• 대한기계학회논문집A
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• 제27권6호
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• pp.1028-1033
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• 2003

The purpose of this paper is to investigate the noise and vibration characteristics of externally pressurized air journal bearings with a circular slot restrictor. To do this, the nonlinear transient analysis including rotor imbalance was performed for a rotor-bearing system. The effects of radial clearance and the length of the bearing and mass eccentricity of the rotor on the noise and vibration characteristics of the bearing are also examined. The results show that the noise and vibration of the rotor-bearing system first increase up to critical speed of the system, and then decrease up to instability threshold speed of the system as the rotational speed of the rotor increases, and the noise of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the length of the bearing.

• Osteoporosis and Sarcopenia
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• 제3권3호
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• pp.117-122
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• 2017

Sarcopenia is the degenerative loss of muscle mass and function with aging. Recently sarcopenia was recognized as a clinical disease by the International Classification of Disease, 10th revision, Clinical Modification. An imbalance between protein synthesis and degradation causes a gradual loss of muscle mass, resulting in a decline of muscle function as a progress of sarcopenia. Many mechanisms involved in the onset of sarcopenia include age-related factors as well as activity-, disease-, and nutrition-related factors. The stage of sarcopenia reflecting the severity of conditions assists clinical management of sarcopenia. It is important that systemic descriptions of the disease conditions include age, sex, and other environmental risk factors as well as levels of physical function. To develop a new therapeutic intervention needed is the detailed understanding of molecular and cellular mechanisms by which apoptosis, autophagy, atrophy, and hypertrophy occur in the muscle stem cells, myotubes, and/or neuromuscular junction. The new strategy to managing sarcopenia will be signal-modulating small molecules, natural compounds, repurposing of old drugs, and muscle-specific microRNAs.

• Tribology and Lubricants
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• 제34권1호
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• pp.9-15
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• 2018

Modern high-performance automotive turbochargers (TCs) implement ceramic hybrid angular contact ball bearings in series with squeeze film dampers (SFDs) to enhance transient responses, thereby reducing the overall emission levels. The current study predicts the rotordynamic responses of the commercial automotive TCs (compressor wheel diameter = ~53 mm, turbine wheel diameter = ~43 mm, and shaft diameter at the bearing locations = ~7 mm) supported on ball bearings and SFDs for various design parameters of SFDs, including radial clearance, axial length, lubricant viscosity, and rotor imbalance conditions (i.e., amplitudes and phase angles) while increasing rotor speed up to 150 krpm. This study validates the predictive rotor finite element model against measurements of mass, polar and transverse moments of inertia, and free-free mode natural frequencies and mode shapes. A nonlinear rotordynamic model integrates nonlinear force coefficients of SFDs to calculate the transient responses of the TC rotor-bearing system. The predicted results show that SFD radial clearances, as well as phase angles of rotor imbalances, have the paramount effect on the dynamic responses of TC shaft motions.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1993년도 제27차 학술대회 초록집
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• pp.71-71
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• 1993

이중음성이란 성대진동이 정상이 아닌 유사주기성에 의해 양측 성대진동의 위상차이때문에 발생되는 소리로서 대표적으로 양측성대의 긴장불균형(tension imbalance)시와 양측성대 사이의 높이차이(level difference)시에 발성직전의 성문열림의 정도에 따라 성대진동의 주기가 서로 다르기 때문에 이중음성이 발생한다고 한다. 그러나 실제 이러한 현상은 일측성대 마비환자뿐 아니라 성대의 점막부위에 증가된 질량효과에 의해 이중음성이 나타날 수 있는데 대표적으로 성대내 낭종이라 하겠다. 본 연구에서는 청각적으로 이중음성을 나타낸 일측성대마비, 성대내낭종 및 성대육아종 등 수술을 받았던 19례를 대상으로 음향학적 분석중 음성파형을 이용한 분석을 한 결과 유사주기성 음성파형에 대한 특징들중에서 파형수, peak변이도, 잡음의 정도등이 각질환에 따라 다른 양상을 보여 이중음성의 발생기전이 질환에 따라 다름을 알 수 있었다.

• 열처리공학회지
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• 제33권6호
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• pp.303-309
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• 2020

A vehicle's differential gear is a device designed to allow the vehicle's outer wheels to turn faster than the inner wheels when turning on a curve. The differential gear case is the main component of the differential gear system, which is composed of ring gear, pinion gear and side gear, and is fastened by pinion shaft pins. The differential gear case rotates when the vehicle is running, so balancing calibration is very important. In this study, a balancing machine that can diagnose and correct the differential gear case and mass imbalance of various rotating bodies was designed. The differential gear case was rotated at high speed to accurately diagnose the location and value of the unbalanced mass, and it was designed to be balanced and corrected by removing the unbalanced mass by drilling. After calibration, it was confirmed that the unbalanced value of all the measured samples was reduced to less than 180g.mm, and the unbalance reduction ratio was improved to 60~70%.

• 식품보건융합연구
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• 제8권2호
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• pp.15-27
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• 2022

This study aims to analyze the relative importance of bone age and chronological age in physique according to gender and to identify the relative importance of bone age, chronological age, and physique in physical fitness and motor coordination according to gender in order to alleviate the imbalance between physique and physical fitness in children. A total of 666 children(346 males, 320 females) between the ages of 11-14 were enrolled as subjects, and the skeletal maturation The skeletal maturation were measured by taking hand-wrist. Physical fitness were measured through a total of 4 components: muscular strength. The results of this study. First, physique variables for both males and females aged 11-14 were found to be more significant predictors of bone age than chronological age. Second, for physical fitness in males, in the order of %fat, body water, waist-hip ratio, weight, fat-free mass, and chronological age were more significant predictor variables; and in females, in the order of %fat, fat-free mass, height, chronological age, weight, bone age, fat mass, and body water were more significant predictor variables. For bone age and chronological age in physical fitness, bone age in males and chronological age in females found to be the more representative variables respectively.

• 항공우주시스템공학회지
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• 제1권3호
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• pp.32-36
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• 2007

When the reaction wheel rotates, the disturbance occurs mainly due to the mass imbalance. It is necessary to predict the effect of disturbance on the attitude stability of the satellite. The disturbance forces and torques are identified and the attitude jitter of the satellite is analyzed depending on the configuration of the wheels. On the analysis the equation of the satellite motion is combined with the translational and rotational dynamics of the wheels. The accuracy of analysis is verified by simulation of STSAT-3 satellite.

• 한국정밀공학회지
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• 제22권9호
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• pp.173-178
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• 2005

Recently plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing mold that has geometrically balanced runner lay-out for filling balance at each cavity. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in the cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS and PMMA as amorphous polymer, PA as crystalline polymer were used to compare the filling imbalances. There were different results of CAE and experiment. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.598-601
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• 2005

Plastic parts are molded for the purpose of mass production in multi-cavity system. Therefore, designer is usually designing molds that has geometrically balanced runner lay-out for filling balance at each cavities. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this study, based on previous studies for filling imbalances in cold-runner mold, filling imbalances in hot-runner mold were investigated by CAE and injection molding experiments. ABS, PMMA as amorphous polymer and PA, PP as crystalline polymer were used to compare the filling imbalances. The filling imbalances decreased as injection rate increased without regard to kind of resins and were lower than the one of cold-runner.

• Journal of Chest Surgery
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• 제14권3호
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• pp.225-227
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• 1981

A 31-year-old female visited O.P.D. of internal medicine, Kyung Hee Medical center, with the chief complaint of generalized weakness and headache. She took a routine chest P-A and there was a 6.5 x 7.5 cm sized round mass in the right middle lung field. She admitted to the Dept. of Thoracic and Cardiovascular Surgery under the impression of malignant bronchogenic carcinoma with the remit of bronchoscopy and sputum cytology and tomogram. Middle and lower lobectomy of right lung was performed and postoperative surgical biopsy revealed out the plasma cell granuloma. The plasma cell granuloma may occur as a solitary nodule in the lung or be associated with systemic disease, plasma protein imbalance, or nonspecific local inflammatory reaction . More than two third of the reported patients were less than 30 year of age. Grossly the lesion appears reddish-brown and microscopic features include pallisade or a cartwheel distribution of plasma cells with Russel bodies and amyloid. Local excision or lobectomy has been curative in most cases.