• Communications for Statistical Applications and Methods
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• v.15 no.6
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• pp.909-923
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• 2008

This paper considers the replacement model and the preventive maintenance model following the expiration of combination warranty for a repairable system. If the system fails after the combination warranty is expired, then it is minimally repaired at each failure. The criterion used to determine the optimal replacement policy and the optimal preventive maintenance policy is the overall value function based on the expected cost rate per unit time and the expected downtime per unit time. The numerical examples are presented for illustrative purpose when the failure time follows a Weibull distribution.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.651-668
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• 2010

Various estimators of two risk measures of a specific financial portfolio, Value-at-Risk and Expected Shortfall, are compared for each case of 1-day and 10-day horizons. We use the Korea Composite Stock Price Index data of 20-year period including the year 2008 of the global financial crisis. Indexes of five foreign stock markets are also used for the empirical comparison study. The estimator considering both the heavy tail of loss distribution and the conditional heteroscedasticity of time series is of main concern, while other standard and new estimators are considered too. We investigate which estimator is best for the Korean stock market and which one shows the best overall performance.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.695-699
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• 2009

As a rule, when develop new product in company, multiple products that have similar function are developed simultaneously. These products are subjected to a group of tests covering quality, safety and durability. If the schedule of tests is changed, the expected net presented value(NPV) of new products is changed. The tests should be scheduled with the goal of maximizing the expected NPV of the new products. A model incorporated resource constraints with the sequencing of testing tasks of multiple products is proposed in this paper. Examples show that the proposed model can handle stochastic task duration data represented by scenarios with probabilities.

• Asia pacific journal of information systems
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• v.15 no.2
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• pp.171-193
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• 2005

Small firms are considered as the last mile in electronic networks of business enterprises. Since small firms lack in their resources and capabilities for IT deployment, it seems a challenging project to make them electronically linked to their trading partners. This study aims to investigate the factors that influence the intent of small firms to adopt electronic linkage to their trading partners. This study considers the context where small firms already have transaction relationships with partner firms and where their adoption of electronic linkage may influence the nature and performance of the transactional relationships. This study considers the expected value of electronic linkage and the joint actions of the trading firms as the major factors. Its research model also includes traditional factors such as influences from the industry and the trading partner, the support of CEO, and the readiness of the trading partner. Based on the survey data from more than 1000 small firms, the present study performs regression analysis and finds that all but one factor are significant in explaining the variations in the adoption intention of small firms. The exception is the joint action, which is shown to decrease the intention. Based on the results, this study offers business and policy implications that would be useful to business managers and policy makers.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.146-150
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• 2007

Extreme value distributions for new deep sea wave were analyzed by using spread parameter and correlations between spread parameter and sliding distance of caisson breakwater were shown in numerical example. When spread parameter is larger than as usual, there occurred extra-ordinarily large wave height among 50 annual maximum significant waves generated by extreme value distribution. Spread parameter of new design wave is identified to be comparably larger than some foreign coastal areas and may cause large sliding displacement though deterministic safety factor for sliding is satisfied with enough margin.

• The Journal of Fisheries Business Administration
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• v.25 no.2
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• pp.89-102
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• 1994

This paper is to survey the major results of the game-theoretic models and recent research directions of the literature on auctions and competitive biddings. This paper classifies the auctions and competitive biddings into the following four major types:(i) English auction, (ii) Dutch auction, (iii) the first-price sealed-bid auction, (iv) the second-price sealed-bid auction. In order to survey the major ideas related to auctions and competitive biddings, we use two representative theoretical models developed under the game-theoretic framework : (i) the independent private value model are summarized as follows ; (1) The Dutch auction and the first-price auction are strategically equivalent, and so are the English auction and the second-price auction. (2) At the symmetric equilibria, the expected selling price is the same for all four types of auction. Meanwhile, the major results of the general model are as follows ; (1) When bidders are uncertain about their value extimate, the English and second-price auctions are not equivalent, but the dutch and the first-price auctions are still strategically equivalent. (2) The English auction generates the higher expected prices than the second-price auction. Also, when bidders are risk-neutral, the second-price auction generated higher average prices than the Dutch and the first-price auctions.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.11-18
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• 2021

This paper shows the applicability of deep learning algorithm in predicting target position and getting correction value of impact point in order to improve the accuracy of naval gun firing. Predicting target position, the proposed model using LSTM model and RN structure is expected to be more accurate than existing method using kalman filter. Getting correction value of impact point, the another proposed model suggests a reinforcement model that manages factors which is related in ballistic calculation as data set, and learns using the data set. The model is expected to reduce error of naval gun firing. Combining two models, a ballistic calculation model for improving accuracy of naval gun firing based on deep learning algorithm was designed.

• The Korean Journal of Food And Nutrition
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• v.35 no.4
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• pp.231-238
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• 2022

As cholesterol intake increases, the prevalence of hypercholesterolemia is also increasing. With increasing food selection considering health, consumption of functional foods that can help health is also expected to increase. Ginger is rich in minerals (such as potassium and magnesium) and antioxidants. Antioxidants have been shown to be effective in lowering blood cholesterol levels. Therefore, we would like to produce madeleines helpful for hypercholesterolemia by adding ginger syrup to madeleines recently consumed as desserts. In this study, the quality and characteristics were analyzed after making madeleine by adding ginger syrup at 0%, 5%, 10%, 15%, and 20%. Baking loss was significantly reduced as the addition amount increased (p<0.001). The pH value decreased as the addition amount increased except for the 5% added group (p<0.001). The b value of the chromaticity showed a significant increase from the 5% addition group (p<0.001). Regarding textures, hardness (p=0.006), gumminess (p=0.001), and chewiness (p=0.001) all decreased as the addition amount increased. Regarding antioxidant activity, polyphenol, DPPH, and ABTS values were significantly increased as addition amount increased (p<0.001). Consequently, Madeleine using ginger syrup rich in antioxidants is expected to help health.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.3-10
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• 2022

An estimated investment gap of $176 billion needs to be filled over the next ten years to improve America's inland waterway transportation systems. Many of these infrastructure systems are now beyond their original 50-year design life and are often behind in maintenance due to funding constraints. Therefore, long-term maintenance strategies (i.e., asset management (AM) strategies) are needed to optimize investments across these waterway systems to improve their condition. Two common AM strategies include policy-driven maintenance and performance-driven maintenance. Currently, limited research exists on selecting the optimal AM approach for managing inland waterway transportation assets. Therefore, the goal of this study is to provide a decision model that can be used to select the optimal alternative between the two AM approaches by considering key uncertainties such as asset condition, asset test results, and asset failure. We achieve this goal by addressing the decision problem as a single-criterion problem, which calculates each alternative's expected value and certain equivalence using allocated monetary values to determine the recommended alternative for optimally maintaining navigable waterways. The decision model considers estimated and predicted values based on the current state of the infrastructure. This research concludes that the performance-based approach is the optimal alternative based on the expected value obtained from the analysis. This research sets the stage for further studies on fiscal constraints that will effectively optimize these assets condition.

• Journal of Distribution Science
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• v.22 no.4
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• pp.115-126
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• 2024

Purpose: This study aims to explore the citizens' perceptions of the smart city distribution strategy and its impact on quality of life, classifying generations into two groups: Generation X with Baby Boomers, and Millennials with Generation Z. This study formulated research questionsto explore how both generational groups perceive the impact of smart city experience, government's role, technology development, economic, social, and environmental factors, and institutional improvement on quality of life. Additionally, this study explored the influence of quality of life on city evaluation, life satisfaction, and the expected growth of the city. Research design, data and methodology: This study employed an online survey conducted by well-known research organization. This study utilized factor and regression analysis for data analysis. Results: This study revealed that the impact of smart city experience, technology development and social value on quality of life demonstrated significance in both generational groups. Additionally, the study identified significant results regarding the influence of quality of life on city evaluation, life satisfaction, and the expected growth of the city. Conclusions: The findings suggest that, for the development of smart cities, stakeholders should particularly consider economic value and environment aspects, as these factors ultimately impact on quality of life.