• Journal of KIISE:Information Networking
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• v.31 no.3
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• pp.298-304
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• 2004

In transmitting a compressed video bit-stream over Internet, a packet loss causes an error propagation in both spatial and temporal domain, which in turn leads to a severe degradation in image quality. In this paper, a new error concealment algorithm is proposed to repair damaged portions of the video frames in the receiver. Conventional BMA(Boundary Matching Algorithm) assumes that the pixels on the boundary of the missing block and its neighboring blocks are very similar, but has no consideration of edges t)r discontinuity across the boundary. In our approach, the edges are detected across the boundary of the lost or erroneous block. Once the edges are detected and the orientation of each edge is found, only the pixel difference along the expected edges across the boundary is measured instead of calculating differences between all adjacent pixels on the boundary. Therefore, the proposed approach needs very few computations and the experiment shows an improvement of the performance over the conventional BMA in terms of both subjective and objective quality of video sequences.

• Polymer(Korea)
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• v.30 no.6
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• pp.492-497
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• 2006

The epoxy composites are prepared with mixing temperature of epoxy/montmorillonite (MMT) melt master batch and the dielectric properties of the composites are also compared with intercalation of MMT. The exfoliation mainly occurrs iii the low content of MMT composites, while in the composites with high content of MMT the interspacing distance increases as the mixing temperature of epoxy/MMT master batch is increased. Class transition temperature of the composite which the MMT are effectively exfoliated is increased with the appropriate postcuring condition. Since the orientation polarization of dipoles in the epoxy molecules is restricted by the clay nanolayers exfoliated, the dielectric constant and dielectric loss of the composites are reduced. Furthermore, the dielectric properties could be improved by controling the mixing temperature and time of epoxy/MMT master batch as well as postcuring condition.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.600-608
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• 2013

Amide analogs of tridecapeptide ${\alpha}$-factor (WHWLQLKPGQPMYCONH$_2$) of Saccharomyces cerevisiae, in which Trp at position 1 and 3 were replaced with other residues, were synthesized to ascertain whether cooperative interactions between two Trp residues occurred upon binding with its receptor. Analogs containing Ala or Aib at position 3 of the peptide $[Ala_3]{\alpha}$-factor amide (2) and $[Aib_3]{\alpha}$-factor amide (5) exhibited greater decreases in bioactivity than analogs with same residue at position one $[Ala^1]{\alpha}$-factor amide (1) and $[Aib^1]{\alpha}$-factor amide (4), reflecting that $Trp^3$ may plays more important role than $Trp^1$ for agonist activity. Analogs containing Ala or Aib in both position one and three 3, 6 exhibited complete loss of bioactivity, emphasizing both the essential role and the combined role of two indole rings for triggering cell signaling. In contrast, double substituted analog with D-Trp in both positions 9 exhibited greater activity than single substituted analog with D-Trp 8 or deleted analog 7, reflecting the combined contribution of two tryptophane residues of ${\alpha}$-factor ligand to activation of Ste2p through interaction with residue $Tyr^{266}$ and importance of the proper parallel orientation of two indole rings for efficient triggering of signal G protein coupled activation. Among ten amide analogs, $[Ala^{1,3}]{\alpha}$-factor amide (3), $[Aib^{1,3}]{\alpha}$-factor amide (6), [D-$Trp^3]{\alpha}$-factor amide (8) and [des-$Trp^1,Phe^3]{\alpha}$-factor amide (10) were found to have antagonistic activity. Analogs 3 and 6 showed greater antagonistic activity than analogs 8 and 10.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.136-142
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• 2010

Ectopic eruption is defined as the eruption of the tooth in an abnormal position or orientation. In the molar region, ectopic eruption may cause distal root resorption and premature exfoliation of the neighbor teeth and uncontrolled space loss is followed. Prolonged partial impaction of the permanent molar may also cause undetected caries or abscess formation of the neighbor teeth. While 66% of ectopically erupting permanent molars are corrected spontaneously without treatment, the treatment is necessary for the irreversible ectopic eruption cases. The optimal treatment approach depends on a number of factors including the clinical eruption status of the molar, amount of enamel ledge and the mobility of the neighbor tooth, and the presence of pain or infection. This case report presents the results of treatment of the ectopically erupting maxillary first permanent molars and mandibular second molars using elastic separators or modified Halterman appliance with or without surgical approach.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.1-11
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• 2004

To evaluate the applicability of dielectric constant measurement method on the geoenvironmental investigation of subsurface contaminated by landfill leachate, the analysis on dielectric characteristics of sand containing contaminated pore water by landfill leachate was performed. The separate real and imaginary parts of dielectric constant were investigated in the frequency range of 75kHz to 12MHz. The real part of dielectric constant increased at the lower frequency wherea the real part of dielectric constant decreased at the higher frequency as the concentration of leachate increased. These results can be explained by the frequency dependence of space charge polarization and orientation polarization. The imaginary part of dielectric constant on the contaminated sand with leachate increased with their concentration for whole frequency range. These results are caused by the increase of energy loss due to the enhancement of conduction in soil with leachate concentration. The results in this study indicate that the dielectric constant measurement method has potential in evaluating the contaminated soil and pore water by landfill leachate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.999-1005
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• 2011

The effects of strain-induced crystallization (SIC) on the mechanical properties of elastomeric composites as functions of extension ratio (${\lambda}$), multiwalled carbon nanotube (CNT) content, and carbon black (CB) content are investigated. The differential scanning calorimetry (DSC) analysis shows that the degree of crystallinity increases with the increase in the CB and CNT content. As ${\lambda}$ increases, the glass transition temperature (Tg) of the composites increases, and the latent heat of crystallization (LHc) of the composites is maximum at ${\lambda}$=1.5. It is found that the mechanical properties have a linear relation with LHc, depending on the CNT content. According to the TGA (thermogravimetric analysis), the weight loss of the composite matrix is 94.3% and the weight of the composites decreases with the filler content. The ratio of tensile modulus ($E_{comp}/E_{matrix}$) is higher than that of tensile strength (${\sigma}_{comp}/{\sigma}_{matrix}$) because of the CNT orientation inside the elastomeric composites.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.349-356
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• 2022

Currently, the agricultural population in Korea indicates a decreasing and aging orientation. As the population of farm labor continues to decline, so farmers are feeling the pressure to be stable crop production. To solve the problem caused by the decreasing of farm labor, it is necessary to change over to "Digital agriculture". Digital agriculture is tools that digitally collect, store, analyze, and share electronic data and/or information in agriculture, and aims to integrate the several digital technologies into crop and livestock management and other processes in agriculture fields. In addition, digital agriculture can offer the opportunity to increase crop production, save costs for farmer. Therefore, in this study, for data-based Digital Agriculture, a greenhouse environment monitoring system for crop growth monitoring based on Node-RED, which even beginners can use easily, was developed, and the implemented system was verified in a hydroponic greenhouse. Several sensors, such as temperature, humidity, atmospheric pressure, CO₂, solar radiation, were used to obtain the environmental data of the greenhouse. And the environmental data were processed and visualized using Node-RED and MariaDB installed in rule.box digital. The environment monitoring system proposed in this study was installed in a hydroponic greenhouse and obtained the environmental data for almost two weeks. As a result, it was confirmed that all environmental data were obtained without data loss from sensors. In addition, the dashboard provides the names of installed sensors, real time environmental data, and changes in the last three days for each environmental data. Therefore, it is considered that farmers will be able to easily monitor the greenhouse environment using the developed system in this study.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.414-420
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• 2001

A 30-kV plasma immersion ion implantation setup (P $I^3$) has been equipped with a self-developed 6'-magnetron to perform hard coatings with enhanced adhesion by P $I^3$D(P $I^3$ assisted deposition) process. Using ICP source with immersed Ti antenna and reactive magnetron sputtering of Ti target in $N_2$/Ar ambient gas mixture, the TiN films were prepared on Si substrates at different pulse bias and ion-to-atom arrival ratio ( $J_{i}$ $J_{Me}$ ). Prior to TiN film formation the nitrogen implantation was performed followed by deposition of Ti buffer layer under A $r^{+}$ irradiation. Films grown at $J_{i}$ $J_{Me}$ =0.003 and $V_{pulse}$=-20kV showed columnar grain morphology and (200) preferred orientation while those prepared at $J_{i}$ $J_{Me}$ =0.08 and $V_{pulse}$=-5 kV had dense and eqiaxed structure with (111) and (220) main peaks. X-ray diffraction patterns revealed some amount of $Ti_{x}$ $N_{y}$ in the films. The maximum microhardness of $H_{v}$ =35 GN/ $M^2$ was at the pulse bias of -5 kV. The P $I^3$D technique was applied to enhance wear properties of commercial tools of HSS (SKH51) and WC-Co alloy (P30). The specimens were 25-kV PII nitrogen implanted to the dose 4.10$^{17}$ c $m^{-2}$ and then coated with 4-$\mu\textrm{m}$ TiN film on $Ti_{x}$ $N_{y}$ buffer layer. Wear resistance was compared by measuring weight loss under sliding test (6-mm $Al_2$ $O_3$ counter ball, 500-gf applied load). After 30000 cycles at 500 rpm the untreated P30 specimen lost 3.10$^{-4}$ g, and HSS specimens lost 9.10$^{-4}$ g after 40000 cycles while quite zero losses were demonstrated by TiN coated specimens.s.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• Polymer(Korea)
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• v.33 no.3
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• pp.224-229
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• 2009

The dielectric properties of semi-IPN poly(phenylene oxide)(PPO) blend/$BaTiO_3$(BT) composites are investigated. The composites are fabricated via melt-mixing of crosslinker and peroxide in precursor PPO composite obtained by precipitating the suspension consisted of PPO, BT and toluene into methylethyl ketone, poor solvent of PPO. The permittivity of the precursor PPO composites shows higher value than that of integral-blended PPO composites by extruder and coincides with the theoretical value calculated by logarithmic rule of mixture. The blend of PPO and cross-linked triallyl isocyanurate is most effective for lowering the permittivity and loss tangent owing to the suppression of the orientation polarization of matrix. In contrast, 4,4'-(1,3-phenylene diisopropylidene) bisaniline, which has amine unit in its structure, increases the permittivity as well as loss tangent of the composite, but it has the ability to densify the matrix resin and the interfacial adhesion between the matrix and filler to improves flexural strength and modulus.