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( Soohyun Bae ),( Kwang Won Seo ),( Soyeoun Lim ),( Jong Joon Ahn ),( Yangjin Jegal ),( Seung Won Ra ),( Taehoon Lee ),( Byung Ju Kang ),( Jin Hyoung Kim ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-
Background: Cavitary pulmonary tuberculosis (TB) is known to remain infectious for longer periods than non-cavitary pulmonary TB, which is nearly non-infectious with two weeks anti-TB medication. However, there is verly little studies about this, so it is not known whether there is a correlation between the persistence of infectiousness and the number of cavities or volume of cavities. Objectives: The purpose of this study was to identify the quantitative computed tomography features and clinical values to predict the presistence of infectiousness in cavitary TB patients. Method: A total of 304 TB patients were selected from the cohort of TB in Ulsan university hospital. The study subjects were classified into two groups according to the Acid-fast bacilli Ziehl-Neelsen staining in sputum. The two groups were compared with respect to demographic data, clinical characteristics, sputum AFB stain, mycobacterial culture and quantitative CT values. Results: Among 304 patients, 80 were enrolled for analysis. 43 patients (54%) were positive sputum AFB stains. Compared to negative sputum AFB stain group, the positive sputum AFB stain group had more systemic symptom and larger maximal size of cavity. Treatment duration for last culture positive was 37.9 ± 64.7 days (p = 0.01), which is significantly longer in AFB positive group. Conclusion: Cavitary lesion was associated with a infectiousness, more systemic symptom, longer duration of culture conversion. Quantitative analysis of CT showed that volume and size of cavities were associated with persistent infectiousness in TB patients.
공간 균일 오차 최소화가 가능한 위상 시프팅 알고리즘을 통한 광학 두께 변동량 측정
배원준(Wonjun Bae),김양진(Yangjin Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
Wavelength-tuning interferometry is an effective means of detecting the intensity signals necessary to obtain thickness information, particularly the optical thickness variation of transparent plates. The phase-shift error caused by the non-linearity of a phase-shift can lead to spatially uniform error. When the absolute optical thickness is measured, this could be a significant error source. In this study, we developed a new 19-sample phase-shifting algorithm that can suppress spatially uniform error and harmonic components up to the sixth order. Utilizing the Taylor expansion and symmetric/asymmetric properties, we created a new sampling window. The absence of an equation is solved by adjusting the first and second value of sampling window. Finally, the characteristics of the new 19-sample phase-shifting algorithm are shown by analyzing the Fourier transform of sampling functions, phase-dependent measurement errors, and the root mean square (RMS) error.
Corrugated cooling unit for accelerated cooling of rebar subjected to Tempcore process
Park, Chun Su,Bae, Seh Wook,Cho, Jin Rae,Lee, Habeom,Kim, Yangjin,Moon, Young Hoon Elsevier 2020 Applied thermal engineering Vol.167 No.-
<P><B>Abstract</B></P> <P>An advanced cooling unit was developed and characterized to accelerate the cooling of steel rebars during the Tempcore process. Compared to conventional flat-surfaced coolers, the newly developed cooling unit uses a corrugated surface to generate turbulence. To estimate the cooling performance of the corrugated cooler, the heat transfer coefficient during the Tempcore process was obtained using a finite-volume method. The turbulence induced by the corrugated cooler reduces the vapor volume fractions and increases the heat transfer coefficient by up to 10%. The obtained heat transfer coefficient for convective and nucleate boiling was then applied in the model to predict the volume of martensite formed in the outer layer of the bar after the Tempcore process. The corrugated cooling unit was assembled and incorporated into an experimental simulator to evaluate its ability to accelerate cooling of rebars. For rebars treated in the corrugated cooler, a 6.54% increase in the martensite volume fraction with a 13 °C decrease in the self-tempering temperature was achieved. This result confirms that the developed corrugated cooler can be a reasonable alternative to increase cooling efficiency of Tempcore facility without upgrading the capacity of the water supplying system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The turbulence induced by the corrugated cooler increases the cooling capacity. </LI> <LI> Heat transfer coefficient for convective and nucleate boiling is numerically obtained. </LI> <LI> RPI boiling model and realizable k-epsilon model are extended to the Tempcore process. </LI> <LI> 6.54% increase in the martensite volume fraction is achieved by the corrugated cooler. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>