• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1953-1958
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• 2007

This paper presents the results of a series of performance tests for the integral Stirling cryocooler. Infrared sensor systems incorporating cryocoolers are required to be qualified to the appropriate environmental specification. Integral Stirling cryocooler for thermal imaging system have matured to the stage of undergoing formal qualification test program. The thermal environmental test of the Stirling cryocooler is presented in this paper. We performed that low and high temperature keeping test from $-40^{\circ}C$ to $+71^{\circ}C$ and operating test at high and low temperature cyclic range with acceptance tests performed at scheduled intervals. Cooldown time to 80K and steady state input power at 80K were determined as a function of cooler components temperatures at the compressor, hot end and cold tip. Tests performed on this cooler have been successful with a measured cooldown time to 80K of less than 5 minutes 24seconds for $71^{\circ}C$ ambient temperature with input power of 11W

• The Journal of Korean Physical Therapy
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• v.17 no.2
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• pp.11-22
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• 2005

Purpose: The purpose of this study was to investigate the effects of aquatic health exercise program for the old. Methods: 20 healthy female with an average age of 71years($71{\pm}4.2$), were participated in this study. The aquatic health exercise program that include warm-up, stretching, strengthening exercise, WATSU and cool-down was performed in the pool two times a week for eight weeks(40min per one session). Body composition, strength of the both knee flexors and extensors, balance ability(sway area and path), whole body reaction time and flexibility(forward reaching test in long sitting) were measured before and after exercise. The data was analyzed with paired t-test to determine significant differences of all suggested factors between pre and post-exercise by make use of the SPSS(ver 10.0) package program. Results: The strength of the both knee flexors and extensors were increased significantly(right knee; p<0.01, left knee; p<0.05). Anteroposterior sway area (p<0.01), and sway path (p<0.001) of both leg were reduced significantly with eyes closed and opened. Whole body reaction time by optical stimulation was increased significantly (p<0.01) but whole body reaction time by auditory stimulation was no significant difference. The flexibility was increased significantly (p<0.01). Conclusion: Aquatic health exercise program can improve muscle strength, balance, whole body reaction, and flexibility.

• Journal of Life Science
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• v.14 no.4
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• pp.573-576
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• 2004

The purpose of the present study is to investigate the lipid peroxidation, creatine kinase activity and cortisol hormone levels following the training intensity in elite judo players. Six elite Judo players participated in the experiments (3h repetition judo program), which include stretching, judo skill practice and cool down without recess. Blood sampling were taken at the judo gymnasium at the time of resting, 1h training, 2h training, 3h training, 2h recovery, and 24h recovery time and this were analyzed for CK, MDA and Cortisol levels. The results obtained were analyzed via repeated measures of ANOVA using SPSS package program (ver.10.0) and a value of p<.05 was considered statistically significant. The results from this study were as follows. In the CK levels, which reflect the contribution of creatine phosphate and muscle damage degree, there was a significant difference (p<.05) after judo training in every period. Recovery 24h showed the highest level. In the MDA levels, which reflect lipid peroxidation, there was a significant difference (p<.05) after judo training. Recovery 2h showed the lowest level. In the cortisol hormone levels, which reflect stress status, there was a significant difference (p<.05). In this study, we can conclude that For the trained athletes, MDA level was lower at the time of exercise compare to the other period, this is caused by the increased antioxidant defence mechanism.

• The Journal of Korean Physical Therapy
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• v.29 no.4
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• pp.201-206
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• 2017

Purpose: The aim of this study was to identify the effects of Pilates mat exercise may improve trunk muscle thickness and balance in healthy adults. Methods: Eighteen healthy adults participated in this study. They were randomly assigned to one of two groups: Pilates mat exercise group (n=9) and the control group (n=9). Subjects in Pilates mat exercise group performed the exercises three days per week for 6 weeks, which consisted of warm up, main workout, and cool down. Trunk muscle thickness of the rectus abdominis (RA), internal oblique (IO), external oblique (EO), transverse abdominis (TrA), multifidus (MF), and erector spine (ES) were measured using an ultrasonography. Balance ability was evaluated using Romberg test and limits of stability (LOS). Measurements were performed before training, 3 weeks after training, and 6 weeks after training. Results: There was a significant difference of RA, EO, IO, MF, and ES according to the main effect of time (p<0.05). There was a significant difference of EO, MF, ES, Romberg, and LOS according to interaction effect between the time and group (p<0.05). There was a significant difference only for LOS according to the main effect of the group (p<0.05). Conclusion: Pilates mat exercise did increase trunk muscle thickness and balance. However, the effect with respect to trunk thickness was limited. Pilates mat exercise appears to be more effective in improving muscles related to trunk extension and balance.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.3
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• pp.525-534
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• 2014

This study has examined the effect of after-school physical activity on body composition and health related fitness of middle school students. The duration of after-school physical activity training program of this study is 12 weeks, the training time in 1 hours warming-up 10 minutes, the skill training 45 minutes and cool down did in 5 minutes. Exercise frequency is 5 time per week. Height basketball class, soccer class, subject class showed statistically meaningful increase between group variance showed statistically meaningful. Weight basketball class, soccer class, showed statistically meaningful decrease. Muscle mass basketball class showed statistically meaningful increase, soccer class showed statistically meaningful decrease. Cardiopulmonary basketball class, soccer class, showed statistically meaningful decrease. Explosive muscular strength basketball class, soccer class, showed statistically meaningful decrease. subject class showed statistically meaningful increase, between group variance showed statistically meaningful. Flexibility basketball class showed statistically meaningful increase, soccer class. Muscular strength basketball class, soccer class, subject class showed not statistically meaningful different.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.101-108
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• 2008

Residual stress is one of the causes which make defects in engineering components and materials. Many methods have been developing to measure the residual stress. Though these methods provide the information of the residual stress, they also have disadvantage like a little damage, time consumption, etc. In this paper, we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry and spot heating. The speckle pattern interferometer measures in-plane deformation during the heat provides for much localized stress relief. 3-D shape is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heat and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, we could experimentally confirm that residual stress can be measured by using laser interferometry and spot heating method.

• Transactions of Materials Processing
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• v.26 no.1
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• pp.35-40
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• 2017

Laser forming is an advanced process in sheet metal forming in which thermal stress originated from the laser heat source is used to shape the metal sheet. However, substantial waiting time is normally necessary for the workpiece to cool down between consecutive scans so that a steep temperature gradient can be reestablished in the next scan. In order to solve this drawback, laser bending characteristics are experimentally implemented in underwater condition. Laser forming effects under various conditions, including different laser power, scanning velocity, beam diameter, number of passes and material, are investigated. The results show that the underwater laser forming facilitates deliberate forming. The bending angle per respective laser scan is decreased with increasing the number of passes and scanning velocity.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.220-228
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• 2002

The cool-down performance after soaking is very important in an automotive air-conditioning system and is considered as a key design variable. Therefore, transient characteristics of each system component are essential to the preliminary design as well as steady-state performance. The objective of this study is to develop a computer simulation model and ostinato theoretically the transient performance of an automotive air-conditioning system. To do that, the mathematical modelling of each component, such as compressor, condenser, receiver/drier, expansion valve, and evaporator, is presented first of all. The basic balance equations about mass and energy are used in modelling. For detailed calculation, condenser and evaporator are divided into many sub-sections. Each sub-section is an elemental volume for modelling. In models of expansion valve and compressor, dynamic behaviors are not considered in this analysis, but the quasisteady state ones are just considered, such as the relation between mass flow rate and pressure drop in expansion device, polytropic process in compressor, etc. Also it is assumed that there are no heat loss and no pressure drop in discharge, liquid, and suction lines. The developed simulation model is validated by comparing with the laboratory test data of an automotive air-conditioning system. The overall time-tracing properties of each component agreed well with those of test data in this case.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.205-213
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• 1987

A linear thermoviscoelastic material model, whose basis is on incremental constitutive equation that takes complete strain and temperature histories into account, is derived and computerized in the finite element code. The thermoviscoelastic F.E.M. code which is intended primarily to analyze the cylinder model during the cool-down period, embodies the assumption of linearly elastic bulk and visco-elastic shear responses, thermo-rheologically simple response to temperature change and isotropic thermal expansion. The verification of computer program is accomplished by first testing it against a closed form solution of A.M. Freudenthal & M. Shinozuka's. The stress and strain analyses of five cylindrical models are presented and compared with experimental results. Analytical results are good agreement with experimental results. Margins of safety are evaluated and its allowable ranges are presented.

• Nuclear Engineering and Technology
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• v.36 no.5
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• pp.388-402
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• 2004

A phenomena identification and ranking table(PIRT) was developed for a main steam line break (MSLB) event for the Advanced Power Reactor-1400 (APR-1400). The selectee event was a double-ended steam line break at full power, with the reactor coolant pump running. The developmental panel selected the fuel performance as the primary safety criterion during the ranking process. The plant design data, the results of the APR-1400 safety analysis, and the results of an additional best-estimate analysis by the MARS computer code were used in the development of the PIRT. The period of the transient was composed of three phases: pre-trip, rapid cool-down, and safety injection. Based on the relative importance to the primary evaluation criterion, the ranking of each system, component, and phenomenon/process was performed for each time phase. Finally, the knowledge-level for each important process for certain components was ranked in terms of existing knowledge. The PIRT can be used as a guide for planning cost-effective experimental programs and for code development efforts, especially for the quantification of those processes and/or phenomena that are highly important, but not well understood.