섬유 및 혼화제를 이용한 황토 모르타르의 수축균열 제어

문주현(Mun Ju-Hyun),양근혁(Yang Keun-Hyeok),전중규(Jeon Joong-Kyu),황혜주(Hwang Hye-Zoo) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.8

A total of 8 hwang-toh mortar mixes with no cement were tested to evaluate the effect of different fibers and admixtures on the control of shrinkage cracks of such mortars. The fiber types added were Lyocell, Poly-Amid and PVA, while, CSA and organic polymer were selected as the admixture. The shrinkage crack resistance of hwang-toh mortar were examined from the unrestrained drying shrinkage strain, restrained drying shrinkage and plastic shrinkage. Test results revealed that the unrestrained drying shrinkage strain of hwang-toh mortar sharply increased at an early age showing approximately 2.5 times higher values than predictions obtained from ACI 209, regardless of the addition of fibers and admixtures. In addition, cracks owing to the restrained drying shrinkage developed at the only age of 1.6 days in all test mixes; as a result, the cracking grade of hwang-toh mortar was evaluated to be high. On the other hand, the addition of fibers required a value of fiber spacing above 0.0003 in order to enhance the tensile resistance capacity of hwang-toh mortar under the restrained drying shrinkage and reduce the cracking area under the plastic shrinkage. Overall, it could be concluded that moist curing at an early age and the addition of fiber with fiber spacing above 0.0003 are practically effective in reducing shrinkage crack of hwang-toh mortar.

서울의 PPNG 발생 빈도(1991-1992)

김재홍,윤기범,박평원,김영진,전경민,김영태,김중환,곽호,구상완,송민석,유옥,지혜구,김동원,문상은,박영립,정승호,성범진,성순제,엄주용,황정열,이기홍,이주협,전태진 대한화학요법학회 1994 대한화학요법학회지 Vol.12 No.1

The prevalence of PPNG among pretreated gonorrhea cases isolated at the STD clinic of Choong-Ku Public Health Center in Seoul has been studied and reported annually since 1981. In 1991, 123 strains of N.gonorrhoeae were isolated, among which 58(47.1%) were PPNG. In 1992, 98 starains of N.gonorrhoeae were isolated, among which 51(52.0%) were PPNG. In all, 109(49.3%) strains were found to be PPNG among 221 strains isolated between 1991-1992. The prevalence of PPNG in Seoul showed increased tendency till 1989, thereafter, it has been stationary or slightly decreasing.

Generative Adversarial Network-Based Image Conversion Among Different Computed Tomography Protocols and Vendors: Effects on Accuracy and Variability in Quantifying Regional Disease Patterns of Interstitial Lung Disease

Hwang Hye Jeon,Kim Hyunjong,Seo Joon Beom,Ye Jong Chul,Oh Gyutaek,Lee Sang Min,Jang Ryoungwoo,Yun Jihye,Kim Namkug,Park Hee Jun,Lee Ho Yun,Yoon Soon Ho,Shin Kyung Eun,Lee Jae Wook,Kwon Woocheol,Sun Jo 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.8

Objective: To assess whether computed tomography (CT) conversion across different scan parameters and manufacturers using a routable generative adversarial network (RouteGAN) can improve the accuracy and variability in quantifying interstitial lung disease (ILD) using a deep learning-based automated software. Materials and Methods: This study included patients with ILD who underwent thin-section CT. Unmatched CT images obtained using scanners from four manufacturers (vendors A-D), standard- or low-radiation doses, and sharp or medium kernels were classified into groups 1–7 according to acquisition conditions. CT images in groups 2–7 were converted into the target CT style (Group 1: vendor A, standard dose, and sharp kernel) using a RouteGAN. ILD was quantified on original and converted CT images using a deep learning-based software (Aview, Coreline Soft). The accuracy of quantification was analyzed using the dice similarity coefficient (DSC) and pixel-wise overlap accuracy metrics against manual quantification by a radiologist. Five radiologists evaluated quantification accuracy using a 10-point visual scoring system. Results: Three hundred and fifty CT slices from 150 patients (mean age: 67.6 ± 10.7 years; 56 females) were included. The overlap accuracies for quantifying total abnormalities in groups 2–7 improved after CT conversion (original vs. converted: 0.63 vs. 0.68 for DSC, 0.66 vs. 0.70 for pixel-wise recall, and 0.68 vs. 0.73 for pixel-wise precision; P < 0.002 for all). The DSCs of fibrosis score, honeycombing, and reticulation significantly increased after CT conversion (0.32 vs. 0.64, 0.19 vs. 0.47, and 0.23 vs. 0.54, P < 0.002 for all), whereas those of ground-glass opacity, consolidation, and emphysema did not change significantly or decreased slightly. The radiologists’ scores were significantly higher (P < 0.001) and less variable on converted CT. Conclusion: CT conversion using a RouteGAN can improve the accuracy and variability of CT images obtained using different scan parameters and manufacturers in deep learning-based quantification of ILD.

Visual and Quantitative Assessments of Regional Xenon-Ventilation Using Dual-Energy CT in Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome: A Comparison with Chronic Obstructive Pulmonary Disease

Hwang Hye Jeon,Lee Sang Min,Seo Joon Beom,Lee Jae Seung,Kim Namkug,Lee Sei Won,Oh Yeon-Mok 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.9

Objective: To assess the regional ventilation in patients with asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) using xenon-ventilation dual-energy CT (DECT), and to compare it to that in patients with COPD. Materials and Methods: Twenty-one patients with ACOS and 46 patients with COPD underwent xenon-ventilation DECT. The ventilation abnormalities were visually determined to be 1) peripheral wedge/diffuse defect, 2) diffuse heterogeneous defect, 3) lobar/segmental/subsegmental defect, and 4) no defect on xenon-ventilation maps. Emphysema index (EI), airway wall thickness (Pi10), and mean ventilation values in the whole lung, peripheral lung, and central lung areas were quantified and compared between the two groups using the Student’s t test. Results: Most patients with ACOS showed the peripheral wedge/diffuse defect (n = 14, 66.7%), whereas patients with COPD commonly showed the diffuse heterogeneous defect and lobar/segmental/subsegmental defect (n = 21, 45.7% and n = 20, 43.5%, respectively). The prevalence of ventilation defect patterns showed significant intergroup differences (p < 0.001). The quantified ventilation values in the peripheral lung areas were significantly lower in patients with ACOS than in patients with COPD (p = 0.045). The quantified Pi10 was significantly higher in patients with ACOS than in patients with COPD (p = 0.041); however, EI was not significantly different between the two groups. Conclusion: The ventilation abnormalities on the visual and quantitative assessments of xenon-ventilation DECT differed between patients with ACOS and patients with COPD. Xenon-ventilation DECT may demonstrate the different physiologic changes of pulmonary ventilation in patients with ACOS and COPD.

Quantitative Vertebral Bone Density Seen on Chest CT in Chronic Obstructive Pulmonary Disease Patients: Association with Mortality in the Korean Obstructive Lung Disease Cohort

Hwang Hye Jeon,이상민,Seo Joon Beom,Kim Ji-Eun,Choi Hye Young,Kim Namkug,Lee Jae Seung,Lee Sei Won,Oh Yeon-Mok 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.7

Objective: Patients with chronic obstructive pulmonary disease (COPD) are known to be at risk of osteoporosis. The purpose of this study was to evaluate the association between thoracic vertebral bone density measured on chest CT (DThorax) and clinical variables, including survival, in patients with COPD. Materials and Methods: A total of 322 patients with COPD were selected from the Korean Obstructive Lung Disease (KOLD) cohort. DThorax was measured by averaging the CT values of three consecutive vertebral bodies at the level of the left main coronary artery with a round region of interest as large as possible within the anterior column of each vertebral body using an in-house software. Associations between DThorax and clinical variables, including survival, pulmonary function test (PFT) results, and CT densitometry, were evaluated. Results: The median follow-up time was 7.3 years (range: 0.1–12.4 years). Fifty-six patients (17.4%) died. DThroax differed significantly between the different Global Initiative for Chronic Obstructive Lung Disease stages. DThroax correlated positively with body mass index (BMI), some PFT results, and the six-minute walk distance, and correlated negatively with the emphysema index (EI) (all p < 0.05). In the univariate Cox analysis, older age (hazard ratio [HR], 3.617; 95% confidence interval [CI], 2.119–6.173, p < 0.001), lower BMI (HR, 3.589; 95% CI, 2.122–6.071, p < 0.001), lower forced expiratory volume in one second (FEV1) (HR, 2.975; 95% CI, 1.682–5.262, p < 0.001), lower diffusing capacity of the lung for carbon monoxide corrected with hemoglobin (DLCO) (HR, 4.595; 95% CI, 2.665–7.924, p < 0.001), higher EI (HR, 3.722; 95% CI, 2.192–6.319, p < 0.001), presence of vertebral fractures (HR, 2.062; 95% CI, 1.154–3.683, p = 0.015), and lower DThorax (HR, 2.773; 95% CI, 1.620–4.746, p < 0.001) were significantly associated with all-cause mortality and lung-related mortality. In the multivariate Cox analysis, lower DThorax (HR, 1.957; 95% CI, 1.075–3.563, p = 0.028) along with older age, lower BMI, lower FEV1, and lower DLCO were independent predictors of all-cause mortality. Conclusion: The thoracic vertebral bone density measured on chest CT demonstrated significant associations with the patients’ mortality and clinical variables of disease severity in the COPD patients included in KOLD cohort.

New Method for Combined Quantitative Assessment of Air-Trapping and Emphysema on Chest Computed Tomography in Chronic Obstructive Pulmonary Disease: Comparison with Parametric Response Mapping

Hwang Hye Jeon,Seo Joon Beom,Lee Sang Min,Kim Namkug,이재연,Lee Jae Seung,Lee Sei Won,Oh Yeon-Mok,Lee Sang-Do 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.10

Objective: Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD. Materials and Methods: A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis. Results: The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FVC) (r = -0.659–0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV1 and FEV1/FVC (R2 = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R2 = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R2 = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM. Conclusion: The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.

Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT

Hwang, Hye Jeon,Seo, Joon Beom,Lee, Jin Seong,Song, Jae-Woo,Kim, Song Soo,Lee, Hyun Joo,Lim, Chae Hun The Korean Society of Radiology 2012 KOREAN JOURNAL OF RADIOLOGY Vol.13 No.6

<P><B>Objective</B></P><P>To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT.</P><P><B>Materials and Methods</B></P><P>Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung.</P><P><B>Results</B></P><P>Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP.</P><P><B>Conclusion</B></P><P>IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.</P>

Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part II: Assessment of Radiologists' Preferences Using Dual Source CT

Hwang, Hye Jeon,Seo, Joon Beom,Lee, Jin Seong,Song, Jae-Woo,Kim, Song Soo,Lee, Hyun Joo,Lim, Chae Hun The Korean Society of Radiology 2012 KOREAN JOURNAL OF RADIOLOGY Vol.13 No.6

<P><B>Objective</B></P><P>To evaluate the impact of radiation dose and reconstruction algorithms on radiologists' preferences, and whether an iterative reconstruction in image space (IRIS) can be used for dose reduction in chest CT.</P><P><B>Materials and Methods</B></P><P>Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying the dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from one tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Ten H-IRIS/F-IRIS, 10 H-FBP/H-IRIS, 40 F-FBP/F-IRIS and 40 F-FBP/H-IRIS pairs of each SDCT and LDCT were randomized. The preference for clinical usage was determined by two radiologists with a 5-point-scale system for the followings: noise, contrast, and sharpness of mediastinum and lung.</P><P><B>Results</B></P><P>Radiologists preferred IRIS over FBP images in the same radiation dose for the evaluation of the lungs in both SDCT (p = 0.035) and LDCT (p < 0.001). When comparing between H-IRIS and F-IRIS, decreased radiation resulted in decreased preference. Observers preferred H-IRIS over F-FBP for the lungs in both SDCT and LDCT, even with reduced radiation dose by half in IRIS image (p < 0.05).</P><P><B>Conclusion</B></P><P>Radiologists' preference may be influenced by both radiation dose and reconstruction algorithm. According to our preliminary results, dose reduction at 50% with IRIS may be feasible for lung parenchymal evaluation.</P>

Right hepatic vein stenosis at anastomosis in patients after living donor liver transplantation: optimal Doppler US venous pulsatility index and CT criteria--receiver operating characteristic analysis.

Hwang, Hye Jeon,Kim, Kyoung Won,Jeong, Woo Kyoung,Song, Gi-Won,Ko, Gi-Young,Sung, Kyu Bo,Shin, Yong Moon,Kim, Pyo Nyun,Ha, Tae-Yong,Moon, Deok-Bog,Kim, Ki-Hun,Ahn, Chul-Soo,Hwang, Shin,Lee, Sung-Gyu Radiological Society of North America 2009 Radiology Vol.253 No.2

<P>PURPOSE: To establish optimal Doppler ultrasonographic (US) venous pulsatility index and computed tomographic (CT) criteria for right hepatic vein (RHV) stenosis after living donor liver transplantation (LDLT) and to compare accuracies of these methods by using receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: This retrospective study was approved by an institutional review board; informed consent was waived. Eighty patients (48 men, 32 women; mean age, 51.5 years +/- 9.2 [standard deviation]) underwent Doppler US and CT within 8 days of hepatic venography following right lobe LDLT between October 2006 and September 2008. At venography, RHVs were classified into a stenosis or nonstenosis group. At Doppler US, venous pulsatility index was defined as the difference between maximum and minimum frequency shifts divided by maximum frequency shift. At CT, diameters of anastomosis and RHV were measured; percentage of stenosis was calculated. Mean Doppler US and CT parameters in the two groups were compared; ROC analysis was performed. RESULTS: There were 30 stenotic and 50 nonstenotic RHVs. Mean venous pulsatility index and mean anastomosis diameter were significantly lower and mean percentage of stenosis was significantly higher in the stenosis than the nonstenosis group (P < .001 each). Optimal cutoffs for venous pulsatility index, anastomosis diameter, and percentage of stenosis were 0.16, 3.7 mm, and 47%, respectively. Sensitivity and specificity were 86.7% and 68.0% for venous pulsatility index, 96.7% and 88.0% for anastomosis diameter, and 96.7% and 86.0% for percentage of stenosis, respectively. At ROC analysis, anastomosis diameter (P = .002) and percentage of stenosis (P = .003) were significantly more accurate than venous pulsatility index. CONCLUSION: CT is more accurate than Doppler US for RHV stenosis after LDLT, with venous pulsatility index as the sole sonographic criterion. Patients suspected of having RHV stenosis at Doppler US may benefit from CT to reduce unnecessary venography.</P>

Hepatic outflow obstruction at middle hepatic vein tributaries or inferior right hepatic veins after living donor liver transplantation with modified right lobe graft: comparison of CT and Doppler ultrasound.

Hwang, Hye Jeon,Kim, Kyoung Won,Jeong, Woo Kyoung,Kim, So Yeon,Song, Gi-Won,Hwang, Shin,Lee, Sung-Gyu American Roentgen Ray Society, etc.] 2009 American Journal of Roentgenology Vol.193 No.3

<P>OBJECTIVE: The objective of our study was to compare CT and Doppler ultrasound in the diagnosis of hepatic outflow obstruction at the middle hepatic vein (MHV) tributaries and inferior right hepatic veins (RHVs) after living donor liver transplantation (LDLT) with modified right lobe grafts. MATERIALS AND METHODS: Thirty-seven venographies were performed in 36 patients after LDLT with modified right lobe grafts, evaluating 51 MHV tributaries and 25 inferior RHVs. They were classified as obstructed or nonobstructed. On Doppler ultrasound or CT, flow patterns of the MHV tributaries and inferior RHVs or the relative parenchymal attenuation, enhancement, and opacification of these veins were evaluated for the diagnosis of hepatic outflow obstruction. McNemar tests were performed to compare the diagnostic values of Doppler ultrasound and CT. RESULTS: On the basis of hepatic venography, 33 MHV tributaries were categorized as obstructed and 18 as nonobstructed, and 16 inferior RHVs were categorized as obstructed and nine as nonobstructed. For the diagnosis of MHV tributary obstruction, Doppler ultrasound was more sensitive and accurate, although less specific, than CT (97% vs 39%, respectively, p < 0.001; 86% vs 61%, p = 0.0209; 67% vs 100%, p = 0.0412). Similarly, Doppler ultrasound was more sensitive (94% vs 31%, respectively) and accurate (84% vs 56%) than CT, although less specific (67% vs 100%), for the diagnosis of inferior RHV obstruction, with a statistical significance only for sensitivity (p = 0.002, 0.092, and 0.248, respectively). CONCLUSION: Doppler ultrasound is more sensitive and accurate than CT for the detection of obstruction at the MHV tributaries and inferior RHVs in patients after LDLT using modified right lobe grafts. Although current CT criteria produce high specificity and may reduce unnecessary invasive venographies, optimal CT criteria with acceptable sensitivity should be reestablished.</P>