• The Journal of Engineering Geology
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• v.25 no.1
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• pp.83-91
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• 2015

Few studies have investigated soil management policy and soil erosion measurement, whereas the occurrence of climate change requires the establishment of robust soil management systems and appropriate control of soil erosion. In this study, we developed a smart sensor for real-time quantitative measurements of soil erosion at the watershed scale. The smart sensor consists of an ultrasonic sensor, a rainfall meter, a solar cell, an RTU (remote terminal unit),and a CDMA (code division multiple access) and it was programmed to take a measurement every 30 minutes. The depths measured by the smart sensor were compared with data from terrestrial LiDAR. Experimental results showed a strong correlation in the depth of soil erosion between LiDAR and the ultrasonic sensor for the period from 22 August to 11 October 2013. Furthermore, the correlation coefficient between soil erosion depth (mm) and soil erosion volume (m³) was 0.9063 in the lower region of the watershed and is 0.9868 in the upper region. The proposed ultrasonic sensor technique can provide high-quality data for soil conservation and management systems in the future.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.931-939
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• 2022

In Korea, about two-thirds of the precipitation is concentrated in the summer season, so the problem of turbidity in the summer flood season varies from year to year. Concentrated rainfall due to abnormal rainfall and extreme weather is on the rise. The inflow of turbidity caused a sudden increase in turbidity in the water, causing a problem of turbidity in the dam reservoir. In particular, in Korea, where rivers and dam reservoirs are used for most of the annual average water consumption, if turbidity problems are prolonged, social and environmental problems such as agriculture, industry, and aquatic ecosystems in downstream areas will occur. In order to cope with such turbidity prediction, research on turbidity modeling is being actively conducted. Flow rate, water temperature, and SS data are required to model turbid water. To this end, the national measurement network measures turbidity by measuring SS in rivers and dam reservoirs, but there is a limitation in that the data resolution is low due to insufficient facilities. However, there is an unmeasured period depending on each dam and weather conditions. As a sensor for measuring turbidity, there are Optical Backscatter Sensor (OBS) and YSI, and a sensor for measuring SS uses equipment such as Laser In-Situ Scattering and Transmissometry (LISST). However, in the case of such a high-tech sensor, there is a limit due to the stability of the equipment. Therefore, there is an unmeasured period through analysis based on the acquired flow rate, water temperature, SS, and turbidity data, so it is necessary to develop a relational expression to calculate the SS used for the input data. In this study, the AEM3D model used in the Water Resources Corporation SURIAN system was used to improve the accuracy of prediction of turbidity through the turbidity-SS relationship developed based on the measurement data near the dam outlet.

• Korean Journal of Remote Sensing
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• v.37 no.6_2
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• pp.1859-1867
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• 2021

This study investigated seasonal characteristics of the particulate matter (PM) in the atmosphere and rainwater quality in Busan, South Korea, and evaluated the seasonal effect of PM₁₀ concentration in the atmosphere on the rainwater quality using multivariate statistical analysis. The concentration of PM in the atmosphere and meteorological observations(daily precipitation amount and rainfall intensity) are obtained from automatic weather systems (AWS) by the Korea Meteorological Administration (KMA) from March 2020 to August 2020. Rainwater samples (n = 216, 13 rain events) were continuously collected from the beginning of the precipitation using the rainwater collecting device at Pukyong National University. The samples were analyzed for pH, EC (electrical conductivity), water-soluble cations(Na⁺, Mg²⁺, K⁺, Ca²⁺, and NH₄⁺), and anions(Cl^-, NO₃^-, and SO₄^2-). The concentration of PM₁₀ in the atmosphere was steadily measured before and after the precipitation with a custom-built PM sensor node. The measured data were analyzed using principal component analysis (PCA) and Pearson correlation analysis to identify relationships between the concentration of PM₁₀ in the atmosphere and rainwater quality. In spring, the daily average concentration of PM₁₀ (34.11 ㎍/m³) and PM_2.5 (19.23 ㎍/m³) in the atmosphere were relatively high, while the value of daily precipitation amount and rainfall intensity were relatively low. In addition, the concentration of PM₁₀ in the atmosphere showed a significant positive correlation with the concentration of water-soluble ions (r = 0.99) and EC (r = 0.95) and a negative correlation with the pH (r = -0.84) of rainwater samples. In summer, the daily average concentration of PM₁₀ (27.79 ㎍/m³) and PM_2.5 (17.41 ㎍/m³) in the atmosphere were relatively low, and the maximum rainfall intensity was 81.6 mm/h, recording a large amount of rain for a long time. The results indicated that there was no statistically significant correlation between the concentration of PM₁₀ in the atmosphere and rainwater quality in summer.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.127-136
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• 2008

Geophysical survey for establishing a wide site for the distribution of water content, wetting front infiltration due to the rainfall, and distribution of groundwater level has been performed by using 8round penetration radar (GPR) method, electrical resistivity method, and so on. On the other hand, a narrow area survey was performed to use a permittivity method such as time domain reflectometry, frequency domain reflectometry, and amplitude domain reflectometry methods for estimating volumetric water content, soil density, and concentration of contaminant in surface and subsurface. The permittivity methods establish more corrective physical parameters than different found survey technologies mentioned above. In this study for establishment of infiltration behaviors for wetting front in the unsaturated soil caused by an artificial rainfall, soil physical parameters for volumetric water content, pore water pressure, and pore air pressure were measured by FDR measurement device and pore water pressure meter which are installed in the unsaturated weathered granite soil with different depths. Consequently, the authors were proposed to a new establishment method for analyzing the variations of volumetric water content and wetting front infiltration from the responses of infiltrating pore water in the unsaturated soil.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.208-215
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• 2019

The goal of this study was to analyze the reactivity of a volumetric water content sensor (soil moisture sensor) and tensiometer and to review their use in the early detection of a shallow landslide. We attempted to demonstrate shallow and rapid slope collapses using three different soil ratios under artificial rainfall at 120 mm/h. Our results showed that the measured value of the volumetric water-content sensor converged to 30~37%, and that of the tensiometer reached -3~-5 kPa immediately before the collapse of the soil under all three conditions. Based on these results, we discussed a temporal range for early warnings of landslides using measurements of the volumetric water content sensors installed at the bottom of the soil slope, but could not generalize and clarify the exact timing for these early warnings. Further experiments under various conditions are needed to determine how to use both sensors for the early detection of shallow landslides.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.130-132
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• 2004

프로세서, 센서 등의 소형화와 저가격화는 어느 곳에서나 유무선 네트웍과 연결되는 편재형 디바이스들의 출연을 가능하게 했다. 이러한 디바이스들은 점점 많은 기능을 가지고 인텔리전트한 기능을 제공하고 있다. 그러나 기존의 상용 RTOS는 특정 제품에의 의존도가 높고, 멀티미디어 응용과 같은 새로운 편재환경에의 요구 사항을 지원하고 있지 않으므로 이러한 환경변화에 적응하는 것이 어렵다. 따라서 소형의 휴대 정보 단말에서부터 홈 서버에 이르기까지 다양한 종류의 편재형 기기에 사용될 수 있는 확장성과 풍부한 기능을 갖춘 표준 실시간 OS의 개발이 필요하다. Qplus-P는 이와 같은 편재형 컴퓨팅을 지원하기 위한 실시간 소프트웨어 플랫폼이다. 이에는 실시간 운영체제 커널, 라이브러리 및 응용, 사용자 개발 도구가 포함된다. 특히 커널은 확장 가능한 구조를 채택하여 다양한 내장형 기기에 적용 가능한 이식성을 지원하며, 사용자 개발 도구는 특정 내장형 기기에서의 OS의 이식을 지원하는 개발 도구로 편리한 사용자 인터페이스를 제공한다.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.224-227
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• 2007

마이크로파 센서 자료를 이용하여 태풍 강도를 산출하고자 TRMM TMI로부터 관측된 자료와 태풍 강도의 최대 상관성을 나타내는 지역올 찾고 최적의 상관 변수를 선정하였다. 분석기간은 2004년 6월부터 9월까지 발생된 태풍으로써 18개의 사례이다. TMI로부터 관측된 85 GHz 채널의 밝기온도，구름내 총 수증기량，얼음양，강우 강도，잠열방출양이 태풍 강도와의 상관성 분석을 위한 변수로 분석되었다. 태풍의 강도는 RSMC-Tokyo에서 발표된 Best track의 최대 풍속 자료를 이용하였다. 위성 관측 변수를 태풍 중심으로부터 공간 평균하였을 때 반경 2.0-2.5도 정도의 평균거리에서 최대의 상관성을 보였다. 위성 자료로부터 태풍 중심 풍속을 추정하기 위하여 회귀분석을 하였다. Best track과의 오차는 85 GHz 밝기온도와 수증기량을 이용한 다중 회귀 분석에서 오차가 최소를 보였다. 한편， 태풍강도 예측을 위한 통계모델에 마이크로파 위성 자료를 예측인자로 입력하여 태풍강도의 정확도가 3-6%정도 향상됨을 보였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.1-3
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• 2015

본 논문에서는 하둡 환경상에서 개발 중인 공간 빅데이터 저장 관리 시스템의 구조를 설명한다. 본 시스템은 공간 센서 및 IoT의 등장으로 대용량화된 공간 데이터로 인한 기존 공간 정보 처리 시스템의 성능적 한계를 극복하기 위한 목적으로 개발 중이다. 본 시스템은 효과적인 대용량 데이터 처리를 위해 현재 활발히 연구되고 있는 빅데이터 처리 기술과 공간 정보 처리 기술을 접목하여, 대용량의 공간 정보를 수집, 저장 관리하는 기능을 제공한다. 또한 효과적인 공간 데이터의 접근을 위해 스크립트 언어 기반의 공간 정보 처리 언어를 제공하고, SQL 형식의 선언적 공간 정보 질의 처리 기능도 제공하기 위해 개발 중에 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.761-764
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• 2005

컨텍스크 기반 미들웨어는 응용 도메인에서 실제 상황을 구현할 수 있다. 전형적으로 실제 위치를 환경에 메핑시킴으로서 실제상황을 가변적으로 변화시킬 수 있다. 또한 실제 위치에 센서와 actuator 를 이용한 서비스의 라이프사이클을 원격지에서도 가변적으로 변경할 수 있다. 이 시스템은 CAMUS[1] 시스템에서 라이프 사이클 관리를 OSGi 기반으로 한 내용을 구현하였다. OSGi 는 홈 네트워크 관련 개방형 시스템 게이트웨이 시스템으로서 OSGi 를 이용함으로써 다양한 유비쿼터스 통신, 가정, 컴퓨터 시스템간의 쉽게 라이프 사이클 관리를 할 수 있는 장점이 있다.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.46-51
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• 2010

A torsional guided wave was applied to detect a defect in petrochemical pipes. Phase and group velocity dispersion curves for the longitudinal and torsional modes of the inspected pipe were presented for the theoretical analysis. It was found through mode shape analysis that there was mode conversion when torsional wave is incident at an asymmetric defect. An artificial notch was fabricated in the pipe and the detectability was examined from the distance 2m of the end of the pipe by using magnetostrictive sensors. The relativities between the amplitude of the reflected signal and the size of the defect was examined. It was shown that the T(0,1) mode could be used for the long range inspection for the petrochemical pipes.