• The Journal of Fisheries Business Administration
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• v.43 no.2
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• pp.79-94
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• 2012

The purpose of this study is to investigate the production efficiencies of the Korean aquaculture fishery with respect to species and methods using a Data Envelopment Analysis. The study extracted the 8 fishes in each of the sea cage culture, aquarium basin, and enclosed aquaculture for the analytical purposes. First, the study estimated the technical, pure technical, and scale efficiencies of the total of 24 aquaculture fishes based on the traditional DEA under the assumptions of both CRS and VRS. 2 fishes were identified as the efficient DMUs under the CCR-model, and 6 fishes under the BCC-model. Second, we tested to see if there was any difference in production efficiencies regarding those three different methods of aquaculture. we could not find any evidence of the differences in efficiency using a rank sum test based on the traditional DEA. However, we could do find that the pure technical efficiency in the sea cage culture was lower than others at 1% level of significance and the pure technical efficiency in enclosed aquaculture was also lower than others at 5% level of significance using Bilateral-DEA, which could explicitly consider the heterogeneity in the 3 production methods of aquaculture. Finally, the study obtained the 95% confidence intervals of the efficiency scores for the 24 fishes under our study using the smoothed bootstraping method in the process of the re-sampling in cooperation with both a kernel density estimation and a reflection method. At the same time, we could estimate the bias-corrected efficiency scores while the traditionally estimated efficiency scores suffered from the biases in the process of solving a linear programming with the deterministic nature of a production frontier. And hence, we could distinguish the differences in production efficiencies of the 8 fishes with respect to those 3 methods of aquaculture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.101-109
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• 1993

On the basis of Nikuradse laboratory experiments. two transition flow regimes are defined with respect to the characteristics of boundary layer. One is the transitional turbulent flow which has a transitional characteristics between smooth turbulent flow and rough turbulent flow, and the other may be called as transitional laminar flow which has transitional features between laminar flow and turbulent flow. The laboratory results of Nikuradse are carefully re-examined, and the flow regions are clearly defined. The velocity profile of the transitional turbulent flow is described by newly formulated equation, and the Darcy-Weisbach friction coefficient for the transitional turbulent flow is determined based on the theoretical form of profile equation, which is far better accurate than Colebrook-White equation. Difficulties still arise for the description of velocity profile when the flow undergoes from laminar to turbulent. In this case a linear interpolation procedure is proposed for the estimation of friction coefficient.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.2
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• pp.101-113
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• 2003

Nowadays, the construction of new ground structures, which can influence the stability of existing underground structures, is increasing. Consequently, many technical problems occur during the design and construction stage of the new structures. In constructing a neighboring structure, reasonable design and construction is strongly required to balance between the stability of the existing underground structures and the economy of construction of the new structure in terms of the importance of the existing underground structures. Many researches have been performed to estimate the safe region and behavior of underground structures. Constructing a new ground structure above the existing underground structure, external loads are to be applied to the existing underground structure. In this study, therefore, the stability and safe region of the existing underground structure was re-established with respect to the relative location of the new ground structure with the underground structure, the depth from surface to top of the underground structures, and ground conditions.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.94-99
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• 1999

It is the hybrid structure of HMM and neural network(NN) that shows high recognition rate in speech recognition algorithms. And it is a method which has majorities of statistical model and neural network model respectively. In this study, we propose a new style of the hybrid structure of semi-continuous HMM(SCHMM) and radial basis function(RBF), which re-estimates weighting coefficients probability affecting observation probability after Baum-Welch estimation. The proposed method takes account of the similarity of basis Auction of RBF's hidden layer and SCHMM's probability density functions so as to discriminate speech signals sensibly through the learned and estimated weighting coefficients of RBF. As simulation results show that the recognition rates of the hybrid structure SCHMM/RBF are higher than those of SCHMM in unlearned speakers' recognition experiment, the proposed method has been proved to be one which has more sensible property in recognition than SCHMM.

• STI Policy Review
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• v.4 no.2
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• pp.41-54
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• 2013

R&D is inherently an uncertain endeavor, yet now more than ever those performing R&D with public funding are called upon to clarify the utility of their research. Calls for public accountability are mounting with the increase in constraints on government budgets due to the recent worldwide economic recession, in response to which both policymakers and researchers pay much more attention to rigorously assessing publicly funded R&D. A key issue complicating R&D evaluation in these circumstances is how to adequately account for the nature and degree of risk involved in a given R&D program or project. This study deliberates on certain issues involving the measurement of ex-ante risk in public R&D evaluation: (i) information asymmetry between R&D sponsors and performers, (ii) ambiguity in the measurement of returns in both prospective and retrospective evaluation, and (iii) the dilemma between measurement error and omitted variable bias for empirical estimation of R&D performance. The study then presents an analysis of hypothetical evaluation results that apply risk-relevant weights to the annual evaluation outcomes of South Korea's national R&D programs funded during 2006~2012. In this counterfactual re-evaluation of public R&D program performance, high-risk R&D programs turn out to receive higher evaluation than non-high-risk programs. The current study suggests that R&D evaluation ignoring ex-ante risk is not only conceptually invalid since R&D activities are intrinsically uncertain endeavors, but unfair as R&D performers are asked to be accountable for the results that were in fact out of their reach.

• Journal of Korean Society for Quality Management
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• v.48 no.3
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• pp.493-510
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• 2020

Purpose: As of July 31, there were 14,336 confirmed cases of COVID-19 in South Korea, including 301 deaths. Since the daily confirmed number of cases hit 909 on February 29, the spread of the disease had gradually decreased due to the active implementation of preventive control interventions, and the daily confirmed number had finally recorded a single digit on April 19. Since May, however, the disease has re-emerged and retaining after June. In order to eradicate the disease, it is necessary to suggest suitable forward preventive strategies by predicting future infectivity of the disease based on the cases so far. Therefore, in this study, we aim to evaluate the transmission potential of the disease in early phases by estimating basic reproduction number and assess the preventive control measures through effective reproduction number. Methods: We used publicly available cases and deaths data regarding COVID-19 in South Korea as of July 31. Using ensemble model integrated stochastic linear birth model and deterministic linear growth model, the basic reproduction number and the effective reproduction number were estimated. Results: Estimated basic reproduction number is 3.1 (95% CI: 3.0-3.2). Effective reproduction number was the highest with 7 on February 15, decreased as of April 20. Since then, the value is gradually increased to more than unity. Conclusion: Preventive policy such as wearing a mask and physical distancing campaigns in the early phase of the outbreak was fairly implemented. However, the infection potential increased due to weakening government policy on May 6. Our results suggest that it seems necessary to implement a stronger policy than the current level.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.49-55
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• 2010

Safety estimation of the pillar between parallel tunnels are very important considering stress concentration in case the piller width is not enough to secure the stability. Pillar width needs to be determined properly because of the progressive failure-risk of pillar due to stress-concentration. In this research, the effect of element size in numerical analysis was evaluated based on that yield pillar's stability and proposed systematic analysis about pilar's stability examination. In consequence of it, element size does not give any effect on intensity stress ratio. On the other hand, the analysis using the smaller element size results in lower safety factor in strength reduction technique. In case of the weathered re.k on the main ground layer, the analysis of result was not reliable. In conclusion, the smaller element size is, the more stable factor is.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.175-180
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• 2006

Total conceptual cost estimates and the assessment of the reliability of these estimates are critical in the early stages of a building construction project. The purpose of this study is to propose the method to clients or estimators for improving the reliability of conceptual cost estimates by evaluating the reliability of conceptual cost estimates. The data from 83 building construction projects were collected for this study. The results showed that the proposed method can propose alternatives to clients or estimators for improving the reliability of conceptual cost estimates with the process of evaluation, review and feedback. This process can assist clients in their evaluation of the reliability of the estimated cost and the probability of exceeding the target cost, and in their re-estimation after dealing with the elements that influence the conceptual cost estimate badly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9C
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• pp.761-770
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• 2010

In this paper, we propose a new Frame Rate Up-Conversion (FRUC) scheme to increase the frame rate from a lower number into a higher one and enhance the decoded video quality at the decoder. The proposed algorithm utilizes the preliminary frames of forward and backward direction using bilateral prediction. In the process of the preliminary frames, an additional interpolation is performed for the occlusion area because if the calculated value of the block with reference frame if larger than the predetermine thresholdn the block is selected as the occlusion area. In order to interpolate the occlusion area, we perform re-search to obtain the osiomal block considerhe osiomnumber of available ne block consblock. The experimental results show that performance of the proposed algorithm has better PSNR and visual quality than the conventional methods.

• Environmental and Resource Economics Review
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• v.18 no.2
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• pp.345-375
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• 2009

In this paper we examined the impact of mineral resources industry on the national economy and necessity of a mineral resources cycle technology development. For this purpose, the case study on Gagok polymetallic (zinc-lead-copper) mine, which is being re-developed, was carried out to study an anticipated effects of application of the full cycle technology. As a consequences of the study, if we apply the technology to a polymetallic (zinc-lead-cooper) mine, we can expect 55 billion won worth of import-substitution effect. Moreover, if applied to 10 similar mines, we can expect the 10.4% of import-substitution effect of the total imports annually. Also, national competitiveness in value chain of mineral industry will be promoted through the technological advancement in upper stream and the full cycle technology will render a service to the mineral industry to be the country's new growth engine.