Sungkyu Cho

We have proposed and fabricated a maximum power point tracking (MPPT) circuit for thermoelectric generator (TEG) without digital controller unit. The experimental and simulation results from the proposed MPPT circuit employing the boost cascaded-with-buck converter dealt with rapid variation of temperature and abrupt changes of load current have shown that the proposed method allows stable operation with high power transfer efficiency. The main advantage of proposed method is analog tracking cir

OBJECTIVES: We evaluated the outcomes of patients who underwent extracardiac Fontan circulation procedures (ECFP) and received 16-mm polytetrafluoroethylene conduits. METHODS: From June 1997 to May 2015, among the 408 patients who underwent ECFP, 66 patients (Group S) also received 16-mm polytetrafluoroethylene conduits. To compare this patient cohort with similarly sized patients who received larger conduits, a matched cohort (66 patients, Group L) was selected according to age and body weight.

OBJECTIVES: Mitral valve (MV) repairs have been performed in paediatric patients with congenital MV stenosis. However, congenital MV stenosis lesions are a heterogeneous group of lesions, and their repair remains challenging. METHODS: From March 1999 to September 2014, MV repair was performed in 22 patients with congenital MV stenosis. The median age was 10.3 months (ranging from 22 days to 9.1 years), and the mean body weight was 7.9 ± 4.0 kg at the time of the operation. Multiple-level left-si

Background: With the advances of cardiac surgery, the demand for an artificial prosthesis has increased, and this has led to the development and utilization of diverse alternative materials. We conducted this research to improve an artificial prosthesis by examining the changes of the physical qualities, the pressure related tensile strength, the change in elasticity and the thermostability of a xenograft valve (porcine) and pericardium (bovine, porcine) based on the type of fixation liquid we u

OBJECTIVES: Coarctation of the aorta (CoA) in adolescents and adults is relatively rare. Several operative techniques have been reported, but there is no consensus. METHODS: From November 1994 to July 2018, a total of 24 adolescents and adults underwent CoA repair. The mean age at operation was 29.9 ± 15.1; 19 (79%) patients were older than 18. Sixteen (67%) patients had arterial hypertension, 5 (21%) patients had bicuspid aortic valve, 4 (17%) patients had descending aneurysm, 2 (8%) patients h

OBJECTIVES: We compared the clinical outcomes between tricuspid valve detachment (TVD) and non-TVD for ventricular septal defect (VSD) closure in infants <5 kg. METHODS: From January 2004 to April 2020, 462 infants <5 kg with VSD without more complex intracardiac lesions and who had undergone VSD closure through the trans-atrial approach were enrolled. Propensity score-matching analysis was performed. Clinical outcomes were compared between the paired TVD group (group D) and paired non-TVD group

Software is completely exposed to an attacker after it is distributed because reverse engineering is widely known. To protect software, techniques against reverse engineering are necessary. A code encryption scheme is one of the techniques. A code encryption scheme encrypts the binary executable code. Key management is the most important part of the code encryption scheme. However, previous schemes had problems with key management. In an effort to solve these problems in this paper, we survey th

Abstract Network reprogramming is a process used to update program codes of sensor nodes that are already deployed. To deal with potentially unstable link conditions of wireless sensor networks, the epidemic approach based on 3‐way advertise‐request‐data handshaking is preferred for network reprogramming. Existing epidemic protocols, however, require a long completion period and high traffic overhead in high‐density networks, mainly due to the hidden terminal problem. In this paper, we address t

From 1989 to 2013, 44 patients (15 neonates) underwent pacemaker implantation within the first year of life. The mean age and weight were 101.2 ± 97.2 days and 4.8 ± 1.8kg at the time of pacemaker implantation. The Indication for pacemaker implantation were postoperative atrioventricular block in 23, congenital atrioventricular block in 16, sinus node dysfunction in 4, and myocarditis induced atrioventricular block in 1. Unipolar epicardial leads (non steroid eluting: 22, steroid eluting: 22) we