• Title/Summary/Keyword: Effective Transfer Function

Search Result 213, Processing Time 0.038 seconds

Optimal Design Variables of a Parallel-Flow Heat Exchanger by Using a Desirability Function Approach (만족도 함수를 이용한 평행류 열교환기 설계인자 최적화)

  • Oh Seok-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.17 no.6
    • /
    • pp.587-595
    • /
    • 2005
  • The heat and flow characteristics in a parallel-flow heat exchanger were examined numerically to obtain its optimal design variables. A desirability function approach was introduced to optimize its performance with respect to the design parameters over the design domain. By varying the importance of heat transfer and pressure drop which are out put variables, the optimal values of the design parameters are examined. As a result, the us-age of the desirability function is very effective for the optimization of the design variables in a heat exchanger since the changes of optimal values are physically appropriate by varying the importance of each output variable.

Interior Noise Reduction of Wheel Loader Using Transfer Path Analysis and Panel Contribution Analysis (전달 경로 분석과 패널 기여도 분석을 이용한 휠로더의 실내소음 저감에 관한 연구)

  • Kim, Bo-Yong;Shin, Chang-Woo;Jeong, Won-Tae;Park, Sung-Yong;Jang, Han-Kee;Kim, Seong-Jae;Kang, Yeong-June
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.18 no.8
    • /
    • pp.805-815
    • /
    • 2008
  • Transfer path analysis(TPA) and panel contribution analysis(PCA) have been used widely to reduce interior noise of mechanical systems. TPA enables us to decompose interior noise into air-borne and structure-borne noises and estimate the path contribution of noise sources. PCA is also used to identify the noise contribution of each sub-panel in vibro-acoustic systems. In this paper, TPA and PCA are applied to wheel loader, one of the heavy construction equipments. Firstly, TPA for air-borne noise is conducted to estimate the contribution of air-borne sources using pressure transfer function. Thereafter, TPA for structure -borne noise is employed to verify the results of air-borne source quantification through the synthesis of two results. Secondly, PCA is performed by both TPA using pressure transfer function between panels inside the cabin and boundry element method(BEM) for the cabin of wheel loader with various boundary conditions. As a results, it was found that TPA conducted by experiments and PCA accomplished by both experiments and BEM are very effective methods in analyzing the path and contribution of the noises for reducing an interior noise level in the wheel loader system.

Facial reanimation using the hypoglossal nerve and ansa cervicalis: a short-term retrospective analysis of surgical outcomes

  • Koo, Won Young;Park, Seong Oh;Ahn, Hee Chang;Ryu, Soo Rack
    • Archives of Craniofacial Surgery
    • /
    • v.22 no.6
    • /
    • pp.303-309
    • /
    • 2021
  • Background: Transferring the hypoglossal nerve to the facial nerve using an end-to-end method is very effective for improving facial motor function. However, this technique may result in hemitongue atrophy. The ansa cervicalis, which arises from the cervical plexus, is also used for facial reanimation. We retrospectively reviewed cases where facial reanimation was performed using the ansa cervicalis to overcome the shortcomings of existing techniques of hypoglossal nerve transfer. Methods: The records of 15 patients who underwent hypoglossal nerve transfer were retrospectively reviewed. Three methods were used: facial reanimation with hypoglossal nerve transfer (group 1), facial nerve reanimation using the ansa cervicalis (group 2), and sural nerve interposition grafting between the hypoglossal nerve and facial nerve (group 3). In group 1, the ansa cervicalis was coapted to neurotize the distal stump of the hypoglossal nerve in a subset of patients. Clinical outcomes were evaluated using the House-Brackmann (H-B) grading system and Emotrics software. Results: All patients in group 1 (n= 4) achieved H-B grade IV facial function and showed improvements in the oral commissure angle at rest (preoperative vs. postoperative difference, 6.48° ± 0.77°) and while smiling (13.88° ± 2.00°). In groups 2 and 3, the oral commissure angle slightly improved at rest (group 2: 0.95° ± 0.53°, group 3: 1.35° ± 1.02°) and while smiling (group 2: 2.06° ± 0.67°, group 3: 1.23° ± 0.56°). In group 1, reduced tongue morbidity was found in patients who underwent ansa cervicalis transfer. Conclusion: Facial reanimation with hypoglossal nerve transfer, in combination with hypoglossal nerve neurotization using the ansa cervicalis for complete facial palsy patients, might enable favorable facial reanimation outcomes and reduce tongue morbidity. Facial reanimation using the ansa cervicalis or sural nerve for incomplete facial palsy patients did not lead to remarkable improvements, but it warrants further investigation.

Standardization of Maintenance and Failure of Transfer Crane (Transfer Crane의 고장 및 정비 표준화)

  • Yun Won-Young;Lee You-Hyoun;Ha Young-Ju;Kim Gui-Rae;Son Bum-Shin
    • Journal of Navigation and Port Research
    • /
    • v.30 no.6 s.112
    • /
    • pp.525-531
    • /
    • 2006
  • In the port, the yard crane is very important. If a container crane or a transfer crane is broken down, it costs a lot because of the delay of work during the period of repair or reorder. But, we don't have enough spare parts because of the high cost. It is necessary to maintain high reliability of the crane through effective preventive maintenance and failure analysis. In this paper, we analyse the function and failure mechanism of the transfer crane which is a main equipment in the yard Also, we standardize failures and maintenance works using the historical data of failure and maintenance. This study which is a basic work for effective equipment operation and maintenance will support reliability engineers to decide the optimal design of the next generation equipment and operational policy of equipment.

Performance Improvement Method of Multi-Port Memory Controller Using An Effective Multi-Channel Direct memory Access Management (효과적인 다채널 직접 메모리 접근 관리를 통한 멀티포트 메모리 컨트롤러의 성능 향상 방법)

  • Chun, Ik-Jae;Lyuh, Chun-Gi;Roh, Tae Moon;Lee, Moon-Sik
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.51 no.4
    • /
    • pp.33-41
    • /
    • 2014
  • This paper presents an effective memory access method for a high-speed data transfer on mobile systems using a direct memory access controller that considers the characteristics of a multi-port memory controller. The direct memory access controller has an integrated channel management function to control multiple direct memory access channels. The channels are physically separated and operate independently from each other. Experimental results show that the proposed direct memory access method improves the transfer performance by up to 72% and 69% on read and write transfer cycles, respectively. The total number of transfer cycles of the proposed method is 63% less than in a commercial method under 4-channel access.

Evaluation of the Filling Sodium States Inside the Fuel rod of Sodium-Cooled Fast Reactor by Optimized Spatial Resolution in Medical Digital Radiographic Images (의료용 디지털방사선영상의 공간분해능 최적화에 의한 소듐냉각고속로 연료봉 내부의 소듐 충전상태 평가)

  • Seoung, Youl-Hun
    • Journal of the Korean Society of Radiology
    • /
    • v.10 no.2
    • /
    • pp.117-124
    • /
    • 2016
  • The purpose of this study was tried to evaluate the filling sodium states inside the fuel rod of sodium-cooled fast reactor by digital medical X-ray. We used the diagnostic X-ray generators in digital radiography (DR). This study have found the optimal conditions by changing the effective focal spot size of X-ray tube and post-processing of the DR method with a tungsten edge plate in order to ensure excellent sharpness At this time, the sharpness and resolution were evaluated using the MTF (modulation transfer function). As a result, this study obtained a spatial resolution of 3.871 lp/mm (0.1 MTF), 3.290 lp/mm (0.5 MTF) when implemented the contrast strengthen post-processing in small focal spot. In this research, the result is able to evaluate the level of sodium inside the fuel rod by using the diagnostic X-ray generators in medical digital radiographic images.

Performance Compensation of the Satellite Imager below Normal Altitude Using Line-Of-Sight Tilt over Spherical Earth Surface (구면 지표에서 경사촬영을 이용한 위성 영상기의 고도 저하 성능 보정)

  • 조영민
    • Korean Journal of Remote Sensing
    • /
    • v.20 no.2
    • /
    • pp.117-124
    • /
    • 2004
  • A spherical earth surface is used for realistic analysis of the geometrical performance characteristics generated by 2-dimensional line-of-sight (LOS) tilt of the satellite imager using the Time Delay and Integration(TDI) technique. A 2-dimensional LOS tilt ever the spherical Earth surface is proposed to compensate geometric performance degradation caused by the satellite altitude decrease below the normal operation altitude. The compensation can be achieved by TDI re-match without degradation of modulation transfer function and with ground sample distance slightly increased. Effective methods of LOS tilt for the compensation are investigated. This study can be useful for mission assurance and flexibility in imager operation.

Investigation on the integrated transfer function characteristics for the buffeting response prediction of elongated structures

  • Yi Su;Mingshui Li;Jin Di;Yang Yang;Shaopeng Li
    • Wind and Structures
    • /
    • v.37 no.6
    • /
    • pp.399-412
    • /
    • 2023
  • Previous studies have shown that the integrated transfer function (ITF) is independent of turbulence characteristics and can be effectively applied to predict the buffeting response of elongated structures, assuming that the strip hypothesis is valid. However, existing research has not effectively identified the ITF through segment model vibration tests, and the influence of the 3D effect on the accuracy of the strip hypothesis and the characteristics of the ITF in wind tunnel tests has not been quantitatively studied. A segment model vibration measurement device that can change a test model's span-width ratio was designed in this study. An airfoil section and a streamlined box girder section structure were taken as the background, and their ITFs were effectively identified under different L/B (L denotes the turbulent integral scale and B denotes the structural width) and model span-width ratios. The influence laws of the 3D effect on the accuracy of the strip hypothesis and ITF identification in wind tunnel tests were systematically investigated. The results showed that L/B and the structural span-width ratio are two significant controlling factors that affect the accuracy of the strip hypothesis and ITF identification. The research provides an effective experimental method for accurately predicting the buffeting response of elongated structures based on ITFs identified through segment model vibration tests.

Prediction of the Diffusion Controlled Boundary Layer Transition with an Adaptive Grid (적응격자계를 이용한 경계층의 확산제어천이 예측)

  • Cho J. R.
    • Journal of computational fluids engineering
    • /
    • v.6 no.4
    • /
    • pp.15-25
    • /
    • 2001
  • Numerical prediction of the diffusion controlled transition in a turbine gas pass is important because it can change the local heat transfer rate over a turbine blade as much as three times. In this study, the gas flow over turbine blade is simplified to the flat plate boundary layer, and an adaptive grid scheme redistributing grid points within the computation domain is proposed with a great emphasis on the construction of the grid control function. The function is sensitized to the second invariant of the mean strain tensor, its spatial gradient, and the interaction of pressure gradient and flow deformation. The transition process is assumed to be described with a κ-ε turbulence model. An elliptic solver is employed to integrate governing equations. Numerical results show that the proposed adaptive grid scheme is very effective in obtaining grid independent numerical solution with a very low grid number. It is expected that present scheme is helpful in predicting actual flow within a turbine to improve computation efficiency.

  • PDF

Parallel Operation Method of Multi Function Rapid-Charger with an Active Power Filter (능동전력필터 기능을 갖는 다기능 준급속 충전기의 병렬운전 기법)

  • Bae, Sung-Hoon;Choi, Seong-Chon;Shin, Min-Ho;Song, Sang-Hoon;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
    • /
    • 2014.07a
    • /
    • pp.534-535
    • /
    • 2014
  • This paper proposes parallel operation of multi function rapid-charger with an active power filter. Rapid-charger can be installed in public institutions or mart parking lot. But conventional charger has disadvantage that it can not be used as the active power filter in charging mode with only one charger. So using 3-parallel operation, effective mode transfer between battery charging and APF function can obtain effect of harmonic compensation and improving the utilization of the charger.

  • PDF