• Ocean and Polar Research
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• v.45 no.2
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• pp.33-42
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• 2023

Dissolved oxygen (DO) is a crucial parameter for assessing environmental conditions in aquatic ecosystems. However, commercial in situ dataloggers for oxygen optodes can be relatively expensive and limited in their specifications. In this paper, we present a novel design for a DO datalogger system based on the control boards family with RP2040 MCU chipset. Our design includes two types of dataloggers: a simple logging system and a programmable system for sampling rates via magnetic switches underwater for divers. We provide detailed descriptions of the system, including the MicroPython source code and drawings to aid in construction. We also discuss the various applications of our DO datalogger system in monitoring dissolved oxygen concentration in coastal waters and assessing the benthic metabolism of aquatic ecosystems. Our DO datalogger system provides an affordable and flexible option for researchers to accurately monitor DO concentrations in aquatic environments, and thereby improve our understanding of these complex ecosystems.

• Journal of Environmental Impact Assessment
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• v.16 no.2
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• pp.143-156
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• 2007

This study has researched the management status and the pollution level of water, soil, stream sediments of 11 abandoned coal mines out of a total of 12 within Obong-Dam area except Bukyung mine, which was submerged when constructing Obong-Dam, and selected areas which are in needs to have pollution control facilities in the first place. From the results of examination on the runoff at the waste rock pile and mineheads, the runoff from Sueun mine (pH, Fe, Al), Samwon mine (pH, Al), Wangdo mine (pH, Al), Mose mine (pH, Fe, Al) and Daeryeong mine (pH) exceeded the permissible discharge standards of the water quality, but the water at merging point with Obong-Dam after joined with Doma branch satisfied both Water Quality Standards and Drinking Water Quality Standards. In regard to groundwater contamination, it is found that areas where exceeded the Drinking Water Quality Standards are Wangdo mine (pH), Jangjae mine (pH, Zn), Daeryeong mine (pH) whereas all areas satisfied Soil Contamination Warning Standards of Soil Environmental Conservation Law. When comparing a research result on underwater sediments of branches of abandoned mines to the EPA Guidelines for classification of great lakes harbor sediments, Dongguk Gaerim (Fe), Jungwon mine (Fe), Daebo mine (Mn), Samwon mine (Mn) and Daeryeong mine (Mn) showed mid-level of contamination, whereas Sueun (Fe, Mn), Daebo mine (Fe), Woosung mine (Fe, Mn), Wangdo mine (Fe, Mn), Mose mine (Fe) and Daeryeong mine (Fe) showed high-level of contamination. In addition, contamination levels of underwater sediments in Wangsan and Doma branch where abandoned mine's branches merge together, Wangsan branch showed no contamination at all whereas Doma branch shows mid-level of contamination which reflect the Doma branch is affected by waste rock pile and minehead runoff of the abandoned mines in the Doma branch area. It is concluded that Mose mine and Sueun mine required treatment of acid mine drainage. and Wangdo, Jungwon, and Samwon mines were in need of mine tailing and erosion control work. The Samwon mine additionally required a control system for closed minehead runoff. Although the Samwon mine reached a high concentration of Al, Mn $Ca^{2+}$, $SO{_4}^{2-}$ in the runoff, the levels decreased after it was combined with a tributary. It has been concluded that after further monitoring of the cause of pollution, a preventive measure system may be needed to be built.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1669-1676
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• 2020

The IAEA held the IAEA Robotics Challenge 2017 (IRC2017) to protect workers during inspections of spent nuclear fuel and to improve work efficiency and accuracy rates. To this end, we developed an unmanned surface vehicle (USV) system called the spent fuel check vehicle (SCV). The SCV extracts and tracks the target through image processing, and it is necessary to find suitable parameters for the SNF storage environment in advance. This preliminary work takes time. It is also difficult to prepare the environment in which the work will proceed. In addition, if the preliminary work does not proceed as planned, the system will not move at the proper speed and will become unstable, with yawing and overshoot. To solve this problem, we developed a controller with a camera that can extract the depth at which the target is stored and allow distance-adaptive control. This controller is able to attenuate system instability factors such as yawing and overshoot better than existing controllers by continuously changing system operation parameters according to the depth. In addition, the time required for preliminary work during inspections can be shortened.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.766-770
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• 2013

This paper tried to develop a BLDC electric motor securing the 800 W-level watertight structure for driving the outboard motor. For this purpose, this paper developed a high-efficient controller-integrating BLDC electric motor system for underwater propulsion and designed and developed a triple watertight structure. Besides, this study developed a outboard motor integrating motor, propeller and controller based on the production of a controller for BLDC motor which can the speed control by selecting low-voltage, high-current power element. The characteristics of developed outboard motor were 24 V input voltage, over 800 W motor output, and max. 3,000 rpm motor, and 84.9% motor efficiency, and the developed outboard motor could secure the watertight structure in 5 m in water depth.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.441-444
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• 1992

In this paper, for tracking and filtering seaway information which act as a control disturbance the adaptive notch filter which removes disturbance with fast convergence and stability without changing the value of gain parameter $\mu$ when statistical property of input signal varies rapidly is designed by improving conventional RMXMS(Recursive Maximum Mean Square) algorithm. Besides, in consideration of measurement noise of sensors in underwater vehicle, the system which removes the noise and the disturbance is suggested.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2466-2468
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• 2002

원자력 발전소 중 가동년수가 오래된 발전소에서는 원자로 압력용기의 상부와 하부구조물 등에서 일부부품이 이탈되어 주 냉각재 순환계통의 주요기기를 손상시키는 사례가 있으며, 부품의 미소 결함의 정밀검사는 육안으로는 판단이 불가능하므로 원전 설비의 안정성과 신뢰성 확보 측면에서 로봇을 응용한 정밀검사가 요구되어진다. 본 논문에서는 원자로 압력용기 육안검사용 수중로봇 시스템을 설계 제작하고, 제어시스템을 구현하고, 실험을 통해 제작 구현한 수중로봇 시스템의 효용성을 보인다.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.267-273
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• 2020

Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.291-299
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• 2010

As recent advances in science, technology and performance requirements of the weapons system are getting highly diversified and complex, the performance requirements also get stringent and strict. Moreover, the weapons system should be intimately connected with other systems such as watchdog system, command and control system, C4I system, etc. However, a tremendous amount of time, cost and risk being spent to acquire new weapons system, and not being diminished compared to the rapid pace of its development speed. Defense Modeling and Simulation(M&S) comes into the spotlight as an alternative to overcoming these difficulties as well as constraints. In this paper, we propose the development process of virtual test framework based on the synthetic environment as a tool to analyze the effectiveness of the weapons system of underwater engagement model. To prove the proposed concept, we develop the test-bed of virtual test using Delta3D simulation engine, which is open source S/W. We also design the High Level Architecture and Real-time Infrastructure(HLA/RTI) based Federation for the interoperation with heterogeneous simulators. The significance of the study entails (1)the rapid and easy development of simulation tools that are customized for the Korean Theater of War; (2)the federation of environmental entities and the moving equations of the combat entities to manifest a realistic simulation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.151-151
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• 2023

An accurate prediction of the hydrodynamic maneuvering darivatives is essential to desing a robust control system of a UUV(unmanned underwater vehicle). Typically, these derivatives were estimated by either the towing tank experiment or semi-empirical methods. With the enhancement of high performance computing capacity, a numerical analysis using computational fluid dynamics has reach the level of experiment. Therefore, the aims of the present research are to numerically develop a computational model for the vertical planar motion mechanism of a UUV and to estimate the hydrodynamics loads in 6-DOF. The target structure of the present study was manta type UUV (12meter length). The numerical model was developed in 1/ 6 model scale. Numerical results were compared with the results of the towing tank experiment for validation. In the present study, a commercial RANS-based viscous solver STARCCM+ (ver 17.06) was used.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.4
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• pp.241-248
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• 2023

Despite the recent short history of drones, the applying field of drones has been used for various purposes in a wide variety of areas and fields. As such, with the emergence of various types of drones over the years, in a broad sense, a remote controlled mobile object that can be controlled by wired and wireless control may be a suitable definition for drone because of various types of drones in recent years. This paper aims to help readers who want to research, develop, and use drones by examining the history, application fields, and future prospects of drones, including Unmanned Surface Vehicle(USV) and Unmanned Underwater Vehicles(UUV), as well as aerial type drones. Through this paper, it is expected that these drones will continue to be used in various fields in the future, and the prospect of future development will continue constantly. However, for the development of domestic drone technology and industry, the government's improvement in drone-related regulations should be supported.