• Journal of Korean Physical Therapy Science
• /
• v.12 no.4
• /
• pp.79-87
• /
• 2005

The purposes of this study were to test the effects of the low power laser and exercise on the recovery in the cerebellar injured rats by 3-Acetylpyridine. Cerebellar injury was induced by 3-Acetylpyridine chemoablation of the inferior olive. Thirty Sprague-Dawley rats were assigned to the normal control and 3AP control and 3 experimental groups. Each experimental group was treated from 5 days after being injured for the 5 min(laser group), 10 min(exercise group) and 15min(exercise with laser) everyday during the 2 weeks. The Hindlimb splay test, Vestibular drop test, Hindlimb stride width test, Maximal Height Vertical Jump test were examined at pre-treatment on 1st day and 5th, 10th, 14th days after treatment on the cerebellar injured rats by 3AP. The results of this experiment were as follows; There were significantly increased exercise on the 3 experimental groups comparied with the 3AP control group, in the Hindlimb splay test, Vestibular drop test, Hindlimb stride width test, and Maximal Height Jump test(P<.05).

• Journal of the Korean Society for Railway
• /
• v.13 no.5
• /
• pp.500-503
• /
• 2010

Until now, the track circuit with railroad which is a part of an electrical circuit wad used only for the detection of the train location, but as train speed is up to be higher, in order to overcome the limits of ground signal system the railway signal system has changed from the ground signal system to a cab signal system. The power source of the track circuit has also changed from a direct current or a high voltage impulse to an alternating current with high frequency which is a part of the audio frequency. To improve the maintenanability and according to the environment condition, the railway roadbed is rapidly changed to the ferroconcrete roadbed. In case of a track circuit to use an alternating current with high frequency as power source at a ferroconcrete roadbed, the characteristic of the track circuit is brought on a change from a loss of the magnetic combination instead of a leakage current from electric insulation which was caused by the reinforcing iron pod with lattice shape for durability. This paper is shown the influence and the loss of the signal current at AF track circuit on a ferroconcrete in the simulation sheets and presented a proposal for the preventive method from reduction of signal current.

• Journal of the Korea Convergence Society
• /
• v.2 no.2
• /
• pp.35-45
• /
• 2011

Recently, with the increasement of the interest about global warming, pollutions, and so on, a number of distributed generations(DGs) such as photovoltaic(PV) and wind power(WP), are interconnected with distribution systems. However, installing of DGs makes power flow changes such as directions, one-direction to bi-direction, and increasing/decreasing of fault current. Therefore, it may cause the critical problems. This paper proposes an evaluation algorithm for bi-directional protection coordination and presents an evaluation system for protection coordination based on this algorithm. Additionally, the result shows that the existing method may cause critical problems, and also the effectiveness of proposed method is verified.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.2
• /
• pp.179-187
• /
• 2010

The purpose of this study is to suggest the advancement of the competitive power of Korean electronics and automobile industries from a product-architectural point of view. There are two types for the characteristics of parts. They are the modular type and the integral type. The former is very independent between one subsystem and another, whereas the other is very dependent. The distinction of product architecture makes them different for the ability to organize developing products suited for the product manufacturing. The organizing ability is generally divided into the abilities of 'modulation integration' and 'selection assembly'. For the integral products such as cars, the integration ability is important between an enterprise and another, as well as between a part and another. However, the modular products such as a PC need the ability to select and effectively organize optimal parts or enterprises. The strategy raising product competitiveness is pursued by synthesizing 'design manufactu-turing strategy' for the product architecture and 'customer value strategy' for the customer values.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.114-123
• /
• 2018

Recently, as one of the countermeasures to reduce carbon dioxide($CO_2$) for global warming problems, operation methods in micro-grid systems replacing diesel generator with renewable energy sources including wind power(WP) and photovoltaic(PV) system have been studied and presented in energetic manners. However, it is reported that some operation problems in micro-grid systems without diesel generator for carbon-free island are being occurred when large scaled WP systems are at start-up. To overcome these problems, this paper proposes an operation strategy in micro-grid systems by adapting control devices such as CVCF(constant voltage constant frequency) ESS(energy storage system) for constant frequency and voltage regulation, load control ESS for balancing demand and supply and SVC(static-var compensator) for reactive power compensation. From the simulation results based on the various operation scenarios, it is confirmed that the proposed operation strategy in micro-grid systems without diesel generators is a useful tool to perform a stable operation in micro-grid systems without diesel generator and also make a contribution to reduce carbon dioxide in micro-grid systems.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1988-1989
• /
• 2007

Polyethylene is widely used as the insulator for power cable. To investigate the conduction mechanism for power cable insulation under ac high field, it is very important to acquire the dissipation current under actual running field. Recently, we have developed the unique system, which make possible to observe the nonlinear dissipation current waveform. In this system, to observe the nonlinear properties with high accuracy, capacitive current component is canceled by using inverse capacitive current signal instead of using the bridge circuit for canceling it. We have already reported that the dissipation currents of $40\;{\mu}m$ thick LDPE film at 10 kV/mm and over 140 Hz, it starts to show nonlinearity and odd number's harmonics were getting large. To investigate the conduction mechanis ms in this region, especially space charge effect, various kinds of estimation, such as time variations of instantaneous resistivity for one cycle, FFT spectra of dissipation current waveforms and so on, has been examined. As the results of these estimations, it was found that the dissipation current will depend on not only the instantaneous value of electric field but also the time differential of applied electric field due to taking a balance between applied field and internal field. Furthermore, two large peaks of dissipation current for each half cycle were observed under certain condition. In this paper, to clarify the reason why it shows two peaks for each half cycle, the film thickness dependences of dissipation current waveforms were observed by using the three different thickness LDPE films.

• Solar Energy
• /
• v.14 no.2
• /
• pp.39-50
• /
• 1994

Experiments have been conducted to measure the heat transfer coefficient and pressure drop in fluidized bed double pope heat exchangers with smooth tube and longitudinal finned tube. The effect of particle size(alumina beads; do=0.41, 0.54, 0.65, 0.77 mm) and static bed height on the heat transfer coefficient has been evaluated in terms of pumping power. The heat transfer coefficient for the smooth tube and finned tube heat exchangers has been compared with single phase double pipe heat exchanger. Results show that the heat transfer coefficients for the finned tube in $2.96{\sim}3.45$ times higher than the smooth tube. The heat transfer coefficients for the fluidized bed heat exchanger is higher than the single phase heat exchanger for the most of pumping power range tested. The maximum increase in the heat transfer coefficient for fluidized bed is 91.3% for the smooth tube and 127.1% for the finned tube.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.55 no.6
• /
• pp.858-866
• /
• 2022

The present study investigated the chemical composition, and antioxidant and physiological activities of the Korean marine algae, Codium fragile. The solvent extracts from C. fragile were prepared using 70% ethanol, 80% methanol, and distilled water. Based on the general chemical composition, carbohydrate, crude protein, crude lipid, crude ash, and moisture were 74.22%, 16.73%, 0.66%, 4.39%, and 4.00%, respectively. Calcium, magnesium, sodium and potassium were the main minerals. The extraction yield range of the solvent extracts was 3.51-9.76%. The ranges of total polyphenol and flavonoid contents were approximately 10.97-13.76 mg/g and 8.00-8.69 mg/g, respectively. The ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)] radical scavenging activity, reducing power and FRAP (ferric reducing antioxidant power) activities were the highest in the ethanol extract, while methanol extract exhibited the strongest nitrite oxide scavenging activity. On the other hand, tyrosinase, elastase, and xanthine oxidase inhibitory activities of the ethanol and methanol extracts were higher than those of the water extract. Furthermore, the ethanol extract exhibited the highest β-secretase inhibitory activity. The results indicate that C. fragile can be used as an antioxidant and a functional ingredient in food and pharmaceutical products.

• Journal of Environmental Science International
• /
• v.32 no.6
• /
• pp.429-440
• /
• 2023

Quantitative habitat model is established with species occurrence and spatial abundance data, which were usually acquired by professional field ecologists and citizen scientists. The importance of citizen science data is increasing, but the quality of these data needs to be evaluated. This study aims to identify and compare both expert-based data and citizen science data based on the performance power of quantitative models derived from both data sets. A Maximum Entropy (MaxENT) model was developed using eight environmental variables, including climate, topography, landcover and distance to forest edge. The AUC values derived from the MaxENT model were 0.842 and 0.809, respectively, indicating a high level of explanatory power. All environmental variables has similar values for both data sets, except for the distance to forest edge and rice paddy, which was relatively higher for expert-based survey data than that of the citizen science data as the distances increased. This result suggests that habitat model derived from expert-based survey data shows more ecological niche including wider ranges from forest edges and isolated habitat patches of rice paddy. This is presumably because citizen scientists focuses on direct observation methods, whereas professional field surveys investigate a wider variety of methods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.704-712
• /
• 2016

Recently, the installation of photovoltaic (PV) systems has been increasing due to the worldwide interest in eco-friendly and infinitely abundant solar energy. However, the output power of PV systems is highly influenced by the surrounding environment. For instance, a string of PV systems composed of modules in series may become inoperable under cloudy conditions or when in the shade of a building. In other words, under these conditions, the existing control method of PV systems does not allow the string to be operated in the normal way, because its output voltage is lower than the operating range of the grid connected inverter. In order to overcome this problem, we propose a new control method using a DC-DC voltage regulator which can compensate for the voltage of each string in the PV system. Also, based on the PSIM S/W, we model the DC-DC voltage regulator with constant voltage control & MPPT (Maximum Power Point Tracking) control functions and 3-Phase grid connected inverter with PLL (Phase-Locked Loop) control function. From the simulation results, it is confirmed that the present control method can improve the operating efficiency of PV systems by compensating for the fluctuation of the voltage of the strings caused by the surrounding conditions.