• 산업공학
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• 제17권spc호
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• pp.62-68
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• 2004

HAPS (High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is a promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios.

• 위성통신과 우주산업
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• 제13권1호통권28호
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• pp.118-124
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• 2006

HAPS(High Altitude Platform Station) which is defined as a station located on an object at an altitude of 20 to 50 km and at a specified, nominal, fixed point relative to the earth is promising technology capable of providing broadband multimedia services. In this study, economical aspects of HAPS service are analyzed by estimating the revenue and costs incurred by the service. To evaluate the profitability of HAPS service, the number of subscribers is estimated and then the net present value (NPV), payback period, and the rate of return on investment (ROI) are calculated under various scenarios

• Animal Systematics, Evolution and Diversity
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• 제30권1호
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• pp.33-38
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• 2014

Caeneressa diaphana muirheadi (Felder) and Caeneressa brithyris (Druce) have been recorded for the first time from India. Further, a new combination viz. Caeneressa melaena (Walker) comb. nov., has also been proposed on the basis of external genitalic features. With these records, genus Caeneressa will be represented by five species from India, Caeneressa diaphana (Kollar), Caeneressa diaphana muirheadi (Felder), Caeneressa brithyris (Druce), Caeneressa melaena (Hampson) and Caeneressa swinhoei (Leech). The studied material was collected from North-Eastern states of India. Caeneressa brithyris (Druce) was collected near riverside at low altitude whereas the other two species were collected at high altitude.

• 한국환경과학회지
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• 제21권6호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.219-222
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• 2007

본 연구에서는 노즐 외기 압력 변화에 따른 KSLV-I 2단 고체추진기관의 성능 분석을 수행하였다. 2단 고체추진기관은 고도 약 300km 상공에서 연소를 할 예정이다. 모터의 성능 검증을 위해 대기 압력 환경에서 연소시험을 수행하였다. 그리고, 환경 시험 설비를 적용하여 진공환경의 모터 성능 검증을 진행하였다. 지상 및 진공환경에서의 모터 비추력 변화를 통해 노즐 외기 압력이 고체추진기관의 성능에 미치는 영향을 분석하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.65-70
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• 1999

Radiative heating of a liquid rocket base plane due to plume emission is numerically investigated. Calculation of flow and temperature fields around rocket nozzle precedes and thereby realistic plume shape and temperature distribution inside the plume are obtained. Based on the calculated temperature field, radiative transfer equation is solved by discrete ordinate method. The averaged radiative heat flux reaching the base plane is about $5kW/m^2$ at the flight altitude of 10.9km. This value is small compared with radiative heat flux caused by constant-temperature (1500K) plume emission, but it is not negligibly small. At higher altitude (29.8km), view factor between the babe plane and the exhaust plume is increased due to the increased expansion angle of the plume. Nevertheless, the radiative heating disappears since the base plane is heated to high temperature (above 1000K) due to convective heat transfer.

• The Korean Journal of Ecology
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• 제21권1호
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• pp.105-112
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• 1998

Characteristics of species distribution in the Baekdoo Great Mountain Chain of Kangwon Province were discussed. Resulting from Detrending Correspondence Analysis based on the floristic composition of 48 mountains, the mountains of the Baekdoo chain tended to aggregate on DCA axis. it represented that there was the peculiar floristic composition of the Baekdoo chain separated from the other mountains. High altitude, longitude near the East Sea and large number of vascular species were main factors for the distribution pattern. And exponential relationships between endemic rare species and number of species were clarified. Even though the regions of the Baekdoo Great Mountain Chain had been conserved relatively well, many regions have been faced to be disturbed for tourism, agriculture, forestry, livestock industry and mining since the local autonomy. Thusm, the necessity for the establishment of large area network through the connection of scattered protected areas in the Baekdoo Great Mountain Chain was suggested. it would play a role as a core of nature conservation to sustain species diversity in Korea.

• KIEAE Journal
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• 제14권5호
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• pp.67-73
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• 2014

This study aims at examining kinetic efficient shading systems and their implementation methods. These days, the importance of the shading devices are getting more significant due to the energy problem. Cordially, suitable shade designs are required as an important element for the exterior envelope of the building. This study employs the optimal shading design as an efficient shading method with the kinetic system that can be converted actively by the altitude of the sun. The proposed kinetic shading system works not only as a lightshelf in case the altitude of the sun is high but also as a vertical louver when the sun is getting lower in order to block the direct sunlight. This study has analyzed the thermal performance and shading coefficient of the kinetic shading system in comparison to existing fixed shading devices using the Ecotect. The results, in sum, conclude that the suggested kinetic shading system could decrease direct sunlights 26.2% more than the existing shading methods.

• International Journal of Advanced Culture Technology
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• 제7권4호
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• pp.327-333
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• 2019

Wind speed data constitute important weather information for aircrafts flying at low altitudes, such as drones. Currently, the accuracy of low altitude wind predictions is much lower than that of high-altitude wind predictions. Deep neural networks are proposed in this study as a method to improve wind speed forecast information. Deep neural networks mimic the learning process of the interactions among neurons in the brain, and it is used in various fields, such as recognition of image, sound, and texts, image and natural language processing, and pattern recognition in time-series. In this study, the deep neural network model is constructed using the wind prediction values generated by the numerical model as an input to improve the wind speed forecasts. Using the ground wind speed forecast data collected at the Boseong Meteorological Observation Tower, wind speed forecast values obtained by the numerical model are compared with those obtained by the model proposed in this study for the verification of the validity and compatibility of the proposed model.

• 한국환경과학회지
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• 제23권4호
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• pp.615-623
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• 2014

The groundwater level varies according to the characteristics and composite materials of aquifer. In this study, specific yield and reaction factor which are the major two hydrogeological parameters in the WTF(Water Table Fluctuation) method were estimated and analyzed spatial characteristics. 8 groundwater level stations which have enough measuring period and high correlation with rainfall in the Hancheon watershed were used. The results showed that specific yield was randomly distributed and reaction factor showed inverse trend with altitude. If the enough data were collected, reaction factor according to altitude in ungauged points could be estimated by using these parameter characteristics.