Detection of Rapid Atrial Arrhythmias in SQUID Magnetocardiography

김기웅,권혁찬,김기담,이용호,김진목,김인선,임현균,박용기,김두상,임승평,Kim Kiwoong,Kwon Hyukchan,Kim Ki-Dam,Lee Yong-Ho,Kim Jin-Mok,Kim In-Seon,Lim Hyun-Kyoon,Park Yong-Ki,Kim Doo-Sang,Lim Seung-Pyung The Korean Superconductivity Society 2005 Progress in superconductivity Vol.7 No.1

We propose a method to measure atrial arrhythmias (AA) such as atrial fibrillation (Afb) and atrial flutter (Afl) with a SQUID magnetocardiograph (MCG) system. To detect AA is one of challenging topics in MCG. As the AA generally have irregular rhythm and atrio-ventricular conduction, the MCG signal cannot be improved by QRS averaging; therefore a SQUID MCG system having a high SNR is required to measure informative atrial excitation with a single scan. In the case of Afb, diminished f waves are much smaller than normal P waves because the sources are usually located on the posterior wall of the heart. In this study, we utilize an MCG system measuring tangential field components, which is known to be more sensitive to a deeper current source. The average noise spectral density of the whole system in a magnetic shielded room was $10\;fT/{\surd}Hz(a)\;1\;Hz\;and\;5\;fT/{\surd}Hz\;(a)\;100\;Hz$. We measured the MCG signals of patients with chronic Afb and Afl. Before the AA measurement, the comparison between the measurements in supine and prone positions for P waves has been conducted and the experiment gave a result that the supine position is more suitable to measure the atrial excitation. Therefore, the AA was measured in subject's supine position. Clinical potential of AA measurement in MCG is to find an aspect of a reentry circuit and to localize the abnormal stimulation noninvasively. To give useful information about the abnormal excitation, we have developed a method, separative synthetic aperture magnetometry (sSAM). The basic idea of sSAM is to visualize current source distribution corresponding to the atrial excitation, which are separated from the ventricular excitation and the Gaussian sensor noises. By using sSAM, we localized the source of an Afl successfully.

심자도용 접선성분자장 측정방식 스퀴드 센서열 설계

김기웅,이용호,권혁찬,김진목,김인선,박용기,이규원,Kim K.,Lee Y. H,Kwon H,Kim J. M,Kim I. S,Park Y. K,Lee K. W 한국초전도학회 2004 Progress in superconductivity Vol.6 No.1

We consider design factors for a SQUID sensor array to construct a 52-channel magnetocardiogram (MCG) system that can be used to measure tangential components of the cardiac magnetic fields. Nowadays, full-size multichannel MCG systems, which cover the whole signal area of a heart, are developed to improve the clinical analysis with high accuracy and to provide patients with comfort in the course of measurement. To design the full-size MCG system, we have to make a compromise between cost and performance. The cost is involved with the number of sensors, the number of the electronics, the size of a cooling dewar, the consumption of refrigerants for maintenance, and etc. The performance is the capability of covering the whole heart volume at once and of localizing current sources with a small error. In this study, we design the cost-effective arrangement of sensors for MCG by considering an adequate sensor interval and the confidence region of a tolerable localization error, which covers the heart. In order to fit the detector array on the cylindrical dewar economically, we removed the detectors that were located at the corners of the array square. Through simulations using the confidence region method, we verified that our design of the detector array was good enough to obtain whole information from the heart at a time. A result of the simulation also suggested that tangential-component MCG measurement could localize deeper current dipoles than normal-component MCG measurement with the same confidence volume; therefore, we conclude that measurement of the tangential component is more suitable to an MCG system than measurement of the normal component.

유해화학물질 노출과 대사증후군

김기웅,류향우,이미영,고경선,허경화,원용림,김태균,김민기,Kim, Gi-Ung,Ryu, Hyang-U,Lee, Mi-Yeong,Go, Gyeong-Seon,Heo, Gyeong-Hwa,Won, Yong-Rim,Kim, Tae-Gyun,Kim, Min-Gi 대한산업보건협회 2009 산업보건 Vol.249 No.-

Correction in the Principal Component Elimination Method for Neuromagnetic Evoked Field Measurements

김기웅,Hyukchan Kwon,In-Seon Kim,Jin-Mok Kim,Yong-Ho Lee,Yong-Ki Park 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.4

중소기업의 성장 관점에서 사내 기업가정신이 경영성과에 미치는 영향 실증분석

김기웅,김문선,Kim, Ki Woong,Kim, Moon Sun 한국벤처창업학회 2017 벤처창업연구 Vol.12 No.5

Entrepreneurship is an important factor not only for start-ups, but also for scale-up of businesses. In other words, the two aspects of establishment and growth of businesses must be balanced through entrepreneurship. However, it is true that entrepreneurship has been biased toward the former in previous researches and government policies. Here in this research, the causal relationships between the entrepreneurial characteristics of Korean firms and the performance of the company, which is measured by proposal, activity, and business performance are examined as a growth perspective. Based on these relationships, a model describing the operating mechanism of corporate entrepreneurship is derived and policy implications are provided. In conducting research, the hypotheses on the interrelationship of variables are builded using '2016 Entrepreneurship Situation Survey(Corporate)' data from Korea Entrepreneurship Foundation and analyzed by structural equation modeling. In addition, the moderating effect according to the firm size and the mediating effect between entrepreneurship and business performance are analyzed. As a result of this research, the fact that entrepreneurship affects business performance is identified and it is necessary to prioritize corporate vision and strategy for enhancement of entrepreneurship. In particular, necessity of operating system for SMEs is confirmed considering SMEs' entrepreneurship level. The implications of this research are expected to be applied by the government in establishing policy direction to enhance corporate entrepreneurship of SMEs in the future.

원자자력계를 이용한 생체자기측정

김기웅,Kim, Gi-Ung 한국광학회 2009 광학과 기술 Vol.13 No.1

제언 - 첨단 과학기술의 발전과 산업보건 연구의 접목

김기웅,Kim, Gi-Ung 대한산업보건협회 2018 산업보건 Vol.2018 No.-

Overweight of Korean Male Workers and Genetic Polymorphism of Insulin Receptor Substrate 1 (IRS1) Gene

김기웅,허경화,Yong Lim Won,Kyung Sun Ko,Tae Gyun Kim,Mi-Young Lee,Jungsun Park,Sang-Gi Paik 한국통합생물학회 2009 Animal cells and systems Vol.13 No.2

We have examined the hypothesis that the Gly972Arg variant of the insulin receptor substrate 1 (IRS1) gene is associated with the components contributing to overweight (obesity) and metabolic syndrome. We describe IRS1 genotype frequencies in 274 Korean men. The frequencies of Gly972Gly (G/G) and Gly972Arg (G/A variant) of the IRS1 gene were 88.3% and 11.7%, respectively, and the differences in frequencies between the overweight (BMI≥25 kg/m2) group and non-overweight (BMI<25 kg/m2) group were statistically significant. The subjects with G/A variant of IRS1 gene in non-overweight had significantly higher level of visceral fat thickness and adiponectin/leptin ratio than those with G/G alleles. In overweight group, the subjects with G/A variant of IRS1 gene also showed significantly higher level of insulin than those with G/G alleles. These results suggest that the IRS1 genetic polymorphism is involved in the occurrence of overweight, as well as metabolic syndrome. We have examined the hypothesis that the Gly972Arg variant of the insulin receptor substrate 1 (IRS1) gene is associated with the components contributing to overweight (obesity) and metabolic syndrome. We describe IRS1 genotype frequencies in 274 Korean men. The frequencies of Gly972Gly (G/G) and Gly972Arg (G/A variant) of the IRS1 gene were 88.3% and 11.7%, respectively, and the differences in frequencies between the overweight (BMI≥25 kg/m2) group and non-overweight (BMI<25 kg/m2) group were statistically significant. The subjects with G/A variant of IRS1 gene in non-overweight had significantly higher level of visceral fat thickness and adiponectin/leptin ratio than those with G/G alleles. In overweight group, the subjects with G/A variant of IRS1 gene also showed significantly higher level of insulin than those with G/G alleles. These results suggest that the IRS1 genetic polymorphism is involved in the occurrence of overweight, as well as metabolic syndrome.

Detection of an Acute Ischemic Phase Induced by Adenosine in the Myocardium by Using a SQUID Magnetocardiograph

김기웅,Hyukchan Kwon,Hyun-Kyoon Lim,Jin-Mok Kim,Namsik Chung,Yong-Ho Lee,Yong-Ki Park,Young-Guk Ko 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I

We show that the acute ischemic phase in the human heart invokes dynamic changes in magnetic field distribution recorded on the magnetocardiogram (MCG) of a patient who is undergoing acute ischemia induced by an intravenous injection of Adenosine. One of the finest superconductive electronic devices is a SQUID. By using the SQUID, we can record biomagnetic excitation of a heart and we call it MCG. Many research groups have been using an MCG system as a diagnostic tool for heart diseases. Recently, many reports on successful diagnosis of myocardial ischemia have been issued. Especially, MCGs in an emergency room were effective for diagnosing coronary artery diseases. To explain the effectiveness, we simulated the acute ischemic phase by using a two-dimensional cellular automata model describing electric excitation of the myocardium. As the result of the simulation, the acute ischemic phase was more dangerous than a progressed infarction because the acute ischemic phase caused ventricular fibrillation. A heart with ischemic tissue evoked a dynamic change in the myocardial currents and evoked even the reentry currents; Based on the simulation, the fragmentation of the reentry currents on the boundary of the tissue caused the dynamic change in the MCG. We concluded that successful early detection of the ischemic phase was possible by measuring the dynamic field change in the repolarization periods. To demonstrate our conclusion, we recorded 23 MCGs of 12 patients in acute myocardial ischemia induced by an intravenous injection of Adenosine and of 11 patients having a fixed infarction that was independent of the Adenosine injection. Then, we compared the degree of the dynamic field change before and after the injection for the two groups of patients. The result showed an obvious increase in the dynamic field change after the Adenosine injection only in the group with acute ischemia.

급성 납중독된 흰쥐의 이물질 대사효소의 활성도에 관한 연구

김기웅,송용범,장성근 ( Ki Woong Kim,Young Beam Song,Sung Keun Chang ) 생화학분자생물학회 1994 BMB Reports Vol.27 No.2

In rats treated with lead nitrate and/or red ginseng extract mixture we observed a change in the level of hepatic cytochrome P-450 and electron transport system for P-450 dependent reaction, and a content of zinc protoporphyrin (ZPP) and hemoglobin (Hb) in whole blood. The contents of cytochrome P-450 and b_5, and the activity of ECDEase, AHHase and NADPH-cytochrome C (P-450) reductase were slowly decreased according to the dosage of lead nitrate. On the other hand, the activity of NADH-bs reductase was increased according to the dosage of lead nitrate, but in case of treatment with red ginseng mixture, this enzyme activity was slightly decreased. In whole blood, the contents of hemoglobin and ZPP were not shown any critical change but lead content increased according to dosage of lead nitrate. These results suggest that content and activity of cytochrome P-450-dependent monooxygenase may be dependent on specificity of substrates and exposure duration.