• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.331-336
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• 2019

In this study, required properties and optimized procedure conditions for the pitch based soft carbon anode of lithium ion battery was investigated for improving the initial efficiency and rate performance. Each petroleum residue was thermally treated at 360, 370, and $410^{\circ}C$ for 3 hours to synthesis a pitch and the corresponding pitch shows the softening point of 86, 98, and $152^{\circ}C$, respectively. The elemental analysis and thermal characteristics of the pitch were investigated by EA analysis and TGA. It was noted that the low H/C and improved thermal stability were obtained with the high softening point. The obtained pitch was carbonized at $1,200^{\circ}C$ for 1 hour to produce a soft carbon based anode. As a result of investigating the crystal structure by XRD analysis, it was found that the crystallinity of soft carbon increased with increasing the softening point. It was considered that relatively higher boiling components and decreases in the evaporation component resulted the components participation for cyclization during the heat treatment process. The soft carbon based anode with an improved crystallinity shows the enhanced initial efficiency and rate performance. The mechanism of both improvements was also discusssed based on the developed crystal structure of soft carbon based anode materials.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.472-478
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• 2023

In this study, the acetaldehyde removal characteristics of activated carbon (AC) for air purifier filters were investigated using metal catalysts-impregnation and functional group-modification method. The AC with a high specific surface area(1700 m²/g) and micropores was prepared by KOH activation of coconut charcoal and the efficiency of catalyst and functional group immobilization was examined by varying the drying conditions within the pores after immersion. The physical properties of the prepared activated carbon were analyzed by BET, ICP, EA, and FT-IR, and the acetaldehyde adsorption performances were investigated using gas chromatography (GC) at various impregnation and modified conditions. As the concentration of impregnation solution increased, the amount of impregnated metal catalysts increased, while the specific surface area showed a decreasing trend. The adsorption tests of the metal catalyst-impregnated and functional group-modified activated carbons revealed that excellent adsorption performance in compositions MgO10@AC, CaO10@AC, EU10@AC, and H-U3N1@AC, respectively. The MgO10@AC, which showed the highest adsorption performance, had a breakthrough time of 533.8 minutes and adsorption capacity of 57.4 mg/g for acetaldehyde adsorption. It was found that the nano-sized MgO catalyst on the activated carbon improved the adsorption performance by interacting with carbonyl groups of acetaldehyde.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.121-122
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• 2008

Blue emitting materials have been explored by various researchers. However, blue-emitting materials with high luminous efficiency, good color purity, and thermal stability are still much desired. In this study, we synthesized a new blue luminescent material, $SnDP(HPB)_2$ which is low molecular compound and thermal stability. The PL spectrum of $SnDP(HPB)_2$ was observed blue at the wavelength of 447nm. The ionization potential(IP) and the electron affinity(EA) of $SnDP(HPB)_2$ was measured to be 6.7 eV and 3.0 eV, respectively. The fundamental structure of the OLED was ITO/NPB/$SnDP(HPB)_2/Alq_3$/LiF/Al. As a Result, we obtained to enhance the performance of blue OLED.

• KIEAE Journal
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• v.14 no.2
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• pp.21-28
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• 2014

This paper provides the up to date review of the shading effects on PV module performance and the associated detection algorithm related to the maximum power point tracking. It includes the brief explanations of the MMP variations due to the shading occurrence on the PV modules. Review of experimental and simulation studies highlighting the significant impacts of shading on PV efficiencies were presented. The literature indicates that even the partial shading of a single cell can greatly drop the entire module voltage and power efficiency. The MMP tracking approaches were also reviewed in this study. Both conventional and advanced soft computing methods such as ANN, FLC and EA were described for the proper tracking of MMP under shaded conditions. This paper would be the basic source and the comprehensive information associated with the shading effects and relevant MPP tracking technique.

• International Journal of Control, Automation, and Systems
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• v.1 no.2
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• pp.184-193
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• 2003

Biaffine Matrix Inequality (BMI) is known to provide the most general framework in control synthesis, but problems involving BMI's are very difficult to solve because nonconvex optimization should be solved. In the previous paper, we proposed a new solver for problems involving BMI's using Evolutionary Algorithms (EA). In this paper, we solve several control synthesis examples such as Reduced-order control, Simultaneous stabilization, Multi-objective control, $H_{\infty}$ optimal control, Maxed $H_2$ / $H_{\infty}$control design, and Robust $H_{\infty}$ control. Each of these problems is formulated as the standard BMI form, and solved by the proposed algorithm. The performance in each case is compared with those of conventional methods.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.59-65
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• 2023

This paper proposes an Extended and Adaptive Inverse Perspective Mapping (EA-IPM) model that can obtain an accurate bird's-eye view (BEV) from the forward-looking monocular camera on the sidewalk with various curves. While Inverse Perspective Mapping (IPM) is a good way to obtain ground information, conventional methods assume a fixed relationship between the camera and the ground. Due to the nature of the driving environment of the mobile robot, there are more walking environments with frequent motion changes than flat roads, which have a fatal effect on IPM results. Therefore, we have developed an extended IPM process to be applicable in IPM on sidewalks by adding a formula for complementary Y-derive processes and roll motions to the existing adaptive IPM model that is robust to pitch motions. To convince the performance of the proposed method, we evaluated our results on both synthetic and real road and sidewalk datasets.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.392-397
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• 2013

To fulfill the demands concerning energy efficiency for zero energy buildings, various technologies of architects and engineers are required. This study aims to estimate the thermal performance of heat source equipment in which part load characteristics are considered in an office building. Overestimation of heat source equipment was reviewed through literature survey, and heating and cooling loads depending on the capacity and division of the equipment were analyzed through a simulation program (DOE-2.1E). The conclusions gained from this study are as follows; 1) The more the division of equipment, the less the heating and cooling energy consumption. 2) When a large item of equipment is divided into two small items of equipment, the optimum application rate showed as 5:5 for chiller, and 7:3 for boiler, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.452-459
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• 2017

In recent years, to reduce self-weight of structural elements, the use of SCP (Steel Concrete Plate) instead of prestressed concrete is increasing. Because SCP has a complicated sectional shape and includes a large number of studs, the use of high-fluidity concrete is required. Therefore, in this study, to prevent the restrained shrinkage behavior by the stud, the effects of using an expansive agent (EA) and shrinkage reducing agent (SRA) were investigated, and the optimal mixture proportions to maximize the filling capacity were determined based on the fine aggregate ratio. The test results indicated that the combined use of EA and SRA exhibited the smallest shrinkage. The ratio of the crushed sand and washed sea sand was determined to be 5:5, and the proper fine aggregate ratio was found to be 55.6%, because when the ratio was too high, a decrease in strength and an increase in shrinkage strain were expected. The high-fluidity concrete effectively filled the large-sized SCP module.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.93-101
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• 2015

Zero energy building is a self sufficient building that minimizes energy consumption through passive elements such as insulation, high performance window system and installing of high efficiency HVAC system and uses renewable energy sources. The Korea Government has been strengthening the building energy efficiency standard and code for zero energy building. The building energy performance is determined by the performance of building envelope. Therefore it is important to optimize facade design such as insulation, window properties and shading, that affect the heating and cooling loads. In particular, shading devices are necessary to reduce the cooling load in summer season. Meanwhile, BIPV shading system functions as a renewable energy technology applied in solar control facade system to reduce cooling load and produce electricity simultaneously. Therefore, when installing the BIPV shading system, the length of shadings and angle that affect the electricity production must be considered. This study focused on the facade design applied with BIPV shading system for maximizing energy saving of the selected standard building. The impact of changing insulation on roof and walls, window properties and length of BIPV shading device on energy performance of the building were investigated. In conclusion, energy consumption and electricity production were analyzed based on building energy simulations using energyplus 8.1 building simulation program and jEPlus+EA optimization tool.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.423-436
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• 1996

Thermodynamic performance of eight zeotropic R-22 alternative refrigerant mixtures selected by AREP(R-22 Alternative Refrigerants Evaluation Program) and R-32/R-125/R-134a(23%/25%/52%), namely R-407C were evaluated by the "drop-in" simulation method. An existing air conditioner was selected and its design data were used for the simulation. "ARI Test A" air conditions were applied. The degree of vapor superheat at the compressor inlet fixed at $5^{\circ}C$ for all the mixtures. The results of the simulation were compared with those of R-22. COPs of all mixtures except for R-32/R-227ea(35%/65%) and R-32/R-125/R-134a(10%/70%/20%), were higher than that of R-22 by 2%~8%, while the capacities were all lower than that of R-22 by 13%~27%. COP of R-32/R-134a(40%/60%) was 2.4% higher but the capacity was 15% lower than those of R-22. In the case of R-32/R-134a(30%/70%), COP and capacity were 5.5% higher and 15% lower than those of R-22, respectively. Among the ternary mixtures, R-407C and R-32/R-125/R-134a(30%/10%/60%) showed the best performance. COP of R-407C was 2.4% higher than those of R-22 but the capacity was 15% lower.