• 한국기계가공학회지
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• 제11권1호
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• pp.39-45
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• 2012

Currently, the aircraft industry, aircraft parts as well as airframe have been developed in producing, the aircraft parts and fuselages have been produced the product by cutting rather than forging and casting because of the residual stress and stress concentration. In this study, the aircraft is being used in many parts of aluminium alloy 2024 in wire-cut E.D.M. The selected experimental parameters are peak current, no-load voltage, off time and feed rate. It is found that cutting mountain part on surface roughness of the curve 0.3mm than 0.25mm diameter wire electrode is stable in many uniform distribution.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.14-18
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• 1996

From the experimental study of Wire-Cut EDM of die-material(SKD-11), machining characteristics such as machining rate, surface roughness and hardness have been observed and evaluated under the conditions varing pulse on time, pulse off time, peak voltage after fixing other conditions. It was found that various operating conditions have significant influences on machining rate, surface roughness. Hardness of workpiece was unaffected by operating conditions.

• 한국정밀공학회지
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• 제13권1호
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• pp.22-28
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• 1996

From the experimental study of Wire-Cut Electric Discharge Machining of STD-11 alloy steel and P-20 tungsten carbide, the characteristics such as hand drum form and discharge gap have been observed and evaluated for various conditions. Hand drum form can be improved when gap have been observed and evaluated for various conditions. Hand drum form can be improved when gap voltage and spark cycle become smaller, thickness become thinner, wire tension become larger and the no of cutting increases. When 60mm thickness tungsten carbide is cut in normal condition, hand drum form becomes larger due to the low conductivity machining allowance become slightly larger when peak discharge current and gap voltage become larger, or wire tension becomes smaller. Under the same condition, machining allowance of tungsten carbide is larger than alloyed steel by 1/100mm.

• 한국공작기계학회논문집
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• 제17권5호
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• pp.101-106
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• 2008

In the wire cut electrical discharge machining, the optimal machining parameters setting satisfying the requirements of both high efficiency and good quality is very difficult because its process involves a series of complex physical phenomena and the machining parameters are numerous over diverse range. In this paper, the experimental investigation has been performed to find out the influence of the machining parameters on the machining performance such as cutting speed and surface roughness. The selected experimental parameters are no load voltage, discharge peak current and pulse-off time. The experimental results give the guideline for selecting suitable machining parameters.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1157-1166
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• 2021

In this study, a numerical sensitivity analysis was performed to determine the fire suppression time for a large number of water mist nozzles in a large fire compartment. Fire simulations were performed using FDS (Fire dynamics simulator) 6.5.2 under the same condition as the test scenario 5 of the International Maritime Organization (IMO) 1165 test protocol. The sensitivities of input parameters including cell size, extinguishing coefficient (EC), droplets per second (DPS), and peak heat release rate (HRR) of fuel were investigated in terms of the normalized HRR and temperature distribution in the compartment. A new method of determining the fire suppression time using FDS simulation was developed, based on the concept of the cut-off time by cut-off value (COV) of the heat release rate per unit volume (HRRPUV) and the cooling time by the HRR cooling time criteria value (CTCV). In addition, a method was developed to determine the average EC value for the simulation input, using the cooling time and cut-off time.

• Journal of Yeungnam Medical Science
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• 제30권2호
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• pp.90-94
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• 2013

Background: This study was conducted to examine if basal luteinizing hormone (LH) levels could be useful for screening central precocious puberty (CPP) in girls. Methods: A total of 90 girls under the age of 8 years were included in this study. They underwent the gonadotropin-releasing hormone (GnRH) stimulation test at Good Gang-An Hospital from March 2008 to December 2012 for evaluation of premature sexual development. Patients were classified into two groups: the pubertal response group of patients who had 5 IU/L peak LH levels in the GnRH stimulation test, and the prepubertal response group of patients who had LH levels <5 IU/L. Chronological and bone ages, height, weight, body mass index, gonadotropin response to GnRH stimulation, and basal levels of LH, follicle-stimulating hormone, and estradiol were studied in both groups. The relationship between basal LH and peak-stimulated LH was evaluated using Spearman's correlation. To determine the optimal cut-off values of basal LH levels for differentiating between two groups, the receiver operating characteristic (ROC) curves were analyzed. Results: When the correlation between basal LH levels and peak LH after GnRH stimulation was analyzed in all subjects (N=90), basal LH levels had a statistically significant positive correlation with peak stimulated LH levels (rs=0.493, p<0.001). The cut-off level of optimal basal LH was 0.1 IU/L, according to the ROC curves. Its sensitivity was 73.3%, and its specificity was 77.8%. Conclusion: The study results showed that serum basal LH levels are useful for screening CPP in girls.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.20-27
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• 2014

The power consumption pattern of high-speed railway has rarely during night time. But, during service time, the power is consumed irregularly related to train operation. Especially certain unusual about 1-2 days of service time interval to indicate the power consumption is rapidly growing phenomenon, which causes the capacity of the power contract is the annual electricity bill to rise rapidly as the cause. Normally, amount of peak power consumption bill rate at railway substation is over 20% of total electrical bill. Therefore, high-speed railway substation is expected to be considerably larger savings by reducing the peak power of the default charge(demand power).

• 설비공학논문집
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• 제24권10호
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• pp.733-738
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• 2012

It is important issue to reduce the electric energy to save the operating cost of HVAC system. Even if electrical energy is the clean energy, it is difficult and takes high cost for storage of electricity. These cause the high peak load of electric energy for HVAC in summer season. In korea, government impose the electric charge with several grade for the purpose of cut-off the peak load of electricity. Government has a policy to support to design and install the heat/ice storage system using midnight electricity. In this study, analysis of cooling load and operating characteristics for ice storage system are performed. And, also economical efficiency is compared between ordinary charge system of electricity and midnight rate charge of electricity. The systematic and economical supports are needed for expansion of usage of energy saving equipments.

• Journal of Animal Science and Technology
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• 제62권4호
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• pp.587-594
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• 2020

In this study, we examined the effects of various hydrocolloid (alginate, carrageenan, and konjac) treatments on the quality characteristics of cold-cut duck meat jelly. Seven different types of cold-cut duck meat jelly were prepared: control, without hydrocolloids; T1, 0.5% alginate; T2, 0.5% carrageenan; T3, 0.5% konjac; T4, 0.25% alginate + 0.25% carrageenan; T5, 0.25% carrageen + 0.25% konjac; and T6, 0.25% alginate + 0.25% konjac. The pH and moisture content of the cold-cut duck meat jelly with hydrocolloids was higher (p < 0.05) than that of the control. The highest lightness value was recorded for T4 and T6 (p < 0.05), and the hardness was lower (p < 0.05) in the meat jelly with hydrocolloids than in the control, except for T2 and T5. The springiness of the meat jelly was the highest (p < 0.05) in T1 and T4. The onset, peak, and end temperatures were the lowest (p < 0.05) in the control. The highest appearance score of the meat jelly was observed in T6, and its overall acceptability was higher (p < 0.05) than that of the control, indicating that, of all the treatments, 0.25% alginate + 0.25% konjac yielded the most desirable results. Thus, the combined use of duck skin and gelatin with alginate and konjac is potentially applicable for the development of new cold-cut duck meat products.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.502-514
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• 1998

The purpose of this study is to observe the corrosion characteristcs of four dental amalgams(CAULK FINE CUT, CAULK SPHERICAL, DISPERSALLOY, TYTIN) and to determine a function of chloride concentration through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylinderical metal mold, and condensed by hydrolic pressure. Each specimen was removed from the metal mold. 24 hours after condensation, specimens were polished with the emery paper and stored at room temperature for 6 months. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgam m KCl and KCl-NaCl solution, which had chlonde concentration of 0.4 g/l, 0.8 g/l, 1.2 gil, and 1.6 gil at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 1 hour, the potential scan was begun. The potential scan range was - 1500mV ~+800mV(vs. S.C.E.) in the working electrode and the scan rate was 50mV/sec. The results were as follows, 1. The corrosion potential. the potential of anodic current peak, and transpassive potential in the solution of high chloride concentration shifted to more cathodic direction than those in the solution of low concentration, and the current density in the solution of high chloride concentration was higher than that in the solution of low concentration. 2. The corrosion potential, the potential of anodic current peak, and transpassive potential for CAULK FINE CUT amalgam were the most cathodic among the others, and the current density were the highest among the others. 3. In the solution of low chloride concentration, the corrosion potential, the potential of anodic current peak, and transpassive potential for DISPERSALLOY were the most anodic among the others, however in the solution of high chloride concentration, those for TYTIN were the most anodic among the others. 4. The anodic polarization curve for CAULK SPHERICAL was similar to that for high copper amalgams.