Full Cone Type 스월노즐에서 단일분무와 이중분무의 중첩영역에 대한 충격력 평가

김태현 ( T. H. Kim ),성연모 ( Y. M. Sung ),정흥철 ( H. C. Jeong ),김덕줄 ( D. J. Kim ),최경민 ( G. M. Choi ) 한국분무공학회 2011 한국액체미립화학회지 Vol.16 No.1

The impact force on the single and overlap region of twin spray was experimentally evaluated using visualization method in full cone type swirl nozzle spray. Visualization of spray was conducted to obtain the spray angle and breakup process. The photography/imaging technique, based on Particle Image Velocimetry (PIV) using high-speed camera, was adopted for the direct observation of droplet motion and axial velocity measurement, respectively. Droplet size was measured by Particle Motion Analyze System (PMAS). The purpose of this study is to provide fundamental information of spray characteristics, such as impact force, for higher etching factor in the practical wet etching system. It was found that the spray angle, axial velocity and impact force were increased with increasing the nozzle pressure while droplet size decreased with increasing the nozzle pressure. Droplet size increased as the distance from nozzle tip was decreased. The impact force of twin spray in the overlap region was about 63.29, 67.02, 52.41% higher than that of single spray at 40, 50 and 60 mm of nozzle pitch, respectively. Also, the nozzle pitch was one of the important factors in the twin spray characteristics.

The Effect of Spray Characteristics on the Etching of Invar Alloy with FeCl3 Solution

정흥철,김동욱,최경민,김덕줄 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.4

The objective of this study was to investigate the significant characteristics in the sprays of industrial etching nozzles for the sake of process design. The experiment was carried out with different spray pressures and industrial nozzles in the spray etching. Characteristics of the spray, such as the axial velocity and the Sauter mean diameter (SMD), were obtained through the Phase-Doppler Anemometer (PDA). The impact force was calculated through the spray characteristics. It was found that liquid with higher spray pressure resulted in a smaller SMD, higher droplet velocity, and greater impact force. The depth of etching was increased in the case of higher spray pressure. When the spray angle oscillated between 20° and -20°, the effect of etching remained constant. The relationships between the spray characteristics and the etching characteristics were analyzed. The depth of etching had significant, positive correlations with the axial velocity and the impact force. Four liquids of different kinematic viscosities were used to reveal the effects of the kinematic viscosity on the spray characteristics. The results indicated that a lower viscosity of the spray yielded a higher etching rate than a higher viscosity of the liquid. The results clearly show that the characteristics of the spray etching are strongly related to the spray characteristics with the spray conditions.

산업용 에칭노즐을 이용한 Invar합금판의 식각에 분사각과 압력이 미치는 영향

정흥철(Heung-Cheol Jeong),김동욱(Dong-Wook Kim),최경민(Gyung-Min Choi),김덕줄(Duck-Jool Kim) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.8

The purpose of this study was to investigate the significant characteristics in spray of industrial etch-nozzle for the design of process. The experiment was carried out with different spray pressure and industrial nozzle in wet etch. The characteristics of liquid spray, such as axial velocity and sauter mean diameter measurements were obtained by PDA. And impact force was calculated from spray characteristics. It was found that the fluid with higher spray pressure resulted in the smaller SMD and the higher droplet velocity and impact force. The depth of etch was increased in case of high spray pressure. In the case of injection angle oscillated between 20°, the result indicated constant effect of etch. The correlation between the spray characteristics and etch ones were analyzed. The depth of etch had good positive correlation with axial velocity and impact force. The result clearly shows that the characteristics in wet etch are strongly related to the spray characteristics with process.

Experimental Study on Spray Etching Process In Micro Fabrication of Lead Frame

Jung, Ji-Won,Choi, Gyung-Min,Kim, Duck-Jool The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.12

The objective of this study is to obtain detailed information for the micro fabrication of lead frames by applying spray technology to wet etching process. Wet etching experiments were performed with different etching parameters such as injection pressure, distance from nozzle tip to etched substrate, nozzle pitch and etchant temperature. The characteristics of single and twin spray were measured to investigate the correlation between the spray characteristics and the etching characteristics. Drop size and velocity were measured by Phase-Doppler Anemometer (PDA). Four liquids of different viscosity were used to reveal the effects of viscosity on the spray characteristics. The results indicated that the shorter the distance from nozzle tip and the nozzle pitch, the larger etching factor became. The average etching factor had good positive correlation with average axial velocity and impact force. It was found that the etching characteristics depended strongly on the spray characteristics.

중량충격원에 따른 콘크리트 바닥판의 차음특성 분석 및 평가에 관한 연구

유승엽(Yoo, Seung-Yup),연준오(Yeon, Jun-Oh),전진용(Jeon, Jin-Yong) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.10

In this study, the impact force levels of bang machine and impact ball were measured, then the heavy-weight impact sounds generated by the bang machine and impact ball were investigated. It was found that the heavy-weight impact sources generated through modal excitation, and the impact force of the impact ball was similar to that of real impact source. The heavy-weight impact sounds were also measured in the real apartments with different slab thickness and floor structures. The results showed that the floor impact sound levels in terms of $L_{iFmax,AW}$, generated by impact ball sounds were reduced by using the resilient isolators. The frequency characteristics of heavy-weight impact sounds at 125 and 250 Hz were consistent with the characteristics of impact force spectrum. However, the difference between the impact sounds and the impact forces were found at 63 and 500 Hz due to the resonance of the floor structure and flanking noise, respectively.

Experimental and numerical study on the oblique water-entry impact of a cavitating vehicle with a disk cavitator

Chen, Cheng,Yuan, Xulong,Liu, Xiyan,Dang, Jianjun The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

In this paper, the oblique water-entry impact of a vehicle with a disk cavitator is studied experimentally and numerically. The effectiveness and accuracy of the numerical simulation are verified quantitatively by the experiments in this paper and the data available in the literature. Then, the numerical model is used to simulate the hydrodynamic characteristics and flow patterns of the vehicle under different entry conditions, and the axial force is found to be an important parameter. The influences of entry angle, entry speed and cavitator area on the axial force are studied. The variation law of the force coefficient and the dimensionless penetration distance at the peak of the axial force are revealed. The research conclusions are beneficial to engineering calculations on the impact force of a vehicle with a disk cavitator over a wide range of water-entry parameters.

Experimental and numerical study on the oblique water-entry impact of a cavitating vehicle with a disk cavitator

Cheng Chen,Xulong Yuan,Xiyan Liu,Jianjun Dang 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

In this paper, the oblique water-entry impact of a vehicle with a disk cavitator is studied experimentally and numerically. The effectiveness and accuracy of the numerical simulation are verified quantitatively by the experiments in this paper and the data available in the literature. Then, the numerical model is used to simulate the hydrodynamic characteristics and flow patterns of the vehicle under different entry conditions, and the axial force is found to be an important parameter. The influences of entry angle, entry speed and cavitator area on the axial force are studied. The variation law of the force coefficient and the dimensionless penetration distance at the peak of the axial force are revealed. The research conclusions are beneficial to engineering calculations on the impact force of a vehicle with a disk cavitator over a wide range of water-entry parameters.

Dynamic Characteristics for Traditional Wooden Structure in Korea by using Impact Hammer Test

Park, Sung-Ah,Choi, Jae-Sung,Min, Kyung-Won 단국대 부설 리모델링연구소 2010 리모델링 연구소 논문집 Vol.8 No.2

This paper presents an investigation on dynamic characteristics of Heunginjimun through both ambient vibration and impact hammer tests. Heunginjimun, treasure No. 1 in Seoul, Korea, is a traditional wooden structure. Ambient vibration test is performed and spectrum analysis of time history is carried out to identify dominant frequency contents of Heunginjimun. Impact hammer test is undertaken to find the natural frequency of Heunginjimun with frequency response functions and phase information. Test results show that natural frequencies are 1.lHz, l.5Hz, 3.2Hz and 4.2Hz in two principal axes. Natural frequencies obtained by the tests are used to find the lateral stiffness of Heunginjimun. Simple dynamic models for Heunginjimun are suggested based on the moment resistance from joint beams and the restoring force due to column rocking. Lateral stiffness is found with identified natural frequencies and simple dynamic models.

Analysis on the Dynamic Characteristics of Cross-Tunnel Structures under Wheel-Rail Impact Forces

Zhigang Wang,Lianjin Tao,Jie Dong 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.9

The dynamic behaviour of cross-tunnel structures under the wheel-rail impact forces of heavyhaultrains is complicated. This paper establishes an impact force excitation input model tosimulate the wheel-rail vertical forces of rail welded joints. The calculated results of thecorrection formula of wheel-rail vertical forces for seamless rail joints are in good agreementwith the measured data and meet the accuracy requirements. The present paper describes a1/50 scale model experiment based on the case of the newly-built Jing-Zhang Railwayunderneath the existing Tang-Hu Heavy Haul Railway. Numerical simulation analysis usesFLAC3D to simulate the experiments and investigate the dynamic soil pressure characteristicsunder different factors. The test and numerical results showed that the dynamic responses ofthe upper tunnel monitoring points are stronger than the lower tunnel, but the maximumvertical settlement of the lower tunnel vault is bigger and prone to damage. As the depthincreases, the stress of the surrounding rock interlayer at each monitoring point graduallydecreases. In-depth, the surrounding rock stress decreased approximately non-linearly withincreasing surrounding rock grade and surrounding rock interlayer thickness.

소형 수로실험을 통한 토석류 유동속도 추정식 평가

유송,임상준 한국산림과학회 2017 한국산림과학회지 Vol.106 No.4

토석류는 빠른 속도와 넓은 퇴적 범위 등으로 인명 및 재산 피해를 야기하는 산지토사재해이다. 토석류 피해 저감 을 목적으로 효과적인 사방 구조물을 설계하기 위해서는 토석류의 충격력을 정확하게 산정하여야 한다. 토석류의 유동속 도는 토석류 충격력을 추정하는데 중요한 요인이다. 따라서 이 연구에서는 소형 수로실험을 통해 수로경사 및 시료 조건 에 따른 토석류의 유동특성을 실험적으로 분석하고, 토석류 유동속도 추정식의 유동저항계수를 추정하였다. 유동속도는 수로의 경사조건 및 시료의 점성조건에 유의한 변화를 보였다. 유동깊이는 수로경사에 대해서 유의한 차이를 보였으나 시 료의 점성변화에 대해서는 유의한 변화를 보이지 않았다. 유동저항계수를 계산하여 분석한 결과, Voellmy flow 모형의 Chezy 상수(C1)가 상대적으로 수로실험 결과를 잘 재현하였다. 또한, 실제 토석류 사례와의 비교 결과, 유동깊이에 관계 없이 일정한 값(20.19 m-1/2 s-1)을 보였다. 따라서, C1은 다양한 발생규모의 토석류에 대한 유동속도 추정에 잘 활용될 수 있을 것으로 보인다. With its rapid velocity and wide deposition, debris flow is a natural disaster that causes loss of human life and destruction of facility. To design effective debris barriers, impact force of debris flow should be first considered. Debris flow velocity is one of the key features to estimate the impact force of debris flow. In this study, we conducted small-scale flume experiments to analyze flow characteristics of debris flow, and determine flow resistance coefficients with different slope gradients and sediment mixtures. Flow velocity significantly varied with flume slope and mixture type. Debris flow depth decreased as slope increased, but difference in depth between sediment mixtures was not significant. Among flow resistance coefficients, Chezy coefficient (C1) showed not only relatively highest goodness of fit, but also constant value (20.19 m -1/2 s -1 ) regardless the scale of debris flow events. The overall results suggested that C1 can be most appropriately used to estimate flow velocity, the key factor of assessing impact force, in wide range of debris flow scale.