• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.10
• /
• pp.655-660
• /
• 2018

Internal combustion generation (ICG) is used to supply power to islands due to geographical characteristics, but there are some problems, such as considerable operating cost, salt pollution, and environmental pollution. For these islands, KEPCO pays a significant amount of operating deficit each year, especially for the fuel and servicing costs, which account for a large portion of this deficit. Integrated ICG (IICG) through an offshore cable between near islands is being considered to decrease servicing costs. Distributed generation (DG) is also being introduced on the islands because of the demand for a low-carbon society. In hybrid internal combustion generation (HICG), DG is introduced into IICG, which can be applied because the DG output is insufficient due to environmental characteristics, and the IICG is used as an auxiliary power source. Therefore, this paper proposes an algorithm to estimate the optimal DG capacity that can be introduced in accordance with the KEPCO operating deficit in the HICG. According to simulations, the optimal DG capacity depends on the fuel cost and load capacity. The validity of the proposed algorithm was confirmed for multiple islands with different peak loads.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.2
• /
• pp.223-229
• /
• 2023

Seawater batteries are next-generation secondary batteries that use seawater as a cathode. They utilize marine resources to provide competitive prices, high eco-friendliness, and a structure suitable for marine applications. Based on these advantages, pouch types and prismatic types have been studied and developed assuming natural seawater exposure. However, because of the electrical characteristics of the secondary battery, its capacity and internal resistance vary depending on the use environment. These characteristics are not only utilized for predicting the life of a battery but also have a direct effect on the capacity and power suitable for a specific situation. Therefore, the internal resistance was analyzed in this study by measuring the capacity depending on the seawater battery use environment and the state-of-charge-open-circuit-voltage measurement method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.782-791
• /
• 2009

This study was carried out the laboratory tests and field plate load test in order to evaluate the reinforcement effect of geocell for road construction. The geocell-reinforced subgrade shows the increment of cohesion and friction angle with comprison of non-reinforced subgrade. In addition, the field plate load test was performed on the geocell-reinforced subgrade to estimate the bearing capacity of soil. The direct shear test was conducted with utilizing a large-scale shear box to evaluate the internal soil friction angle with geocell reinforcement. The number of cells in the geocell system is varied to investigate the effect of soil reinforcement. The theoretical bearing capacity of subgrade soil with and without geocell reinforcement was estimated by using the soil internal friction angle. The field plate load tests were also conducted to estimate the bearing capacity with geocell reinforcement. It is found out that the bearing capacity of geocell-reinforced subgrade gives 2 times higher value than that of unreinforced subgrade soil. In the future, the reinforcement effect of the geocell rigidity and load-balancing effect of the geocells should be evaluated.

• The Journal of Internal Korean Medicine
• /
• v.34 no.1
• /
• pp.100-111
• /
• 2013

Objectives : This study investigated the impact of Caesalpinia sappan L. on oxidative damage and inflammatory relevant factor in RAW 264.7 cells and human umbilical vein endothelial cells (HUVEC). Methods : We determined whether fractionated EtOH extracts of Caesalpinia sappan L. (CSL) inhibit free radical generation such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), reactive oxygen species (ROS) and nitric oxide (NO) and pro-inflammatory cytokines in lipopolysaccharide (LPS)-treated RAW 264.7 cells and HUVEC. Result : 1. DPPH removal capacity was increased by CSL. 2. LPS-induced ROS, and NO inhibitory capacity were increased by CSL. 3. LPS-induced cell death of Raw 264.7 cells was decreased by CSL. 4. The amount of cytokine generation in Raw 264.7 cell was decreased significantly by CSL. 5. The amount of cytokine generation in HUVEC was decreased significantly by CSL. Conclusions : These results suggest that CSL supplement may attenuate oxidative stress by elevated antioxidative processes, and suppress inflammatory mediator activation.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.119-122
• /
• 2009

The gravel compaction pile method has been used as a soft foundation improvement method because bearing capacity and discharge capacity is excellent. But the discharge capacity decreased when the clogging was generated because the clay penetrate into a void of gravel compaction pile. Accordingly, the purpose of this study is to reduce the clogging generation in gravel compaction pile constructing in the soft ground and take a step to minimize a void of gravel compaction pile. And the proper mixing ratio was determined with the large scale direct shear test performed to get strength and permeability with mixing ratio of crushed stone and sand(100:0, 90:10, 85:15, 80:20, 75:25). As a result of the test, it was showed that internal friction angle was the highest at 85:15 mixing ratio of crushed stone and sand and we can make sure a tendency of internal friction angle's decrease when the mixing ratio of crushed stone and sand passed 15%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.67-70
• /
• 2008

This paper deals with the effect of radial parameters in cogging process such as reduction in height (Rh) and rotational angle ($\theta$) of a billet on a void closure for large forged products. Usually closing and consolidation of internal void defects in a ingot is a vital matter when utilized as large forged products, using a press with limited capacity and the sizes of the ingots becoming larger. Consequently, it is important to develop cogging process for improvement of internal soundness without a void defect and cost reduction by solid forging alone with limited press capacity. For experiments of cogging process, hydraulic press with a capacity of 800 ton was used together with a small manipulator which was made for rotation and overlapping of a billet. Size of a void was categorized into two types; $\emptyset$ 6.0 mm and $\emptyset$ 9.0 mm to investigate the change of closing and consolidation of void defects existed in the large ingot during the cogging process. Also open void and closed void in the ingot were tackled to show the differentiation of closing process of internal voids with respect to void sizes. In this paper systematic configuration for closing process of void defects were expressed based on this experiment results in the cogging process.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2085-2090
• /
• 2007

This paper describes the possible way to improve the capacity, the efficiency and the pressure drop of $CO_2$ system. It is considered the use of an internal heat exchanger (IHX) to improve the performance of the $CO_2$ system. Experiment was performed by changing a tube shape, a tube number and a tube length of IHX to investigate the performance of IHX for $CO_2$ system. The focus of the present study is to obtain the concept on IHX optimal design. Experimental results show that design parameters are closely related with the capacity and the pressure drop of $CO_2$ system. In the transcritical $CO_2$ cycle, the system performance is very sensitive to the IHX design. System performance on operation condition and shape of IHX is also introduced.

• Journal of the Korean Home Economics Association
• /
• v.46 no.5
• /
• pp.87-96
• /
• 2008

The purpose of this study was to establish which factors were considered when fashion companies discussed the intention of employing the internet in various capacities. A total of 228 candidates were surveyed between 17-11-07 and 17-01-08. The collected data was used to conduct various descriptive and comparative analyses. Firstly, environmental factors considered important were internal pressure, external pressure and uncertainty of the market. Organizational factors considered important were support of the chief executive officer, capacity of the organization and future directivity. Profit factors considered important were elevation of the business, customer relationship management, advantage of the internet and reduction of expenses. Prohibitive factors considered important were miscellaneous expenses, secession of the customer, internal opposition of the organization and convertible expenses. Secondly, fashion companies regarded internal pressure, external pressure, support of the chief executive officer, capacity of the organization, future directivity, elevation of the business, customer relationship management, advantage of the internet and miscellaneous expenses as important when discussing the introduction of the internet.

• Tuberculosis and Respiratory Diseases
• /
• v.78 no.3
• /
• pp.190-195
• /
• 2015

Background: Although organizing pneumonia (OP) responds well to corticosteroid therapy, relapse is common during dose reduction or follow-up. Predictors of relapse in OP patients remain to be established. The aim of the present study was to identify factors related to relapse in OP patients. Methods: This study was retrospectively performed in a tertiary referral center. Of 66 OP patients who were improved with or without treatment, 20 (30%) experienced relapse. The clinical and radiologic parameters in the relapse patient group (n=20) were compared to that in the non-relapse group (n=46). Results: Multivariate analysis demonstrated that percent predicted forced vital capacity (FVC), $PaO_2/FiO_2$, and serum protein level were significant predictors of relapse in OP patients (odds ratio [OR], 0.82; 95% confidence interval [CI], 0.70-0.97; p=0.018; OR, 1.02; 95% CI, 1.00-1.04; p=0.042; and OR, 0.06; 95% CI, 0.01-0.87; p=0.039, respectively). Conclusion: This study shows that FVC, $PaO_2/FiO_2$ and serum protein level at presentation can significantly predict relapse in OP patients.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.4
• /
• pp.105-117
• /
• 2010

The topographical depressions in urban areas, the lack in drainage capability, sewage backward flow, road drainage, etc. cause internal inundation, and the increase in rainfall resulting from recent climate change, the rapid urbanization accompanied by economic development and population growth, and the increase in an impervious area in urban areas deteriorate the risk of internal inundation in the urban areas. In this study, the vulnerability of internal inundation in urban areas is analyzed and SWMM model is applied into Oncheoncheon watershed, which represents urban river of Busan, as a target basin. Based on the results, the representative storm sewers in individual sub-catchments is selected and the risk of vulnerability to internal inundation due to rainfall in urban streams is analyzed. In order to analyze the risk and vulnerability of internal inundation, capacity is applied as an index indicating the volume of a storm sewer in the SWMM model, and the risk of internal inundation is into 4 steps. For the analysis on the risk of internal inundation, simulation results by using a SMMM model are compared with the actual inundation areas resulting from localized heavy rain on July 7, 2009 at Busan and comparison results are analyzed to prove the validity of the designed model. Accordingly, probabilistic rainfall at Busan was input to the model for each frequency (10, 20, 50, 100 years) and duration (6, 12, 18, 24hr) at Busan. In this study, it suggests that the findings can be used to preliminarily alarm the possibility of internal inundation and selecting the vulnerable zones in urban areas.