• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.75-78
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• 2009

본 연구에서는 세 가지의 각성상태(긴장, 중립, 이완감정)가 3-back 과제 수행능력에 어떠한 영향을 미치는지 관찰하고자 한다. 10명의 남자 (평균 $25.7{\pm}1.5$ 세) 대학생과 10명의 여자 (평균 $24.5{\pm}1.8$ 세) 대학생이 본 실험에 참여하였다. 집단 검사를 통해 추출된 사진을 이용하여 긴장, 중립, 이완의 세 종류의 각성상태를 유발하여 3-back 과제 수행 능력 측정 실험을 수행하였다. Rest 1 (2분), 감성유발사진제시 1 (2분), 3-back Task 1 (2분), 감성유발사진제시 2 (2분), 3-back Task2 (2분), Rest2 (2분)의 5단계로 실험이 진행되었다. 또한 제시된 감정 사진으로 적절한 arousal level 이 유발되었는지를 확인하기 위해 GSR 신호를 측정하였고, 실험 종료 후 주관적 평가를 실시하였다. 3-back 과제의 정답률은 중립감정일 때 가장 컸고, 이완, 긴장 감정 순서였다. 또한 통계적으로 유의하지는 않았지만 중립감정일 때 반응시간이 가장 빠른 경향을 보였다. 본 연구결과로부터 인지 처리와 무관하게 유발된 각성의 증가나 감소는 과제 수행능력을 감소시킬 수 있다는 사실을 유추할 수 있다.

• Science of Emotion and Sensibility
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• v.12 no.4
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• pp.373-380
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• 2009

This study tried to investigate how three levels of arousal affect performance of a 3-back task. Ten university male (age $25.7{\pm}1.5$) and ten female (age $24.5{\pm}1.8$) students participated in this experiment. Using pictures selected from a group test, three levels of arousal, i.e. tensed, neutral, and relaxed emotions, were induced. Each subject was run through the procedure three times, once for each arousal level. The procedure consisted of six phases for each arousal condition Rest 1(2 min), Picture 1(presenting emotion arousing photos for 2 min), 3-back task 1(2 min), Picture 2(presenting emotion arousing photos for 2 min), 3-back task 2(2 min), and Rest 2(2 min). Skin conductance level(SCL) of electrothermal activity was also measured during all phases of the experiment. The accuracy rate of 3-back task performance was the highest at a neutral emotional state, followed by relaxed and then tensed emotional state. There was no difference in reaction time(RT) among the three levels of arousal. SCL was the highest at a tensed emotional state, followed by neutral emotional state and then relaxed emotional state. Based on the results, it could be inferred that tension, induced by stimuli unrelated to cognitive tasks, decreases the ability to perform cognitive tasks.

• Korean Journal of Cognitive Science
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• v.16 no.3
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• pp.189-197
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• 2005

In this study, changes in performance of 2-back task, blood oxygen saturation and heart rate due to $40\%$ concentration oxygen supply were observed. Five male $(25.8\pm1.3)$ and five female $(23.0\pm1.0)$ college students were nked to perform 2-bark task during two types of oxygen (concentration $21\%,\;40\%$) administration. The experimental sequence consisted of Rest1(1 min.), 0-back Task (1 min.), 2-bark Task (2 min.), and Rest2 (4 min.) and the physiological signals such as blood oxygen saturation and heart rate were measured throughout the stages. The experimental result showed that the performance increased significantly at $40\%'s$ concentration of oxygen rather than $21\%'s$, which shows oxygen supply has positive influence on cognitive performance. When $40\%$ concentration oxygen is supplied, the oxygen saturation in the blood increased and heart rate was decreased significantly comparing to $21\%$. It is Suggested that $40\%$ oxygen can stimulate brain activation bY increasing actual blood oxygen concentration in the process of cognitive performance, and hyperoxia makes heart rate decrease.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2012.05a
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• pp.105-106
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• 2012

• Korean Journal of Cognitive Science
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• v.29 no.1
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• pp.39-59
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• 2018

To elucidate the effect of working memory (WM) load on negative facial emotion processing, we examined ERP components (P1 and N170) elicited by fearful and neutral expressions each of which was presented during 0-back (low-WM load) or 2-back (high-WM load) tasks. During N-back tasks, visual objects were presented one by one as targets and each of facial expressions was presented as a passively observed stimulus during intervals between targets. Behavioral results showed more accurate and fast responses at low-WM load condition compared to high-WM load condition. Analysis of mean amplitudes of P1 on the occipital region showed significant WM load effect (high-WM load > low-WM load) but showed nonsignificant facial emotion effect. Analysis of mean amplitudes of N170 on the posterior occipito-temporal region showed significant overall facial emotion effect (fearful > neutral), but, in detail, significant facial emotion effect was observed only at low-WM load condition on the left hemisphere, but was observed at high-WM load condition as well as low-WM load condition on the right hemisphere. To summarize, facial emotion effect observed by N170 amplitudes was modulated by WM load only on the left hemisphere. These results show that early emotional processing of negative facial expression could be eliminated or reduced by high load of WM on the left hemisphere, but could not be eliminated by high load on the right hemisphere, and suggest right hemispheric lateralization of negative facial emotion processing.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.438-439
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• 2018

본 논문은 (주)효성 중공업연구소에서 국책과제를 통해 자체 개발한 MMC(Modular Multi-level Converter) type ${\pm}12kV$ 25MVA HVDC 시스템의 시험결과에 대해 소개한다. 제주에 구축된 HVDC 실증단지는 국내 유일의 MMC type 전압형 HVDC 시스템이며 11-레벨의 AC 출력 전압을 형성하는 2개의 컨버터가 Back-to-Back 형태로 구성되어 있다. 각 컨버터의 AC 출력단은 각각 계통과 풍력발전단지에 연계되어 풍력발전단지에서 생산된 전력을 계통으로 전송하는 역할을 한다. 본 논문에서는 국책과제의 정량적 목표항목을 달성하기 위한 시험을 수행한 결과에 대해서 소개한다.

• Korean Journal of Cognitive Science
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• v.22 no.4
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• pp.405-427
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• 2011

We explored whether unconscious thought affects the processing of scientific technology information concerning nuclear power. Instead of conscious deliberation of cost-benefit analysis of nuclear energy, we would like to show the effects of unconscious thought on decision making. Participants were presented with all information about nuclear power and then judged the most positive as well as the most negative items. Participants in the unconscious thought condition performed a 2-back digit memory task as distractor before they made any decision regarding the nuclear power. Those in conscious thought condition were asked to carefully evaluate all presented information while participants in the immediate decision condition made a quick decision. Based on the analysis of previous studies on this topic, we attempted to obtain the potential effects of unconscious thought by modifying materials and experimental procedures including the use of noise. Even with these new manipulations, the effect of unconscious thought on decision making was not observed in Experiment 1. In contrast, we observed a significant effect of unconscious thought on decision making when task purpose was clearly presented after participants have finished reading all information regarding nuclear power. The results of the present study indicate that if the task purpose were clearly presented, the effects of unconscious thoughts on decision making could be observed.

• Korean Journal of Schizophrenia Research
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• v.15 no.2
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• pp.66-72
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• 2012

Objectives : The aim of this study was to investigate whether verbal and spatial working memory functions were impaired not only in patients with schizophrenia but also in people at ultra-high risk for first-episode psychosis. Methods : Twenty-five patients (M 13, F 12) with schizophrenia (SPR), 21 people at ultra-high risk for psychosis (UHR)(M 10, F 11) and 19 normal controls (NC)(M 10, F 9) were recruited. The working memory was assessed by using the verbal and spatial n-back test. The working memory load increased incrementally from the 0-back to the 3-back condition. Results : SPR performed significantly lower than NC and UHR in terms of hit rates of verbal and spatial n-back test. UHR subjects conducted significantly lower than NC and higher in trend-level than SPR in terms of hit rates of verbal and spatial n-back test. These differences were derived from the high working memory load (2-back and 3-back), not from the low working memory load (0-back and 1-back). There was no significant difference between the verbal and spatial n-back test across the three groups. Conclusion : These findings suggest that verbal and spatial working memory dysfunction may be general rather than differential in terms of stimuli modality, and this working memory deficit may be an important trait factor in schizophrenia.

• Korean Journal of Applied Biomechanics
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• v.18 no.2
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• pp.49-58
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• 2008

The purpose of this study was to identify effects of walking speed and a cognitive task during treadmill walking on gait variability. Experiments consisted of 5 different walking speeds(80%, 90%, 100%, 110% and 120% of preferred walking speed) with/without a cognitive task. 3D motion analysis system was used to measure subject's kinematic data. Temporal/spatial variables were selected for this study; stride time, stance time, swing time, step time, double support time, stride length, step length and step width. Two parameters were used to compare stride-to-stride variability with/without cognitive task. One is the coefficient of variance which is used to describe the amount of variability. The other is the detrended fluctuation analysis which is used to infer self-similarity from fluctuation of aspects. Results showed that cognitive task may influence stride-to-stride variability during treadmill walking. Further study is necessary to clarify this result.

• Therapeutic Science for Rehabilitation
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• v.8 no.1
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• pp.41-50
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• 2019

Objective: The purpose of this study was to investigate whether there is a difference in the brain connectivity in mental practice and physical performance of training bilateral upper extremity function. Method: The subject performed activities involving mental tasks and physical exercise for bilateral upper extremity functioning during each phase of EEG measurements. The subject performed a symmetrical task(lifting a box and placing it back) that involved moving both arms at the same time and an asymmetrical task(opening and closing a bottle cap) in order to perform functional tasks. EEG electrodes were attached to Fp1, Fp2, F3, F4, T3, T4, P3, and P4. Data analysis was performed using Cross-Line Mapping for correlational analyses between EEG electrode pairs. Conclusion: This study found that the brain connectivity patterns of symmetrical and asymmetric upper extremity tasks have similar patterns for the motor and sensory area, and that the correlation of the physical practice is generally higher than that of the mental practice.