• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.177-185
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values. The three models having different shapes have one exhaust port and the model which has the vent at the closest position to where pollutes are generated is discovered to be the most efficient model. Compare to the initial model (having no separation plate), it was $1.4-1.9\%$ more efficient at temperature distribution and $9.4-11.9\%$ more at $CO_2$ concentration distribution.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.291-294
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• 2006

Exhaust system of steam turbines consists of an annular diffuser and a collector and connects the last stage turbine and the condenser. The system is used to transfer the turbine leaving kinetic energy to potential energy while guiding the flow from turbine exit plane to the downstream condenser. In the steam turbine exhaust system, distorted pressure profile is arisen by the nonaxisymmetric collector structure at the diffuser outlet, and this distorted pressure is propagated to the last stage LP turbine exit plane through the diffuser, then the last stage LP turbine experiences asymmetric back pressure. It is known that the pressure recovery performance of diffuser is strongly influenced by diffuser inflow condition. In this study, the effect of exhaust system due to the changing of inlet flow condition is observed by using CFD, and the interaction of last stage LP turbine and exhaust system is investigated by using actuator disk model as modeling of turbine blade row of exhaust hood inlet.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.242-247
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• 2016

This work investigates the performances of active hood lift system(AHLS) activated by two different operating methods through the experimental test. In the AHLS, the deployment time of the system and decrement of pedestrian injury are the most important factors for the pedestrian safety during the pedestrian-vehicle impact. After introducing the working principle of AHLS using spring actuator and gunpowder actuator, the deployment time of AHLS and decrement of pedestrian injury are evaluated by the experimental test. It has been identified that the gunpowder actuator can provide a faster deploying time of AHLS.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.572-577
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• 2004

This paper presents numerical study on the performance improvement of the sirocco fan in a range hood. The performance of sirocco fan means a higher flowrate, a higher static pressure and a lower required motor power in a fixed geometry constraint. Various impeller geometric parameters, such as blade profile, blade diameter, blade thickness profile and blade exit angle, were investigated by numerically and the results were compared with each other to know the effects on the performance. In this approach, the volute geometry were fixed with the original shape. The numerical results show that the blade profile with airfoil shape and small exit blade thickness increases the performance. The blade exit angle shows optimum angle within a varied range. The efficiency of the optimized exit angle was about $10\%$ higher than the base blade exit angle and the static pressure was about $28\%$ higher at the flow coefficient 0.22.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.72-79
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• 2008

This study is to investigate the air flow around a sirocco fan which is used in a range hood. The main object of the study is to improve the flow rate of the fan by analysis of unsteady 3-dimensional incompressible flow. Overall analysis is carried out using CFD method. For this, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. First, verification of the CFD results is done by comparing the experimental data with the numerical data for the suction flow rate. It is confirmed that two results are well consistent. Then for the improvent of flow rate, the effect of shape factors such as diameter ratio of fan, geometry of case, cut-off aperture and guide angle of case exit on the suction flow rate was considered. Especially, for a new design of housing, the principle of Archimedes spiral was used. The overall analysis was applied to a new design of housing, and the result showed an increase of flow rate by 10.7%.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.265-269
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• 2016

In this research, the performances of active hood lift system(AHLS) are investigated according to the structural improvement through the experimental test. After introducing the working principle of the AHLS activated by a gunpowder actuator, the structural problems that cause the inefficiencies in the actuation are analyzed to reduce the deployment time of system. Sequentially, the improved structural model is proposed base on the analysis. The deployment time of AHLS are evaluated by the experimental test, and it has been identified that the improved model can provide a faster deploying time of AHLS.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.483-488
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• 2009

When a train enters into the tunnel with high speed, a compression wave generated inside the tunnel has been studied as a one-dimensional phenomenon. However, one-dimensional approach can't analyze 3-dimensional flow effect in the vicinity of the train body. In this research, so as to overcome this weak point, a prediction method of the wavefront of a compression wave using steady state solution has been used for the parametric study considering 3-dimensional effects of the interactions between trains and tunnels. The effective hood shapes were deduced in both cases of the train's entry into the tunnel on the single track and on a side of the double track. As a result, in case of the train's entry on a side of the double track, the increase of compression wave value propagated to the tunnel inside have appeared compared with the train's entry on the single track. Also, a horizontally convex elliptic hood shape is more effective at the train's entry on a side of the double track for the purpose of a decrease of wavefront gradient of a compression wave.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.468-476
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• 2019

This paper presents the means of improving the strength of LTV's FRP structure for resolve and prevent quality problems. LTV secures enough kerb weight by applying FRP materials at hood and rear van assembly. However, because of FRP's inherent limitations, many initial quality problems such as crack at connections have occurred. Moreover, hood assy' is concerned about fall of endurance, because hood assy' have operated in abnormal condition. Therefore, this study executes lamination structure optimizations of FRP structure for improving bending strength. As a results, hood and rear van's bending strength at connections is improved 8.1 times and 1.5 times, respectively. Also hood assy's plate secures endurance life and improve 1.7 times of critical load about abnormal operating conditions through 1.4 times improvement of bending strength.

• Phonetics and Speech Sciences
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• v.1 no.4
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• pp.39-46
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• 2009

This study compares the perception of English high tense and lax vowels (/i, I, u, $\mho$/) by English speakers and Korean speakers of English. The four vowels were produced in /hVd/ context by a native speaker of English, and each word's vowel duration was manipulated to range from 170ms to 290ms in 30ms increments. Two English speakers and six Korean speakers of English were asked to listen to pairs of tense and lax vowel words with manipulated vowel durations and to identify the pair by choosing either heed-hid or hid-heed for front vowels and either who'd-hood or hood-who'd for back vowels. The results show that English speakers distinguished tense vowels from lax vowels with 100% accuracy regardless of the different durations, compared to 62% accuracy for Korean speakers of English. Most errors occurred for lengthened lax vowels and shortened tense vowels. The results of this study demonstrate that Korean speakers mainly rely on vowel duration as a cue to discriminate the tense and lax vowels. The theoretical and pedagogical implications of this finding are discussed.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.372-378
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• 2005

To enhance educational effect for exhaust ventilation system, more instructive educational engineering such as experimental system should be needed. This study was performed to 1) manufacture the basic experimental system for local exhaust ventilation, 2) experiment with this system and 3) develop methodology of exhaust ventilation education. With this system, three pressures (static pressure(SP), velocity pressure(VP) and total pressure(TP)) were measured and illustrated and the graphic shapes agreed to theoretical ones relatively. Entry loss factor ($F_h$) of each hood was found to be different with hood shape, duct velocity and flow rate. This result implies that precise $F_h$ should be determined case by case and a industrial hygienist should not be dependent on the existing values. Pressure loss using velocity pressure method and characteristics of air movement near hoods using fume were grasped with this system. But larger system should be recommended to produce more precise experimental results.