• The Journal of the Acoustical Society of Korea
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• v.11 no.4
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• pp.36-44
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• 1992

To reduce the redundancy within samples that resulted from uniform sampling method, nonuniform sampling or nonredundant-sample coding methods can be considered. But it is well-known that when conventional nonuniform sampling methods are applied directly to speech signal, the amount of data required is comparable to or more than that required by uniform sampling method like PCM. To overcome this problem, we consider properties of speech signal in the sense of perception, and suggest a nonuniform sampling method at the maxima and minima of speech wave. To analyze the performance of the suggested method, compression ratio is considered. We show that compression ratio can be improved by silence detection, which can't be implemented by conventional methods based on uniform sampling. As experimental results, compression ratios of 1.54 without silence detection and 2.88 with silence detection for 8kHz 8-bit PCM signals are obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.119-124
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• 2010

The MAC layer in ad-hoc network which makes network of nodes without infrastructure for a time has became an issue to reduce delay, allocate fairly bandwidth, control TX/RX power and improve throughput. Specially, the problem to reduce power consumption in ad-hoc network is very important part as ad-hoc devices use the limited battery. For solution of the problem, many power control algorithms, such as distribute power control, PCM (Power Control MAC) and F-PCF (Fragmentation based PCM), are proposed to limit power consumption until now. Although the algorithms are designed to minimize power consumption, the latency communication zone is generated by power control of RX/TX nodes. However the algorithms don't suitably reuse the space. In this paper proposes the algorithm to improve data throughput through Spatial Reuse based on a power control method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.8
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• pp.432-437
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• 2013

The increase of greenhouse gas emission and decrease of fossil fuel are being caused by the indiscreet consumption of energy by people. Recently, green policy has been globally implemented to reduce energy consumption. This paper studied the research to reduce the energy consumption in buildings, by using the heat storage properties of PCM. PCM has to prevent leakage from the liquid state. Therefore, we prepared form stable PCM, by using the vacuum impregnation method. Three kinds of organic PCMs were impregnated into the structure of porous material. The characteristics of the composites were determined by using SEM, DSC, FTIR and TGA. SEM morphology showed the micro structure of silica fume/PCM. Also, thermal properties were examined by DSC and TGA analyses; and the chemical bonding of the composite was determined by FTIR analysis.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.258-267
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• 1993

A mathematical model has been developed to describe heat transfer phenomena in a PCM (phase change material) module for development of an energy recovery system. The PCM module, melting point of which is around 1673 K, consists of silicon(96.8%), aluminium(2.7%) and marginal amounts of impurities such as Ca, Fe and Ti. The module is covered by a capsule that consists of SiC(58%) and graphite(42%). Physical properties that are required for model predictions were cited from the references. The apparent capacity method and the postiterative method wert used in the mathematical model to describe the phase changing mechanism. Temperature and velocity of fluid are the major variables in the model calculation. For the gas temperature of 1773 K that simulates real operating conditions, the prediction shows that PCM is rapidly melted to axial direction. However, for the gas temperature of 3000 K that is higher than the real conditions, PCM is melted rapidly to the radial direction. The gas velocity has no influence on the melting phenomena of the PCM except when the gas velocity is relatively low. At the low gas velocity asymmetry of the temperature profiles in PCM is obtained.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1319-1324
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• 2010

The objectives of this study were to compare the effectiveness of different indicators of mammary inflammation in buffalo and to evaluate the association of the indicators with buffalo milk yield, composition, and rennet coagulation properties. This study was carried out at four buffalo farms in central Italy using a total of 50 lactating buffalo. Milk from each buffalo was tested at the beginning, middle, and end of lactation. To evaluate the relationship between mastitis markers and milk components, three classes were defined for each of the following markers: total somatic cell count (TSCC), differential somatic cell count (DSCC), and bacteriological results The regression coefficient for the reference method and the alternative method of determining TSCC was 0.81, indicating that the method routinely used to analyze buffalo milk consistently underestimated actual TSCC. The milk samples positive for udder-specific bacteria also had higher TSCC values than the samples that were negative for bacteria ($872{\times}10^3$/ml vs. $191{\times}10^3$/ml). In samples that were positive for udder-specific bacteria, polymorphonuclear leukocytes (PMN) made up greater than 50% of the cells. Moreover, only 1% of the samples in the lowest TSCC class were positive for bacteria. The correlation between TSCC and PMN was stronger (0.70), and PMN values in buffalo milk increased significantly when the TSCC class changed from low (38%) to medium and high (56% and 64%). Milk yield was negatively related to TSCC. Significant changes in lactose (4.87%, 4.80% and 4.64%) and chloride content (0.650 mg/ml, 0.862 mg/ml and 0.882 mg/ml) were also observed with increasing TSCC values. Higher TSCC was associated with impaired rennet coagulation properties: the clotting time increased, while the curd firming time ($p{\leq}0.05$) and firmness decreased. We concluded that in buffalo as in dairy cows, TSCC is a valid indicator of udder inflammation; we also confirmed that a value of $ 200{\times}10^3 cells/ml should be used as the threshold value for early identification of an animal affected by subclinical mastitis. In addition to its association with significantly decreased milk yield, a TSCC value above this threshold value was associated with changes in milk composition and coagulating properties.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.185-191
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• 2007

Remote sensing images are multispectral image data collected from several band divided by wavelength ranges. The classification of remote sensing images is the method of classifying what has similar spectral characteristics together among each pixel composing an image as the important algorithm in this field. This paper presents a pattern classification method of remote sensing images by applying a possibilistic fuzzy c-means (PFCM) algorithm. The PFCM algorithm is a hybridization of a FCM algorithm, which adopts membership degree depending on the distance between data and the center of a certain cluster, combined with a PCM algorithm, which considers class typicality of the pattern sets. In this proposed method, we select the training data for each class and perform supervised classification using the PFCM algorithm with spectral signatures of the training data. The application of the PFCM algorithm is tested and verified by using Landsat TM and IKONOS remote sensing satellite images. As a result, the overall accuracy showed a better results than the FCM, PCM algorithm or conventional maximum likelihood classification(MLC) algorithm.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.282-293
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• 2017

A new modified carbon paste electrode (CPE) was constructed based on nickel oxide nanoparticles (NiONPs) and graphene nanosheets (Gr) for simultaneous determination of paracetamol (PCM) and mefenamic acid (MFA) in aqueous media and pharmaceutical dosage forms. NiONPs were synthesized via a simple and inexpensive technique and characterized using X-ray diffraction method. Scanning electron microscopy was used for the characterization of the morphology of modified carbon paste electrode (NiONPs/Gr/CPE). Voltammetric studies suggest that the NiONPs and Gr provide a synergistic augmentation that can increase current responses by improvement of electron transfers of these compounds on the NiONPs/Gr/CPE surface. Using cyclic voltammetry, the NiONPs/Gr/CPE showed good sensitivity and selectivity for the determination of PCM and MFA in individually or mixture standard samples in the linear range of $0.1-30{\mu}g\;mL^{-1}$. The resulted limit of detection and limit of quantification were 20 and $60ng\;mL^{-1}$ for PCM, 24 and $72ng\;mL^{-1}$ for MFA, respectively. The analytical performance of the NiONPs/Gr/CPE was evaluated for the determination of PCM and MFA in pharmaceutical dosage forms with satisfactory results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.109-118
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• 2004

No.2 PCM (Pickling and tandem cold rolling mill) at Pohang works was revamped in 2003. The purpose of this project is to produce carbon and stainless steel using conventional carbon production process, rolling and annealing. This paper introduces the applied facilities and technologies of PCM which are used in production of carbon and stainless steel. To realize the main purpose of this project, POSCO have developed laser weld technology in normal carbon and special steel (stainless, high carbon and high silicon). And this report describes the method which is developed to get down the surface defect of stainless 400 series. After revamping, No.2 PCM can have competitive power in this field and can supply the special steel using carbon rolling process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.2 s.257
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• pp.245-252
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• 2007

Since the new millennium, truss PCMs(Periodic Cellular Metals) have drawn attention because of their superior specific stiffness, strength and multi-functionality. Prior studies have focused on the structural design and optimization. Kagome truss PCM has been proved to have the higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. In this study, we introduce a new idea to fabricate multi-layered Kagome truss PCM from continuous wires which can gain high strength as in piano wires and can be controlled to be defect free owing to drawing process. The relative density, the stiffness and the strength under bending and compressive load are estimated through elementary mechanics and compared with the results from experiments and FEA. The failure mechanisms are analyzed, and also mechanical performance and production are discussed.

• ETRI Journal
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• v.9 no.2
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• pp.96-105
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• 1987

The purpose of this paper is to report the implementation of new frame synchroniazation circuit for D3/PCM.When the D3/PCM signal(1.544Mb/s) is received, the performance of the new frame synchronizer is evaluated by the statistical method according to the parameters BER,es, em. For BER=$10^-2$, es=0 and em=2, the implemented hardware will render the initial search time, the maintenance time and there frame time equals to 2.87ms, 9.9hrs and2.69ms, respectively. Also the proposed frame synchronizer can be easily modified to the practical transmission channels environment and the new 1.544Mb/s signal format.