• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.617-624
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• 2003

This paper proposes a modified DCPC (Distributed Constrained Power Control, M-DCPC) algorithm that can improve the performance of a CDMA power control system. The control performance of the proposed method is verified using two performance measures : the SIR response of each mobile and the outage probability in a cell. As regards the SIR response, in simulations, the M-DCPC algorithm has shown a faster convergence and lower overshoot in transient time than the other power control algorithms when the desired SIR value was varying. For the outage probability. M-DCPC converged to a fixed outage rate faster than CSOPC while also maintaining the system capacity to make as high a connection as CSOPC. In particular, when the desired SIR was varying, CSOPC showed an abrupt outage probability increase during the desired SIR Increase, yet M-DCPC was unaffected.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.123-130
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• 2019

Chelatase catalyzes the insertion of divalent metal into tetrapyrrole and plays a key role in the biosynthesis of metallated tetrapyrroles, such as cobalamin, siroheme, heme, and chlorophyll. SirB is a sirohydrochlorin (SHC) chelatase that generates cobalt-SHC or iron-SHC by inserting cobalt or iron into the center of sirohydrochlorin tetrapyrrole. To provide structural insights into the metal-binding and SHC-recognition mechanisms of SirB, we determined the crystal structure of SirB from Bacillus subtilis subsp. spizizenii (bssSirB) in complex with cobalt ions. bssSirB forms a monomeric ${\alpha}/{\beta}$ structure that consists of two domains, an N-terminal domain (NTD) and a C-terminal domain (CTD). The NTD and CTD of bssSirB adopt similar structures with a four-stranded ${\beta}-sheet$ that is decorated by ${\alpha}-helices$. bssSirB presents a highly conserved cavity that is generated between the NTD and CTD and interacts with a cobalt ion on top of the cavity using two histidine residues of the NTD. Moreover, our comparative structural analysis suggests that bssSirB would accommodate an SHC molecule into the interdomain cavity. Based on these structural findings, we propose that the cavity of bssSirB functions as the active site where cobalt insertion into SHC occurs.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.729-741
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• 2011

Wind speeds have long been estimated from C-band VV-polarized SAR data by using the CMOD algorithms such as CMOD4, CMOD5, and CMOD_IFR2. Some SAR data with HH-polarization without any observations in VV-polarization mode should be converted to VV-polarized value in order to use the previous algorithms based on VV-polarized observation. To satisfy the necessity of polarization ratio (PR) for the conversion, we retrieved the conversion parameter from full-polarized SIR-C SAR image off the east coast of Korea. The polarization ratio for SIR-C SAR data was estimated to 0.47. To assess the accuracy of the polarization ratio coefficient, pseudo VV-polarized normalized radar cross section (NRCS) values were calculated and compared with the original VV-polarized ones. As a result, the estimated psudo values showed a good agreement with the original VV-polarized data with an root mean square error by 0.99 dB. We applied the psudo NRCS to the estimation of wind speeds based on the CMOD wind models. Comparison of the retrieved wind field with the ECMWF and NCEP/NCAR reanalysis wind data showed relatively small rms errors of 1.88 and 1.91 m/s, respectively. SIR-C HH-polarized SAR wind retrievals met the requirement of the scatterometer winds in overall. However, the polarization ratio coefficient revealed dependence on NRCS value, wind speed, and incident angle.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.46-51
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• 2006

This paper reports on the effects of silicone oils, used as processing agents, on the recovery of hydrophobicity of silicone rubber. The recovery of hydrophobicity was evaluated by the measuring the contact angle, the surface electrical resistance and SEM. Here, we formed artificial contamination on the surface of samples, which scratched by sand papers and alumina powders. There was small recovery of hydrophobicity on the surface of SIR-A that silicone oil was not added. In both oil-added samples, SIR-B and SIR-C, recovery of hydrophobicity was achieved greatly. The surface of SIR-C showed that a lot of silicone oil was observed due to migration of oil, relatively in comparison with SIR-B. The tendency of recovery of hydrophobicity expressed by contact angle was in a good agreement with electrical property as determined by surface resistivity.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1560-1562
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• 2000

The paper reports on a study of the influence of the silicone oils on the tracking and erosion resistance and hydrophobicity of SIR. Two silicone oils(A, B) having different chemical structure were selected in consideration of goof hydrophobicity and processability. Tracking and erosion resistance of SIR was investigated by the rotating wheel dip test (RWDT). In this test tracking and erosion areas due to glow and partial arc discharges cause an increase in the leakage current with an increase in time. Leakage current of SIR was decreased with increasing ratio of oil A/B. SIR was exposed to corona discharges in air and the specimens were analyzed with contact angle. It was observed that the contact angle of SIR was increased gradually in time. The recovery of hydrophobicity was increased with increasing ratio of oil A/B.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.78-85
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• 1998

The design method of a temperature stable bandpass filter using dielectric coaxial resonators of with two dielectric ceramics with opposite signs of temperature coefficient of dielectric constant (${\tau}_{\epsilon}$) to compensate for each other in this method. $MgTiO_3$(${\tau}_{\epsilon}$=+99 ppm/${\circ}C$) as a positive ${\tau}_{\epsilon}$ material and Ba($Zn_{1/3}Nb_{2/3}$)$O_3$(${\tau}_{\epsilon}$=-77ppm/${\circ}C$) as a negative material were selected. The length of a SIR for the temperature stability was calculated according to the design method and the susceptance slope parameter of the SIR was obtained. A temperature stable bandpass filter using dielectric SIR's was designed, simulated and fabricated. The center frequency of this filter was 915 MHz and the pass bandwidth was 20 MHz. Temperature properties of this bandpass filter by simulations were compared with the measured results of the bandpass filter fabricated.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.158-164
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• 1999

This paper investigated and evaluated the NASA's Shuttle Imaging Radar-C (SIR-C) multiple frequency SAR data for differential backscattering effects of microwave from the surface geological materials overlying the skarn type mineralization. Although an integrated approach in mineral exploration is more cost effective and is well in use, there are still many technical and scientific issues to be further investigated and researched. In this study we have reprocessed several sets of previously surveyed exploration data and experimented with fuzzy logic digital fusion of the preprocessed data with respect to chosen exploration targets. Among the numerous fuzzy logic operators, which are currently available for a data driven integrated exploration strategy, we used varying combinations of fuzzy MIN, fuzzy MAX, and fuzzy SUM operators along with Gamma operator for fusion of exploration data, including the contact metamorphic zone information. The final exploration target tested was a skarn type W-Mo-F mineralization in the study area. The fuzzy logic derived mineral potential anomaly almost exactly matched the differential backscattering anomalies on the C-band and L-band SIR_C data when overlaid on each other. Although this high degree of correlation between these two data sets is remarkable, the differential backscattering anomaly over the skarn type W-Mo-F mineralization in the study area requires further investigation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.326-332
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• 1999

In this paper, we designed and fabricated High-Tc Superconducting (HTS) microstrip bandpass filters using Stepped Impedance Resonators(SIR) and studied on their characteristics. The $high-T_c$ superconducting $Y_1Ba_2Cu_3O_{7-x}$ epitaxial films were deposited by Pulse Laser Deposition (PLD) system on MgO. The fabricated filters were designed so as to operate in Ku band with central frequency 17.25 GHz, bandwidth 2.896% and ripple 0.01 dB. These filters were composed of parallel coupled microstrip SIR of which impedance ratio (K) are 0.5, 1.5. In the measured response, HTS filters had showed insertion loss below -0.5 dB. For comparison with normal conducting filter, we fabricated the Au counterpart that consists of the resonators as K=1.5 in the same dimension and measured performance of the Au filter. In comparison, HTS filter designed optimally got superior response to gold conterpart.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.219-227
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• 2006

In this paper, we propose a packet scheduling algorithm to maximize the required total price of the systems that is applied with a different traffic pricing criterion by the mobile service operator according to different kinds of the services. The proposed algorithm adopts a particular estimation method in scheduling using the value of pricing function, which is based on the required services and the value of SIR(signal to interference ratio) that indicate the channel condition of each user. We compare Max C/I, proportional fairness and round robin algorithm with the proposed algorithm on HSDPA in order to analyze the performance. The result shows that the proposed algorithm satisfies higher throughput and provides maximum the mobile service provider's revenue.

• Journal of Gastric Cancer
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• v.20 no.1
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• pp.81-94
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• 2020

Purpose: Duodenal stump leakage (DSL) is a potentially fatal complication that can occur after gastrectomy, but its underlying risk factors are unclear. This study aimed to investigate the risk factors and management of DSL after laparoscopic radical gastrectomy for gastric cancer (GC). Materials and Methods: Relevant data were collected from several prospective databases to retrospectively analyze the data of GC patients who underwent Billroth II (B-II) or Rouxen-Y (R-Y) reconstruction after laparoscopic gastrectomy from 2 institutions (Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, and HwaMei Hospital, University of Chinese Academy of Sciences). The DSL risk factors were analyzed using univariate and multivariate analysis regression. Results: A total of 810 patients were eligible for our analysis (426 with R-Y, 384 with B-II with Braun). Eleven patients had DSL (1.36%). Body mass index (BMI), elevated preoperative C-reactive protein (CRP) level, and unreinforced duodenal stump were the independent risk factors for DSL. DSL was diagnosed in 2-12 days, with a median of 8 days. Seven patients received conservative treatment, 3 patients received puncture treatment, and only 1 patient required reoperation. All patients recovered successfully after treatment. Conclusions: The risk factors of DSL were BMI ≥24 kg/㎡, elevated preoperative CRP level, and unreinforced duodenal stump. Nonsurgical treatments for DSL are preferred.