• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.393-402
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• 2012

In this study, we propose a signal processing algorithm to measure the arousal level of a human subject using a PPG(Photoplethysmography) sensor. From the measured PPG signals, the arousal level is determined by PPI(Pulse to Pulse Interval) and discrete-time signal processing. We ran psychophysical experiments displaying visual stimuli on TV display while measuring PPG signal from a finger, where the nature landscape scenes were used for restorative effect, and the urban environments were used to stimulate the stress. However, the measured PPG signals may include noise due to subject movement and measurement error, which results in incorrect detections. In this paper, to mitigate the noise impact on stimulus detection, we propose a detecting algorithm using digital signal processing methods and statistics of measured signals. A filter is adopted to remove a high frequency noise and adaptively designed taking into account the statistics of the measured PPG signals. Moreover we employ a hysteresis method to reduce the distortion of PPI in decision of emotional. Via experiment, we show that the proposed scheme reduces signal noise and improves stimulus detection.

• Science of Emotion and Sensibility
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• v.17 no.2
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• pp.85-90
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• 2014

The purpose of the study is to develop self-management system that people can enhance physical and psychological health through repeating by themselves to relieve work-related stress. The regular respiration can help homeostasis of heart to maintain. Also the effect can be stabilized from irregular heart rhythm by work-related stress. People have optimal respiration cycle to stabilize heart rhythm and repeat training using their RSP(respiration) time including expiration and inhalation. This system is not only offering optimal respiration training service but also finding optimal respiration cycle. The adults who have stress from work participated in verification experiment. This study expects to help those people who are workers related to call center jobs in emotional labor can relieve their stress. It can also help to enhance their own health and increase their work efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1191-1198
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• 2011

The use of a ventricular assist device (VAD) can raise the one-year survival rate without cardiac transplantation from 25% to 52%. However, malfunction of the VAD system causes 6% of VAD patients' deaths, which could possibly be avoided through the development of new VADs in which VAD malfunctions do not affect the patient's heart movement or hemodynamic state. A conventional VAD has an impeller or vane for propelling blood that can allow blood to regurgitate when the propelling force is weaker than the aortic pressure. In this paper, we developed a new pulsatile conduit-shaped VAD that has two valves. This device removes the possibility of blood regurgitation and has a small stationary area even when the pumping force is extremely weak. We estimated the characteristics of the device by measuring the outflow and the pressure of the pump in in-vitro and in-vivo experiments.

• Journal of the korean veterinary medical association
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• v.43 no.9
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• pp.825-832
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• 2007

모든 부정맥이 치료를 필요로 하는 것은 아니지만, 다양한 부정맥들이 허약 (weakness), 실신 (syncope)을 유발하거나 울혈성 심부전을 악화시키며 일부의 부정맥들은 치명적인 심장 이상을 일으킨다. 일반적으로 임상증상을 유발하는 부정맥들과 급사의 지표가 될 수 있는 부정맥들은 치료한다. 불행하게도, 수의학 분야의 심장전문의들 사이에서 어떤 부정맥들을 치료해야만 하고 어떻게 관리하는 것이 최선인가에 관한 내용이 명확하게 일치하고 있지는 않다. 사실은 어떤 항부정맥 약물을 우선적으로 선택해야 하는가에 관해서 명확한 합의점이 없을 뿐만 아니라 어떤 범주의 약물이 효과적인가에 대해서도 논란의 여자기 있다. 예를 들어, 심각한 심실성 부정맥이 성공적으로 치료되지 않으면 현저한 이소성 박동(ectopy)이 지속적으로 남을 수도 있다. 또한 만일 임상증상들 (실신 등)이 해소되고 지속적인 심실성 부정맥이 잘 통제된 이러한 류의 질문들에 대한 대답은 대부분 명확하지 않고 신중하게 숙고한 의견에 불과할 수도 있다.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.193-196
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• 2002

완전인공심장은 크게 정상류형과 박동류형이 있다. 정상류형 인공심장중 축류형 혈액펌프는 기구가 간단하고 비용적형이기 때문에 소형화가 가능한 장점이 있지만, 가동중 발생하는 난류로 인해 용혈현상이 따른다는 단점이 있다. 이 용혈의 형성과정은 실제와 가까운 모의실험을 하지 않고서는 알 수가 없다. 따라서 본 연구에서는 모의 실험단계를 거치지 않고 유한요소해석에 의한 난류평가를 통하여 용혈지수가 가장 낮은 임펠러의 형상을 연구하였다. 난류해석 결과, vane매수가 적을 경우 상대적으로 용혈지수가 낮게 나타나는 것을 알 수 있었으나 vane매수가 적을 경우에는 일정한 출구유량을 얻기 위해 임펠러의 고속회전 이 필요하며 이에 따른 난류에너지가 발생, 높은 용혈지수가 예상되므로 본 논문에서는 vane매수 4매-6매 중 6000-7000rpm의 회전속도사이의 조건으로 설계된 임펠러의 모델이 적당한 것으로 예측할 수 있었다.

• Neonatal Medicine
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• v.18 no.2
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• pp.395-398
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• 2011

Sick sinus syndrome (SSS) is a disorder characterized by sinus node dysfunction. Although the condition is most common in the elderly, it can occur in children including neonates and its recognition and treatment are important. The diagnosis of SSS is based on the presence of sinus bradycardia, sinus arrest or exit block, combinations of sinoatrial and atrioventricular nodal conduction disturbances, and atrial tachyarrhythmias documented in the Holter recordings. In most children with SSS, previous history of congenital heart malformation or cardiac surgery is noted. SSS is also seen in the children including neonates without heart disease or other contributing factors, however SSS is most often idiopathic. The treatment of SSS depends on the basic rhythm problem, but generally involves the placement of a cardiac pacemaker. We report a case of SSS in extremely low birth weight infant without congenital heart disease and suggest that the treatment system is necessary for preterm infants with SSS.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.1
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• pp.92-97
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• 2009

Low power consumption is crucial for medical implantable devices. A low-power 4th-order band-pass Gm-C filter with distributed gain stage for the sensing stage of the implantable cardiac pacemaker is proposed. For the implementation of large-time constants, a floating-gate operational transconductance amplifier with current division is employed. Experimental results for the filter have shown a SFDR of 50 dB. The power consumption is below $1.8{\mu}W$, the power supply is 1.5 V, and the core area is $2.4\;mm{\times}1.3\;mm$. The filter was fabricated in a 1-poly 4-metal $0.35-{\mu}m$ CMOS process.

• Cartoon and Animation Studies
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• s.5
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• pp.517-524
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• 2001

인간의 내면에 숨어있는 양면성을 주제로 그 양면의 극적인 대조를 이용하여 인간의 고뇌를 그리고, 타이포애니메이션을 이용하고 영상과 사운드의 접목을 통하여 인간내면의 갈등구조를 그리고자 했다. 겉으로는 일상적으로 반복되는 생활이 평화스럽게 보이지만, 인간의 내면에서는 항상 갈등이 존재함을 한 방울씩 떨어지는 반복적인 물방울 소리와 영상, 그리고 다듬이질 소리를 이용해 다들이질 치는 심장박동을 표현함으로써 대신하고자 했으며, 이와 더불어 극적인 타이포애니메이션을 구현하고자 했다. 인간내면의 갈등구조, 화면의 스크레치와 노이즈의 표현으로 이를 더욱 심화하고, 흑과 백, 그리고 맑은 영상과 비트있는 사운드를 통한 평화스러움과 인간내면 갈등구조에서 고뇌하면서도 평화스러워 보이는 한 인간의 속내를 표현하고자 했다. 인간내면의 갈등이 존재함에도 불구하고 평화스러워 보일 만큼 일상에 젖어 인간본연의 가치를 쉽게 잊고 살아갈 수도 있는 인간의 양면성, 급속한 변화를 담고 있는 현대사회 구조에 적응하여 살아가면서 느껴야 하는 무기력, 반복적인 생활, 획일화되는 사람들, 그러면서도 어쩔 수 없이 존재하는 내면의 갈등구조, 이 모든 것을 짧은 영상물에 담기에는 한계가 있으나, 어떤 결론을 만들어 제시하는 것이 아니라 상황의 표현에 중점을 두고 작품을 전개하려 했다.

• Science of Emotion and Sensibility
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• v.26 no.4
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• pp.51-70
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• 2023

This study employed driving simulation to examine how takeover request (TOR) information modalities (visual, auditory, and visual + auditory) in Level-3 automated vehicles, and road types (straight and curved) influence the driver's control takeover time (TOT) and mental workload, assessed through subjective workload and heart rate variations. The findings reveal several key points. First, visual TOR resulted in the quickest TOT, while auditory TOR led to the longest. Second, TOT was considerably slower on curved roads compared to straight roads, with the greatest difference observed under the auditory TOR condition. Third, the auditory TOR condition generally induced lower subjective workload and heart rate variability than the visual or visual + auditory conditions. Finally, significant heart rate changes were predominantly observed in curved road conditions. These outcomes indicate that TOT and mental workload levels in drivers are influenced by both the TOR modality and road geometry. Notably, a faster TOT is associated with increased mental workload.

• Smart Media Journal
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• v.7 no.4
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• pp.90-98
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• 2018

A Multilinear LDA Method of Tensor Representation for ECG Signal Based Individual Identification Electrocardiogram signals, included in the cardiac electrical activity, are often analyzed and used for various purposes such as heart rate measurement, heartbeat rhythm test, heart abnormality diagnosis, emotion recognition and biometrics. The objective of this paper is to perform individual identification operation based on Multilinear Linear Discriminant Analysis (MLDA) with the tensor feature. The MLDA can solve dimensional aspects of classification problems in high-dimensional tensor, and correlated subspaces can be used to distinguish between different classes. In order to evaluate the performance, we used MPhysionet's MIT-BIH database. The experimental results on this database showed that the individual identification by MLDA outperformed that by PCA and LDA.