• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.137-146
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• 2002

Purpose : This paper introduces an improved classification approach which adopts a deterministic relaxation method and an agglomerative clustering technique for the classification of MRI using neural network. The proposed approach can solve the problems of convergency to local optima and computational burden caused by a large number of input patterns when a neural network is used for image classification. Materials and methods : Application of Hopfield neural network has been solving various optimization problems. However, major problem of mapping an image classification problem into a neural network is that network is opt to converge to local optima and its convergency toward the global solution with a standard stochastic relaxation spends much time. Therefore, to avoid local solutions and to achieve fast convergency toward a global optimization, we adopt MFA to a Hopfield network during the classification. MFA replaces the stochastic nature of simulated annealing method with a set of deterministic update rules that act on the average value of the variable. By minimizing averages, it is possible to converge to an equilibrium state considerably faster than standard simulated annealing method. Moreover, the proposed agglomerative clustering algorithm which determines the underlying clusters of the image provides initial input values of Hopfield neural network. Results : The proposed approach which uses agglomerative clustering and deterministic relaxation approach resolves the problem of local optimization and achieves fast convergency toward a global optimization when a neural network is used for MRI classification. Conclusion : In this paper, we introduce a new paradigm to classify MRI using clustering analysis and deterministic relaxation for neural network to improve the classification results.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.61-72
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• 2008

Leaf area index (LAI) is a key biophysical variable influencing land surface processes such as photosynthesis, transpiration and energy balance, and is a required input to estimate evapotranspiration in various ecological and hydrological models. The development of more correct and useful LAIs estimation techniques is required by these importance, but LAIs had been assumed in most LAI research through simple relations with the normalized difference vegetation index (NDVI) because the field measurement is difficult on wide area. This paper is to evaluate the MODIS LAI Product's practical use by comparing with LAIs that is derived from NOAA AVHRR NDVIs and the 2 years (2003-2004) measured LAIs of Korea Forest Research Institute in Gyeongancheon watershed (561.12 $Km^2$). As a result, the MODIS LAIs of deciduous forests showed higher values about 14 % and 15~30 % than the measured LAIs and NOAA LAIs. In the year of 2003, the MODIS LAIs in coniferous forests were 5 % higher than the measured LAIs, and showed about 7 % differences comparing with the NOAA LAIs except April. These differences come from the insufficient field data measured in partial points of the target area, and the extracted reference data from MODIS LAIs include the limits of spatial resolution and the error of incorrect land cover classification. Thus, using the MODIS data by the proper correction with the measured data can be useful as an input data for ecological and hydrological models which offers the vegetation information and simulates the water balance of a given watershed.

• Journal of Astronomy and Space Sciences
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• v.21 no.2
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• pp.141-152
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• 2004

Optics fabrication process for precision space optical parts includes bound abrasive grinding, loose abrasive lapping and polishing. The traditional bound abrasive grinding with bronze bond cupped diamond wheel leaves the machine marks of about $20{mu}m$ rms in height and the subsurface damage of about 1 ${mu}m$ rms in height to be removed by subsequent loose abrasive lapping. We explored an efficient quantitative control of precision CNC grinding. The machining parameters such as grain size, work-piece rotation speed and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis. The effectiveness of such grinding prediction models was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment achieved the predictability down to ${pm}20$ nm in height and the surface roughness down to 36 nm in height. This study contributed to improvement of the process efficiency reaching directly the polishing and figuring process without the need for the loose abrasive lapping stage.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.192-200
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• 1998

This study was carried out to evaluate the effect of feeding higher protein feeds with lesser amount, but feeding the constant total protein input for all treatments, on water quality and nitrite toxicity in channel catfish ponds. There was no significant difference in survival rate among treatments $(P>0.05)$. Specific growth rate (SGR) for Treatment 1$(28\%\;protein\;and\;100\%\;of\;satiation)$ was significantly higher $(P>0.05)$ than for Treatment 3$(36\%\;protein\;and\;87.5\%\;of\;satiation)$, but not significantly higher than for Treatment 2 $(32\%\;protein\;and\;77.8\%\;of\;satiation)$ at constant digestible energy (DE), 3.08kcal/g (treatments 1, 2 and 3). At constant DE/P (treatments 4, 2 and 5), no significant difference in SGR was observed among treatments. Feed conversion ratio (FCR) slightly improved or improved as dietary protein level increased from $28\%$ to $32\%$ and feed allowance decreased by $12.5\%$, but did not improve as dietary protein level increased from $32\%$ to $36\%$ and feed allowance decreased by $22.2\%$, at constant DE and constant DE/P. There was no significant difference in water quality variables, such as total ammonia nitrogen (TAN), nitrite, chlorophyll a, soluble phosphorous concentrations among treatments, but significant difference in water quality variables over time as amount of feed fed increased $(P<0.0001)$. There was a trend toward increase in TAN and nitrite over time. A strong linear regression was observed between mean total ammonia nitrogen and nitrite for all treatments Y (Nitrite) =$0.04\times (TAN)+0.01$, $R_2=0.89$. Methemoglobin percent in the blood of catifish was not significantly different among treatments. And its mean value was $7.5\%$, which was relatively low, so that it was not serious problem in catfish production pond under these experiment conditions. There was the stronger linear regression between the percentage of Methemoglobin and the molar ratio of nitrite to chloride rather than nitrite alone: $Y\;(Methemoglobin\;\%)\;=\;58.45\;\times\;(NO^{2-}/Cl^-)\;+\;0.41,\;R^2=0.60$. These results indicate that deterioration of water quality has no strong impact on poor weight gain for $36\%$ dietary protein in this study.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.132-139
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• 2007

The Moderate Resolution Imaging Spectroradiometer (MODIS) regularly provides the eight-day gross primary productivity (GPP) at 1 km resolution. In this study, we evaluated the uncertainties of MODIS GPP caused by errors associated with the Data Assimilation Office (DAO) meteorology and a biophysical variable (fraction of absorbed photosynthetically active radiation, FPAR). In order to recalculate the improved GPP estimate, we employed ground weather station data and reconstructed cloud-free FPAR. The official MODIS GPP was evaluated as +17% higher than the improved GPP. The error associated with DAO meteorology was identified as the primary and the error from the cloud-contaminated FPAR as the secondary constituent in the integrative uncertainty. Among various biome types, the highest relative error of the official MODIS GPP to the improved GPP was found in the mixed forest biome with RE of 20% and the smallest errors were shown in crop land cover at 11%. Our results indicated that the uncertainty embedded in the official MODIS GPP product was considerable, indicating that the MODIS GPP needs to be reconstructed with the improved input data of daily surface meteorology and cloud-free FPAR in order to accurately monitor vegetation productivity in Korea.

• The Journal of Fisheries Business Administration
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• v.51 no.1
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• pp.37-52
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• 2020

The production of abalone seed has grown and been specialized since the 2000s with the growth of the abalone farming industry. Despite the increase in the production of abalone seeds, the sales volume of abalone seeds remained flat and competition among producers increased. This paper will analyze the management efficiency of abalone seed production fishery to diagnose the management status and improve the abalone seed production efficiency. In addition, this study is the result of the basic research on the abalone seed industry and it is meaningful to prepare a platform for further research since the management status survey and the management efficiency survey of abalone seed production fishery have not been conducted until now. The data on the farmed fish prices of abalone seeds were collected from surveys of sample fish as part of the fish seed observation project conducted by the Fisheries Outlook Center (FOC) of Korea Maritime and Fisheries Development Institute (KMI). Management efficiency analysis utilizes DEA (Data Envelopment Analysis) model. The DEA model was analyzed by classifying into CCR (Super-CCR), BCC, and SBM (Super-SBM) models according to the assumptions taking into account the characteristics of the industry. The slack considered in the SBM model was judged as possible decreases in input variables and increase in output variables. The average efficiency from the CCR model was analyzed to be 69%. The BCC model was classified into input and output orientations, and the average efficiency was 79% and 75%, respectively. There were seven production fisheries with an SE value of 1 or more, which remained unchanged in terms of size and could be benchmarked. The average efficiency of the SBM model was 59% for CRS and 66% for VRS. Under the VRS assumptions, the variable increase/decrease efficiency analysis shows that labor costs can be reduced by 37.3%, facility capacity by 18.8%, and operating costs by 8.5%. In order to improve management efficiency, Wando needs to reduce labor and management costs. In Jindo region, sales increase as well as labor cost reduction is urgent. In other regions, reduced facilities and increased sales are recommended.

• Management & Information Systems Review
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• v.35 no.4
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• pp.141-153
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• 2016

This study estimates the productivity change of pharmaceutical industry and decompose the change into technical efficiency change and technological change to explore ways to improve the productive efficiency. Unlike most previous studies, this study employs the non-radial and non-oriented slacks-based Malmquist productivity index which can deals directly with the input excesses and output shortfalls. In addition a smoothed bootstrap method is applied to estimate statistical confidence intervals for the Malmquist Index and its components. For the empirical analysis a balanced panel data set is constructed covering ten years over the period from 2005 to 2014. The input variables used in this study are number of workers, tangible assets and major production cost. The gross production is selected as a main output variable. The empirical results suggest that the productivity of pharmaceutical industry has decreased due mainly to decline in the technological progress rather than improvements in technical efficiency. An analysis result shows that the scale efficiency outweighs the pure efficiency in determining the technical efficiency of pharmaceutical industry. Therefore, in order to enhance the competitiveness of domestic pharmaceutical industry, it is important to continue supporting policies to promote the technology innovation capability through efficient R&D investment and industry reform strategy.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2615-2628
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• 1997

In this paper, a new codebook design algorithm is proposed. It uses a DCT map based on two-dimensional discrete cosine of transform (2D DCT) and finite state vector quantizer (FSVQ) when the vector quantizer is designed for image transmission. We make the map by dividing input image according to edge quantity, then by the map, the significant features of training image are extracted by using the 2D DCT. A master codebook of FSVQ is generated by partitioning the training set using binary tree based on tree-structure. The state codebook is constructed from the master codebook, and then the index of input image is searched at not master codebook but state codebook. And, because the coding of index is important part for high speed digital transmission, it converts fixed length codes to variable length codes in terms of entropy coding rule. The huffman coding assigns transmission codes to codes of codebook. This paper proposes single-side growing huffman tree to speed up huffman code generation process of huffman tree. Compared with the pairwise nearest neighbor (PNN) and classified VQ (CVQ) algorithm, about Einstein and Bridge image, the new algorithm shows better picture quality with 2.04 dB and 2.48 dB differences as to PNN, 1.75 dB and 0.99 dB differences as to CVQ respectively.

• Journal of Distribution Science
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• v.12 no.8
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• pp.5-15
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• 2014

Purpose - The method of TV home shopping is a kind of retail method that provides the viewer with information about products and, further, sells the products to consumers through the media of television. The domestic home-shopping industry has been expanding since 1995, and there are six companies in this arena as of 2012. In this study, we evaluate the management efficiency of TV home-shopping companies and provide suggestions for improving efficiency, using the DEA (data envelopment analysis) model. Hence, we expect to contribute to the progress of the companies' efficiency and the development of the TV home-shopping industry, where deepening competition is inevitable because it is experiencing the maturing market stage in its life cycle. Research design, data, and methodology - Efficiency is the ratio of the quantity of input to the quantity of output of a product or service. It is necessary to estimate aggregate inputs and aggregate outputs, which are calculated by applying a weighting to a number of input and output factors, to measure the efficiency. The DEA model is divided into the CCR model and the BCC model. The CCR model is a basic model that assumed constant returns to scale (CRS), and the BCC model extends the CCR model to accommodate technologies exhibiting variable returns to scale (VRS), and concerns only the technical efficiency without considering the efficiency of returns to scale. In this study, we consider six companies each year from 2008 to 2012 as a DMU (Decision Making Unit) and analyze the differences in efficiency for each company in each year. Furthermore, we evaluate the operating characteristics of TV home-shopping companies, using three models, in accordance with the overall performance, profitability, and marketability of the business. Results - The result of the analysis, using DEA models, shows that Hyundai Home Shopping (2009, 2010, 2011), GS Home Shopping (2011), NS Home Shopping (2011) and CJ O Shopping (2012) possess MPSS (most productive scale size), with a score 1.0 in CCR, BCC, and scale efficiency. Particularly, Hyundai Home Shopping is shown to be the most efficient in terms of overall business performance, marketability, and profitability. The overall efficiency of the home shopping industry has displayed an increasing trend since 2008, even though it decreased marginally in 2012; further, we can observe that home shopping companies operate with increasing efficiency with the passage of time. Conclusions - Home shopping companies have focused on market expansion rather than profits, as they displayed better efficiency in marketability than increase in profitability during the period 2008-2012. In addition, the main reason for the increased efficiency in the home shopping industry is the market expansion through the revenue increase of each home shopping company. This study can be used as a reference when home shopping companies attempt to devise future strategies, as it suggests efficiency benchmarks and development levels for each home shopping company.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.