• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1070-1074
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• 2014

According to IEEE 1662(2009), IPS is a power system where all prime movers produce electrical power that is shared among propulsion, mission, and ship service loads. Discriminating attributes of integrated power systems are flexibility of movers' arrangements, mechanical decoupling between prime movers and propulsors, an increased level of energy conversion and transmission redundancy, and flexibility of redistributing available electrical power for future electronic weapons. IPS could have various steps of power that can be produced at optimal load of movers. In this study, an evaluation method for optimal arrangement of movers was investigated when an IPS warship is projected. The two factors are utilized for the quantitative analysis which are the weight of system as the fighting power and the fuel consumption per year as the economic feasibility. And also the ways for arrangement of system were studied according to existence of small diesel generator. The evaluation method that decides the optimization level is based on the DEA(Data Envelopment Analysis)

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.345-350
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• 2017

The sintered density of uranium oxide pellets for pressurized water reactors is generally analyzed with pellet's samples completed with the sintering process. In this paper, the sintered density was analyzed by the newly developed method measuring the chromatography of ammonium diuranate, a precursor of uranium oxide, by a spectrophotometer (CM-5, Konica Minolta) before completing the sintering process. As a result of the sintered density analysis based on the brightness, color coordinate values (L, a, b) obtained from five ammonium diuranate samples by a spectrophotometer and the trend line of sintered density analyzed by a previous method, the sintered density with respect to the L value was observed with 0.9967 of the decision factor $R^2$. In case of a value, $R^2$ value was 0.9534 indicating lower reliability than that of the L value. However, b value with $R^2$ value of 0.4349 showed a very low correlation.

• International Journal of Highway Engineering
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• v.3 no.4 s.10
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• pp.127-136
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• 2001

To increase the structural integrity of concrete box culvert good compaction by the dynamic compaction roller with bi9 capacity is as effective as good backfill materials. It is needed for effective compaction that a compaction roller closes to concrete structure with high frequency. However structural distress of the culvert could be occur due to the excessive earth pressure by great dynamic compaction load. To investigate the characteristics of Induced stress by compaction, a box culvert was constructed with changing cushion materials and compaction methods. Two types of cushion material such as tire rubber chip and EPS(Expanded Polystyrene) were used as cushion panels and they are set on the culverts before backfill construction. Laboratory test result of cushion material says that the value of dynamic elastic modulus of rubber is lesser than that of EPS. On the other hand, material damping of rubber material is greater than that of EPS. In most case, dynamic compaction rollers with 10.5 ton weights were used and vibration frequency was applied 30Hz for the great compaction energy. This paper presents the main results on the characteristics of dynamic earth pressures during compaction. The amounts of induced dynamic pressures$(\Delta\sigma\;h)$ by compaction are affected with construction condition such as compaction frequency, depth of pressure cell, distance between roller and the wall of culvert and roller direction. Based on the measured values dynamic lateral pressure on the culverts, it could be said that orthogonal direction of roller to the length of culvert is more effective to compaction efficiency than parallel direction.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1729-1735
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• 2004

A total of 140 weaning pigs were used to determine the effects of digestive enzyme supplementation to corn-soybean meal diets on growth performance, physiological changes of small intestine, microorganisms and pH in the gastrointestinal tract. Two kinds of enzyme complex (A, B) were used in this experiment. Pigs were allotted in a completely random design (CRD) to five replicates with four pigs per pen. Diets and water were provided for ad libitum consumption. Treatments included 1) Control: without enzyme supplementation, 2) Enzyme A 0.05%, 3) Enzyme A 0.10%, 4) Enzyme A 0.15%, 5) Enzyme B 0.05%, 6) Enzyme B 0.10%, 7) Enzyme B 0.15% in the diets. A total of 24 crossbred barrows 25.78${\pm}$0.55 kg BW fitted with simple ileal T-cannulas were used to evaluate the effect the enzyme addition on the nutrient digstibility. Pigs were allotted 4 treatments (No enzyme, enzyme A 0.05%, enzyme A 0.1%, enzyme A 0.15%), 6 replicates according to a completely random design (CRD). Another digestibility trial was followed for enzyme complex B. Twenty pigs, average 31.92${\pm}$0.37 kg BW, fitted with simple ileal T-cannulas for digestibility trial. Neither enzyme A nor enzyme B affected on fecal or ileal digestibility of dry matter, gross energy, crude protein, crude fat and crude ash (p>0.05). The apparent fecal digestibilities of all the nutrients were higher in total feces collection method than in indirect method. At the end of feeding trial, 21 pigs were slaughtered for examining the morphological changes of small intestine and the concentration of microorganisms in the ileum and the colon. Growth performance, intestinal morphology and pH of ileum and colon were not affected by the either enzyme complex supplementation (p>0.05). These results suggested that enzyme complex A and enzyme complex B were of no benefit to early-weaned pigs when corn-soybean meal based diet was provided.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.760-767
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• 2020

Sustainable growth of hydroelectric power plants is expected in consideration of climate change and energy security. However, hydroelectric power plants always have a risk of water hammer damage, and safety assurance is very important. The water hammer phenomenon commonly occurs during operations such as rapid opening and closing of the valves and pump/turbine shutdown in pipe systems, which is more common in cases of emergency shutdown. In this study, a computational numerical model was developed using the MOC-FDM scheme to reflect the mechanism of water hammer occurrence. The proposed model was implemented in boundary conditions such as reservoir, pipeline, valve, and pump/turbine conditions and then applied to simulate hypothetical case studies. The analysis results of the model were verified using the analysis results at the main points of the pipe systems. The model produced reasonably good performance and was validated by comparison with the results of the SIMSEN package model. The model could be used as an efficient tool for the safety assessment of hydroelectric power plants based on accurate prediction of transient behavior in the operation of hydropower facilities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.528-535
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• 2020

Recently, the protection coordination method of DC systems has been presented because renewable energy and distributed resources are being installed and operated in distribution systems. On the other hand, it is difficult to detect ground faults because there is no significant difference compared to a steady-state current in ungrounded IT systems, such as DC load networks and urban railways. Therefore, this paper formulates the detection principle of IMD (Insulation Monitoring Device) to use it as a protection coordination device in a DC system. Based on the signal injection method of IMD, which is analyzed by a wavelet transform, this paper presents an algorithm of detecting ground faults in a DC system in a fast and accurate manner. In addition, this paper modeled an IMD and an ungrounded DC system using the PSCAD/EMTDC S/W and performed numerical analysis of a wavelet transform with the Matlab S/W. The simulation results of a ground fault case in an ungrounded DC system showed that the proposed algorithm and modeling are useful and practical tools for detecting a ground fault in a DC system.

• Korean Journal of Community Nutrition
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• v.11 no.3
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• pp.307-316
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• 2006

This study was conducted to investigate the relationships among body composition, dietary intake, and clinical blood indices in college students by body mass index (BMI). Their body compositions were determined by means of BIA (Bioelectrical Impedance Analysis) method. Their dietary intake was determined using a 3-day record method and their hematological indices were determined by semi-automated microcell counter (Sysmex F-520). Their serum lipid levels were measured using biochemical analyzer (Spotchem). Subjects were classified as underweight, normal or over-weight groups according to their BMI. The subjects were 69 healthy college students aged 20 to 26 years. The average age, height, weight, and BMI was 21.3 years, 162.6 cm, 54.4 kg, and $20.6cm/m^2$, respectively. Their average consumption of energy was 1693 kcal, 84.7% of RDA and their mean ratio of carbohydrate: protein: fat were 54.5 : 16.4 : 29.0. There was no significant difference in nutrient intake among the groups except ${\beta}$-carotene and vitamin C. The ${\beta}$-carotene intake was significantly higher in the underweight group. Vitamin C intake was significantly higher in the overweight group. The mean intakes of Ca, Fe, Zn and folate of subjects were 74.8% to 83.2% of RDA. Especially, intakes of Ca, Fe, Zn and folate were lower in the abnormal weight groups. The overall mean values of the hematological indices in female college students were within the normal range and there was no significant difference among the groups. However, anemic subjects with hemoglobin (< 12 g/dl) and hematocrit (< 36 g/dl) accounted for about 11% of the subjects. The everall mean values of the serum lipid levels were within the normal range and there was no significant difference among the groups. But serum HDL-cholesterol level of the overweight group was lower than that of the other groups. LDL-/HDL-cholesterol ratio and AI index were significantly higher in the overweight group compared to the other groups. Based upon this study, it is necessary for college women to be educated regarding consuming more Ca, Fe, Zn, folate and less fat and cholesterol in order to have better health promotion.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.131-137
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• 2011

A simple and rapid electrochemical method for the quantitative analysis of $Mn^{2+}$ ion is demonstrated with a view to examine the $Mn^{2+}$ dissolution behavior of $LiMn_2O_4$. The method described herein is based on the oxidation reaction of $Mn^{2+}$ to $Mn^{4+}(MnO_2)$ in aqueous buffer solution. Under the optimum condition (pH 8.9 0.04 M $NH_3-NH_4Cl$ buffer solution and glassy carbon working electrode), the linear range of $5{\mu}M-100{\mu}M$ (0.275-5.5 ppm) [$Mn^{2+}$] is obtained for the Linear sweep voltammetry(LSV) and $0.2{\mu}M-10{\mu}M$ (0.011-0.55 ppm) [$Mn^{2+}$] for the differential pulse voltammetry (DPV), respectively. It is also noted that the oxidation reaction of $Mn^{2+}$ ion is reduced with increasing amount of the electrolyte ($LiPF_6$, EC, EMC) added to the measuring solution, which is found to be mainly due to $LiPF_6$ and EC rather than EMC.

• Journal of radiological science and technology
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• v.34 no.1
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• pp.43-50
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• 2011

In this study we modeled the varian 2100C/D linear accelerator head and multi-leaf collimator by simulation with the GEANT4 Monte Carlo toolkit. Then central axis percentage depth dose profiles and lateral dose profiles within homogeneous water phantom($50{\times}50{\times}50\;cm^3$) were evaluated with 6 MV photon beam. The simulations were performed in two stages. In the first stage, photon energy spectrum at the target were computed were computed. Then spectra data was directly irradiated in the water phantom using sampling techniques. The simulation data were compared with experimental data to evaluate the accuracy of the model. Results showed that two data were matched within 2% error boundary. The proposed method will be applied for simulation of dose calculation and dose distribution study.

• Journal of Technology Innovation
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• v.20 no.2
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• pp.161-187
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• 2012

Recently, environmentally friendly technology are becoming important due to reconsideration about climate change and environmental pollution. In addition, as well as technical skills and social interaction through an analysis of the nonlinear transition management and policy implementation are emerging. This study of the development of photovoltaic industry in Korea 10 years analyze with strategic niche management (SNM) based on the theoretical and multi-layered perspective (MLP) is used as the analytical framework. Choose the gerverment-support project for niche technology, through a process of quantifying and alnalyze the phase transition to Regime with the numerical method and policy vision, learning effects, and network that key elements of SNM, MLP. Through the analysis of the photovoltaic industry technology-commercialization phase was investigated. This conventional overall and step-by-step model for technical management is proposed to replace exiting linear and narrow method and through the case study its validity was confirmed.