• Laser Solutions
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• v.7 no.3
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• pp.11-24
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• 2004

In automotive industry, light weight vehicle is one of issues because of the air pollution and the protection of environment. Therefore, automotive manufacturers have tried to apply light materials such as aluminum to car body. Aluminum welding using laser has some advantages high energy density and high productivity. It is very important to understand behavior of plasma and keyhole in order to improve weld quality and monitor the weld state. In this study, spectral analysis was carried out to verify the spectrum for plasma which is generated in laser welding of A 6000 aluminum alloy. Two photodiodes which cover the range of plasma wavelength was used to measure light emission during laser welding according to assist gas flow rate and welding speed. Analysis of relationship between sensor signals of welding variables and formation of keyhole and plasma is performed. To determine the level of significance, analysis of variation (ANOVA) was carried out.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.149-155
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• 2005

The $ACP^1$ is under development for effective management of spent fuel by converting $UO_2$ into U-metal. For demonstration of this process, $\alpha-\gamma$ type new hotcell was built in the $IMEF^2$ basement. To secure against radiation hazard, this facility needs radiation monitoring system which will observe the entire operating area before the hotcell and service area at back of it. This system consists of 7 parts; Area Monitor for $\gamma$-ray, Room Air Monitor for particulate and iodine in both area, Hotcell Monitor for hotcell inside high radiation and rear door interlock, Duct Monitor for particulate of outlet ventilation, Iodine Monitor for iodine of outlet duct, CCTV for watching workers and material movement, Server for management of whole monitoring system. After installation and test of this, radiation monitoring system will be expected to assist the successful ACP demonstration.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.174-182
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• 2007

Fuel reforming technology for the fuel cell vehicles could be applied to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this study, syngas was added to a gasoline engine to improve combustion stability and exhaust emissions of idle state. Syngas fraction is varied to 0%, 50%, 100% with various ignition timing and excess air ratio. Combustion stability, exhaust emissions, fuel consumption and exhaust gas temperature were measured to investigate the effects of syngas addition on idle performance. Results showed that syngas has ability to widely extend lean operation limit and ignition retard range with dramatical reduction of engine out emissions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.27-28
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• 2019

Recently, a bed company detected a radon more than Red Politics and became a hot topic of conversation. This has led to increased interest in radon, and a number of free-of-charge bodies have also been established to recognize the dangers of radon. In addition, the Korean Institute of Geological and Resource Research is planning to assist the installation of radon alarm systems in 10,000 households nationwide, free of charge. Since radon is a colorless, odorless and tasteless gas that causes lung cancer, it aims to reduce lung cancer incidence by absorbing radon using bamboo activated carbon as a way to reduce it. Due to the use of bamboo activated carbon, radon concentration per hour tends to decrease as substitution rate increases, and table flow tends to decrease as substitution rate increases. Through this experiment, 30% of the replacement rate of bamboo activated carbon is judged to be the most suitable replacement rate.

• Journal of the Korean Home Economics Association
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• v.39 no.6
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• pp.109-122
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• 2001

This study was performed to identify the roles of residents for the environmentally sound and sustainable development, taco-polis(kologisches Bauen), eco-village and Symbiotic Housing. These buildings will achieve energy efficiency through design strategies such as passive solar heating system, natural cooling and day lighting. Their infrastructure will feature parking on the periphery, extensive pedestrian paths, outdoor ground lights that preserve stellar visibility, and environmentally sensitive technologies such as low writer use fixtures. And they will restore biodiversity while protecting the wildlife, wetlands, forests, soil, air and water. Their houses wile be designed to support home-based occupations, offering high-speed Internet access and other options to promote a localized, sustainable economy. To support and encourage the evolution of sustainable settlements, it is necessary to prepare constructing the physical facilities and the social functions relating with residents. The roles of residents are important to provide a high Quality lifestyle and to integrate a supportive social environment with a low-impact way of life. This study concluded the four main roles of residents for the sustainable of Eco-polis and Ecovillage. 1. Residents assist transition towards a sustainable society as eco-conscious consumers in the planning stage. 2. Residents live in a ecological way for the sustainable ecovillage. 3. Residents exchange information and education for increasing the community glue as a communication network. 4. Residents support and transmit their cultural vitality and tradition for the next generation. So, users are expected to encourage resident's participation in the planning, design, ongoing management and maintenance of the sustainable ecovillage.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.569-576
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• 2007

Ventricular Assist Device(VAD) has switched its goal from a short-tenn use for bridge-to-transplantation to a long-tenn use for destination therapy, With this goal, the importance of long-tenn reliability gets more interests and importances, H-VAD is an portable extracorporeal biventricular assist device, and adopts an electro-pneumatic driving mechanism. The pneumatic pressure to pump out blood is generated with compression of bellows, and is transmitted in a closed pneumatic circuit through a pneumatic line. The existing pneumatic VAD adopts a air compressor which can generate stable pressures but has defects such as a noise and a size problem. Thus, it is not suitable for being used as a portable device, These problems are covered with adopting a closed pneumatic circuit mechanism with a bellows which has a small size and small noise generation, but it has defects that improper pneumatic setting causes a failure of adequate flow generation. In this study, the pneumatic pressure regulation system is developed to cover these defects of a bellows-type pneumatic VAD. The optimal pneumatic pressure conditions according to various afterload conditions for an optimal flow rate were investigated and the afterload estimation algorithm was developed, The final pneumatic regulation system estimates a current afterload and regulate the pneumatic pressure to the optimal point at a given afterload condition. The afterload estimation algorithm showed a sufficient performance that the standard deviation of error is 8.8 mmHg, The pneumatic pressure regulation system showed a sufficient performance that the flow rate was stably governed to various afterload conditions. In a further study, if a additional sensor such as ultrasonic sensor is developed to monitor the direct movement of diaphragm in a blood pump part, the reliability would be greatly increased. Moreover, if the afterload estimation algorithm gets more accuracy, it would be also helpful to monitor the hemodynamic condition of patients.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.183-190
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• 2006

An experimental study was conducted to evaluate the effect of freezing-thawing and air pollutants on the weathering of $TiO_2$ loaded granite. And the granite was coated with $TiO_2$ catalyst and tested. After freezing-thawing and air pollutants experiments the mineral compositions of the granite surface were lower then that of the fresh granite. Density of the weathered granite was steadily decreased from $2.60g/cm^3\;to\;2.55{\sim}2.56g/cm^3$, but absorption ratio and porosity were slightly increased. From these results, it was expected that granite could be weathered by freezing-thawing md air pollutants. In the case of $TiO_2$ was coated to the granite, the compressive strength and absorption ratio were slightly enhanced compared to the $TiO_2$ non-coated granite. Therefore, the $TiO_2$ coating method tested in this study considered to be a viable method to assist in the conservation of granite from environmental contaminants.

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.825-831
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• 2007

An elbow orthosis with a pneumatic rubber actuator has been developed to assist and enhance upper limb movements and has been examined for the effectiveness. The effectiveness of the elbow orthosis was examined by comparing muscular activities during alternate dumbbell curl exercises with and without the orthosis. The subjects participated in the experiment were younger adults in their twenties. The subjects were instructed to perform dumbbell curl motion in a sitting position with and without orthosis in turn and a dynamometer was used to measure elbow joint torque outputs in an isovelocity mode. The measurements were done with four various dumbbell loads: 0 kg, 1 kg, 3 kg, and 5 kg. The orthosis was pneumatically actuated and controlled in a passive mode. The most comfortable air pressure to the pneumatic actuator was determined to be 0.294MPa. Electromyography(EMG) was also measured during curl exercises. The muscles of interest were biceps brachii(BB), triceps brachii(TB), brachioradialis(Bo), and flexor carpi ulnaris(FCU) in the upper limbs. The experimental results showed that the muscular activities themselves significantly reduced with elbow orthosis on in performing similar activities without orthosis. As a result of this experiment, the effectiveness of the developed upper limb orthosis was confirmed and the level of assistance was quantified.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.436-444
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• 2018

The purpose of this research is to assess the efficiency of the airline's route. The revenue source of low cost airline carriers is not various unlike regular airline carriers, because they are operating only domestic and international flights for a country of close proximity. In particular, domestic low-cost airlines in Korea can't provide cargo transport services but rely on passengers and additional services to generate profits. Therefore, it is absolutely important to maintain a low cost and effective passenger transport line. This study will suggest the way to improve efficiency of route operated by low-cost airlines. Analysis method is DEA. The input parameters and output results were selected by existing research. Based on the results of this study, it will be able to assist establishing routes and selling strategies of the low-cost airlines.

• KSBB Journal
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• v.19 no.3
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• pp.236-240
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• 2004

Korean wastewaters have higher nitrogen concentrations than typical wastewaters of other countries. Most treatment processes such as activated sludge processes will need to supplement extra carbon sources for a complete removal of remaining nitrogen after the initial wastewater treatment, Because of these difficult matters, we have searched wastewater treatment methods that require no additional carbon sources. Wastewater treatment by microalgae in photobioreactors, using a green eukaryotic microalgae, Chlorella kessleri, showed a promising results and thus was selected to study further. This system is not intended to replace the conventional system but is to assist the existing biological treatment systems as a supplemental nitrogen removal process. Thus the secondary treated livestock wastewater was tested. Column type photobioreactors developed in our laboratory were used. When aerated with 5% CO$_2$ balanced with air at 1 vvm and illuminated at 100 ${\mu}$mol/㎡/s under 25$^{\circ}C$ and PH 7-8 by CO$_2$ buffering effect, the maximum nitrogen removal rate was 2.6 mg/L/hr. The results confirmed a possibility of microalgal wastewater treatment system as a secondary system to remove extra nitrogen sources. Based on these experimental results, the size of the optimal microalgal wastewater system was calculated. For the wastewater whose initial nitrogen concentration of 150 mg/L, the optimal batch system was found to be a 2 stage system with a combined retention time of 4.6 day. From the continuous experiments, nitrogen removal rates were examined under different dilution rates and 2 stage system was also found to be the optimal system. The combined retention time for the continuous system was 3.5 days. It is expected that conventional biological wastewater treatment systems followed by microalgal systems would reliably decrease the nitrogen concentration below the government criteria even for the livestock wastewater with low C/N ratio.