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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.
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.
Ethanol이 Trichloroethylene 대사효소의 활성도와 유도성에 미치는 영향
김기웅,강성규,조영숙,이세휘,문영한,최병순,박상신,Kim, Ki-Woong,Kang, Seung-Kyu,Cho, Young-Sook,Lee, Sei-Hui,Moon, Young-Hahn,Choi, Byung-Soon,Park, Sang-Shin 대한예방의학회 1995 Journal of Preventive Medicine and Public Health Vol.28 No.1
This study was performed to find out the influences of ethanol on the metabolism of trichloroethylene(TRI) in rats. TRI in corn oil at the dosage of 150, 300, 600 mg/kg was injected peritoneally once a day for two days to two groups. In one group ethanol(4 g/kg) was taken orally 30 minutes before TRI injection, and the other group ethanol was not. The results of experiments are as follows: 1. The contents of cytochrome P-450 and $b_5$ had inverse relationship with in-jected TRI amounts in both groups. 2. The activity of NADPH P-450 reductase was decreased slowly in TRI injected group related with TRI amount, but decreased drastically in the group pretreated with ethanol. 3. The activity of NADH $b_5$ reductase had relationship with injected nt amount , but the statistical significance was found only in the groups of 300 and 600 mg/kg of TRI injected without relevance to ethanol when compared with the group that was not injected. 4. The activity of ADH was more decreased and ALDH activity was more increased in groups that TRI injected and ethanol was pretreated with ethanol groups than in group without any treatment. These results suggest that ethanol may inhibit epoxide formulation, the first step of TRI metabolism, and change from TCE-OH to TCA also.
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.
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.