• International Journal of Arrhythmia
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• 제18권2호
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• pp.66-76
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• 2017

Background and Objectives: Although an anterior linear ablation is an effective lesion set in radiofrequency catheter ablation (RFCA) for longstanding persistent atrial fibrillation (L-PeAF), its durability for bidirectional block (BDB) is only about 60% at repeat procedure. We hypothesized that changes in electrocardiogram (ECG) may predict an anterior line block state and the clinical outcome of L-PeAF ablation. Subjects and Methods: We studied 304 L-PeAF patients (77% male, $60{\pm}10yrs$), who consistently underwent RFCA Dallas lesion set (circumferential pulmonary vein isolation, posterior box lesion, and anterior line) protocol with subsequent comparison of pre-procedural and post-procedural P wave axes, and one year follow-up (n=205) sinus rhythm (SR) ECGs. Results: 1. P wave axis shifted inferiorly at immediate post-procedure (p<0.001), and was independently correlated with BDB of anterior line (${\ss}=10.4$, 95% confidence interval [CI] 2.79-17.94, p=0.008). 2. The degree of post-procedural inferior shift of P wave axis did not reflect clinical recurrence within one-year (n=205, p=0.923), potentially due to conduction recovery of an anterior line. However, among 160 patients without clinical recurrence within one-year, P wave axis at one-year ECG was independently associated with very late recurrence of AF after one-year (n=160, hazard ratio [HR] 0.98; 95% CI 0.97-0.99, p=0.001), during $45.6{\pm}16.7$ months of follow-up. 3. Among 22 patients who underwent repeat procedures, P wave axis shift was more significant in patients with maintained BDB of an anterior line than in those without (p=0.015). Conclusion: An inferior shift of P wave axis reflects the achievement and the maintenance of an anterior line BDB, and is associated with better long-term clinical outcome after catheter ablation for L-PeAF based on Dallas lesion set.

• The Korean Journal of Pain
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• v.34 no.1
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• pp.82-93
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• 2021

Background: This study used bibliometric analysis of articles published about the topic of regional anesthesia from 1980-2019 with the aim of determining which countries, organizations, and authors were effective, engaged in international cooperation, and had the most cited articles and journals. Methods: All articles published from 1980-2019 included in the Web of Science database and found using the keywords regional anesthesia/anaesthesia, spinal anesthesia/anaesthesia, epidural anesthesia/anaesthesia, neuraxial anesthesia/anaesthesia, combined spinal-epidural, and peripheral nerve block in the title section had bibliometric analysis performed. Correlations between the number of publications from a country with gross domestic product (GDP), gross domestic product (at purchasing power parity) per capita (GDP PPP), and human development index (HDI) values were investigated with the Spearman correlation coefficient. The number of articles that will be published in the future was estimated with linear regression analysis. Results: Literature screening found 11,156 publications. Of these publications, 6,452 were articles. The top 4 countries producing articles were United States of America (n = 1,583), Germany (585), United Kingdom (510), and Turkey (386). There was a significant positive correlation found between the GDP, GDP PPP, and HDI markers for global countries with publication productivity (r = 0.644, P < 0.001; r = 0.623, P < 0.001, r = 0.542, P < 0.001). The most productive organizations were Harvard University and the University of Toronto. Conclusions: This comprehensive study presenting a holistic summary and evaluation of 6,452 articles about this topic may direct anesthesiologists, doctors, academics, and students interested in this topic.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.2
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• pp.176-183
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• 2022

High-purity waste CNTs were mixed into cement mortar to manufacture heat-generating concrete that can use low voltage power, and carbon fiber and waste cathode materials were also used improve the conductivity of the mortar. The waste CNTs were analyzed to have a high concentration of multi-walled CNTs, and substituted liquid type waste CNTs were used during mortar mixing in order to increase dispersibility. The temperature change of the mortar with CNT was evaluated when using electric power below DC 24 V in order to utilize a small self-generation facility such as small solar power module when the mortar heats up and to minimize electromagnetic waves. When liquid-type waste CNTs were applied and a voltage of DC 24 V was introduced, it rose to 60 ℃ in a 200 × 100 × 50 mm mortar block specimen. The field applicability of self heating mortar with waste CNT was sufficient and also the amount of change in heat energy in mortar with liquid type waste CNT, carbon fiber and waste cathode materials is more effective compared to it of other variables.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.28-31
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• 2018

Phase diagrams of electron- and hole-doped $Sr_2VO_3FeAs$ are investigated using Co and Mn substitution at Fe site. Metallic nature survives only for Co (electron) doping, not for Mn (hole) doping. The conductivity of $Sr_2VO_3(Fe,M)As$ (M=Mn,Co) is sensitive to the structural modification of FeAs microstructure rather than carrier doping. This finding implies that the FeAs layer plays a dominant role on the charge conduction, thus the $SrVO_3$ layers should be considered as an insulating block. Also, we found that the superconductivity is rapidly suppressed by both dopants. This result is different from the conventional behavior that superconductivity is induced by doping in the most of Fe pnictides. Our finding strongly supports the uniqueness of $Sr_2VO_3FeAs$ among the Fe pnictide superconductors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.945-956
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• 1999

This work reports a set of approximate analytical solutions describing the initial transient process of close-contact melting between a rectangular parallelepiped solid and a flat plate on which either constant temperature or constant heat flux is imposed. Not only relative motion of the solid block tangential to the heating plate, but also the density difference between the solid and liquid phase is incorporated in the model. The thin film approximation reduces the force balance between the solid weight and liquid pressure, and the energy balance at the melting front into a simultaneous ordinary differential equation system. The normalized model equations admit compactly expressed analytical solutions which include the already approved two-dimensional solutions as a subset. In particular, the normalized liquid film thickness is independent of all pertinent parameters, thereby facilitating to define the transition period of close-contact melting. A unique behavior of the solid descending velocity due to the density difference is also resolved by the present solution. A new geometric function which alone represents the three-dimensional effect is introduced, and its properties are clarified. One of the representative results is that heat transfer is at least enhanced at the expense of the increase in friction as the cross-sectional shape deviates from the square under the same contact area.

• Journal of Chest Surgery
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• v.28 no.3
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• pp.233-236
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• 1995

Subepicardial space is one of the regions in which fat in moderate amount is normally deposited. When excess deposits of epicardial fat occur, penetration or infiltration of fat into the connective tissues between muscle bundles is observed. In some cases with very extensive involvement of epicardial fat,myocardial insufficiency and conduction system defect such as heart block have been implicated. More fat is deposited over the right ventricle than over left and the anterior surface contains more fat than dose the posterior surface. We studied 40 patients who underwent open heart surgery under the cardiopulmonary bypass. This study was designed to evaluate the percentage of the area of epicardial fat of the right ventricular anterior surface, which is more accessible area during the operative procedure. Other variables included thickness of subcutanous tissue of anterior chest wall, the ratio of waist to hip circumference, body weight and age. In conclusion, the amount of the epicardial fat correlates with thickness of the subcutaneous fat of the anterior chest wall and simple linear regression analysis indicates good correlation with body weight. Increased age results in large amount of epicardial fat.

• The Journal of Internal Korean Medicine
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• v.22 no.4
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• pp.755-759
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• 2001

Acute Myocardica Infarction has high mortality and bad prognosis. We treated a 68 year-old female patient of acute myocardiac infacrtion to follow cerebral infarction. The chief complainment is right hemiplegia, dyspnea, chest discomfort, palpitation, anxiety, insomnia. The prognosis cannot be good, Because she has anterior wall infarction, cardiomegaly, conduction block, hypertention and she is 68 years old. We treated her with chiefly Nogyongdaebo-tang and Gongjin-dan, and gradually increased momentum. also we used self west medicine. The chief complainment was improved. She became to do cane walking by herself.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.321-325
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• 2000

Gasket of vehicle engine maintains airtight between cylinder head and engine block under high temperature and pressure, and plays important role in heat conduction of engine. And the characterization of the nonlinear behavior of metal gasket fer various bead shapes is very important as basic research for estimation of gasket durability. But it is very difficult to analyze the behavior of gasket In real experiment. In this paper, to analysis effects of the bead shape on the nonlinear behavior of cylinder head gasket under uniform pressure, the virtual experiment using the nonlinear finite element method was performed. Results are analyzed with residual deformation and the sealing pressure. With the increase of the height and the width of bead, the residual deformation and the sealing pressure increase. And if the height is very high and the width is very narrow, the wrinkles are occurred in the gasket while working.

• Nuclear Engineering and Technology
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• v.46 no.5
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• pp.641-654
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• 2014

A new computer code, named CORONA (Core Reliable Optimization and thermo-fluid Network Analysis), was developed for the core thermo-fluid analysis of a prismatic gas cooled reactor. The CORONA code is targeted for whole-core thermo-fluid analysis of a prismatic gas cooled reactor, with fast computation and reasonable accuracy. In order to achieve this target, the development of CORONA focused on (1) an efficient numerical method, (2) efficient grid generation, and (3) parallel computation. The key idea for the efficient numerical method of CORONA is to solve a three-dimensional solid heat conduction equation combined with one-dimensional fluid flow network equations. The typical difficulties in generating computational grids for a whole core analysis were overcome by using a basic unit cell concept. A fast calculation was finally achieved by a block-wise parallel computation method. The objective of the present paper is to summarize the motivation and strategy, numerical approaches, verification and validation, parallel computation, and perspective of the CORONA code.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1254-1263
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• 1990

The temperature distribution and heat flux of the inner cylinder wall of a 4-cycle turbocharged gasoline engine were calculated by a 2-dimensional coordinate transformation. Boundary conditions of the inner wall of the cylinder were taken from the results of diagnostic engine simulations. Results show that the ununiformity of inner wall temperature of the cylinder black can be reduced by a proper choice of the thickness of fin and the distance between two cylinder blocks.