• 전기화학회지
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• 제17권1호
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• pp.26-29
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• 2014

The corrosion behavior of stainless steel 304 (SS 304), titanium, nickel and aluminium is studied by immersion and anodic polarization tests in non-aqueous electrolytes. Tetraethyl ammonium tetrafluoroborate is used as a supporting electrolyte in the three kinds of solvents. The immersion test shows that chemical corrosion rate in propylene carbonate-based electrolyte is lower than those in acetonitrile- or ${\gamma}$-butyrolactone-based electrolytes. Surface analyses do not reveal any corrosion product formed after the immersion test. In the anodic polarization tests, a higher concentration of supporting electrolyte gives a higher current density. In addition, a higher temperature increases the current density in the active region and reduces the potential range in the passive region. SS 304 shows the highest corrosion potential while Al shows the lowest corrosion potential and the highest current density in all studied conditions. Based on the conducted corrosion tests, the corrosion resistance of metal substrates in the organic solvents can be sorted in descending order as follows: SS 304 - Ti - Ni - Al.

• Journal of Nutrition and Health
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• 제49권5호
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• pp.395-399
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• 2016

Purpose: Gongju is a famous area for chestnuts, which contain various nutrients and phytochemicals. This study aimed to develop gochujang items using Gongju chestnuts and analyze nutritional properties for the best item by sensory evaluation in order to increase marketability of chestnut processed foods. Methods: Gochujang was prepared, and nutrient contents of gochujang were analyzed according to the methods of the food fair by Korea Food Research Institute. Three kinds of gochujang, including general (control)-, dried chestnut powder-, and chestnut syrup- were prepared. Sensory evaluation was performed on three kinds of gochujang by 45 adults, including males and females (20's~60's years of age). Results: Chestnut syrup-gochujang was evaluated as significantly higher than general- or dried chestnut powder-gochujang by sensory evaluation. Thus, nutrition facts were produced for chestnut syrup gochujang. Nutrient contents per 100 g of chestnut syrup gochujang and traditional gochujang in the literature were similar in terms of total carbohydrates and fat, whereas protein content was higher and sodium content was lower in chestnut syrup gochujang than in traditional gochujang in the literature. Conclusions: The results imply that chestnut syrup gochujang has nutritional benefits such as higher content of protein and lower content of sodium than traditional gochujang in the literature, in addition with its good taste. Therefore, chestnut syrup gochujang may have high usage potential. There is a need to improve the quality and storage of chestnut syrup gochujang through future study.

• 상하수도학회지
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• 제33권1호
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• pp.43-53
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• 2019

In the Geumho River, 4-nitrophenol has been detected, thus it is necessary to investigate the contamination sources in order to prevent the release of this compound. However, the research to estimate the potential source is regarded as complicated research. In this study, the distributions of 4-nitrophenol were simulated and the contribution of the potential sources was estimated using a numerical model(HydroGeoSphere; HGS) and the measuring data of 4-nitrophenol from 2013 to 2017. The altitude data, the land cover data, the flow rates of the tributaries and wastewater treatment plants, and the decay rate of 4-nitrophenol was used as the input data. The results of this research showed that the contribution rates of potential contamination sources in the upstream area were higher than that of the downstream area. Most of the upstream area is the agricultural area, it seemed that 4-nitrophenol was originated from the pesticides. In order to achieve more specific location of sources, an intensive investigation in the upstream is required.

• Structural Engineering and Mechanics
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• 제78권1호
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• pp.31-39
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• 2021

To investigate numerically the effect of all parameters on the outcome of an aircraft impact into robust engineering structures like nuclear power plant containments is a tedious task. In order to reduce the problem to a manageable size, we propose a single dimensionless parameter, the damage potential, to characterize the main features of the impact. The damage potential, which is the ratio of the initial kinetic energy of the aircraft to the work required to crush it, enables us to find the crucial parameter settings that need to be modelled numerically in detail. We show in this paper that the damage potential is indeed the most important parameter of the impact that determines the time-dependent reaction force when either finite element (FE) modelling or the Riera model is applied. We find that parameters that do not alter the damage potential, like elasticity of the target, are of secondary importance and if parameters are altered in a way that the damage potential remains the same then the course of the impact remains similar. We show, however, that the maximum value of the reaction force can be higher in case of elastic targets than in case of rigid targets due to the vibration of the target. The difference between the Riera and FE model results is also found to depend on the damage potential.

• Steel and Composite Structures
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• 제21권4호
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• pp.883-919
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• 2016

In this research, buckling analysis of an embedded laminated composite plate is investigated. The elastic medium is simulated with spring constant of Winkler medium and shear layer. With considering higher order shear deformation theory (Reddy), the total potential energy of structure is calculated. Using Principle of Virtual Work, the constitutive equations are obtained. The analytical solution is performed in order to obtain the buckling loads. A detailed parametric study is conducted to elucidate the influences of the layer numbers, orientation angle of layers, geometrical parameters, elastic medium and type of load on the buckling load of the system. Results depict that the highest buckling load is related to the structure with angle-ply orientation type and with increasing the angle up to 45 degrees, the buckling load increases.

• Structural Engineering and Mechanics
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• 제55권2호
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• pp.435-459
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• 2015

Parametric resonance of shear deformable composite skew plates subjected to non-uniform (parabolic) and linearly varying periodic edge loading is studied for different boundary conditions. The skew plate structural model is based on higher order shear deformation theory (HSDT), which accurately predicts the numerical results for thick skew plate. The total energy functional is derived for the skew plates from total potential energy and kinetic energy of the plate. The strain energy which is the part of total potential energy contains membrane energy, bending energy, additional bending energy due to additional change in curvature and shear energy due to shear deformation, respectively. The total energy functional is solved using Rayleigh-Ritz method in conjunction with boundary characteristics orthonormal polynomials (BCOPs) functions. The orthonormal polynomials are generated for unit square domain using Gram-Schmidt orthogonalization process. Bolotin method is followed to obtain the boundaries of parametric resonance region with higher order approximation. These boundaries are traced by the periodic solution of Mathieu-Hill equations with period T and 2T. Effect of various parameters like skew angle, span-to-thickness ratio, aspect ratio, boundary conditions, static load factor on parametric resonance of skew plate have been investigated. The investigation also includes influence of different types of linearly varying loading and parabolically varying bi-axial loading.

• International journal of advanced smart convergence
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• 제9권4호
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• pp.8-15
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• 2020

This study was conducted in order to determine the effect of intraoperative hemoglobin changes on intraoperative neuromonitoring (IONM). This was a retrospective study that included 339 participants who underwent cerebrovascular surgery. We compared anesthetic agents, intraoperative hemoglobin, hematocrit, blood transfusion, and blood loss. We examined motor evoked potential and sensory evoked potential to patients. There were significant differences in hemoglobin changes, bleeding levels, transfusion, anesthesia time, and postoperative mobility disorders. Moreover, compared with patients who received transfusions, those who did not receive transfusion had a lower average hemoglobin level, as well as a higher bleeding amount, and a need of higher anesthesia time and anesthetic dose. Also, we found vasospasm occurred while surgery can bring adverse results after operation. This study showed that an intraoperative decrease in hemoglobin levels affects the function of cerebral perfusion, which could result in abnormal nerve monitoring results. However, as this study could not find a relation of anesthetics to IONM, there is a need for further research regarding the association between anesthetics and hemoglobin changes and IONM.

• The Korean Journal of Ecology
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• 제9권4호
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• pp.201-208
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• 1986

The water status of the leaves of several evergreen plants was investigated in order to discuss the geopgraphical distribution of them. Relastionship between relative water content and water potential of the leaves showed linear decrease for evergreen conifers but exponential decrease for Korean box tree (Buxus microphylla var. koreana). On the basis of the leaf water potential, the water status of the conifers during wintering was distinctly divided into three periods; hardening, cold resistance and dehardening, but lacking in those periods for the Korean box tree, where the status continously decreased. In the cold resistance the leaf water potentials were -23 bar for both spruce (Picea jezoensis) and yew (Taxus cuspidata). From these results and threshold temperature at beginning of hardening, distribution of the conifers was explained that in order of the red pine, the Korean white pine, the yew and the spruce the distribution could be extended at higher altitudes and in more northward areas, whereas the distribution of the Korean box tree was restricted to the lowland of temperate zone.

• 한국표면공학회지
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• 제31권3호
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• pp.157-164
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• 1998

Effects of alloying elements on the pitting behavior of Ti-Al intermetalic compounds in the electrolytic soution containing Cl- were investigated through electrochemical tets and corrosion morphologies. Corrosion potential increased in the case of Cr addition to Ti-48%Al, whereas it decreased in the case of Si and B addition. The simultaneous addition of Cr and Si increased passive current density and decrosion corrosion potential. The passive current density of N addtion was higher than that of B addition in H2SO4 solution. With the addition of alloying elements, The pitting resistance decreased in order of TiAl>TiAlSi>TiAlN>TiAlB>TiAlCr and whin siumultaneous addition, it decreased in order of TiAlCrSi>TiAlCrBN>TiAlCrrN. The surface merohology after pitting test showed that the TiAl coataining Si had for fewer pits than that containing Cr and N simultaneously.

• 한국관개배수논문집
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• 제17권2호
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• pp.82-94
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• 2010

Recently, biomass application for energy is getting more interests from many countries since biomass is widely available over the nation wide, whereas fossil fuels are produced in several limited regions. Recognizing the importance, government is promoting renewable energy use in Korea. The locational characteristics of the existing biomass potential directly can be used to decide scale of power plant for local agricultural facility. Although there are a few studies on feasible biomass potential in local areas, it is expected that both government and commercial sectors recognize the potential of biomass energy and the importance of reducing greenhouse gases. When planning biomass energy systems, biomass price is determined by the costs of collection, transportation, chipping, drying if required. In this paper investigates the economic and spatial characteristic of biomass location by land use map. However typical area of each categories in local region is not correct to agricultural census data. Therefore we concerned about how to calculate feasible biomass potential which it can be describing total amount of plant scale, and to match both of data. Even though its spatial distribution, in rural area in Korea, to expand biomass energy programs in the area, government serve to find areas of higher biomass production with suitable locations for plants to convert to bio-energy in order to increase the usage of renewable energy.