• 대한기계학회논문집B
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• 제23권1호
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• pp.69-81
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• 1999

In this research computational methods for the droplet atomization and spray wall impingement are studied for the non-evaporating diesel fuel spray. The TAB(Taylor Analogy Breakup) model and Wave model are compared with experiments in order to describe droplet atomization process. The Watkins model and O'Rourke model are compared to simulate the spray wall impingement. As a result, It is found that the application of the Wave model has a good agreement with the experimental data in the case of high pressure injection. With regard to wall Impingement phenomena, it is found that the Watkins model is appropriate to the high temperature cylinder wall condition, while the O'Rourke model is appropriate to cold starting problem.

• Journal of Mechanical Science and Technology
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• 제15권3호
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• pp.374-383
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• 2001

The spray/wall interaction is considered as an important phenomenon influencing air-fuel mixing in the internal combustion engines. In order to adequately represent the spray/wall interaction process, impingement regimes and post-impingement behavior have been modeled using experimental data and conservation constraints. The modeled regimes were stick, rebound, spread and splash. The tangential velocities of splashing droplets were obtained using a theoretical relationship. The continuous phase was modeled using the Eulerian conservation equations, and the dispersed phase was calculated using a discrete droplet model. The numerical simulations were compared to experimental results for spray impingement normal to the wall. The predictions for the secondary droplet velocities and droplet sizes were in good agreement with the experimental data.

• 대한임상전기생리학회지
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• 제2권1호
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• pp.93-100
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• 2004

Shoulder impingement syndrome is cause by the collision of acromion, acrominoclaviclar joint, coracoacromino ligament, coracoid process and synovial sac, biceps brachiialis tendon, rotator cuff muscle. Treatment for Shoulder impingement syndrome is genetally classified into two different methods; preservative method and operational method. Operational method includes rotator cuff sutura, anterior acromioplasty, arthroscope decompression. Preservative method includes rest, medicinal therapy, physical therapy. Physical therapy concentrates on pain control, functional recovery and prevention of disease progress. It is also important for physical therapy to maintain the strength of rotator cuff. Strengthening rotator cuff decreases the collision and helps the stability of shoulder joint. In conclusion, it must be aware that shoulder impingement syndrome and some other shoulder problem demand different treatment, which results in a better outcome.

• Clinics in Shoulder and Elbow
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• 제20권3호
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• pp.167-171
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• 2017

Here, a case of a 59-year-old man with rotator cuff tear and impingement syndrome caused by an ossified coracoacromial ligament is presented. Ossification of the coracoacromial ligaments can occur because of degenerative changes due to trauma or repeated stress, which can lead to impingement syndrome. Therefore, when coracoacromial ligament ossification is present, rotator cuff damage due to impingement syndrome should be considered. Here, we conducted arthroscopic subacromial decompression, removal of the ossified coracoacromial ligament, and supraspinatus and subscapularis tendon repairs. We achieved satisfactory surgical outcomes without relapse; therefore, we report this case with a literature review.

• 한국가시화정보학회지
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• 제17권1호
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• pp.26-33
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• 2019

The rapid increase in the usage of energy in the fast-changing industries has led to resource depletion and environmental conflicts. Many types of research are available on heat exchangers that undergo simple energy conversion processes. The impingement rods discussed in this study improves the durability of the heat exchanger and ensure the stability of the operation. However, it is uncertain about selecting the installation location of the impingement rods. The commercially available CFD code, ANSYS CFX, is used for the impingement rods installation.

• 한국가시화정보학회지
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• 제20권2호
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• pp.28-37
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• 2022

Flow characteristics of jet impingement over concave hemispherical surface with effusion cooling holes is relatively more complex than that of a flat surface, so the experimental validation for computational fluid dynamics (CFD) results is important. In this study, experimental results were compared with simulation results obtained by assuming different turbulence models. The vortex was observed in the region between the central jets where the recirculation structure appeared. The different patterns of vorticity distributions were observed for each turbulence models due to different interaction of the injected jet flow. Among them, the transition k-kl-ω model predicted similarly not only the jet potential core region with higher velocity, but also the recirculation region between the central jets. From the validation, it may be helpful to accurately predict heat and mass transfer in jet impingement/effusion hole system.

• 대한물리치료과학회지
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• 제3권4호
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• pp.121-138
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• 1996

견관절 충돌증후군의 원인은 다양하다. 대결절과 견봉과 같은 뼈의 변성으로 견봉 밑의 공간이 좁아진 경우나 회전근개가 약해지거나 관절주머니가 딱딱해지거나(capsular tightness) 상완관절의 불안정성으로 인해서 상완골두가 비정상적으로 이동하여 견봉밑의 공간이 좁아진 경우에 충돌증후군이 걸리게 된다. 충돌증후군에 걸린 어깨를 잘 치료하기 위해서는 견관절의 생체역학 해부학과 병의 원인을 잘 알아야 한다. 충돌증후군의 치료는 상완관절과 견흉관절의 운동을 회복시키고 회전근개와 견갑근육의 기능을 회복시키는데 초점을 맞춰야 한다. 또한 동적인 안정성(dynamic stabilization)을 향상시키는 운동들도 포함시켜서 치료한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.489-496
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• 2001

Two perforated plates are used to investigate local heat/mass transfer characteristics in an impingement/effusion cooling system. A naphthalene sublimation method is conducted to determine the local heat/mass transfer coefficients on the upward facing surface of the effusion plate. The two plates are placed in parallel position with gap distances of 1, 2, 4 and 6 times of effusion hole diameter. The effects of hole arrangements of the plates are studied for staggered, square, and hexagonal arrays. The experiments are conducted at Reynolds number of 10,000 based on the effusion hole diameter. The results show that the smaller hole size in the staggered array has the higher transfer coefficients on the stagnation region due to the formation of higher momentum flows through the impingement holes. In the square array, heat/mass transfer on the target plate is more uniform as the number of impingement holes increases. High and uniform heat/mass transfer coefficients are obtained in the hexagonal array.

• 대한관절경학회지
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• 제12권3호
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• pp.217-221
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• 2008

오구 충돌 증후군은 상완골 전상방 면과 오구견봉 궁 후외측면의 비정상적 접촉에 의해 발생하며, 그 원인으로는 외상성, 특발성 및 의인성 인자가 있다. 그 중 외상에 의한 경우는 견갑골 경부, 오구 돌기, 또는 상완골 소결절 골절이 원인이 될 수 있다. 상완골 소결절 부정 유합에 의한 오구 충돌 증후군은 드문 질환으로 치료에 대해서는 주로 개방적 수술이 사용되어 왔으나 관절경적 오구 돌기 성형술과 함께 소결절의 경피적 고정술을 보고한 예는 없었다. 이에 저자들은 상완골 소결절 부정 유합으로 발생한 오구 충돌 증후군에 대하여 관절경적 수술로 치유된 1 예를 경험하였기에 문헌 고찰과 함께 보고하고자 한다.

• 한국분무공학회지
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• 제9권1호
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• pp.37-42
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• 2004

In a port fuel injection system of engine, a large part of fuel injected into an intake port adheres on its wall and inlet valve. Consequently, the wall impinging spray interaction might occur the generation of several harmful phenomena. There are uncontrollable mixture formation, an accidental backfire and unburned hydrocarbons. Therefore, it is important to analyze the fuel behavior during the spray-wall interaction. In this study, splash characteristics of impingement and reflecting or scattering behavior of droplets of fuel injected from EFI nozzle were studied experimentally. A test fuel used is LAWS and its physical characteristics are similar to the conventional gasoline except for the ignition point. Since the liquid film formed immediately after impinging on an impingement plate is unstable, it is easy to cause secondary disintegration. In addition, when the intermittently impingement on the impingement plate with LAWS, the splash ratio is around 0.6. If an injection period becomes longer, liquid film will become thick and the splash ratio will fall bout 10 percent. On the other hand, when the injection period of an intermittent spray is long, the same time lapse as a continuous spray is shown.