• Physical Therapy Korea
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• v.12 no.2
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• pp.90-97
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• 2005

By measuring changes in blood lactate and plasma enzyme (CPK, GOT, GPT) with electrical stimulation applied at two duty cycles, this study is intended to look into which type of duty cycle may have more effects on blood lactate and plasma enzyme constituents through animal experiment so as to determine any duty cycle appropriate for electrical treatment. In this study, electrical stimulation was applied to total 20 Korean house rabbits (weight: 3~3.5 kg) by means of an electrical therapeutic apparatus called TS6000 (made in Netherlands) at duty cycle of 50% and 20% respectively for 30 minutes. Here, 5 cc of blood was collected from their carotid artery before stimulation and in 30 minutes after stimulation respectively to carry out biochemical experiment and analysis. As determined through the above experiment, blood lactate rate was increased to 333.07% at 50% duty cycle after experiment and 185.71% at 20% duty cycle after experiment respectively. In both cases, blood lactate rate was significantly increased to higher level after electrical stimulation than before. Moreover, the rate of change in the average of blood lactate rate at both duty cycles also showed significant differences. CPK rate was boosted to 301.82% at 50% duty cycle after experiment and 321.35% at 20% duty cycle after experiment respectively. In both cases, CPK rate was remarkably boosted to higher level after stimulation than before (p<.05). However, there was not any significant difference in the rate of change in average CPK at both duty cycles (p<.05). GOT rate was significantly boosted up to 38.97% at 50% duty cycle after experiment (p<.05), while it was slightly increased to 1.68% at 20% duty cycle after experiment without any significant difference. Rather, GPT rate dropped slightly at both duty cycles after experiment, but there was not any significant difference. Although blood lactate and GOT were relatively less generated at 20% duty cycle after electrical stimulation than at 50% duty cycle, the change of duty cycle didn't have any significant influence on CPK rate. In this regard, this study failed to come any consistent conclusion about the association between change of duty cycle and muscle fatigue. Therefore, it is advisable that follow-up studies seek various ways to a little more effectively apply electrical stimulation to laboratory animals by avoiding their muscle fatigue. GOT rate was significantly boosted up to 38.97% at 50% duty cycle after experiment (p<.05), while it was slightly increased to 1.68% at 20% duty cycle after experiment without any significant difference. Rather, GPT rate dropped slightly at both duty cycles after experiment, but there was not any significant difference. Although blood lactate and GOT were relatively less generated at 20% duty cycle after electrical stimulation than at 50% duty cycle, the change of duty cycle didn't have any significant influence on CPK rate. In this regard, this study failed to come any consistent conclusion about the association between change of duty cycle and muscle fatigue. Therefore, it is advisable that follow-up studies seek various ways to a little more effectively apply electrical stimulation to laboratory animals by avoiding their muscle fatigue.

• Industrial Engineering and Management Systems
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• v.12 no.1
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• pp.23-29
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• 2013

This paper presents inventory models for fresh agriculture products with time-varying deterioration rate. Due to the particularity of fresh agriculture products, the demand rate is a function that depends on sale price and freshness. The deterioration rate increases with time and is assumed to be a time-varying function. In the models, the inventory cycle may be constant or variable. The optimal solutions of models are discussed for different freshness and the deterioration rate. The results of experiments show that the profit depends on the freshness and deterioration rate of products. With the increasing inventory cycle, the sale price and profit increase at first and then start decreasing. Furthermore, when the inventory cycle is variable, the total profit is a binary function of the sale price and inventory cycle. There exist unique sale price and inventory cycle such that the profit is optimal. The results also show that the optimal sale price and inventory cycle depend on the freshness and the deterioration rate of fresh agriculture products.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.256-262
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• 2014

Cycle length of domestic nuclear power plants is determined by the demand-supply plan of utility company. The target cycle length is achieved by adjusting the number of feed fuel assembly and fuel enrichment. Traditionally, utility company first select the number of feed fuel assembly and then find out the fuel enrichment to achieve the special cycle length. But it is difficult to find out if this method is most economical than any other combinations of the enrichment and batch size satisfying the same cycle length. In this paper, core depletion calculation is performed to find out the optimum combination of the enrichment and batch size for given target cycle length in terms of fuel cycle cost using commercial core design code; CASMO/MASTER code. To minimize the uncertainty resulting from transition core analysis, levelized fuel cycle cost analysis was applied to the equilibrium cycle core in order to determine the optimum combination. The sensitivity study of discount rate was also carried out to analyze the levelized fuel cycle cost applicable to countries with different discount rates. From the levelized fuel cycle cost analysis results, the combination with smaller batch size and higher fuel enrichment becomes more economical as the discount rate becomes lower. On the other hand, the combination with higher batch size and lower fuel enrichment becomes more economical as the discount rate becomes higher.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.513-519
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• 2011

The object of this study is to investigate the performance characteristics of refrigerators using a single-circuit multi cycle and a bypass two-circuit multi cycle. Each refrigeration cycle was tested by varying secondary fluid mass flow rate and temperature. Based on the experimental data, the optimum refrigerant charge was 48 g and the COP at the optimum secondary fluid mass flow rate was 1.53 for the single-circuit multi cycle. For freezer(F)-only mode, both the single-circuit multi cycle and the bypass two-circuit multi cycle were operated at overcharge conditions, resulting in an increase of the secondary fluid mass flow rate. The maximum COPs of the single-circuit multi cycle and the bypass two-circuit multi cycle were 1.22 and 1.35, respectively. The COP increased by 10.7% with the application of the bypass two-circuit multi cycle.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.457-463
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• 2002

The closed cycle diesel engine is used in a closed circuit system which has no air breathing. The working fluid as intake mixture are consisted of oxygen, argon and recirculated exhaust gas in order to obtain underwater or underground power sources. In the present study, the high pressure diesel engine which can be operated by the closed cycle system with high intake pressure for increasing the net power rate is designed. It has been carried out to investigate the combustion characteristics of high pressure diesel engine according to the power rate. The maximum cylinder pressure and heat release rate were investigated. Also, major experimental data such as specific fuel consumption rate, oxygen concentrations, fuel conversion efficiency, polytropic exponent, and IMEP were compared with low pressure diesel engine experimental data.

• Journal of Applied Reliability
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• v.11 no.4
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• pp.433-445
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• 2011

Duty cycle is determined as the ratio of operating time to total time. Duty cycle in reliability prediction is one of the significant factors to be considered. In duty cycle application, non-operating time failure rate has been easily ignored even though the failure rate in non-operating period has not been proved to be small enough. Ignorance of non-operating time failure rate can result in over-estimated system reliability calculation. Furthermore, utilization of duty cycle in reliability prediction has not been evaluated in its effectiveness. In order to address these problems, two reliability models, such as MIL-HDBK-217F and RIAC-HDBK-217Plus, were used to analyze non-operating time failure rate. This research has proved that applying duty cycle in 217F model is not reasonable by the quantitative comparison and analysis.

• Journal of Embryo Transfer
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• v.31 no.3
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• pp.307-311
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• 2016

The aim of this study was to compare the appearance rate of vaginal cytology during estrous cycle in small pet bitches. A characteristic features of vaginal cytology during the estrous cycle were the high proportion of superficial cell in proestrus, anuclear cell in estrus, small intermediate cell in diestrus, and small intermediate cell in anestrus, respectively. There were no statistically significant differences of appearance rate of vaginal cytology among small pet bitches in the each phase of estrous cycle. These results indicated that the vaginal cytology was useful method for estimating estrous cycle and optimal breeding time in small pet bitches.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.252-256
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• 1989

In the low cycle fatigue fracture testing with KS(or JIS) SS41, crack growth rate, AE count rate and J-integral range are measured to get empirical relations between crack growth rate and J-integral range, AE count rate and J-integral range as well as AE count rate and crack growth rate. All the relations are shown to be linear on the log-log graphs. It is also shown that the linear relations can be formulated by using Dunegan's assumption and elastic-plastic fracture mechanics along with the well-known relation of crack growth rate and J-integral range. It is concluded that the differences between experimental and theoretical values are due to Dunegan's assumption.

• The Journal of Korean Obstetrics and Gynecology
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• v.23 no.2
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• pp.124-130
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• 2010

Purpose: The aim of the study was to investigate menstrual cycle phase differences in Heart Rate Variability(HRV) in dysmenorrhea patients. Methods: 16 dysmenorrhea patients were enrolled. The severity of dysmenorrhea was measured by Visual Analog Scale(VAS). Recordings for HRV analysis were obtained during the two phases of the menstrual cycle (follicular phase 4~10 days and luteal phase 18~23 days from the start of bleeding). Results: No measure of HRV was significantly different between two menstrual cycle phases. Conclusion: We concluded that menstrual cycle was not significantly associated with changes in autonomic nervous system as measured by HRV in dysmenorrhea patients.

• Journal of The Korean Society of Integrative Medicine
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• v.6 no.2
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• pp.17-23
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• 2018

Purpose : The purpose of this study was to investigate whether the respiratory cycle and posture can modulate the autonomic nervous system. Methods : Thirty-two healthy men and women, aged 20-30 years, were enrolled in this study. We conducted 2-second and 6-second respiratory cycle with the subjects in standing, sitting, and supine positions, respectively. Their heart rate variability was measured in each position for both cycle lengths. Results : The low frequency/high frequency (LF/HF) ratio is derived from heart rate variability. In the 2-second respiratory cycles, the LF/HF ratios were highest in standing, sitting, and supine position in descending order. There was a significant difference in heart rate between standing and sitting positions (P<.005). In addition, there was a significant difference in heart rate between standing and supine position (P<.000). In the 6-second respiratory cycles, the LF/HF ratios were again highest in a standing, sitting, and supine position in descending order. However, posture was not found to make a significant difference in this case. Conclusion : Respiratory cycle and posture effectively modulated the autonomic nervous system. Further studies of the clinical application of these results should be conducted.