• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.997-999
• /
• 2013

In this paper, the frequency monitoring system for the small AC generator having two or more generator is designed and implemented to synchronize a voltage, phase and frequency for stable power supply. CT sensor is used to measure the amount of current flowing in the power line, and PT sensor is used to measure the amount of voltage across the power line. The experimental results show that the power frequency can be measured using the power frequency monitoring system developed in this paper. The frequency monitoring system proposed in this paper will be able to control the power generation system using two or more small generator efficiently.

• Journal of Plant Biology
• /
• v.30 no.4
• /
• pp.299-309
• /
• 1987

The seasonal pattern and the annual magnitude of the internal (or biochemical) and plant-soil cycles of phophorus in adjacent three different herb plant populations-Helianthus tuberosus L., Artemisia princeps Pampan and Phalaris anundinacea L.-in an old field of the basin in the Mt. Geumoh were investigated. A lot of the phosphorus demand for the three populations was supplied by the withdrawal from below-ground organ in early growing period, by the absorption from soil in mid-growing period and by the withdrawal from stem in later growing period. But in the A. princeps and P. arundianacea populations, a great deal of phosphorus seemed to be absorbed prior to the first withdrawal. The annual amount of the phosphorus flowing throughthe internal cycle was about 59% of the total hosphorus flow on theorgan level in the H. tuberosus population, 41% in the A. princeps population and 32% in the P. arundinacea population, indicating that the tuber plant had the most developed internal cycle system. The annual amount of phosphorus which took part in the plant-soil cycle in the stand of the three populations was in the range of 4.49-5.65 gPm-2, corresponding to only 3-8% of the extractable phosphorus contained in the soil of 0-20 cm depth. The fact that the H. tuberosus population is higher in the extent fo internal cycle but smaller in the magnitude of plant-soil cycle and lower in the turnover rate of phsophorus than the other two populations suggests that the growth of H. tuberosus population may be less dependent on soil phosphorus availability than those of the other two populations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.6
• /
• pp.526-531
• /
• 2009

In this paper, the safety for passengers of composite car-body against lightning strikes was analyzed by the application of an impulse generator which can produce impulse current up to 50 kA with 8/$20{\mu}s$ waveform. Potential difference on inside surface of the car-body was measured as a safety parameter for the passengers against lightning strikes. The potential difference between 20 em distant was 175 V at 37.67 kA, and it corresponds to 875 V between 1 m distant. The amount of charge flowing a passenger at 100 kA impulse current can be estimated to $0.31\;mA{\cdot}s$. This is much less than the limit amount of charge for human body, $30\;mA{\cdot}s$ which is presented by Koeppen and Osypka.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.1
• /
• pp.33-47
• /
• 2013

When a bomb explodes near a tunnel, generated muck should be quickly moved outside for rehabilitation of the tunnel. In this study, the amount of muck generated by an explosion was estimated and a methodology was presented for the prediction of the muck hauling time. To this end, 3D-meshes were made by using SoildWorks and blasting analyses were performed by using AUTODYN. A method was suggested to calculate theoretically the amount of muck which inflows into a tunnel based on the relationship between the tunnel and the fragmentation zone obtained from the analysis results. Also, muck hauling times were predicted based on the selection of construction equipment and the results were compared and analyzed. As a result, it was convinced that the amount of muck flowing into the tunnel could be effectively calculated by classifying the relationship between a tunnel and the fragmentation zone into 4 cases and using the mensuration by parts. Also it was confirmed that the closer blasting location is to the portal and the excavation surface of a tunnel, and the more blasting location deviates from the center line of the tunnel, the lesser amount of muck occurs and thus the muck hauling time decreases as well.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.3
• /
• pp.126-135
• /
• 2013

Recently, mass concrete with high flowability are widely used to improve the quality and constructability in the longer span construction of prestressed concrete bridges, but it may induce nonstructural cracks due to the hydration heat and autogenous shrinkage etc. The stresses in concrete were evaluated by various experiments and numerical analysis. The tensile stress in mass concrete was increased in connection with the accumulation of hydration heat. Moreover, large amount of autogenous shrinkage from powder type admixture could add the tensile stress to mass concrete near anchorage zone. The tensile stresses in anchorage zone by heat and autogenous shrinkage exceeded the tensile strength of early stage of concrete, and small amounts of stress increasement were shown in other parts of PSC girder.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.5
• /
• pp.1275-1284
• /
• 2004

This paper discuss the acupoints and flowing of channel. The Acupoints issued from the Foot Taiyin channel's energy are seventy three. The acupoints issued from the Foot Shaoyang channel's energy are sixty two. The acupoints issued from the Foot Yangming channel's energy are sixty eight. The acupoints issued from the Hand Taiyang channel's energy are thirty six. The acupoints issued from the Hand Yangming channel's energy are twenty two. The acupoints issued from the Hand Shaoyang channel's energy are thirty two. The acupoints issued from the Du channel's energy are twenty eight. The acupoints issued from the Ren channel's energy are twenty eight. The acupoints issued from the Chong channel's energy are twenty two. The acupoints issued from the Foot Shaoyin channel are the Lianquan points of kidney channel on each side under the tongue. The total points above amount of three hundred and sixty five. Urinary Bladder Channel of Foot-Taiyang: The number of acupoints is 67. Gall Bladder Channel of Foot-Shaoyang: The number of acupoints is 44. Stomach Channel of Foot-Yangming: The number of acupoints is 45.

• Journal of the Korean GEO-environmental Society
• /
• v.3 no.1
• /
• pp.67-77
• /
• 2002

Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

• Progress in Superconductivity
• /
• v.8 no.2
• /
• pp.186-192
• /
• 2007

High $J_c\;YBa_2Cu_3O_{7-x}$ superconducting films have been fabricated $LaAlO_3(100)$ substrate by MOD method using dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. Heating rate was varied in order to optimize the calcination heat treatment condition in DCA-MOD method. Coated films were calcined at lower temperature up to $500^{\circ}C$ in flowing humid oxygen atmosphere. The heating rate was calcined from $13.3^{\circ}C/min\;to\;0.28^{\circ}C/min$. Conversion heat treatment was performed $800^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. Surface and cross sectional SEM microstructures showed that particle sizes were increased with heating rate at a calcination step. The amount of pores was increased with heating rate in the calcined films. Dense microstructure and sharp texture were developed in an YBCO films after conversion heat treatment. A high critical current density (Jc) of $1.26MA/cm^2$ (@77 K and self-field) was obtained for the YBCO film which was prepared with a heating rate of $0.28^{\circ}C/min$.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.6
• /
• pp.198-204
• /
• 2010

The cover of truck agitator give in a part to prevent the lower flowing of fresh concrete when the concrete are transported from the ready mixed concrete plant to the construction field. As a result of the question data, it show up a dirty image to the general civil society. Due to the above image, it is predicted to affect the image of the construction company, so we did the site experiment of the flowing, the amounts of air, the temperature change of concrete with the concrete left in the site, to find out the usefulness. Also, for the comparing with this, we got the result by doing the inner experiment with the same condition. As the result of the experiment, the cover of truck agitator affect little to the reduction of slump. The change of the air amount, regardless of the existence of cover, was not effected much in proper level until 60minutes. In addition, The compression strength was proper to the goal design strength until 90minutes regardless of the cover of truck agitator exist or not exist.

• Journal of Environmental Impact Assessment
• /
• v.31 no.5
• /
• pp.334-342
• /
• 2022

The stringent air environment conservation act forced to build an indoor dome for coal storage. However, it causes some problems due to accumulation of fly ash and harmful substances inside. To solve this problem, this study analyzed the pattern of internal airflow and the amount of ventilation for an indoor coal yard. Overall, the airflow inside the indoor coal yard tended to move to the southwest facing the mountain. In addition, sea-breeze was blowing from the northern louver window facing the sea, where airflow was flowing in. The total flow rate flowing into the indoor coal yard was 918,691 m³/h, and the number of natural ventilation per hour was 0.6 times. Therefore, it is proposed to install a forced ventilation device at the location where internal air flow is concentrated.