coded bitstream to have more information than was possible with previous standards. In this paper, we propose an effective spatial error concealment method with low complexity in H.264/AVC intra-frame. From information included in an H.264/AVC-coded bitstream, we use prediction modes of intra-blocks to recover a damaged block. This is because the prediction direction in each prediction mode is highly correlated to the edge direction. We first estimate the edge direction of a damaged block using the prediction modes of the intra-blocks adjacent to a damaged block and classify the area inside the damaged block into edge and flat areas. Our method then recovers pixel values in the edge area using edge-directed interpolation, and recovers pixel values in the flat area using weighted interpolation. Simulation results show that the proposed method yields better video quality than conventional approaches.

• Nuclear Engineering and Technology
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• v.41 no.2
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• pp.149-154
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• 2009

The microstructure, the corrosion behavior and the oxide properties were examined for Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr (HANA-4) alloys which were subjected to two different final annealing temperatures: $470^{\circ}C$ and $570^{\circ}C$. HANA-4 was shown to have $\ss$-enriched phase with a bcc crystal structure and Zr(Nb,Fe,Cr)$_2$ with a hcp crystal structure with $\ss$-enriched phase being more frequently observed compared with Zr(Nb,Fe,Cr)$_2$. The corrosion rate of HANA-4 was increased with an increase of the final annealing temperature in the PWR-simulating loop, $360^{\circ}C$ pure water and $400^{\circ}C$ steam conditions, which was correlated well with a reduction in the size of the columnar grains in the oxide/metal interface region. The oxide growth rate of HANA-4 was considerably affected by the alloy microstructure determined by the final annealing temperature.

• Journal of Information Technology Services
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• v.14 no.1
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• pp.99-113
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• 2015

Adaptive bitrate (ABR) streaming technology has become an important and prevalent feature in many multimedia delivery systems, with content providers such as Netflix and Amazon using ABR streaming to increase bandwidth efficiency and provide the maximum user experience when channel conditions are not ideal. Where such systems could see improvement is in the delivery of live video with a closed loop cognitive control of video encoding. In this paper, we present streaming camera system which provides spatially and temporally adaptive video streams, learning the user's preferences in order to make intelligent scaling decisions. The system employs a hardware based H.264/AVC encoder for video compression. The encoding parameters can be configured by the user or by the cognitive system on behalf of the user when the bandwidth changes. A cognitive video client developed in this study learns the user's preferences (i.e. video size over frame rate) over time and intelligently adapts encoding parameters when the channel conditions change. It has been demonstrated that the cognitive decision system developed has the ability to control video bandwidth by altering the spatial and temporal resolution, as well as the ability to make scaling decisions

• Nuclear Engineering and Technology
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• v.36 no.6
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• pp.540-548
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• 2004

Check valve failure is one of the worst problems in nuclear power plants. Recently, many researches have been based on new technology using accelerometers and ultrasonic and magnetic flux detection have been carried out. Here, we have suggested a method that uses acoustic emission sensors for detecting the failures of check valves through measuring and analyzing backward leakage flow, a system that works without disassembling the check valve. For validating the suggested acoustic emission sensor methodology, we designed a hydraulic test loop with a check valve. We have assumed in this study that check valve failure is caused by disk wear or by the insertion of a foreign object. In addition, we have developed diagnostic algorithms by using a neural network model to identify the type and size of the failure in the check valve. Our results show that the proposed diagnostic algorithm with acoustic emission sensors is a good solution for identifying check valve failure without necessitating any disassembly work.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.543-550
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• 2003

Thin paper proposes a new three-phase rectifier that actively shapes the input current sinusoidal by means of two rectifier bridges, each followed by a dc-dc boost converter. The proposed approach draws sinusoidal input current at unity power factor and has output voltage regulation capability The size and weight of magnetic material Is reduced by Incorporating a low KVA three-phase autotransformer and by directly connecting the dc outputs each other without using low frequency interphase transformer(IPT). The operation principle is described along with simple control method, and experimental results on a 1.5KW prototype are provided.

• Journal of Marine Life Science
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• v.4 no.2
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• pp.53-62
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• 2019

Heterotrophic bacteria are a major member of the microbial loop in the marine ecosystem and play an important role in the biogeochemical cycle decomposing organic matter. Therefore study of bacterial variation is important to understand the material cycle and energy flow of marine ecosystems. We investigated the monthly variations of bacteria and environmental factors in the Youngsan River estuary, and the correlation between bacteria and phytoplankton biomass (chlorophyll-a) including size-structure. As a result, bacteria of the Youngsan River estuary were higher in the surface than in the bottom layer, and higher in the summer than in winter. And the closer to the dike, the abundance increased, and it increased to the peaks in August, September, and June 2019 at the station closest to the dike. The chlorophyll-a also increases at the stations and time when the bacterial abundance was high and they correlates positively displaying no difference between size fractions. The results indicate that organic matter derived from phytoplankton has an effect on bacterial variation but no size-dependent effects. In addition, the seasonal pattern of bacteria increasing in proportion to the water temperature suggests the effect of water temperature on the growth of bacteria. No association of bacterial abundance variation with nutrient supply due to freshwater input was observed. In this study, dissolved oxygen was depleted and hypoxia was observed for a short time when a strong stratification was not developed. This may be resulted from the supply of organic matter from phytoplankton and the consumption of oxygen due to bacterial decomposition.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.54-68
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• 1985

It is desirable to collect the solar thermal energy at relatively high temperature in order to minimize the size of thermal storage system and to enlarge the scope of solar thermal energy utilization. So far the concentrating solar collector has been developed to collect solar thermal energy at relatively high temperature, but it has some difficulties in maintaining the volumetric body of solar collector for long term utilization. On the other hand, the flat-plate solar collector has been developed to collect the solar thermal energy at low temperature, and it has advantages in maintaining the system for long term utilization, since it's thickness is thin and not volumetric. In this study, to develop a solar collector that has both advantages of collecting solar thermal energy at high temperature and fixing conveniently the collector system for long term period, a cylindrical parabolic concentrating solar collector was designed, which has two rows of parabolic reflectors and thin thickness such as the flat-plate solar collector, maintaining the optical form of concentrating solar collector. The characteristics of the concentrating parabolic solar collector newly designed was analysed and the results are summarized as follows; 1. The temperature of the air enclosed in solar collector was all the same as $50^{\circ}C$ in both cases of the open and closed loop, and when the heat transfer fluid was not circulated in tubular absorber, the maximum surface temperature of the absorber was $118-120^{\circ}C$, this results suggested that the heat transfer fluid could be heated up to $118^{\circ}C$. 2. In case of longitudinal installation of the solar collector, the temperature difference of heat transfer fluid between inlet and outlet was $4^{\circ}-6^{\circ}C$ at the flow rate of $110-130{\ell}/hr$, and the collected solar energy per unit area of collector was $300-465W/m^2$. 3. The collected solar energy per unit area for 7 hours was 1960 Kcal/$m^2$ for the open loop and 220 Kcal/$m^2$ for the closed loop. Therefore it is necessary to combine the open and closed loop of solar collectors to improve the thermal efficiency of solar collector. 4. The thermal efficiency of the solar collector (C.P.C.S.C.) was proportional to the density of solar radiation, indicating the maximum thermal efficiency ${\eta}_{max}=58%$ with longitudinal installation and ${\eta}_{max}=45%$ with lateral installation. 5. The thermal efficiency of the solar collector (C.P.C.S.C.) was increased in accordance with the increase of flow rate of heat transfer fluid, presenting the flow rate of $110{\ell}/hr$ was the value of turning point of the increasing rate of the collector efficiency, therefore the flow rate of $110{\ell}/hr$ was considered as optimum value for the test of the solar collector (C.P.C.S.C.) performance when the heat transfer fluid is a liquid. 6. In both cases of longitudinal and lateral installation of the solar collector (C.P.C.S.C.), the thermal efficiency was decreased linearly with an increase in the value of the term ($T_m-T_a$)/Ic and the increasing rate of the thermal efficiency was not effected by the installation method of solar collector.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.16-21
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• 2017

In this paper, a Small-sized and planer resonator design of Magnetic Resonance - Wireless Power Transfer(MR-WPT) were proposed for practical applications of mobile devices, such as a laptop, a smart-phone and a tablet pc. The proposed MR-WPT system were based on four coil MR-WPT and designed as a transmitter part (Tx) and a receiver part (Rx) both are the same shape with the same loop and resonator. There are four different spiral coil type of resonators with variable of line length, width, gap and turns in $50mm{\times}50mm$ size. The both of top and bottom side of substrate(acrylic; ${\varepsilon}_r=2.56$, tan ${\delta}=0.008$) ere used to generate high inductance and capacitance in limited small volume. Loops were designed on the same plane of resonator to reduce their volume, and there are three different size. The proposed MR-WPT system were fabricated with two acrylic substrate plane of Tx and Rx each, the Rx and Tx loops and resonators were fabricated of copper sheets. There are 12 combinations of 3 loops and 4 resonators, each combination were measured to calculate transfer efficiency and resonance frequency in transfer distance from 1cm to 5cm. The measured results, the highest transfer efficiency was about 70%, and average transfer efficiency was 40%, on the resonance frequency was about 6.78 MHz, which is standard band by A4WP. We proposed small-sized and planer resonator of MR-WPT and showed possibility of mobile applications for small devices.

• Journal of Gastric Cancer
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• v.4 no.4
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• pp.252-256
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• 2004

Purpose: Anastomosis site stricture is a common complication after a total gastrectomy. End-to-end anastomosis (EEA) stapler devices are preferred to a hand-sewn esophagojejunostomy these days. However, stapling devices have been reported not to reduce the incidence of esophagojejunostomy site stricture considerably. Materials and Methods: From Sep. 1998 to Dec. 2000, at Korea Gastic Cancer Center, Seoul Paik Hospital, Inje University, we experienced 228 total gastrectomies in which EEA stapling devices had been used. We investigated the correlation of the stricture with the size of the EEA stapling device, the type of esophagojejunal reconstruction, reflux esophagitis, and duration of stricture development. Results: Among the 228 cases, as far as the patient's age was concerned, the 7th decade was the most common 64 cases, followed by the 5th decades. The Male-to-female ratio was 2.3：1. A loop esophagojejunostomy was used in 223 cases, and the Roux-en-Y method was used in 5 cases. The 32 patients with anastomosis site stricture were patients with loop esophagojejunal anastomosis. Anastomosis site stricture occurred in $14\%$ (32/228) of the total gastrectomy cases, in$15.9\%$ (11/69) of the total gastrectomies involving stapler devices with a 25-mm diameter, and in $13.2\%$ (21/159) of the total gastrectomies involving staper devices with a 28-mm diameter. There was no correlation between the incidence of stricture and EEA- stapling device size (P>0.05). Reflux esophagitis occurred in 56 of the 228 cases, with 7 of those 56 cases ($12.5\%$) and 25 of the remaining 172 cases ($14.5\%$) having strictures. There was no considerable difference in the stricture incidence rate according to the presence of reflux esophagitis (P>0.05). The onset of stricture development, occurred within 6 months in 16 cases, including 4 cases of reflux esophagitis, between 7 and 18 months in 14 cases, including 3 cases of reflux eshophagitis, and after 19 months in 2 cases. Conclusion: An esophagojejunostomy site stricture after a total gastrectomy was not correlated with the esophagojejunal reconstruction type, the size of the stapling device, or the presence of reflux esophagitis. General anastomosis technical factors (e.g., adequate blood supply, tension-free manner, adequate hemostasis) may be more important to prevent anastomosis site stricture after an esophagojejunostomy during a total gastrectomy.

• Advances in pediatric surgery
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• v.3 no.2
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• pp.98-107
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• 1997

To determine whether bile juice exclusion can prevent the mucosal damage, and Insulin-like growth factor-I can promote mucosal regeneration in ischemia-reperfusion injury of the bowel, 39 weanling rats with 10 cm of Thiry-Vella loop were studied. Animal groups were; Control, BL(common bile duct ligation), IGF{insulin-like growth factor-I(IGF-I) infusion} and IGF-BL(combined treatment). IGF-I(1.5 mg/kg/day) was continuously delivered through a subcutaneously implanted miniosmotic pump. After 15 minutes of superior mesenteric artery clamping, a tissue specimen(P) was taken after 30 minutes of reperfusion. Intestinal continuity was restored to allow oral feeding. A specimen of main tract(M) and another of the Thiry-Vella loop(T) were collected for histomorphometry after 48 hours of reperfusion and free feeding. Villus size ratio(VSR), crypt depth(CD), crypt-depth/villus-height ratio(CVR) and injury score(IS) were measured in 15 consecutive villi. The postoperative mortalities of bile duct ligation groups(BL and IGF-BL) were higher than those of other groups. In control group, VSR of M was lower(P<0.05) than P or T, but not in the other groups. VSR of M in control was lower than those in other groups. CD of T in control, IGF and IGF-BL group were higher than those of M. CD of M and T showed gradual increments from control, IGF and IGF-BL group, respectively. CVR of M and T in IGF group were higher than those in control. CVR in IGF-BL group, T was higher than M, and M was higher than P. About IS, M of BL($20.1{\pm}2.5$) and IGF-BL($20.9{\pm}3.3$) groups were significantly lower than that of control($32.4{\pm}2.5$). These results suggest that the exclusion of bile juice reduces the severity of the reperfusion injury of the mucosa, by inability to activate pancreatic enzymes and IGF-I stimulates mucosal regeneration in injured bowel, and the effect is potentiated by bile juice exclusion.