• 한국분무공학회지
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• 제4권4호
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• pp.30-37
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• 1999

The breakup characteristics of liquid sheet formed by the liquid rocket injector has a close relation with the combustion efficiency. In this paper, basic characteristics of droplet size and velocity distribution were measured with PDPA for the Like Doublet Impinging Injector. Test variables were the angle of impact, the diameter of orifice and jet velocity. Water was used as test fluid. As a result, for impingement angle less than 90 degree, following correlations were obtained between drop size and design parameters : $D_{32}({\mu}m)=295.0{\times}V^{-0.09}\times(2\theta)^{-0.1}{\times}d^{0.072}$. For impingement angle greater than 100 degree, drop sizes were increased but eventually converged to a certain limiting value.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.225-228
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• 2002

Supersonic jet impingement on a flat plate has been investigated to show the flow physics for different jet heights and to demonstrate the adequacy of the characteristics-based flux-difference Wavier-Stokes code Current study also compares the steady-state solutions obtained with variable CFL number for different grid spacing with the time-accurate unsteady solutions using the inner iterations, displaying a good agreement between the two sets of numerical solutions. The unsteady nature of wall fluctuations due to bouncing of the plate shock is also uncovered for high pressure ratios. The methodology is then applied to a complex vertical launcher system where the jet plume hits the bottom wail, deflects into the plenum and eventually exits through the vertical uptake. Flow structures within vertical launcher system are captured and solutions are partially verified against the flight test data. Present jet impingement study thus shows the usefulness of CFD in designing a complex structure and predicting flow behavior within such a system.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.86-100
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• 1998

The impingement of the fuel spray on the wall within the combustion chamber in compact high-pressure injection engines and on the intake port wall in port-fuel-inje- ction type engines is unavoidable. It is important to understand the characteristics of impinging spray because it influences on the rate of fuel evaporation and droplet distrib- ution etc. In this study, the numerical study for the characteristics of spray/wall interaction is performed to test the applicability and reliability of spray/wall impingement models. The impingement models used are stick model, reflect model, jet model and Watkins and Park's model. The head of wall-jet eminating radilly outward from the spray impingement site contains a vortex. Small droplets are deflected away from the wall by the stagnation flow field and the gas wall-jet flow. While the larger droplets with correspondingly higher momentum are impinged on the wall surface and them are moved along the wall and are rolled up by wall-jet vortex. Using the Watkins and Park's model the predicted results show the most reasonable trend. The rate of increase of spread and the height of the developing wall-spray is predicted to decrease with increased ambient pressure(gas density).

• Clinics in Shoulder and Elbow
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• 제2권1호
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• pp.35-40
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• 1999

Impingement syndrome is caused by a conflictual status between rotator cuff, subacromial bursa and anatomic and functional coracoacromial arch. The purpose of this study was to assessment the coracoacromial arch by MRI and to determine major factors among five components of coracoacromial arch. We analyzed forty-two cases of clinical impingement sign and test positive and postoperative confirmed diagnosed from March, 1991 to January, 1999. We evaluated acromial end abnormality according to the Bigliani acromial type and formation of osteophyte. Clavicular end abnormality classified flat, outward protrusion, inward protrusion to coracoacromial arch. Acromioclavicular joint abnormalities were advanced osteoarthritis and positive signal change. Coracoacromial ligament thickening was above 2 mm in oblique sagittal image. Coracoid process abnormality was inward protrusion to coracoacromial arch. All consecutive patients abnormalities were as follows: clavicular end osteophyte formation and inward protrusion to coracoacrmial arch were 30%, acromial end osteophyte formation was 28%, advanced acromioclavicular joint arthritis and osteophyte formation were 56%, coracoacromial ligament thickening was 24% and no coracoid process inward protrusion to coracoacromial arch. Impingement syndrome combined with rotator cuff tear group abnormalities were clavicular end(40%), acromial end(40%), acromioclavicular joint(20%), coracoacromialligament(20%) and coracoid process abnormality(0%) respectively. Only impingement syndrome group abnormalities were clavicular end(25%), acromial end(31%), acromioclavicular joint(62%), coracoacromial ligament(25%) and coracoid process(0%) respectively. Acromial type I(flat) were 6 cases, type II(curved) were 26 cases and type III(hooked) were 10 cases. We concluded that the most important contributing factors for impingement syndrome was acromial type and second was acromioclavicular joint arthritis and bony spur formation.

• Clinics in Shoulder and Elbow
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• 제2권1호
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• pp.28-34
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• 1999

Purpose: We studied magnetic resonance imaging of acromion morphology and superior displacement of the humeral head in the patients with diagnosis of rotator cuff impingement syndrome, and also documented the relationship of type Ⅲ acromion to the rotator cuff tear. Materials and Methods: We reviewed retrospectively 40 patients(40 shoulders) who had arthroscopic treatment for the diagnosis of stage II impingement or rotator cuff partial tear and did not have other risk lesions except acromion factor. The mean age was 48.7 years at operation. 21 men(2l shoulders), mean age of 26 years, were used as controls. Acromial type, tilt, and superior displacement of humeral head in sagittal plane, and acromial lateral angulation in coronal plane were measured. Four parameters of the patients were compared with those of control group. And then, the data were subdivided and analyzed with respect to acromial type and patient age in the impingement group. Student t test and multi-way ANOVA were used. Results: In impingement group, Farley's type I acromion, 33%, type Ⅱ, 38%, type Ⅲ, 27% and type Ⅳ, 2%. Superior displacement of humeral head( 4.8mm) were characteristic in the impingement group compared with the control group(1.3mm)(p<0.05). But acromial tilt and lateral angulation were not statistically different. In the analysis of the impingement group, the change of 4 parameters was not significant with respect to age(p>0.05), but lateral angulation in type I acromion(18 degree) and superior displacement of humeral head in type Ⅲ acromion(6.3mm) were significantly increased(p<0.05). All 4 parameters were not different between two subdivided types of type Ⅲ acromion. Conclusion: All types of acromian and large lateral angulatian cauld develop impingement syndrame, but acromial tilt was nat risk factar. Appearance of type Ⅲ acromian and increased superiar displacement of humeral head were characteristic findings in the impingement syndrame. Superiar displacement of humeral head as a result of degenerative change of rotatar cuff was probably primary cause far impingement. The type Ⅲ acromian might be an acquired farm, which cauld be expected to accelerate the tear of rotatar cuff as a cansequence.

• PNF and Movement
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• 제17권3호
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• pp.431-439
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• 2019

Purpose: This study investigated the effects of motion taping on muscle stiffness, muscle tone, and pain in middle-aged women with shoulder impingement syndrome. Methods: The participants comprised 30 middle-aged women with shoulder impingement syndrome. This study measured muscle stiffness, muscle tone, and pain. In the experimental group, the tape was attached after physical therapy; the control group only received physical therapy. In the intervention period, the treatment program was conducted three times a week for a total of four weeks, and the values before and after the intervention were compared and analyzed. For statistical processing, a correspondence test was performed before and after the intervention at a significance level of 0.05, and the comparison between the groups, before and after the intervention, was made using an independent test. Results: In the experimental group, there was a difference in muscle stiffness, muscle tone, and intensity of pain. In addition, there was a significant difference between the control group's emotional domain regarding muscular stiffness and pain and the experimental group. However, there was no significant difference in muscle tone and grade of pain, and intensity of pain for the control group. Conclusion: This study showed that, when physical therapy and motion taping were administered to middle-aged women with shoulder impingement syndrome, it had a more positive affect on the sensory and emotional parts of the muscle tone and pain compared to physical therapy alone.

• 대한정형도수물리치료학회지
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• 제28권3호
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• pp.9-19
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• 2022

Background: The study objectives were to investigate the effect of Kinesio taping, Mulligan taping on push-off-test and maximum grip strength in elite men's artistic gymnast with wrist impingement syndromes. Methods: The subjects of this study were 18 wrist impingement syndromes men's artistic gymnast and randomly assigned to a Kinesio taping group, Mulligan taping group. Weight-bearing wrist pain and Muscle strength were assessed with push-off-test (POT) and the maximum grip strength (MGS). Results: As a result of the research, there were no significant difference in POT in pre and post group in the Kinesio taping (p>.05). But Mulligan taping group were significant difference in POT (p<.05). In comparison after intervention between each other groups, there was a no significant difference on (p<.05), but no significant difference on post (p>.05). there were significant difference in MGS in both pre and post group in the Kinesio taping and Maximum Grip Strength (p<.05). In comparison after intervention between each other groups, there was a no significant difference on pre (p<.05), but no significant difference on post (p>.05). Conclusion: This results suggests that Mulligan taping are encouraged due to effects on pain, Muscle strength increase in elite men's artistic gymnast with wrist impingement syndromes.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.359-365
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• 2000

Port facilities and marine structures used in marine environment were encountered to corrosion damages because of the influence of $Cl^-$. Generally, to protect these accidents, mainly applied anti-corrosion paint and epoxy coating. But it was still remained erosion-corrosion damage such as impingement erosion, cavitation erosion, deposit attack. There was needs to develope the new coating materials to protective those corrosion damages. This paper, polyester glass flake, vinylester glass flake lining and epoxy coating for SS were investigated electrochemical tests and cavitation erosion test for corrosion behaviour under sea water. The main results obtained are as follows, 1) Surface of epoxy coating appear erosion pin hole but surface of polyester glass flake and vinylester glass flake lining do not appear erosion pin hole after impingement-cavitation erosion test in sea water. 2) Weight loss of polyester glass flake and vinylester glass flake lining do not occur after impingement-cavitation erosion test in sea water. 3) Corrosion current density of polyester glass flake lining less drained than epoxy coating and substrate under corrosion potential.. 4) Corrosion current density of vinylester glass flake lining with three coating less drained than that of polyester glass flake lining with two coating.

• Corrosion Science and Technology
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• 제12권4호
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• pp.179-184
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• 2013

Pipe wall thinning caused by erosion and corrosion can adversely affect the operation of aged nuclear power plants. Some injured workers owing to pipe rupture has been reported and power reduction caused by unexpected pipe damage has been occurred consistently. Therefore, it is important to develop erosion-corrosion damage prediction model and investigate its mechanisms. Especially, liquid droplet impingement erosion(LDIE) is regarded as the main issue of pipe wall thinning management. To investigate LDIE mechanism with corrosion environment, we developed erosion-corrosion damage simulation apparatus and its capability has been verified through the preliminary damage experiment of 6061-Al alloy. The apparatus design has been based on ASTM standard test method, G73-10, that use high-speed rotator and enable to simulate water hammering and droplet impingement. The preliminary test results showed mass loss of 3.2% in conditions of peripheral speed of 110m/s, droplet size of 1mm-diameter, and accumulated time of 3 hours. In this study, the apparatus design revealed feasibility of LDIE damage simulation and provided possibility of accelerated erosion-corrosion damage test by controlling water chemistry.

• 한국해양공학회지
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• 제17권2호
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• pp.40-46
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• 2003

The corrosion resistance of super duplex stainless steel on both its fibrous and dispersed phase was investigated. These structures consist of various volume fraction and distribution of austenite structure, which were obtained by changing the heat treatment temperature and cycle. The fibrous phase had higher austenite volume fraction than that of the dispersed phase at the same temperature. Corrosion resistance of super duplex stainless steel was evaluated through an immersion test and an impingement test, using 35% HCI and sea water, respectively. Super duplex stainless steel was compared with STS316L and STS304. The corrosion resistance of super duplex stainless steel was superior to ST316L and STS304. The dispersed phase of super duplex stainless steel was more stabilized than the fibrous phase in corrosion. The magnitude of corrosion rate was in order STS304, STS316L, fibrous phase of super duplex stainless steel and dispersed phase of super duplex stainless steel.