• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1443_1444
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• 2009

A study on the environmental tests for auxiliary and control circuits of high voltage switchgears, especially testing condition and requirements, according to the relevant international standards has been briefly reviewed in this paper. As the highest supply voltage of electric power systems have been progressed, testing techniques and testing standards such IEC codes improved and revised keeping step with it. Especially IEC 62271 series, which are applicable to the HV-class switchgears and controlgears have been revised in 2008 newly. In this paper, the special consideration and background information of environmental testing condition with mechanical operating performance, e.g. operation in a higher and lower ambient temperature, for the auxiliary and control circuits of switchgears and controlgears and considerable investigation to the related international standards have been provided. Examples of testing performed were showed and analysis of their test results have been described.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.667-675
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• 2013

This paper presents vision-based techniques for underwater landmark detection, map-based localization, and SLAM (Simultaneous Localization and Mapping) in structured underwater environments. A variety of underwater tasks require an underwater robot to be able to successfully perform autonomous navigation, but the available sensors for accurate localization are limited. A vision sensor among the available sensors is very useful for performing short range tasks, in spite of harsh underwater conditions including low visibility, noise, and large areas of featureless topography. To overcome these problems and to a utilize vision sensor for underwater localization, we propose a novel vision-based object detection technique to be applied to MCL (Monte Carlo Localization) and EKF (Extended Kalman Filter)-based SLAM algorithms. In the image processing step, a weighted correlation coefficient-based template matching and color-based image segmentation method are proposed to improve the conventional approach. In the localization step, in order to apply the landmark detection results to MCL and EKF-SLAM, dead-reckoning information and landmark detection results are used for prediction and update phases, respectively. The performance of the proposed technique is evaluated by experiments with an underwater robot platform in an indoor water tank and the results are discussed.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.705-716
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• 2011

For the efficient discovery of knowledge and information from the observed systems, data mining techniques can be an useful tool for the prediction of water quality at intake station in rivers. Deterioration of water quality can be caused at intake station in dry season due to insufficient flow. This demands additional outflow from dam since some extent of deterioration can be attenuated by dam reservoir operation to control outflow considering predicted water quality. A seasonal occurrence of high ammonia nitrogen ($NH_3$-N) concentrations has hampered chemical treatment processes of a water plant in Geum river. Monthly flow allocation from upstream dam is important for downstream $NH_3$-N control. In this study, prediction models of water quality based on multiple regression (MR), artificial neural network and data mining methods were developed to understand water quality variation and to support dam operations through providing predicted $NH_3$-N concentrations at intake station. The models were calibrated with eight years of monthly data and verified with another two years of independent data. In those models, the $NH_3$-N concentration for next time step is dependent on dam outflow, river water quality such as alkalinity, temperature, and $NH_3$-N of previous time step. The model performances are compared and evaluated by error analysis and statistical characteristics like correlation and determination coefficients between the observed and the predicted water quality. It is expected that these data mining techniques can present more efficient data-driven tools in modelling stage and it is found that those models can be applied well to predict water quality in stream river systems.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.4
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• pp.255-265
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• 2024

To address environmental challenges and improve energy efficiency, the adoption of electric vehicles has led to a surge in related research. However, to comprehensively understand the research trends within the field of electric vehicles, it is necessary to systematically analyze vast amounts of data. This study systematically analyzed research trends in the field of electric vehicles and identified key research topics through LDA topic modeling, based on 36,519 papers related to electric vehicles collected from the SCIE database. The data analysis revealed a total of 10 major topics, of which three were identified as hot topics showing an upward trend: Electric Vehicle Charging Infrastructure, Energy and Environmental Policy, and Optimization and Algorithms. Conversely, five topics were identified as cold topics exhibiting a downward trend: Battery Temperature and Cooling, Battery Materials and Chemistry, Motor and Mechanical Design, Control Strategies and Systems, and Battery Components and Materials. This study provides basic data for understanding the current research trends in electric vehicles and offers valuable information for researchers in selecting research topics related to electric vehicles.

• Journal of Korean Society on Water Environment
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• v.40 no.2
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• pp.89-100
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• 2024

Climate change has a broad impact on the entire water environment, and this impact is growing. Climate adaptation in water supply systems often involves quantity and quality control, but there has been a lack of research examining the impacts of climatic factors on water supply productivity and operation conditions. Therefore, the present study focused on, first, building a database of climatic factors and water purification operating conditions, and then identifying the correlations between factors to reveal their impacts. News big data was analyzed with keywords of climatic factors and water supply systems in either nationwide or region-wide analyses. Metropolitan area exhibited more issues with cold waves whereas there were more issues with drought in the Southern Chungcheong area. A survey was conducted to seek experts' opinions on the climatic impacts leading to these effects. Pre-chlorination due to drought, high-turbidity of intake water due to rainfall, an increase of toxins in intake water due to heat waves, and low water temperature due to cold waves were expected. Pearson correlation analysis was conducted based on meteorological data and the operating data of a water purification plant. Heavy rain resulted in 13 days of high turbidity, and the subsequent low turbidity conditions required 3 days of high coagulant dosage. This insight is expected to help inform the design of operation manuals for waterworks in response to climate change.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.6
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• pp.88-98
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• 2007

The control of nonpoint source pollution from the urban paved areas with high imperviousness in is required to improve the water quality of aquatic resources. This research investigated the characteristics of urban runoffs and evaluate the effectiveness of the continuous deflective separation systems for stormwater best management practice. The systems were installed in the vicinity of a high-level road, an apartment complex, and the Cheonggye stream. Stormwater runoff was sampled in these sites. Biochemical oxygen demand ($BOD_5$), total suspended solid (TSS), total nitrogen (T-N), and total phosphorus (T-P) were analyzed. The removal efficiency of $BOD_5$, TSS, and T-P for the road was 10.9-81.0%, 11.7-93.4%, 0-37.5%, respectively. That of $BOD_5$, TSS, T-N, and T-P for the complex was 12.5-65.8%, 26.5-77.6%, 1.8-28.7%, and 20.0-37.5%, respectively. The abatement efficiency $BOD_5$, TSS, T-N, and T-P for the stream was 7.2-85.2%, 41.7-98.2%, 11.3-65.6%, and 2.0-71.5%, respectively. This study shows that the systems can be used to remove $BOD_5$ and TSS from urban runoffs efficiently.

• Journal of Drive and Control
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• v.17 no.2
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• pp.45-54
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• 2020

The IMV is a combination of four two-way valve systems which replace a conventional four-way spool valve to improve efficiency mostly in excavator hydraulics. As the environmental regulations for construction equipment have tightened, some overseas advanced companies have released commercial excavators in which the MCV is implemented with the IMVs. Development of the IMV type MCV relies on the control algorithm as well as the robust performance of proportional flow control valves. In this study, the IMV controller was designed and verified with experiments for the excavator working unit, which determines the IMV mode of operation and the extent of the valve opening in consideration of the load conditions on hydraulic actuators. First, the open-loop controller was designed with a joystick command vs. a PSV reference current map comprising several control parameters in to compensate for the different flow characteristics and non-linearities of two-way flow control valves. Second, the closed-loop controller was designed with the PI control fed by the actuator displacement and outputs actuator percent effort equivalent to the operator's joystick command. Finally, the performance of the IMV type MCV was verified with the trajectory control of position references derived from the energy consumption test standard. Experimental results showed the control performance of the IMV developed in this study, and suggest that future studies to be conducted to advance technical progress.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2278-2282
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• 2003

In this paper the structure of 2-DOF controller based on artificial immune network algorithms has been suggested for nonlinear system. Up to present time, a number of structures of the 2-DOF controllers are considered as 2-DOF (2-Degrees Of Freedom) control functions. However, a general view is provided that they are the special cases of either the state feedback or the modification of PID controllers. On the other hand, the immune network system possesses a self organizing and distributed memory, also it has an adaptive function by feed back law to its external environment and allows a PDP (parallel distributed processing) network to complete patterns against the environmental situation, since antibody recognizes specific antigens which are the foreign substances that invade living creatures. Therefore, it can provide optimal solution to external environment. Simulation results by immune based 2-DOF controller reveal that immune algorithm is an effective approach to search for 2-DOF controller.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.37-43
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• 1999

This study was conducted to develop the simple and convenient irrigation control model which can maintain the appropriate rates of irrigation and drainage of nutrient solution according to the enviornmental conditions and growth stages in soilless culture of cucumber. In order to obtain fundamental data for development of the model, investigation of the actual state of soilless culture practices was carried out. Most irrigatioin systems of soillness culture were controlled by the time colock. Evapotranspiration of cucumber in soilness culture was investigated and correlations with environmental conditions were analyzed , and its estimating model was developed. In order to develop the irrigation system which can control the amount of nutrient solution applied according to seasons, weather conditions, and growth stages, a irrigation clock control was developed. Applicability of the model was tested by simulation. Drainage rates of nutrient solution controlled by conventional time clock, integrated solar radiation, and the developed model were 61% , 20%, and 32% , respectively in cucumber perlite culture.

• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.243-248
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• 1995

Agrochemicals for the plant-disease control are criticized severely for causing environmental pollution and residual problems, and consequently microbial disease control agents are expected to be safer and more economical for sustainable agriculture. Treatment of biological control agents to seed requires the use of effective delivery systems that allow full expression of the benefical qualities of the bioprotectant. For the activation and establishment of bioprotectant around the plant seed which are able protect the seeds and seedlings from pathogen attack, the optimal liquid coating formulation was obtained using 2% sodium carboxymethyl cellulose (binder), 20% sesame dregs (solid particulate material), and dried spore of Bacillus subtilis YBL-7 (bioprotectants, 10 mg/g of seed). Suppressive of root rot was demonstrated in pot trials with coated kidney bean (Phaseolus vulgaris L.) seeds. Coated seeds with B. subtilis YBL-7 spore in F. solani-infested soil reduced disease incidence by 85% to 90% after 30 days.