• Progress in Medical Physics
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• v.21 no.2
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• pp.209-217
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• 2010

Retinal prostheses are being developed to restore vision for the blind with retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Since retinal prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. Therefore, in this paper, we focused on retinal ganglion cell (RGC) responses to different voltage stimulation parameters and compared threshold charge densities in normal and rd1 mice. For this purpose, we used in vitro preparation for the retina of normal and rd1 mice on micro-electrode arrays. When the neural network of rd1 mouse retinas is stimulated with voltage-controlled pulses, RGCs in degenerated retina also respond to voltage amplitude or voltage duration modulation as well in wild-type RGCs. But the temporal pattern of RGCs response is very different; in wild-type RGCs, single peak within 100 ms appears while in RGCs in degenerated retina multiple peaks (~4 peaks) with ~10 Hz rhythm within 400 ms appear. The thresholds for electrical activation of RGCs are overall more elevated in rd1 mouse retinas compared to wild-type mouse retinas: The thresholds for activation of RGCs in rd1 mouse retinas were on average two times higher ($70.50{\sim}99.87\;{\mu}C/cm^2$ vs. $37.23{\sim}61.65\;{\mu}C/cm^2$) in the experiment of voltage amplitude modulation and five times higher ($120.5{\sim}170.6\;{\mu}C/cm^2$ vs. $22.69{\sim}37.57\;{\mu}C/cm^2$) in the experiment of voltage duration modulation than those in wild-type mouse retinas. This is compatible with the findings from human studies that the currents required for evoking visual percepts in RP patients is much higher than those needed in healthy individuals. These results will be used as a guideline for optimal stimulation parameters for upcoming Korean-type retinal prosthesis.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.65-72
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• 2006

Recent technical advances in the biorecognition engineering and the microparticle fabrication may enable us to develop the single step purification using magnetic particle, because of its simplicity, efficacy, ease of automation, and process economics. In this study, we used commercial magnetic particles from Seradyn, Inc. (Indianapolis, USA). It was ca. 2.8 micron in diameter, consisted of polystyrene core and magnetite coating, and its surface had carboxyl groups. The model, capture protein was IgG and anti-IgG was used as the ligand molecule. We studied the different surfaces ('nude', ester-activated, and anti-IgG coated) for their biorecognition of IgG. At a high pH condition, we could reduce non-specific binding. Also anti-IgG immobilized magnetic particle could capture IgG more selectively. We attempted 'oriented immobilization' of anti-IgG, in which the polysaccharides moiety near the C-terminus was selectively oxidized and linked to the hydrazine-coated MP, to improve the efficacy of biorecognitive binding. Using this method, the IgG capturing ability was improved by ca. 2 fold. From the binary mixture of the IgG-insulin, IgG could be more selectively captured. In summary, the oriented immobilization of oxidized anti-IgG proved to be as effective as the streptavidin-biotin system and yet simpler and cost-effective. This immobilization method can find its applications in protein biochips and biotargeting.

• Journal of Chest Surgery
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• v.35 no.3
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• pp.199-208
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• 2002

Background: The washing of packed red blood cells could remove pro-inflammatory mediators, cell debris, and micro-particles contained in packed red blood cells, and the preci-rculation-ultrafiltration (recirculation and ultrafiltration of circuit itself before cardiopulmonary bypass) could attenuate the initial inflammatory reaction and remove the initial proinflam-matory mediators. This study was performed to evaluate whether the washing of packed red blood cells and precirculation-ultrafiltration can reduce the production of cytokines that have an important role in myocardial reperfusion injury. This study investigated the effects of washing the packed red blood cells and precirculation-ultrafiltration on the production of cytokines during and after cardiopulmonary bypass and open heart surgery. Material and Method: Forty eight infants with VSD undergoing open heart surgery under cardiopulmonary bypass were randomized into control group (group C, n=12), washing group (group W, n= 12), precirculation-ultrafiltration group (group F, n: 12), and combined group(washing and precirculation-ultrafiltration, group WF, n=12). Blood samples were obtained before, during, and after the bypass to assess plasma level of tumor necrosis factor-$\alpha$(TNF-$\alpha$), interleukin-6(IL-6), and interleukin-8 (IL-8). Results: Expressions of TNF-$\alpha$ were significantly reduced in combined group (group WF) compared with group C, group W, and group F (p<0.05). Expression of IL-6 were significantly reduced in group W, group F, and group WF compared with group C (p<0.05), but similar among group W, group F, and group WF (p=0.053). Expression of IL-8 were reduced in group W and group WF compared with group C (p<0.05), but similar among group W, group F, and group WF (p=0.067). Conclusion: In conclusion, the washing of packed red blood cells and precirculation-ultrafiltration blunted the increase of TNF-$\alpha$ , IL-6, and IL-8 during and after open heart surgery with cardiopulmonary bypass. However, the clinical benefits of these treatments remains unproven.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.435-440
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• 2008

Bovine mastitis is an important disease causing serious economic loss in dairy production and food poison in public health. The major causative agents of bovine mastitis include Escherichia coli (E. coli), Streptococcus agalactiae (S. agalactiae), Staphylococcus aureus (S. aureus). These bacteria were found in milk and environmental condition such as feces, water, soil and so on. Recently, many cases of mastitis are derived from environmental contamination of micro-organisms, which important factors for the spread of this disease in farm. Ultraviolet irradiation (UV) has been used as disinfection for waste and water in clinical and industrial facilities. Moreover the UV irradiation has been used as useful bactericidal agents to remove bacterial biofilms in environmental condition. In this study, we determined the bacterial replication in different percentage of water content (PWC) in sterilized saw dust and feces complexes from farm, and results showed that slightly decreased growth pattern of E. coli and S. agalactiae but increased growth pattern of S. aureus in various PWC (200, 400 and 600%) until 144 h incubation. In the bacteriocidal effect of UV irradiation to bacteria in saw dust and feces complex, the results showed that bacteriocidal effect was depended on the UV irradiation time, irradiation distance and PWC. Especially the antibacterial activity of UV irratiation is stronger in low PWC (50%), long time irradiation (50 sec), and short distance (5 cm) than other condition of this study. Furthermore UV irradiation with stirring showed increased the bactericidal effect compared without stirring. These results suggested that bovine mastitis causing agents may survive long time in environmental condition especially saw dust and feces complexes in farm and can cause a various disease including mastitis. Moreover, these data can be used as basis for application and development of UV disinfection to control of bovine mastitis from environmental contaminated bacteria in dairy farm.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.129-155
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• 2008

The rate of antibiotics prescription for an acute airway infection significantly varies depending upon the diagnosis type, specialty, and the location of the hospital along with many other related factors. The objective of this study is to empirically investigate the possible relationship between the antibiotics prescription rates for an acute airway infection and the degree of competition in the hospital market regions of mainly the providers of primary medical care services such as clinics, internal medicines, pediatrics and otorhinolaryngology department. Using the data from Health Insurance Review and Assessment Service (HIRA) regarding the hospitals' antibiotics prescription rates for the acute airway infection and controlling for selected variables of demand and supply sectors, this study tries to figure out that the degree of competition in the hospital market, regardless of what type of competition indexes we employed, has a statistically significant effect on the variations of antibiotics prescription rate of the clinics in local areas. This result implies that as an economic consideration itself, the change in the degree of competition in the hospital market can play a crucial role influencing the treatment behaviors of the medical doctors. More specifically, this study reveals that as the degree of competition increases the antibiotics prescription rate goes up. This result means that if the market becomes more competitive in a specific region so that it might cause a reduction in doctor's income, doctors with rational decision-making process, recognize that the benefit created from inducing patients' seemingly unnecessary demand for medical care (income effect) would be higher than the costs associated with sustaining their targeted income (substitution effect). It is because that the doctors are more likely to prescribe antibiotics which create relatively higher margins than other medical care services in order to sustain their targeted income when the hospital market competition becomes tighter. Even though this study empirically confirms that antibiotics prescription can be affected by the economic incentives, it still raises following issues as limitations of the study: first issue is about the representativeness of the hospital regions segregated for this study, which might be weak in explaining whether these regions are mutually exclusive in reality. Patients actually consider the quality of services, transportation cost, time costs, and any other related factors choosing the doctors or hospitals, and in that sense, this study rules out 'border-crossing' in using the medical care services. Second issue arises in capturing the data of antibiotics prescription rate. Since we use the average rate for each medical institution, we cannot figure out the average rate for each patient so that we are not able to control for the variation of patients' medical conditions. It is because of the unavailability of data regarding each patient's medical condition from HIRA. Thirdly, since this study mainly analyzes the medical institutions providing primary care such as clinics, internal medicines, pediatrics, and otorhinolaryngology department, it is skeptical of whether those institutions can represent the hospital market in respective regions and truly reflect the degree of competition. It needs to extend the study areas and disease types as well as any micro data for future studies.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.844-861
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• 2008

The papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during the year of 2007 have been reviewed. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro nano fluid, micropump and fuel cell. Traditional CFD was still popular and widely used in research and development. Studies about fans and pumps were performed in the field of fluid machinery. Characteristics of flow and fin shape optimization are studied in the field of piping system. (2) The research works on heat transfer have been reviewed in the field of heat transfer characteristics, heat exchangers, and desiccant cooling systems. The research on heat transfer characteristics includes thermal transport in pulse tubes, high temperature superconductors, ground heat exchangers, fuel cell stacks and ice slurry systems. For the heat 'exchangers, the research on pin-tube heat exchanger, plate heat exchanger, condensers and gas coolers has been cordially implemented. The research works on heat transfer augmenting tubes have been also reported. For the desiccant cooling systems, the studies on the design and operating conditions for desiccant rotors as well as performance index are noticeable. (3) In the field of refrigeration, many papers were presented on the air conditioning system using CO2 as a refrigerant. The issues on the two-stage compression, the oil selection, and the appropriate oil charge were treated. The subjects of alternative refrigerants were also studied steadily. Hydrocarbons, DME and their mixtures were considered and various heat transfer correlations were proposed. (4) Research papers have been reviewed in the field of building facilities by grouping into the researches on heat and cold sources, air conditioning and air cleaning, ventilation and fire research including tunnel ventilation, flow control of piping system, and sound research with drain system. Main focuses have been addressed to the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies were mostly focused on analyzing the indoor environment in various spaces like cars, old tombs, machine rooms, and etc. in an architectural environmental field. Moreover, subjects of various fields such as the evaluation of noise, thermal environment, indoor air quality and development of energy analysis program were researched by various methods of survey, simulation, and field experiment.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.5
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• pp.50-60
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• 2010

For the last half a century, the personal computer and software industries have been prosperous due to the incessant evolution of computer systems. In the 21st century, the embedded system market has greatly increased as the market shifted to the mobile gadget field. While a lot of multimedia gadgets such as mobile phone, navigation system, PMP, etc. are pouring into the market, most industrial control systems still rely on 8-bit micro-controllers and simple application software techniques. Unfortunately, the technological barrier which requires additional investment and higher quality manpower to overcome, and the business risks which come from the uncertainty of the market growth and the competitiveness of the resulting products have prevented the companies in the industry from taking advantage of such fancy technologies. However, high performance, low-power and low-cost hardware and software platforms will enable their high-technology products to be developed and recognized by potential clients in the future. This paper presents such a platform for industrial embedded systems. The platform was designed based on Telechips TCC8300 multimedia processor which embedded a variety of parallel hardware for the implementation of multimedia functions. And open-source Embedded Linux, TinyX and GTK+ are used for implementation of GUI to minimize technology costs. In order to estimate the expected performance and power consumption, the performance improvement and the power consumption due to each of enabled hardware sub-systems including YUV2RGB frame converter are measured. An analytic model was devised to check the feasibility of a new application and trade off its performance and power consumption. The validity of the model has been confirmed by implementing a real target system. The cost can be further mitigated by using the hardware parts which are being used for mass production products mostly in the cell-phone market.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.94-131
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• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• Journal of Life Science
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• v.19 no.7
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• pp.956-962
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• 2009

The aim of this study was to assess the effects of dentifrice-contatning grapefruit seed extract (GSE) and processed sulfur solution (PSS) on antimicrobial effects against oral pathogens. We first evaluated the antimicrobial effects of GSE and PSS against oral microbes: Streptococcus mutans (Sm), Prevotella intermedia (Pi), Porphyromonas gingivalis (Pg) and Candida albicans (Ca). When antimicrobial activity against Sm, Pi, Pg and Ca was tested, at 40 $\mu$l/disk, the inhibition zones of GSE were 11.0, 9.5, 8.0 and 9.0 mm, respectively. With the same method, the inhibition zones of PSS were 2.0, 3.5, 0.0 and 1.5 mm, respectively. In the micro broth dilution method, the MIC values of GSE against Sm, Pi, Pg and Ca were 0.24, 0.06, 0.10 and 15.63 $\mu$l/rnl, respectively. The MIC values of PSS were 0.12, 3.91,>125 and 7.81 $\mu$l/ml, respectively. When pH, refractive index, viscosity and color value of dentifrice-containing GSE and PSS were measured, there were no significant changes in these physical properties compared to the control samples. Antimicrobial activities of dentifrice products containing 0.5% GSE and 0.5% PSS against oral pathogens were 7.3, 4.3, 2.2 and 1.5 mm, respectively. According to these results, we conclude that there may be a role for GSE and PSS in the development of new oral supplies.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.35-48
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• 2014

In order to estimate the effect of additional nutrients on phytoplankton growth and horizontal phytoplankton community distribution during the autumn season in 2010 and 2011, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Also, nutrient additional experiments were conducted to assess additional nutrient effects on phytoplankton assemblage using the surface water. In both years, the total nutrients were high at the enclosed inner bay and the mouth of Seomjin River, whereas it was low at the St.15~20 where in influenced by the surface warm water current from offshore of the bay. On the other hand, nano- and pico-sized Chl. a were gradually increased towards the outer bay and their trends were significant in 2011 than in 2010. The cryptophyta species occupied more than 85% of total phytoplankton assembleges in 2010, whereas their abundance in 2011 remainds to be 1/10 levels of 2010. Following the cryptophata species, the diatom Chaetoceros spp. and Skeletonema-like spp. were found to be dominant species. Further the biosaasy experimental results shows that the phytoplankton biomass in the +N and +NP treatments was higher compared to control and +P treatments and its trend was significant at St.8 and St.20 where nutrient concentration were low. Based on the bioassay and field survey, providing the high nutrients may have stimulated to phytoplankton growth such as S. costatum-like spp.. In particular, opportunistic micro-algae such as Cryptomonas spp. were able to achieve the high biomass under the relatively mid nutrient condition from bottom after break down of seasonal stratification in the Gwangyang Bay.