• International Journal of Reliability and Applications
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• v.4 no.4
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• pp.171-181
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• 2003

This paper proposes a U-test statistic for the problem of testing that a life distribution is exponential against the alternative that it is harmonic new better (worse) than used in expectation upper tail HNBUET (HNWUET), but not exponential on complete data. Selected critical values are tabulated for sample sizes n =5(1)60. The asymptotic normality of the statistic is proved and a comparison is made of the asymptotic efficiency between the statistic and other statistics. The power of the test is studied by simulation. A test for HNBUET in the case of randomly right-censored data is also considered. An application of the proposed test statistic in medical sciences is given.

• Nuclear Engineering and Technology
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• v.34 no.1
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• pp.68-79
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• 2002

The approach for evaluating the critical heat flux (CHF) margin using the departure from nucleate boiling ratio (DNBR) concept has been widely applied to PWR core design, while DNBR in this approach does not indicate appropriately the CHF margin in terms of the attainable power margin-to-CHF against a reactor core condition. The CHF power margin must be calculated by increasing power until the minimum DNBR reaches a DNBR limit. The Critical Power Ratio (CPR), defined as the ratio of the predicted CHF power to the operating power, is considered more reasonable for indicating the CHF margin and can be calculated by a CPR orrelation based on the heat balance of a test bundle. This approach yields directly the CHF power margin, but the calculated CPR must be corrected to compensate for many local effects of the actual core, which are not considered in the CHF test and analysis. In this paper, correction of the calculated CPR is made so that it may become equal to the DNB overpower margin. Exemplary calculations showed that the correction tends to be increased as power distribution is more distorted, but are not unduly large.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.508-513
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• 1997

One of the moot important constants to be Installed In COLSS, a monitoring system in CE typed reactors, is ROPM which would limit the operating space. This static ROPM was calculated from digital transient analysis assuming that every design basis transient was initiated from the most severe initial condition combination (LCO). Once It could be assured that core condition would not be located at none other than LCO, this static ROPM could be replaced with dynamic ROPM calculated at that condition and the dynamic ROPM would be definitely less than the static ROPM. In order to do, It must be required to calculate the transient discrete sensitivity parameters and parameters change distribution. The purpose of this report is just to propose the enlargement method for thermal margin.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.1-7
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• 2018

Objective signs are everywhere that the stationary energy storage market is growing up quickly. The use of distributed resources such as solar photovoltaics and electric vehicles are expanding at a rapid pace, creating technical challenges for the distribution system that will require energy storage and a new generation of software to address. This paper is intended for distribution utility managers and executives and makes the following points: ${\bullet}$ Utility-integrated (as opposed to merely grid-connected) energy storage projects represent a distinct, new wave of industry growth that is just getting underway and is required to manage distributed energy resources moving forward. ${\bullet}$ Utilities and the energy storage industry have important roles to lower risk in adopting this technology - thereby enabling this wave of growth. ${\circ}$ The industry must focus on engineering energy storage for adoption at scale - including the creation and support of software open standards -both to drive down costs and to limit technology and supplier risk for utilities. ${\circ}$ Utilities need to take a program-based, rather than a project- based, approach to this resource to best balance cost and risk as they procure and implement energy storage. By working together to drive down costs and manage risk, utilities and their suppliers can lay the energy storage foundation for a new, more digital distributed electricity system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.849-856
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• 2009

Truncal obesity associated with insulin resistance and metabolic syndrome increase the likelihood of hypertension, various cardiovascular diseases, hyperlipidemia and coronary heart diseases. International Diabetes Federation (IDF) experts recognized that it is necessary to develop the simple diagnostic tool which is applicable to diagnose truncal obesity worldwide, and proposed the method using a waist circumference but there is a limit to estimate subcutaneous fat distribution. However, waist line is also influenced by total fat capacity less than the intra abdominal fat. The more having severe obesity, the more correlation coefficient between waist line and intra abdominal fat is low. Therefore, this thesis defines a new abdominal impedance measurement position and impedance-index to analysis central obesity. This proposes the new model to estimate abdominal obesity using the abdominal impedance-index and CT images acquired fro 160 Korean subjects. The proposed model shows that the abdominal fat distribution has a higher correlation than waist line. (Adj R2=0.809, 0.667 and 0.687 with abdominal fat area, visceral fat area and subcutaneous fat area respectively).

• Structural Engineering and Mechanics
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• v.49 no.3
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• pp.285-296
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• 2014

Material damping affects the dynamic behaviors of engineering structures considerably, but up to till now little research is maintained on influence factors of material damping. Based on the damping-stress function of steel, the material damping of steel beams is obtained by calculating the stress distribution of the beams with an analytical method. Some key influence factors of the material damping, such as boundary condition, amplitude and frequency of excitation, load position as well as the cross-sectional dimension of a steel beam are analyzed respectively. The calculated results show that even in elastic scope, material damping does not remain constant but varies with these influence factors. Although boundary condition affects material damping to some extent, such influence can be neglected when the maximum stress amplitude of the beam is less than the fatigue limit of steel. Exciting frequency, load position and cross-section dimension have great effects on the material damping of the beam which maintain the similar changing trend under different boundary conditions respectively.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.1
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• pp.7-12
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• 2006

This paper proposes the new voltage event detection method using the weight factor of neural network and describes control system design for the DVR(Dynamic Voltage Restorer) consisted of a rectifier and series inverter applied to 22.9kV distribution system. As this method can express the fault level of each phase, we expect the proposed method can make up for disadvantage of synchronous detection method. Also, in this paper, the control system was designed using double deadbeat controller, As it has an inner current control loop and an outer voltage control loop, we can easily limit the current level during the transient intervals by using the current control loop. Simulation and experiment are performed to prove the analysis of the voltage event detection method and double deadbeat controller.

• Industrial Engineering and Management Systems
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• v.13 no.2
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• pp.129-147
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• 2014

This study proposes an optimal operational policy for a green supply chain (GSC) where a retailer pays an incentive for collection of used products from customers and determines the optimal order quantity of a single product under uncertainty in product demand. A manufacturer produces the optimal order quantity of product using recyclable parts with acceptable quality levels and covers a part of the retailer's incentive from the recycled parts. Here, two scenarios for the product demand are assumed as: the distribution of product demand is known, and only both mean and variance are known. This paper develops mathematical models to find how order quantity, collection incentive of used products and lower limit of quality level for recycling affect the expected profits of each member and the whole supply chain under both a decentralized GSC (DGSC) and an integrated GSC (IGSC). The analysis numerically compares the results under DGSC with those under IGSC for each scenario of product demand. Also, the effect of the quality of the recyclable parts on the optimal decisions is shown. Moreover, supply chain coordination to shift the optimal decisions of IGSC is discussed based on: I) profit ratio, II) Nash bargaining solution, and III) Combination of (I) and (II).

• Geomechanics and Engineering
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• v.17 no.5
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• pp.439-444
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• 2019

It is generally known that high strength soil is indicative of well-graded particle size distribution. However, there are some special cases of firm ground despite poor grade distribution, especially a specific gap-graded soil. Based on these discoveries, this study investigated the development of an additive of gap-graded soils designed to increase soil strength. This theoretical concept was used to calculate the mixed ratio required for optimal soil strength of the ground sample. The gap-graded aggregate was added according to Plato's polyhedral theory and subsequently calculated ratio and soil strength characteristics were then compared to characteristics of the original soil sample through various test results. In addition, the underground stress transfer rate was measured according to the test conditions. The test results showed that the ground settlement and stress limit thickness were reduced with the incorporation of gap-graded soil. Further field tests would confirm the reproducibility and reliability of the technology by using gap-graded soil to reinforce soft ground of a new construction site. Gap-graded soil has the potential to reduce the construction cost and time of construction compared to other reinforcing methods.

• Korean Journal of Organic Agriculture
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• v.6 no.1
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• pp.63-75
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• 1997

This study aims to find out the devices to minimize the amount of nitrate ingested from kimchi, the main way of vegetable intake for Koreans, and the basic data to deliver to calculate the total daily intake for Korean, investigating the year-round changes of nitrate content in vegetables for Kimche raw material, and changes of nitrate content by salting of chinese cabbage, and stewed kimchi through the use of different cooking methods. The results obtained were summarized as follow: over between 205-6655mg/kg f.w. in chinese cabbage, 480-3970mg/kg f.w. in chinese radish, 157-5820mg/kg f.w. in lettuce and 29-520mg/kg f.w. in cucumber respectively. Therefore it was strongly adviced to introduce the nitrate limit value of vegetables in Korea if the nitrate content in Kimchi should be reduced to meet the nitrate ADI(Acceptable Daily Intake, 219mg60kg b.w) of FAO.WHO, because the nitrate content in Kimchi reflects the nitrate content in vegetables. In order to keep the low nitrate content in Kimchi. it was adviced to remove the outer leaf which contains 2-3 times higher nitrate content compare to the inner leaf at the time of preparation, i.e. chinese cabbage, before the soaking treatment in salt solution for Kimchi making process. The dehydration by soaking treatment in salt solution occurred at 0.9%~4.7% in leaf midrib and more than 13%~24% in leaf blade. The nitrate content after soaking in salt solution was increased 107%~123% compared with before soaking, increasing rates of nitrate content in the outer and inner leaf midrib were higher than those in leaf blade. The increase of nitrate content in salt solution after soaking due to the dehydration of chinese cabbage by soaking treatment. The Kimchi stew(Kimchi JJige) was processed with and without animal oil, but the amount of nitrate in kimchi stew did not decrease both treatments, but it increased after the processing since the water in Kimchi stew has got low by boiling.