• Communications of Mathematical Education
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• v.20 no.1 s.25
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• pp.9-18
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• 2006

In this paper we study on concept analogy of altitude and escribed circle of triangle. We start from following theorems related with sides of triangle: existence of triangle, Pythagoras theorem, cosine theorem, Heron formula. Using concept analogy of sides-altitudes, altitudes-escribed circle's radii we discover some properties of altitude and escribed circle's radii and prove these properties.

• Advances in aircraft and spacecraft science
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• v.8 no.1
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• pp.1-15
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• 2021

Mars exploration demands aerodynamic computations for a proper design of missions of spacecraft carrying instruments and astronauts to Mars. Both Computational Fluid Dynamics (CFD) and Direct Simulation Monte Carlo (DSMC) method play a key role for this purpose. To the author's knowledge, the altitude separating the fields of applicability of CFD and DSMC in Mars atmosphere entry is not yet clearly defined. The limitations in using DSMC at low altitudes are due to technical limitations of the computer. The limitations in using CFD at high altitudes are due to thermodynamic non-equilibrium. Here, this problem is studied in Mars atmosphere entry, considering the Mars Pathfinder capsule in the altitude interval 40-80 km, by means of a DSMC code. Non-equilibrium is quantified by the relative differences between translational temperature and: rotational (θt-r), vibrational (θt-v), overall (θt-ov) temperatures, anisotropy is quantified by the relative difference between the translational temperature component along x and those along y (θx-y) and along z (θx-z). The results showed that θt-r, θt-v, θx-y, θx-z are almost equivalent. The altitude of 45 km should be the limit altitude for a proper use of a CFD code and the altitude of 40 km should be the limit altitude for a reasonable use of a DSMC code.

• Journal of Veterinary Clinics
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• v.24 no.1
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• pp.1-4
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• 2007

Despite the risk of high altitude disease (HAD), raising cattle at higher altitudes does have advantages such as beef quality due to minimal chance of infection and stress. The ideal situation is to determine the optimum altitude suitable for raising cattle while at the same time minimizing the risk of HAD. Therefore, in this study, we documented the health status of three groups of steers, raised at three different altitudes (200m, 400m and 800m) in Gangwon province, using routine hematological, biochemical and hormonal tests. The red blood cell counts and hemoglobin concentration were highest in the 800m group, and lowest in the 200m group, possibly due to hypoxia induced myeloid and erythroid stimulation. The mean concentration of AST, BUN and serum cortisol were lowest in the 800m. These findings suggest the stress factor will contribute the general health status of animal and indicate a difference in the Hanwoo groups raised at 800m compared to 200m, where the cattle raised at the higher altitude exhibit better health status compared to the lower altitude, possibly due to less stressful environment in the higher altitude.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.959-961
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• 2003

Cirrus clouds observation was conducted using a lidar system in order to measure their height, thickness and optical depth at Kwangju (35$^{\circ}$10'N, 126$^{\circ}$53'), Korea in winter, December 2002, and spring March and April 2003. Cirrus clouds at high altitude can be distinguished from atmospheric aerosols location by high depolarization ratio and high altitude. Cirrus clouds were observed at 5${\sim}$12km altitudes with a high depolarization ratio from 0.2 to 0.5. Optical depth of cirrus clouds had varied from 0.28 to 1.81. Radiative effect of observed cirrus cloud on climate system was estimated to be negative net flux from ?0.24 to ?31.04 W/m$^{2}$.

• Korean Journal of Environment and Ecology
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• v.22 no.5
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• pp.530-535
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• 2008

This study was carried out to analyze the vegetation and soil characteristic, and ordination of Wasabia japonica population at Ulleung-Do. The Wasabia japonica population is distributed in altitudes of 440m to 570m at Seo-Myon and also in altitudes of 340m near Nari-valley. In the study sites, soil organic matter, nitrogen, available phosphorous, exchangeable potassium, exchangeable calcium, exchangeable magnesium concentration, cation exchange capacity, and soil pH were 15.01%, 0.48%, 44.19ppm, 2.00(me/100g), 7.19(me/100g), 4.44(me/100g), 22.55(me/100g), and 6.17, respectively. The Rumohra standishii dominant population was mainly found in high in soil nitrogen, organic matter, CEC, and exchangeable calcium concentration in comparison with Boehmeria spicata dominant population. The Boehmeria spicata dominant population was mainly found in high in soil pH.

• Korean Journal of Oriental Medicine
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• v.14 no.1
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• pp.117-121
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• 2008

Objectives : This study was carried out to investigate vegetation structure of Adenophora remotiflora population found to be distributed in Jeombongsan Danmokryeong. Methods : From 2007 June until November, $2m{\times}2m$ quadrat was established in Adenophora remotiflora community in order to record a dominants and coverage. Results : 1. The vegetation of Adenophora remotiflora community was classified into Astilbe chinensis subcommunity and Calamagrostis langsdodfii subcommunity. Differential species of community was Angelica deacrusica and Lychnis cognata. The Adenophora remotiflora community was found in south face, high of altitude and low slope degree. 2. The value of species diversity ranged from 5.547152 to 10.077886, euenness ranged from 0.779749 to 0.986358 and dominance ranged from 0.013642 to 0.220251. 3. Aconitum jaluense was located at the higher altitudes than those of other species. Lychnis cognata, Lychnis cognata and Pedicularis resupinata was located at the lower altitudes and slope degree than those of other species. Conclusions : The vegetation of Adenophora remotiflora community was classified into Astilbe chinensis subcommunity and Calamagrostis langsdodfii subcommunity. The value of species diversity was low and community was dominated by a large number species. The Adenophora remotiflora community was found in south face, high of altitude and low slope degree.

• Journal of The Korean Astronomical Society
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• v.29 no.2
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• pp.245-253
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• 1996

We have analyzed infrared (IR) images of Jupiter which was observed at the McDonald Observatory, Texas, U.S.A., during the P/SHoemaker-LEvy 9 (SL9) impact period and about one week after the last impact. The IR images were obtained on the 2.7m telescope using a NICMOS array with filters to isolate the $1.5{\mu}m\;NH_3\; band,\;the\;2.3{\mu}m\;CH_4\;band,\;the\;2.12{\mu}m\;H_2\;S(0)$ pressure-induced absorption, and the continua at $1.58{\mu}m\;and\;2.0{\mu}m$ (short K-band). All images except those with the $1.58{\mu}m$ continuum filter show bright impact sites against the relatively dark Jovian disk near the impact latitude of about $45^{\circ}$ S. This implies that dusts originated from the impacts reflect the solar radiation at high altitudes before absorbed by stratospheric $CH_4,\;NH_3 \;or\;H_2$. The impact sites observed with the $2.3{\mu}m$ filter are conspicuously bright against a very dark background. The morphology of impact sites, G, L, and H at 2.3 and $2.12{\mu}m$ filters shows clearly an asymmetric structure toward the incident direction of the comet fragments, in agreement with the studies of visible impact images obtained with the Hubble Space Telescope. Comparisons of reflectances of G, L, and H sites with simple radiative transfer models suggest that optically thick dust layers were formed at high altitudes at which methane absorption attenuates incoming sunlight only by about $1\%$. The dust layers in these sites seem to form at about the same altitude regardless of the magnitude of the impacts, but they appear to descend gradually after the impacts. The dust layers have optical depths of 2-5, according to the models.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.298-307
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• 2018

Background: Subalpine ecosystems at high altitudes and latitudes are particularly sensitive to climate change. In South Korea, the prediction of the species richness of subalpine plant species under future climate change is not well studied. Thus, this study aims to assess the potential impact of climate change on species richness of subalpine plant species (14 species) in the 17 mountain national parks (MNPs) of South Korea under climate change scenarios' representative concentration pathways (RCP) 4.5 and RCP 8.5 using maximum entropy (MaxEnt) and Migclim for the years 2050 and 2070. Results: Altogether, 723 species occurrence points of 14 species and six selected variables were used in modeling. The models developed for all species showed excellent performance (AUC > 0.89 and TSS > 0.70). The results predicted a significant loss of species richness in all MNPs. Under RCP 4.5, the range of reduction was predicted to be 15.38-94.02% by 2050 and 21.42-96.64% by 2070. Similarly, under RCP 8.5, it will decline 15.38-97.9% by 2050 and 23.07-100% by 2070. The reduction was relatively high in the MNPs located in the central regions (Songnisan and Gyeryongsan), eastern region (Juwangsan), and southern regions (Mudeungsan, Wolchulsan, Hallasan, and Jirisan) compared to the northern and northeastern regions (Odaesan, Seoraksan, Chiaksan, and Taebaeksan). Conclusions: This result indicates that the MNPs at low altitudes and latitudes have a large effect on the climate change in subalpine plant species. This study suggested that subalpine species are highly threatened due to climate change and that immediate actions are required to conserve subalpine species and to minimize the effect of climate change.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.233-240
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• 2019

High-altitude ElectroMagnetic Pulse(HEMP) is a high-power electromagnetic pulse caused by nuclear explosions at altitudes above 30 km. This pulse can cause serious damage to the electrical/electronic device. Therefore, there are a lot of studies on the effects of HEMP in the literature. When conducting studies on the effects of HEMP, it is essential to measure the simulated HEMP. Depending on the need for measurement, this paper focuses on the HEMP measurement method. This paper proposes a measurement method using frequency domain compensation to extract the correct waveform and solves the offset problem more efficiently than the conventional methods. The proposed method is verified by experiment using HEMP simulator and measurement system in ADD.

• Geomechanics and Engineering
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• v.10 no.1
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• pp.49-57
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• 2016

The high permeability-high strength concrete belongs to the typical of porous materials. It is mainly used in underground engineering for cold area, it can act the role of heat preservation, also to be the bailing and buffer layer. In order to establish a suitable model to predict the thermal conductivity and directly applied for engineering, according to the structure characteristics, the thermal conductivity predicting model was built by resistance network model of parallel three-phase medium. For the selected geometric and physical cell model, the thermal conductivity forecast model can be set up with aggregate particle size and mixture ratio directly. Comparing with the experimental data and classic model, the prediction model could reflect the mixture ratio intuitively. When the experimental and calculating data are contrasted, the value of experiment is slightly higher than predicting, and the average relative error is about 6.6%. If the material can be used in underground engineering instead by the commonly insulation material, it can achieve the basic requirements to be the heat insulation material as well.