• 한국군사과학기술학회지
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• 제12권5호
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• pp.683-688
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• 2009

A research was conducted about the Reynolds number effect on the projectile with an altitude change. The atmosphere conditions change in accordance with an altitude change. It effects the Reynolds number. To confirm how the phenomena affect the trajectory of the projectile, a computer program is designed with an altitude and a range considered. The MISSILE DATCOM which is based on the semi-empirical method was utilized to get aerodynamic coefficients. The result shows that the Reynolds number considerably changes as the altitude change. It causes to change the drag coefficient of the projectile. As the Reynolds number decreases, the skin friction drag increases significantly. It causes to decrease the maximum altitude and the range.

• 한국습지학회지
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• 제16권1호
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• pp.113-124
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• 2014

강우량은 관측소의 설치고도에 따라 관측량의 편차가 심하며, 이로 인해 도시지역과 산지지역의 강우발생 특성이 다르다. 산지효과로 인해 고도가 높아질수록 강우 관측시 불확실성이 커지는 것을 감안하면 산지지역에서의 강우관측소 밀도는 커야한다. 이러한 관측소의 고도특성이 반영된 관측망 평가는 산지효과를 반영하기 위한 것으로 산악지역에서 발생하는 돌발홍수의 효과적인 예측 및 레이더 자료의 보정에 있어 중요한 과정이 된다. 이에 본 연구에서는 강우관측소의 설치고 도를 고려한 강우관측망의 평가방법론을 제안하였다. 강우관측소의 고도별 설치밀도 파악을 위해 고정간격의 고도를 이용하는 등고도비별 설치밀도 산정방법과 유역의 면적비를 이용하는 등면적비별 설치밀도 산정방법을 적용하였다. 그 결과 등면적비를 이용하는 경우가 고도별 강우관측망의 평가에 보다 유리함을 확인하였다. 아울러 타유역과의 비교를 위해 등면적별 관측소 설치밀도의 변동계수를 이용하여 고도별 분포를 정량화 하였다. 이는 강우관측소의 설치고도분포의 균등함을 평가하는 정량적 지표가 되며, 제시된 방법론을 5대강 유역에 적용하였다. 그 결과, 설치밀도의 변동계수가 작은 유역에서는 고도별 강우설치밀도가 일정함으로 인해 보다 균등한 분포를, 반면 변동계수가 큰 유역에서는 상대적으로 고도별 설치밀도가 불균등함을 확인하였다.

• 한국항공운항학회지
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• 제20권2호
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• pp.58-63
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• 2012

An altitude chamber, also known as a hypobaric chamber, is a device used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body. Although data from altitude chamber researches using experimental animals have been accumulated, studies in the humans exposed to hypobaric conditions are seldomly reported. Despite the importance of altitude chamber flight training in the field of aviation physiology, the hematological analysis of post-flight physiological changes has rarely been performed. The aims of the present study were to investigate the alterations in blood components during altitude chamber flight and to determine whether the differences between pre- and post-flight values are significant. Sixty experienced pilots in the Republic of Korea Air Force were enrolled in the altitude chamber flight training. Venous blood samples were obtained before and immediately after the flight. Compared with the pre-flight values($6.32{\times}10^3/mm^3$, $5.02{\times}10^6/mm^3$, 15.61 g/dL, respectively), white blood cell count, red blood cell count and hemoglobin level were significantly increased after the flight($6.77{\times}10^3/mm^3$, $5.44{\times}10^6/mm^3$, 16.26 g/dL; p=0.006, p=0.012, p<0.001, respectively). These alterations may be attributable to the exposure to hypobaric hypoxia, 100% oxygen supply for denitrogenation, considerable rise and fall in altitude and psychophysical stress due to these factors. In further studies, experimental groups and methods should be individualized to ensure objectivity and diversification. In addition, multiple time-frame analyses regarding the changing pattern of each blood component are also required to elucidate the physiological process for adapting to the high terrestrial altitude exposure.

• Journal of Nutrition and Health
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• 제1권1호
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• pp.27-31
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• 1968

The author investigated the effects of dietary composition upon the work efficiency of Splague Dowley rat at high altitude, and obtained the following results: 1. At high altitude a carbohydrate-rich diets worked more favorably upon work efficiency of the animal then a protein and or fat-rich diets did. 2. It may be recommended that fibrous components be excluded from the diets. 3. Ingestion of large amounts of sugars prior to the onset of work load is highly recommended.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권1호
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• pp.67-67
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• 2007

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.476-479
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• 2008

The combustion efficiency of the solid fuel ramjet is affected by the inlet air temperature. And this inlet air temperature is dependent on the flight Mach number and the environment air temperature. If the flight altitude is changeable, the inlet air temperature and the air density also vary. The performance efficiency is investigated with this variables related to the combustion efficiency.

• 한국작물학회지
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• 제51권2호
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• pp.130-136
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• 2006

Growth and quality of rice are affected by various factors including the location of cultivation. This study was conducted to investigate the effects of altitudinal locations on the growth and yield-related components of rice. Nineteen Japonica type varieties were grown at Iksan (altitude, 10 m), Imsil (altitude, 150 m), Jinan (altitude, 275 m) and Jangsu (altitude, 430 m) at a similar latitude in Jeonbuk province in the south western Korea. Minimum air temperature showed a strong negative correlation with altitude. The morphological traits and yield-and quality-related components were analyzed. Longer days to heading was required at higher altitudes. However, culm length, panicle length, panicle number, grain number and rice yield were reduced at higher altitudes. Protein content of brown rice increased but fatty acid content decreased at higher altitudes. Amylose content was affected by neither the altitude nor the ecotype. Palatability of polished rice tends to be improved at higher altitudes and in early-maturing ecotypes but its relationships with altitude and ecotype were not significant. Head rice ratio was lower at higher altitudes but broken rice ratio vise versa. These results indicate that growth and quality of rice are affected significantly by changes in temperatures at the locations of different altitude. Also, the characters related to yield and quality of rice often respond incompatibly to the changes in altitudes. These results could provide valuable information for the strategic planning of rice production in geographically diverse areas.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.228-233
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• 2014

Reduction of the atmospheric pressure in high altitude affects brake booster system which was operated by the difference between the intake pressure and the atmospheric pressure. So, braking system can not stably perform due to decrease of brake boost pressure. In this study, effects of altitude change on engine intake pressure was analyzed by prediction model of engine intake pressure which was studied previously. And engine intake pressure was simulated by simulation model in various driving conditions and environmental conditions.

• 한국전산유체공학회지
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• 제9권3호
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• pp.18-25
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• 2004

Multi plume effects on the base heating have been Investigated with a CFD program. As the flight altitude increases, the plume expansion angle increases regardless of the single or clustered engine. The plume interaction of the clustered engine makes a high temperature thermal shear in the center of four plumes. At low altitude, the high temperature shear flow stays in the center of plumes, but it increases up to engine base with the increasing altitude. At high altitude, the flow from plume to base and the flow from base into outer free stream are supersonic, which transfers the high heat in the center of plumes to the base region. The radiative heat of the clustered engine varies from 220 kW/m² to 469 kW/m² with increasing altitude while those of the single engine are 10 kW/m² and 43.7 kW/m². And the base temperature of the clustered engine varies from 985K to 1223K, and those of the single engine are 483K and 726K. This big radiative heat of clustered engine can be explained by the active high temperature base flow and strong plume interactions.

• 한국항공운항학회지
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• 제14권3호
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• pp.1-6
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• 2006

The altitude engine test is a sort of engine performance tests carried out to measure the performance of a engine at the simulated altitude and flight speed environments prior to that at the flight test. During the performance test of a engine, various values such as pressures and temperatures at different positions, air flow rate, fuel flow rate, and the load by thrust are measured. These measured values are used to derive the representative performance values such as the net thrust and the specific fuel consumption through a momentum equation. Hence each of the measured values has certain effects on the total uncertainty of the performance values. In this paper, the combined standard uncertainties of the performance variables at the engine test were estimated by the uncertainty analysis of the measurement values and the repeatability and reproducibility of the altitude test measurement were assessed by the analysis of variation on the repeated test data with different operator groups.