• Journal of the Speleological Society of Korea
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• v.8 no.9
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• pp.6-14
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• 1983

성유굴도 다른 석회동굴과 같이 지면에 투수된 지하수에 의하여 그 지반을 덮고 있는 석회암층이 용해, 용식되면서 지면하에 용출이 생겼다. 물론 지하수대가 순환수대인 경우도 있고 한편 포화수대상태에 있는 경우의 두 가지가 있는데 성유굴은 포화수대의 지하수면하에서 형성된 것이다. 그리고 그후에 순환수류의 영향을 받게 되었다. (중략)

• Journal of the Speleological Society of Korea
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• v.9 no.10
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• pp.57-65
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• 1984

성유굴도 다른 석회동굴과 같이 지면에 투수된 지하수에 의하여 그 지반을 덮고 있는 석회암층이 용해, 용식되면서 지면하에 동굴이 생겼다. 물론 지하수대가 순환수대인 경우도 있고 한편 포화수대상태에 있는 경우의 두가지가 있는데 성유굴은 포화수대의 지하수면하에서 형성된 것이다. 그리고 그후에 순환수류의 영향을 받게 되었다. (중략)

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.1-16
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• 2002

The purposes of this study were to investigate the effects of strength training on the change of ground reaction force for the children with trisomy 21 Down syndrome. The subjects of this study were consisted of eight elementary school students with Down syndrome who participated in the strength training. The strength training was administered by six items such as squat, leg curl, leg extension, toe raise, sit-ups, and hyperextension. For strengthening muscle, each group also was treated by walking for 8 weeks, three times a week, 10-15RM, 3sets, which was based on the principle of progressive overload. For inquiring the effect of strength training, the ground reaction force variables were measured in two phases : before-training and 8 week-after training. The gait of each subject was acquisition using 2 AMTI force platforms set at 100 frequency. The results of this study were as follows: The pattern of vertical, antero-posterior and medio-lateral forces, trajectory of net COP and the timing ratio of reaching the each events were shown variously. So, it is not easy to explain these variables clearly. As the result of strength training, these variables were changed. However, the results of within subjects differ greatly, there was no difference statistically.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.373-384
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• 2013

This paper is the second paper among two papers which constitute the paper about the rigid body dynamic analysis on the spent nuclear fuel disposal canister under accidental drop and impact to the ground. This paper performed the numerical study on the rigid body dynamic analysis. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground and required for the structural safety design of the canister is computed numerically. The main content of this numerical study is about the technical method how to compute the impulsive forces occurring in the canister under accidental drop and impact to the ground by using the commercial rigid body dynamic analysis computer codes. On the basis of this study the impulsive force which is occurring in the canister in the case of collision with the ground is numerically computed. This numerically computed impulsive force is increasing as the canister weight is increasing, and the canister falls plumb down and collides with the ground in three types according to the analysis results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.28-31
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• 2018

This paper investigates the ground reflection effect on the channel capacity of an orbital angular momentum (OAM) multi-mode transmission system that uses uniform circular array (UCA) antennas. The ground-reflected signals cause inter-mode interferences between the OAM modes, and lead to system performance degradation. The OAM multi-mode channel capacity severely degrades owing to the ground reflection as the transmission distance increases. Increasing the UCA height above the ground and using highly directive array elements can mitigate the ground reflection effect and increase the channel capacity.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.489-496
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• 2010

In this paper, a self-organization framework for swarm systems in three dimensions is presented. The framework uses artificial potential functions(APFs) to direct the robots toward the goal as well as to keep them in a swarm system. This research extends conventional APFs used for self-organizations in two dimension environment to three dimensions. In three dimension environment, the ground potential for the boundary surfaces that commonly appear in three dimension environments is proposed. Accordingly, the comparison between the paths without and with the ground potentials shows the necessity and effect of ground potentials. Extensive simulations are given to show the effectiveness of the extended potentials and various properties in three dimension environments.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.173-173
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• 2017

지구표면에서 발생하는 물순환, 에너지순환, 탄소순환은 토지-대기-식생간의 물리화학적 관계에 의하여 발생하며 이를 모사하기 위해 지면 및 기후모델이 활용된다. 본 연구에서는 NCAR의 지면모형인 Community Land Model(CLM) v4.5를 동아시아에 적용하고자 한다. 동아시아 범위에서 Fluxtower가 설치되어 물, 에너지, 탄소 플럭스 자료가 관측된 지점에서 모형을 구동하고 결과를 평가하였다. CLM 결과에 따른 증발산(Evapotranspiration), 잠열(Latent heat), 헌혈(Sensible heat)과 같은 물 및 에너지 순환에 관한 결과 뿐 아니라 총 일차생산량(Gross primary production), 순생태계순환(Net ecosystem exchange), 생태계 호흡량(Ecosystem respiration)과 같은 탄소순환에 관한 결과를 비교, 분석하였다. 특히, 기초 결과 분석에 따라 지면 모형 내의 여러 모듈 중에서 화재 관련 모듈에 초점을 맞추어 CLM 모형을 개선하였다. 화재는 식생의 성장에 많은 영향을 미치는 모듈로서 탄소순환 모의에 중요한 역할을 한다. 전 지구 대상 모의를 기반으로 하는 CLM에서 삼림 및 초지 지역의 화재 발생는 국내총생산(Gross domestic product, GDP) 및 인구밀도에 따라 모수화되어 있으나, 이는 전 지구 혹은 지역 대상이 아닌 지점 수준의 모형적용을 위해 부적합하다. 이에 관련 모수들을 재산정하고 개선된 모형 결과를 정량화하기 위해 위에서 언급한 물순환, 에너지순환, 탄소순환 관련된 변수들의 모의값을 Fluxtower 관측값과 비교, 분석하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.191-191
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• 2023

기후변화 대응을 위한 탄소 중립의 중요성이 대두되는 요즘, 생태계의 가장 큰 메탄 저장소로서 지구의 탄소 순환에 주요한 영향을 미치는 습지에 대한 이해는 필수적이다. 전지구 지면 모델인 Community Land Model(CLM)에 Functionally Assembled Terrestial Ecosystem Simulator(FATES) 외부 모듈을 함께 구동한 지면 생태계 모델 CLM-FATES는 지면 heterogeneity와 다양한 식생 종류를 고려하여 에너지 플럭스, 토양 수문, 생화학적 과정 등을 모의함으로써 탄소 동태 변화를 포함한 장기적 생태계 동태 변화 모의를 가능하게 한다. 본 연구는 CLM-FATES 모델을 미국 캘리포니아주 Mayberry Wetland (US-Myb)와 Twitchell East End Wetland (US-Tw4)에 적용하였다. 모델의 대기 입력 자료로는 FLUXNET-CH4에서 제공하는 에디 공분산 기반 플럭스 관측 자료를 사용하였다. 기존 CLM-FATES 모델은 토양이 장기간 포화 혹은 침수되어 지표 위 혹은 지표면 가까이 발달한 지하수면을 가지고 있는 습지의 수문학적 특성을 잘 반영하지 못해 정밀한 습지 생태계 동태 변화 모의에 한계를 가지고 있다. 본 연구에서는 CLM-FATES를 통한 보다 정확한 습지 생태계 모의를 위해 모델 내 토양 수문 관련 모듈을 수정하여 모델이 습지의 수문학적 특성을 반영할 수 있도록 하였다. 모델 구동 결과 도출한 잠열, 총일차생산량(Gross Primary Production: GPP)과 순생태계생산량(Net Ecosystem Production, NEP) 플럭스, 메탄 플럭스, 엽면적지수(Leaf Area Index; LAI)와 지표수 높이에 대해 관측값 대비 RMSE 및 R² 값을 계산하여 모의 결과의 적절성을 분석하였다. 이러한 모델 개선 경험을 바탕으로 추후 우리나라 습지 사이트에 모델을 적용하여 습지 탄소 동태 예측에 활용할 계획이다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.359-365
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• 2011

This study aims at filtering ALS points into ground and non-ground effectively through labeling and window based algorithm by utilizing 2D adjacency based on scan line. Firstly, points adjacency is constructed through minimal search based on scan line. Connected component labeling algorithm is applied to classify raw ALS points into ground and non-ground by utilizing the adjacency structure. Then, some small objects are removed by morphology filtering, and isolated ground points are restored by IDW estimation. The experimental results shows that the method provides good filtering performance( about 97% accuracy) for diverse sites, and the overall processing takes less time than converting raw data into TIN or raster grid.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.261-272
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• 2005

3D models in urban areas are essential for a variety of applications, such as virtual visualization, GIS, and mobile communications. LIDAR (Light Detection and Ranging) is a relatively new technology for obtaining Digital Terrain Models (DTM) of the earth's surface since manual 3D data reconstruction is very costly and time consuming. In this paper an approach to extract ground and non-ground points data from LIDAR data by using filtering is presented and the accuracy for generating DTM from ground points data is evaluated. Numerous filter algorithms have been developed to date. To determine the performance of filtering, we selected three filters which are based on the concepts for height difference, slope, and morphology, and also were applied two different data acquired from high raised apartments areas and low house areas. From the results it has been found that the accuracy for generating DTM from LIDAR data are 0.16 m and 0.59 m in high raised apartments areas and low house areas respectively. We expect that LIDAR data is used to generate the accurate DTM in urban areas.