• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.325-334
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• 2017

This paper reports the conceptual design process for a floating metocean data measurement system (FMDMS) for measuring wind information at sea. The FMDMS consists of three circular pontoons, columns, and a deck, which the LiDAR (lighting detection and ranging) is installed on. The dynamics of the mooring lines and motion responses of the FMDMS were analyzed using commercial codes such as WAMIT and OrcaFlex. One design criterion of the developed FMDMS was to maintain the motion responses as small as possible to enhance the LiDAR's accuracy. Starting with the preliminary design parameters such as the FMDMS's principal dimensions, weight, and important parameters of mooring system, we checked whether the FMDMS met the design requirements at each design stage, and then made modifications as necessary. The developed FMDMS showed a large pitch behavior for a small heave motion.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.1-17
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• 2014

Domestic and international energy and eco-friendly companies take advantage of social media for image enhancement and product promotion. However, there were no in-depth empirical analysis to verify specific effectiveness of social media use in these sectors. The purpose of this study is to reveal the key factors that are considered to use social media effectively for energy and eco-friendly companies. For this purpose, we regarded the effectiveness of social media as Post Awareness and Word of Mouth. Characteristics of social media as a medium were measured separately, media richness and media genre, as independent variables of social media effectiveness. We investigated 413 posts in Facebook brand page of energy and eco-friendly companies and conducted a content analysis. As a result, post awareness of users was greater when post has richer media such as video. For media genre, word of mouth appeared to be greater when the posts provide information.

• Journal of Hydrogen and New Energy
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• v.20 no.2
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• pp.104-115
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• 2009

In case of residential fuel cell system, it is significant to stably supply heat and power to a house with high efficiency and low cost for the successful commercialization. In this paper, the control strategy analysis has been performed to minimize the total cost including capital and operating cost of the residential fuel cell system. The proposed analysis methodology is based on the simulator including the efficiency models as well as the cost data for fuel cell components. The load control strategy is the key factor to decide the system efficiency and thus the cost analysis is performed when the fuel cell system is operated for several different load control logics. Additionally, annual efficiency of the system based on the seasonal load data is calculated since system efficiency is changeable according to the electric and heat demand change. As a result, the hybrid load control combined electricity oriented control and heat oriented control has the most economical operation.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.180-183
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• 2000

The Battery Energy Storage System(BESS) has lots of advantages such as load levelling, quick response emergency power(spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission construction. The economic feasibility requires justification from the customer side of meter to promoting the dissemination of BESS nationally. In this paper, we proposed the economic assessment model of customer owned Battery Energy Storage System(BESS) which is complemented and improved the existing model. The proposed model is applied to the typical customer type(light-industrial commercial, and residential) which are taken from the statistical analysis on the load profile survey of Korea Electric Power COmpany (KEPCO). The economic assessment performed for each customer type to justifying their economic feasibility of BESS installation from the economic measures such as payback period, overall benefits, ROI, and ROR. The results of this paper are useful to the customer investment decision making and the national energy policy & strategy.

• Journal of Power System Engineering
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• v.20 no.3
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• pp.5-10
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• 2016

The structure of the variable liquid column oscillator(VLCO) is analogous to that of the tuned liquid column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. VLCO is using the technology which absorbs high potential energy made by process of accelerated motions effect of air spring by installation of inner air chamber. So, the application of VLCO can improve the efficiency of energy than that of wave energy converters made in Pelamis Company. In this research, experiments were performed for the models which have two different liquid column sizes. In order to find out the biggest motion response, two major conditions are taken into account. Two conditions are to open(or close) the valves and to differentiate the height of the liquid column.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.95-101
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• 1996

In this paper, the steady 2-dimensional model for a long horizontal line with different end temperatures undergoing natural convection at very high Rayleigh number is proposed to numerically investigate the heat transfer and flow characteristics. The dimensionless governing equations are solved by using SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm which is developed using control volumes and staggered grids. The numerical results are verified by comparison with the operating PWR test data. The analysis focuses on the effects of variation of the heat transfer rates at the pipe surface, the thermal conductivities of the pipe material and the thickness of the pipe wall on the thermal stratification. The results show that the heat transfer rate at the pipe surface is the controlling parameter. A significant reduction and disappearance of thermal stratification phenomenon is observed at the Biot number of 5.0$\times$10$^{-2}$. The results also show that the increment of the thermal conductivity and thickness of the wall weakens the thermal stratification and somewhat reduces azimuthal temperature gradient in the pipe wall. Those effects are however minor, when compared with those due to the variation of the heat transfer rates at the surface of the pipe wall.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.545-553
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• 2012

Eco-efficiency considers both environmental impacts and economic values. It is a useful tool for communicating with stakeholders for business decision making. This study evaluated the eco-efficiency factor (EEF) for the energy network of a dyeing company that supplies surplus heat to a neighboring apartment during the night. This symbiosis network is one of the eco-industrial park (EIP) projects in Korea and aims to benefit local residents and the industrial complex by utilizing surplus heat. In this study, two categories were annualized. The first quantified environmental burden based on $CO_2$ emissions and quantified product value in terms of steam sales. The second used a variety of environmental factors, such as fossil fuel, water and waste, to quantify environmental burden and used steam sales to quantify value. The EEF of the symbiosis network was 1.6, using the global warming impact, and determined using the multiple variable, was 1.33. This study shows that the EEF depends on variable details of environmental burden but the values of this project were very high contrast to other business or EIP project.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.127-136
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• 2012

In this research, customized management performance index for small and medium enterprises in solar energy area was developed. To acquire management performance index, first Delphi technique is applied and secondly, AHP(Analytic Hierarchy Process) used to give weight to each main index and then final management performance index was achieved. By developing management performance index, top management could manage their company more efficiently.

• International Journal of Railway
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• v.6 no.3
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• pp.85-89
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• 2013

The purpose of this paper is investigating the effect and influence rates of utilizing thin walled energy absorption tubes for improving crashworthiness parameter by increasing energy absorption of the body in high speed railcars. In order to find this, a proper profile of available tubes is chosen and added to the structure of selected high speed train in Iranian railway network (Pardis Trainset) and then examined in the scenario of impact with other moving rolling stock. Because of the specific features of LS-DYNA 3D software at collision analysis, the dynamic simulation has been performed in LS-DYNA 3D. The results of the analysis clearly indicate the improvement of train crashworthiness as the energy absorption of structure increases more than 30 percent in comparison with the original body. This strategy delays and reduces the shock to the structure. The verification of the simulation is by using ECE R66 standard.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.8
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• pp.23-30
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• 2018

A necessity of increasing the energy efficiency of the buildings is rising due to global warming and high energy demands prices. Commissioning is an effective way to increase the energy efficiency of the building and reduce maintenance costs. In this study, a case study was conducted to derive the commissioning process of green building and propose management factors that can be used in domestic commissioning projects. The case was a university renovation project that received a LEED Glod certification and conducted the enhanced commissioning. The commissioning is divided into planning, design, construction, and post-construction phases. In the planning stage, commissioning company selection, commissioning goal setting, tasks and responsibilities for each subject are set. In the design phase, preparations are made for inspection and construction steps to prevent design errors. In the construction phase, problems are solved through periodic on-site inspections. In the post-construction phase, a final report with all the details of the commissioning will be created and future maintenance strategies will be proposed. Based on the findings of this study, it will be a basis for the management factors that can be used in the implementation of domestic commissioning projects.