Improvement in Image Quality and Visibility of Coronary Arteries, Stents, and Valve Structures on CT Angiography by Deep Learning Reconstruction

Otgonbaatar Chuluunbaatar,Ryu Jae-Kyun,Shin Jaemin,Woo Ji Young,Seo Jung Wook,Shim Hackjoon,Hwang Dae Hyun 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.11

Objective: This study aimed to investigate whether a deep learning reconstruction (DLR) method improves the image quality, stent evaluation, and visibility of the valve apparatus in coronary computed tomography angiography (CCTA) when compared with filtered back projection (FBP) and hybrid iterative reconstruction (IR) methods. Materials and Methods: CCTA images of 51 patients (mean age ± standard deviation [SD], 63.9 ± 9.8 years, 36 male) who underwent examination at a single institution were reconstructed using DLR, FBP, and hybrid IR methods and reviewed. CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and stent evaluation, including 10%– 90% edge rise slope (ERS) and 10%–90% edge rise distance (ERD), were measured. Quantitative data are summarized as the mean ± SD. The subjective visual scores (1 for worst -5 for best) of the images were obtained for the following: overall image quality, image noise, and appearance of stent, vessel, and aortic and tricuspid valve apparatus (annulus, leaflets, papillary muscles, and chordae tendineae). These parameters were compared between the DLR, FBP, and hybrid IR methods. Results: DLR provided higher Hounsfield unit (HU) values in the aorta and similar attenuation in the fat and muscle compared with FBP and hybrid IR. The image noise in HU was significantly lower in DLR (12.6 ± 2.2) than in hybrid IR (24.2 ± 3.0) and FBP (54.2 ± 9.5) (p < 0.001). The SNR and CNR were significantly higher in the DLR group than in the FBP and hybrid IR groups (p < 0.001). In the coronary stent, the mean value of ERS was significantly higher in DLR (1260.4 ± 242.5 HU/mm) than that of FBP (801.9 ± 170.7 HU/mm) and hybrid IR (641.9 ± 112.0 HU/mm). The mean value of ERD was measured as 0.8 ± 0.1 mm for DLR while it was 1.1 ± 0.2 mm for FBP and 1.1 ± 0.2 mm for hybrid IR. The subjective visual scores were higher in the DLR than in the images reconstructed with FBP and hybrid IR. Conclusion: DLR reconstruction provided better images than FBP and hybrid IR reconstruction.

A Fast Battery Charger for USN Applications

Otgonbaatar Gombo, Bieng-Chearl Ahn 충북대학교 컴퓨터정보통신연구소 2013 컴퓨터정보통신연구 Vol.21 No.1

This paper presents an implementation of a supercapacitor-based fast battery charger for USN sensor nodes. Our goal is to charge the sensor node battery in as short as possible time. In order to shorten the charging time, we first charge a pack of supercapacitors, which will slowly charge a battery in the sensor node. The implemented charging system consists of two parts, a portable charger and a battery unit. The portable charger includes a 200-F pack of supercapacitors and two supercapacitor chargers. The battery unit includes a 400-F pack of supercapacitors, a step-up converter, a lithium battery charger and a lithium battery. The supercapacitor packs in the portable charger and the battery unit are charged up to 10V and 5V respectively. The sensor node battery unit can be charged in 6 minutes.

Research Design to Isolate and Improve the Properties of Cr (VI) Resistant Bacteria from the Wastewater of a Central Treatment Plant

Naranzul Otgonbaatar 한국신재생에너지학회 2021 AFORE Vol.2021 No.10

A 3‐20GHz Vivaldi Antenna with Modified Edge

Bieng-Chearl Ahn, Otgonbaatar Gombo 충북대학교 컴퓨터정보통신연구소 2013 컴퓨터정보통신연구 Vol.21 No.1

A wideband elliptically-tapered-aperture Vivaldi antenna is proposed in this paper. The tapered aperture improves the lowfrequency impedance matching. The antenna is printed on a Teflon substrate and fed by a microstrip line. The size of the antenna is 92.9mm x 100.4mm x 0.787mm. The design, fabrication and measurement of the proposed antenna are presented.

Japan's Mongolian Connection in North Korea

Julian Dierkes,Otgonbaatar Byambaa 제주평화연구원 2013 JPI Peace Net Vol.2013 No.29

관상동맥 CT 조영 검사 시, 초 고해상도 딥러닝 알고리즘이 적용된 스텐트 영상의 진단적 가치

전상현,고동희,전필현,고성민,Otgonbaatar, Chuluunbaatar 대한CT영상기술학회 2024 대한CT영상기술학회지 Vol.26 No.1

최근 발전하는 인공지능 영상재구성 기법의 발전으로 현존하는 가장 정밀한 0.25 mm 다중 검출기 기반 초고해상도 딥러닝 영상재구성 기법의 개발로 관상동맥 스텐트 내강의 정확도에 대해 평가하고자 한다. 이 연구는 환자 연구와 팬텀 연구로 구분하였고, 동일 환자에게서 필터 보정 역투영법, 반복적 재구성 기법, 딥러닝 재구성기법, 인공지능 초고해상도 재구성기법 총 4가지 방법으로 영상을 재구성하였다. 이미지 품질을 객관적으로 평가하기 위해 각 데이터에 대해 4가지 매개 변수인 영상잡음, CT 밀도, 신호 대 잡음비, 대조도 대 잡음비를 분석하였다. 팬텀 연구는 인체모형 흉부 팬텀 내 관상동맥을 표현할 수 있도록 라텍스 넬라톤 멸균 카테터를 설치하였고, 각각의 카테터 내에는 관상동맥 스텐트(내경 2.5 mm, 3.5 mm)를 삽입시켜 CT 제조사 별로 여러 가지 재구성 기법(FBP, IR, DLR, UHR-DLR)을 사용하여 영상을 획득하였다. 에지 상승 거리(edge rise distance, ERD), 에지 상승 기울기(Edge rise slope, ERS) 통해 스텐트 선명도 평가를 하였다. UHR-DLR으로 재구성한 관상 동맥의 평균 SNR과 CNR이 DLR로 재구성한 평균 SNR과 CNR에 비해 각각 29.2 %, 36.4 % 향상되었음을 보여주었다. UHR-DLR에서 이미지 노이즈는 약 21.4 % 감소했다. 관상동맥 스텐트 팬텀으로 CT 제조사별 측청된 ERS 평균값은 Aquilion ONE Prism(Canon)의 UHR-DLR에서 가장 높은 수치로 나왔고, ERD 값은 CT 제조사별마다 유의한 차이를 나타냈다. UHR-DLR은 FBP, HIR, DLR 비교하여 이미지 선명도가 향상되고 이미지 노이즈 및 블루밍 인공물이 감소하여 관상동맥 윗부분의의 윤곽을 더욱 명확하게 보여주었을 뿐만 아니라, 스텐트 지주 구조 및 스텐트 내강을 명확하게 나타냈다. Recently, with the advancement of artificial intelligence image reconstruction technology, we are attempting to evaluate the accuracy of coronary artery stent lumen by developing ultra-high-resolution deep learning image reconstruction technology based on the most accurate 0.25mm multi-detector available. This study was divided into patient studies and phantom studies. Images were reconstructed in the same patient using four different methods: filter correction reverse projection, repetitive reconstruction, deep learning reconstruction, and artificial intelligence ultra-high resolution reconstruction. To objectively evaluate image quality, four parameters, image noise, CT density, signal-to-noise ratio, and contrast-to-noise ratio, were analyzed for each dataset. The phantom study installed a latex Nelaton sterilized catheter to express the coronary artery in the dummy chest phantom. Subsequently, a coronary stent (2.5mm and 3.5mm in diameter) was inserted into each catheter. Images were obtained using various reconstruction techniques (FBP, IR, DLR, and UHR-DLR) for each CT manufacturer. Stent clarity was evaluated using edge rise distance (ERD) and edge rise slope (ERS). We showed that the average Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) of coronary arteries reconstructed with Ultra-High Resolution Deep Learning Reconstruction (UHR-DLR) improved by 29.2% and 36.4% compared to those reconstructed with DLR, respectively. Image noise was reduced by about 21.4% in UHR-DLR. The ERS average value of the coronary stent phantom measured by the CT manufacturers was highest in the UHR-DLR of Aquilion ONE Prism (Canon), and the ERD value is statistically significant for each CT manufacturer. Compared to FBP, HIR, and DLR, UHR-DLR not only improved image clarity and reduced image noise and blooming artifacts but also clearly showed the stent support structure and stent lumen.

한국 프랜차이즈 커피전문점의 서비스품질이 고객만족 및 재방문의도에 미치는 영향2) -몽골 진출 한국 커피숍 브랜드를 중심으로-

김원종 ( Wonjong Kim ),오트건바타르노민 ( Nomin Otgonbaatar ),박귀정 ( Gwijeong Park ) 한국유통물류정책학회 2020 유통물류연구 Vol.7 No.4

본 연구는 몽골에 진출해 있는 한국 프랜차이즈 커피전문점의 성공요인을 분석하기 위하여 서비스품질이 고객만족 및 재방문의도에 어떠한 영향을 미치는지를 규명하는 것을 목적으로 한다. 본 연구의 구체적인 목적은 다음과 같다. 첫째, 프랜차이즈 커피전문점 서비스품질 변수인 인적서비스품질, 음료품질, 접근성, 메뉴다양성, 물리적환경, 편의시설이 고객만족 및 재방문의도에 미치는 영향을 규명하고, 둘째, 서비스품질과 고객만족의 관계에서 브랜드글로벌성의 상호작용 효과를 분석하고자 한다. 본 연구의 실증분석을 위하여 한국 커피전문점을 이용하는 몽골 울란바토르에 거주하는 일반 시민들을 대상으로 2020년 4월 1일부터 2020년 5월 1일까지 온라인설문조사를 실시하였다. 설문조사를 바탕으로 서비스품질이 고객만족에 미치는 영향을 실증분석하기 위하여 회귀분석을 실시하였으며, 분석결과 서비스품질의 하위차원으로 구성한 음료품질을 제외한 인적서비스품질, 접근성, 메뉴다양성, 물리적환경, 편의시설은 고객만족에 유의미한 정(+)의 영향을 미치는 것으로 나타났으며, 또한 고객만족은 재방문의도에 유의미한 영향을 미치는 것으로 나타났다. 서비스품질의 고객만족과의 관계에서 브랜드글로벌성의 상호작용을 분석한 결과, 브랜드글로벌성은 서비스품질의 하위차원 중 인적서비스품질을 제외한 음료품질, 접근성, 메뉴다양성, 물리적환경, 편의시설 차원과 고객만족의 관계에서 유의미한 상호작용효과가 있는 것으로 확인되었다. The purpose of this study is to investigate how service quality affects customer satisfaction and intention to revisit in order to analyze the success factors of Korean franchise coffee shops in Mongolia. The specific purpose of this study can be summarized as follow. First, This study investigates the effects of service quality variables such as human service quality, beverage quality, accessibility, menu diversity, physical environment, and facilities on customer satisfaction and revisit intention. Second, the study aims to analyze the interaction effect of brand globality in the relationship between service quality and customer satisfaction. For the purpose of empirical study, an online survey has been conducted from April 1, 2020 to May 1, 2020 for Mongolian citizens who use Korean coffee shops in Ulaanbaatar, Mongolia.. Based on the survey, a regression analysis has been conducted to empirically analyze the effect of service quality on customer satisfaction. As a result of the analysis, it was found that human service quality, accessibility, menu diversity, physical environment, and facilities, excluding beverage quality composed of the sub-dimensions of service quality, had a significant positive effect on customer satisfaction. And customer satisfaction was found to have a significant influence on the intention to revisit. As results of interaction analysis for investigating interaction effect of brand globality inbetween service quality and customer satisfaction, brand globality was found to have a significant interaction effect in the relationship between sub-dimensions of service quality(beverage quality, accessibility, menu diversity, physical environment, and facilities) and customer satisfaction. However, it did not show significant interaction effect in the relationship of human service quality and customer satisfaction.

Design of an E-plane Ring Hybrid Coupler in a Rectangular Waveguide

Tsend Shijirbaatar,Dong-Kook Lee,Otgonbaatar Gombo,Jae-Hoon Bang,Bierng-Chearl Ahn 한국정보기술학회 2012 한국정보기술학회논문지 Vol.10 No.7

Rectangular waveguide ring hybrid couplers are often used in combining, subtracting and dividing microwave signal in waveguides. In this paper, we present the optimum design and experimental verification of an E-plane 180° ring hybrid coupler in a rectangular waveguide. Using an electromagnetic simulation tool, the optimum dimensions of the ring hybrid coupler are obtained for a wideband performance at various operating frequencies of the standard WR-28 rectangular waveguide. The resultant design data can be used for an E-plane ring hybrid coupler in any standard rectangular waveguide. To verify the validity of the design, a ring hybrid coupler operating at 35GHz is fabricated using the split-block technique and its performance is measured. Measured results agree well with the simulation. Measurements of the fabricated coupler show a reflection coefficient less than -20 dB, an isolation greater than 20dB, an amplitude deviation within +0.3/-0.6dB and phase deviation within +6.5°/-5.5° over 33.4-37.2GHz(10.8% bandwidth).

CycleGAN과 Super Resolution을 이용한 EPI 기반의 뇌 MR 영상의 화질 개선

손유성(YuSeoung Son),출롱 바타르(Chuluunbaatar Otgonbaatar),심학준(HackJoon Shim),홍영택(YoungTaek Hong),하지영(JiYoung Ha),백혜진(HyeJin Baek) 한국정보과학회 2022 한국정보과학회 학술발표논문집 Vol.2022 No.06

준등방성 방사패턴을 가지는 평판 다이폴 안테나

이제선(Jea-Sun Lee),Gombo Otgonbaatar(오곤바타 검보),윤금노(Keum-No Yoon),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2011 한국정보기술학회논문지 Vol.9 No.1

In this paper, a planar dipole with a quasi-isotropic radiation pattern is proposed for use in 2.45㎓ ZigBee communications. A quasi-isotropic radiation pattern is realized by employing a C-shaped dipole electrode pattern on the FR-4 substrate. The antenna electrode shape is optimized using a commercial software so that the dipole shows minimum gain difference, wide frequency bandwidth and good impedance matching performances. The designed antenna is fabricated and its performance is measured. Measured performances of the fabricated antenna are 1.9㏈i maximim gain, 6.9㏈ gain difference, and 310㎒ bandwidth, which are in good agreement with the design goal.