• Journal of Animal Environmental Science
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• v.12 no.2
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• pp.85-94
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• 2006

The effects of turning frequency of in-vessel composting on ammonia emissions during composting of separated solids from swine slurry/sawdust mixtures and performance of biofiltration using the chicken manure compost were investigated. Separated solids from swine manure amended with sawdust was composted in a 226 L laboratory-scale in-vessel reactors under various turning frequency and continuous airflow (0.6 L/min.kg.dm) for three weeks. Three laboratory-scale manure compost biofilters were built to treat effluent gas from the composting of separated solid from swine manure amened with sawdust process. These experiments were continued over a period of three weeks. The composting of separated solid swine manure amended with sawdust and manure compost biofiltration system were evaluated to determine the turning frequency type that would be adequate for the rate of decomposition and compost odour reduction. The compost odour cleaning was measured based on ammonia gas concentration before and after passing through the manure compost biofilter. The average ammonia odor reduction in the manure compost biofilter was 96.9 % at R1 (no turning), 99.4 % at R2(once a day turning) and 89.0 % at R3(twice a day turning), respectively. The efficiency of ammonia reduction was mainly influenced by the turning frequency.

• Structural Engineering and Mechanics
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• v.34 no.1
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• pp.61-84
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• 2010

Presented in this paper is the behaviour of asymmetric building isolated by the double variable frequency pendulum isolator (DVFPI). The DVFPI is an adoption of single variable frequency pendulum isolator (VFPI). The geometry and coefficient of friction of top and bottom sliding surfaces can be unequal. The governing equations of motion of the building-isolation system are derived and solved in incremental form. The analysis duly considers the interaction of frictional forces in the two principal directions developed at each sliding surface of the DVFPI. In order to investigate the behaviour of the base isolation using the DVFPI, the coupled lateral-torsional response is obtained under different parametric variations for a set of six far-fault earthquake ground motions and criterion to optimize its performance is proposed. Further, influences of the initial time period, coefficient of friction and frequency variation factors at the two sliding surfaces are investigated. The numerical results of the extensive parametric study help in understanding the torsional behaviour of the structure isolated with the double sliding surfaces as in the DVFPI. It is found that the performance of the DVFPI can be optimized by designing the top sliding surface initially softer and smoother relative to the bottom one.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.99-109
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• 2009

In this study, often the spatial distribution of precipitation was analyzed using the quantile with regional frequency analysis and spatial analysis to find out the detail distribution of extreme precipitation for preventing the disaster in the region of Gangwon. The hourly precipitation data of 66 stations in Gangwon were used. As the results of regional frequency analysis, it shows that the generalized logistic (GLO) distribution is the best for the region of Gangwon. As the results of spatial analysis, the quaniles have high vaules nearby Seolakdong, Daegwallyeong and Cheongil as the duration of precipitation increase, and the change of spatial distribution occurs severely according to the duration of precipitation. The spatial characteristics of precipitation appears clearly as the return period of quantile increases. As the results of the spatial distribution of precipitation in Gangwon heavy quantiles usually are appeared in Yongdong, and the spatial distributions of quantile in Yongseo are various according to the duration and the return period of quantile. Therefore, to estimate more accurate quantiles in Gangwon, various geographical and weather conditions are considered additionally for the regional precipitation frequency analysis.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.468-472
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• 2007

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.235-242
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• 1999

Wave which propagate from the offshore cause transformation of diffraction, refraction, and reflection etc. in coming in the coastal by depth change. Especially, Wave strongly show the charcateristics of rancom wave in the coastal zone. Developed wave model until a recent date analysed regular waves with height and period equal to those of the significant wave, In case of Monochromatic wave, it can be analysed fine in the offshore, but differ from in coastal zone. In this study, form of governing equation is parabolic mild slope equation. This model calculated random wave for using frequency spectrum and directional spectrum from input data condition of wave. This model is applied to Vincent shoal and compared with laboratory experimental data. The results agreed well with laboratory data.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.631-636
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• 1987

The design of ultrasonic transducer energy processing systems requires highly reliable command featuring mechanical frequency tracking and constant velocity control of the ultrasonic transducer with an acoustic load. This paper presents a new conceptional instantaneous current resultant control base high-frequency inverter using self turn-off devices driving an electrostrictive ultrasonic transducer system and its optimum control technique, which is implemented by feed-back of the ultrasonic transducer applied voltage and instantaneous velocity of the transducer vibrating system through a Phase-Locked-Loop control scheme. The feedback voltage corresponding to instantaneous velocity is averaged over a half-period with respect to constant amplitude/constant velocity control strategy. Described are the theory of this signal detection technique and the experimental set-up.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.141-148
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• 2008

An utility voltage information, including the frequency, phase angle and amplitude is very important in many industrial systems. The grid-connected photovoltaic system in the limelight as alternative energy needs utility voltage information such as frequency, phase angle and magnitude to connect the grid-line. In this paper, it proposes the instantaneous phase-tracking in PLL that uses the frequency from the utility voltage as a sync signal and locks the phase with compensation for phase difference from DPT algorithm. It also proposes not only DFT algorithm execution by every sample not by one period, but also phase-tracking method in a wide range of frequency not a fixed one. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the experiment.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.4
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• pp.300-304
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• 2019

This study was conducted to examine the oocyte recovery efficiency through having an OPU session once and twice a week. Also, the oocyte recovery efficiency was examined by using OPU after two and three months of rest period. Six cows were used for oocytes collection and were randomly divided into two groups. In experiment 1, OPU sessions were conducted once and twice a week to collect oocytes. The collected oocytes between once and twice OPU groups were classified into four groups (grade 1, 2, 3 and 4) according to the quality of cumulus cells and ooplasm. Based on the result, the percentage of collected oocytes per aspirated follicle number was similar between once and twice OPU session groups (65.5 ± 1.9 and 68.7 ± 1.4 vs.). However, the percentage of grade 1 oocytes from the twice OPU session group was significantly high compared with that of the once a week OPU session group (25.3 ± 0.9 and 32.5 ± 1.2% vs. once and twice session group, respectively, p < 0.05). In experiment 2, the group with three months of rest period tended to have a high percentage of collected oocyte compared with the group with two months of rest period (64.6 and 70.9% vs. 2 and 3 months rest group, respectively, p = 0.62). The percentage of grade 4 in the group with three months of rest period was significantly low compared with the group with two months of rest period group (27.3 and 36.5% vs. two and three months rest group, respectively, p = 0.05). In conclusion, twice a week OPU session is suitable for collection of high quality oocytes by using OPU, and three months of rest period is needed for the recovery of oocyte quality of a donor cow.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.4
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• pp.1-11
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• 2006

A citation-based method of estimating the life span of a patented technology is proposed In this study. The suggested framework Includes : (1) estimation of citation frequency of an individual patent within a technology group. (2) calculation of a mutual citation frequency between citing patent and cited patents, (3) calculation of the period for cited patents from the year of registration to the year of being cited most recently and (4) description for technology group using descriptive statistics such as mean, median, mode, etc. The framework suggested in this study was applied to the US patent data between 1976 and 2004 for 5 communications areas.

• International Journal of Reliability and Applications
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• v.9 no.2
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• pp.141-152
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• 2008

This paper presents equations, which can be used to evaluate the failure frequency and the failure rate of a two identical component parallel redundant system in which each component can operate in its wear out period, and the failure rate of each component is exponential power distribution. The optimum maintenance interval for a two identical component parallel redundant system can be obtained using these equations. The proposed approach is presented and illustrated using several numerical examples. The optimum maintenance interval for each component in a two identical parallel redundant system will depend on factors such as: failure rate, repair and maintenance times of each component in the parallel redundant systems.