• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1109-1112
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• 2003

본 연구는 switching mode 의 Power NMOSFET failure mode 에 관하여 분석하고 원인을 규명하였다. 분석된 power NMOSFET은 30V급이며, vender A의 상용화 제품이다. 발생한 failure mode는 power switch 회로에서 특정 ID 를 detect 하지 못하는 mode 였다. 측정결과 source voltage 가 저하되었으며, power NMOSFET DC 동작특성 분석 결과 Vgs 변화에 따라 Id 가 저하되었다. Fail 된 power MOSFET 특성값 reference는 동일 LOT의 양품을 선정하였다. De-cap후 Inversion 과 Accumulation mode 별로 Photoemission spectrum analyzer(PSA) 분석 방법을 적용하였다. 결과 accumulation mode 에서 intensity가 감소하였으며, forward diode mode에서 국소적으로 변화하는 영역이 검출되었다. SEM 분석결과 gate metal 과 source metal 의 micro-contact 이 이루어져 있었다. 이 경우 gate metal 과 source metal 사이 close loop 를 형성하여 gate charge량을 변화시켜 power NMOSFET의 출력을 저하하는 failure mode가 발생됨을 분석할 수 있었다.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1983-1989
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• 2020

The human reliability analysis is a method by which, in general terms, the human impact to the safety and risk of a nuclear power plant operation can be modelled, quantified and analysed. It is an indispensable element of the PSA process within the nuclear industry nowadays. The paper herein presents a sensitivity study of the human reliability analysis performed on a real nuclear power plant-specific probabilistic safety assessment model. The analysis is performed on a pre-selected set of post-initiator operator actions. The purpose of the study is to investigate the impact of these operator actions on the plant risk by altering their corresponding human error probabilities in a wide spectrum. The results direct the fact that the future effort should be focused on maintaining the current human reliability level, i.e. not letting it worsen, rather than improving it.

• Journal of Acupuncture Research
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• v.20 no.4
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• pp.157-169
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• 2003

Objective : The effects of electroacupuncture(EA) stimulation on heart rate variability(HRV) for healthy adults are investigated with power spectrum analysis(PSA) of HRV. Methods : The HRVs of every 10 minute for 22 healthy volunteers(13 men and 9 women) were measured for an hour with SA-3000P(Medicore Co., Ltd., Korea). The median age with arithmetic range of 13 men and 9 women was 26.00 years with 22.75~27.00 years. The initial 20 minutes were defined as baseline period(pre-EA period), the following 20 minutes as the EA period and the last 20 minutes as the post-EA period. In each EA periods, volunteers received EA(2Hz, 0.6~0.8ms duration, maximal tolerated stimulation without discomfort) on the right Zusanli(ST36), Shangjuxu(ST37) acupoints while supine, resting. Results : Heart rate of volunteers at post-EA period was significantly decreased compare to that of pre-EA period, while SDNN at post-EA period was significantly increased. Heart rate at EA period was significantly decreased compare to that of pre-EA period, but Ln(LF) and LF/HF at EA period were significantly increased. Ln(HF) at post-EA period was significantly decreased compare to that of EA period, while the other variables were not significantly changed. Conclusions : The results suggest that EA in healthy adults is associated with changed activity in the sympathetic and parasympathetic nervous system. Further study is needed for investigating the effects of EA on HRV and autonomic nervous system.

• The Journal of Internal Korean Medicine
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• v.25 no.4
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• pp.25-33
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• 2004

Objective : The effects of Indium-Gallium-Aluminium-Phosphide(InGaAlP) laser transcutaneous irradiation on heart rate variability(HRV) in healthy adults are investigated with power spectrum analysis(PSA) of HRV. Methods : The control group consisted of 20 healthy volunteers (10 men, 10 women). The experiment was divided into 5 different periods, the pre-1st laser period(10 minutes), the 1st laser period(30 minutes), the post-1st laser period(5 minutes), the 2nd laser period( 30 minutes) and the post-2nd laser period(30 minutes). HRV was measured for 5 minutes at the pre-1 st laser period, the post-l st laser period and the post-2nd laser period. The laser period is the period in which InGaAlP laser transcutaneous Irradiation treatment occurs. Results : 1. SDNN of volunteers at post-1st laser period and post-2nd laser period significantly increased compared with that of the pre- 1 st laser period. 2, Ln(VLF) at post-I st laser period significantly increased compared with that of pre-1st laser period, while Ln(HF) at post-2nd laser period significantly decreased compared with those of pre- I st laser period and post-1st laser period, 3. Ln(TP) at post-1st laser period and post-2nd laser period significantly increased compared with that of pre-1st laser period, 4, LF/HF Ratio at post-2nd laser period significantly increased compared with those of pre-1st laser period and post-1st laser period. But the other variables did not significantly change. Conclusions : The results suggest that InGaAlp laser transcutaneous Irradiation in healthy adults is associated with the autonomic nervous systems. Further study is needed for investigating the effects of laser irradiation on autonomic nervous systems.

• The Journal of the Society of Stroke on Korean Medicine
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• v.6 no.1
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• pp.9-16
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• 2005

Objective : The heart rate variability is very useful indicator to study the function of the autonomic nervous system(ANS), and the physiologic signals can be observed based on the changes of the ANS of the heart. In order to assay the effects of the laser exposing to healthy subjects, the double blind test has been performed. Methods : This study included 62 healthy adults who have not any ANS disease and had normal sinus rhythm in electrocardiogram. The control group consisted of 31 subjects, laser group consisted of 31 subject. HRV was measured for 5 minutes before laser irradiation, sham and real laser irradiated for 30 minutes and than HRV remeasured for 5 minutes. Statistical significance was evaluated by independent T-test. Results : Mean HRV, Ln(VLF), Ln(HF), Ln(TP) of both groups at post-laser period decreased compared with that of the pre-laser period. Ln(LF) of both groups at post-laser period increased compared with that of the pre-laser period. LF/HF, SDNN of real laser group decreased and sham group decreased. Conclusions : There is no difference between two groups. The reason is presumed that all the studied subjects are healthy adults, and also the short and single transcutaneous laser irradiation would not influence upon changes of the ANS. The further study must be followed.