• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.1
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• pp.28-35
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• 2006

An accurate prediction of budburst in grapevines is indispensable for vineyard frost warning system operations in spring because cold tolerance depends heavily on phonology. However, existing frost warning systems utilize only daily minimum temperature forecasts since there is no way to estimate the site-specific phonology of grapevines. A budburst estimation model based on thermal time was used to project budburst dates of two grapevine cultivars (Kyoho and Campbell Early), and advisories were issued depending on phonology as well as temperature. A 'warning' is issued if two conditions are met: the forecasted daily minimum temperature falls below $-1.5^{\circ}C$ and the estimated phonology is within the budburst period. A 'watch' is issued for a temperature range of -1.5 to $+1.5^{\circ}C$ with the same phonology condition. Validation experiments were done at 8 vineyards in Anseong in spring 2005, and the results showed a good agreement with the observations. This method was applied to the climatological normal year (1971-2000) to determine sites with high frost risk at a 30 m grid cell resolution. Among 608,585 grid cells constituting Anseong, 1,059 cells were identified as high risk for growing Kyoho and 2,788 cells for Campbell Early.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.207-216
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• 2000

This paper introduces an effective system design method to develop a customer oriented product using a design optimization process and to select a set of critical design paramenters,. The process results in the development of a successful product satisfying customer needs and reducing development risk. The proposed scheme adopted a five step QFD(Quality Function Deployment) in order to extract design parameters from customer needs and evaluated their priority using risk factors for extracted design parameters. In this process we determine critical design parameters and allocate them to subsystem designers. Subsequently design engineers develop and test the product based on these parameters. These design parameters capture the characteristics of customer needs in terms of performance cost and schedule in the process of QFD, The subsequent risk management task ensures the minimum risk approach in the presence of design parameter uncertainty. An application of this approach was demonstrated in the development of weld quality monitoring system. Dominant design parameters affect linearity characteristics of weld defect feature vectors. Therefore it simplifies the algorithm for adopting pattern classification of feature vectors and improves the accuracy of recognition rate of weld defect and the real time response of the defect detection in the performance. Additionally the development cost decreases by using DSP board for low speed because of reducing CPU's load adopting algorithm in classifying weld defects. It also reduces the cost by using the single sensor to measure weld defects. Furthermore the synergy effect derived from the critical design parameters improves the detection rate of weld defects by 15% when compared with the implementation using the non-critical design parameters. It also result in 30% saving in development cost./ The overall results are close to 95% customer level showing the effectiveness of the proposed development approach.

• International Area Studies Review
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• v.13 no.2
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• pp.505-523
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• 2009

We study the cost of capital of Islamic enterprise using the Capital Asset Pricing Model(CAPM). When there exists no risk-free interest rate, the security market line(SML) of Islamic enterprise shows an upward slope starting from the origin. The slope is bigger than that of SML with risk-free interest rate. This is because the cost of capital of Islamic enterprise is higher than that of western firms for the same level of systematic risk. When the effect of zakat is considered, the risk-free interest rate is replaced by minimum required rate of return. The SML of Islamic enterprise reveals an upward slope but it does not pass through the origin. This is because Islamic enterprise cannot invest on risk-free asset. In order to overcome the theoretic limits of CAPM, we propose to use multi-factor approach such as arbitrage pricing model instead of single-factor model for future study.

• Korea Trade Review
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• v.46 no.2
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• pp.19-38
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• 2021

This study aims to analyze the foreign asset leverage effect on Korean oil & gas companies' foreign profits and to maintain the appropriate foreign asset volume for reducing exchange risk. For a long time, large Korean companies, including oil companies, overheld foreign currency liabilities. For this reason, most large companies have been burdened to hedge exchange risk and this excess limit holding deteriorated total profit and reduced foreign currency asset management efficiency. Our paper proceeds in presenting a three-stage analysis considering diversified exchange risk factors through estimation on transformation of foreign transactions a/c including annual trends of foreign asset and industry specifics. We also supplement incomplete the estimation method through a practical hedging case investigation. Our research parts are differentiated on the analyzing four periods considering period-specifics The FER value of the oil firms ranged from -0.3 to +2.3 over the entire period. The results of the FER Value are volatile and irregular; those results do not represent the industry standard comparative index. The Korean oil firms are over the credit limit without accurate prediction and finance high interest rate funds from foreign-owned banks on the basis on a biased relationship. Since the IMF crisis, liabilities of global firms have decreased. Above all, oil firms need to finance a minimum limit without opportunity losses on the demand forecast and prepare for uncertainty in the market. To reduce exchange risk from the over-the-limit position, we must consider factors that affect the corporate exchange risk on the entire business process, including the contract phase.

• Journal of the Korean earth science society
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• v.31 no.5
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• pp.437-447
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• 2010

Spatial estimation of environmental variables has been regarded as an important preliminary procedure for decision-making. A minimum variance criterion, which has often been adopted in traditional kriging algorithms, does not always guarantee the optimal estimates for subsequent decision-making processes. In this paper, a geostatistical framework is illustrated that consists of uncertainty modeling via stochastic simulation and risk modeling based on loss functions for the selection of optimal estimates. Loss functions that quantify the impact of choosing any estimate different from the unknown true value are linked to geostatistical simulation. A hybrid loss function is especially presented to account for the different impact of over- and underestimation of different land-use types. The loss function-specific estimates that minimize the expected loss are chosen as optimal estimates. The applicability of the geostatistical framework is demonstrated and discussed through a case study of copper mapping.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.403-411
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• 2011

This paper deals with a group acceptance sampling plan for time truncated tests which are based on the total number of failures from the whole group assuming that the life time of an item follows the Dagum (inverse Burr) distribution. This study is developed when a multiple number of items as a group can be tested simultaneously in a tester. The minimum number of groups required for a given group size and acceptance number is determined such that the producer and consumer risks are satisfied simultaneously at the specified quality level, while the termination time and the number of testers are specified. Comparisons are made between the proposed plan and the existing plan on the basis of size of the groups. Two real examples are provided.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.393-395
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• 2006

In competitive market, it is important to establish a plan of transmission expansion considering uncertainty of future generation and load behavior. For this reason, revised transmission expansion model is proposed in this paper. In the proposed model, information of predictable future condition are included in a cost function of transmission expansion investment. Also, to reduce risk of the investment, mean-variance Markowitz approach is added to the objective function of cost. By optimization programming, the most robust and the minimum cost plan can be obtained.

• Journal of the Korea Safety Management & Science
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• v.9 no.2
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• pp.123-134
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• 2007

This paper focuses on the in-house reliability assurance plan for the bulk materials of each company. The reliability assurance needs in essence a long time and high cost for testing the materials. In order to reduce the time and cost, accelerated life test is adopted. The bulk sampling technique was used for acceptance. Design parameters might be total sample size(segments and increments}, stress level and so on. We focus on deciding the sample size by minimizing the asymptotic variance of test statistics as well as satisfying the consumer's risk. In bulk sampling, we also induce the sample size by adapting the normal life time distribution model when the variable of the lognormal life time distribution is transformed and adapted to the model. In addition, the sample size for both the segments and increments can be induced by minimizing the asymptotic variance of test statistics of the segments and increments with consumer's risk met. We can assure the reliability of the mean life and B100p life time of the bulk materials by using the calculated minimum sample size.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.91-95
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• 2014

During a flood season, Bo region could be easily exposed to flood due to increase of ground water level and the water drain difficulty even the water amount of Bo can be managed. GFI for the flood risk is measured by mean depth to water during a dry season and minimum depth to water and tangent degree during a flood season. In this paper, a forecasting model of the target variable, GFI and predictors as differences of height between ground water and Bo water, distances from water resource, and soil characteristics are obtained for the dry season of 2012 and the flood season of 2012 with empirical data of Gangjungbo and Hamanbo. Obtained forecasting model would be used for keep the value of GFI below the maximum allowance for no flooding during flooding seasons with controlling the values of significant predictors.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1248-1251
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• 2011

Web Service technologies make the automation of business activities that are distributed across multiple enterprises possible. Existing extended transaction protocols typically resort to compensation actions to regain atomicity and consistency. A reservation-based transaction protocol is proposed to reduce high compensation risk. However, for a serial long running transaction processing, the resource that is reserved in the early stage may be released due to resource holding time expires. Therefore, our analysis theoretically illustrates a scheduling scheme that tries to prevent the loss of resource holding as well as gain an optimized execution plan with minimum compensation cost. In order to estimate cost of different schedules, we set up a costing model and cost metric to quantize compensation risk.