피부사상균의 항진균제 감수성 검사

문석기,신동훈,최종수,김기홍,김극준 대한의진균학회 2008 대한의진균학회지 Vol.13 No.2

Background: A standardized reference method for dermatophytes in vitro susceptibility testing is lacking. However, with increasing variety of drugs available to treat dermatophytosis, the need for a reference method for dermatophytes testing has become apparent. Objective: To evaluate a method of quantifying dermatophytes, the standards for broth microdilution method and evaluation of the availability of disk diffusion method in antifungal susceptibility testing for dermatophytes. Methods: 14 Candida species (sp.), 30 Trichophyton(T.) mentagrophytes, 9 T. raubitschekii and 11 T. rubrum were tested for fluconazole susceptibility by the broth microdilution method and disc diffusion method. Candida sp. was tested according to National Committee for Clinical Laboratory Standards (NCCLS) M27-A and M44-A. Broth microdilution method for T. mentagrophytes, T. raubitschekii and T. rubrum was operated according to NCCLS M38-A. Disk diffusion method for T. mentagrophytes, T. raubitschekii and T. rubrum was tested refer to NCCLS M44-A. Result: The disk diffusion method showed 50% correlation rate with the broth microdilution method for antifungal susceptibility testing for Candida species. The MIC reading point and incubation time of the broth microdilution method for T. mentagrophytes, T. raubitschekii and T. rubrum are Spec-50 and from 7, 6 and 9 days. Relation between the broth microdilution method and disk diffusion method for dermatophytes is poor. Conclusions: The good method for quantifying dermatophytes is using vortexing only or liquid nitrogen and homogenizer. Standards of MIC reading point and incubation time of microdilution method for dermatophytes are Spec-50 and from 6 to 9 days. It appears that the disk diffusion method is not recommended method for the antifungal susceptibility testing of dermatophytes. Background: A standardized reference method for dermatophytes in vitro susceptibility testing is lacking. However, with increasing variety of drugs available to treat dermatophytosis, the need for a reference method for dermatophytes testing has become apparent. Objective: To evaluate a method of quantifying dermatophytes, the standards for broth microdilution method and evaluation of the availability of disk diffusion method in antifungal susceptibility testing for dermatophytes. Methods: 14 Candida species (sp.), 30 Trichophyton(T.) mentagrophytes, 9 T. raubitschekii and 11 T. rubrum were tested for fluconazole susceptibility by the broth microdilution method and disc diffusion method. Candida sp. was tested according to National Committee for Clinical Laboratory Standards (NCCLS) M27-A and M44-A. Broth microdilution method for T. mentagrophytes, T. raubitschekii and T. rubrum was operated according to NCCLS M38-A. Disk diffusion method for T. mentagrophytes, T. raubitschekii and T. rubrum was tested refer to NCCLS M44-A. Result: The disk diffusion method showed 50% correlation rate with the broth microdilution method for antifungal susceptibility testing for Candida species. The MIC reading point and incubation time of the broth microdilution method for T. mentagrophytes, T. raubitschekii and T. rubrum are Spec-50 and from 7, 6 and 9 days. Relation between the broth microdilution method and disk diffusion method for dermatophytes is poor. Conclusions: The good method for quantifying dermatophytes is using vortexing only or liquid nitrogen and homogenizer. Standards of MIC reading point and incubation time of microdilution method for dermatophytes are Spec-50 and from 6 to 9 days. It appears that the disk diffusion method is not recommended method for the antifungal susceptibility testing of dermatophytes.

Three methods for studying coupled vibration in a multi flexible disk rotor system

YiJui Chiu,Xiao-Yun Li,Yi-Cheng Chen,Sheng-Rui Jian,Chia-Hao Yang,I-Hsiang Lin 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

This paper improved and developed Shaft-disk-blade (SDB) rotor system based on the previous studies of the authors in the last decade from Yang and Huang (2005) to Chiu et al. (2017). This paper also explored blade-bending, disk-transverse, and shaft-torsion coupling vibration of a multi flexible disk rotor system. Unlike the previous studies of the authors, this paper adopted three methods: (a) Assumed mode method (AMM), (b) Finite element method (FEM), and (c) experimental method. The first approach is the main method, and the two other methods are complementary. Results generated from the three methods were then compared and analyzed. Based on the previous definition of the authors, a flexible disk rotor system displays three types of coupling vibrations: Inter-blade, SDB, and diskblade modes. The system changes the rules of natural frequencies and mode shapes. This paper presents several interesting results. First, the author determined the change rules of the mode shapes and natural frequencies using the AMM, FEM (including three kinds of software), and the experimental method. Second, numerical calculation results also revealed that two phenomena regarding the distance of disk and flexible disk would be affected by the natural frequencies. Third, the experimental results would be explored in this paper. Last, the flexible disk could affect the system instability in the case study of rotation effects.

고속 회전 유연 디스크의 진동 저감용 공기 베어링 해석

이성호(Sung-ho Lee),임윤철(Yoon-chul Rhim) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.39 No.-

Rotating disks are used in various machines such as data storage device, gyroscope, circular saw, etc. Transverse vibration of a rotating disk is very important for the performance of these machines. This work proposes a method to suppress transverse vibration of a very flexible rotating disk in non-contacting manner. A system considered in this study is a very flexible rotating disk with a thrust bearing pad which is located underneath the rotating disk. The pressure force generated in the gap between the rotating disk and the thrust pad pushes the rotating disk in the direction of axis of rotation while the centrifugal force and the elastic recovery force push the rotating disk in reverse direction. The balance between these forces suppresses the transverse vibration of the rotating disk. A coupled disk-fluid system is analyzed numerically. The finite element method is used to compute the pressure distribution between the thrust pad and the rotating disk while the finite difference method is used to compute the transverse vibration of a rotating disk. Results show that the transverse vibration of the rotating disk can be suppressed effectively for certain combination of air bearing and operating parameters.

디스크 브레이크와 패드의 마찰열에 의한 열적거동에 관한 연구

한승철 한국융합학회 2019 한국융합학회논문지 Vol.10 No.12

This paper analyzes the thermal behaviors of genuine discs used in automobiles and discs coming out of tuning products through FEM analysis. Modeling with genuine disk modeling and tuning disks Model-1, Model-2, Model-3 and analyzing the disk rotation speed was set to 1000rpm. When the brake is operated, the thermal behavior of the disk surface, such as the operating temperature caused by the disk and pad contact, the friction surface temperature after the disk stop, and the thermal deformation, were analyzed. When the brake was activated (0-4.5 seconds), the tuning disk showed 34℃ higher than the original disk, and after the disk stopped (40.5 seconds), the tuning disk was analyzed 18℃ lowe, deformation due to the disk heat was deformed by 0.3mm for the tuning disk. Although there is an effect to reduce the fading phenomenon due to the thermal behavior of the pure disk and the tuning disk, it can be observed that there is no significant change in the thermal behavior due to the hole processing and the disk surface processing of the tuning disk. 본 논문은 자동차 제동성능에 대한 운전자의 요구에 따라 브레이크 디스크 튜닝이 많이 이루어지고 있어, 자동차에 사용되고 있는 순정 디스크와 튜닝제품으로 나오고 있는 디스크의 열적거동을 FEM해석을 통해 분석하였다. 순정 디스크 모델링 및 튜닝 디스크 Model-1, Model-2, Model-3로 모델링을 하고 디스크 회전속도를 1000rpm으로 설정하여 해석을 실시하였다. 브레이크를 작동하면 디스크와 패드 접촉에 의해 발생하는 작동시 온도와 디스크 정지 후 마찰면의 온도, 열 변형 등 디스크 표면의 열적거동에 대하여 분석하였다. 브레이크 작동시(0-4.5초) 온도는 순정 디스크보다 튜닝 디스크가 34℃높게 나타났고, 디스크 정지 후(40.5초) 온도는 튜닝 디스크가 18℃낮게 분석되었으며, 디스크 열에 의한 변형은 튜닝 디스크가 0.3mm정도 많이 변형되었다. 순정 디스크와 튜닝 디스크의 열적거동에 따른 페이드현상 등을 줄일 수 있는 효과는 있으나, 튜닝 디스크의 홀 가공 및 디스크 면 가공에 따른 열적거동에는 크게 변화가 없음을 관찰할 수 있었다.

THE WARPED DISK OF INTEGRAL-SIGN GALAXY PGC 20348

Ann, H.B. The Korean Astronomical Society 2007 Journal of The Korean Astronomical Society Vol.40 No.1

We examine the morphology and luminosity distribution of a strongly warped spiral galaxy PGC 20348 by conducting a detailed BVI CCD surface photometry using BOAO 1.8m telescope. The radial surface brightness shows a break at warp radius $(r_{\omega})$ with a shallow gradient in the inner disk and a steeper gradient in the outer disk. The luminosity of east side of the disk is ${\sim}0.5$ mag fainter than the west side at r > $r_{\omega}$. The reason for the asymmetric luminosity distribution is thought to be the asymmetric flarings that result in the formation of a large diffuse region at the edge of the east disk and a smaller diffuse region at the west disk. The vertical luminosity profiles show a thick disk component whose scale heights increase with increasing galactocentric distances. The warp of PGC 20348 seems to be made by the tidal interactions with the two massive companion galaxies since the flarings and radial increase of disk scale heights are thought to be general properties of tidally perturbed disks. According to the colors of the two clumps inside the diffuse region at the edge of the east disk, they seem to be sites of active star formation triggered by tidal forces from the companion galaxies.

Vibration characteristics of computer stacked disks and head assembly

Shyh-Chin Huang,Kao-An Lin 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.3

A stacked multi-disk with read/write head assembly was investigated. The interference of head assembly on the spinning disks was modeled by stationary springs intervening between disks. The receptance method was then applied to join the spinning disks and the stationary springs. A general, recursive equation for natural frequency of a disk-head system was derived. Numerical examples followed for the cases of 3 to 6 stacked disks. The results showed that even for weak spring coupling, the changes of mode shapes were very significant and the changes of natural frequencies were slight. The effects of spring stiffness, location, and disk spinning speed were examined as well. The spinning speed was seen to pull the frequency loci to pass through the crossings of a single disk’s frequency curves and there existed a curve-veering phenomenon.

Application of the body force method in the rim driven thruster

Cai Boao,Tian Binbin,Qiu Liaoyuan,Xu Qing,Mao Xiaofei,He Wei,Chai Wei 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

The Rim Driven Thruster (RDT) has become a popular ship propulsion system in recent years. Due to the complex structure of RDT, a great number of computational resources are required to study the interaction between RDT and hull by adopting the discretized propeller method. This research looks into a modified body force method which is suitable for the RDT. To simulate self-propulsion of a trawler with a rim driven thruster, the Reynolds-averaged NaviereStokes (RANS) solver is used. In the modified body force method, three virtual disks are adopted to replace the propeller and rim rotors. Before correction, the interactions among the duct, the rim rotors and the propeller were studied. Through the analysis, it is found that the most suitable scheme is to take the open water curves of the propeller, of the “rotors þ duct” and of the RDT as the references for modification. The ducted virtual disks open water curve is modified in open water simulations until the result is consistent with the RDT open water calculation results. When used to self-propulsion simulation, the modified body force method is accurate and can roughly characterize the flow fields. The modified body force method saves a huge number of grids when compared to the discretized propeller method. Furthermore, the interaction between the ship and the RDT can be accurately modeled, which is critical for quickly predicting self-propulsion in ships equipped with rim driven thrusters. Finally, the modified body force method in this work is named as the body force RDT method.

A Sternum-Disk Distance Method to Identify the Skin Level for Approaching a Surgical Segment without Fluoroscopy Guidance during Anterior Cervical Discectomy And Fusion

이근우,안면환,신지훈,박재우,어재형,박종호,이지훈,김동욱,Jin S. Yeom,서보건 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.1

Study Design: A retrospective review of prospectively collected data. Purpose: To introduce the sternum-disk distance (SDD) method for approaching the exact surgical level without C-arm guidance during anterior cervical discectomy and fusion (ACDF) surgery and to evaluate its accuracy and reliability. Overview of Literature: Although spine surgeons have tried to optimize methods for identifying the skin level for accessing the operative disk level without C-arm guidance during ACDF, success has rarely been reported. Methods: In total, 103 patients who underwent single-level ACDF surgery with the SDD method were enrolled. The primary outcome measure was the accuracy of the SDD method. The secondary outcome measures were the mean SDD value at each cervical level from the cranial margin of the sternum in the neutral and extension positions of the cervical spine and the inter- and intra-observer reliability of the SDD outcome determined using repeated measurements by three orthopedic spine surgeons. Results: The SDD accuracy (primary outcome measure) was indicated in 99% of the patients (102/103). The mean SDD values in the neutral-position magnetic resonance imaging (MRI) were 108.8 mm at C3–C4, 85.3 mm at C4–C5, 64.4 mm at C5–C6, 44.3 mm at C6– C7, and 24.1 mm at C7–T1; and those in the extension-position MRI were 112.9 mm at C3–C4, 88.7 mm at C4–C5, 67.3 mm at C5–C6, 46.5 mm at C6–C7, and 24.3 mm at C7–T1. The Cohen kappa coefficient value for intra-observer reliability was 0.88 (excellent reliability), and the Fleiss kappa coefficient value for inter-observer reliability as reported by three surgeons was 0.89 (excellent reliability). Conclusions: Based on the results of the present study, we recommend performing ACDF surgery using the SDD method to determine the skin level for approaching the surgical cervical segment without fluoroscopic guidance.

Study on localization influences of frequency veering on vibration of mistuned bladed disk

Hongyuan Zhang,Huiqun Yuan,Wenjun Yang,Tianyu Zhao 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

Reduced-order models of the bladed disk of the aero-engine compressor were established by adopting Prestressed component mode synthesis (PCMS) method. The frequency veering characteristics of the tuned bladed disk were analyzed. From the aspect of the strain energy, the forced vibration response of the mistuned bladed disk was analyzed, along with calculation of the contribution degree factors, the localization factors and frequency veering distances, finding the influences of the frequency veering distance, the contribution degree factors and the localization. The results show that frequency veering has significant influence on vibration localization of the mistuned bladed disk; in the region of frequency veering, the degree of vibration localization of the mistuned bladed disk is relatively high; along with the changes of the frequency veering distance, the contribution degree of the strain energy of the blades of localization of the mistuned bladed disk shows the certainty of regularity.

Thermo-mechanical analysis of functionally graded wheel-mounted brake disk

Tohid Mahmoudi,Ali Parvizi,Esmaeil Poursaeidi,Abbas Rahi 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

Having higher speed for trains requires improvement in braking performances. The brake system is an important part of locomotivesafety system in which the mechanical energy is converted to the thermal energy and distributed through the disks and pads. As a result,the temperature at the disks surfaces increases sharply. This phenomenon is called the thermal shock that causes the negative effects onthe brake disk surface such as fast aging, early wear, thermal cracks and the brake fade. Using Functionally graded materials (FGMs)which are more resistant to the thermal shock is a new trend to deal with this issue. In this study, the effects of using FG materials in thewheel-mounted brake disk R920K for the ER24PC locomotive on its thermo-mechanical behavior are investigated. For this purpose, theuncoupled thermo-mechanical analysis is performed for the disk made of FG Al-A359/SiCp, aluminum and ductile cast iron materials. Comparing the results of brake disk made of ductile cast iron with those from experimental data, the accuracy of present FE model isverified. Concerning the stress analysis, it is shown that the safety factor for the disk made of FG material is higher than the other ones. Furthermore, the gradation index of FG material has the most important effect on the thermo-mechanical performance of FG disks.