• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.215-224
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• 2009

Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.25-25
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• 2009

종래의 위보기 자세에서 용접은 중력이 모재의 표면으로 향하고 있어 용융금속이 중력에 의해 표면방향으로 흘러내리게 되어 용접 실시가 불가능하였다. 이에 Shield Gas Force, Trailing Gas Force 그리고 Ahead Gas Force를 적절히 적용하여 Position Welding에서 중력으로 인해 Molten Metal이 처지는 문제를 극복하여 생산성 향상으로 연결할 수 있음을 선행 실험을 통해 확인하였으나 기존의 C(Convergent)형, CP(Convergent Divergent)형 및 P(Parrallel)형 가스 노즐은 용접조건에 따라 실드 가스의 소모량이 많고, 토출되는 실드가스력이 부족하여 용접시 볼록한 이면 비드 형성을 위한 용융 풀을 효과적으로 제어 할 수 없다. 따라서 본 연구에서는 동일량의 실드 가스 공급시 가스 노즐을 통해 토출되는 실드가스의 소모를 줄이고 실드가스력을 극대화하여 저가의 고생산성을 가진 친 환경 용접기술(Green welding)에 부합하는 CDP(Convergent Divergent Parrallel)형 가스 노즐을 제작하여 기존의 CP형 가스 노즐과 비교 분석하였다. 또한 Overhead Position에서의 비드형상제어와 Flat Position에서 방풍효과를 비교해 보았다. 그 결과 CDP Nozzle은 CP Nozzle보다 동일한 유량에서 풍속은 3.5배, 냉각능력은 1.5배, 가스압력은 6.25배로 우수한 성능을 확인할 수 있었고, Overhead Position에서 가스 유량을 동일하게 하여 용접하였을 때 CP Nozzle의 경우 오목한 이면비드가 나타났지만 CDP Nozzle의 경우 볼록하게 양호한 이면비드 형상이 나타났고, Flat Position에서의 방풍효과 비교실험에서 CDP Nozzle에서는 깊고 균일한 용입을 CP Nozzle에서는 불안정한 용입이 나타났는데 이는 CDP Nozzle의 경우 풍속에 의한 Arc Blow가 적게 발생하여 상대적으로 더 나은 용입을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.629-636
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• 2011

Objective: The aim of this study is developing an elderly automatic showering system by optimizing nozzle position and angle of water injection on ergonomics approach. Background: The elderly living in nursing home or hospital were increased by an aging population. Helping the elderly on showering is so hard. In addition, the existing showering/bathing systems are not effective because shower pattern of the elderly and washed range of nozzle were not considered. Method: Firstly, basic specification were determined by anthropometric approach. Secondly, position of nozzle and angle of water injection were determined through observation of elderly behavior on showering. And, finally, they were optimized by washing test and showering simulation. Results: On showering importance of body parts were able to analysis through observation of elderly behavior. The position of nozzle and angle of water injection was able to optimize by showering simulation. The automatic showering system was developed by considering their results. Conclusion: The most important technology of developing a showering system is the determining position of nozzle and angle of water injection, number of nozzle. It was developed by applying its results through user centered-research. Application: The user centered-research of developing products was able to apply directly to develop automatic bath, showering products etc. Further more it was available to apply senior friendly products.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.325-331
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• 2011

A numerical analysis of reactive flow in a MILD(Moderate and Intense Low oxygen Dilution) combustor is accomplished to elucidate the characteristics of combustion phenomena in the furnace with the change of fuel and air nozzle position and air mass flow rate. For the case with the fuel nozzle located near center position of combustor, the reaction zone started at the fuel nozzle and had inclined shape toward combustor wall when the air mass flow rate was relatively smaller. On the other hand, the end of reaction zone moved toward center of combustor from combustor wall when the air flow rate was relatively larger. For the case with the air nozzle located near center position of combustor, the reaction zone started at the fuel nozzle and had inclined shape toward combustor wall when the air mass flow rate was relatively small, which was similar as the previous case with smaller air mass flow rate. On the other hand, the end of reaction zone moved toward combustor wall when the air flow rate was relatively larger. The maximum temperature increased as the air mass flow rate increasing for both cases, and the concentration of thermal NOx increased also from the previous reason of temperature characteristics. The concentration of NOx for the case with the air nozzle located near center position of combustor was considerably smaller than that for the case with the fuel nozzle located near center position of combustor. From the present study, the case with the air nozzle located near center position of combustor and theoretical air flow rate was the most effective condition for the NOx reduction and perfect combustion.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.45-53
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• 2000

A numerical study is done on the thrust vector control using gaseous secondary injection in the rocket nozzle. A commercial code, PHOENICS, is used to simulate the rocket nozzle flow. A $45^{\circ}-15^{\circ}$ conical nozzle is adopted to do numerical experiments. The flow in a rocket nozzle is assumed a steady, compressible, viscous flow. The exhaust gas of the rocket motor is used as an injectant to control the thrust vector of rocket at the constant rate of secondary injection flow. The injection location which is on the wall of rocket is chosen as a primary numerical variable. Computational results say that if the injection position is too close to nozzle throat, the reflected shock occurs. On the other hand, the more mass flow rate of injection is needed to get enough side thrust when the injection position is moved too far from the throat.

• Journal of the Korean Institute of Gas
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• v.23 no.3
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• pp.1-6
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• 2019

The purpose of the present study is to elucidate flue gas recirculation device for reduction of nitrogen oxides using coanda nozzle without adopting additional power driving fan in a waste incinerator. The characteristics of the exhaust gas recirculation flow rate and the average temperature change at the outlet of the mixed gas were investigated according to the change of air supply nozzle gap and the position of air supply nozzle. When the gap of the air supply nozzle was changed to 3.22, 4.03, and 4.84 mm, the largest recirculation flow ratio, which is the ratio of exhaust gas recirculation flow rate and air supply flow rate, was 2.227 for the case with 3.22 mm and its mean temperature at outlet was $594.8^{\circ}C$. When the position of the air supply nozzle changes to the front position, neck position, and expansion position of the coanda nozzle neck, the recirculation flow ratios at the forward position and the neck position were nearly almost the same value, 1.843, and 1.696 at the expansion position, their mean temperatures were $559.8^{\circ}C$ and $544.3^{\circ}C$, respectively.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.389-396
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• 2012

Objective: The aim of this study is to design an auto showering system regarding bed type for old people or bedridden patients. Background: The rapid growth concerning the aging population leads to an increase in elderly bedridden patients living in senior care centers and hospitals where care givers have difficulty bathing older people with limited mobility. Method: In this study, a showering equipment for experiment was based on anthropometric and researching existing products. The nozzle position was optimized by showering tests and simulations using showering equipment. Results: The problems regarding the existing products were analyzed and the nozzle position was optimized through showering tests. The number, position, and spraying angle of the nozzle were optimized through showering simulations. The automatic showering system concerning bed type was designed by considering their results. Conclusion: When designing an automatic showering system, the most important design element involves determining the position of nozzle and angle of water injection and the number of nozzles. The system was developed by applying the results through user centered-research. Application: The user centered-research for developing products was applied directly in order to develop automatic baths, showering products etc. Furthermore, it was also available to be applied towards senior friendly products.

• Resources Recycling
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• v.11 no.3
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• pp.17-24
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• 2002

There has been an increasing demand over the years for steels with lower[s] content. For the purpose of improving the efficiency of desulphrization in the powder injection process of ladle, experimental studies were carried out by using cold model to optimize the lance configuration, gas flow rate, immersion depth of lance nozzle, position of lance nozzle relative to the ladle and the effect with slag, etc. As the results of this study, it was made clear that 2-hole nozzle lance (C, E type) placed in an asymmetric position gives the shortest mixing times.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.41-48
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• 2014

Direct writing(DW) is a method of patterning materials to a substrate directly, without a mask. It can use a variety of materials and be applied to various fields. Among DW systems, the flow-based type, using a syringe pump and nozzle, is simpler than other types. Furthermore, the range of materials is exceptionally wide. In additive processes, a three dimensional structure is made of stacking layer. Each layer is made of several lines. In this regard, good surface roughness of fabricated layers is essential to three dimensional fabrication. The surface roughness of any fabricated layer tends to change with the dispensing pattern. When multiple layers fabricated by a nozzle dispensing system are stacked, control of the nozzle position from the substrate is important in order to avoid interference between the nozzle and the fabricated layer. In this study, a fluid direct writing system for three dimensional structure fabrication was developed. Experimentsto control the position of the nozzle from substrate were conducted in order to examine the characteristics of the material used in this system.