• Journal of Ecology and Environment
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• 제35권3호
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• pp.213-225
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• 2012

Sap flux density (SFD) measurements were used, in combination with morphological characteristics of trees and forest structure, to calculate whole-tree transpiration, stand transpiration (St) and mean canopy stomatal conductance (Gs). Analysis based on the relationships between the morphological characteristics of trees and whole tree water use, and on the responses of SFD and Gs to short wave radiation (RR), vapor pressure deficit (VPD) and soil water content (SWC) during drought and non-drought periods were conducted. The results showed a strong positive correlation between whole tree transpiration and both tree diameter at breast height (DBH) ($r^2$ = 0.95, P < 0.05) and sapwood area (SA) ($r^2$ = 0.98, P < 0.05). Relationships between SFD and DBH ($r^2$ = 0.25), as well as SA ($r^2$ = 0.17) were weak. Daily SFD of Quercus serrata Thunb was closely related to VPD and RR. Although operating at different time scales, RR and VPD were important interacting environmental controls of tree water use. SFD increased with increasing VPD (<1 kPa) and RR. SWC had a considerable effect on stand transpiration during the drought period. The relationships between SFD, VPD and RR were distorted when SWC dropped below 35%.

• 대한지역사회영양학회지
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• 제29권2호
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• pp.129-143
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• 2024

Objectives: The objective of this study is to compare a nutritionally balanced soft blend diet (SBD) with a soft fluid diet (SFD) on the health of inpatients who have undergone oral and maxillofacial (OMF) surgery, ultimately aiming to enhance care outcomes, improve health-related quality of life (QOL), and increase satisfaction with the hospital. Methods: Thirty-two patients were randomized into two groups: sixteen received SFD and sixteen received SBD. Anthropometric, laboratory evaluations were conducted upon admission and discharge. Patients filled out questionnaires on demographics, diet satisfaction, food intake amount, and health-related QOL on the day of discharge, assessed using the EuroQoL 5 Dimensions 3 Level and EuroQoL Visual Analogue Scale (EQ-VAS) instruments. Data were analyzed with descriptive statistics, χ² tests for group differences, and paired nonparametric t-tests for within-group comparisons. The Mann-Whitney U test evaluated inter-group differences in preoperative weight and body mass index (BMI), postoperative changes, meal satisfaction, intake, health-related QOL, and self-assessed health status. P-values were set at a significance level of 0.05. Results: The SBD group had higher dietary intake (63.2% vs. 51.0%) and greater diet satisfaction (80.6 vs. 48.1, P < 0.0001) compared to SFD group. Health-related QOL, measured by EQ-VAS, was better in SBD group (70.3 vs. 58.8, P < 0.05). Postoperative weight and BMI decreased in SFD group but increased in SBD group (P < 0.01). Changes in laboratory results showed more stability in the SBD group. No postoperative infections were reported in SBD group, whereas SFD group had a 31.25% complication rate. Conclusions: While SFD is often recommended after OMF surgery to protect oral wound healing process, our study reveals that SBD not only enhances physical and psychological outcomes but also, somewhat unexpectedly, supports wound healing and reduces complications. Essentially, SBD promotes physical recovery and enhances health-related QOL than SFD by supporting both somatic and mental healing aspects.

• Tribology and Lubricants
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• 제16권3호
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• pp.157-165
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• 2000

A discharge free Electro-Rheological Squeeze Film Damper (ER-SFD) with predetermined-clearances at leakage ends can inherently eliminate electric discharge problems while still supplying stable leakage control. Test results show that the damping force of the slotted-ring ER-SFD is mainly affected by electric voltage, oil supply pressure, position of the damper and ratio of effective surface area of slotted-rings. As the supply voltage is larger, the amplitudes of both slotted ER-SFD and rotor are decreased at first and second critical speeds. The influence of the oil supply pressure and the effective surface area ratio was shown mainly near the first critical speed. The effective surface area ratio of slotted-rings influences the reduction of flexible rotor vibration. As a result, experimental results confirm that the slotted-ring ER-SFD satisfactorily controls the flexible rotor vibration, while eliminates the inherent electric discharge problems in conventional ER-SFDs.

• Tribology and Lubricants
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• 제34권1호
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• pp.33-41
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• 2018

This paper describes a new test rig for identification of rotordynamic force coefficients of squeeze film dampers (SFDs) in automotive turbochargers (TCs). Prior studies have mainly concentrated on relatively large-sized SFDs used in aircraft engines, turbocompressors, and turbopumps. The main objective of the current study is to propose a test rig for identification of dynamic force coefficients of small-sized SFDs (a journal diameter of ~11 mm). The current test rig consists of a journal, a SFD cartridge, four support rods, an upper structure, a data acquisition (DAQ) system, and an oil circulation unit. The annular gaps between the journal outer surface and SFD cartridge inner surface create SFD film lands. The damper has two parallel film lands separated by a central groove, having an axial length and depth of 3 mm. Each film land has a length of 4 mm with a $40{\mu}m$ radial clearance. The static load and dynamic impact tests identify the structural characteristics (i.e., stiffness and natural frequency) of the journal and assembled test rig. The measurements show good agreement with predictions. The SFD performance data from this test rig will be used to develop innovative TC rotor systems with improved NVH and reliability characteristics incorporating advanced SFD technology.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1938-1948
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• 2003

This paper represents that an enhanced genetic algorithm (EGA) is applied to optimal design of a squeeze film damper (SFD) to minimize the maximum transmitted load between the bearing and foundation in the operational speed range. A general genetic algorithm (GA) is well known as a useful global optimization technique for complex and nonlinear optimization problems. The EGA consists of the GA to optimize multi-modal functions and the simplex method to search intensively the candidate solutions by the GA for optimal solutions. The performance of the EGA with a benchmark function is compared to them by the IGA (Immune-Genetic Algorithm) and SQP (Sequential Quadratic Programming). The radius, length and radial clearance of the SFD are defined as the design parameters. The objective function is the minimization of a maximum transmitted load of a flexible rotor system with the nonlinear SFDs in the operating speed range. The effectiveness of the EGA for the optimal design of the SFD is discussed from a numerical example.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.342.1-342
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• 2002

In this work, the dynamic characteristics of an oil-lubricated, short SFD with a central feeding groove are derived based on a theoretical analysis considering the effect of a groove. The validity of the analysis is investigated experimentally using an Active Magnetic Bearing (AMB) system as an exciter. For the theoretical solution, the fluid film forces of a grooved SFD are analytically derived so that the dynamic coefficients of a SFD are expressed in terms of its design parameters. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1286-1291
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• 2000

A new electro-rheological squeeze film damper (ER SFD) has been sealed with slotted piston rings which have electrodes at the inside of the constant gap. The slotted ER SFD can prevent the problem of electric discharge which might be occurred in the previous configuration of an ER SFD. The current paper presents the extraction of linearized dynamic coefficients within small orbit where these coefficients are controlled by the application of electric strength. Test rig has been modified to isolate the damper section for dynamic coefficient extraction. The results show that rotordynamic coefficients, damping and inertia terms, increase with increasing supply voltages, while stiffness coefficients decrease with increasing supply voltages. Rotating speed of rigid Shaft does not affect these coefficients.

• 한국안전학회지
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• 제12권1호
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• pp.9-18
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• 1997

This paper is a study on the dynamic characteristics of truncated cone type squeeze film damper(SFD) bearing and rotor system. This model can alter the radial oil film gap which Is Important to the performance of rotor-bearing system and manufactured easily to change the shape concept of traditional circular type SFD bearing. In theoretical analysis, the oil film pressure distribution, the oil film force, the film damping coefficient and the eccentricity ratio, etc. were induced with regard to the film inertia effect. The film damping coefficients and optimum design parameters are calculated. When unbalance parameter U is greater than 0.2, the nonlinear vibration such as "Jump" phenomena appears in the vicinity of rotor critical speed. At this time, the increases of bearing parameter U, journal distance S, Reynolds number Re can control this unstable vibration. The experimental results show that SFD hearing and rotor system which are designed according to the design parameters in the stable region are operated stably in rotational speed 9,600rpm without nonsynchronous behavior.

• 소음진동
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• 제10권6호
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• pp.1029-1034
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• 2000

A new electro-rheological squeeze film damper (ER-SFD) has been sealed with slotted piston rings which have electrodes at the inside of the constant gap. The slotted ER-SFD can prevent the problem of electric discharge which might be occurred in the previous configuration of an ER-SFD. The current paper presents the extraction of linearized dynamic coefficients within small orbit where these coefficients are controlled by the application of electric strength. Test rig has been modified to isolate the damper section for dynamic coefficient extraction. The results show that rotordynamic coefficients, damping and inertia terms, increase with increasing supply voltages, while stiffness coefficients decrease with increasing supply voltages. notating speed of rigid shaft does not affect these coefficients.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1662-1665
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• 2002

This paper proposes a novel semantic feature detection (SFD) method for real-time image transmission of sign language and finger spelling. We extract semantic information as an interlingua from input text by natural language processing, and then transmit the semantic feature detection, which actually is a parameterized action representation, to the 3-D articulated humanoid models prepared in each client in remote locations. Once the SFD is received, the virtual human will be animated by the synthesized SFD. The experimental results based on Japanese sign langauge and Chinese sign langauge demonstrate that this algorithm is effective in real-time image delivery of sign language and finger spelling.