• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.105-111
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• 2017

Vendor Managed Inventory is a well-known vendor-retailer coordination approach in supply chain management where the vendor manages inventory of the retailer and determines the order interval and order quantity for the retailer. To consider practical situation, the upper limit of inventory for the retailer is set. If the inventory level for the retailer exceeds the upper limit, then the penalty cost is charged to the retailer. Furthermore, maximum allowable inventory level is set for the vendor to prevent the vendor from keeping much inventory. Single-vendor multi-retailer supply chain model with upper limit of inventory for vendor and retailers is studied. All the retailers' are assumed to have the common cycle time, and a vendor manages retailers' inventory and replenishes products. The mathematical formulation is introduced to minimize the total cost including the penalty cost violating the upper limit of inventory for retailers with the constraint of maximum allowable inventory level. The solution procedure based on Karush-Kuhn-Tucker (KKT) conditions is derived. KKT conditions are often applied to find an optimal solution of nonlinear programming problem with constraints. An illustrative example is used to show the application of the proposed solution procedure. Furthermore, sensitivity analysis is done to find out the relationship between maximum allowable inventory level and other values such as order quantity, the number of shipment, vendor's cost, retailer's cost, and total cost. As maximum allowable inventory level decreases, the number of shipment decreases but total cost increases. Order quantity has the trend of decline and is affected by the number of shipment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.1
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• pp.34-43
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• 2016

Urban development and population increases are continuously progressed in the coastal areas in Korea, thus it is expected that vulnerability towards coastal disasters by sea level rise (SLR) would be accelerated. This study investigated trend of the sea level data using Mann-Kendall (MK) test, and the results showed that the increasing trends of annual average sea level at 17 locations were statistically significant. For annual maximum extremes, seven locations exhibited statistically significant trends. In this study, non-stationary frequency analysis for the annual extreme data together with average sea level data as a covariate was performed. Non-stationary frequency analysis results showed that sea level at the coastal areas of Korean Peninsula would be increased from a minimum of 60.33 mm to a maximum of 214.90 mm by 2100.

• Journal of Coastal Disaster Prevention
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• v.4 no.3
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• pp.119-131
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• 2017

Global warming under the influence of climate change and its direct impact on glacial and sea level are known issue. However, there is a lack of research on an indirect impact of climate change such as coastal structure design which is mainly based on a frequency analysis of water level under the stationary assumption, meaning that maximum sea level will not vary significantly over time. In general, stationary assumption does not hold and may not be valid under a changing climate. Therefore, this study aims to develop a novel approach to explore possible distributional changes in annual maximum sea levels (AMSLs) and provide the estimate of design water level for coastal structures using a multiple non-crossing quantile regression based nonstationary frequency analysis within a Bayesian framework. In this study, 20 tide gauge stations, where more than 30 years of hourly records are available, are considered. First, the possible distributional changes in the AMSLs are explored, focusing on the change in the scale and location parameter of the probability distributions. The most of the AMSLs are found to be upward-convergent/divergent pattern in the distribution, and the significance test on distributional changes is then performed. In this study, we confirm that a stationary assumption under the current climate characteristic may lead to underestimation of the design sea level, which results in increase in the failure risk in coastal structures. A detailed discussion on the role of the distribution changes for design water level is provided.

• Journal of Families and Better Life
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• v.21 no.2
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• pp.155-173
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• 2003

The purpose of this study was to gain an understanding about urban housewives' stress in family financial management, their coping strategies, and their sense of economic well-being, which will eventually provide some baseline data for policy development. The findings of this study are summarized in the following. First, the mean score of the level of financial management-related stress among urban housewives was 2.61 when the maximum level was set at 5. In order to overcome the stress from financial management, housewives utilized various strategies, such as purchasing management, financial planning, financial information gathering, getting a loan, and delaying payments. The average level of economic well-being among urban housewives was 2.82 when the maximum level was 5. Second, among socio-demographic factors, the family's monthly income and the husband's job satisfaction were the two most significant factors that affected the level of financial management stress among housewives. Third, there was a difference in employing coping strategies according to the level of stress. The group with a higher level of financial stress employed more coping strategies than the group with, a lower level of stress. Fourth, there were differences in the level of economic well-being, depending on the types of coping strategies employed. Fifth, the results from regression analyses, which were conducted to determine the relative explanatory power of different independent variable groups including subjective factors, financial management stress, and coping strategies, showed that socio-demographic and objective economic factors significantly affected economic well-being.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1598-1611
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• 2016

In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.3-8
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• 2013

Recently, the impact on hearing induced by using of portable audio equipment have been actively studied. In general, Because they turn the volume up with loud background noise, they may expose to louder noise. In this study, we investigated the maximum noise level of 20 the domestic potable audio equipment and estimated the impact of the hearing induced by portable audio equipment in according to exposure time. As a result, the use of portable audio equipment is assumed to be more three hours when the level of more than 50 % of volume is most likely to affect the hearing.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.77-80
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• 2000

In this paper, we present a new automatic thresholding algorithm based on maximum entropy of two-dimensional pixel histogram. While most of the previous algorithms select thresholds depending only on the histogram of gray level itself in the image, the presented algorithm considers 2D relational histogram of gray levels of two adjacent pixels in the image. Thus, the new algorithm tends to leave salient edge features on the image after thresholding. The experimental results show the good performance of the presented algorithm.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.700-703
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• 2004

The purpose of this study is to present the design methodology of base isolated buildings. To achieve the goal of this study, time-history analysis was performed with seismic performance level and recorded seismic data. From the analysis results of MDOF system, the maximum. displacement and base shear were evaluated as 25 cm and $4\%$ by the input level which is maximum velocity of 50 kine. By introducing hybrid isolation system, seismic energy can be concentrated consequently high seismic capacity of the total building is secured.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.88-95
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• 2000

The level of noise produced by machinery and its arrangement insides a factory is indicated to be a maximum of 96.1 dB(A). The maximum level of noise from a commoner's house outside the factory is shown to be 62.9 dB(A), which exceeds 60 dB(A), the permitted limit of noise level in a time period of day. us study has predicted the level of noise reduction according to a step by step prevention plan by considering the characteristics of the causes of noise, the permitted limit of noise levels, problems and economical efficiency attendant upon the noise prevention measures. Establishing target levels of noise each of the three steps of the noise prevention plan. The predicted level of noise at the place of a commoner's house in accordance with the first step is 50.0 - 59.0 dB(A), and can satisfy the permitted limit of noise in a time period of the day. In taking prevention measures for the second step, the noise level is 50.7 - 53.6 dB(A) which is less than 55 dB(A) in a time period of the evening, the permitted limit of noise in a time period of night., and it can meet 47.4 - 50.3 dB(A) in the third step.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.1
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• pp.22-30
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• 1999

This paper presents an efficient algorithm to estimate the maximum load level for heavily loaded power systems with the load-generation vector obtained by ELD (Economic Load Dispach) and/or short term load forecasting while utilizing the elliptic pattern of the P-e curve. It is well known the power flow equation in the rectangular corrdinate is jully quadratic. However, the coupling between e and f makes it difficult to take advantage of this quadratic characteristic. In this paper, the elliptic characteristics of P-e curve are illustrated and a simple technique is proposed to reflect the e-f coupling effects on the estimation of maximum loadability with theoretical analysis. An efficient estimation algorithm has been developed with the use of the elliptic properties of the P-e curve. The proposed algorithm is tested on IEEE 14 bus system, New England 39 bus system and IEEE 118 bus system, which shows that the maximum load level can be efficiently estimated with remarkable improvement in accuracy.