• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2253-2260
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• 2009

The typical distribution systems have the power flow from distribution substations (sources) to customers (load) only as one direction. However, in the case where new energy power sources are connected to distribution systems, the output variations of new energy sources to distribution systems, which is so called reverse power flow, may cause the bi-directional power flow. So, the reverse power flow has severe impacts on typical power system, for example power quality problems, protection coordination problems, and so on. Therefore, this paper proposes the algorithm for Multi-functional protection devices in distribution systems in the case where new energy sources are interconnected. The proposed algorithm is verified to show the effectiveness by simulating and experimenting the prototype systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.927-934
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• 2019

Recently, mobile devices have evolved into small computers with various functions according to user requirements. Careful attention must be paid to the design of the power supply network for the stable operation of the application processor (AP), the wireless communication modem, the high performance camera, and the various interfaces of the mobile device to implement various functions of the mobile device. In this paper, we analyzed and verified the method of optimizing the design parameters such as the position, capacity, and number of decoupling capacitors to meet the target impedance required by the driver IC chip to ensure the stability of the power supply network of mobile devices that should be designed as wiring type due to mounting density limitation. The proposed wired power supply network design method can be applied to various applications including high-speed signal transmission line in addition to mobile applications.

• Journal of IKEEE
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• v.23 no.1
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• pp.289-294
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• 2019

At present, domestic small islands mainly supply electric power using diesel generators. However, diesel generators can cause instability of the power system due to slow response on power load fluctuation, and cause environmental problems due to the emission of carbon gas by using fossil fuels. In order to overcome this problem, this paper proposes a method to establish an optimal microgrid by introducing solar power, wind power, and energy storage device to Chujado Island, which is supplied with electric power through a diesel generator. The economical optimum capacity of each distributed power source is calculated by using HOMER (Hybrid Optimization Model for Multiple Energy Resources) program and the proposed microgrid is validated by using PSCAD/EMTDC (Power Systems Computer Aided Design/ Electromagnetic Transients including DC) program which can analyze system stability.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_2
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• pp.209-218
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• 2022

The purpose of this study is to analyze an economic assessment of PV-ESS systems based on the power generation performance data of solar power (PV) operating in domestic area, and to calculate the optimal capacity of the energy storage system. In this study, PVs in Gyeonggi-do, Jeollabuk-do, and Gyeongsangbuk-do were targeted, and PVs in this area were assumed to be installed on a general site, and the research was conducted by applying weights based on the facility's capacity. All the analysis was conducted using the actual amount of KPX transactions of PVs in 2019. In order to calculate the optimal capacity of PCS and BESS according to GHI, PV with a minimum/maximum/central value was selected by comparing the solar radiation before the horizontal plane between three years (2017-2019) of the location where PV was installed. As a result of the analysis, in Gyeonggi-do, if the REC weight decreases to 3.4 when there is no change in the cost of installing BESS and PCS, it is more economical to link BESS than PV alone operation of PV. In Jeollabuk-do, it was analyzed that if the REC weight was reduced to 3.6, it was more likely to link BESS than PV operated alone. In Gyeongsangbuk-do, it was analyzed that if the REC weight was reduced to 3.4, it was more likely to link BESS than PV operated alone.

• Journal of Korean Foot and Ankle Society
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• v.26 no.4
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• pp.177-182
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• 2022

Purpose: The efficacy and safety of low-dose pregabalin and alpha lipoic acid in diabetic neuropathy were evaluated and analyzed. Materials and Methods: This study designed a retrospective study that included patients with diabetic neuropathic pain. From 2009 to 2022, 100 patients who suffered from diabetic neuropathic pain were included in this study. The patients were divided into group I (pregabalin 150 mg/day with alpha lipoic acid 600 mg/day) and group II (pregabalin 300 mg/day with alpha lipoic acid 600 mg/day). The visual analogue scale (VAS), medication side effects, and neurometer results were compared. Results: The mean follow-up period of the above patients was 120.23 weeks in group I and 149.05 weeks in group II. The average VAS score in group I decreased by 3.23 points, and the average VAS score in group II decreased by 2.86 points. Approximately 24.3% of group I had side effects, such as dizziness, sleepiness, and gastrointestinal trouble, while 76.7% of patients in group II had side effects. Sixtyseven patients had a neurometer examination before and after the medication, and there is no statistical difference between the two groups. Conclusion: The combination of low-dose pregabalin (pregabalin 150 mg/day) and alpha lipoic acid in diabetic neuropathy had a similar clinical effect and less frequent medication side effects than regular dose pregabalin (pregabalin 300 mg/day) and alpha lipoic acid. Therefore, low-dose pregabalin (pregabalin 150 mg/day) and alpha lipoic acid should be considered in treating diabetic neuropathy.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.177-184
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• 2009

For the purpose of reducing the cost for greenhouse operation by acquiring the electric power necessary for it, this study installed a solar photovoltaic system on the roof of the building adjacent to green-houses and experimentally examined the quantity of power generation based on weather conditions. The results of the study are as per the below: The maximum, average and minimum temperature while the experiment was conducted was $0.4{\sim}34.1,\;-6.1{\sim}22.2$, and $-14.1{\sim}16.7^{\circ}C$ respectively, and the solar radiation was $28.8MJ{\cdot}m^{-2}$ (maximum), $14.9MJ{\cdot}m^{-2}$ (average), and $0.6MJ{\cdot}m^{-2}$ (minimum). The quantity of electric power didn't increase in proportion to the quantity of solar radiation and instead, it was almost consistent around 750W. Daily maximum, average and minimum consumption of electric power was 5.2kWh, 2.5kWh and 0kWh respectively. Based on the average electric power consumption of the system used for this experiment, it was sufficient in case the capacity and the working time of a hot blast heater are small, but it was short in case they are big. In case the capacity of the hot blast heater is big, the average electric power quantity will be sufficient for array area $21m^2$, about three times of the present area. In summer when the temperature of the array becomes high, the generation of electric power didn't increase in proportion to the quantity of solar radiation, but this experiment result shows a high correlation between two factors (coefficient of correlation 0.84).

• Tuberculosis and Respiratory Diseases
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• v.56 no.2
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• pp.178-186
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• 2004

Background : Photodynamic therapy (PDT) is a new therapeutic method aimed at the selective destruction of cancer cells. The outcome is death of cancer cells through apoptosis or necrosis. The aim of this study was to investigate the characterization of PDT induced cell death in A549 lung cancer cells. Materials and methods : A549 cells were used as the lung cancer cell. 5 aminolevulinic acid (ALA) was used as the photosensitizer and a 632nm diode laser (Biolitec, Germany) as the light source. Cells were incubated with various concentrations of ALA. The 632nm diode laser was then administered for various laser irradiation times. The treated cells were incubated with 24, 48 and 72 hours. The cell viabilities were measured using the crystal violet assay and light microscopy. To observe the cell death mechanism after PDT, cells were observed under fluorescence microscopy after double staining with Hoechst 33342 and propium iodide after PDT. Results : In the crystal violet assay at 24 hours after PDT with a $3.2J/cm^2$ laser irradiation power, the cell viabilities were $89.56{\pm}4.11$, $87.67{\pm}5.48$, and $69.37{\pm}8.84$ with ALA concentrations of 10, 100, and $1mg/m{\ell}$, respectively. In crystal violet assay at 24 hours after PDT with $1mg/m{\ell}$ of ALA, the cell viabilities were $74{\pm}19.85$, $55{\pm}6.1$, and $49.06{\pm}16.64%$ with 1.6, 3.2 and $6.4J/cm^2$ laser irradiation powers, respectively. However, increasing the interval time after PDT did not change the cell viabilities. In the apoptosis assay, photodynamic therapy was inducing the apoptotic cell death. Conclusions : This study shows the apoptotic anticancer effect of photodynamic therapy in A549 lung cancer cells. However, further evaluations with other cancer cells and photosensitizers are necessary.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.365-372
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• 2011

This study aimed to examine foundational data for container seedling production with the subject of Daphniphyllum macropodum community in Mt. Naejang National Park. To achieve the goal, it investigated the growth characteristics of young tree seedlings growing in places with different light intensity environment. Regarding the growth environment of Daphniphyllum macropodum community, it was typical heavy rain summer climate, and the soil was silt loam with the organic content as 11.42~15.61%, total nitrogen as 0.50~0.76%, cation exchangeable capacity (C.E.C) as 18.92~23.32 cmol/kg, and pH as 4.85~5.58. About light intensity environment changed by research plots, relative transmittance of solar radiation was 71~76% in plot A, 37~42% in plot B, 65~70% in plot C, and 28~33% in plot D. The seedlings tended to be intensively distributed either under the crown of their mother tree or in the slope site, and plot A and C where light intensity environment is relatively more favorable showed 1,550 tree/ha and 1,250 tree/ha. Total biomass production of Daphniphyllum macropodum seedlings was 5.37 g in plot A and 5.29 g in plot C, so they were higher than 4.42~4.51 g in plot B and D with relatively less favorable light intensity environment. The T/R ratio was 1~2, leaf area rate was $139.71{\sim}183.50cm^2{\cdot}g^{-1}$, leaf area ratio was $39.68{\sim}60.66cm^2{\cdot}g^{-1}$, and leaf dry weight ratio grew higher in the range of $0.28{\sim}0.33cm^2{\cdot}g^{-1}$ as the intensity of radiation became less. It is thought that in the generation and growth of Daphniphyllum macropodum seedlings, the intensity of light has more effects than the organic content in soil. And it is also thought that in the application of container seedlings production, light environment management over 65~70% to full sun light intensity will affect significantly the initial growth of Daphniphyllum macropodum.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.127-135
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• 2021

To respond to the threat of global warming, countries around the world are promoting the spread of renewable energy and reduction of carbon emissions. In accordance with the United Nation's Sustainable Development Goal to combat climate change and its impacts, global automakers are pushing for a full transition to electric vehicles within the next 10 years. Electric vehicles can be a useful means for reducing carbon emissions, but in order to reduce carbon generated in the stage of producing electricity for charging, a power generation system using eco-friendly renewable energy is required. In this study, we propose a smart electric mobility operating system integrated with off-grid solar power plants established in Tanzania, Africa. By applying smart monitoring and communication functions based on Arduino-based computing devices, information such as remaining battery capacity, battery status, location, speed, altitude, and road conditions of an electric vehicle or electric motorcycle is monitored. In addition, we present a scenario that communicates with the surrounding independent solar power plant infrastructure to predict the drivable distance and optimize the charging schedule and route to the destination. The feasibility of the proposed system was verified through test runs of electric motorcycles. In considering local environmental characteristics in Tanzania for the operation of the electric mobility system, factors such as eco-friendliness, economic feasibility, ease of operation, and compatibility should be weighed. The smart electric mobility operating system proposed in this study can be an important basis for implementing the SDGs' climate change response.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.700-705
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• 2009

Several studies have demonstrated that chlorophyll has many beneficial properties, including anti-inflammatory, anti-tumor, and antioxidant properties. Chlorophyll has been also shown to have an excellent chemopreventive potential against skin tumor. Its preventive mechanism against skin tumor, however, has not been examined in detail. Furthermore, the effects of chlorophyll on UVB-induced cellular responses have not been investigated. Solar UV radiation, in particular its UVB component, is the primary cause of many adverse biological effects, which is responsible for the photoaging and skin cancer. We investigated the preventive effects of chlorophyll a on UVB-mediated responses in human immortalized HaCaT kerationocytes and normal human fibroblast. We found that treatment of chlorophyll a markedly inhibited UVB-induced generation of reactive oxygen species and lipid peroxidation. Chlorophyll a also prevented UVB-induced MMP-1 expression and MMP-2 activation and increased Type I pN collagen synthesis. These results suggest that chlorophyll a is a potent candidate for the prevention and treatment of UVB-induced skin cancer and photoaging.