• Journal of the Korean Association of Geographic Information Studies
• /
• v.6 no.2
• /
• pp.1-9
• /
• 2003

Surface solar radiation over the sea is estimated using the visible and infrared spin scan radiometer (VISSR) data onboard Geostationary Meteorological Satellite(GMS)-5 from January 1997 to December 1997 in clear and cloudy conditions. The hourly insolation is estimated with a spatial resolution of $5km{\times}5km$ grid. The island pyranometer operated by the Japan Meteorological Agency(JMA) is used to validate the estimated insolation. The root mean square error of the hourly estimated insolation is $104W/m^2$ with 0.91 of the correlation coefficient. In the variability of the hourly solar radiation investigated around the Korean Peninsula, the maximum value of solar radiation is found in June at the Yellow Sea and the East Sea, while in August at the South Sea because of low pressure conditions and front in June.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.4
• /
• pp.70-75
• /
• 2006

The performance of a turbopump system composed of an inducer, an impeller, a volute and seals has been computationally analyzed. To save the computational time, only one flow passage of the inducer and impeller is considered for the computations. A steady mixing-plane method is used on the impeller/volute interface for simulating the unsteady interaction phenomena. The axial thrust is predicted from the turbopump calculation in its entirety, which is necessary for such estimation. Moreover, the effects of each component on the pump performance are investigated at a design condition through the analysis of flow structures. The predicted performance is in good agreement with experimental data in terms of head rise, efficiency and volute wall pressure distributions despite of highly complex flow structures being present. The computational results also show that the axial and radial thrusts are within the design limit although corresponding experimental measurements were not taken.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.11
• /
• pp.951-956
• /
• 2008

The high temperature creep properties of the generating plant's high temperature tube, pipe and header and such are very significant in accordance with long-time exposure to the high temperature and pressure environment. Not only this, but as the welding procedure is compulsory for the cohesion of components, the creep properties regarding the local microstructures of steel weldment are very important. In order to understand the creep properties regarding the local microstructures of steel weldment, the SP-Creep test which is easy to get sample from the field component was conducted. The local microstructure of steel weldment, that is, W.M. and B.M.'s microstructures were observed using the SEM. The rupture time of W.M. was longer as 110 % averagely in a same condition, which is the consequence of the difference of the microstructure. Each lethargy coefficient of B.M. and W.M. is evaluated by the relation among the temperature, load and the rupture time from SP-Creep Test. The life estimation equation can be induced by the transformation of Power-law. B.M. and W.M. for each $550\;^{\circ}C$ and $575\;^{\circ}C$, the very similar to normal temperature of the domestic thermal power generation in working, are estimated.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.2 no.1
• /
• pp.69-75
• /
• 2004

DORT and ORIGEN2 code were used for calculation of neutron flux and inventory in reactor pressure vessel(RPV) of Kori unit-1, To calculate neutron flux using DORT code, the reactor was divided into 94 mesh from the center of core to RPV and from 0 to 45 degree along the azimuth. The cross-sections of main nuclides were recalculated using neutron flux in the RPV region. The results showed that 95% of the total activity in RPV came from the nuclides of $^{55}$ Fe, $^{60}$ Co, $^{59}$ Ni and $^{63}$ Ni. And the total activity with cooling of more than 50 years after decommissioning was no more than 0.2% of at the time of shutdown. Considering the weight of RPV is 210 tons, the initial total activity of RPV reached 5.25${\times}$10$^{6}$ GBq. To verify results of ORIGEN2 calculation, comparison between calculated and measured value at RPV of Kori unit-1 was peformed. The comparison results showed a good agreement.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.1
• /
• pp.62-68
• /
• 2016

A simple calculation tool for added resistance in waves is developed to utilize for initial design or embedded module for navigation support system. In order to select an appropriate calculation method for added resistance in waves, three methods (drift method, integrated pressure method, radiated energy method) based on strip method are applied to Wigley I and KVLCC2. The methods for added resistance in waves give the underestimated results because it is difficult to consider nonlinear effects due to reflected wave. We apply asymptotic (Faltinsen's method) and empirical formula (NMRI's method) to improve the accuracy for short wave length region. In comparison with experimental results, the combination of radiated energy method and short wave correction method of NMRI is the most reasonable. However, a simple sum of results calculated by two methods gives rise to the overestimation of added resistance for short wave length region because added resistance of radiated energy method exits in total reflection region. To overcome this problem, modified radiated energy method is proposed using correction coefficient defined by reflection coefficient of NMRI's method. Finally, added resistance in regular waves is composed of added resistance of modified radiated energy method and that of short wave correction method of NMRI. Estimated added resistance in regular waves is validated by comparison with experimental results of other research groups.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.10
• /
• pp.1229-1235
• /
• 2011

Fatigue tests were conducted on the aluminum alloy, A7075-T6 to determine the most reliable fretting fatigue damage parameter. Specimens with grooves were used, so that either fretting fatigue crack at the pad/specimen interface or plain fatigue crack at the groove could be nucleated, depending on the pad pressure. Both the crack nucleation location and initial crack orientation were examined using optical microscopy, and the results were used to assess the reliability of the various fretting fatigue damage parameters that have been most commonly used in the literature. Finite element analysis was employed to obtain the stress and strain data of the specimen, which were needed to estimate the parameter values and the orientation of the critical plane. It was revealed that both the Fatemi.Socie and McDiarmid parameters, which assume shear-mode fatigue cracking, are the most reliable.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.1
• /
• pp.124-131
• /
• 2002

In this study, a preliminary design code was developed for the initiation of HTPB/LOX hybrid rocket system. HTPB was assumed to have a constant regression rate. And initial input parameters; number of port, initial O/F ratio F/W ratio, and chamber pressure, were varied to analyze the effects on the performance and geometry of rocket system. The results showed a qualitatively good agreement with previous data. And it was revealed that there exists a number of design results that meet the mission requirements and that we could find an optimal design case if a proper constraint would be imposed. Thus, it is natural to account for the optimal algorithm during the design procedure and to consider more realistic and reliable formulations used for weight estimation of structural supports and accessories.

• Journal of Biomedical Engineering Research
• /
• v.20 no.2
• /
• pp.191-198
• /
• 1999

Biofeedback training is one of physiological self control methods for patients who has psychological problem and rehabilitational problem. It has been used to control blood pressure, heart rate, peripheral temperature, respiration, electromyography (ENG), and other biological signals-ENG, respiration, heat rate, peripheral temperature, skin conductance level-was developed in house. We applied this system to alcohol dependent patients to perform biofeedback training. In this experiment, the relaxation biofeedback training for alcohol dependent patient was carried out and the tension state for the change of biological signals were estimated using the fuzzy theory after relaxation biofeenback training. Eight alcohol dependent patients were agreed to participate in this experiment. Result showed that 1) the tension degree of patients were higher than the tension degree of normal subject. 2) The tension degree of patients were decreased as the training numbers were increased.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.4
• /
• pp.1-11
• /
• 2017

TPTF (Turbopump Real Propellant Test Facility) at Naro Space Center has used alcohol burner system to simulate the gas flow of gas generator of liquid rocket engine. During the test at TPTF, the temperature and pressure at turbine inlet were smoothly increased while those of the gas generator of engine were constant. Present research developed a simulation code for the burner and the piping system and applied to the system. The calculation results were in good agreement with the test, and confirmed quantitatively that the non-steadiness is due to the heat transfer of the pipe. While the insulation of the pipe is ineffective, the length has a large impact on the turbine inlet condition. The present research clarified the empirically estimation of test condition, and can be applied to determination of the following test conditions.

• Plant Journal
• /
• v.12 no.1
• /
• pp.24-28
• /
• 2016

In desulfurization facilities of oil-fired power plant, gypsum scale is attached in the absorber inner surface as the operating time increases. For this reason, the maximum possible load of the power generation is set down, resulting in further generation stop. Cleaning of absorber for scale removal can be determined at the time of setting down of the maximum possible load. In this study, 6 weeks before the maximum possible load of the power generation was down set, at the same time and desulfurization facilities outlet $SO_2$ concentration value was more than 130ppm, absorber differential pressure exceeded $380mmH_2O$, it was confirmed to be the time that has elapsed 44 weeks after the previous absorber cleaning. Cleaning time of the absorber was predicted to be a time which has elapsed 50 weeks from the previous cleaning time.