• ETRI Journal
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• v.31 no.1
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• pp.21-30
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• 2009

In low bit-rate video transmission, the payload of a single packet can often contain a whole coded frame due to the high compression ratio in both spatial and temporal domains of most modern video coders. Thus, the loss of a single packet not only causes the loss of a whole frame, but also produces error propagation into subsequent frames. In this paper, we propose a novel whole frame error concealment algorithm which reconstructs the first of the subsequent frames instead of the current lost frame to suppress the effects of error propagation. In the proposed algorithm, we impose a constraint which uses side match distortion (SMD) and overlapped region difference (ORD) to estimate motion vectors between the target reconstructed frame and its reference frame. SMD measures the spatial smoothness connection between a block and its neighboring blocks. ORD is defined as the difference between the correlated pixels which are predicted from one reference pixel. Experimental results show that the proposed algorithm effectively suppresses error propagation and significantly outperforms other conventional techniques in terms of both peak signal-to-noise ratio performance and subjective visual quality.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.818-826
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• 2004

The spray-induced mixing characteristics and thermal decomposition of aqueous urea solution into ammonia have been studied to design optimum sizes and geometries of the mixing chamber in SCR(Selective Catalytic Reduction) system. The cold flow tests about the urea-injection nozzle were performed to clarify the parameters of spray mixing characteristics such as mean diameter and velocity of drops and spray width determined from the interactions between incoming air and injected drops. Discrete particle model in Fluent code was adopted to simulate spray-induced mixing process and the experimental results on the spray characteristics were used as input data of numerical calculations. The simulation results on the spray-induced mixing were verified by comparing the spray width extracted from the digital images with the simulated Particle tracks of injected drops. The single kinetic model was adopted to predict thermal decomposition of urea solution into ammonia and solved simultaneously along with the verified spray model. The hot air generator was designed to match the flow rate and temperature of the exhaust gas of the real engines The measured ammonia productions in the hot air generator were compared with the numerical predictions and the comparison results showed good agreements. Finally, we concluded that the design capabilities for sizing optimum mixing chamber were established.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.447-449
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• 2012

There are many essential elements in making the realistic 3D games, of which one of the most important is mapping. Mapping can add the details to 3D objects easily, which are impossible or difficult by modeling alone, and can reduce file data capacities to run the game engine. The theory of the mapping is to throw 2D image on 3D object correctly, but they do not match each other at the rate of 1:1 100 percent completely due to the difference of the fundamental property of them. To solve this problem, various kinds of mapping methods are developed and used. This paper will compare and analyze the characteristics, and merits and demerits of these various kinds of mapping methods and will inquire which method is the most efficient one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1465-1474
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• 1992

This paper describes a new overlapped object recognition method using extended local features. At first, we extract the extended local features consisting of corners, arcs, parallel-lines, and corner-arcs from the images consisting of model objects. Based on the extended local features we construct a knowledge-base. In order to match objects, we also extract the extended local features from the input image, and then check the compatibility between the extracted features and the features in the knowledge-base. From the set of compatible features, we compute geometric transforms. If any geometric transforms are clustered, we generate the hypothesis of the objects as the centers of the clusters, and then verify the hypothesis by a reverse geometric transform. An experiment shows that the proposed method increases the recognition rate and the accuracy as compared with existing methods.

• Journal of Chest Surgery
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• v.36 no.2
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• pp.101-104
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• 2003

Although lung transplantation has been accepted as the most effective treatment for end-stage pulmonary emphysema, it is not only very hard to find a donor but also to obtain a relatively healthy lung. Furthermore, it is more difficult to match the size of the allograft, considering the height, the weight, and the size of the thoracic cage. The single lung transplatations for the end-stage emphysema have been more commonly performed than bilateral lung transplantation due to the shortage of the donors and the long-term survival rate of the single lung transplantations has shown no reasonable difference compared with that of the bilateral lung transplantationh. Recently, the functional criteria based on a comparison of predicted TLCs(Total Lung Capacities) of the donor and recipient according to height, sex and age, have been accepted at a more suitable.

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.155-162
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• 2017

Purpose: The objective of this study was to evaluate the biogas productivity of agricultural by-products (ABPs) based on their proximate composition. Specifically, the effects of proximate composition were investigated, and a new mixing method was developed using various ABPs that are difficult to digest for biogas production. Methods: Experiments were conducted to compare the biogas productivity between a single ABP and a mixture of ABPs that had the same proximate composition as the single ABP. To match the proximate compositions of radish waste and corn distiller's dried grains with solubles (DDGS), mixed ABPs were made from various ABPs. Biogas potential tests (BMP tests) were performed at an organic loading rate (OLR) of 2.5 g VS/L and a feed to microorganism ratio (F/M) of 0.5 under the mesophilic condition. Results: The individual ABPs (radish and corn DDGS) and the mixed ABPs (cabbage waste with skim milk waste, bean-curd waste with skim milk waste, and some others) produced similar amounts of biogas. Conclusions: The new mixing method based on proximate composition can be applied to other ABPs and organic wastes from factories and municipal waste treatment plants to develop renewable energy and effective waste treatment methods.

• Korean Journal of Head & Neck Oncology
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• v.4 no.1
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• pp.21-28
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• 1988

Skin replacement in large cheek defects after excision of benign or malignant tumor on the face is a challenging task. The physical characteristics of cheek skin are matched best by adjacent skin. Various methods of reconstructing of the facial surface such as forehead flap, distant flap, or a full thickness or split thickness skin graft have replaced adjacent tissue for coverage in many cases. We have reviewed ten cases of aesthetic reconstruction of the face after resection of the facial skin tumor within the last 5 years. The first group of 3 patients were reconstructed with split thickness skin graft from the scalp or lower abdomen. The second group of patients were reconstructed with cheek flap. The third group of 3 patients were reconstructed with cervicofacial flap. The last 2 patients were reconstructed with nasolabial flap & island falp respectively. The advantages from our experience with various method of coverage are its hidden donor area & good color match with the facial skin & increased success rate.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.57.1-57.1
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• 2011

Using high-resolution numerical simulations, we investigate the formation of gaseous substructures and mass inflow rates in barred spiral galaxies in the presence of both bar and spiral potentials. The gaseous medium is assumed to be infinitesimally-thin, isothermal, unmagnetized, and non-self-gravitating. To consider various galactic situations, we vary the pattern speed and strength of spiral arms as well as the black hole mass. We find that spiral arms with pattern speed smaller than that of the bar remove angular momentum from the gas outside corotation which transports to the bar region, making the dust lanes strong and live long. When the arm pattern speed is identical to that of the bar, on the other hand, the gas outside corotation gains angular momentum and thus moves outward, without affecting the bar region. Overall gaseous morphologies in simulations match well with observed IR images of barred spiral galaxies such as NGC 1097, when the arms and bar are in phase at the corotation radius. The presence of spiral arms increases the mass inflow rate as well, making it larger than $0.01M_{\odot}/yr$ when MBH is $4{\times}10^7M_{\odot}$, possibly explaining AGN activities in Seyfert galaxies.

• ETRI Journal
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• v.32 no.1
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• pp.11-21
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• 2010

A novel ultra-wideband (UWB) transceiver structure is presented to be used in wireless body area networks (WBANs). In the proposed structure, a data channel and a control channel are combined into a single transmission signal. In the signal, a modulation method mixing pulse position modulation and pulse amplitude modulation is proposed. A mathematical framework calculating the power spectrum density of the proposed pulse-based signal evaluates its coexistence with conventional radio systems. The transceiver structure is discussed, and the receiving performance is investigated in the additive white Gaussian noise channel. It is demonstrated that the proposed scheme is easier to match to the UWB emission mask than conventional UWB systems. The proposed scheme achieves the data rate requirement of WBAN; the logical control channel achieves better receiving performance than the logical data channel, which is useful for controlling and maintaining networks. The proposed scheme is also easy to implement.