• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.924-933
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• 2008

This paper proposes a novel LDPC code decoder architecture to improve throughput for DVB-S2, a second generation standard of ETSI for satellite broad-band applications. The proposed architecture clusters 360 bitnodes and checknodes into groups utilizing the property of IRA-LDPC code. Functional modules which perform calculations for bitnode groups and checknode groups have local memories and store the messages from the other type of functional modules connected by edges at their local memories. The proposed architecture can avoid memory conflicts by accessing stored messages sequentially, hence, increases throughput in the proposed DVB-S2 LDPC code decoder architecture. The proposed architecture was synthesized using the TSMC 90nm technology. Synthesis results show that throughput of the proposed architecture is improved by 104% and 478%, respectively, when compared with those of the architectures proposed by F. Kienle and J. Dielissen.

• Bulletin of the Korean Mathematical Society
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• v.48 no.4
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• pp.673-688
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• 2011

Let $n{\geq}2$ be an even integer. We investigate that if an odd mapping f : X ${\rightarrow}$ Y satisfies the following equation $2_{n-2}C_{\frac{n}{2}-1}rf\(\sum\limits^n_{j=1}{\frac{x_j}{r}}\)\;+\;{\sum\limits_{i_k{\in}\{0,1\} \atop {{\sum}^n_{k=1}\;i_k={\frac{n}{2}}}}\;rf\(\sum\limits^n_{i=1}(-1)^{i_k}{\frac{x_i}{r}}\)=2_{n-2}C_{{\frac{n}{2}}-1}\sum\limits^n_{i=1}f(x_i),$ then f : X ${\rightarrow}$ Y is additive, where $r{\in}R$. We also prove the stability in normed group by using shadowing property and the Hyers-Ulam stability of the functional equation in Banach spaces and in Banach modules over unital C-algebras. As an application, we show that every almost linear bijection h : A ${\rightarrow}$ B of unital $C^*$-algebras A and B is a $C^*$-algebra isomorphism when $h(\frac{2^s}{r^s}uy)=h(\frac{2^s}{r^s}u)h(y)$ for all unitaries u ${\in}$ A, all y ${\in}$ A, and s = 0, 1, 2,....

• Journal of the Korea Convergence Society
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• v.13 no.3
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• pp.33-41
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• 2022

In this article, we proposed to predict natural gas (NG) leakage levels through feature selection based on a factor analysis (FA) of the integrating the Korean Meteorological Agency data and natural gas leakage data for considering complex factors. The paper has been divided into three modules. First, we filled missing data based on the linear interpolation method on the integrated data set, and selected essential features using FA with OrdinalEncoder (OE)-based normalization. The dataset is labeled by K-means clustering. The final module uses four algorithms, K-nearest neighbors (KNN), decision tree (DT), random forest (RF), Naive Bayes (NB), to predict gas leakage levels. The proposed method is evaluated by the accuracy, area under the ROC curve (AUC), and mean standard error (MSE). The test results indicate that the OrdinalEncoder-Factor analysis (OE-F)-based classification method has improved successfully. Moreover, OE-F-based KNN (OE-F-KNN) showed the best performance by giving 95.20% accuracy, an AUC of 96.13%, and an MSE of 0.031.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1333-1340
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• 2002

The objective of this study is to develop a thermoelectric generation system which converts unused energy from close-at-hand sources such as garbage incineration heat and industrial exhaust etc. into electricity. This paper presents applicability of a commercially available thermoelectric generator f3r waster heat recovery. The test facility consists of water heater, pump, thermoelectric module and aluminium tubes and hot and cold water is used as heat source and sink fluids. It is shown that the three components of thermoelectric research exist in manufacturing a thermoelectric generator. The first component is fabrication of thermoelectric materials, the second is manufacturing of thermoelectric generator with 32 thermoelectric modules. The last one is characteristic measuring of thermoelectric generator with 32 thermoelectric modules of two types, cooling and power purpose. It was found that the rate of cold and hot water is 25 and 37 liter per minute and the maximum power of thermoelectric generator is 28Watts and its efficiency is 1.04%.

• Membrane and Water Treatment
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• v.4 no.1
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• pp.53-67
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• 2013

In this study, ageing characteristics of an industrial hollow-fiber membrane module were investigated after 50 months of drinking water production. For this purpose, the industrial module was opened to make 18 smaller modules with hollow-fibers taken from different parts of the industrial module. These modules were probed by the use of a magnetic nanoparticle (NP) challenge test based on magnetic susceptibility (K) measurement of permeate. No magnetic susceptibility was detected in permeate when the challenge test was performed on an intact membrane module, indicating the complete retention of nanoparticles by the membrane. The compromised membrane module can be successfully detected by means of magnetic susceptibility measurement in permeate. So, this study clearly demonstrates that ageing of ultrafiltration membranes can be monitored by measuring the magnetic susceptibility of permeate from an ultrafiltration membrane module. These results showed that the hollow fibers in the center zones of the bundle would age faster than those in the outer zones around the bundle. This result is in agreement with numerical simulation (Daurelle et al. 2011).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.215-222
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• 2009

Many concepts of external magnetic field applications in crystal growth processes have been developed to control melt convection, impurity content and growing interface shape. Especially, travelling magnetic fields (TMF) are of certain advantages. However, strong shielding effects appear when the TMF coils are placed outside the growth vessel. To achieve a solution of industrial relevance within the framework of the $KRISTMAG^{(R)}$ project inner heater-magnet modules(HMM) for simultaneous generation of temperature and magnetic field have been developed. At the same time, as the temperature is controlled as usual, e.g. by DC, the characteristics of the magnetic field can be adjusted via frequency, phase shift of the alternating current (AC) and by changing the amplitude via the AC/DC ratio. Global modelling and dummy measurements were used to optimize and validate the HMM configuration and process parameters. GaAs and Ge single crystals with improved parameters were grown in HMM-equipped industrial liquid encapsulated Czochralski (LEC) puller and commercial vertical gradient freeze (VGF) furnace, respectively. The vapour pressure controlled Czochralski (VCz) variant without boric oxide encapsulation was used to study the movement of floating particles by the TMF-driven vortices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.328-328
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• 2008

As a low K material for high frequency high integration modules, glass/ceramic composites were investigated. Glass composition were selected from $SiO_2-B_2O_3-Al_2O_3-R_2O$-RO system which having very low dielectric constant and cordierite was used as a ceramic filler. These composites were sintered at temperature range from $850^{\circ}$ to $950^{\circ}$ and XRD, SEM microstructure analysis of sintered bodies were performed for understanding sintering behavior. Any crystallization was not occurred and dense sintered bodies were attained. Dielectric and mechanical properties of these sintered glass/cordierite composites were analysed by network analyzer and UTM. Glass/ceramic composite with 50 wt% cordierite showing a dielectric constant (${\varepsilon}_r$) of 5.4, Q${\times}f_0$ (Q) of 1600 at 1 GHz and maximum bending strength of 163 MPa was attained.

• Membrane Journal
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• v.12 no.4
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• pp.226-239
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• 2002

A process simulation model of pervaporation process has been developed as a design tool to analyse and optimize the dehyhration of organic solvents through a commercial scale of pervaporative plate-and-frame modules that contain a stack of membrane sheets. In the simulation model, the mass balance, the heat balance and the concentration balance are integrated in a finite elements-in-succession method to simulate the overall process. In the integration method, a feed channel between membrane sheets in the modules was taken as differential unit element volume to simplify calculation procedure and shorten computing time. Some of permeation parameters used in the simulation model, were quantified directly from the dehydration experiment of ethanol through $AzeoSep^{TM}$-2002 membrane which is a commercial pervaporation membrane. The simulation model was verified by comparing the simulated values with experimental data. Using the model, continuous and batch pervaporation processes were simulated, respectively, to acquire basic data for analysing and optimizing in the dehydration of ethanol through the membrane. Based on the simulation results, a comparison between the continuous and the batch pervaporation processes would be discussed.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.81-87
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• 1997

This paper presents the optimum initial design containing the first and third order properties of the four-group video camera zoom system using lens modules, and its real lens design. The optimum initial design with focal length range of 6.1693 to 58.4065 mm is derived by assigning appropriate first order quantities and third order aberrations to each module along with the specific constraints required for optimization. By scaling the focal length of each lens group, an initial real lens selected for each group has been designed to match its focal length into that of the each lens module, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system consisting of original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in video zoom camera employing the rear focus method.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.715-719
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• 2003

The Aerosol Deposition (AD) process will be proposed as a new fabrication technology for the integrated RF modules. $\alpha$-A1$_2$O$_3$ thick films were successfully grown on glass and Al substrates at room temperature by the AD process. Relative dielectric permittivity and loss tangent of the $Al_2$O$_3$ thick films on Al showed 9.5 and 0.005, respectively. To form microstrip lines on aerosol-deposited A1903 thick films, copper electroplating and lithography processes were employed, and the square-type cross section with sharp edges could be obtained. Low-pass LC filters with 10 GHz cutoff frequency were simulated by an electromagnetic analysis, exhibiting the validity of the AD process as a fabrication technology f3r integrated RF modules.