• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.85-92
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• 2018

Reductions of the electricity charge are achieved by demand management of the load. The demand management method of the load using ESS involves peak shifting, which shifts from a high demand time to low demand time. By shifting the load, the peak load can be lowered and the energy charge can be saved. Electricity charges consist of the energy charge and the basic charge per contracted capacity. The energy charge and peak load are minimized by Linear Programming (LP) and Quadratic Programming (QP), respectively. On the other hand, each optimization method has its advantages and disadvantages. First, the LP cannot separate the efficiency of the ESS. To solve these problems, the charge and discharge efficiency of the ESS was separated by Mixed Integer Linear Programming (MILP). Nevertheless, both methods have the disadvantages that they must assume the reduction ratio of peak load. Therefore, QP was used to solve this problem. The next step was to optimize the formula combination of QP and LP to minimize the electricity charge. On the other hand, these two methods have disadvantages in that the charge and discharge efficiency of the ESS cannot be separated. This paper proposes an optimization method according to the situation by analyzing quantitatively the advantages and disadvantages of each optimization method.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.153-157
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• 2016

Background: In radiation therapy, estimation of surface doses is clinically important. This study aimed to obtain an analytical relationship to determine the skin surface dose, kerma and the depth of maximum dose, with energies of 6 and 18 megavoltage (MV). Materials and Methods: To obtain the dose on the surface of skin, using the relationship between dose and kerma and solving differential equations governing the two quantities, a general relationship of dose changes relative to the depth was obtained. By dosimetry all the standard square fields of $5cm{\times}5cm$ to $40cm{\times}40cm$, an equation similar to response to differential equations of the dose and kerma were fitted on the measurements for any field size and energy. Applying two conditions: a) equality of the area under dose distribution and kerma changes in versus depth in 6 and 18 MV, b) equality of the kerma and dose at $x=d_{max}$ and using these results, coefficients of the obtained analytical relationship were determined. By putting the depth of zero in the relation, amount of PDD and kerma on the surface of the skin, could be obtained. Results: Using the MATLAB software, an exponential binomial function with R-Square >0.9953 was determined for any field size and depth in two energy modes 6 and 18MV, the surface PDD and kerma was obtained and both of them increase due to the increase of the field, but they reduce due to increased energy and from the obtained relation, depth of maximum dose can be determined. Conclusions: Using this analytical formula, one can find the skin surface dose, kerma and thickness of the buildup region.

• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.168-173
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• 2021

In this study, we measured total flavonoids after extracting the total flavonoids from lemongrass which is known to have a high content of antioxidant ingredients when using microwave energy. Also, optimal extraction conditions of active ingredients using central composite design-response surface methodology (CCD-RSM) were presented. Both ultrapure water and alcohol were used as extraction solvents and the volume ratio of ethanol/ultrapure water, microwave irradiation time, and microwave irradiation power were set as independence variables. And the extraction yield and total flavonoids were measured. The optimal extraction conditions using CCD-RSM were the volume ratio of ethanol/ultrapure water = 56.3 vol.%, the microwave irradiation time = 6.1 min, and the microwave irradiation power = 574.6 W. We could also obtain expected results of yield = 17.2 wt.% and total flavonoids = 44.7 ㎍ QE/mL dw under the optimum conditions. The comprehensive satisfaction degree of this formula was 0.8562. The P-value was calculated for the yield of 0.037 and the total flavonoids content of 0.002. The average error from actual experiments established for the verification of conclusions was lower than 2.5%. Therefore, a high favorable level could be obtained when the CCD-RSM was applied to the optimization of extraction process.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.719-725
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• 2022

This study aimed to measure, quantitatively evaluate, and set the criteria for the minimum lead(Pb) shield thickness per level of clinically applied electron beam energy. The lead shield thickness per electron beam energy was measured using the primary field 95% reduction based on the open field at the depth of maximum dose (d_max) and depth from the surface as the reference depth of tissue dose(10 mm). The measured values were 1.906 mmPb and 1.992 mmPb at the d_max and 10 mm, respectively, regarding the lead shield thickness for 6 MeV electron beam; 2.746 mmPb and 3.743 mmPb for 9 MeV electron beam, 3.718 mmPb and 6.093 mmPb for 12 MeV electron beam, 7.300 mmPb and 15.270 mmPb for 16 MeV electron beam, and 16.825 mmPb and 25.090 mmPb for 20 MeV electron beam. Consequently, a thicker lead shield was required if the measurement was at 10 mm. The required lead shield thickness was also higher than that of the theoretical formula for electron beams of ≥ 16 MeV.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.519-530
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• 2023

Moye's analytical solution was examined as a method for constant-head tests under steady-state conditions, and results were compared with transient-state analyses in in situ hydraulic tests. The sensitivity of hydraulic conductivities calculated using Moye's method increased with the length of the test section, which should be as large as possible under test conditions. Particularly in low-permeability media with less than 10^-8 m/sec of hydraulic conductivity, hydraulic conductivity is lower than that under transient-state conditions and can be recalculated by adjusting the boundary between radial and spherical flow assumed in Moye's equation. Constant-head tests performed in the research borehole at the KAERI Underground Research Tunnel (KURT) indicated that transmissivities derived from the constant-head withdrawal test under transient-state conditions in low-permeability media were higher than those derived from steady-state tests, likely because the groundwater flow boundary was smaller than the "half of the test-section length"assumed by Moye's equation. When interpreting constant-head test results for crystalline rock, the hydrogeological properties of the medium may be better understood by considering assumed conditions accompanying analysis of the steady-state condition and comparing them with results for the transient-state analysis, rather than simply assuming properties based on steady-state analyses.

• Journal of Nutrition and Health
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• v.9 no.1
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• pp.84-91
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• 1976

Chemical determination were made to analyze the concentration of nutrients including proximate composition, vitamins, minerals, amino acids and fatty acids in three kinds of locally produced infantile formula milk(DFM) and one fermented milk(FM). An attempt was also made to compare the analytical values of nutrients against guaranteed values. The results obtained are summarized as follows; 1. The analyzed value of protein and fat content in DFM-A.B.C was slightly lower than that of guaranteed values and a reverse trend was observed in the case of total carbohydrate. There were no differences in proximate composition among the three kinds of DFM. It was found that the FM contained less protein and fat than the fresh milk, but it seemed that a considerable amount of sugar was added to FM. 2. The analyzed values of vitamin $A(2{\sim}3\;times)$ and $E(4{\sim}6\;times)$ contents in DFMS were higher than those of the guaranteed values except niacin. There were a little differences in vitamin contents among DFMS analyzed. 3. In the case of minerals, the analyzed values were similar to the guaranteed values except the calcium concentration that analyzed value was much higher than guaranted value. When the DFMS were diluted to 15% by adding water to compare with the human and fresh cow milk, it was found that the diluted DFMS resembled the human milk rather than cow milk in the content of energy, carbohydrates, protein and ash. The higher contents of iron and most vitamins in the diluted DFMS than the human milk or cow milk would indicate that they were fortificated with these nutrients. When these diluted DFMS were compared with the Korean R.D.A. for infant, it was clear that they could supply sufficient amount of the nutrients required by R.D.A. except the niacin which failed to reach the recommended level. The fact that iron content of DFM-C was not sufficient while vitamin A supply was excessive by 6 fold would indicate that further studies for the improvement may be necessary. 4. There was a little difference among DFMS in amino acid composition. The similarity of the essential amino acids composition between DFMS and cow milk indicated that there was no modification of the essential amino acids. However, present data showed that the amino acid compositon of FM was similar to that of the cow milk. 5. There was no difference among DFMS in the degree of saturation of fatty acids. The similar or higher levels of essential fatty acids contents of DFMS as compared with human milk revealed that essential fatty acids were added to DFMS during the course of process. From the experimental results described above, it may be concluded that the nutritive effects of three kinds of locally produced DFMS were much alike. It was also found that macro and micro nutrient composition except amino acid composition of locally produced dried formula milk was very much similar to that of the human milk. Moreover, fortification of iron and vitamins resulted in improving their nutritive values as the single form of infantile food, but it seemed that more consideration should be given on the fortification of some nutrients.

• Composites Research
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• v.17 no.1
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• pp.29-37
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• 2004

Honeycomb sandwich composite(HSC) structures have been widely used in aircraft and military industry owing to their light weight and high stiffness. Mechanical properties of honeycomb core materials are needed for accurate analysis of the sandwich composites. In this study. theoretical formula for effective elastic modulus and Poisson's ratio of honeycomb core materials was established using an energy method considering the bending, axial and shear deformations of honeycomb core walls. Finite-element analysis results obtained by using commercial FEA code, ABAQUS 6.3 were comparable to the theoretical ones. In addition, we performed tensile test of HSC plates and analyzed deformation behaviors and interlaminar stresses through its FEA simulation. An increased shear stress along the interface between surface and honeycomb core layers was shown to be the main reason for interfacial delamination in HSC plate under tensile loading.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.393-400
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• 2009

The present study developed a new technique with no physical object on the flow stream but enabling the air flow measurement and easily incorporated with the devices for cardiopulmonary resuscitation(CPR) procedure. A turbulence chamber was formed in the middle of the respiratory tube by locally enlarging the cross-sectional area where the flow related turbulence was generated inducing energy loss which was in turn converted into pressure difference. The turbulence chamber was simply an empty enlarged air space, thus no physical object existed on the flow stream, but still the flow rate could be evaluated. Computer simulation demonstrated stable turbulence formation big enough to measure. Experiment was followed on the proto-type transducer, the results of which were within ${\pm}5%$ error compared to the simulation data. Both inspiratory and expiratory flows were obtained with symmetric measurement characteristics. Quadratic curve fitting provided excellent calibration formula with a correlation coefficient>0.999(P<0.0001) and the mean relative error<1%. The present results can be usefully applied to accurately monitor the air flow rate during CPR.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.34-39
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• 2010

Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity through the experiment, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the radius of flame curvature. In the present research, a relation of the flame propagation velocity is proposed with the radius of flame curvature for the flame stabilization mechanism. As a result, we have shown that the height of lifted flame is determined with the nozzle diameter and exit velocity of fuel and presented that the radius of flame curvature is proportion to the nozzle exit velocity of fuel and height of lifted flame. Therefore, the importance of the radius of flame curvature has to be recognized. To discribe the flame stabilization mechanism, Bilger's formula has to be modified with flame curvature effect.

• Nutrition Research and Practice
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• v.9 no.1
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• pp.57-62
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• 2015

BACKGROUND/OBJECTIVES: The prevalence of atopic dermatitis in infants is increasing worldwide. However, the nutrient intake status of infants with atopic dermatitis has not been studied properly. This study was conducted to compare the nutrient intake status of infants in the weaning period with atopic dermatitis by feeding type. MATERIALS/METHODS: Feeding types, nutrient intake status and growth status of 98 infants with atopic dermatitis from age 6 to 12 months were investigated. Feeding types were surveyed using questionnaires, and daily intakes were recorded by mothers using the 24-hour recall method. Growth and iron status were also measured. RESULTS: The result showed that breastfed infants consumed less energy and 13 nutrients compared to formula-fed or mixed-fed infants (P < 0.001). The breastfed group showed a significantly lower intake rate to the Dietary Reference Intakes for Koreans than the other two groups (P < 0.001). In addition, they consumed less than 75% of the recommended intakes in all nutrients, except for protein and vitamin A, and in particular, iron intake was very low, showing just 18.7% of the recommended intake. There was no significant difference in growth by feeding type, but breastfed infants showed a significantly higher rate of iron deficiency anemia (P < 0.001). CONCLUSIONS: Continuous management programs should be prepared for breastfed infants with atopic dermatitis, who are in a period when rapid growth takes place and proper nutrient intake is essential.