• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.148-155
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• 2005

In this study, Development of 300,000kcal/hr high velocity Injection burner with fuel multi-stage was performed using experiments. The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is largest access air combustion and the secondary flame is complete combustion zone, where most of fuel bums. Experiments were performed on an industrial scale in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. Comparison of outlet NOx and outlet Temperature under various air rate and primary/ secondary fuel ratio was performed. The test demonstrated that NOx emission con be reduced by 70% in accordance with operating conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.6
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• pp.668-676
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• 2017

A two-dimensional numerical investigation is performed to study the influence of slot width of multi-stage stationary floating overtopping wave energy devices on overtopping flow rate and performance. The hydraulic efficiency based on captured crest energy of different device layouts is compared with that of single-stage device to determine the effect of the geometrical design. The results show optimal trends giving a huge increase in overtopping energy. Plots of efficiency versus the relative slot width show that, for multi-stage devices, the greatest hydraulic efficiency is achieved at an intermediate value of the variable within the parametric range considered, relative slot width of 0.15 and 0.2 depending on design layouts. Moreover, an application of adaptive slot width of multi-stage device is investigated. The numerical results show that the overall hydraulic efficiency of non-adaptive and adaptive slot devices are approximately on par. The effect of adaptive slot width on performance can be negligible.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.262-265
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• 2007

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. The polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV. In the next step, we examine the technique when the dual-polarization data are split into two multi-look Images.

• Korean Management Science Review
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• v.10 no.1
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• pp.127-137
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• 1993

The blocking probabilities of nx64Kb/s multi-slot calls are generally much higher than that of single slot calls. In order to improve these blocking probabilities of multi-slot calls, we propose a scheme which searches the different numbers of time slots for different types of calls. We analyze the performance of our scheme in a double-buffered time-space-time switching network which accommodates multi-slot calls as well as single-slot calls. The proposed method yields the reduced blocking probabilities, the increased traffic handling capacity and teh reduced CPU processing load, compared with those of the conventional methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.281-284
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• 2005

This research is a study on development of section restoration mortar by multi-functional slag aggregate. Compressive strength, flexural strength and other physical properties on five standards are measured to obtain optimal addition rate (of multi-functional aggregate) and to investigate applicability of multi-functional aggregate in developing repair mortar. As the study result, the properties of repair mortar, such as compressive strength and flexural strength etc. are improved by addition of multi-functional aggregate and confirmed reduction effect of air content.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.288-291
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• 2010

Numerical analysis was conducted on thrust vector control using multi-nozzle system. The nozzle using flow valve switch to control mass flow of multi scarfed nozzle to manage thrust was considered. The operating characteristics of scarfed nozzle, thrust component and moment of multi nozzle in terms of mass flow rate were investigated by three dimensional flow simulation.

• Health Communication
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• v.13 no.2
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• pp.103-108
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• 2018

Background: This study was to analyze gender differences in health status, health behaviors and disease prevalence of multi-cultural family in order to contribute to health promotion of them. Methods: This study used raw data from the Korea Community Health Survey(KCHS) which was performed in 2015. Among them, 3,045 multi-cultural family members were included in this study. Data was analyzed using SPSS 21.0 for descriptive statistics, t test, Chi-square test, and Pearson's correlation coefficients. Results: According to gender, depression and subjective health were different in health status. High risk drinking, hypertension, dyslipidemia, arthritis, and obesity prevalence rate were higher in males than females significantly(p<.001). Conclusion: Based on the study results, it is necessary to establish a public health care program to improve health and welfare of multi-cultural families.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.115-121
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• 1996

Multi-axes driving system is more suitable for FMS(Flexible Manufacturing System) compared with a conventional single-azis driving system. It has some merits such as flexibility in operation, improvement of net working rate, maintenance free because of no gear train, etc. However, studies on position synchronous control for high precision in the multi-axes driving system are not enough. In this paper, a new method of position synchronous control is suggested in order to apply to the multi- axes driving system. The proposed method is structured very simply using speed and position controller based on PID control law. Especially, the position controller is designed to keep position error to minimize by controlling either speed of two motors. The effectiveness of the proposed method is successfully confirmed through several experiments.

• Journal of the Korean Institute of Rural Architecture
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• v.3 no.3
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• pp.57-67
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• 2001

The evolution of multi-family housing in Cheongju can be divided by four stages which are a introduction period from 1972 to 1980, a popularization period from 1981 to 1989, a expansion period from 1990 to 1997, and a stagnation period after 1998. In the introduction period, the multi-family housings were mainly low-rise buildings because a government policy which focused on extension of the apartments for the low-income influenced multi-family housing constructions. During the popularization period, the multi-family housings were still low-rise but houses in various sizes were introduced. That was because the Housing Site Developments were started and private companies' participations followed them increasingly. As a result of vigorous participations of private companies and massive developments of housing sites, the multi-family housings in the expansion period started to show constructions of complex and trends of high density and high rising. Finally, in the stagnation period, a rate of the supply of the small houses, whose size was below $60m^2$ of exclusive, area was increased and extreme high-rise apartments emerged. High rising and density were the mainstream of the construction concepts. During this period, the growth of multi-family housing marked low. The reason was that a downturn in economy led private companies to shrink their constructions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.932-941
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• 2004

The objective of this study is to detect the multi-fault of HVAC system using a new pattern classification technique. To classify the effect of single-fault in determining the pattern, supply air temperature, OA-damper, supply fan, and air flowrate were chosen as experimental parameters. The combination of supply temperature, flow rate, supply fan and OA-damper were chosen as multi-fault conditions. Three kinds of patterns were introduced in the analysis of multi-fault problem. To solve multi-fault problem, the new pattern classification technique using residual ratio analysis was introduced to detect the multi-fault as well as single-fault. The residual ratio could diagnose single-fault or multi-fault into several patterns.