• Journal of Advanced Marine Engineering and Technology
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• v.37 no.3
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• pp.266-273
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• 2013

With the worldwide trend of controlling the utilization of fossil fuels inducing global climate change, many efforts will have to be made on securing a sustainable energy supply. Tidal current is a concentrated form of gravitational energy, its resource is significant, but limited locations. To effectively capture tidal current energy from the sea, a group of tidal turbines should be formed and positioned with optimal size and spacing for absorbing from multiple points. Thus, the flow field including turbines becomes a huge domain, a so-called tidal farm. It can be very convenient technically and economically if a whole turbine farm is simulated by means of actuator disc thoery. So, the analysis method using actuator discs coupled with a solution of Reynolds Averaged Navier-Stokes (RANS) equations is adopted for actual tidal turbines. Actuator discs have regions where similar forces imposed by actual turbines are applied to a flow. As working in group formation, turbines naturally have interaction effects on one another. Therefore, the present paper investigate the evaluation on the operating performance of tidal farm in terms of the mutual influence among turbine units with various lateral and longitudinal spacing. Authors expect that results of the present study contribute to the development of tidal farm for the future potential energy.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.235-242
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• 1998

Aiming at one of decisive alternatives for long term aspect of nuclear power concerns, an integral and closed nuclear system, AMBIDEXTER (Advanced Molten-salt Break-even Inherently-safe Dual-mission Experimental and TEst Reactor) concept is under development. The AMBIDEXTER complex essentially comprises two mutually independent loops of the radiation/material transport and the heat/energy conversion, centered at the integrated reactor assembly, which enables one to utilize maximum benefits of nuclear energy under minimum risks of nuclear radiation. And it provides precious radioisotopes and radiation sources from its waste stream. Also the reactor operates at very low level of fission products inventory throughout its lifetime. The nuclear and thermalhydraulic characteristics of the molten TH/$^{233}$ U fuel salt extend the capability of the self-sustaining AMBIDEXTER fuel cycle to enhance resource security and safeguard transparency. The reactor system is consisted of a single component module of the core, heat exchangers and recirculation pumps with neither pipe connections nor active valves in between, which will significantly improve inherent features of nuclear safety. States of the core technologies associated with designing and developing the AMBIDEXTER concept are mostly available in commercialized form and thus demonstration of integral aspects of the concept should be the prime area in future R＆D programs.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.155-162
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• 2010

Recently, due to high oil prices and environmental pollution issues, interest of alternative energy development increases and the related research is widely conducted. Among those research activities the tidal stream power generation utilizes the tidal flow as its mechanical power resource and less depends on the environmental condition for installation and operation than other renewable energy resources. Therefore the amount of power generated is quite consistent and straightforward to predict. However, research on the tidal stream energy conversion turbine is rarely found. In the present study, two numerical methods were developed and compared for the open water Momentum Theory, which is widely used for wind turbines, was adopted. The moving reference frame method for Computational Fluid Dynamis solver were also used. Hybrid meshing was used for the complex geometry of turbines. The analysis results using each method were compared to figure out a better method for the performance prediction.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.48-53
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• 2008

The performances of the building service equipment relay on the individual superintendent's share for the assessment of performance, fault detection, deterioration diagnosis of the building service equipment. A major use of building energy management system(BEMS) is for monitoring plant and building's energy consumption. National building management system (N-BMS) presented in this study links buildings into a network group in order to monitor and control the buildings. How to construct the N-BMS was considered to save energy resource and to conserve performance of building service equipment. The FEMIS, facility, energy/environmental management & information system, for building service offer management process integrated with BAS, FMS and EMS and so on.

• International journal of advanced smart convergence
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• v.7 no.1
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• pp.1-6
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• 2018

In addition to the instability of energy import costs caused by the depletion of petroleum resources, which is a representative energy resource, and the strengthening of various regulations such as the convention on climate change, the plant for bio energy production, which is being watched as the next generation energy, and became subject of various complaints. In order to solve this problem, the bio-plant is underground and the ground is parked, making the convenience and accessibility of citizens more and more accessible. In this situation, the development of bioenergy production technology also increases the risk factor in bioenergy production process. Accordingly this paper explains method about apply the wide angle camera based AOA algorithm to the bio plant to prevent the accidents from spreading due to the lack of facilities and safety devices and the aging of the facilities and suggests a technique that can quickly identify the location and direction when it occurs.

• New & Renewable Energy
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• v.17 no.1
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• pp.7-18
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• 2021

This study analyzes the role of market actors in the energy transition process and the interaction between them and ordinary citizens, primarily focusing on the mini-PV project in Seoul. The study also proposes measures to harness market actors' activities and successfully implement the distribution of mini-PV systems in Seoul. In this study, practice theory is used as a theoretical resource to analyze the interaction between market actors and civil society actors and to help understand how market actors influence the decisions of regular citizens in installing mini-PV at their properties. After conducting surveys and hosting in-depth interviews with ordinary citizens and market actors, it was found that to further promote the role of market actors, the Seoul Metropolitan Government should actively support and monitor the public relations activities of market actors, while concurrently managing selected companies and establishing relevant administrative systems for continued effective use post-installation of mini-PV systems. In future studies of the energy transition process, market actors should also be recognized as key players, along with government and civil society actors, and their roles should be studied in a balanced way.

• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.1-23
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• 2022

For its essential importance as a resource, sustainable development of groundwater has been major research interests for many decades. Conventional characterization of aquifer and groundwater has relied on borehole data from observation well. Although borehole data provide useful information on yield and flow of groundwater, it is often difficult and sometimes costly to estimate the spatial distribution of groundwater in entire aquifer. Geophysical probing is an alternative techique that provides such information due to its capability to image subsurface structures as well as to delineate spatial distribution of hydraulic parameters. This study presents various technical information about geophysical probing to estimate main characteristics of aquifer for groundwater exploitation. Subsequently, we analyzed representative cases, in which geophysical methods were applied to identify the location of the groundwater, classify freshwater and brine, derive hydraulic constants, and monitor groundwater.

• Journal of Agricultural Extension & Community Development
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• v.6 no.2
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• pp.3-15
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• 1999

The objectives of this study were 1) to review the developmental process of agricultural extension services since 1960 in Korea, and 2) to suggest new paradigm of agricultural extension education in the 21st century. The study suggested major objectives of agricultural extension service in Korea should be focused on; 1) Agricultural technology transfer for environmentally friendly food production, 2) Diffusion of energy saving and safe farming technologies and upbringing export oriented agriculture, 3) Education and training of capable farmers for competitive world, and 4) Technological support for home improvement considering harmony of human, environment and life. To achieve major objectives of extension services the following strategies should be employed; 1) National administration and financing. 2) Farmer oriented services should be performed since extension education is originally two-way communication process to help farmers in better decision making, 3) Human resource development for extension educators to meet increasing demands of target population, and policy measures should be implemented to increase morale of extension educators, and 4) Role of public extension should be strengthened to meet needs of majority farmers and public interests in the knowledge based information society in the 21st century.

• International Journal of Contents
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• v.13 no.4
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• pp.39-46
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• 2017

Due to resource constraints, most of Android application developers need to address potential performance problems during application development and maintenance. The coding styles and patterns of Android programming could often affect the execution time and energy efficiency which are utilized by the Android applications. Thus, it is necessary for application developers to apply performance-enhancing programming practices for mobile application development. This paper introduces performance-enhancing best practices for Android programming, and further, it evaluates the impact of these practices on the CPU time of the application. The original version with the performance-worsening code has been refactored to become an efficient version without changing its functionality. To demonstrate the efficiency of the proposed approach, each coding pattern was evaluated by measuring the CPU time under the controlled runtime environment. Furthermore, the Android applications were evaluated and compared via the CPU time of the original version, with that of the refactored version. These experimental results indicate that, by -using the proposed programming practices, the Android developer can develop performance-efficient mobile applications.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.242-257
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• 2022

Microalgae is becoming a vital component for a circular economy and ultimately for sustainable development. Herein, recent developments in different outcomes of microalgae for wastewater treatment and biorefinery were reviewed. From its primary function as a third-generation resource of biofuel, the usage of microalgae has been diversified as an integral element for the CO₂ sequestration and production of economically valuable products (e.g., pharmaceuticals, animal feeds, biofertilizer, biochar, etc.). Principles and recent challenges for each microalgae application were presented to suggest a motivation for future research and the direction of development. The integration of microalgae within the concept of the circular economy was also discussed with various routes of microalgae-based biorefinery.