• Advances in nano research
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• 제16권4호
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• pp.325-340
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• 2024

There are several novel uses for dispersing many nanoparticles into a conventional fluid, including dynamic sealing, damping, heat dissipation, microfluidics, and more. Therefore, melting heat and mass transfer characteristics of a 3-D MHD Hybrid Nanofluid flow over a rotating disc with presenting dufour and soret effects are assessed numerically in this study. In this instance, we investigated both ferric sulfate and molybdenum disulfide as nanoparticles suspended within base fluid water. The governing partial differential equations are transformed into linked higher-order non-linear ordinary differential equations by the local similarity transformation. The collection of these deduced equations is then resolved using a Chebyshev spectral collocation-based algorithm built into the Mathematica software. To demonstrate how different instances of hybrid/ nanofluid are impacted by changes in temperature, velocity, and the distribution of nanoparticle concentration, examples of graphical and numerical data are given. For many values of the material parameters, the computational findings are shown. Simulations conducted for different physical parameters in the model show that adding hybrid nanoparticle to the fluid mixture increases heat transfer in comparison to simple nanofluids. It has been identified that hybrid nanoparticles, as opposed to single-type nanoparticles, need to be taken into consideration to create an effective thermal system. Furthermore, porosity lowers the velocities of simple and hybrid nanofluids in both cases. Additionally, results show that the drag force from skin friction causes the nanoparticle fluid to travel more slowly than the hybrid nanoparticle fluid. The findings also demonstrate that suction factors like magnetic and porosity parameters, as well as nanoparticles, raise the skin friction coefficient. Furthermore, It indicates that the outcomes from different flow scenarios correlate and are in strong agreement with the findings from the published literature. Bar chart depictions are altered by changes in flow rates. Moreover, the results confirm doctors' views to prescribe hybrid nanoparticle and particle nanoparticle contents for achalasia patients and also those who suffer from esophageal stricture and tumors. The results of this study can also be applied to the energy generated by the melting disc surface, which has a variety of industrial uses. These include, but are not limited to, the preparation of semiconductor materials, the solidification of magma, the melting of permafrost, and the refreezing of frozen land.

• Korean Journal of Radiology
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• 제22권11호
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• pp.1777-1785
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• 2021

Objective: To investigate the accuracy of the Agatston score obtained with the ultra-high-pitch (UHP) acquisition mode using tin-filter spectral shaping (Sn150 kVp) and a kVp-independent reconstruction algorithm to reduce the radiation dose. Materials and Methods: This prospective study included 114 patients (mean ± standard deviation, 60.3 ± 9.8 years; 74 male) who underwent a standard 120 kVp scan and an additional UHP Sn150 kVp scan for coronary artery calcification scoring (CACS). These two datasets were reconstructed using a standard reconstruction algorithm (120 kVp + Qr36d, protocol A; Sn150 kVp + Qr36d, protocol B). In addition, the Sn150 kVp dataset was reconstructed using a kVp-independent reconstruction algorithm (Sn150 kVp + Sa36d, protocol C). The Agatston scores for protocols A and B, as well as protocols A and C, were compared. The agreement between the scores was assessed using the intraclass correlation coefficient (ICC) and the Bland-Altman plot. The radiation doses for the 120 kVp and UHP Sn150 kVp acquisition modes were also compared. Results: No significant difference was observed in the Agatston score for protocols A (median, 63.05; interquartile range [IQR], 0-232.28) and C (median, 60.25; IQR, 0-195.20) (p = 0.060). The mean difference in the Agatston score for protocols A and C was relatively small (-7.82) and with the limits of agreement from -65.20 to 49.56 (ICC = 0.997). The Agatston score for protocol B (median, 34.85; IQR, 0-120.73) was significantly underestimated compared with that for protocol A (p < 0.001). The UHP Sn150 kVp mode facilitated an effective radiation dose reduction by approximately 30% (0.58 vs. 0.82 mSv, p < 0.001) from that associated with the standard 120 kVp mode. Conclusion: The Agatston scores for CACS with the UHP Sn150 kVp mode with a kVp-independent reconstruction algorithm and the standard 120 kVp demonstrated excellent agreement with a small mean difference and narrow agreement limits. The UHP Sn150 kVp mode allowed a significant reduction in the radiation dose.

• Korean Journal of Radiology
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• 제22권6호
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• pp.959-969
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• 2021

Objective: This study aimed to evaluate the role of preoperative two-dimensional (2D) shear wave elastography (SWE) in assessing the stages of liver fibrosis in patients with suspected biliary atresia (BA) and compared its diagnostic performance with those of serum fibrosis biomarkers. Materials and Methods: This study was approved by the ethical committee, and written informed parental consent was obtained. Two hundred and sixteen patients were prospectively enrolled between January 2012 and October 2018. The 2D SWE measurements of 69 patients have been previously reported. 2D SWE measurements, serum fibrosis biomarkers, including fibrotic markers and biochemical test results, and liver histology parameters were obtained. 2D SWE values, serum biomarkers including, aspartate aminotransferase to platelet ratio index (APRi), and other serum fibrotic markers were correlated with the stages of liver fibrosis by METAVIR. Receiver operating characteristic (ROC) curves and area under the ROC (AUROC) curve analyses were used. Results: The correlation coefficient of 2D SWE value in correlation with the stages of liver fibrosis was 0.789 (p < 0.001). The cut-off values of 2D SWE were calculated as 9.1 kPa for F1, 11.6 kPa for F2, 13.0 kPa for F3, and 15.7 kPa for F4. The AUROCs of 2D SWE in the determination of the stages of liver fibrosis ranged from 0.869 to 0.941. The sensitivity and negative predictive value of 2D SWE in the diagnosis of ≥ F3 was 93.4% and 96.0%, respectively. The diagnostic performance of 2D SWE was superior to that of APRi and other serum fibrotic markers in predicting severe fibrosis and cirrhosis (all p < 0.005) and other serum biomarkers. Multivariate analysis showed that the 2D SWE value was the only statistically significant parameter for predicting liver fibrosis. Conclusion: 2D SWE is a more effective non-invasive tool for predicting the stage of liver fibrosis in patients with suspected BA, compared with serum fibrosis biomarkers.

• Korean Journal of Radiology
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• 제22권8호
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• pp.1266-1278
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• 2021

Objective: We aimed to compare the aortic valve area (AVA) calculated using fast high-resolution three-dimensional (3D) magnetic resonance (MR) image acquisition with that of the conventional two-dimensional (2D) cine MR technique. Materials and Methods: We included 139 consecutive patients (mean age ± standard deviation [SD], 68.5 ± 9.4 years) with aortic valvular stenosis (AS) and 21 asymptomatic controls (52.3 ± 14.2 years). High-resolution T2-prepared 3D steady-state free precession (SSFP) images (2.0 mm slice thickness, 10 contiguous slices) for 3D planimetry (3DP) were acquired with a single breath hold during mid-systole. 2D SSFP cine MR images (6.0 mm slice thickness) for 2D planimetry (2DP) were also obtained at three aortic valve levels. The calculations for the effective AVA based on the MR images were compared with the transthoracic echocardiographic (TTE) measurements using the continuity equation. Results: The mean AVA ± SD derived by 3DP, 2DP, and TTE in the AS group were 0.81 ± 0.26 cm², 0.82 ± 0.34 cm², and 0.80 ± 0.26 cm², respectively (p = 0.366). The intra-observer agreement was higher for 3DP than 2DP in one observer: intraclass correlation coefficient (ICC) of 0.95 (95% confidence interval [CI], 0.94-0.97) and 0.87 (95% CI, 0.82-0.91), respectively, for observer 1 and 0.97 (95% CI, 0.96-0.98) and 0.98 (95% CI, 0.97-0.99), respectively, for observer 2. Inter-observer agreement was similar between 3DP and 2DP, with the ICC of 0.92 (95% CI, 0.89-0.94) and 0.91 (95% CI, 0.88-0.93), respectively. 3DP-derived AVA showed a slightly higher agreement with AVA measured by TTE than the 2DP-derived AVA, with the ICC of 0.87 (95% CI, 0.82-0.91) vs. 0.85 (95% CI, 0.79-0.89). Conclusion: High-resolution 3D MR image acquisition, with single-breath-hold SSFP sequences, gave AVA measurement with low observer variability that correlated highly with those obtained by TTE.

• 한국조경학회지
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• 제52권2호
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• pp.96-109
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• 2024

본 연구는 딥러닝 모델 중 VGG-16 및 ResNet50 모델을 활용하여 전시 정원의 유사성 평가 방법을 제시하는 것에 목적이 있다. VGG-16과 ResNet50 모델을 기반으로 전시 정원 유사성 판단을 위한 모형을 개발하였고, 이를 DRG(deep recognition of similarity in show garden design)모형이라 한다. 평가를 위한 방법으로 GAP와 피어슨 상관계수를 활용한 알고리즘을 사용하여 모형을 구축하고 1순위(Top1), 3순위(Top3), 5순위(Top5)에서 원본 이미지와 유사한 이미지를 도출하는 총 개수 비교로 유사성의 정확도를 분석하였다. DRG 모형에 활용된 이미지 데이터는 국외 쇼몽가든페스티벌 전시 정원 총 278개 작품과 국내 정원박람회인 서울정원박람회 27개 작품 및 코리아가든쇼 전시정원 이미지 17개 작품이다. DRG모형을 활용하여 동일 집단과 타 집단간의 이미지 분석을 진행하였고, 이를 기반으로 전시 정원 유사성의 가이드라인을 제시하였다. 첫째, 전체 이미지 유사성 분석은 ResNet50 모델을 기반으로 하여 데이터 증강 기법을 적용하는 것이 유사성 도출에 적합하였다. 둘째, 내부 구조와 외곽형태에 중점을 둔 이미지 분석에서는 형태에 집중하기 위한 일정한 크기의 필터(16cm × 16cm)를 적용하여 이미지를 생성하고 VGG-16 모델을 적용하여 유사성을 비교하는 방법이 효과적임을 알 수 있었다. 이때, 이미지 크기는 448 × 448 픽셀이 효과적이며, 유채색의 원본 이미지를 기본으로 설정함을 제안하였다. 이러한 연구 결과를 토대로 전시 정원 유사성 판단에 대한 정량적 방법을 제안하고, 향후 다양한 분야와의 융합 연구를 통해 정원 문화의 지속적인 발전에 기여할 것으로 기대한다.

• 대한치위생과학회지
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• 제6권2호
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• pp.101-114
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• 2023

연구배경: 본 연구는 치면열구전색(치아홈메우기)에 대한 전반적인 인식을 살펴봄으로써 현재 정체되어 있는 치면열구전색의 활성화를 위한 방안을 제시하고자 수행되었다. 연구방법: 치면열구전색 보장성 정책의 변화에 따른 사회적 인식을 확인하고자 5개 차수로 시기를 분류하였다. 1차시기(2009.12.1.~2010.11.30.), 2차시기(2010.12.1.~2012.9.30.), 3차시기(2012.10.1.~2013.5.5.), 4차시기(2013.5.6.~2017.9.30.), 5차시기(2017.10.1.~2022.12.31.)로 각각 설정하였다. 비정형 빅데이터 분석방법인 텍스트마이닝 분석방법을 활용하였다. 텍스톰을 사용하여 키워드를 수집 및 분석하였으며, 상위 키워드 30개의 빈도수, 의미 연결망의 구조적 특징, 중심성 분석, QAP 상관분석 및 동시출현 단어분석을 실시하였다. 연구결과: 빈도분석 결과 시기별로 상위권에 속한 키워드는 '충치', '치료', '어린이' 등이 공통적으로 나타났다. 치면열구전색의 시기별 의미연결망 구조적 특징에서 밀도지수는 모든 시기별 약 1.00으로 확인되었다. QAP 상관분석결과 1차시기와 2차시기, 4차시기와 5차시기의 상관계수가 0.834로 가장 높은 상관을 보였다. 동시출현 단어분석결과 모든 시기에 걸쳐 '충치'와 '예방'이 1위로 나타났다. 결론: 본 연구를 통해 치면열구전색은 충치예방을 위한 술식과 예방치료로써 사회적 인식이 잘 형성되었음을 알 수 있었다. 그러나 보건교육에 대한 인식은 낮았다. 정체된 치면열구전색을 활성화하기 위해서는 효과적인 교육을 강화해 나가야 하는 노력이 필요하겠다.

• 한국응용곤충학회지
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• 제63권1호
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• pp.53-61
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• 2024

살충제 저항성 목화진딧물 집단(완주, 춘천, 고성)에 대한 3종(afidopyropen, chlorfenapyr, cyantraniliprole) 약제별 감수성과 혼용에 따른 방제효과를 평가하였다. 3개 야외집단에 대해서 3약제 모두100배 이상의 저항성비를 보였다. 혼합제의 협력작용을 평가하기 위해 반수치사농도(LC₅₀)을 이용한 조합지수(CI), %M_(synergism), 연합독성계수(CTC), 와들리 비율(WR), 상승비율(SR)와 사충률을 이용한 아보트 비율(AR)로 비교하였다. Afidopyropen + chlorfenapyr은 모든 야외집단에 대해서 살충활성의 증가를 보였고, chlorfenapyr + cyantraniliprole, afidopyropen + cayntraniliprole은 완주, 춘천 집단에 대해서 살충활성의 증가를 보였다. 그러나 chlorfenapyr + cyantraniliprole (CI, 1.63; %M_(synergism), 30; CTC, 64.0; WR, 0.6, AR, 0.54)과 afidopyropen + cyantraniliprole (CI, 6.7; %M_(synergism), 1; CTC, 19.8; WR, 0.2, AR ≤ 0.55)은 고성 집단에서 길항작용을 나타내었다. 포장조건에서도 afidopyropen + chlorfenapyr, chlorfenapyr + cyantraniliprole, afidopyropen + cyantraniliprole은 99% 이상의 높은 방제가를 보여 향후 살충제 저항성 목화진딧물 방제용 혼합제 개발에 유용하게 활용될 것이다.

• 문화기술의 융합
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• 제10권3호
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• pp.683-692
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• 2024

본 연구는 간호대학생의 통합시뮬레이션 실습 교육이 의사소통능력, 학습자신감, 임상추론역량, 임상수행능력에 미치는 효과를 파악하고자 시도된 단일군 사전·사후 유사실험연구이다. 연구대상은 G광역시에 소재한 일개 대학의 4학년 간호대학생 41명으로 2023년 9월부터 11월까지 9주간 운영되었다. 수집된 자료는 SPSS 23.0을 이용하여 기술통계, paired t-test, Pearson's correlation coefficient로 분석하였으며 연구결과는 다음과 같다. 첫째, 시뮬레이션 실습 교육 후 학습자신감(t=-2.21, p=.033), 임상추론역량(t=-2.97, p=.005), 임상수행능력(t=-2.84, p=.007)은 유의미한 효과가 있는 것으로 나타났으나 의사소통능력은 유의미한 차이를 나타내지 않았다(t=-.224, p=.824). 둘째, 간호대학생의 시뮬레이션 수업 후 임상수행능력은 의사소통능력(r=.650, p<.001), 학습자신감(r=.440, p<.001), 임상추론역량(r=.824, p<.001)와 정적 상관관계가 있는 것으로 나타났다. 본 연구결과를 바탕으로 간호대학생의 통합시뮬레이션 실습 교육은 간호대학생의 학습자신감과 임상추론역량, 임상수행능력 향상에 효과적인 교육방법이며 간호대학생의 임상수행능력을 높이기 위해서는 다양한 시나리오를 통한 시뮬레이션 실습 운영이 필요하다.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2182-2189
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• 2024

The high-purity germanium gamma-ray spectrometer was used to measure the radioisotope in surface water of lakes in a Chinee petroleum industrial area. 92 samples were collected from surface water of three lakes. Activity concentrations of ²³²Th, ²²⁶Ra and ⁴⁰K in three lakes were measured, distributed in the range of 101.8-209.4, 192.1-224.9 and 335.0-548.9 mBq/L, respectively. Results were all within the limits of WHO and China. Potential environmental and health risks were assessed by calculating some radiation hazard indicators, radium equivalent index, annual effective dose, excess lifetime cancer risk, absorbed dose rate, external hazard index, internal hazard index, annual gonadal dose equivalent, activity utilization index and representative gamma index, which ranged 0.38-0.54 Bq/L, 0.06-0.08 mSv/y, 0.23 × 10^-3-0.31 × 10^-3, 0.17-0.24 nGy/h, 1.01 × 10^-3-1.46 × 10^-3, 1.55 × 10^-3-2.02 × 10^-3, 1.16-1.66 μSv/y, 3.13 × 10^-3-4.45 × 10^-3 and 2.60 × 10^-3-3.77 × 10^-3. The results were all at acceptable levels, meaning no impact on human health. The relationship between the electrical conductivity of surface water and the activity concentration of ²³²Th, ²²⁶Ra and ⁴⁰K was evaluated. The electrical conductivity value was 0.241-0.369 mS/cm, showing a significant correlation coefficient between ²²⁶Ra and ⁴⁰K and electrical conductivity. Multivariate statistical methods were used to determine the relationship between the activity concentrations of ²³²Th, ²²⁶Ra, and ⁴⁰K, radiation hazard indicators and electrical conductivity.

• Korean Journal of Radiology
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• 제25권7호
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• pp.634-643
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• 2024

Objective: This study aimed to evaluate the diagnostic efficacy and safety of low-contrast-dose, dual-source dual-energy CT before transcatheter aortic valve replacement (TAVR) in patients with compromised renal function. Materials and Methods: A total of 54 consecutive patients (female:male, 26:38; 81.9 ± 7.3 years) with reduced renal function underwent pre-TAVR dual-energy CT with a 30-mL contrast agent between June 2022 and March 2023. Monochromatic (40- and 50-keV) and conventional (120-kVp) images were reconstructed and analyzed. The subjective quality score, vascular attenuation, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared among the imaging techniques using the Friedman test and post-hoc analysis. Interobserver reliability for aortic annular measurement was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The procedural outcomes and incidence of post-contrast acute kidney injury (AKI) were assessed. Results: Monochromatic images achieved diagnostic quality in all patients. The 50-keV images achieved superior vascular attenuation and CNR (P < 0.001 in all) while maintaining a similar SNR compared to conventional CT. For aortic annular measurement, the 50-keV images showed higher interobserver reliability compared to conventional CT: ICC, 0.98 vs. 0.90 for area and 0.97 vs. 0.95 for perimeter; 95% limits of agreement width, 0.63 cm² vs. 0.92 cm² for area and 5.78 mm vs. 8.50 mm for perimeter. The size of the implanted device matched CT-measured values in all patients, achieving a procedural success rate of 92.6%. No patient experienced a serum creatinine increase of ≥ 1.5 times baseline in the 48-72 hours following CT. However, one patient had a procedural delay due to gradual renal function deterioration. Conclusion: Low-contrast-dose imaging with 50-keV reconstruction enables precise pre-TAVR evaluation with improved image quality and minimal risk of post-contrast AKI. This approach may be an effective and safe option for pre-TAVR evaluation in patients with compromised renal function.