• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.72-72
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• 2012

Lithium rechargeable batteries have been widely used as key power sources for portable devices for the last couple of decades. Their high energy density and power have allowed the proliferation of ever more complex portable devices such as cellular phones, laptops and PDA's. For larger scale applications, such as batteries in plug-in hybrid electric vehicles (PHEV) or power tools, higher standards of the battery, especially in term of the rate (power) capability and energy density, are required. In PHEV, the materials in the rechargeable battery must be able to charge and discharge (power capability) with sufficient speed to take advantage of regenerative braking and give the desirable power to accelerate the car. The driving mileage of the electric car is simply a function of the energy density of the batteries. Since the successful launch of recent Ni-MH (Nickel Metal Hydride)-based HEVs (Hybrid Electric Vehicles) in the market, there has been intense demand for the high power-capable Li battery with higher energy density and reduced cost to make HEV vehicles more efficient and reduce emissions. However, current Li rechargeable battery technology has to improve significantly to meet the requirements for HEV applications not to mention PHEV. In an effort to design and develop an advanced electrode material with high power and energy for Li rechargeable batteries, we approached to this in two different length scales - Atomic and Nano engineering of materials. In the atomic design of electrode materials, we have combined theoretical investigation using ab initio calculations with experimental realization. Based on fundamental understanding on Li diffusion, polaronic conduction, operating potential, electronic structure and atomic bonding nature of electrode materials by theoretical calculations, we could identify and define the problems of existing electrode materials, suggest possible strategy and experimentally improve the electrochemical property. This approach often leads to a design of completely new compounds with new crystal structures. In this seminar, I will talk about two examples of electrode material study under this approach; $LiNi_{0.5}Mn_{0.5}O_2$ based layered materials and olivine based multi-component systems. In the other scale of approach; nano engineering; the morphology of electrode materials are controlled in nano scales to explore new electrochemical properties arising from the limited length scales and nano scale electrode architecture. Power, energy and cycle stability are demonstrated to be sensitively affected by electrode architecture in nano scales. This part of story will be only given summarized in the talk.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.26-33
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• 2017

The objective of this study was to evaluate the characteristic of adsorption by using a meso-porous adsorbent (MPA), and investigate the removal efficiency of geosmin which taste and odor causing compounds in drinking water supplies through batch test. The results for the adsorption isotherm was analyzed by using the Langmuir equation and Freundlich equation, generally being applied. And the study showed that the both Langmuir and Freundlich equation explains the results better. Both of pseudo-first-order model and pseudo-second-order model were respectively applied for evaluation of kinetic sorption property of geosmin onto MPA. The adsorption experiment results using MPA showed that maximum adsorption capacity of MPA was lower 7 times than that of GAC, and adsorption rate of MPA was faster 11 times than that of GAC, on the basis of pseudo-first-order model. Therefore, it was determined that MPA was effectively able to remove geosmin in drinking water supplies in short EBCT condition, but regeneration cycle in MAP process was shorter than that in conventional process.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.69-76
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• 2007

As amount of waste matter rapidly increases with fast growth of cities and industry, how to dispose them has arisen as an important problem. Current policy of the government on disposal of waste is repressing generation of waste itself and in case of already generated waste, resource cycle waste management system that recycles waste after proper environmental process is getting established. Therefore recycling of waste and industrial by-products is rising hugely. One of largely wasted matters is waste gypsum, which was categorized as designated waste but changed to general since 1994. Due to disposal cost and lack of impurities removal technology, recycling of it was quite low. However, as impurities removal technology using semi-dried desulfurization process is developed lately, study on recycling of waste gypsum is going on lively. This study examines possibility of utilizing waste gypsum as alternative for concrete cement and analyzed attributes of waste gypsum before and after ball mill process to find out proper alternation ratio, and conducted strength and property tests on concrete subject whose percentage of cement use is substituted with 0, 5.0, 7.5, 10.0 and 12.5% of waste gypsum.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.8
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• pp.997-1004
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• 2006

This study was performed to investigate the storage properties of emulsion-type sausage added with Glycyrrhiza uralensis and Curcula longa hot water extracts (GCHE) extracted at $10^{\circ}C$ for 35 days. The TBARS values of sausages containing 1.0 and 5.0% GCHE were lower than that of control. The bacterial count and VBN contents of all the samples were significantly increased during the storage periods, except the group with 5.0% GCHE. The redness of all the samples was lower than that of control, while yellowness of all the samples was higher than that of control. The nitrite scavenging abilities of the sausages containing 1.0 and 5.0% GCHE were higher than that of the control. It is suggested that the addition of 1.0% hot water extracts extracted from these plants may be a potential substitute for the use of nitrite to extend shelf-life of sausages.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.455-463
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• 2012

In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

• Spatial Information Research
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• v.22 no.3
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• pp.71-77
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• 2014

There are numbers of unpredictable risk factors in the disaster scenes such as fire, explosion and fail to early life-saving or holding the flames which can lead to massive damage. In particular, fire-fighters who arrive on the scene within 5 minutes after dispatching, have a limitation to get aware to the situation of scene fully, because of immediate deploy to disaster scene with limited information. This situation may lead to disturbance that fire-fighters perform effective fire-fighting activities, to put fire-fighter's life at risk by misjudge the situation. Previous domestic and International studies focused vulnerability for spatial area or features which can damage to life and property in the event of anticipated. In this study, we have been developed fire-fighting vulnerable zone model that can analyze comprehensively hindrance factors for fire-fighting activities targeting whole life cycle of fire-fighting activities from dispatch to fire suppression or life-saving. In addition, we have been given shape to finality and applicability for our model by defining the new concept of fire-fighting vulnerable zone which can be distinguished from the concept of fire vulnerable area in previous studies. The results of this study can be used to analysis fire-fighting vulnerable zone type analysis, establish fire-fighting policies and improve the performance of decision-making process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1446-1451
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• 2013

The quality characteristics of pork patty prepared with chitosan containing preservatives during storage at $4^{\circ}C$ were investigated to improve its functional property and shelf life using food preservatives of natural origin (PI; 0.1% chitosan, 2.5% citric acid, 100 ppm grapefruit seed extract, 0.2% adipic acid, 0.1% Cinnamomum extract, D.W. 97.09% and PII; 0.1% chitosan, 2.5% citric acid, 100 ppm grapefruit seed extract, 0.2% adipic acid, 0.1% Lysimachia christinae Hance extract, D.W. 97.09%). The sensory qualities (taste, appearance, texture and overall acceptability) of patties preserved with PI (1, 3 and 5%) and PII (1, 3 and 5%) were also investigated. The taste and overall acceptability of patties prepared with 1% PI and 1% PII were higher than those of the control. The DPPH radical scavenging activities of the control, 1% PI and 1% PII treated patties were 13.54%, 21.78% and 14.07%, respectively. The total aerobes and coliform count of patties preserved with 1% PI were $10^4$ CFU/g and $10^2$ CFU/g, respectively, after 10 days storage at $4^{\circ}C$. Cooking loss from 1% PI and 1% PII treated patties was lower than that of from the control. Water holding capacity was the highest for 1% PI (65.84%), followed by 1% PII and then the control. The shelf life of patties prepared with 1% PI and 1% PII was extended by about 5 days relative to the control at $4^{\circ}C$.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.180-191
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• 2013

The purpose of this research was to find an optimal quarrying for marble by analyzing the applicability and the work efficiency of a chain saw machine newly introduced in the underground Baekwoon mine. From the test results of the physical properties of Baekwoon marble, which affects the efficiency of rock cutting, it was found to have similar physical characteristics as the ones which are now being produced in the other areas in Korea. And especially it shows isotropic property, which can be thought to be advantageous as a dimensional stone. To check the long-term quality of the marble as a stone material, several tests such as corrosion resistance test and abrasion test were carried out. It was found to be vulnerable to acid rain with decrease of weight and seismic wave velocity after applying artificial rain at pH 5.6 for 50 times. The percentage of wear from abrasion test was 22.67%. The working time and cutting speed of the chain saw machine were recorded and analyzed during the test-run at the quarry. The overall work cycle was assorted into 9 unit operations and the operating time per each unit was drawn. The operating times for the two cutting patterns, which could be possibly applicable to the work site, were compared. The results indicated that the pattern B, that the cutting sequence was set to minimize the movement of the machine, showed 6% less working hours than the pattern A, which first cuts the outer boundary. With cutting pattern analysis, the ore body in the Baekwoon mine was 3 dimensionally modeled and a quarrying plan considering the existing conditions of the marble was suggested.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.819-825
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• 2018

Porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were prepared by applying both template method and Kirkendall diffusion effect to electrospinning process. During heat-treatment processes, the solid Fe nano-metals formed by initial heat-treatment in the carbon matrix were converted into the hollow structured ${\alpha}-Fe_2O_3$ nanospheres. In particular, PS nanobeads added in the spinning solution were decomposed and formed numerous channels in the composite, which served as a good pathway for Kirkendall diffusion gas. The resulting porous nanofibers comprising hollow ${\alpha}-Fe_2O_3$ nanospheres were applied as an anode material for lithium-ion batteries. The discharge capacities of the nanofibers for the 30th cycle at a high current density of $1.0A\;g^{-1}$ was $776mA\;h\;g^{-1}$. The good lithium ion storage property was attributed to the synergetic effects of the hollow ${\alpha}-Fe_2O_3$ nanospheres and the interstitial nanovoids between the nanospheres. The synthetic method proposed in this study could be applied to the preparation of porous nanofibers comprising hollow nanospheres with various composition for various applications, including energy storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.449-455
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• 2020

Inventory management is one of the important business functions for manufacturing companies to determine market responsiveness. Customers' needs are diversifying, and the life cycle of products is decreasing, thus increasing the importance of inventory management. However, for small-scale manufacturing companies, investing in an IT system for inventory management is practically difficult. In this study, we introduce an inventory and warehouse management model that can be applied simply and quickly in small-scale manufacturing companies. Firstly, we introduce the concept of the properties of inventory and provide an analytical methodology based on the age and quantity of the inventory. Secondly, in accordance with the properties of the inventory, we introduce location management rules for warehouse operation. To apply the proposed model, we studied a wallpaper manufacturing company and verified the applicability of the proposed methods in the field. The proposed model can be applied immediately as part of on-site improvement activities by small-scale manufacturing companies, and inventory management activities are expected to reduce bad long-term inventory and further secure storage capacity for warehouses.