• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.89-94
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• 2006

DGPS provides less altitude accuracy than horizontal accuracy according to geometric characteristics of GPS satellite arrangement. To assist DGPS altitude measurements, two barometric altitude sensors were used and set up at the mobile and the reference station respectively to get the differential altitude. This differential altitude is coupled with the DGPS altitude measurement by a Kalman filter so that the improved altitude is estimated. The differential altitude is based on the relative altitude measurement but results in providing the absolute altitude. The precision of this differential altitude is verified by experiments in accordance with a baseline length.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.629-639
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• 2016

Batch process TRN(Terrain Relative Navigation) using an altimeter is a technique to correct position by correlating a series of periodically measured terrain height profile and terrain height candidate profile of the DEM(Digital Elevation Map). However, it is generally known that the performance of TRN is degraded when measured terrain height profile and terrain height candidate profiles of the DEM are similar at hill or repetitive terrain. In this paper, area based terrain slope roughness index[11] is applied and area based terrain curvature roughness index which can detect similarity of terrain in ROI(Region Of Interest) is proposed to overcome this problem. Applying terrain roughness indexes to terrain relative navigation system of lunar lander, it is shown that TRN using area based terrain roughness results in improved performance compared to conventional trajectory based method through simulation.

• Korean Journal of Environment and Ecology
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• v.32 no.4
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• pp.413-424
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• 2018

The study analyzed the effects of topographic structures and altitude in mountainous parks in Mt. Namsan in Gyeongju on the generation of anions. The temperature was at ridge ($9.82^{\circ}C$) > valley ($8.44^{\circ}C$), the relative humidity valley (59.01 %) > ridge (58.64 %), the solar radiation ridge ($34.40W/m^2$) > valley($14.69W/m^2$), the wind speed ridge (0.63m/s) > valley(0.37m/s), and the negative ion valley($636.81ea/cm^3$) > ridge($580.04ea/cm^3$). In the valley, the correlation with altitude was verified for the temperature, relative humidity, solar radiation, and negative ion generation in the valley. The relative humidity, solar radiation, and negative ion indicated a positive correlation while the temperature had a negative correlation. In the ridge, the correlation with altitude was verified for the temperature, relative humidity, wind speed, solar radiation, and negative ion generation. The relative humidity, solar radiation, and negative ion generation indicated a positive correlation while the temperature and wind speed had a negative correlation. The regression analysis showed the prediction equation of y=-0.006x+9.663 (x=altitude, y=temperature) in the valley and y=-0.009x+11.595 (x=altitude, y=temperature) in the ridge for the temperature, y=0.027x+53.561 (x=altitude, y=relative humidity) in the valley and y=0.008x+56.646 (x=altitude, y=relative humidity) in the ridges for the relative humidity, and y=0.027x+53.561 (x=altitude, y=negative Ion generation) in the valley and y= 0.008x+56.646 (x=altitude, y=negative Ion generation) in the ridge for the negative ion generation.

• Proceedings of the Korea Water Resources Association Conference
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• 1980.08a
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• pp.51-52
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• 1980

하천형태학적 특성은 유역의 수문학적 특성 및 수리학적 특성과 밀접한 관계를 가진다. 본 논문은 하천형태학적 특성과 빈도유량 및 하도의 수리기하학적 특성간의 상관성을 금강수계를 대상으로 분석하였으며 이들 연구의 목적은 미계측지점에 대한 이수계획을 수립하는데 필요한 자료를 제공하는데 있다. 금강수계의 하천형태학적 특성분석은 Horton의 하천차수개념을 이용하여 하천지형의 3대 법칙에 의하여 분석하였으며 분석결과는 Horton의 법칙과 잘 일치하였다. 또한 유역특성과 수로특성간의 상관분석인 하천연장-유역면적관계와 상대고도-상대고도관계분석에서도 밀접한 상관성을 보여 주었다. 금강수계내의 5개수위표 지점에서 생기빈도 0.1~0.9의 유량자료를 사용하여 얻는 각 지점의 유량빈도곡선은 대체로 지수함수관계로 표시할 수 있었다. 하천형태학적 특성을 연속적으로 표시하기 위하여 비례하천차수를 도입하였으며 이를 이용하여 유량 = 생기빈도 - 비례하천차수간의 관계에 대한 수학적 모형을 정립하였다. 또한 서로 다른 두 축척에 따라 하천차수는 달라지나 하천형태학적 특성에 관한 Horton의 3대법칙에는 근본적으로 영향이 없음을 알 수 있었다. 유역의 하천형태학적 특성을 매개변수로 하여 빈도유량과 수리기하학적 인자간의 관계, 유역면적과 수리기하학적 인자간의 관계 및 연평균 유출용적과 수리기하학적 인자간의 관계를 분석하여 각각에 대한 수학적 모형을 제안하였다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.307-308
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• 1999

오존전량은 대류권계면 고도[Hoinka at al., 19961, 기온과 지위 고도[Spankuch and Schulz, 1995], 잠재 와도[Vaughan and Price, 1991] 또는 상대 와도와 같은 기상 변수와 높은 상관관계를 나타낸다. 그리고 성층권 오존량의 감소는 지표 유해자외선을 증가시킨다는 연구 결과가 발표되고 있다(예: 조회구 등 1998; Zerefos et al. 1997).(중략)

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.314-319
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• 2019

In this study, we propose a W-band frequency modulated continuous wave(FMCW) radar altimeter that can measure the altitude based on the frequency differences of transmitted and received signals. This W-band FMCW system is powered by an altitude control algorithm, which we propose to help prevent collisions of drones with obstacles in real deployment by measuring the relative altitude. It is shown that this algorithm enables the drone to be positioned within a 3 % error of altitude from the desired input height. The chip used in the W-band transmitter and receiver was fabricated using a 65-nm CMOS process, and a horn antenna was directly fed by incorporating an embedded waveguide feeder into the chip. The clutter spectra observed in terrains including soil, grass, and calm lake water were measured and compared, confirming the reflectivity characteristics of various surfaces of different water contents.

• Korean Journal of Environment and Ecology
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• v.14 no.1
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• pp.80-87
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• 2000

구상나무림 보전관리의 기초자료를 마련하고자 지리산 한라산 및 덕유산의 아고산지대에 95개의 조사구를 설치하여 한국특산종 구상나무의 생육현황과 구상나무 서식지의 입지인지를 조사하였다 구상나무는 흉고직경 10-30cm의 범위에 드는 나무들이 주로 고사목으로 나타났으며 고사목의 비율은 전체적으로 총개체수의 11.51%였다 고사목의 비율또한 덕유산에서 18.18%로 가장높게나타났고 한라산 지역이 8.11%로 가장 낮게 나타났다 조사구당 구상나무 개체수 치수의 개체수 구상나무의 수고와 흉고직경 생육현황표에 의한 점수 구상나무의 상대밀도 등은 지역간에 통계적 유의차가 인정되었다 생육중인 구상나무의 활력은 한라산 지리산, 덕유산으로 순으로 좋았다 조사구당 구상나무 치수의 개체수는 한라산에서 6.00개체로 가장 많았으며 덕유산에서는 치수가 없는 것으로 나타났다 구상나무의 상대밀도도 한라산, 지리산, 덕유산 순으로 높게 나타났다. 조사구당 구상나무 개체수는 해발고와 정의 상관, 방위, 낙엽퇴의 두께, 조사구당 교목의 개체수 및 종수, 활엽수 상대밀도와는 부의 상관이 인정되었다. 구상나무 상대밀도는 해발고와는 고도의 정의 상관관계 방위 조사 구당교목의 개체수 및 종수 수관울폐도, 활엽수 상대밀도와는 부의 상관관계가 인정되었다 지리산, 한라산 및 덕유산에 자생하는 구상나무는 해발고가 높으며 볕이 잘들고 낙엽퇴가 얕으며 종구성이 단순하고 활엽수가 적은 지역에 보다 많이 분포한다.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.292-295
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• 2007

개발계획이나 환경계획 수립시에 절대적인 해발고도를 기준으로 지형적 특성을 분석한다면 절대표고가 낮은 지역은 대부분 개발가능지로 구분된다. 따라서 지역적 특성을 반영하는 상대표고를 적용하여야 하나 산의 경계구획，능선설정 등의 어려움으로 아직 전국단위의 구체적인 연구는 미흡한 실정이다. 이에 본 연구에서는 최근 Weiss 가 제안한 지형위치지수 ( Topogr aph i c Position Index, TPI) 를 적용하여 전국 단위의 상대표고 분석 가능성을 검토하였다. TPI 모델 도출 결과와 기존 환경부 국토환경성 평가에 사용한 Gaia EZeye 모델 결과를 중첩 비교한 결과 정확도가 높은 것으로 나타났다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.4
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• pp.299-311
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• 2020

This paper analyzes the distribution of water vapor pressure and relative humidity in complex terrains by collecting weather observation data at 6 locations in the valley in Jungdae-ri, Ganjeon-myeon, Gurye-gun, Jeolla South Province and 14 locations in Akyang-myeon, Hadong-gun, Gyeongsang South Province, which form a single drainage basin in rural and mountainous regions. Previously estimated water vapor pressure used in the early warning system for agrometeorological hazard and actual water vapor pressure arrived at using the temperature and humidity that were measured at the highest density (1.5 m above ground) at every hour in the valley of Jungdae-ri between 19 December 2014 and 23 November 2015 and in the valley of Akyang between 15 August 2012 and 18 August 2013 were compared. The altitude-specific gradient of the observed water vapor pressure varied with different hours of the day and the difference in water vapor pressure between high and low altitudes increased in the night. The hourly variations in the water vapor pressure in the weather stations of the valley of Akyang with various topographic and ground conditions were caused by factors other than altitude. From the observed data of the study area, a coefficient that adj usts the variation in the water vapor pressure according to the specific difference in altitude and estimates it closer to the actual measured level was derived. Relative humidity was simulated as water vapor pressure estimated against the saturated water vapor pressure, thus, confirming that errors were further reduced using the derived coefficient than with the previous method that was used in the early warning system.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.44-54
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• 2001

This study was conducted to estimate microclimate of natural deciduous forest in national forest of Pyungchang, Kangwon province and to investigate the effects of the microclimatic conditions on the periodic annual increment of diameter by site types. In this study, site was first classified by nine types considering both elevation (higher than 1,000 m, 700∼1,000 m, and lower than 700 m) and topographical conditions (ridge, slope and valley). For each of site types, diameter growth was measured by using increment borer and periodic annual increment of diameter was then analyzed. A topoclimatological technique, for estimating microclimatic conditions, which make use of empirical relationships between the topographical factor and the climatic normals in the study area was applied to produce monthly mean, maximum and minimum temperatures, relative humidity, precipitation and hours of sunshine. From these monthly estimtes, 17 weather variables such as warmth index, coldness index, index of aridity etc. which affect the diameter growth were computed for each of site types. The periodic annual increment of diameter was then correlated with and regressed on the 17 weather variables to examine effects of microclimatic conditions on the diameter growth by site types. From the correlation analysis, it was found that the diameter growth by site types was positively correlated with all of 17 weather variables except the warmth index. Especially, the conditions such as high relative humidity and large amount of sunshine hours provide favorable environment for the growth of diameter. On the other hand, it was also found that diameter growth was negatively iufluenced by warmth index. According to the regression analysis, the periodic annual increment of diameter could be well predicted by index of aridity and mean relative humidity for the growing season.