• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.10a
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• pp.82-85
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• 1995

Magnetic-electrolytic-abrasive polishign(MEAP) systemwas newly developed and the finishing characteristics of Cr-coated roller was analyzed. The paper describes the operational principle of MEAP system and magnetic field effect on the MEAP process by experimental results. The finishing characteristics and optimal finishing condition for Cr-coated roller were experimented and analyzed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.137-142
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• 1996

Magnetic-electrolytic-abrasive polishing system(MEAPS) was developed for machining national standard electrode and its finishing characteristics was analyzed. The paper describes the operational principle of MEAP system by experimental results. The finishing characteristics and optimal finishing condition for national standard electrodes were experimented and analyzed. As a result, MEAPS can improve straightness as well as surface roughness.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.85-105
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• 2016

In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

• Journal of Environmental Health Sciences
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• v.29 no.4
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• pp.4-9
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• 2003

Biofiltration can effectively remove both organic and inorganic air pollution compounds from both industrial and public sources. However, for the optimal biofiltration performance, it is necessary to gain a better understanding of the inner environment and destruction mechanisms within a biofilter. The effects of operational factors on removal efficiency was studied. Generally, removal efficiency decreases as the loading rate increases. Temperature, as one of the key factors that affect biofiltration design and performance, was also investigated. Conceptually, the biofilter reactor of this paper was divided into five different consecutive stages. The more ethylbenzene COD degraded at each stage, the higher the temperature increases observed compared to the temperatures of the previous stages. It was observed that for every 1 kg of ethylbenzene COD degraded per cubic meter of biofilter media, there was generally a 0.41$^{\circ}C$ increase in the temperature of that stage.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1756-1758
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• 1996

In order to optimize the operational characteristics of single elliptical pulsed Nd:YAG laser designed and fabricator compactly, it is very important to design the resonator shape and the PFN(Pulse Forming Network) suitably. We have been shown that the EMTP(Electro-Magnetic Transient Program) simulation. was used effectively in designing PFN. And Next, we have been compared current pulse width, laser beam profile and damping parameter with laser output energy. In this paper, we have suggested the optimalization of PFN design and the best operational condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.66-71
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• 2005

In this study the regression rate of hybrid rocket fuel has been investigated by two methods. First method is to use swirl injectors for enhancement of regression rate. And second method is the modification of the helical grain deriving improvement of combustion area and generating swirl flow. Tests have been done with PMMA and gaseous oxygen. In this paper the incline angle of the helical grain was varied to find the optimal condition to obtain the max regression rate for a given operational condition.

• Journal of Environmental Science International
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• v.31 no.4
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• pp.295-309
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• 2022

The purpose of this study was to evaluate the operational characteristics of wastewater treatment using Sequencing Batch Reactor (SBR) with Aerobic Granular Sludge (AGS) separator in the pilot plant. Pilot plant experiments were conducted using SBR with AGS separator and pollution removal efficiencies were evaluated based on the operational condition and surface properties of AGS. The results of the operation on water quality of the effluent showed that the average concentration of total organic carbon, suspended solids, nitrogen, and phosphorus was 6.89 mg/L, 7.33 mg/L, 7.33 mg/L, and 0.2 mg/L, respectively. All these concentrations complied the effluent standard in Korea. The concentration of mixed liquor suspended solid (MLSS) fluctuated, but the AGS/MLSS ratio was constant at 86.5±1.3%. Although the AGS/MLSS ratio was constant, sludge volume index improved. These results suggested that the particle discharged fine sludge and increased the AGS praticle size in the AGS. Optical microscopy revealed the presence of dense AGS at the end of the operation, and particles of > 0.6 mm were found. Compared to those of belt-type AGS separator, the required area and power consumption of the hydrocyclone-type AGS separator were reduced by 27.5% and 83.8%, respectively.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.349-357
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• 1989

Uncooked starch can be effectively saccharified in an enzyme reaction system containing attrition-milling media. To develope the high efficiency bioattritor, an agitated bead type bioreactor was constructed, and its effectiveness was evaluated. The optimal operation condition of bioattritor was found to be 300 g glass bead/L, 200 rpm, standard type impeller for 220 g/L of uncooked corn starch. The torque under the various operational conditions were also measured. The interrelation-ship between energy consumption for agitation of attrition-milling media and enhanced extent of saccharification of uncooked starch was evaluated, Power consumption was measured to be around 1.53 watt/L under the optimal operation condition. The attrition coupled enzyme reaction system is identified to tie a very excellent energy saying process for saccharification of uncooked starch, and seems to have a bright prospect of industrial application.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.6
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• pp.605-615
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• 2017

Efficient simultaneous reduction conditions for $NO_x$ and $NH_3$-slip was investigated in SCR (Selective Catalytic Reduction) process with load variation by applying dual catalysts (SCR catalyst, $NH_3$ decomposition catalyst) system. $N_2O$ formation characteristics were analyzed to look into possible undesirable reaction pathways. In the experiments of catalyst characteristics, various operational variables were tested for the combined catalytic system, such as $NH_3/NO_x$ ratio, temperature, oxygen concentration and $H_2O$. The reaction characteristics of $NO_x$, $NH_3$ and $N_2O$ were analyzed and optimal conditions could be evaluated for the combustion facility with varied load. In terms of $NO_x/NH_3$ simultaneous reduction and $N_2O$ formation suppression, optimal condition was considered NSR 1.2 and temperature $300^{\circ}C$. At this operational condition, $NO_x$ conversion was 98%, $NH_3$ reduction efficiency was 95%, generated $N_2O$ concentration 9.5 ppm with inlet $NO_x$ concentration of 100 ppm. In $NH_3-SCR$ process with $NH_3$ decomposition catalyst, $NO_x$ and $NH_3$ can be considered to be reduced simultaneously at limited conditions. The results of this study may be utilized as basic data at facilities requiring simultaneous $NO_x$ and $NH_3$ reduction for facilities with load variation.

• Journal of the military operations research society of Korea
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• v.17 no.1
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• pp.61-83
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• 1991

There has been a great deal of research dealing with the optimal replacement of stochastically deteriorating equipment and research in queueing systems with a finite calling population. However. there has been a lack of research which combines these two areas to deal with optimal replacement for a fixed number of machines and a limited number of repairmen. In this research, an optimal control policy for replacement involving two machines and one repairman is developed by investigating a class of age replacement policies in the context of controlling a G/M/1 queueing system with a finite calling population. The control policy to be imposed on this problem is an age-dependent control policy, described by the control limit $t^{\ast}$. The control limit is operational only when the repairman is idle; that is. if both machines are working, as soon as a machine reaches the age $t^{\ast}$ it is taken out of service for replacememt. We obtain the ${\epsilon}$-optimal control age which will minimize the long-run average system cost. An algorithm is developed that is applicable to general failure time distributions and cost functions. The algorithm does not require the condition of unimodality for implementation.