• Korean Journal of Remote Sensing
• /
• 제33권6_3호
• /
• pp.1179-1185
• /
• 2017

The KOMPSAT-3A satellite acquires high-resolution MWIR images twice a day compared to conventional Earth observing satellites. New radiometric information of Earth's surface can be provided due to different characteristics from existing SWIR images or TIR images. In this study, the difference image of multitemporal images was generated and compared with existing infrared images to find the characteristics of KOMPSAT-3A MWIR satellite images. A co-registration was performed and the difference between pixel values was minimized by using PIFs (Pseudo Invariant Features) pixel-based relative normalization. The experiment using Sentinel-2 SWIR image, Landsat 8 TIR image, and KOMPSAT-3A MWIR image showed that the distinction between artifacts in the difference image of KOMPSAT-3A is prominent. It is believed that the utilization of KOMPSAT-3A MWIR images can be improved by using the characteristics of IR image.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.22-29
• /
• 2011

Critical speed of high thrust liquid rocket engine turbopump is obtained through a rotordynamic analysis and a unloaded turbopump test is peformed for validation of the numerical model. The first critical speed predicted by the numerical analysis is correlated well with the test result for the bearing unloaded rotor condition only considering mass unbalance load. Using the previous rotordynamic model, critical speed variation is estimated as a function of varied bearing stiffness due to pump and turbine radial loads with relative angle difference. From the numerical analysis, it is found that the relative angle difference of pump and turbine radial loads greatly affects the critical speed. However, additional axial load reduces the effect derived from the relative angle difference of radial loads.

• Journal of Astronomy and Space Sciences
• /
• 제25권3호
• /
• pp.283-290
• /
• 2008

Satellite formation flying can provide the platform for interferometric observation to acquire the precise data and ensure the flexibility for space mission. This paper presents development and verification of an algorithm to estimate the baseline between formation flying satellites. To estimate a baseline(relative navigation) in real time, EKF(Extended Kalman Filter) and UKF(Unscented Kalman Filter) are used. Measurements for updating a state-vector in Kalman Filter are GPS single difference data. In results, The position errors in estimated baseline are converged to less than ${\pm}1m$ in both EKF and UKF. And as using the two types of Kalman filter, it is clear that the unscented Kalman filter shows a relatively better performance than the extended Kalman filter by comparing an efficiency to the model which has a non-linearity.

• Food Science and Preservation
• /
• 제8권3호
• /
• pp.269-273
• /
• 2001

Apples and pears for investigating the optimal storage conditions were purchased from the farmhouse located in Hadong-Goon and Geochang-Goon Gyeongnam just before the beginning of this experiment. Apples and pears were, stored under 70%(storage temperature : 25$^{\circ}C$), 80%(10$^{\circ}C$) and 90%(5$^{\circ}C$) of relative humidity, respectively and their qualities in microbial counts, decay ratio, surface color difference and chemical attributes were monitored during the storage period. Apples and pears stored under 70% of relative humidity showed the minimal change in weight lass, decrease ratio of ascorbic acid content, surface color difference and degrees contaminated by putrefactive microorganisms. As the results of this experiment, apples and pears stored under 90% of relative humidity showed the optimal storage conditions for maintaining their freshness.

• The Journal of the Korea Contents Association
• /
• 제9권6호
• /
• pp.370-378
• /
• 2009

This study researched on job-esteem of the students who are majoring in aviation operation services. Examining the differences in feelings of job-esteem on one's university and grade level, firstly, the result among universities indicated that the difference in positive value and social reputation factors but there's no difference in negative treatment and relative profit factors. secondly, the result indicated that there is a difference in feelings of job-esteem based on one's grade level in positive value, social reputation, and negative treatment except relative profit factors. Also, the result of this study on how variables of population statistics and satisfaction on the college major and self-esteem as flight attendants affect subordinate factors of job-esteem showed only variables of satisfaction on college major affected positive value, social reputation, negative treatment, relative profit factors.

• Journal of the Korean Society of Propulsion Engineers
• /
• 제16권4호
• /
• pp.42-49
• /
• 2012

Critical speed of high thrust liquid rocket engine turbopump is obtained through a rotordynamic analysis and a unloaded turbopump test is peformed for validation of the numerical model. The first critical speed predicted by the numerical analysis is correlated well with the test result for the bearing unloaded rotor condition only considering mass unbalance load. Using the previous rotordynamic model, critical speed variation is estimated as a function of varied bearing stiffness due to pump and turbine radial loads with relative angle difference. From the numerical analysis, it is found that the relative angle difference of pump and turbine radial loads greatly affects the critical speed. However, additional axial load reduces the effect derived from the relative angle difference of radial loads.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• 제6권1호
• /
• pp.125-137
• /
• 1996

This study was designed to investigate effects of relative humidity on the breakthrough of charcoal tubes at a fixed vapor concentration and sampling time during mixed organic vapor sampling. A vapor generator was used to generate three different concentrations of mixed organic vapor and a stainless steel chamber was fabricated and utilized to maintain three different percentages of relative humidity while maintaining a constant temperature. The results were as follows; 1. At high relative humidity, breakthrough of mixed organic vapor occurred quickly at low vapor concentration than at high vapor concentration because of the reduced adsorption volume of charcoal tube due to humidity. 2. Breakthrough by competitive adsorption of vapors onto charcoal tube was observed at first from n-hexane having the lowest boiling point and highest vapor pressure among the three organic vapors investigated, followed by TCE. No breakthrough was observed from toluene under all experimental conditions. 3. For n-hexane, breakthrough was observed after 2 hours of sampling and breakthrough rates were increased as relative humidity increased. For TCE, breakthrough was found after 3 hours of sampling and breakthrough rates by sampling time were increased as vapor concentration increased. 4. The adsorbed amount of mixed organic vapor at breakthrough was shown to have statistically significant correlations with sampling time, relative humidity, and vapor concentration in descending order of correlation. Relative humidity and sampling time for n-hexane and sampling time and concentration for TCE were both statistically significantly correlated. 5. Relative humidity was found to affect the amount of breakthrough of mixed organic vapor and n-hexane. Among three percentages of relative humidity investigated, the amount of breakthrough at 85 % relative humidity was significantly larger than those of at lower percentages of relative humidity. No statistically significant difference was found between 25 % and 55 % relative humidity. 6. The results of multiple regression analysis between breakthrough and relative humidity, vapor concentrations showed that the coefficient of determination of mixed organic vapor was 0.263 and those of n-hexane and TCE were 0.275 and 0.189, respectively. 7. Flow rates of sampling pumps used were found to be affected by relative humidity present. At 25 %, 55 %, and 85 % relative humidity, the relative errors of sampling pump were 1.4 %, 13.4 %, and 18.6 %, respectively. In conclusion, the results of this study showed that high relative humidity could reduce the adsorption volume of charcoal tubes and subsequently increase breakthrough rates. Therefore, to prevent breakthrough when sampling mixed organic vapors, it is suggested that either sampling volume be reduced on the flow rate be lowered so as to minimize breakthrough of the most volatile organic vapor in the mixture. In addition, since the flow rates of a sampling pump can be adversely affected by high relative humidity, it is recommended to use a constant flow mode pump when sampling in the highly humid environment.

• Journal of The Korean Society of Grassland and Forage Science
• /
• 제12권4호
• /
• pp.226-231
• /
• 1992

This experiment was carried out to estimate the dry matter accumulation using growth analysis in spring growth of perennial ryegrass varieties grown under space planting conditions, based on the data of previous paper9'. The results obtained were as follows: 1. Growth parameters of leaf area ratio(LAR), specific leaf area(SLA) and leaf weight ratio(LWR) were recognized siginificant differences between varieties. But, specific leaf area(SLA), leaf weight ratio (LWR) and relative tiller appearance rate(RTAR) were recognized significant differences between growth stages. Specific leaf area(SLA) was significant difference for the interaction of variety Xgrowth stage. 2. The relative growth rate of biological yields(BYRGR) indicated significantly positive correlations with relative growth rate of shoot(RGR) and root(RWGR), and net assimilation rate(NAR) as affected by the varieties and growth stages. 3. The relative growth rate of biological yields(BYRGR) indicated significantly positive correlation with nct assimilation rate(NAR) in all varieties. Leaf area ratio(LAR) had significantly positive correlation with specific leaf area(SLA) in all varieties, but shows a significant negative correlation with leaf weight ratio(LWR) of Maprima variety. 4. The relative growth rate of biological yields(BYRGR) indicated significantly positive correlations with the absolute growth rates of yield components.

• Asian Journal of Turfgrass Science
• /
• 제15권3호
• /
• pp.111-118
• /
• 2001

We observed air temperature and relative humidity in the green space why this research graspes effect of climate relax by coverage condition and height difference tree in green space of the 4ha scale. With this data, analyzed relationship of coverage and air temperature or relative humidity distribution, number of tree and climate relax by revolution analysis. In this result, higher zone formed barren area, lower zone did forest and surround grassland. Relative humidity have corresponding type of air temperature distribution. higher air temperature zone was lower humidity and lower zone was higher humidity. Coverage condition effect climate relax by increasing forest and grassland. and increasing number of tree effect climate relax no related hight of tree. This efficiency order of an arbor, subarbor.

• Journal of Biosystems Engineering
• /
• 제30권2호
• /
• pp.110-113
• /
• 2005

Relative humidity of air In the greenhouse has to be maintained at 70 to 80 percents to provide a better growth condition of crops. To control relative humidity of air in the greenhouse, a dehumidifier functioning by refrigeration cycle was designed and manufactured in this study. And, results of its performance test in the greenhouse site were reported. The developed dehumidifier has separated condenser and evaporator in the heat exchanger part in order to increase dehumidifying capacity at a low temperature condition. When the conditions of incoming air into the dehumidifier were temperature of $15\~25^{\circ}C$ and relative humidity of $0\~95\%$, quantity of condensed water per hour, ie, dehumidification rate was $4.7\~7.0\;kg/hr$. Relative humidity difference was not greater than 5 percents at various locations in the greenhouse due to proper distributing of dehumidified air through vinyl duct. Thermal energy output from the developed dehumidifier was about 8,5000 kcal/hr that was 7 percents of maximum greenhouse heating load of 10 a.