• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.847-852
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• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feed-water heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare wall thinning range according to change entrance nozzle diameter and position with reference numerical analysis model's wall thinning range, various numerical analysis models applied. In case of changing diameter, four different diameter is applied. And a side of nozzle position, two different position-vertical type and parallel type-is applied. And then this paper describes operation of numerical analysis which is composed similar condition with real feed water heater. In conclusion, this study shows effective design for shall wall thinning by changing nozzle diameter and position.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.2
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• pp.112-120
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• 1996

The effects of ${\varepsilon}$ martensite content and strain amplitude on damping capacity of an Fe-17%Mn alloy have been studied to establish damping mechanism of Fe-Mn system corresponding to the magnitude of strain amplitude. In a range of $1{\times}10^{-4}{\sim}3{\times}10^{-4}$ strain amplitude, the damping capacity is linearly proportional to the ${\varepsilon}$ martensite content, which suggests that stacking faults and ${\varepsilon}$ martensite variant boundaries are the principal damping sources. In the range of $4{\times}10^{-4}{\sim}6{\times}10^{-4}$ strain amplitude, however, a maximum damping capacity is observed around 68 vol.% ${\varepsilon}$. This behavior is very similar to dependence of relative area of ${\gamma}/{\varepsilon}$ interface on ${\varepsilon}$ martensite content. This means that in this strain range, ${\gamma}/{\varepsilon}$ interface acts as damping source in addition to the stacking faults and variant boundaries in Fe-17%Mn alloy.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.279-284
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• 2014

PURPOSE: This study intended to verify whether there was actual correlation between weight-bearing asymmetry and a limitation in hip joint rotation range in patients with low back pain. METHODS: Thirty five low back pain patients voluntarily participated this study. For each participant, hip joint medial rotation symmetry rate and the weight-bearing symmetry rate were calculated. The correlation between the two variables was investigated. RESULTS: A decrease in the left hip joint medial rotation range of motion (ROM) was observed more often than a reduction in the right hip joint medial rotation ROM. However, similar number between right and left side was observed in ground reaction force more weighted. The coefficient between the passive hip joint medial rotation symmetry rate and the weight loading symmetry ratio was -0.19 (p < 0.05). CONCLUSION: The present study demonstrated a weak correlation between the hip joint medial rotation ROM and the weight distribution of both feet. Such result suggests that careful evaluation by separating each element is needed in treating patients with low back pain. Future research should take into account asymmetric alignment and abnormal movement in different joints of the body as well as asymmetry in the bilateral hip joint rotation and the unilateral weight supporting posture.

• Journal of Veterinary Clinics
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• v.34 no.4
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• pp.241-244
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• 2017

The purpose of this study was to evaluate the concurrent validity of the double meter inclinometer (DMI) for passive joint range of motion (ROM) in beagle dogs and to compare these results to a universal plastic goniometer (UPG). Fifteen beagle dogs were recruited for this study. Joint ROM was evaluated twice with each device to calculate the intraobserver reliability. The intraclass correlation coefficient (ICC) values of the UPG were good to excellent (> 0.75) for all joint ROM tests. Similar results were obtained with the DMI. The ICC values of the DMI were good to excellent (> 0.75) except in extension of the tarsal joint (ICC = 0.69). The majority of the ICC results between each device were poor (< 0.50) with the exception of six joints. Our findings suggest that the inclinometer can be used for passive joint ROM in veterinary medicine. However, caution should be taken when comparing measured values of passive joint ROM obtained utilizing both the DMI and UPG.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.183-186
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• 2007

The spectroscopic properties of bright extragalactic planetary nebulae are reviewed, considering primarily their chemical abundances and their internal kinematics. Low-resolution spectroscopy is used to investigate how the precursor stars of bright planetary nebulae modify their original composition through nucleosynthesis and dredge up. At present, the evidence indicates that oxygen and neon abundances usually remain unchanged, helium abundances are typically enhanced by less than 50%, while nitrogen enhancements span a very wide range. Interpreting these changes in terms of the masses of their progenitor stars implies that the progenitor stars typically have masses or order $1.5M_{\bigodot}$ or less, though no models satisfactorily explain the nitrogen enrichment. High-resolution spectroscopy is used to study the internal kinematics of bright planetary nebulae in Local Group galaxies. At first sight, the expansion velocities are remarkably uniform, with a typical expansion velocity of 18 km/s and a range of 8-28 km/s, independent of the progenitor stellar population. Upon closer examination, bright planetary nebulae in the bulge of M31 expand slightly faster than their counterparts in M31's disk, a result that may extend generally to the planetary nebulae arising from old and young stellar populations. There are no very strong correlations between expansion velocity and global nebular properties, except that there are no large expansion velocities at the highest $H{\beta}$ luminosities (i.e., the youngest objects never expand rapidly). These results independently suggest that bright planetary nebulae arise from a similar mass range in all galaxies. Nonetheless, there are good reasons to believe that bright planetary nebulae do not arise from identical progenitor stars in all galaxies.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.383-391
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• 2009

Vibrations at different frequencies with a different intensity as well as a pressure pulsation with different parameters are two phenomena which can be observed at different water turbines. Due to the vibration and the pressure pulsation some restrictions of water turbine operation range are applied. Similar problems with the efficiency level in a wide water turbine operation range are the basic problems which are solved for ages. A theoretical and practical solution of the above mentioned problems is very much time and money consuming. The paper describes a new theoretical solution of the excitation and pressure pulsation decrease as well as extension of the operational range with high efficiency level. The new concept to decrease the vibrations and pressure pulsations is based on a heterogeneous runner blade geometry generation. The new concept of the runner geometry design was numerically tested at a low specific speed pump turbine, see Fig. 1, and basic points of the concept are presented in this paper.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.5-12
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• 2010

Comparative study on the flow measurement by 5-hole and 7-hole probes was conducted in a linear cascade with tip clearances of 2.3%, 3.1%, and 4.4% of the blade span. Calibration range of the 5-hole and the 7-hole probes were ${\pm}25$ and ${\pm}50$ degrees, respectively. Results show that the secondary flow and total pressure loss measured by the 5e-hole and 7-hole probes were similar at small tip clearance cases. However, at the tip clearance of 3.1% and 4.4% of the blade span cases, flow angles exceeding the calibration range of the 5-hole probe were observed. Because of the wider calibration range, larger flow angle by strong leakage vortex could be measured by the 7-hole probe.

• Textile Coloration and Finishing
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• v.9 no.5
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• pp.1-9
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• 1997

In the single yarn spinning process by the ring spinning system, the finer the fineness of yarn and the lower the twist coefficient, the lower the breaking strength and breaking elongation. The change of yarn specific volume to yarn number agreed with Peirce's formula in the range of Ne 50 to 70, but above that range the values of the experiment are higher than that of the formula. The change of diameter of yarn to the reciprocal of the square root of yarn number agreed with Peirce's formula in the range of under 0.14, but above that value the values of the experiment are higher than that of the formula. In breaking strength variation according to twist constant of single yarn, as the twist coefficient increased, breaking strength increased. At 5.8∼6.0 of twist coefficient the maximum breaking strength was shown, but above that value breaking strength decreased. Breaking elongation also showed a similar tendency. But at 6.0∼6.5 of twist coefficient the maximum breaking elongation was shown. Also spinning tension increased as twist coefficient increased. Twist coefficient, breaking strength and breaking elongation according to the number of coils stayed almost the same. Yarn spinning tension according to the number of coils at the maximum of diameter was the lowest value. The speed of the traveller at the maximum of diameter was the highest value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.3
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• pp.315-323
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• 1998

This paper contains a verification of simulation program to predict the capacity of a condenser used in car air-conditioners. Verification of simulation program is carried out with the comparison error between experiment and simulation bounds within 3.5%. The present investigation shows the results for heat transfer rates of condenser under different operating conditions, such as velocity and degree of superheat. The range of front velocity of air is 1∼5m/s. As the front velocity is increased, the heat transfer rate of condenser is largely increased at a low velocity range. In a meanwhile, heat transfer rate of condenser is almost constant in a range of velocity over 3m/s. As for the effect of inlet pressure of refrigerant on the heat transfer rate, we obtained the similar trend of heat transfer rates as like varying the front velocity, Also we have calculated the heat transfer rates with varying inlet superheats of refrigerant, the larger the superheat is, the more heat transfer rate is obtained.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.125-128
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• 2000

The conventional fractal decoding was required a vast amount computational complexity. Since every range blocks was implemented to IFS(iterated function system). In order to improve this, it has been suggested to that each range block was classified to iterated and non-iterated regions. If IFS region is contractive, then it can be performed a fast decoding. In this paper, a searched region of the domain in the encoding is limited to the range region that is similar with the domain block, and IFS region is a minimum. So, it can be performed a fast decoding by reducing the computational complexity for IFS in fractal image decoding.