• Composites Research
• /
• v.37 no.2
• /
• pp.108-114
• /
• 2024

Due to the continuously increasing global demand for electricity, the demand for high-voltage submarine cables is also increasing. One of the issues that need to be addressed for submarine cables is the high production cost and expensive laying costs. Submarine cables exposed to the marine environment encounter external forces such as wave and current, leading to issues such as cable damage due to external factors or high maintenance costs in the event of an accident. Therefore, we are preparing for the uncertainty of the submarine environment through many protective materials and protective equipment. In this study, we examined the bending performance of piggyback clamps (PBC) and strap, which are representative protective equipment, in response to the submarine environment through analytical methods. To examine the structural performance of PBC, the bending performance were assessed under the maximum bending moment criterion of 15 kN·m for the flexible protection tube. As a result, it was confirmed that the structural performance regarding the bending moment of both PBC and straps was ensured.

• Journal of Climate Change Research
• /
• v.1 no.2
• /
• pp.163-177
• /
• 2010

This study analyzes the economies of photovoltaic systems in an apartment complex of 1,185 households, in cases of feed-in tariff and subsidy for solar home program of the government. When including the revenue only from electricity sales, NPVs of subsidy and that of feed-in tariff are -560 million KRW and -87 million KRW respectively. With the avoided social cost included without the revenues from CERs, NPVs of subsidy and feed-in tariff are -556 million KRW and -84 million KRW respectively. With the revenues from CERs, NPV of subsidy is -526 million KRW and NPV of feed-in tariff is -54 million KRW. As results of sensitivity analysis based on the changes in capital costs and discount rates, while all scenarios with subsidy including the revenues from CERs are not commercially viable, all scenarios with feed-in tariff exclusive of the revenues from CERs are commercially viable when discount rate is less than 7.2% or capital cost is less than 6,840 thousand KRW/kW. In the cases that include the avoided social cost, while all scenarios with subsidy including the avoided social cost as well as the revenues from CERs are not commercially viable, all scenarios with feed-in tariff are commercially viable without the revenues from CERs when discount rate is less than 7.2% or capital cost is less than 6,856 thousand KRW/KW. The results indicate that the changes in discount rates do not influence the revenues from CERs, but the revenues from electricity sale. Considering that the number of apartment complex and the positive environmental and social benefits from PV system, government needs to promote its diffusion.

• KEPCO Journal on Electric Power and Energy
• /
• v.2 no.4
• /
• pp.577-582
• /
• 2016

This Study focused on the development of SMPS (Switching Mode Power Supply) to supply the constant votage and current nevertheless LED fluorescent Light generated the electric noise (with Harmonics) and Inrush current at instant time of turn-on and off. Recently, according to the Green policy in government, the LED fluorescent Lighter showed the rapidly increasing tend as indoor and outdoor Lighter. But, because of costs, LED fluorescent Light not considered and neglected the following items; power factor, efficiency, Harmonics and Inrush current. So, we are developed the SMPS about 3 key issues as follows: 1st, power factor and efficiency is 85%. 2nd, the switching noisy by harmonic is minimized. 3rd, the Inrush current at turn on and off time is reduced the minimum 0.3 A after $100{\mu}sec$ on turnon time. The proposed SMPS adjusted by LNK 409 driver (included the high frequency modulation function). Although, the developed SMPS maintained the about 85% of power factor and efficiency. but, the SMPS must be generated low heat by the variation of minute load current at switching timing. To improve the above weak point, the developed SMPS have the feedback monitoring circuit between input side and output side to maintain the power factor and efficiency. Also, we are studied the time-constant of control circuit to output the constant voltage and current nevertheless the load disturbance of LED lighting. The LED fluorescent Light of 46W is checked the above items.

• The Journal of the Korea Contents Association
• /
• v.15 no.6
• /
• pp.43-53
• /
• 2015

This study analyzes economic feasibility of the LED lighting system compare to the halogen. To evaluate economic feasibility of the LED devices, we analyzed the size of theater, current value of the lighting devices in kinds, annual cost and annual cost according to the surface in case of designing stage lighting system with LED using WEELS 2011. Also, to compare energy consumption, we analyzed consumption and amount of electric energy by the surface and the amount of CO2 emission. Data showed that annual cost of the LED devices are highly inexpensive than halogen and now the value is of great. However initial cost of the equipment 200% higher than halogen. Though LED devices are expensive in startup setting, the value of utilization factor is large and depreciation years of LED(30years) are longer than halogen(2years). Therefore, annual cost of LED can make up the minus. Consider the tendency of reducing price of LED devices, we can assume that annual cost of the LED will be lower than halogen devices. Further, in 3years the expense of LED and halogen is reversed.

• Korean Journal of Construction Engineering and Management
• /
• v.13 no.1
• /
• pp.140-147
• /
• 2012

Climate changes caused by fossil fuel energy usages have led to serious environmental damages and resource scarcity. Ever-increasing demand for energy causes harsh competition in international energy markets. Nuclear power, which once was regarded as a desirable clean energy, began to face public oppositions after the Japanese nuclear disaster in 2011. In this context, wind power is now considered to be an ever-more important recyclable energy source. Thus, this study intended to identify critical success factors for wind power construction projects. After a thorough literature review, two focus group interview sessions were conducted. A questionnaire-based survey, coupled with the two previous methods, resulted in the extraction of important factors for the success of wind power projects. Experts, including those working as constructors, designers, and owners, were paid a direct visit for the interview and survey. The critical success factors were categorized into feasibility study, right policies, equipment selection, and project financing issues. The proposed critical success factors are expected to be an effective guideline for future investors in wind powers.

• Journal of Internet of Things and Convergence
• /
• v.9 no.6
• /
• pp.93-98
• /
• 2023

In paddy rice farming, water management is a critical task. To suppress weed emergence during the early stages of growth, fields are deeply flooded, and after transplantation, the water level is reduced to promote rooting and stimulate stem generation. Later, water is drained to prevent the production of sterile tillers. The adequacy of water supply is influenced by various factors such as field location, irrigation channels, soil conditions, and weather, requiring farmers to frequently check water levels and control the ingress and egress of water. This effort increases if the fields are scattered in remote locations. Automated irrigation systems have been considered to reduce labor and improve productivity. However, the net income from rice production in 2022 was about KRW 320,000/10a on average, making it financially unfeasible to implement high-cost devices or construct new infrastructure. This study focused on developing an IoT-Based irrigation valve that can be easily integrated into existing agricultural infrastructure without additional construction. The research was carried out in three main areas: Firstly, an irrigation valve was designed for quick and easy installation on existing agricultural pipes. Secondly, a power circuit was developed to connect a low-power Cat M1 communication modem with an Arduino Nano board for remote operation. Thirdly, a cloud-based platform was used to set up a server and database environment and create a web interface that users can easily access.