• Title, Summary, Keyword: OLEO

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Dynamic Load Analysis of Aircraft Landing Gear (항공기 착륙장치 동하중 해석)

  • Shin, Jeong-Woo;Kim, Tae-Uk;Hwang, In-Hee
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.1
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    • pp.1-6
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    • 2008
  • Role of landing gear is to absorb energy which is generated by aircraft ground maneuvering and landing. Generally, in order to absorb the impact energy, oleo-pneumatic type shock absorber is used in aircraft landing gear. Oleo-pneumatic type shock absorber has a good energy absorption efficiency and is light in weight because structure of oleo-pneumatic type shock strut is relatively simple. In this study, dynamic load analysis for swinging arm type landing gear was performed to predict landing loads. Modeling of landing gear was conducted with MSC.ADAMS, and dynamic landing loads were analyzed based on ADS-29. Optimum landing loads were generated through adjustment of damping orifice and the analysis results were presented with various aircraft attitude.

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Response analysis of 6DOF fuselage model during taxiing for comparison of characteristics of single/double stage oleo-pneumatic shock absorber at nose (단-복동형 유.공압 완충장치의 전방장착특성 비교를 위한 6자유도 기체 모형의 지상 이동 응답해석)

  • Lee, Kook-Hee;Lee, Yoon-Kyu;Kim, Kwang-Joon;Lee, Sang-Wook
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.734-735
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    • 2008
  • Shock absorber for rotorcraft landing gear should absorb landing impact during landing and isolate vibration to fuselage during taxiing. Double stage oleo-pneumatic shock absorber is known to have better performances than single stage oleo-pneumatic shock absorber. This paper deals with the z-direction translational acceleration at mass center, roil and pitch angular acceleration of fuselage for single and double stage oleo-pneumatic shock absorber at nose landing gear when a 6DOF rigid model is taxiing on the pound.

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The Topical Absorption of Ketoprofen from Gels and Plaster in Human Volunteers (케토프로펜 겔제와 플라스터제의 피부 흡수 비교)

  • Gang, Won-Gu;Lee, Chang-Hyeon;U, Jong-Su;Gwon, Gwang-Il
    • YAKHAK HOEJI
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    • v.42 no.1
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    • pp.25-30
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    • 1998
  • This study was designed to compare the absorption fraction and extent of ketoprofen gels and a matrix typed ketoprofen plaster patch. 3g (90mg as ketoprofen) of the two gels whi ch has oleohydrogel or hydrogel as a base, respectively, and 3 pieces of plaster patches (90mg as ketoprofen) were, applied in the area of 210$cm^2$ on forearm in 12 volunteers by cross over design. Blood samples were collected serially up to 24 hours and the plasma concentrations of ketoprofen were analyzed by HPLC using flurbiprofen as an internal standard. The detection limit of the assay was 1ng/ml of ketoprofen in plasma. The pharmacokinetic parameters (e.g. $AUC_{24hr}$, $AUMC_{24hr}$, MRT, Fraction Absorbed) were calculated from the plasma concentrations time data of each volunteer. The oleo-hydrogel showed significantly higher absorption fraction and extent of ketoprofen than the current hydrogel. The mean plasma concentrations of the oleo-hydrogel were increased to 98.46${\pm}$23.15ng/ml by 6 hour after application, and increased futher to 100.61${\pm}$18.65ng/ml at 24 hour. On the other hand, those of the hydrogel were increased 17.61${\pm}$18.65ng/ml at 5 hour to 34.68${\pm}$9.65ng/ml at 24 hour gradually. Therefore the plasma concentrations of oleo-hydrogel at each measured time were 3~7 times greater than those of the hydrogel with statistical significance. The $AUC_{24hr}$ (1797.26${\pm}$52.09ng.h/ml) of the oleo-hydrogel was 3.5 times greater (P<0.05) than that (516.17${\pm}$104.52ng.h/ml) of the hydrogel. The plaster patches showed higher bioavailability ($AUC_{24hr}$ 2877.37${\pm}$578.27ng.h/ml) than the olea-hydrogel ($AUC_{24hr}$ 1797.26${\pm}$52.09ng.h/ml) without statistical significance. But the absorption fraction of the oleo-hydrogel was rather higher than that of the plaster patches during the first 6 hours after administration. These results suggest that newly developed ketoprofen gel which is used oleo-hydrogel as a base would show excellent skin permeation on topical application for the corresponding clinical indications and could be absorbed as well as plaster patches.

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Impact of Service Recovery, Customer Satisfaction, and Corporate Image on Customer Loyalty

  • ZAID, Sudirman;PALILATI, Alida;MADJID, Rahmat;BUA, Hasanuddin
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.1
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    • pp.961-970
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    • 2021
  • This study aims to examine the impact of service recovery in building customer loyalty through the mediating role of customer satisfaction and corporate image. This study also aims to examine the reciprocal relationship between customer satisfaction and corporate image in building customer loyalty. This study uses data from 126 consumers who have received recovery for a service failure in five logistics companies which operates in Southeast Sulawesi in Indonesia, namely; JNEs; J&T Express; Pandu Logistics; MEC; and TiKi. Data was collected using a questionnaire which was then distributed to all respondents via google form. The distribution of respondents at each logistics company provider was as follows: 19 respondents were customers of JNEs; 17 respondents were customers of J&T Express; 32 respondents were customers of Pandu Logistics; 21 respondents were customers of MEC; and 37 respondents were customers of TiKi's. The structural model developed in this study was tested using Partial Least Squared (PLS) method. The research found that service recovery has a direct effect on customer satisfaction and corporate image as positive and significant. Customer satisfaction and corporate image have a reciprocal relationship which then roles in building customer loyalty. Service recovery has an indirect effect on customer loyalty through the mediating role of customer satisfaction and corporate image.

Effects of Cavitation and Drop Characteristics on Oleo-Pneumatic Type Landing Gear Systems (공동현상을 고려한 유공압 방식 착륙장치의 낙하특성에 관한 연구)

  • Han, Jae-Do;Lee, Young-Sin;Kang, Yeon-Sik;Ahn, Oh-Sung;Kong, Jeong-Pyo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.2
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    • pp.193-200
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    • 2009
  • This paper investigated the drop characteristics of oleo pneumatic type landing gear for small aircraft and the effects of cavitations in modeling the landing gear system. The landing gear system employed a simple oleo pneumatic type damper without a metering pin. In general, oleo-pneumatic type landing gears are light-weighted because of it's simplicity, yet they offer excellent impact absorption characteristics. In this study, the landing gear system was modeled using MSC ADAMS, which offers a drop simulation module. After modeling the system, a series of testing was conducted, using a prototype landing gear system, to validate the analysis model and simulation results. The effect of cavitation was considered in the simulation model to obtain a better correlation between the test and simulation results. The results show that adding the cavitation effect in the simulation model significantly improved the simulation model and better captured the dynamic behaviors of the landing system. Using the 'cavitation' model, dynamics characteristics of the landing gear were further evaluated for other landing conditions, such as landing in various angles of slopes.

Comparative Study on the Several Types of Double-Acting Oleo-Pneumatic Shock Absorbers of Aircraft Part I. Mathematical Modeling (항공기 올레오식 2중 완충기 종류에 따른 특성 비교 연구 Part I. 수학적 모델링)

  • Lee, Cheol Soon;Jeong, Seon Ho;Kim, Kyung Jong;Kim, Jeong Ho;Cho, Jin Yeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.11
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    • pp.939-950
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    • 2017
  • In this work, mathematical models are newly presented for three types of double-acting oleo-pneumatic shock absorbers as the first part of a comparative study on the several types of double-acting oleo-pneumatic shock absorbers. After a typical single-acting shock absorber model is presented for the sake of completeness, mathematical models of three types of double-acting shock absorbers are proposed. To derive the models, Bernoulli equation and orifice discharge coefficient are utilized along with the assumptions of incompressibility and poly-tropic process. The proposed models are expected to be used for investigation of the salient features of several types of double-acting oleo-pneumatic shock absorbers.

Drop Test for the UAV Landing Gear Performance Verification (무인정찰기 착륙장치 성능입증을 위한 낙하시험)

  • Shin, Jeong-Woo;Lee, Seung-Gyu;Yang, Jin-Yeol;Kim, Sung-Joon;Hwang, In-Hee;Chung, Sang-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.250-254
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    • 2011
  • Main role of landing gear is to absorb the energy which is generated by aircraft lanidng and ground maneuvering. Generally, in order to absorb the impact energy during landing, oleo-pneumatic type shock absorber is used for aircraft landing gear. Oleo-pneumatic type shock absorber has a good energy absorbing efficiency and is light in weight because its structure is relatively simple. For the landing gear development, it is necessary to conduct drop test in order to verify shock absorbing performance. In the drop test, first, gas spring curve verification tests are conducted. Then, limit and reserve energy absorption drop tests are performed based on the STANAG 4671. The drop tests results with performance analysis results are presented.

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The Analysis and the Qualification Test Procedures for Oleo-pneumatic Landing Gear (유공압 착륙장치 해석 및 시험평가)

  • Kim, Tae-Uk;Lee, Sang-Wook;Kim, Sung-Chan
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.2
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    • pp.7-12
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    • 2012
  • A landing gear absorbs the impact energy during the touchdown and it generally consists of an oleo-pneumatic shock absorber and structural components. It should be designed not only to satisfy the static and fatigue strength requirements but to have the sufficient shock absorbing efficiency. The design loads and shock absorbing performance are to be validated by tests, which is required by MIL Spec and FAR, etc. This paper presents the development procedures from the design requirements to the qualification tests and technical points to be considered, with examples of the helicopter landing gear development.

Phytochemical Analysis and Anti-cancer Investigation of Boswellia Serrata Bioactive Constituents In Vitro

  • Ahmed, Hanaa H;Abd-Rabou, Ahmed A;Hassan, Amal Z;Kotob, Soheir E
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.16
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    • pp.7179-7188
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    • 2015
  • Cancer is a major health obstacle around the world, with hepatocellular carcinoma (HCC) and colorectal cancer (CRC) as major causes of morbidity and mortality. Nowadays, there isgrowing interest in the therapeutic use of natural products for HCC and CRC, owing to the anticancer activity of their bioactive constituents. Boswellia serrata oleo gum resin has long been used in Ayurvedic and traditional Chinese medicine to alleviate a variety of health problems such as inflammatory and arthritic diseases. The current study aimed to identify and explore the in vitro anticancer effect of B. Serrata bioactive constituents on HepG2 and HCT 116 cell lines. Phytochemical analysis of volatile oils of B. Serrata oleo gum resin was carried out using gas chromatography-mass spectrometry (GC/MS). Oleo-gum-resin of B. Serrata was then successively extracted with petroleum ether (extract 1) and methanol (extract 2). Gas-liquid chromatography (GLC) analysis of the lipoidal matter was also performed. In addition, a methanol extract of B. Serrata oleo gum resin was phytochemically studied using column chromatography (CC) and thin layer chromatography (TLC) to obtain four fractions (I, II, III and IV). Sephadex columns were used to isolate ${\beta}$-boswellic acid and identification of the pure compound was done using UV, mass spectra, $^1H$ NMR and $^{13}C$ NMR analysis. Total extracts, fractions and volatile oils of B. Serrata oleo-gum resin were subsequently applied to HCC cells (HepG2 cell line) and CRC cells (HCT 116 cell line) to assess their cytotoxic effects. GLC analysis of the lipoidal matter resulted in identification of tricosane (75.32%) as a major compound with the presence of cholesterol, stigmasterol and ${\beta}$-sitosterol. Twenty two fatty acids were identified of which saturated fatty acids represented 25.6% and unsaturated fatty acids 74.4% of the total saponifiable fraction. GC/MS analysis of three chromatographic fractions (I,II and III) of B. Serrata oleo gum resin revealed the presence of pent-2-ene-1,4-dione, 2-methyl- levulinic acid methyl ester, 3,5- dimethyl- 1-hexane, methyl-1-methylpentadecanoate, 1,1- dimethoxy cyclohexane, 1-methoxy-4-(1-propenyl)benzene and 17a-hydroxy-17a-cyano, preg-4-en-3-one. GC/MS analysis of volatile oils of B. Serrata oleo gum resin revealed the presence of sabinene (19.11%), terpinen-4-ol (14.64%) and terpinyl acetate (13.01%) as major constituents. The anti-cancer effect of two extracts (1 and 2) and four fractions (I, II, III and IV) as well as volatile oils of B. Serrata oleo gum resin on HepG2 and HCT 116 cell lines was investigated using SRB assay. Regarding HepG2 cell line, extracts 1 and 2 elicited the most pronounced cytotoxic activity with $IC_{50}$ values equal 1.58 and $5.82{\mu}g/mL$ at 48 h, respectively which were comparable to doxorubicin with an $IC_{50}$ equal $4.68{\mu}g/mL$ at 48 h. With respect to HCT 116 cells, extracts 1 and 2 exhibited the most obvious cytotoxic effect; with $IC_{50}$ values equal 0.12 and $6.59{\mu}g/mL$ at 48 h, respectively which were comparable to 5-fluorouracil with an $IC_{50}$ equal $3.43{\mu}g/mL$ at 48 h. In conclusion, total extracts, fractions and volatile oils of B. Serrata oleo gum resin proved their usefulness as cytotoxic mediators against HepG2 and HCT 116 cell lines with different potentiality (extracts > fractions > volatile oil). In the two studied cell lines the cytotoxic acivity of each of extract 1 and 2 was comparable to doxorubicin and 5-fluorouracil, respectively. Extensive in vivo research is warranted to explore the precise molecular mechanisms of these bioactive natural products in cytotoxicity against HCC and CRC cells.

Impact Analysis of Oleo-pneumatic Nose Strut for Light Aircraft (소형항공기 올레오 타입 전방착륙장치 충격해석)

  • Park, Ill-Kyung;Choi, Sun-Woo;Jang, Jae-Won
    • Aerospace Engineering and Technology
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    • v.6 no.1
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    • pp.19-28
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    • 2007
  • In this study, a nonlinear 2 degree of freedom mathematical model has been developed for impact analysis of the nose landing gear of a light aircraft which is composed of an wheel & tire, an Oleo-pneumatic shock strut and the castering wheel fork for the differential braking steering, and then the response of impact is computed using a numerical method. The mathematical model of a nose landing gear contains nonlinear characteristics which are an impact load - deflection property of a tire and internally frictional forces between an inner surface of an upper cylinder and a bearing of a lower rod due to side forces like the declined angle of strut, the moment due to an wheel fork, the side drag due to a steering and it is computed using the 4th-order Runge-Kutta method. The comparison process between analytical results and experimental results of the other proven nose landing gear is carried out to verify the mathematical model.

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