• Atmosphere
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• v.25 no.1
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• pp.51-66
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• 2015

This study was conducted to perform various sensitivity experiments using WRF (Weather Research and Forecasting) model in order to determine the effects of terrains of the Korean Peninsula and the land-sea thermal contrast on the formation and development of the convergent cloud band for the cases of 1 February 2012. The sensitivity experiments consist of the following five ones: CNTL experiment (control experiment), and TMBT experiment, BDMT experiment and ALL experiment that set the terrain altitude of Taeback Mountains and Northern mountain complex as zero, respectively, and the altitude of the above-mentioned two mountains as zero, and LANDSEA experiment that set to change the Korean Peninsula into sea in order to find out the land-sea thermal contrast effect. These experiment results showed that a cold air current stemming from the Siberian high pressure met the group of northern mountains with high topography altitude and was separated into two air currents. These two separated air currents met each other again on the Middle and Northern East Sea, downstream of the group of northern mountains and converged finally, creating the convergent cloud band. And these experiments suggested that the convergent cloud band located on the Middle and Northern East Sea, and the cloud band lying on the southern East sea to the coastal waters of the Japanese Island facing the East Sea, were generated and developed by different dynamical mechanisms. Also it was found that the topography of Taeback Mountains created a warm air advection region due to temperature rise by adiabatic compression near the coastal waters of Yeongdong Region, downstream of the mountains. In conclusion, these experiment results clearly showed that the most essential factor having an effect on the generation and development of the convergent cloud band was the topography effect of the northern mountain complex, and that the land-sea thermal contrast effect was insignificant.

• Journal of the Korean Solar Energy Society
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• v.32 no.4
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• pp.71-81
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• 2012

This study for the understanding of the radiation environment according to the altitude in urban area in the summer observes the long and short wave radiation environment at the 4 urban areas with different height and the 1 suburban area. The results of this study are as follows. (1) When the altitude was high, the more short wave radiation was observed. (2) As the altitude was high, the temperature of atmosphere got lower. And because of that the downward long wave radiation was also lower. This general trend was confirmed through the study. (3) Through the observation of long wave radiation, the upper atmosphere of suburban area had the atmosphere characteristic which the temperature was rising and decreasing faster. Therefore, the difference radiation characteristics between the urban and suburban area were confirmed. (4) The result of the ratio of short wave radiation to long wave radiation(short wave radiation/long wave radiation) according to the altitude and location, the value was increased when the distance was far from the artificiality structure or a heat source, and the urban effect became smaller. Thus, it is expected that the ratio will be an evaluation index for evaluating urbanization effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.80-87
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• 2005

T-50 supersonic jet trainer aircraft using digital flight-by-wire flight control system receives aircraft flight conditions such as altitude, VCAS(Calibrated Airspeed) and Angle of Attack from IMFP(Integrated Multi-Function Probe). IMFP sensors information have triplex structure using three IMFP sensors. Air-data selection logic is mid-value selection in three information from three IMFP sensors in order to have more reliability. From supersonic flight test at high altitude, air-data information is dropped simultaneously because of supersonic shock wave effect. This error information may affect to aircraft stability and safety in supersonic area at low altitude. This paper propose that sensitivity analysis and HQS(Handling Quality Simulator) pilot simulation in order to analyze flight stability and controllability in supersonic area at low altitude when these information is applied to flight control law.

• Journal of the military operations research society of Korea
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• v.34 no.1
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• pp.31-45
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• 2008

This paper describes a development of the operational architecture of a low altitude air defense automation system using a systems engineering approach. The future battlefield is changing to new system of systems that command and control by the network based BM/C4I. Also, it is composed of various sensors and shooters in an single theater. Future threats may be characterized as unmanned mewing bodies that the strategic effect is great such as UAVs, cruise missiles or tactical ballistic missiles. New threats such as low altitude stealth cruise missiles may also appear. The implementation of a low altitude air defense against these future threats is required to complex and integrated approach based on systems engineering. In this view, this work established an operational scenario and derived operational requirements by identifying mission and future operational environments. It is presented the operational architecture of the low altitude air defense automation system by using the CORE 5.0.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.986-993
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• 2018

Lateral thrust jet has better maneuverability performance than the control surface like the conventional fin for attitude control or orbital transition of guided weapons. However, in the supersonic region, a jet interaction flow occurs due to the lateral thrust jet during flight, and a complicated flow structure is exhibited by the interaction of the shock wave, boundary layer flow, and the vortex flow. Especially, hit-to-kill interceptors require precise control and maneuvering, so it is necessary to analyze the effect of jet interaction flow. Conventional jet interaction analyses were performed under low altitude conditions, but there are not many cases in the case of medium altitude condition, which has different flow characteristics. In this study, jet interaction flow analysis is performed on the lateral jet controlled interceptor operating at medium altitude. Based on the results, the structural characteristics of the flow field and the changes of aerodynamic coefficient are analyzed.

• Journal of Korea Multimedia Society
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• v.14 no.12
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• pp.1528-1535
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• 2011

We present a fog generation algorithm in 2D images. The proposed algorithm provides a scattering model for the approximated calculation of fog density. The scattering model needs parameters of distance and altitude information. However, 2D images do not include that information, so that we calculate them from the depth information generated in an interactive manner, and estimate the scattering factor by using the scattering model. Then we generate fog effect on an input image using the scattering factor by distance-oriented selection blur and color blending. With the algorithm, we can easily create the fog-effected images and fog generated animation from 2D images.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.749-755
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• 2012

The effect of elevation and meteorological elements is analyzed in Jeju Island for analysis of evapotranspiration with two different height observation station during 3 years data. The slope of temperature gradient recorded $1.30^{\circ}C$/100 m from the analysis of temperature data. There is much difference evapotranspiration between low elevation and high elevation station because of decrease solar radiation and wind speed with height increase. The evapotranspiration is observed by mini lysimeter at Hankukgonghang. The result of observation is presented 34.2% of global solar radiation changed into evapotranspiration during 4 clear days.

• Journal of Astronomy and Space Sciences
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• v.14 no.1
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• pp.87-93
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• 1997

Radiometers in UV and visible wavelengths were onboard the Korean Sounding Rocket(KSR)-1 and 2 which were launched on June 4th and September 1st, 1993. These radiometers were designed to capture the solar radiation during the ascending period of the rocket flight. The purpose of the instrument was to measure the vertical profiles of stratospheric ozone densities. Since the instrument measured the solar radiation from the ground to its apogee, it is possible to investigate the altitude variation of the measured intensity and to estimate the effect of atmospheric scattering by comparing the UV and visible intensity. The visible channel was a reference because the 450-nm wavelength is in the atmospheric window region, where the solar radiation is transmitted through the atmosphere without being absorbed by other atmospheric gases. The use of 450-nm channel intensity as a reference should be limited to the altitude ranges above the certain altitudes, say 20 to 25km where the signals are not perturbed by atmospheric scattering effects.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.62.3-63
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• 2017

The Mars Atmosphere and Volatile (MAVEN) mission has been providing valuable information on the atmospheric loss of Mars since its launch in November 2013. The Neutral Gass and Ion Mass Spectrometer (NGIMS) onboard MAVEN, was developed to analyze the composition of the Martian upper atmospheric neutrals and ions depending on various space weather conditions. We investigate a variation of upper atmospheric ion densities depending on the interplanetary coronal mass ejections (ICMEs). It is known that the Mars has a very weak global magnetic field, so upper atmosphere of Mars has been strongly affected by the solar activities. Meanwhile, a strong crustal magnetic field exists on local surfaces, so they also have a compensating effect on the upper atmospheric loss outside the Mars. The weak crustal field has an influence up to 200km altitude, but on a strong field region, especially east longitude of $180^{\circ}$ and latitude of $-50^{\circ}$, they have an influence over 1,400km altitude. In this paper, we investigated which is more dominant between the crustal field effect and the ICME effect to the atmospheric loss. At 400km altitude, the ion density over the strong crustal field region did not show a significant variation despite of ICME event. However, over the other areas, the variation associated with ICME event is far more overwhelming.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.427-430
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• 2006

The ground effect on tilt-rotor UAV is analyzed by simulating the hovering UAV for various altitudes. Ground effect increases pressure beneath the UAV body and generates additional lifting force. The ground effect diminishes at altitude 3m and hovering UAV generates constant lifting force above 3m.