• 한국컴퓨터정보학회논문지
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• 제14권12호
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• pp.97-107
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• 2009

TV뉴스는 매일 전 세계의 소식을 불특정 다수에게 전달함으로써 시청자의 정보 해석에 중요한 영향을 미친다. 방송환경의 급격한 변화로 HDTV로 불리는 고화질 시대에 앵커의 미세한 표정과 옷차림까지 들춰질 수 있는 시각적인 집중도가 있는 점을 감안할 때, 해상도에 더욱 신경을 써야하는 세심함이 요구된다. 따라서 HDTV에 더욱 중요한 조명 기술이 가지는 표현의 미는 강조의 여지가 없다. 보도방송에서도 이러한 변화추세에 따른 현상으로, TV 뉴스 제작 행태는 DLP(Digital Lighting Processing)나 LED(Light Emitting Diode)기법을 통해서, 기존 TV뉴스 제작 행태를 탈피하고자 하는 변화의 길을 모색해 왔다. 이와 같은 노력은 HDTV에 적합한 화질을 구현하는데 기여하였다. 요즈음 디지털영상에서는 조명 장치만을 사용하던 기존 아날로그 기반의 조명 환경이 IT기술의 발전과 더불어 디지털화된 조명 장비의 개발로 TV뉴스 제작행태에 활력을 불어 넣고 있다. 이러한 변화는 HDTV 스튜디오 구축과 세트 및 조명 시스템을 설비하기에 이르렀다 1990년대 이후, HDTV의 등장으로 필름 세트와 스크린에 영상을 투사하는 프로젝터와 최근 들어 그 활용도가 커진 PDP, LCD, DLP등이 있으며, 뉴스 외에 다른 프로그램에서 자주사용되는 LED 배경화면이 그 예이다. 본 논문은 이러한 방송환경 변화에 따라 텔레비전 영상 구성 요소가 TV뉴스 시청자의 화면 집중도에 미치는 영향을 탐색하기 위해서 KBS9시 뉴스의 조명 기법을 분석하였다. 분석 결과를 토대로 앵커가 정보를 전달하는데 있어서 앵커 이미지 형성의 범주를 조명 기법으로 제안한다.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권6호
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• pp.897-906
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• 2017

프로젝션 맵핑(공간증강현실)은 현실세계에서 다양한 가상의 환영(幻影)을 만들어내는 것으로 최근에 많은 분야에 사용되고 있다. 기존의 프로젝션 맵핑에서는 사용자와의 자연스러운 상호작용으로서 접히거나 구부러지는 것 과 같은 유연한 물체의 기하학적인 변형 속성(예: 용지)의 움직임을 고려하지 않았다. 또한, 정적 물체에 대한 프로젝션 맵핑에 대한 많은 연구가 있었지만, 유연한 타깃의 움직임을 추적하고 사용자와의 상호작용 측면에서 모양이 변형된 물체에 맵핑을 정확히 하는 다이내믹 프로젝션 맵핑은 여전히 도전해야할 연구 분야이다. 따라서 본 논문에서는 Unity3D와 ARToolkit을 이용한 실험을 통해 단단하지 않은 물체에 대한 견실한 추적과 정확한 맵핑 방법을 제안한다. 제안하는 방법은 큐빅 베지어 곡면 형성, 움직임 변형 값 렌더링 과정, 멀티플 마커 인식과 트래킹 과정, 실시간 웹캠 지속 촬영의 4가지 실험 단계로 구성된다. 사용자는 물체에 변형을 주기 위해 직접 접고, 휘고, 구부리고 비틀 수 있다. 제안 방법은 세 가지 긍정적인 결과를 도출할 수 있다. 첫째, 물체의 형태가 강하게 변형되어 있어도 감지 가능하다. 둘째, 사용자가 직접 물체에 변형을 주는 과정에서 물체의 일부분을 차단하고 있을 때의 Occlusion오류를 줄일 수 있어 정확한 트래킹을 할 수 있다. 셋째, 제안 방법의 견실하고 정확함은 빠른 속도로 물체의 움직임을 감지하게 하므로 실시간으로 결과 값을 물체에 투영할 수 있다.

• 자원환경지질
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• 제56권6호
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• pp.817-830
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• 2023

This study investigates the age of the surficial rocks in the Arunta region using Uranium-Lead (U-Pb) geochronological dating. Rock samples were collected at four locations, Cattle-Water Pass (CP 1610), Gough Dam (GD 1622 and GD 1610), and London-Eye (LE 1601), within the Strangways Metamorphic Complex and crushed by selFragging. Subsequently, the zircon grains were imaged using Cathodoluminescence (CL) analysis and the U-Pb (uranium and lead) isotope ratios and the chrono-stratigraphy were measured. The imaged zircon revealed an anomalous heterogeneous crystal structure. Ellipses of the samples at locations GD1601, CP1610, and GD1622 fall below the intercept indicating the ages produced discordant patterns, whereas LE1601 intersects the Concordia curve at two points, implying the occurrence of an event of significant impact. For the rock sample at CP1610, the estimated mean age is 1742.2 ± 9.2 Ma with mean squared weighted deviation (MSWD) = 0.49 and probability of equivalence of 0.90; 1748 ± 15 Ma - MSWD = 1.02 and probability of equivalence of 0.40 for GD1622; and 1784.4 ± 9.1 Ma with MSWD of 1.09 and probability of equivalence of 0.37 for LE1601. But for samples at GD1601, two different age groups with different means occurred: 1) below the global mean (1792.2 ± 32 Ma) estimated at 1738.2 ± 14 Ma with MSWD of 0.109 and probability of equivalence of 0.95 and 2) above it with mean of 1838.22 ± 14 Ma, MSWD of 1.6 and probability of equivalence of 0.95. Analysis of the zircon grains has shown a discrepancy in the age range between 1700 Ma and 1800 Ma compared to the ASO dated to have occurred between 440 and 300 Ma. Moreover, apparent similarity in age of the core and rim means that the mineral crystallized relatively quickly without significant interruptions and effect on the isotopic system. This may have constraint the timing and extent of geological events that might have affected the mineral, such as metamorphism or hydrothermal alteration.

• Korean Journal of Radiology
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• 제21권4호
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• pp.431-441
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• 2020

Objective: To compare the diagnostic performance and interobserver variability of strain ratio obtained from one or two regions of interest (ROI) on breast elastography. Materials and Methods: From April to May 2016, 140 breast masses in 140 patients who underwent conventional ultrasonography (US) with strain elastography followed by US-guided biopsy were evaluated. Three experienced breast radiologists reviewed recorded US and elastography images, measured strain ratios, and categorized them according to the American College of Radiology breast imaging reporting and data system lexicon. Strain ratio was obtained using the 1-ROI method (one ROI drawn on the target mass), and the 2-ROI method (one ROI in the target mass and another in reference fat tissue). The diagnostic performance of the three radiologists among datasets and optimal cut-off values for strain ratios were evaluated. Interobserver variability of strain ratio for each ROI method was assessed using intraclass correlation coefficient values, Bland-Altman plots, and coefficients of variation. Results: Compared to US alone, US combined with the strain ratio measured using either ROI method significantly improved specificity, positive predictive value, accuracy, and area under the receiver operating characteristic curve (AUC) (all p values < 0.05). Strain ratio obtained using the 1-ROI method showed higher interobserver agreement between the three radiologists without a significant difference in AUC for differentiating breast cancer when the optimal strain ratio cut-off value was used, compared with the 2-ROI method (AUC: 0.788 vs. 0.783, 0.693 vs. 0.715, and 0.691 vs. 0.686, respectively, all p values > 0.05). Conclusion: Strain ratios obtained using the 1-ROI method showed higher interobserver agreement without a significant difference in AUC, compared to those obtained using the 2-ROI method. Considering that the 1-ROI method can reduce performers' efforts, it could have an important role in improving the diagnostic performance of breast US by enabling consistent management of breast lesions.

• Korean Journal of Radiology
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• 제22권8호
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• pp.1240-1252
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• 2021

Objective: To compare the accuracy for detecting breast cancer in the diagnostic setting between the use of digital breast tomosynthesis (DBT), defined as DBT alone or combined DBT and digital mammography (DM), and the use of DM alone through a systematic review and meta-analysis. Materials and Methods: Ovid-MEDLINE, Ovid-Embase, Cochrane Library and five Korean local databases were searched for articles published until March 25, 2020. We selected studies that reported diagnostic accuracy in women who were recalled after screening or symptomatic. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. A bivariate random effects model was used to estimate pooled sensitivity and specificity. We compared the diagnostic accuracy between DBT and DM alone using meta-regression and subgroup analyses by modality of intervention, country, existence of calcifications, breast density, Breast Imaging Reporting and Data System category threshold, study design, protocol for participant sampling, sample size, reason for diagnostic examination, and number of readers who interpreted the studies. Results: Twenty studies (n = 44513) that compared DBT and DM alone were included. The pooled sensitivity and specificity were 0.90 (95% confidence interval [CI] 0.86-0.93) and 0.90 (95% CI 0.84-0.94), respectively, for DBT, which were higher than 0.76 (95% CI 0.68-0.83) and 0.83 (95% CI 0.73-0.89), respectively, for DM alone (p < 0.001). The area under the summary receiver operating characteristics curve was 0.95 (95% CI 0.93-0.97) for DBT and 0.86 (95% CI 0.82-0.88) for DM alone. The higher sensitivity and specificity of DBT than DM alone were consistently noted in most subgroup and meta-regression analyses. Conclusion: Use of DBT was more accurate than DM alone for the diagnosis of breast cancer. Women with clinical symptoms or abnormal screening findings could be more effectively evaluated for breast cancer using DBT, which has a superior diagnostic performance compared to DM alone.

• 한국터널지하공간학회 논문집
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• 제25권6호
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• pp.555-567
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• 2023

현재 지하시설물의 균열을 영상 취득 시스템으로 취득한 경우 점검자가 취득된 영상에서 육안검사를 수행하여 미세균열을 판단한다. 점검자에 의존한 노동집약적인 방법은 점검자의 주관적인 판단에 영향을 받는 문제점을 가지고 있다. 최근에는 딥러닝을 활용하여 자동으로 콘크리트 균열을 탐지하기 위한 연구가 활발하게 수행되고 있다. 대부분의 연구에서는 공개 데이터셋을 활용하거나 분석과정의 객관성이 충분하지 못해 실제 업무에 적용하기 어려운 점이 있다. 본 연구는 실제 검사 시스템과 동일한 형태의 영상을 시험 데이터셋으로 선정하여 딥러닝 모델들을 평가하였다. 균열 탐지의 정확도를 향상시키기 위하여 딥러닝 모델들의 장단점을 상호 보완할 수 있는 앙상블 기법을 적용하였다. 시험 영상에서 폭 0.2 mm, 0.3 mm 및 0.5 mm의 균열들은 각각 80%, 88% 및 89%의 높은 재현율로 탐지되었다. 딥러닝을 적용한 균열 탐지 결과에서는 점검자의 육안 검수 과정에 찾지 못한 다수의 균열들을 포함하고 있었다. 향후 본 연구에서 사용하지 않은 다른 터널의 영상을 시험 영상으로 선정하여 보다 더 객관적인 평가에서 충분한 정확도로 균열을 탐지하게 된다면, 시설물 안점 점검 방식에 딥러닝의 도입이 가능할 것으로 판단된다.

• 대한영상의학회지
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• 제83권1호
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• pp.54-69
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• 2022

심장 돌연사 환자들은 종종 흉통 또는 운동성 호흡곤란 등의 전조증상이 나타나지 않기 때문에 잠재적인 무증상 관상동맥 질환을 조기에 발견하는 것이 매우 중요하다. 관상동맥 전산화단층촬영 혈관조영술은 방사선 노출로 인한 위험성 때문에 무증상 환자에서 스크리닝 검사로 정당화되지 못했었지만 최근에 전산화단층촬영 기술의 비약적인 발전으로 방사선량을 1 mSv 미만으로 최소화함으로써 무증상 환자의 관상동맥 질환 선별 검사의 유용성에 대한 많은 연구가 진행되어 왔다. 그러나, 여전히 무증상 정상인 또는 환자의 관상동맥 질환 선별 검사에 대한 관상동맥 전산화단층촬영 혈관조영술의 유용성에 대해서는 다양한 의견들이 있다. 이 종설에서는 무증상 정상인 또는 환자들에게 관상동맥 질환 선별 검사로 관상동맥 칼슘 점수와 관상동맥 전산화단층촬영 혈관조영술 유용성에 대해서 다양한 문헌고찰을 통해서 알아보았다. 관상동맥 전산화단층촬영 혈관조영술상 무증상 정상인의 2.6%에서 70% 이상의 유의한 관상동맥 협착이 발견되었고, 선별 목적의 관상동맥 전산화단층촬영 혈관조영술이 무증상 건강한 사람의 미래의 심혈관 질환 발생을 예측할 수 있다. 그러나 현재 미국국립보건원에서 진행하고 있는 SCOT-HEART 2 연구가 끝나면 관상동맥 전산화단층촬영 혈관조영술이 무증상 성인의 심혈관 예방에 선별 검사로 적절한지 결정을 내릴 수 있을 것으로 생각된다.

• Korean Journal of Radiology
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• 제25권2호
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• pp.146-156
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• 2024

Objective: Automated breast ultrasound (ABUS) is a relevant imaging technique for early breast cancer diagnosis and is increasingly being used as a supplementary tool for mammography. This study compared the performance of ABUS and handheld ultrasound (HHUS) in detecting and characterizing the axillary lymph nodes (LNs) in patients with breast cancer. Materials and Methods: We retrospectively reviewed the medical records of women with recently diagnosed early breast cancer (≤ T2) who underwent both ABUS and HHUS examinations for axilla (September 2017-May 2018). ABUS and HHUS findings were compared using pathological outcomes as reference standards. Diagnostic performance in predicting any axillary LN metastasis and heavy nodal-burden metastases (i.e., ≥ 3 LNs) was evaluated. The ABUS-HHUS agreement for visibility and US findings was calculated. Results: The study included 377 women (53.1 ± 11.1 years). Among 385 breast cancers in 377 patients, 101 had axillary LN metastases and 30 had heavy nodal burden metastases. ABUS identified benign-looking or suspicious axillary LNs (average, 1.4 ± 0.8) in 246 axillae (63.9%, 246/385). According to the per-breast analysis, the sensitivity, specificity, positive and negative predictive values, and accuracy of ABUS in predicting axillary LN metastases were 43.6% (44/101), 95.1% (270/284), 75.9% (44/58), 82.6% (270/327), and 81.6% (314/385), respectively. The corresponding results for HHUS were 41.6% (42/101), 95.1% (270/284), 75.0% (42/56), 82.1% (270/329), and 81.0% (312/385), respectively, which were not significantly different from those of ABUS (P ≥ 0.53). The performance results for heavy nodal-burden metastases were 70.0% (21/30), 89.6% (318/355), 36.2% (21/58), 97.3% (318/327), and 88.1% (339/385), respectively, for ABUS and 66.7% (20/30), 89.9% (319/355), 35.7% (20/56), 97.0% (319/329), and 88.1% (339/385), respectively, for HHUS, also not showing significant difference (P ≥ 0.57). The ABUS-HHUS agreement was 95.9% (236/246; Cohen's kappa = 0.883). Conclusion: Although ABUS showed limited sensitivity in diagnosing axillary LN metastasis in early breast cancer, it was still useful as the performance was comparable to that of HHUS.

• Korean Journal of Radiology
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• 제24권3호
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• pp.190-203
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• 2023

Objective: We aimed to assess and validate the radiologic and clinical factors that were associated with recurrence and survival after curative surgery for heterogeneous targetoid primary liver malignancies in patients with chronic liver disease and to develop scoring systems for risk stratification. Materials and Methods: This multicenter retrospective study included 197 consecutive patients with chronic liver disease who had a single targetoid primary liver malignancy (142 hepatocellular carcinomas, 37 cholangiocarcinomas, 17 combined hepatocellular carcinoma-cholangiocarcinomas, and one neuroendocrine carcinoma) identified on preoperative gadoxetic acid-enhanced MRI and subsequently surgically removed between 2010 and 2017. Of these, 120 patients constituted the development cohort, and 77 patients from separate institution served as an external validation cohort. Factors associated with recurrence-free survival (RFS) and overall survival (OS) were identified using a Cox proportional hazards analysis, and risk scores were developed. The discriminatory power of the risk scores in the external validation cohort was evaluated using the Harrell C-index. The Kaplan-Meier curves were used to estimate RFS and OS for the different risk-score groups. Results: In RFS model 1, which eliminated features exclusively accessible on the hepatobiliary phase (HBP), tumor size of 2-5 cm or > 5 cm, and thin-rim arterial phase hyperenhancement (APHE) were included. In RFS model 2, tumors with a size of > 5 cm, tumor in vein (TIV), and HBP hypointense nodules without APHE were included. The OS model included a tumor size of > 5 cm, thin-rim APHE, TIV, and tumor vascular involvement other than TIV. The risk scores of the models showed good discriminatory performance in the external validation set (C-index, 0.62-0.76). The scoring system categorized the patients into three risk groups: favorable, intermediate, and poor, each with a distinct survival outcome (all log-rank p < 0.05). Conclusion: Risk scores based on rim arterial enhancement pattern, tumor size, HBP findings, and radiologic vascular invasion status may help predict postoperative RFS and OS in patients with targetoid primary liver malignancies.

• Korean Journal of Radiology
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• 제23권11호
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• pp.1102-1111
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• 2022

Objective: To evaluate the ultrasonography (US) features for diagnosing metastasis in cervical lymph nodes (LNs) in patients with thyroid cancer and compare the US classification of risk of LN metastasis between European and Korean guidelines. Materials and Methods: From January 2014 to December 2018, US-guided fine-needle aspiration was performed on 836 LNs from 714 patients for the preoperative nodal staging of thyroid cancer. The US features of LNs were retrospectively reviewed for the following features: size, presence of hilum, margin, orientation, cystic change, punctate echogenic foci (PEF), large echogenic foci, eccentric cortical thickening, abnormal vascularity, and cortical hyperechogenicity. A multiple logistic regression analysis was performed to identify the independent US features for the diagnosis of metastatic LNs. The diagnostic performance of independent US features was subsequently evaluated. LNs were categorized according to the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and European Thyroid Association (ETA) guidelines, and the correlation between the two sets of classifications was assessed. Results: Absence of the hilum, presence of cystic changes, PEF, abnormal vascularity, and cortical hyperechogenicity were independent US features of metastatic LNs. Cystic changes, PEF, abnormal vascularity, and cortical hyperechogenicity showed high specificity (86.8%-99.6%). The absence of the hilum had the highest sensitivity yet low specificity (66.4%). When LNs were classified according to the ETA guidelines and K-TIRADS, they yielded similar categorizations of malignancy risks and were strongly correlated (Spearman coefficient, 0.9766 [95% confidence interval, 0.973-0.979]). According to the ETA guidelines, 9.8% (82/836) of LNs were classified as "not specified." Conclusion: Absence of hilum, cystic changes, PEF, abnormal vascularity, and cortical hyperechogenicity were independent US features suggestive of metastatic LNs in thyroid cancer. Both K-TIRADS and the ETA guidelines provided similar risk stratification for metastatic LNs with a high correlation; however, the ETA guidelines failed to classify 9.8% of LNs into a specific risk stratum. These results may provide a basis for revising LN classification in future guidelines.