• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.305-312
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• 2021

There is a gradual increase in the need for energy charging in marine environments because of energy limitations experienced by electric ships and marine robots. Buoys are considered potential energy charging systems, but there are several challenges, which include the need to maintain a fixed position and avoid hazards, dock with ships and robots in order to charge them, be robust to actions by birds, ships, and robots. To solve these problems, this study proposes a smart buoy robot that has multiple thrusters, multiple docking and charging parts, a bird spike, a radar reflector, a light, a camera, and an anchor, and its mechanism is developed. To verify the performance of the smart buoy robot, the position control under disturbance due to wave currents and functional tests such as docking, charging, lighting, and anchoring are performed. Experimental results show that the smart buoy robot can operate under disturbances and is functionally effective. Therefore, the smart buoy robot is suitable as an energy charging system and has potential in realistic applications.

• Journal of environmental and Sanitary engineering
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• v.23 no.1
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• pp.1-15
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• 2008

Yanbian Korean Autonomous Prefecture(YKAP) possesses the potential to become the first testing ground for the North-East Asian Energy Cooperation in renewable energy sector. We found that production of biodiesel from rapeseed and CHP (Combined Heat and Power Plant) project utilizing abundant forest resources are the two main bioenergy development projects which may have further development potential considering the resource endowments and the focus of Chinese governments' current rural development policy. Provision of stable and transparent investment environments and the development of a close cooperation mechanism between Korea and China government are the prerequisite conditions for investments in the sector. Other international institutional agreements, such as CDM, shall be fully utilized for biomass CHP projects.

• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.280-294
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• 2022

This study reviews the recent development and research results of a fixed oscillating water column (OWC) wave energy converter (WEC). The OWC WEC can be divided into fixed and floating types based on the installation location and movement of the structure. In this article, the study on a stationary OWC WEC, which is close to commercialization through the accumulation of long-term research achievements, is divided into five research categories with a focus on primary energy conversion research. These research categories include potential-flow-based numerical analysis, wave tank experiments, computational fluid dynamics analyses toward investigation of fluid viscous effects, U-shaped OWC studies that can amplify water surface displacement in the OWC chamber, and studies on OWC prototypes that have been installed and operated in real sea environments. This review will provide an overview of recent research on the stationary OWC WEC and basic information for further detailed studies on the OWC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1854-1868
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• 2018

A wireless body-sensor network (WBSN) refers to a network-configured environment in which sensors are placed on both the inside and outside of the human body. The sensors are much smaller and the energy is more constrained when compared to traditional wireless sensor network (WSN) environments. The critical nature of the energy-constraint issue in WBSN environments has led to numerous studies on the reduction of energy consumption of WBSN sensors. The transmission-power-control (TPC) technique adjusts the transmission-power level (TPL) of sensors in the WBSN and reduces the energy consumption that occurs during communications. To elaborate, when transmission sensors and reception sensors are placed in various parts of the human body, the transmission sensors regularly send sensor data to the reception sensors. As the reception sensors receive data from the transmission sensors, real-time measurements of the received signal-strength indication (RSSI), which is the value that indicates the channel status, are taken to determine the TPL that suits the current-channel status. This TPL information is then sent back to the transmission sensors. The transmission sensors adjust their current TPL based on the TPL that they receive from the reception sensors. The initial TPC algorithm made linear or binary adjustments using only the information of the current-channel status. However, because various data in the WBSN environment can be utilized to create a more efficient TPC algorithm, many different types of TPC algorithms that combine human movements or fuse TPC with other algorithms have emerged. This paper defines and discusses the design and development process of an efficient TPC algorithm for WBSNs. We will describe the WBSN characteristics, model, and closed-loop mechanism, followed by an examination of recent TPC studies.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.274-281
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• 2011

High-speed telecommunication systems are influenced by electromagnetic environments because they need a wide bandwidth to transmit signals. Immunity tests of telecommunication equipment are effective for improving its immunity to electromagnetic environments. However, immunity tests are expensive to carry out because there are several different tests. The correlation among the tests should therefore be examined in order to reduce the kinds of tests that are necessary. This paper investigates the correlation between the electrical fast transient/burst (EFTB) test and the radio frequency (RF) conductive immunity test. Imitation equipment was constructed with a balun, and a baseband signal was transmitted from the associated equipment to the imitation equipment. Then, disturbances were applied to the equipment, and the telecommunication quality was evaluated by using the bit error rate (BER). The results from the EFTB test indicated that the BER was less than $6{\times}10^{-5}$ and the value was independent of the peak value. The results from the RF conductive immunity test indicated that the BER was affected by the longitudinal conversion loss (LCL).

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.199-201
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• 2016

Wireless sensor networks offer an attractive solution to several environments, security, and process monitoring problems. However, one barrier for their full adoption is the need to provide electrical power over extended periods of time without the need of dedicated wiring. Energy harvesting offers good solutions to this problem in several applications. This paper surveys the energy requirements of typical sensor network nodes and summarizes the future research work in the field of energy harvesting resource allocation in wireless sensor networks.

• Corrosion Science and Technology
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• v.11 no.5
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• pp.196-204
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• 2012

Corrosion failure of petrochemical facilities is one of the difficulties in maintenance, since operating conditions of crude oil production, storage, and refinement are very aggressive. UNS N08810, which has been used for crude oil transportation pipes and storage tanks in petrochemical industries, shows good resistance to general corrosion and localized corrosion in several environments. Among its environments, UNS N08810 showed better corrosion resistance in fuel gas containing sulfuric acid and phosphoric acid and sulfur. However, ductility and toughness at high temperature over about $500^{\circ}C$ were greatly reduced due to microstructural change. In general, welding process is the representative method to join the parts in industrial components. Because the alloy by welding can be sensitized and corroded, the manufacturing process should be controlled. In this work, UNS N08810 was used and heat treatment conditions including solution and stabilization treatments were controlled. Oxalic acid etch test by ASTM A262 Practice A was done to evaluate the qualitative sensitization in room temperature. Huey test by ASTM A262 Practice C was done to evaluate the intergranular corrosion rate in boiling 65% $HNO_3$ solution. Also, the microstructure by thermal history was analyzed. Experimental alloy showed high intergranular corrosion rate and its corrosion mechanism was elucidated.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.97-109
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• 2022

Species are facing strong selection pressures to adapt to inhospitable high-altitude environments. Yaks are a valuable species and an iconic symbol of the Qinghai-Tibet Plateau. Extensive studies of high-altitude adaptation have been conducted, but few have focused on metabolism. In the present study, we determined the differences in the serum metabolomics between yaks and the closely related species of low-altitude yellow cattle and dairy cows. We generated high-quality metabolite profiling data for 36 samples derived from the three species, and a clear separation trend was obtained between yaks and the other animals from principal component analysis. In addition, we identified a total of 63 differentially expressed metabolites among the three species. Functional analysis revealed that differentially expressed metabolites were related to the innate immune activation, oxidative stress-related metabolism, and energy metabolism in yaks, which indicates the important roles of metabolites in high-altitude adaptation in yaks. The results provide new insights into the mechanism of adaptation or acclimatization to high-altitude environments in yaks and hypoxia-related diseases in humans.

• International journal of advanced smart convergence
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• v.8 no.1
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• pp.82-86
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• 2019

We aim to use public data different from the remote BEMS energy diagnostics technology and already established and then switch the conventional operation environment to a big-data-based integrated management environment to operate and build a building energy management environment of maximized efficiency. In Step 1, various network management environments of the system integrated with a big data platform and the BEMS management system are used to collect logs created in various types of data by means of the big data platform. In Step 2, the collected data are stored in the HDFS (Hadoop Distributed File System) to manage the data in real time about internal and external changes on the basis of integration analysis, for example, relations and interrelation for automatic efficient management.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.79-88
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• 2012

Migration tests were performed with conservative tracers in a fractured zone that had a single fracture of about 2.5 m distance at the KURT. To interpret the migration of the tracers in the fractured rock, a solute transport model was developed. A two dimensional variable aperture channel model was adopted to describe the fractured path and hydrology, and a particle tracking method was used for solute transport. The simulation tried not only to develop a migration model of solutes for open flow environments but also to produce ideas for a better understanding of solute behaviours in indefinable fracture zones by comparing them to experimental results. The results of our simulations and experiments are described as elution and breakthrough curves, and are quantified by momentum analysis. The main retardation mechanism of nonsorbing tracers, including matrixdiffusion, was investigated.