• 한국물환경학회지
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• 제18권3호
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• pp.283-290
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• 2002

In this study, home-made detection system by means of noble FIA is introduced on the measurement of toxic nitrite in the water samples collected from the area of Kwangju. As the standard calibration between 30 to 1000 ppb, the linearity has been shown more than 0.9999 as the correlation coefficient($R^2$) with the detection limit 1.5 ppb(S/N>2). The distribution of sample concentration was monitored as N.D. - 123 ppb which is wide span of concentrations in field water samples. The low level of nitrite is hardly detectable with other expensive sophisticated instruments including ion chromatography. Whereas the result of high concentration brings forth the necessity monitoring constantly our precious water resources. Successfully, the FIA system has played a very important role detecting wide span of nitrite in water sample. This technique can be adopted for controlling our environment in the near future.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1431-1440
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• 2024

The study aimed to develop a laser-based distance meter (LDM) to improve water surface identification for clinical MeV electron beam dosimetry, as inaccurate water surface determination can lead to imprecise positioning of ionization chambers (ICs). The LDM consisted of a laser ranging sensor, a signal processing microcontroller, and a tablet PC for data acquisition. I₅₀ (the water depth at which ionization current drops to 50 % of its maximum) measurements of electron beams were performed using six different types of ICs and compared to other water surface identification methods. The LDM demonstrated reproducible I₅₀ measurements with a level of 0.01 cm for all six ICs. The uncertainty of water depth was evaluated at 0.008 cm with the LDM. The LDM also exposed discrepancies between I₅₀ measurements using different ICs, which was partially reduced by applying an optimum shift of IC's point of measurement (POM) or effective point of measurement (EPOM). However, residual discrepancies due to the energy dependency of the cylindrical chamber's EPOM caused remained. The LDM offers straightforward and efficient means for precision water surface identification, minimizing reliance on individual operator skills.

• 한국항해학회지
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• 제15권2호
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• pp.87-96
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• 1991

The change of water level at Mokpo Harbour and its adjacent coastal area due to the construction of the Youngsan Estuary Barrage and the Third Land Reclamation Work of estuary barren had been roughly expected. Periodical floods, which occur 2 times per month, are also being observed at the low lying commercial areas near the Mokpo Old Harbor. Although it is said that the highest tidal current component among the tidal current records at the approaching channel to Mokpo Harbor is reduced to 6 kts, because of the esturary barrage, they do not give any precise statement or a deep analysis for the flooding and periodical water level change under certain environmental conditions. Moreover, they never tried the analysis of development plan considering the natural disaster such as typhoon or other extreme conditions. Thus, it is necessary to collect and analyze the data related to floodings, harbor oscillations, currents, and water quality , etc. because of the development considering the extreme condition. Thus, it is necessary to collect and analyze the data related to floodings, harbor oscillations, currents, and water quality, etc. because of the development considering the extreme condition and to evaluate the field observation and measurement, including the numerical model simulation based on the scientific approaches. This study deals the problem of the water level change among the integrated analyses of the coastal area changes. The result can be used for the integrated planning to give a strong foundation and it will contribute to the development of local area.

• 전기학회논문지
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• 제66권7호
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• pp.1149-1154
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• 2017

In this paper, we propose a sensorless multi-function controller applicable for deep well water pumps using current detection method. The proposed system overcomes various drawbacks of existing sensored system and additional features like Over current protection function due to overload, Under current protection function for idling at low water level and Relay function for starting single phase motors and acts as a level indicator to detect water lever in real time by the current detection method. A prototype of the multi-function controller system is designed and all of its functions are tested in the laboratory. The application of the proposed controller ensures reduction in the power consumption and maintenance cost in the facilities like water and septic tanks, drainage and waste water system, oil and chemical tanks where deep well pumps are used.

• 한국항공우주학회지
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• 제47권7호
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• pp.525-534
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• 2019

물로켓은 우주발사체와 동일한 기본원리를 가지는 가압식 액체추진제 로켓이다. 물로켓은 청소년용 과학교육 교보재 수준을 훨씬 넘어, 대학 수준의 액체 로켓 및 발사체 체계 공학 교육의 도구로 활용될 수 있다. 본 논문에서는 물로켓의 추진 및 비행 원리와 이론을 대학 학부의 로켓 공학 교육 수준에서 고찰하였다. 아울러 발사체와 발사대, 탑재체, 회수 및 고도 장치와 방법 등 체계 수준의 물로켓 설계와 운영에 대한 사항들을 정리하였다.

• 문화기술의 융합
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• 제2권4호
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• pp.55-59
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• 2016

본 논문에서는 물 부족, 불균형을 해결하기 위해 우수 이용률을 높이는 방법의 하나로 지하저류조를 설치하여 빗물을 저장하고, 관리하고자 하는 곳을 위한 저류조 수위의 모니터링과 제어에 대한 시스템을 제안하고 이를 구현하였다. 이를 위해 제어를 위한 모듈에는 ATMEL사의 Atmega 128의 마이크로프로세서를 사용하고 수위를 측정할 수 있는 센서는 접촉식 센서의 일종인 부자형태의 레벨센서를 사용하였다. 특히 레벨센서는 출력을 산업체 일반에서 많이 사용하는 크기로 출력하므로 기존의 센서를 대체할 수 있도록 호환성이 높도록 하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.7-10
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• 2005

Plant water deficiency during drought season causes physiological stress and can be a critical indicator of forest fire vulnerability. In this study, we attempt to analyze the spectral characteristics of water stressed vegetation by using the laboratory measurement on leaf samples and the canopy reflectance spectra extracted from satellite hyperspectral image data. Leaf-level reflectance spectra were measured by varying moisture content using a portable spectro-radiometer. Canopy reflectance spectra of sample forest stands of two primary species (pine and oak) located in central part of the Korean peninsula were extracted from EO-l Hyperion imaging spectrometer data obtained during the drought season in 2001 and the normal precipitation year in 2002. The preliminary analysis on the reflectance spectra shows that the spectral characteristics of leaf samples are not compatible with the ones obtained from canopy level. Although moisture content of vegetation can be influential to the radiant flux reflected from leaf-level, it may not be very straightforward to obtain the spectral characteristics that are directly related to the level of canopy moisture content. Canopy spectra form forest stands can be varied by structural variables (such as LAt, percent coverage, and biomass) other than canopy moisture content.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.264-271
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• 1999

The present experimental study is aimed to investigate the flow characteristics of the high-speed flow field within hot-water pump by PIV(Particle Image Velocimetry). As multi-point simultaneous velocity acquisition, 2-D PIV system based upon the two-frame gray-level cross correlation method is adopted using PC frame-grabber and simple video system. Gated image intensifier CCD Camera to cope with illumination problem is arranged for accurate PIV measurement of high-speed complex flow. The velocity vector distribution, velocity profile, and kinetic energy are represented quantitatively at the full-scale region for the deeper understanding of the unsteady flow characteristics in a pump.

• 한국수자원학회논문집
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• 제53권7호
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• pp.507-519
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• 2020

본 연구에서는 지각운동 모니터링과 지진발생 및 예측에 활용가능한 라돈 측정시스템을 개발하였으며, 라돈 측정시스템의 시범운영 결과와 지진발생 사례를 분석하였다. 첫 번째로, 개발된 라돈 측정시스템은 NB-IoT 라돈 측정기기, 데이터센터, 자료분석 및 자료제공 서버로 구성되며, NB-IoT를 활용하므로 측정된 자료의 원격전송이 가능하기 때문에 이 시스템은 무인 지하수관측소에 설치 및 운영에 매우 적합하다. 두 번째로 개발된 라돈 측정기기를 김포지역 지하수관측소에서 2019년 5월부터 7월까지 시범운영하였다. 측정된 라돈값을 지하수위와 전기전도도 측정자료와 비교하였으며, 본 연구에서 개발한 라돈 측정기기가 상용화하는데 어느 정도 가능성이 있음을 확인하였다. 마지막으로 2019년 11월부터 2020년 2월까지 3개 지진발생 사례와 Test-bed인 포항지역 지하수관측소에 설치된 NB-IoT 라돈 측정기기의 일단위 라돈 측정값, 일단위 지하수위, 일단위 전기전도도의 변동성을 비교·분석하였다. 분석결과, 지진발생이 라돈, 지하수위, 전기전도도와 어느 정도 상관관계가 있음을 확인하였으며, 본 측정자료가 향후 지진모니터링 및 예측에 도움이 되는 기초자료 제공이 가능함을 확인하였다

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.658-663
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• 1987

The new controller developed here, which is the facility with only one measurement, is a new concept for the level controller of the existing nuclear steam generator. A MACS (Microcomputer-based Adaptive Control System of a Steam Generator) is quite practical and efficient, and has also simple structure and higher flexibility in the installment for actual plant. A key ingredient of this system is adaptive regulator which can calculate adaptive, optimal valve position in response to changes in the dynamics of the process and the disturbances. In spite of many difficulties in the steam generator water level control at low power, it can be concluded from the experimental and simulation results, that the MACS can provide optimal, robust steam generator level control from zero to full power. The amount of the control input effort can be reduced by adjusting the weighting factor. However, the steady state water level errors are generated. To avoid the steady errors, the different adaptive algorithm should be investigated in the future. The 3 second sampling time is acceptable for this system. However, action should be taken to shorten the sampling time for better digital control.