Cardiac Manifestations of Coronavirus Disease 2019 (COVID-19): a Multicenter Cohort Study

Kim Minkwan,Nam Jong-Ho,Son Jang-Won,Kim Sun Oh,Son Nak-Hoon,Ahn Chul-Min,심지영,홍그루,Kim In-Cheol,Choi Jinwoo,Kang Seung-Mo,Choi Yeoung Ho,Yoon Hae Kyoung,엄재선,정인현 대한의학회 2020 Journal of Korean medical science Vol.35 No.40

Background: This study aimed to investigate the cardiac manifestations of coronavirus disease 2019 (COVID-19). Methods: From February to March 2020, we prospectively and retrospectively enrolled consecutive patients diagnosed with COVID-19. Patient's data such as the demographic characteristics, symptoms, vital signs, laboratory and radiologic findings, electrocardiographic, and echocardiographic data, including the global longitudinal strain (GLS) of both ventricles, were obtained. Results: Forty patients (median age, 58 years; 50% men) were enrolled in the initial analysis. Patients were classified into severe and nonsevere groups based on the current guidelines. The 13 patients in the severe group were significantly older, had a greater prevalence of bilateral pneumonia and leukocytosis, and higher aspartate transaminase levels than patients in the nonsevere group. Patients in the severe group had a slightly lower left ventricular ejection fraction (LVEF) than those in the nonsevere group (median [interquartile range], 61.0% [58.5%, 62.3%] vs. 66.7% [60.6%, 69.8%], P = 0.015). In a subgroup of 34 patients in whom GLS could be analyzed, patients in the severe group had a significantly impaired left ventricular GLS (LVGLS) than those in the nonsevere group (−18.1% [−18.8%, −17.1%] vs. −21.7% [−22.9%, −19.9%], P = 0.001). There were no significant differences in total wall (RVGLStotal, −19.3% [−23.9%, −18.4%] vs. −24.3% [−26.0%, −22.6%], P = 0.060) and free wall (RVGLSfw, −22.7% [−27.2%, −18.6%] vs. −28.8% [−30.4%, −24.1%], P = 0.066) right ventricle GLS (RVGLS). Conclusion: Patients with severe COVID-19 had lower LVEF and LVGLS. RVGLS was not different between patients with severe and nonsevere COVID-19.

The Effects of Radiofrequency Catheter Ablation for Atrial Fibrillation on Right Ventricular Function

Minkwan Kim,Jae-Sun Uhm,Je-Wook Park,SungA Bae,In Hyun Jung,Seok-Jae Heo,Daehoon Kim,Hee Tae Yu,Tae-Hoon Kim,Boyoung Joung,Moon-Hyoung Lee 대한심장학회 2024 Korean Circulation Journal Vol.54 No.4

Background and Objective: The effects of radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) on right ventricular (RV) function are not well known. Methods: Patients who underwent RFCA for AF and underwent pre- and post-procedural echocardiography were enrolled consecutively. Fractional area change (FAC), RV free-wall longitudinal strain (RVFWSL), and RV 4-chamber strain including the ventricular septum (RV4CSL) were measured. Changes in FAC, RVFWSL, and RV4CSL before and after RFCA were compared among paroxysmal AF (PAF), persistent AF (PeAF), and long-standing persistent AF (LSPeAF) groups. Results: A total of 164 participants (74 PAF, 47 PeAF, and 43 LSPeAF; age, 60.8 ± 9.8 years; men, 74.4%) was enrolled. The patients with PeAF and LSPeAF had worse RV4CSL (p<0.001) and RVFWSL (p<0.001) than those with PAF and reference values. Improvements in RVFWSL and RV4CSL after RFCA were significant in the PeAF group compared with the PAF and LSPeAF groups (ΔRV4CSL, 8.4% [5.1, 11.6] in PeAF vs. 1.0% [−1.0, 4.1] in PAF, 1.9% [−0.2, 4.4] in LSPeAF, p<0.001; ΔRVFWSL, 9.0% [6.9, 11.5] in PeAF vs. 0.9% [−1.4, 4.9] in PAF, 1.0% [−1.0, 3.6] in LSPeAF, p<0.001). In patients without recurrence, improvements in RVFWSL and RV4CSL after RFCA were significant in the PeAF group compared to the LSPeAF group. Conclusions: RV systolic function is more impaired in patients with PeAF and LSPeAF than in those with PAF. RV systolic function is more improved after RFCA in patients with PeAF than in those with PAF or LSPeAF.

Tuning Mechanical and Optoelectrical Properties of Poly(3-hexylthiophene) through Systematic Regioregularity Control

Kim, Jin-Seong,Kim, Jae-Han,Lee, Wonho,Yu, Hojeong,Kim, Hyeong Jun,Song, Inho,Shin, Minkwan,Oh, Joon Hak,Jeong, Unyong,Kim, Taek-Soo,Kim, Bumjoon J. American Chemical Society 2015 Macromolecules Vol.48 No.13

<P>While the regioregularity (RR) of conjugated polymers is known to have a strong influence on their inherent properties, systematic study of the RR effect has been limited due to the lack of a synthetic methodology. Herein, we successfully produced a series of poly(3-hexylthiophene)s (P3HTs) having a wide range of RR from 64 to 98%. Incorporation of controlled amounts of head-to-head (H-H) coupled dimer in modified Grignard metathesis polymerization allows a facile tuning of the RR of the P3HTs with comparable molecular weight and low polydispersity. Then, we investigated the effect of RR on structural, electrical, and mechanical properties of P3HTs in which a higher content of H-H regio-defects, namely lower RR, systematically lowered the degree of crystallinity. Although high RR P3HT (98%) had higher charge carrier mobility (1.81 x 10(-1) cm(2) V-1 s(-1)), its strong crystallinity induced high brittleness and stiffness, resulting in device failure under a very small strain, as shown in tensile and bending tests. The tensile modulus was reduced significantly from 287 MPa (RR 98%) to 13 MPa (RR 64%), and also the RR 64% P3HT film had much better mechanical resilience with an order of magnitude higher elongation at break than that of the RR 98% polymer. Our findings suggest that the mechanical and electrical properties of conjugated polymers can be systematically tuned by controlling the RR to meet the purposes of various organic electronic applications, i.e., flexible portable devices vs high-performance panels.</P>

가치단계 확장에 따른 u-City 수익모델 도출방법에 관한 연구

김민관(Kim, MinKwan),김정민(Kim, JungMin),이차영(Lee, ChaYoung),김일겸(Kim, IlKyum),한창희(Han, ChangHee) 한국IT서비스학회 2009 한국IT서비스학회 학술대회 논문집 Vol.2009 No.1

본 연구는 u-City에서 제공하는 u-서비스의 새로운 수익모델 창출을 위한 접근 방안으로 사용자 중심의 접근을 시도 했으며 u-서비스에 사용자가 부여하는 가치에 중점을 두고 연구를 진행하였다. 사용자가 부여한 가치의 확장을 통해 새로운 서비스 또는 수익모델 창출의 기회를 발굴하고자 하였다. 연구 결과 사용자가 부여하는 1차적인 가치는 서비스와 관련된 다양한 가치로 그 의미가 확장될 수 있었다. 확장된 가치를 근간으로 기존에 고려하지 못한 새로운 서비스와 수익모델을 발굴할 수 있는 기회를 포착할 수 있었다. u-서비스의 수익모델 창출을 위한 새로운 접근 방안으로써 사용자 가치에 대한 고려는 실질적으로 서비스를 사용할 사용자에 기초한 관점으로 사용자 중심의 u-서비스 개발 및 수익모델 발굴에 중요한 연구가 될 것이라 생각된다.

Early Surgery versus Watchful Waiting in Patients with Moderate Aortic Stenosis and Left Ventricular Systolic Dysfunction

Inki Moon,Minkwan Kim,Jae-Woong Choi,Jun-Bean Park,Ho-Young Hwang,Hyung-Kwan Kim,Yong Jin Kim,Kyung-Hwan Kim,Ki-Bong Kim,Dae-Won Sohn,Seung-Pyo Lee 대한심장학회 2020 Korean Circulation Journal Vol.50 No.9

Background and Objectives: Severe aortic stenosis (AS) with left ventricular systolic dysfunction (LVSD) is a class I indication for aortic valve replacement (AVR) but this recommendation is not well established in those at the stage of moderate AS. We investigate the clinical impact of AVR among patients with moderate AS and LVSD. Methods: From 2001 to 2017, we consecutively identified patients with moderate AS and LVSD, defined as aortic valve area 1.0–1.5 cm2 and left ventricular ejection fraction <50%. The primary outcome was all-cause death. The outcomes were compared between those who underwent early surgical AVR (within 2 years of index echocardiography) at the stage of moderate AS versus those who were followed medically without AVR at the outpatient clinic. Results: Among 255 patients (70.1±11.3 years, male 62%), 37 patients received early AVR. The early AVR group was younger than the medical observation group (63.1±7.9 vs. 71.3±11.4) with a lower prevalence of hypertension and chronic kidney disease. During a median 1.8-year follow up, 121 patients (47.5%) died, and the early AVR group showed a significantly lower all-cause death rate than the medical observation group (5.03PY vs. 18.80PY, p<0.001). After multivariable Cox-proportional hazard regression adjusting for age, sex, comorbidities, and laboratory data, early AVR at the stage of moderate AS significantly reduced the risk of death (hazard ratio, 0.43; 95% confidence interval 0.20–0.91; p=0.028). Conclusions: In patients with moderate AS and LVSD, AVR reduces the risk of all-cause death. A prospective randomized trial is warranted to confirm our findings.

Association Between Aortic Valve Sclerosis and Clonal Hematopoiesis of Indeterminate Potential

Kim Minkwan,Kim Jin Ju,Lee Seung-Tae,Shim Yeeun,Lee Hyeonah,Bae SungA,Son Nak-Hoon,Shin Saeam,Jung In Hyun 대한진단검사의학회 2024 Annals of Laboratory Medicine Vol.44 No.3

Background: The mechanism and medical treatment target for degenerative aortic valve disease, including aortic stenosis, is not well studied. In this study, we investigated the effect of clonal hematopoiesis of indeterminate potential (CHIP) on the development of aortic valve sclerosis (AVS), a calcified aortic valve without significant stenosis. Methods: Participants with AVS (valves ≥2 mm thick, high echogenicity, and a peak transaortic velocity of <2.5 m/sec) and an age- and sex-matched control group were enrolled. Twenty-four CHIP genes with common variants in cardiovascular disease were used to generate a next-generation sequencing panel. The primary endpoint was the CHIP detection rate between the AVS and control groups. Inverse-probability treatment weighting (IPTW) analysis was performed to adjust for differences in baseline characteristics. Results: From April 2020 to April 2022, 187 participants (125 with AVS and 62 controls) were enrolled; the mean age was 72.6±8.5 yrs, and 54.5% were male. An average of 1.3 CHIP variants was observed. CHIP detection, defined by a variant allele frequency (VAF) of ≥0.5%, was similar between the groups. However, the AVS group had larger CHIP clones: 49 (39.2%) participants had a VAF of ≥1% (vs. 13 [21.0%] in the control group; P=0.020), and 25 (20.0%) had a VAF of ≥2% (vs. 4 [6.5%]; P=0.028). AVS is independently associated with a VAF of ≥1% (adjusted odds ratio: 2.44, 95% confidence interval: 1.11–5.36; P=0.027). This trend was concordant and clearer in the IPTW cohort. Conclusions: Participants with AVS more commonly had larger CHIP clones than age- and sex-matched controls. Further studies are warranted to identify causality between AVS and CHIP.

Preparation and Characterization of Flame Retardant High Impact Polystyrene

Minkwan Kim(김민관),Mi Jung Lee(이미정),Han Do Ghim(김한도) 한국고분자학회 2017 폴리머 Vol.41 No.1

난연성 고충격 폴리스티렌(HIPS)의 합성을 위하여 라디칼계 부가반응을 통해 트리페닐포스페이트(TPP)를 그래프트하였다. FTIR과 <SUP>1</SUP>H NMR 분석을 통하여 TPP의 부가반응이 성공적으로 이루어졌음과 HIPS를 구성하는 폴리부타디엔(PB)의 이중결합이 감소하였음을 확인하였다. 또한 TPP의 부가에 따른 이중결합의 감소는 Izod 충격강도의 감소를 통해 확인하였다. 그래프트된 TPP가 TPP@HIPS의 비결정영역에 존재하고 있음은 <SUP>31</SUP>P NMR 분석을 통해 확인하였다. TGA 분석의 잔존 char yield로부터 TPP@HIPS의 열안정성이 향상되었음을 유추할 수 있었다. TPP@HIPS의 잔존 char yield는 600 ℃ 이상에서 16.65 wt%를 보였으며, 미처리 HIPS(pHIPS)의 경우에는 잔존하는 char가 존재하지 않았다. 한계산소지수(LOI) 수치는 pHIPS와 TPP@HIPS에 있어 유의미한 차이를 나타내지 않았으나, UL94 수직시험법을 통해 TPP@HIPS가 V-1 등급의 우수한 난연성을 나타냄을 확인하였다. A triphenyl phosphate (TPP) graft high impact polystyrene (HIPS) (TPP@HIPS) is synthesized to prepare flame retarding HIPS via radical addition reaction of TPP. From FTIR and <SUP>1</SUP>H NMR analyses, successful addition reaction of the TPP and decreases of the amount of double bond of polybutadiene parts in HIPS were confirmed. Reduction of the amount of double bond by addition of TPP can also be confirmed through comparison of Izod impact strength values. From <SUP>31</SUP>P NMR characterization, it can be supposed that the TPP exists as amorphous phase in TPP@HIPS. Thermal stability of the TPP@HIPS is improved, which is deduced by increasing residual char yield observed from TGA analyses. Residual char content of the TPP@HIPS at over 600 ℃ was 16.65 wt%, whereas there was no residue for pure HIPS (pHIPS). There are not significant differences in limited oxygen index (LOI) values of pHIPS and TPP@HIPS. However, the TPP@HIPS showed superior flame retardancy of V-1 rating in UL94 vertical test.

향상된 MUSIC 알고리즘을 통한 최적의 도래각 추정 및 빔포밍

김민관(Minkwan Kim),정민수(Minsoo Jeong),김선우(Sunwoo Kim) 한국통신학회 2017 한국통신학회 학술대회논문집 Vol.2017 No.11

참조 동작을 사용하지 않는 근골격계 캐릭터의 보행 모션 학습

김민관(Minkwan Kim),이윤상(Yoonsang Lee) 한국컴퓨터그래픽스학회 2022 한국컴퓨터그래픽스학회 학술대회 Vol.2022 No.7

모션 특징을 이용한 측 후방 사각지대 차량 검출 알고리즘

김민관(Minkwan Kim),전대홍(Daehong Jeon),강호준(Hojune Kang),손수락(Surak Shon),최태호(Taeho Choi) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2007 No.11