• KIEAE Journal
• /
• v.14 no.3
• /
• pp.5-13
• /
• 2014

This paper introduces emergy(spelled with "m") that is a new environmental indicator in architecture, aiming to clarify conflicting claims of building design components in the process of energy-retrofit. Much of design practitioners' attention on low energy use in operational phases, may simply shift the lowered environmental impact within the building boundary to large consumption of energy in another area. Specifically, building energy reduction strategies without a holistic view starting from natural formation, may lead to the depletion of non-renewable geobiological sources (e.g. minerals, fossil fuels, etc.), which leaves a building with an isolated energy-efficient object. Therefore, to overcome the narrow outlook, this research discusses the total ecological impact of a building which embraces all process energy as well as environmental cost represented by emergy. A case study has been conducted to explore emergy-driven design work. In comparison with operational energy-driven scenarios, the results elucidate how energy and emergy-oriented decision-making bring about different design results, and quantify building components' emergy contribution in the end. An average-size ($101.9m^2$) single family house located in South Korea was sampled as a benchmark case, and the analysis of energy and material use was conducted for establishment of the baseline. Adoption of the small building is effective for the goal of study since this research intends to measure environmental impact according to variation of passive design elements (windows size, building orientation, wall materials) with new metric (emergy) regardless of mechanical systems. Performance simulations of operational energy were developed and analyzed separately from the calculation of emergy magnitudes in building construction, and then the total emergy demand of each proposed design was evaluated. Emergy synthesis results verify that the least operational energy scenario requires greater investment in indirect energy in construction, which clearly reveals that efficiency gains are likely to be overwhelmed by increment of material flows. This result places importance on consideration of indirect energy use underscoring necessity of emergy evaluation towards the environment-friendly building in broader sense.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.660-664
• /
• 2014

A diesel forklift truck under 3-ton class has disadvantages in the vibration transmission path. Because the weight ratio of body structure to powertrain which is source of excitation force is lower th an a mid-class forklift. In addition, the torsional and bending vibration mode frequencies of body structure are within the engine excitation frequency range, then high idle vibration generated by resonance. In this paper vehicle body structure design and optimization technique considering idle vibration reduction are presented. Design sensitivity analysis is applied to search the sensitive of design parameters in body structure. The design parameters such as thickness and pillar cross section were optimized to increase the torsional and bending vibration mode frequencies.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.04a
• /
• pp.166-171
• /
• 2008

We cannot imagine any more the environment and energy problems are separated from our lives. The various attempts to solve these problems are made all over the world. In this study it was performed to analyze a different heating and cooling load depending on the earth-sheltering method and kind of soils by using TRNSYS 16 as the first step to establish the design guidelines for earth-sheltered architecture, one of the eco-friendly and low energy consuming building types. After performing this simulation, we found the result like this. It is the most lowest load in case of all of walls and roof being earth-sheltered. But considering of the load reduction rate, the effect of earth-sheltering the exterior vertical wall is more efficient for load reduction than the one of earth-sheltering a roof. And we got a lower thermal load in case of a lower heat conductivity of soil. Afterwards we will conduct a further study for boundary condition at earth-sheltered surface and the simulation analysis about the sensitivity variables. The final goal of this study is preparing the design guidelines for earth-sheltered architecture. so we will contribute to building energy saving.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.11
• /
• pp.1535-1540
• /
• 2013

In this paper, the Radial Magnetic Force(RMF) and cogging torque which cause vibration and noise in IPM type BLDC motor were analyzed. The cogging torque and RMF cause electromagnetic vibration. So, a notch was installed for the equilibrium of RMF and cogging torque reduction. The notch was analyzed by using a Fourier Series for the energy distribution of the air-gap. The equilibrium of RMF and the reduction of cogging torque were performed by a Design Of Experiment(DOE) with the notch. Also, operating characteristics and efficiency were analyzed and compared.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.6
• /
• pp.1988-1994
• /
• 2014

In a single-phase grid-connected power system consisting of a DC/DC converter and a DC/AC converter, the current drawn from renewable energy sources has a tendency to be pulsated and contains second-order frequency ripple components, which results in several drawback such as a power harvesting loss and a shortening of the energy source's life. This paper presents a new second-order harmonic current reduction scheme with a fast dc-link voltage loop for two-stage dc-dc-ac grid connected systems. In the frequency domain, an adequate control design is performed based on the small signal transfer function of a two-stage dc-dc-ac converter. To verify the effectiveness of proposed control algorithm, a 1 kW hardware prototype has been built and experimental results are presented.

• Journal of the Korean Solar Energy Society
• /
• v.38 no.2
• /
• pp.1-13
• /
• 2018

This paper deals with the NREL (National Renewable Energy Laboratory) 5-MW reference wind turbine. The controller which include MPPT (Maximum power point tracking) control algorithm and tower load reduction control algorithm was designed by MATLAB Simulink. This paper propose a tower damper algorithm to improve the existing tower damper algorithm. To improve the existing tower damper algorithm, proposed tower damper algorithm were applied the thrust sensitivity scheduling and PI control method. The thrust sensitivity scheduling was calculated by thrust force formula which include thrust coefficient table. Power and Tower root moment DEL (Damage Equivalent Load) was set as a performance index to verify the load reduction algorithm. The simulation were performed 600 seconds under the wind conditions of the NTM (Normal Turbulence Model), TI (Turbulence Intensity)16% and 12~25m/s average wind speed. The effect of the proposed tower damper algorithm is confirmed through PSD (Power Spectral Density). The proposed tower damper algorithm reduces the fore-aft moment DEL of the tower up to 6% than the existing tower damper algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.12
• /
• pp.2157-2164
• /
• 2010

Microgrid is generally defined as cluster of small distributed generators, energy storages and loads. Through monitoring and coordinated control, microgrid can provide various benefits such as reduction of energy cost, peak shaving and power quality improvement. In design stage of microgrid, system dynamic simulation is necessary for optimizing of sizing and siting of DER(distributed energy resources). As number of the system components increases, simulation time will be longer. This problem can restrict optimal design. So we used simplified modeling on energy sources and average switching model on power converters to reduce simulation time. The effectiveness of this method is verified by applying to prototype microgrid system, which is consist of photovoltaic, wind power, diesel engine generators, battery energy storage system and loads installed in laboratory. Simulation by Matlab/Simulink and measurements on prototype microgrid show that the proposed method can reduce simulation time not sacrificing dynamic characteristics.

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.2
• /
• pp.223-232
• /
• 2013

In this study, carbon emissions and energy consumption were evaluated to establish a design strategy which has low energy consumption and carbon emission production, by using life cycle energy (LCE) and life cycle $CO_2(LCCO_2)$ calculation methods in life cycle management(LCM) tools. After improvement design projects, the energy consumption and $CO_2$ emission were calculated and compared in three sewage treatment plants (STPs), which are A STP, B STP, and C STP. The reduction of carbon emissions was 28,020.1 ton $CO_{2-}e/yr$, 37,399.6 ton $CO_{2-}e/yr$ and 8,788.3 ton $CO_{2-}e/yr$, respectively. Production of energy was 792 TOE/yr, 1,235 TOE/yr and 1,023 TOE/yr, respectively. As a result, the estimation of energy and energy self-sufficiency was 5.1 %, 14.5 % and 23.5 %, respectively. The result of this study shows the LCM can be contributed to establish strategy for energy and carbon emission reduction in sewage treatment plants.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.1
• /
• pp.134-137
• /
• 2010

An LED sensor luminaire for visual function improvement necessitates the control algorithm for light level adjustment and the appropriate lens design. The control algorithm adapts to surround lighting condition, and thus has the advantages of energy saving and glare reduction. The multi-cell lens design improves color temperature uniformity and spatial light distribution of the luminaire. Experimental and simulated results show that this approach contributes noticeably to energy saving and color temperature uniformity of the LED sensor luminaire.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.2
• /
• pp.58-67
• /
• 2023

While extensive research is being conducted to reduce greenhouse gases in industrial fields, the International Maritime Organization (IMO) has implemented regulations to actively reduce CO₂ emissions from ships, such as energy efficiency design index (EEDI), energy efficiency existing ship index (EEXI), energy efficiency operational indicator (EEOI), and carbon intensity indicator (CII). These regulations play an important role for the design and operation of ships. However, the calculation of the index and indicator might be complex depending on the types and size of the ship. Here, to calculate the EEDI of two target vessels, first, the ships were set as Deadweight (DWT) 50K container and 300K very large crude-oil carrier (VLCC) considering the type and size of those ships along with the engine types and power. Equations and parameters from the marine pollution treaty (MARPOL) Annex VI, IMO marine environment protection committee (MEPC) resolution were used to estimate the EEDI and their changes. Technical measures were subsequently applied to satisfy the IMO regulations, such as reducing speed, energy saving devices (ESD), and onboard CO₂ capture system. Process simulation model using Aspen Plus v10 was developed for the onboard CO₂ capture system. The obtained results suggested that the fuel change from Marine diesel oil (MDO) to liquefied natural gas (LNG) was the most effective way to reduce EEDI, considering the limited supply of the alternative clean fuels. Decreasing ship speed was the next effective option to meet the regulation until Phase 4. In case of container, the attained EEDI while converting fuel from Diesel oil (DO) to LNG was reduced by 27.35%. With speed reduction, the EEDI was improved by 21.76% of the EEDI based on DO. Pertaining to VLCC, 27.31% and 22.10% improvements were observed, which were comparable to those for the container. However, for both vessels, additional measure is required to meet Phase 5, demanding the reduction of 70%. Therefore, onboard CO₂ capture system was designed for both KCS (Korea Research Institute of Ships & Ocean Engineering (KRISO) container ship) and KVLCC2 (KRISO VLCC) to meet the Phase 5 standard in the process simulation. The absorber column was designed with a diameter of 1.2-3.5 m and height of 11.3 m. The stripper column was 0.6-1.5 m in diameter and 8.8-9.6 m in height. The obtained results suggested that a combination of ESD, speed reduction, and fuel change was effective for reducing the EEDI; and onboard CO₂ capture system may be required for Phase 5.