• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.97-97
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• 2004

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.309-314
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• 2009

The unpredicted worldwide oil price makes the energy efficiency technology be more importance than any other period. The small cogeneration system is one of the most representative technology among the energy efficiency technologies, and the Stirling engine cogeneration system has been concerned and investigated due to the preferable characteristics - low toxic emission, low noise and vibration level, and the various form of fuel. A tiny, 1kW of electrical output, gas fueled Stirling engine cogeneration system was investigated. The electrical efficiency and thermal efficiency of the system were measured. The experiment was executed at an independent Stirling engine mode, independent secondary burner mode, and the combined mode. Part load characteristics of the Stirling engine cogeneration system were investigated also. With the efficiency characteristics, the $O_2$ and NOx emission characteristics were measured.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.119-122
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• 2002

In general, Liquid Injection Thrust Vector Control(LITVC) is accomplished by injecting a liquid into the supersonic exhaust flow through holes in the wall of the propulsion nozzle. This injection flow field is highly complicated and detailed flow physics associated with the secondary flow injection should be known far the practical design and use of the LITVC system. The present study aims at understanding the LTTVC flow field and obtaining fundamental design parameters for LITVC. The experimentations were performed in a supersonic blow-down wind tunnel. Compressed, dry air was used for both the main exhaust and injection flows but the pressures of these two flows were controlled independently. The location of the injection holes was changed and the pressures of the two streams were also changed between 2.0 and 15.0 bar. The effectiveness of LITVC was discussed in details using the results of the pressure measurements and flow visualizations

• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.12-21
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• 2015

Due to the influence of Han-la Mountain which is located at the center of Jeju Island, a radar blind sector has been appearing in the south-east, low-altitude area of Jeju Island. Thus, the region is perilous for aircraft using surveillance in this area with the existing radar equipment that is currently available. In addition, as the popularity for domestic leisure aviation is on the rise, the safety in low-altitude area should be guaranteed. Where not only IFR flights but also VFR flights are mainly used. Therefore, immediate measures to the present state of radar blind sector in Jeju Island should be taken into serious account. Regarding the circumstances, this study's purpose is to help secure the aviation safety in Jeju region by analyzing the current air traffic surveillance system in Jeju Island and comprehending its vulnerable factors. Moreover, this study compares secondary radar surveillance system, ADS-B and MLAT(Multilateration) system with factors based on the guidance materials from ICAO Asia and Pacific region office to suggests an adequate surveillance technology considering the regional characteristics of Jeju.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.827-829
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• 2015

This paper presents process of the UE obtains the cell system information in order to achieve communication with the LTE network on the LTE. This paper deals with the process of extracting MIB(Master Information Block) cell system information in LTE. To study the 3GPP LTE standard spec series 36.200 and 36.300, the simulation is implemented to extract the MIB in MATLAB program. The simulation process is divided into three parts. It consisted of a part that extracts the PSS, SSS and MIB. Called a cell search process for detecting the PSS and SSS, the process is to be done in order to extract only the cell system information. The simulation program is verified based on the signal captured from the real Air.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.831-838
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• 2004

A fluid-solid conjugate solver has been newly developed and applied to an actual engine disk system. Most of the currently available conjugate solvers lack the special thermal modeling for turbomachinery disk system applications. In the present new code, these special models are implemented to expand the applicability of the conjugate method and to reduce the required computational resources. Most of the conjugate analysis work so far are limited to the axisymmetric framework. However, the actual disk system includes several non-axisymmetric components which inevitably affect the local heat transfer phenomena. Also the previous work devoted to this area usually concentrate their efforts on the steady-state thermal field, although the one in the transient condition is more critical to the engine components. This paper presents full 3D conjugate analysis of a single stage high pressure turbine rotor-stator disk system to assess the three-dimensional effects (Fig. 1). The analysis is carried out not only in the steady-state but also in the engine accelerating transient condition. The predicted temperatures shows good agreement with measured data.

• Journal of Korean Neurosurgical Society
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• v.30 no.1
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• pp.81-84
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• 2001

Pneumocephalus is exceedingly rare in the absence of trauma or recent surgery. It is most commonly seen after severe head injury, with disruption of the dura and subsequent cerebrospinal fluid leakage. Intracranial air has also been reported as a complication of shunting. This may be secondary to intermittent shunt failure or a persistent communication between the extracranial and intracranial space that permits the entrance of air. In the present case, air appeared to enter the ventricular system through the fistula that connected the frontal sinus. This air replaced the CSF being drained into the peritoneal cavity by the shunt. The decrease of intracranial pressure after a shunt might play a role in causing pneumocephalus. We report a case of tension pneumocephalus after shunting for hydrocephalus as a life-threatning complication.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.500-505
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• 2005

This paper introduces an experimental study for the noise characteristics and reduction of a ventilating fan system. For the purpose of noise reduction of it, an absorptive duct silencer filled with a glass fiber has been conventionally utilized. However, a glass fiber has some disadvantages like hygiene and secondary pollution problems. In order to overcome these problems, in this paper, a perforated duct silencer has been applied to the ventilating fan system. For the designing of a perforated duct silencer, the transmission losses for various perforated panel systems are measured and compared with their sound absorption performances.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.2
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• pp.133-140
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• 2009

In order to examine the effects of micrometeorological and climatological influences on urban scale particulate air pollutants observed in Busan, power spectrum analysis was applied to the observed particulate matter with aerodynamic diameter ${\le}10{\mu}m$ ($PM_{10}$) for the period from 1991 to 2006. Power spectrum analysis has been employed to the daily mean $PM_{10}$ concentrations obtained at 13 sites to identify different scales of periodicities of $PM_{10}$ concentrations. The results show that, aside from the typical and well-known periodicities such as diurnal and annual variations caused by anthropogenic emission influences, another two significant peaks of power spectrum density were identified: 21 day and $3{\sim}4$ year of periodicities. Cospectrum analysis indicates that the intraseasonal 21 day periodicity are found to be negatively correlated with wind speed and surface pressure but shows consistently positive with relative humidity and temperature. This result implied that 21 day periodicity is presumably relevant to the secondary aerosol formation processes through the photochemical reaction that can be subsequently resulted from hygroscopic characteristics of aerosol formation. However, the interannual $3{\sim}4$ year of periodicity is found to have positive correlation with pressure, and negative with temperature and relative humidity, which is rather consistent with both characteristics of air mass during the Asian dust event and the occurrence frequency of Asian dust whose periodicities have been recorded inter-annually over the Korean peninsula.