• Tribology and Lubricants
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• 제23권6호
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• pp.272-277
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• 2007

Various type of rotary unions are widely used to provide fluids between rotating parts. To prevent fluid leakage, most of the rotary unions adopt mechanical seals which is highly reliable but too expensive and complicate. In this paper, a simple lip seal system made of PTFE is adopted in designing of a compact rotary union. Using MARC, the behavior characteristics of lip seal are investigated for seal mounting process, and obtained variations of contact pressure distribution and contact width with interferences and fluid pressures. The results showed that contact width are increased with interference and pressure. The maximum contact pressure are also increased up to a certain interference and pressure, however, then decreased. The numerical methods and results can be applied in designing and performance improvement of lip seal adopted rotary union, and further extensive studies are required.

• 한국가스학회지
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• 제18권4호
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• pp.51-55
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• 2014

본 연구에서는 한곳에서 접촉하는 오링과 여러 곳에서 접촉하는 멀티접촉패킹에 대한 밀봉특성을 유한요소법으로 해석하였다. FEM 해석결과에 의하면, LP가스압력 1.8MPa을 공급하였을 때 기존의 오링에서는 밀봉성에 관련된 2.5MPa의 수직접촉 최대응력을 발생하였다. 반면에 새롭게 고안된 멀티접촉패킹에서는 3.01MPa이 발생하여 20.4%나 높아진 밀봉성이 향상되었음을 알 수 있다. 또한, 밀봉내구 안전성에 밀접한 관련이 있는 압출현상은 기존 오링의 경우 1.62MPa의 가스압력에서 발생되었지만, 멀티접촉패킹에서는 1.8MPa 정도로 가스내압을 올려도 압출현상이 발생되지 않는 것은 오랫동안 밀봉작용을 한다는 것을 의미한다. 따라서 밀봉성과 내구안전성을 높게 요구할 때는 한곳에서 접촉하는 기존의 오링보다는 여러 곳에서 접촉하는 멀티접촉패킹을 사용하는 것이 유리함을 알 수 있다.

• 대한음성언어의학회:학술대회논문집
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• 대한음성언어의학회 2003년도 제19회 학술대회
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• pp.147-147
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• 2003

Recent aerodynamic and acoustic studies of VPI(velopharyngeal insufficiency) are non-invasive and safety, therefore, many researchers have used it to diagnose the hyper/hyponasality and articulation disorders of cleft palate patients. The purpose of this study was to estimate mainly the oropharyngeal air pressure and over all air flow in cleft lip and palate patients. The pressure-collecting catheter was positioned in the oropharyngel cavity around tongue base. Twelve adult control group and three cleft lip & palate patients were participated to this experimentation. Aerophone II was used to measure peak air flow, mean air flow, phonatory airflow, phonatory efficiency and resistance. The results were as follows: 1) Airflow of cleft lip ＆ palate patients group were higher than those of control group. Fricative sounds /s/ and /s'/ showed the statistic significance of mean airflow and volume data. 2) Intraoral air pressure of cleft lip ＆ palate patients was lower than those of control group.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.520-525
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• 2003

Supersonic jet issuing from a nozzle invariably cause high-frequency noises. These consist of three principal components ; the turbulent mixing noise, the broadband shock-associated noise, and the screech tone. In present study, it was experimentally investigated to the effect of nozzle lip thickness on the characteristics of supersonic jet noise. The convergent-divergent nozzle of a design Mach number 2.0 was used in experiment. With three different nozzle-lip thicknesses, the jet pressure ratio was varied in the range between 2.0 and 12.0. Acoustic measurements were conducted by microphones in an anechoic room, and the major structures of the supersonic jets were visualized by a Schlieren optical system to investigate the effect of nozzle lip thickness. The measured results show that the characteristics of supersonic jet noise, such as overall sound pressure level (OASPL) and screech frequency, strongly depend upon the thickness of nozzle-lip.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2023-2028
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• 2004

The effects of nozzle-lip thickness on the relationship between screech tone and broadband shock-associated noise were experimentally investigated using a convergent-divergent nozzle with a design Mach number of 2.0. Overall sound pressure levels (OASPL) and noise spectra were obtained at far-field locations. Schlieren optical system was used to visualize the flow-fields of supersonic jets. A baffle plate was installed at the exit of the nozzle and its size was varied to obtain different nozzle-lip thicknesses. Experiment was carried out over a wide range of nozzle pressure ratios from 2.0 and 18.0, which corresponds to over- and under-expanded conditions. The results obtained clearly show that the screech tones are influenced by the nozzle-lip thickness. It is found that the screech tone and its peak amplitude are strongly dependent on whether the jet is over-expanded and under-expanded at the nozzle exit.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1576-1580
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• 2007

Typical lip seals are widely used as sealing mechanism of rotary and reciprocating shaft. Double lip seal has comparatively high stiffness and dynamic radial eccentricity. Usually material of these seals is made of elastomer and nonlinear finite element analysis is required to analyze behaviour of this material because Young's modulus is varied with working load. In this paper, MSC MARC/MENTAT is used for nonlinear analysis of double lip seal with pressure variation and interference. The contact normal force of double lip seal between lip and shaft is analyzed to reduce power loss when shaft rotates.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.195-200
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• 2010

Numerical investigation was conducted to study the effects of after-body configurations and nozzle lip on the PIFS(Plume Induced Flow Separation) and eat flux to the base face. Two dimensional and axi-symmetric non-equilibrium Navier-Stoke's solver with $k-{\omega}$ SST turbulence model was used to solve the launching vehicle type configuration with propulsive jet. The experimental result of Robert J. McGhee was compared with our computational results for code validation. Three types of the after-body configurations (Straight, Boat-tail, Flare type) were simulated for this study. And the nozzle lip effect was studies using the three types of base configurations same simulation conditions. As a result of numerical investigations, higher pressure ratio condition and boat-tail after-body configuration caused severe PIFS phenomenon but the flare type after-body configuration and low pressure ratio suppressed PIFS. Flare type after-body configuration and low pressure ratio case reduced heat flux to base face. The nozzle lip dispersed the heat flux widely along the base face and the nozzle lip.

• 대한구순구개열학회:학술대회논문집
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• 대한구순구개열학회 1997년도 종합학술대회
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• pp.51-51
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• 1997

• 한국정밀공학회지
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• 제26권11호
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• pp.85-91
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• 2009

A lip seal is widely used not only to prevent leakage of fluids from an actuator or a rotating shaft but also to exclude outside substances. Recently, TPU(Thermoplastic Polyurethane), which is one of the sealing materials, has been frequently used due to its excellent mechanical properties and wear resistance. The material constants for finite element analysis through the experiment on stress relaxation are presented. The reaction forces of a shaft as well as the contact pressures of a lip seal under condition before and after stress relaxation using finite element analysis were obtained, The results show that stress relaxation has not a little effect on the performance of a lip seal.

• 대한소아치과학회지
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• 제50권1호
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• pp.13-23
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• 2023

이 연구의 목적은 평균 혀, 입술, 볼의 압력을 비교하여 구강 내 근육 불균형을 확인하고 근 기능 훈련에 따른 변화를 관찰하는 것이다. 구강 악습관으로 인한 근 기능 이상이 관찰되는 환자들을 대상으로 장치를 동반한 근 기능 훈련을 시행하였다. 압력 측정 장치를 사용하여 구강 근육의 기능 향상 정도를 측정하였다. 연구 대상은 만성 구호흡, 손가락 빨기, 입술 빨기, 혀 내밀기, 잘못된 연하 습관과 같은 구강 악습관이 있는 21명의 환자들로 구성하였다. 치료 전, 두 그룹 간의 측정값을 비교했을 때 혀와 입술의 측정값 사이에 큰 차이가 관찰되었다. 혀의 측정값은 근 기능 훈련을 시작하고 나서 1개월 이후 가장 크게 증가하였고 입술의 측정값은 치료 시작 후 3개월에서 6개월 사이에 가장 큰 폭으로 증가하였다. 대조군에서 측정한 혀, 입술, 우측 볼, 좌측 볼의 값은 실험군이 근 기능 훈련을 시작하고 나서 6개월 이후 측정한 값과 매우 유사했다. 장치를 동반한 근 기능 훈련을 꾸준히 시행할 경우, 혀와 입술의 압력이 눈에 띄게 증가하는 것을 확인할 수 있다. 또한 구강 악습관으로 인한 구강 근육 불균형이 관찰되는 환자의 경우 적어도 6개월 이상의 근 기능 훈련이 추천된다.