• Journal of the Korean Institute of Gas
• /
• v.7 no.4 s.21
• /
• pp.7-13
• /
• 2003

This study was carried out to optimize premixed burner and heat exchanger of the condensing gas boiler which can save energy by utilizing latent heat of combustion gas and reduce pollutant in exhaust gas. The heat exchanger of the gas boiler was composed of three parts, which were an upper, lower, and coil heat exchanger. The upper heat exchanger was placed outside of the premixed burner and a lower heat exchanger was located under the upper heat exchanger. And, coil heat exchanger rounded the outer surface of an upper and lower heat exchanger. The boiler designed by this research reaches turn-down ratio 4:1 in the domain of equivalence ratio 0.75${\~}$0.8 and thermal efficiency of $97\%$. Emission of NOx and CO concentration was under 20ppm and 140ppm at equivalence ratio 0.8. When diameter of the burner is replaced from 60mm to 50mm, emission of CO was reduced about 50ppm remarkably.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.4
• /
• pp.157-166
• /
• 1994

Recently. the excessive diesel engine torsional excitation of typical energy saving ships has resulted in severe damages of the propeller shaft. Up to now the design and torsional vibration analysis of the marine diesel shafting system has been performed on the assumption that excitations are deterministic. But a diesel engine excitation varies randomly from cylinder to cylinder and from cycle to cycle, due to the imperfect operation of the engine components due to engine misfiring. consequently, a more rational analysis method for the propulsion shafting torsional vibration is required. In this paper probabilistic analysis method of the marine diesel engine shafting system under torsional vibration is presented. First a response surface representing maximum shear stresses in a shafting system is built. Then Monte Carlo simulation with subsequent approximation of the results by one of Pearson's curves, is performed. Some numerical results based on the proposed method are compared with t도 some numerical data available. They show acceptable agreements with the data.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.4
• /
• pp.55-63
• /
• 1995

This paper describes the procedure to analyze the performance of the end-plated propeller(EPP) by a boundary integral method. The screw blade(SB) and end-plate(EP) are represented by a set of quadrilateral panels, where the source and normal dipole of uniform strength are distributed. The perturbation velocity potential, being the only unknown via the potential-based formulation, is determined by satisfying the flow tangency condition on the blade and the end-plate at the same time. The Kutta condition is satisfied through an iterative process by requiring the null pressure jump across the upper and lower sides of the trailing edges of both the SH and the EP. Sample calculations indicate that the EP increases the loading near the tip of the SB while spreading the trailing vortices along the trailing edge of the EP, thus avoiding the strong tip-vortex formation. Predicted performance of the EPP shows good correlations with the experimental results. The method is therefore considered applicable in designing and analyzing the EPP which may be an alternative for energy-saving propulsive devices.

• Journal of the Korea Convergence Society
• /
• v.12 no.7
• /
• pp.159-167
• /
• 2021

The increasingly severe environmental problems such as resource depletion and ecological damage, and consumers' concern for sustainable fashion, make the fashion industry chain develop towards green energy saving. The purpose of this study is to explore the attitude and consumption psychology of specific groups towards sustainable fashion consumption, as well as their specific views and attitudes towards recycled textiles or fabrics for re-manufacturing clothing. This paper attempts to understand how the characteristics of recycled clothing affect consumer. Based on the review of relevant literature, a series of determinants affecting consumer behavior is determined, and the characteristics of recycled products, such as expression value and social value, are determined. An online questionnaire was designed based on this conceptual framework, and 226 valid, complete answers were received. The results show that the emphasis on social value and environmental protection consciousness can effectively affect consumers' decision-making. These findings were helpful to the research of whole green environmental protection and ecological clothing recycling industry system, promote the sustainable development of the clothing industry.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.37 no.5
• /
• pp.1-12
• /
• 2009

The purpose of this research was to propose policy directions for the design and construction of nature-friendly park facilities (PF) in national parks. In order to do that, nature-friendliness evaluation indicators(NEIs) used in green building rating systems and related articles were reviewed. After the initial literature review was complete, NEIs for park facilities based on location, design, construction, operation, and management sectors were developed. Data was obtained through a questionnaire completed by 79 managers at 19 national parks in Korea in 2008. The answers were analyzed using descriptive statistical methods, a t-test, a multi-dimensional analysis, and a factor analysis. This research found that: 1) The results indicated that based on relative weight calculation, the location condition was evaluated as the most important; 2) The evaluation results regarding the degree of nature-friendliness of park facilities showed that location condition was ranked higher than design and construction--in addition, the evaluated values of indicators related to energy efficiency were ranked the lowest; 3) the level of nature-friendliness of shelter was given the highest level, but resting facility was the lowest level; 4) Overall, park facilities at Mt. Seorak, Mt. Odae, and Taean Coast national parks showed high levels of nature-friendliness. But park facilities at Mt. Gyeongju and Mt. Songni national parks showed low levels of nature-friendliness. The results of this research shall contribute to the establishment of tailor-made management policies, the development of detailed guidelines for increased energy efficiency and visitor satisfaction, and the preservation of ecosystems and natural resources in Korea's national parks.

• Journal of Navigation and Port Research
• /
• v.46 no.6
• /
• pp.483-490
• /
• 2022

Floating LiDAR is a system that provides a new paradigm for wind condition observation, which is essential when creating an offshore wind farm. As it can save time and money, minimize environmental impact, and even reduce backlash from local communities, it is emerging as the industry standard. However, the design and verification of a stable platform is very important, as disturbance factors caused by fluctuations of the buoy affect the reliability of observation data. In Korea, due to the nation's late entry into the technology, a number of foreign equipment manufacturers are dominating the domestic market. The west coast of Korea is a shallow sea environment with a very large tidal difference, so strong currents repeatedly appear depending on the region, and waves of strong energy that differ by season are formed. This paper conducted a study examining buoys suitable for LiDAR operation in the waters of Korea, which have such complex environmental characteristics. In this paper, we will introduce examples of optimized design and verification of ship-type buoys, which were applied first, and derive important concepts that will serve as the basis for the development of various platforms in the future.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.4
• /
• pp.41-50
• /
• 2017

The design of proper agitation system is requisite in biological waste treatment and energy generation plant, which is affected by viscosity, impeller types, and power consumption. In the present work, hydrogen fermentation of food waste was conducted at various operational pHs (4.5~6.5) and substrate concentrations (10~50 g Carbo. COD/L), and the viscosity of fermented broth was analyzed. The $H_2$ yield significantly varied from 0.51 to $1.77mol\;H_2/mol\;hexose_{added}$ depending on the pH value, where the highest performance was achieved at pH 5.5. The viscosity gradually dropped with shear rate increase, indicating a shear thinning property. With the disintegration of carbohydrate, the viscosity dropped after fermentation, but it did not change depending on the operational pH. At the same pH level, the $H_2$ yield was not affected much, ranging $1.40{\sim}1.86mol\;H_2/mol\;hexose_{added}$ at 10~50 g Carbo. COD/L. The zero viscosity and infinite viscosity of fermented broth increased with substrate concentrations, from 10.4 to $346.2mPa{\cdot}s$, and from 1.7 to $5.3mPa{\cdot}s$, respectively. There was little difference in the viscosity value of fermented broth at 10 and 20 g Carbo. COD/L. As a result of designing the agitation intensity based on the experimental results, it is expected that the agitation intensity can be reduced during hydrogen fermentation. The initial and final agitation intensity of 30 g Carbo. COD/L in hydrogen fermentation were 26.0 and 10.0 rpm, respectively. As fermentation went on, the viscosity gradually decreased, indicating that the power consumption for agitation of food waste can be reduced.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.45 no.3
• /
• pp.47-57
• /
• 2008

Recently, energy-efficient NAND Flash memory of large volume is favored as next-generation storage for sensor nodes. So far, most sensor node file systems are based on NOR flash and few file systems are applicable to large NAND flash memory. Although it is required to develop new file systems taking account of the features of NAND flash memory, it is difficult to develop them mainly due to the limit of SRAM memory on sensor nodes. Sensor nodes support SRAM of $4{\sim}10$ KBytes only. In this paper, we designed and implemented a novel file system to support data-centric applications. To do this, we added EEPROM of 1 KBytes to store persistent file description data efficiently and devised a simple wear-leveling method. This reduces the number of page updates, resulting in reduction in energy use and increase in lifetime of sensor nodes.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.3
• /
• pp.343-359
• /
• 2017

Many researches and policies have been carried out for saving energy in buildings. However, there are a few studies of thermal characteristics of wood-based materials that have been widely used as structural materials and finishing materials in buildings. In this study, thermal bridging areas were found to investigate thermal performance of residential building using non wood-based materials and wood-based materials. And heat transfer analysis of 16 case studies according to composition of structural materials and finishing materials was conducted. Also in this experiment, Physibel Trisco was used as the heat transfer analysis simulation tool, which conforms to the calculation method of ISO 10211. Analytical modeling was also carried out according to the ISO 10211, and the boundary temperature conditions were set at room temperature $20^{\circ}C$ and outdoor temperature $-11.3^{\circ}C$ (Seoul standard) according to the energy saving design standard in South Korea. Applied structures are classified according to the cases of concrete structure with non wood-based finishing materials, concrete structure with wood-based finishing materials and wood structure. Analyzed building elements were divided into a wall, a roof, an interlayer floor and a bottom floor. As a result, it can be confirmed that the thermal bridge of the concrete structure and wood structure were caused by the geometrical and material causes. In addition, the structural thermal bridge was caused in the discontinuity of the insulation in the concrete structure. Also it was confirmed that the linear heat transfer coefficient of the wall decreases when the wood-based materials are applied to the concrete structure.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.11
• /
• pp.1345-1352
• /
• 2012

This paper aims to evaluate the low-velocity impact responses and mechanical properties of balsa-wood and urethane-foam core materials and their sandwich panels, which are applied as the impact limiter of a nuclear spent fuel shipping cask. For the urethane-foam core, which is isotropic, tensile, compressive, and shear mechanical tests were conducted. For the balsa-wood core, which is orthotropic and shows different material properties in different orthogonal directions, nine mechanical properties were determined. The impact test specimens for the core material and their sandwich panel were subjected to low-velocity impact loads using an instrumented testing machine at impact energy levels of 1, 3, and 5 J. The experimental results showed that both the urethane-foam and the balsa-wood core except in the growth direction (z-direction) had a similar impact response for the energy absorbing capacity, contact force, and indentation. Furthermore, it was found that the urethane-foam core was suitable as an impact limiter material owing to its resistance to fire and low cost, and the balsa-wood core could also be strongly considered as an impact limiter material for a lightweight nuclear spent fuel shipping cask.