• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1158-1167
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• 1995

In this study, the dynamic instabilities of a beam, subjected to periodic short impulsive loading, are investigated using simple 2-DoF beam model. The behaviors of beam model whose axial motions are constrained are studied for the case of elastic and elastic-plastic behavior. In the case of elastic behavior, the chaotic responses due to the periodic pulse are identified, and the characteristics of the behavior are analysed by investigating the fractal attractors in the Poincare map. The short-term and long-term responses of the beam are unpredictable because of the extreme sensitivities to parameters, a hallmark of chaotic response. In the case of elastic-plastic behavior, the responses are governed by the plastic strains which occur continuously and irregularly as time increases. Thus the characteristics of the response behavior change continuously due to the plastic strain increments, and are unpredictable as well as the elastic case.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.229-234
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• 2001

A practical and effective semi-active on-off control law is developed for vibration attenuation of a natural, multi-degree-of-freedom suspension system, when its operational response mode is available. It does not need the accurate system parameters and dynamics of semi-active actuator. It reduces the total vibratory energy of the system including the work done by external disturbances and the maximum energy dissipation direction of the semi-active control device is tuned to the operational response mode of the structure. The effectiveness of the control law is illustrated with a three degree-of-freedom excavator cabin model.

• Analytical Science and Technology
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• v.12 no.6
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• pp.490-497
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• 1999

A hydrogen determinator was modified and installed in the glove box to analyse total hydrogen content in irradiated zircaloy tube. The analysis method of hydrogen is Inert Gas Fusion(IGF)-Thermal Conductivity Detection(TCD). The hydrogen recoveries of no tin method using Ti and Zr matrix standards, respectively, were available within $3{\mu}g$ of hydrogen. Also the smaller size of sample showed the better hydrogen recovery. It was found that the hydrogen standard of Ti matrix is avaliable to hydrogen analysis in zircaloy sample. The mean radioactivity of irradiated zircaloy sample was 10 mR/hr and hydrogen concentration was 130 ppm.

• Advances in Energy Research
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• v.7 no.1
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• pp.67-84
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• 2020

Given the recent surge of interest towards utilization of renewable distributed energy resources (DER), in particular in remote areas, this paper aims at designing an optimal hybrid system in order to supply loads of a village located in Esfarayen, North Khorasan, Iran. This paper illustrates the optimal design procedure of a standalone hybrid system which consists of Wind Turbine Generator (WTG), Photo Voltaic (PV), Diesel-generator, and Battery denoting as the Energy Storage System (ESS). The WTGs and PVs are considered as the main producers since the site's ambient conditions are suitable for such producers. Moreover, batteries are employed to smooth out the variable outputs of these renewable resources. To this end, whenever the available power generation is higher than the demanded amount, the excess energy will be stored in ESS to be injected into the system in the time of insufficient power generation. Since the standalone system is assumed to have no connection to the upstream network, it must be able to supply the loads without any load curtailment. In this regard, a Diesel-Generator can also be integrated to achieve zero loss of load. The optimal hybrid system design problem is a discrete optimization problem that is solved, here, by means of a recently-introduced meta-heuristic optimization algorithm known as Lightning Attachment Procedure Optimization (LAPO). The results are compared to those of some other methods and discussed in detail. The results also show that the total cost of the designed stand-alone system in 25 years is around 92M€ which is much less than the grid-connected system with the total cost of 205M€. In summary, the obtained simulation results demonstrate the effectiveness of the utilized optimization algorithm in finding the best results, and the designed hybrid system in serving the remote loads.

• Rapid Communication in Photoscience
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• v.3 no.1
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• pp.25-27
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• 2014

The relative importance of radiation dose, storage time, and temperature in radiation processing of spinach (Spinacia oleracea L.), was evaluated in terms of the postharvest quality through a model study using leaf disks. Physiological activity and chlorophyll and carotenoid contents were measured to represent the postharvest quality (in terms of external appearance) of spinach, a leafy green vegetable. At $22^{\circ}C$ and $30^{\circ}C$, the higher gamma-radiation dose caused a greater decrease in the physiological activity, depending on the storage time of 4 d. However, this decrease was not significant at $4^{\circ}C$ and $15^{\circ}C$. Total chlorophyll and carotenoid contents were substantially decreased by 3 kGy at $15^{\circ}C$, and dose-dependently by 0.5-3 kGy at $22^{\circ}C$. In contrast, the proportion of lutein in total carotenoid was significantly increased in the 2-3-kGy samples only at $22^{\circ}C$, while that of ${\beta}$-carotene was slightly decreased, indicating progression of leaf aging. These data suggest that the unfavorable effect of gamma irradiation on the postharvest quality of spinach could be avoided or controlled by the storage time or temperature rather than the radiation dose. The current study could be available to improve radiation processing of other leafy green vegetables.

• Korean Journal of Poultry Science
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• v.45 no.2
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• pp.73-79
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• 2018

The objective of this study was to calculate the unit price of an alternative feed ingredient for broiler chickens in consideration of the energy and nutritive contents in the feed ingredient by using a simple Excel worksheet. A corn-distiller's dried grains with solubles (corn-DDGS) was used as an alternative ingredient and corn and soybean meal as ingredients to be replaced. The net change of feed price was calculated based on the replacement values which were estimated in consideration of energy and nutrient concentration in feed ingredients used in the calculation, the price of feed ingredients and inclusion rate of the alternative ingredient. The nitrogen corrected apparent metabolizable energy(AMEn) and standardized ileal digestible AA including Lys, Met, Thr, and Trp, total Ca, and available P were employed as nutritive component to calculate the replacement values for individual feed ingredients. The equation for replacement was 1 ${\times}$ corn-DDGS + 0.0334 ${\times}$ soybean oil + 0.0182 ${\times}$ Limestone = 0.8893 ${\times}$ corn + 0.13 ${\times}$ soybean meal + 0.0004 ${\times}$ Lys + 0.0022 ${\times}$ Met + 0.0005 ${\times}$ Trp + 0.0028 ${\times}$ Thr + 0.0264 ${\times}$ dicalcium phosphate. The replacement price of corn-DDGS was calculated to be 270 won/kg when the inclusion rate was 15% and the energy and nutrient contents were considered in the calculation. In conclusion, the Excel-based ingredient price calculator may be useful to determine the economic value when an alternative feed ingredient is used in diets fed to broiler chickens.

• Journal of Nutrition and Health
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• v.40 no.sup
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• pp.3-8
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• 2007

Sugars are a ubiquitous component of our food supply and are consumed as a naturally occurring component of many foods and as additions to foods during processing, preparation, or at the table. Most fruits and dairy products are high in sugars and thus naturally occurring sugars are consumed as part of a healthy diet. Some countries developed recommended daily intake figures(daily values : DVs or guideline daily amounts: GDA) for nutrients, and some countries, but not most have developed DV/GDA for total sugars. Dietary Reference Intakes for Koreans established by the Korean Nutrition Society in 2005, did not include the reference values for total sugar or added sugar. The committee on Dietary Reference Intakes for sugar was constituted in 2006 and discussed whether to special added sugars or total sugar. Although added sugars are not chemically or physiologically different from naturally occurring sugars, many foods and beverages that are major sources of added sugars have lower micronutrient densities compared with foods and beverages that are major sources of naturally occuring sugars. But it was so hard to calculate a dietary intake of added sugar for Korean people, because there was insufficient information about contents of added sugar during processing or preparation of Korean food. Currently Korean or US food labels contain information on total sugars per serving but do not distinguish between sugars naturally present in food and added sugars. Therefore the committee decided to set the reference value for total sugar for Koreans. According to the recommended diet pattern for Koreans suggested by the Korean Nutrition Society, estimated sugar intake from the sugar containing food based on 2,000 kilocalories is 67 g or 13% of total energy. Based on the data available on risk of obesity, hypertension, hyperlipidemia, insulin resistance, and metabolic syndrome from the analysis of Korean NHANES, it was insufficient evidence to set a UL for total sugar, but tended to increase serum LDL cholesterol and obesity at over 20-25% of energy from total sugar when consumed with high carbohydrates. Therefore the committee on Dietary Reference Intakes for sugar set the Acceptable Macronutrient Distribution Range for total sugar as 10-20% of total energy intake.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.115-136
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• 2014

In this study, an extended Kantorovich method, employing multi-term displacement functions, is applied to analyze the vibration problem of symmetrically laminated plates with arbitrary boundary conditions. The vibration behaviors of laminated plates are determined based on the variational principle of total energy minimization and the iterative Kantorovich method. The out-of-plane displacement is represented in the form of a series of a sum of products of functions in x and y directions. With a known function in the x or y directions, the formulation for the variation of total potential energy is transformed to a set of governing equations and a set of boundary conditions. The equations and boundary conditions are then numerically solved for the natural frequency and vibration mode shape. The solutions are verified with available solutions from the literature and solutions from the Ritz and finite element analysis. In most cases, the natural frequencies compare very well with the reference solutions. The vibration mode shapes are also very well modeled using the multi-term assumed displacement function in the terms of a power series. With the method used in this study, it is possible to solve the angle-ply plate problem, where the Kantorovich method with single-term displacement function is ineffective.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.2
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• pp.51-66
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• 1984

The cost percentage of engine part in the total building cost of a ship is about 30-40% and the main engine occupies about 50% of the engine part cost. For certain ships the fuel bill can be as high as about 60-70% of the total operating cost after two oil shocks and its amount for one year is nearly equivalent to her main engine price. This fact has further increased the pressure on the engine builders to develop engines of higher efficiency and better possibilities to burn further deteriorated fuel qualities. But the energy-saving plants are ordinarily more expensive and their available amount of exhaust gas energy is less and therefore, they are not always profitable and optimum systems. This paper is prepared to decide the most economical and efficient engine systems by presenting reasonable selecting and economical evaluation methods of the main engine, which is the largest single unit and the most expensive, and its auxiliaries. In order to demonstrate the application of investigated methods in a practical case, a 46, 000 DWT class bulk carrier is selected as a model ship and her main engine and its auxiliaries are selected and evaluated. The result shows that the optimum determined has one year three months POP, 0.903 IRR at a year, 4, 116, 000 dollars PW in 15 years (for 5% escalation rate of fuel cost) and 9.522 BCR for same condition, when the engine plant of a same existing ship is taken as the basis.

• Clean Technology
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• v.17 no.4
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• pp.406-411
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• 2011

A detailed database of waste heat is built to propose energy exchange networks to recover waste energy in Pohang Steel Industrial Complex. A visualized technique is used to figure out the status of waste heat energy and to suggest potential energy exchange networks. Several energy networks are proposed in terms of temperature level, the amount of available energy, distance, and construction cost. A simple economical assessment is applied to the energy exchange networks which have higher economic potential. Their average payback period is estimated to be 2.8 years. The total amount of energy saving by constructing the proposed energy exchange networks is 4,778 TOE per year. It corresponds to 11,160 ton $CO_2$ reduction with the assumption that the recycled waste energy replaces the use of LNG in energy-demanding companies.