• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권12호
• /
• pp.3943-3959
• /
• 2022

People are constantly exposed to stress and anxiety environment, which could contribute to a variety of psychological and physical health problems. Therefore, it is particularly important to identify psychological stress in time and to find a feasible and universal method of stress reduction. This research investigated the influence of different music, such as relaxation music and natural rhythm music, on stress relief based on Electroencephalogram signals. Mental arithmetic test was implemented to create a stressful environment. 23 participants performed the mental arithmetic test with and without music respectively, while their Electroencephalogram signal was recorded. The effect of music on stress relief was verified through stress test questionnaires, including Trait Anxiety Inventory (STAI-6) and Self-Stress Assessment. There was a significant change in the stress test questionnaire values with and without music according to paired t-test (p<0.01). Furthermore, a model based on Transformer for stress level classification from Electroencephalogram signal was proposed. Experimental results showed that the method of listening to relaxation music and natural rhythm music achieved the effect of reducing psychological stress and the proposed model yielded a promising accuracy in classifying the Electroencephalogram signal of mental stress.

• 비파괴검사학회지
• /
• 제30권4호
• /
• pp.330-337
• /
• 2010

본 논문은 원전 증기발생기(SG, steam generator) 세관의 정밀 진단을 위한 차세대 탐촉자인 배열형 와전류 탐촉자의 특성 해석에 대한 3차원 전자기 수치해석을 수행하였다. 다양한 결함 해석을 위해 ASME(American Society of Mechanical Engineers) 표준시험편과 X-probe combo 표준보정시험편(inline EXP/spiral groove combo standard)을 선정하여 탐상신호를 획득하고, 실제 실험 신호와 비교하여 결과의 타당성을 검증하였다. 표준 보정 시험편의 해석 결과를 바탕으로 원전 SG 세관에서 주로 발생하고 있는 pitting, SCC(stress corrosion cracking), multiple SCC, wear 결함에 대하여 탐상신호를 획득하였다. 해석 대상으로는 원자력발전소 SG 세관으로 사용하고 있는 Inconel 600 도체관을 사용하였고, 이때의 시험주파수는 300 kHz이다. 본 논문을 통하여 각각의 결함에 대한 신호 특성을 파악하여 배열형 와전류 탐촉자의 결함의 종류에 따른 신호 특성을 확인할 수 있었다. 본 논문의 결과는 배열형 와전류 탐촉자의 와전류 탐상 신호 평가시 도움이 될 것이다.

• 감성과학
• /
• 제21권1호
• /
• pp.71-82
• /
• 2018

본 연구에서는 스트레스에 대한 심리 반응 요인과 인지 스트레스원에 의해 유발된 심박변이도의 변화와의 관계를 확인하고자 하였다. 33명의 실험참여자는 지난 2주 동안 경험한 스트레스에 대하여 정신적 신체적 증상들을 스트레스 반응 척도 상에 평가하였다. 또한 실험참여자가 인지 스트레스 과제를 수행하는 동안 심전도 신호가 기록되었다. 심박변이도 지표로서, R-R간격의 표준편차(SDNN), 연속한 R-R 간격 차이 값의 평균제곱근(RMSSD)과 심박변이도의 저주파 성분(LF)과 고주파 성분(HF)의 비율이 추출되었다. 스트레스 반응은 회복기 동안의 평균에서 기저선의 평균을 뺀 차이값으로 분석에 사용되었다. 분석 결과, 스트레스 요인과 심박변이도 지표들과의 유의한 정적 상관을 보였다. 특히 스트레스에 대한 공격 반응의 증가는 모든 심박변이도 지표의 증가와 연관이 있었다. 모든 심박변이도 지표의 증가는 자율신경계가 동시에 활성화됨을 의미한다. 즉, 공격 반응의 증가는 교감 및 부교감신경계의 활성도의 증가와 관련이 있다. 또한 긴장, 우울, 피로와 좌절은 RMSSD와의 정적 상관이 있었다. RMSSD의 증가는 부교감신경계 활성의 증가를 의미하는 것으로, 긴장, 우울, 피로, 좌절의 증가와 부교감 신경의 활성도의 증가가 연관이 있었다. 이러한 자율신경의 공동 활성화는 주의 집중을 요하는 인지 스트레스원에 대한 통합된 반응으로 여겨진다.

• BMB Reports
• /
• 제38권4호
• /
• pp.432-439
• /
• 2005

$Ca^{2+}$/calmodulin transduction pathways have been implicated in mediating stress response and tolerance in plants. Here, three genes encoding calmodulin (Cam) members of the EF-hand family of $Ca^{2+}$-binding proteins were identified from Oryza sativa L. databases. Complementary DNA for each of the calmodulin genes, OsCam1, OsCam2, and OsCam3 were sequenced. OsCam1 and OsCam2 encode a conventional 148-amino acid calmodulin protein that contains four characteristic $Ca^{2+}$-binding motifs. OsCam3 encode a similar protein with a 38-amino-acid extension containing a putative prenylation site (CVIL) at the carboxyl terminus. RT-PCR showed that each of the genes is expressed in leaves and roots of 2-week old rice seedlings. By RNA gel blot analysis, OsCam1 mRNA levels strongly increased in response to NaCl, mannitol and wounding treatments. In contrast, OsCam2 mRNA levels were relatively unchanged under all conditions investigated. NaCl treatment and wounding also increased the OsCam3 mRNA level, but in a more transient manner. Our results indicate that although the expression of genes encoding different calmodulin isoforms is ubiquitous, they are differentially regulated by various stress signals. In addition, we have demonstrated that the calcium-channel blocker lanthanum chloride inhibited the induction of OsCam1 gene expression by both NaCl and mannitol treatments. These results suggest that osmotic stress induced expression of OsCam1 gene requires the $[Ca^{2+}]_{cyt}$ elevation that is known to occur in response to these stimuli.

• 한국음향학회지
• /
• 제41권5호
• /
• pp.518-524
• /
• 2022

본 논문에서는 합성곱 신경망과 주의집중 메커니즘을 결합하여 뇌파 신호로부터 감정적 스트레스 인식 성능을 향상시키는 방식을 제안한다. 제안하는 방식에서는 뇌파 신호를 5개의 주파수 영역으로 분해하고, 각 주파수 영역에 합성곱 신경망 계층을 사용하여 뇌파 특징의 공간정보를 획득한 후에 게이트 트랜스포머를 이용한 주의집중 메커니즘을 사용하여 각 주파수 대역에서 두드러진 주파수 정보를 학습하고, 주파수 간 대역 매핑을 통해 보완 주파수 정보를 학습하여 최종 주의집중 표현에 반영한다. DEAP 데이터세트와 6명의 피 실험자가 참여한 뇌파 스트레스 인식 실험을 통해, 제안된 방식이 기존 방식과 비교하여 뇌파 기반 스트레스 인식 성능 향상에 효과가 있음을 보여준다.

• Computers and Concrete
• /
• 제29권1호
• /
• pp.47-57
• /
• 2022

The increase in waste tires has brought serious environmental problems. Using waste tires rubber particles as aggregate in concrete can reduce pollution and decrease the usage of natural aggregate. The paper describes an investigation on flexural bearing capacity of self-compacting concrete (SCC) pavement slabs containing crumb rubber. Cyclic loading tests with different stress ratios and loading frequencies are carried out on SCC pavement slabs containing crumb rubber. Based on Paris Law and test data, the fatigue life of SCC pavement slab containing crumb rubber is discussed, and a revised mathematical model is established to predict the fatigue life of SCC pavement slab containing crumb rubber. The model applies to different stress ratios and loading frequencies. The fatigue life of SCC pavement slab containing crumb rubber is affected by the stress ratio and loading frequency. The fatigue life increases with the increase of stress ratio and loading frequency. Real-time acoustic emission (AE) signals in the SCC pavement slab containing crumb rubber under cyclic loading are measured, and the characteristics of crack propagation in the SCC pavement slab containing crumb rubber under different stress ratios and loading frequencies are compared. The AE signals provide abundant information of fracture process zone and crack propagation. The variation of AE ringing count, energy and b-value show that the fracture process of SCC pavement slab containing crumb rubber is divided into three stages.

• Geomechanics and Engineering
• /
• 제18권5호
• /
• pp.481-492
• /
• 2019

Due to the underground openings, the tangentially concentrated stress of the tunnel remains larger at excavation boundary and decreases toward the interior of the surrounding rock with a certain gradient. In order to study the effect of different gradient stress on rockburst, the true-triaxial gradient and hydraulic-pneumatic combined test apparatus were carried out to simulate the rockburst processes. Under the different gradient stress conditions, the rock-like specimen (gypsum) was tested independently through three principal stress directions loading--fast unloading of single surface--top gradient and hydraulic-pneumatic combined loading, which systematically analyzed the macro-mesoscopic damage phenomena, force characteristics and acoustic emission (AE) signals of the specimen during rockburst. The experimental results indicated that the rockburst test under the gradient and hydraulic-pneumatic combined loading conditions could perfectly reflect the rockburst processes and their stress characteristics; Relatively high stress loading could cause specimen failure, but could not determine its mode. The rockburst under the action of gradient stress suggested that the failure mode of specimen mainly depended on the stress gradient. When the stress gradient was lower, progressive and static spalling failure occured and the rockburst grades were relatively slight. On the other hand, shear fractures occurred in rockbursts accounted for increasingly large proportion as the stress gradient increased and the rockburst occurred more intensely and suddenly, the progressive failure process became unconspicuous, and the rockburst grades were moderate or even stronger.

• 한국산업경영시스템학회:학술대회논문집
• /
• 한국산업경영시스템학회 2002년도 춘계학술대회
• /
• pp.273-278
• /
• 2002

Modern society is an interaction between many different environments. It is important to the mutual relationships between people and especially between people and the environment. One of the mutual relationships between people and the environment is the traffic system, especially the traffic signals which give priority to pedestrian and traffic flow. Traffic signals for the pedestrian on the crosswalk contribute to a safe road environment for the pedestrian, while the traffic signals for the pedestrian running for the flickering of the green signal causes psychological stress. Therefore, this study investigated whether the walking velocity was influenced by the flickering of the green signal or not. Also, this study investigated whether the walking distance had an effect on the walking velocity of the elderly pedestrian or not. It was proved that the flickering of the green signal and the walking distance influenced the walking velocity and subjective sensitiveness according to the result of this study.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 추계학술발표대회 논문집
• /
• pp.128-133
• /
• 2000

The objective of this research is to develop real-time failure detection techniques for damage assessment of composite materials using optical fiber sensors. Signals from matrix cracking or fiber fracture in composite laminates are treated by signal processing unit in real-time. This paper describes the implementation of time-frequency analysis such as the Short Time Fourier Transform(STFT) to determine the time of occurrence of failure. In order to verify the performance of the optical fiber sensor for stress wave detection, we performed pencil break test with EFPI sensor and compared it with that of PZT. The EFPI sensor was embedded in composite beam to sense the failure signals and a tensile test was performed. The signals of the fiber optic sensor when damage occurred were characterized using STFT and wavelet transform. Failure detection system detected the moment of failure accurately and showed good sensitivity with the infinitesimal failure signal.

• Nuclear Engineering and Technology
• /
• 제50권3호
• /
• pp.526-530
• /
• 2018

Human fingernails were used to estimate the radiation dose via electron paramagnetic resonance measurements of radiation-induced radicals. The limiting factors in this research were mechanically induced electron paramagnetic resonance signals due to the mechanical stress during the preparation of the samples. Therefore, different treatment methods of fingernails were used to reduce the mechanically induced signals. The results demonstrate that the mechanically induced and radiation-induced signals have apparently different microwave power saturation behaviors. In addition, the mechanically induced signal shows a fading evolution over time and reaches a constant value. Chemical treatment using the different reagents showed that the minimum mechanically induced signal was obtained using the dithiothreitol reagent. The dose-response curves of the samples treated with dithiothreitol for 30 minutes demonstrated a greater linearity than those of samples treated for 5 minutes. Therefore, to find an unknown absorbed dose in a fingernail sample using a calibration curve, we recommend adopting the mentioned chemical treatment procedure to reduce the uncertainty.