• 전기의세계
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• v.22 no.6
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• pp.33-51
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• 1973

To lower the earth resistance shall be one of the most effective method for the prevention of lightening damage on power transmission line. In this report, in order to investigate various characteristic necessary to lowering the earth resistance, the following experiments have been made at 154KV U1San-PoHang T/L, 154KV YoSu-SoonChun T/L and so on. 1. Measurement of Earth specific resistance, 2. Efficiency of Earthing of concrete foundation for steel structure., 3. Efficiency of Earthing with counter poise., 4. Compound impulse test with foundation of steel structure and counter poise. With the above investigate a guidance have been prepared for the effective work-performance of steel structure.

• Nuclear Engineering and Technology
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• v.47 no.4
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• pp.500-511
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• 2015

In this study, the natural frequencies of the perforated square plate with a square penetration pattern are obtained as a function of ligament efficiency using the commercial finite-element analysis code ANSYS. In addition, they are used to extract the effective modulus of elasticity under an assumption of a constant Poisson's ratio. The effective modulus of elasticity of the fully perforated square plate is applied to the modal analysis of a partially perforated square plate using a homogeneous finite-element analysis model. The natural frequencies and the corresponding mode shapes of the homogeneous model are compared with the results of the detailed finite-element analysis model of the partially perforated square plate to check the validity of the effective modulus of elasticity. In addition, the theoretical method to calculate the natural frequencies of a partially perforated square plate with fixed edges is suggested according to the Rayleigh-Ritz method.

• Culinary science and hospitality research
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• v.16 no.2
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• pp.49-63
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• 2010

The purpose of this study is to investigate how menu management effect on job efficiency at a hotel restaurant. Target standardization amount is needed to set for effective menu management to give quality menu toward customers to do that bring effective job efficiency. The survey is conducted to employees who are working at hotel restaurant. To verify the hypotheses, set this study up frequency analysis, reliability analysis, factor analysis, and linear regression analysis. The collected questionnaires were analyzed through statistical package SPSS WIN 12.0. Moreover, adjusting regression analysis using multiplying matrix was carried to obtain the results of effectiveness. The results show that menu management is required to apply the target amount of standardization in order to increase the job efficiency. At a menu planning phase, managers are expected to compose menu after having full consultation with employees. During the process, the target standardization amount can play a key role to improve job efficiency. Conclusively, to get effective customer service performance, it is necessary to set the target amount standardization if you are considering a trend and taste of customers who should be kept being adjusted or supplemented in line with a trend.

• ETRI Journal
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• v.26 no.3
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• pp.277-280
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• 2004

The distributions of electric field and induced second-order nonlinearity are analyzed in the periodic poling of optical fibers. A quasi-phase matching efficiency for the induced nonlinearity is calculated in terms of both the electrode separation distance between the applied voltage and generalized electrode width for the periodic poling. Our analysis of the quasi-phase matching efficiency implies that the conversion efficiency can be enhanced through adjusting the separation distance, and the electrode width can be maximized if the electrode width is optimized.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.195-201
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• 2006

The operational characteristics of anaerobic bioreactors in treating swine wastewater were evaluated upto hydraulic retention time (HRT) of 1 day and organic loading rate (OLR) of $5.1kg-COD/m^3{\cdot}d$ for 200 days. The bioreactors were effective in treating swine wastewaters with COD removal efficiency of $78.9{\sim}81.5%$ and biogas generation of $0.39{\sim}0.59m^3/kg-COD_r$ at OLR of $1.1{\sim}2.2kg-COD/m^3{\cdot}d$. The two-stage ASBF anaerobic bioreactors was effective in treating different characteristics of swine wastewaters since they showed high and stable COD removal efficiency at high OLR due to effective retention of biomass by media and staging. The effects of ammonia on anaerobic digestion were investigated by operating two-stage ASBF reactors using swine wastewaters as influent without and with ammonia removal at HRT of $1{\sim}2$ days and OLR of $2.2{\sim}9.6kg-COD/m^3{\cdot}d$ for 250 days. The COD removal efficiency and biogas generation of two-stage ASBF reactors was decreased by increasing influent ammonia concentrations to 1,580 mg (T-N)/L with increasing OLR to $6.3kg-COD/m^3{\cdot}d$, while those were increased by maintaining influent ammonia concentrations below 340 mg (T-N)/L by MAP precipitation with increasing OLR to $9.6kg-COD/m^3{\cdot}d$. Initial inhibition of ammonia on anaerobic processes was observed at a concentration of 760 mg (T-N)/L and the COD removal efficiency and biogas generation dropped to 1/2 at ammonia concentration ranges of $1,540{\sim}1,870mg$ (T-N)/L. It is essential to remove ammonia in swine wastewaters to an initial inhibition level before anaerobic processes for the effective removal of COD.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.11a
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• pp.31-37
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• 2006

The objective of this research is to select the most effective technique from task related techniques(motion & time study, job redesign, physical environment improvement) for improving work efficiency in shipbuilding enterprise. This study consists of several principal steps. The first step is to design critical criteria in evaluating work efficiency in shipbuilding enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP(Analytic Hierarchy Process)structure using the critical criteria, sub-criteria and techniques from task related techniques. The fourth step is to develop the pairwise comparison matrix by each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique from task related techniques using AHP analysis. The result of AHP analysis has shown clear difference in priority among task related techniques in terms of work efficiency of the shipbuilding enterprise: The reduction of normal time has more importance than the reduction of allowance time, motion & time study techniques are most important for the reduction of normal time, physical environment improvement is most important for the reduction of allowance time as well.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.1-11
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• 2004

In order to recognize thermal efficiency and power improvement in case that diesel cycle is turned into diesel-atkinson cycle, the fuel-air diesel-atkinson cycle considered gas exchange process is analyzed non-dimensionally and thermodynamically. As a result, in case of diesel-atkinson cycle, as expansion ratio is increased, thermal efficiency and mean effective pressure is increased and it has maximum value at Rec=1. When diesel cycle is turned into diesel-atkinson cycle by late intake valve closing timing, thermal efficiency and power is decreased because of the decline of effective compression ratio and intake airflow, but it could be compensated by increase of compression ratio or super-charged. In case compression ratio is compensated, Rec appears 1 around 100$^{\circ}$ ABDC, and it is expected that thermal efficiency is enhanced by 14.3% compared with conventional diesel cycle. In case compression ratio and intake airflow are compensated simultaneously, super-charged pressure is demanded 2.06bar at Rec=1 and it is more efficient when only compression ratio is compensated in the view point of thermal efficiency.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.110-124
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• 2007

In this study, the control efficiency of odorous compounds was measured from diverse control process units of 14 individual companies located within the Ban-Wall industrial complex of Ansan city, Korea (January to July 2005), To quantify the control efficiency levels of major odorous compounds, we collected odor samples from both the front and rear side of 17 control process units ($N=17{\times}2=34$). If the control efficiency is compared for each of 32 compounds between different process units, wet scrubber (WS) was found to be the most effective unit in terms of the sum of pollutants showing the positive control signals. Although the WS system shows generally a good control pattern for VOC, it is not the case for most index odorous pollutants; only 3 out of 12 index compounds were found to show positive control efficiencies. The results of the study also indicated that the control efficiency differ greatly between different industrial sectors and/or control process types. In the case of leather industry, carbonyl compounds were found to exhibit the highest control efficiency with its values varying from 19 to 90%. On the other hand, in the case of metal production sector, VOC recorded the maximum control efficiency with values varying from 18 to 79%. According to this study, most air pollution control facilities operated in most companies show fairly poor control efficiencies for most malodor compounds. Hence, to obtain best control efficiency of odorous pollutant emission, acquisition of better information on source characteristics and establishment of effective control technologies are highly demanding.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.24-30
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• 1999

A biological filter for treatment of toluene among volatile organic compounds was studied. The investigation was conducted using specially built stainless steel columns packed with granular activated carbon and cold for removal of toluene. The G.A. and mold as filter material was also coated with Pseudomonas putida microorganisms.The biofilter unit was operated in the condition of moisture content vairation at gas loading rate of 12.5 l/min. Gaseous toluene taken from tedlar bag was analyzed by the use of G.C equipped with F.I.d detector. The removal efficiency of gaseous toluene was 95% at average inlet concentration of 950 ppm during bio-degradation operating condition. Effective removal efficiency was obtained with moisture content 27.5% at activated carbon and 32% at mold in this study. The effective operating condition were obtained with pH 6-8, temperature 28-42℃ for microbial degradation at gas loading rate of 12.5 l/min in packed material.

• Environmental Engineering Research
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• v.13 no.4
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• pp.197-202
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• 2008

This study evaluated the photocatalytic oxidation of BPA using the RPOD reactor under various conditions. This study found that the RPOD was effective for BPA degradation. It could reduce 1 mg/L of BPA by half within 5 min under the optimum conditions. According to the study results, $TiO_2$ coating was important for the BPA oxidation. As the coating thickness increased, the removal efficiency improved. The light source, the light intensity and the drum rotating speed were important for the oxidation. The UV light was more effective for the BPA degradation than the visible light. The removal efficiency improved with increasing intensity. As the drum speed increased, the removal efficiency improved. The maximum speed was 240 rpm in this study. Addition of air and nitrogen was not beneficial for the BPA degradation in this study probably due to enough oxygen in the water.