• Journal of Families and Better Life
• /
• v.19 no.2
• /
• pp.143-152
• /
• 2001

The purpose of this study was to investigate the effects of family stress on work stress and to examine the effects of family and work stress on psychological wellbeing in employed men and women. The analyses of the present study were based on a sample of 263 full-time employed men and 258 full-time employed women aged 30-49 in dual-earner families. There were significant gender differences in marital stress, parenting stress and psychological well-being with women reporting higher levels of stress. However, employed men and women experienced similar levels of work stress. The results from regression analyses showed that stress in the family domain contributed significantly to work stress. Both marital stress and parenting stress were significantly related to higher levels of work stress fro employed men and women. The findings of this study indicated that higher levels of marital stress and work stress were predictive of psychological well-being for men and women in dual-earner couples. Among employed women, marital stress and work stress were more highly related to psychological well-being than among employed men.

• Korea-Australia Rheology Journal
• /
• v.15 no.2
• /
• pp.97-105
• /
• 2003

In the previous paper (Hyun et al.,2002), we have investigated the shape of storage modulus (G') and loss modulus (G") of complex fluids under large amplitude oscillatory shear (LAOS) flow. As the strain amplitude increases, owever, the stress curve becomes distorted and some important information may be smothered during data processing. Thus we need to investigate the stress data more precisely and systematically. In this work, we have obtained the stress data using high performance ADC (analog digital converting) card, and investigated the nonlinear response of complex fluids, 4wt% xanthan gum (XG), 2 wt% PVA/ 1 wt% Borax, and 1 wt% hyaluronic acid (HA) solutions, using Fourier transformation (FT) rheology. Comparing the strain signals in time domain with FT parameters in frequency domain, we could illustrate the sensitivity and importance of FT rheology. Diverse and unique stress patterns were observed depending on the material system as well as flow environment. It was found that they are not the outcome of experimental deficiency like wall slip but characteristics of the material system. When nonlinear response of complex fluids is analyzed, the intensity and phase angle of higher harmonic contributions should be considered together, and the shape of the stress signal was found to be strongly dependent upon phase angle.ngle.

• Structural Engineering and Mechanics
• /
• v.28 no.4
• /
• pp.387-410
• /
• 2008

The fatigue damage accumulation rates of horizontally curved thin walled box-girder bridge have been estimated from vehicle-induced dynamic stress history using rain flow cycle counting method in the time domain approach. The curved box-girder bridge has been numerically modeled using computationally efficient thin walled box-beam finite elements, which take into account the important structural actions like torsional warping, distortion and distortional warping in addition to the conventional displacement and rotational degrees of freedom. Vehicle model includes heave-pitch-roll degrees of freedom with longitudinal and transverse input to the wheels. The bridge deck unevenness, which is taken as inputs to the vehicle wheels, has been assumed to be a realization of homogeneous random process specified by a power spectral density (PSD) function. The linear damage accumulation theory has been applied to calculate fatigue life. The fatigue life estimated by cycle counting method in time domain has been compared with those found by estimating the PSD of response in frequency domain. The frequency domain method uses an analytical expression involving spectral moment characteristics of stress process. The effects of some of the important parameters on fatigue life of the curved box bridge have been studied.

• Journal of the Korea Concrete Institute
• /
• v.18 no.5 s.95
• /
• pp.695-702
• /
• 2006

The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

• The Korean Journal of Emergency Medical Services
• /
• v.13 no.2
• /
• pp.61-72
• /
• 2009

Purpose : This study aimed to analyze the posttraumatic stress research trends in Korean and foreign firefighters. Method : Total 63 published international articles were searched by Pub Med internet site and total 17 published Korean articles were searched by Korean Medical Database internet site using 'PTSD in firefighters'. These articles were analyzed by published time, domains of journal, research designs, key words and research subjects. Result : 1) By the published time, there were 29 disaster-related researches(46.0%) and 34 job-related researches(54.0%) among 63 international articles. However, there were 16 disaster-related researches(94.1%) and 1 job-related research (5.9%) of Korean 17 articles. 2) By the international research domain, 9 researches(14.3%) were published in The Journal of Nervous and Mental Disease. Among domestic research domain, there were 9 researches(52.9%) consisting of 6 master's degrees and 3 doctor degrees. In major analysis of Korean domain, the highest portion is 4 psychology researches. (23.5%) 3) In the term of the international research design, quantitative research methods were highly used in both 23 disaster-related researches (36.5%) and 30 job-related researches(47.5%). In domestic research, quantitative research methods were mostly used in 14 job-related researches(82.3%) and Q methodology was only used in 1 disaster-related research(5.9%). 4) Looking on the research content trends according to the key words, 9 researches (31.0%) done on posttraumatic stress and coping had the most research and was followed up by posttraumatic stress symptom. Among these researches, key words for PTSD(Posttraumatic Stress Disorder) and PTS(Posttraumatic Stress) were mostly used. Moreover, there was 1 domestic study done on verifying the trends of Posttraumatic Stress in disaster-related research with PTS as the key word. In job-related research, the relationship between the Posttraumatic Stress and other factors had the most with ten studies (62.5%). Among these researches, key words for 5 PTSD(31.3%) were mostly used. 5) According to the international research subjects, the Posttrau consist the most subjects with 16 cases each for disaster and job related stress ; however, domestic research had 16 studies(94.1%) only using firefighters and 1 (5.9%) with their families as subjects. Conclusion : Although the studies of Posttraumatic Stress on Korean firefighters had started later than those on Foreign firefighters, first used for crucial topics show research development in various fields of study and should be tested for studies like those done in abroad regarding multiple topics and methods.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.2
• /
• pp.17-23
• /
• 2011

In this paper, daily life stress monitoring system is proposed. The proposed wireless ECG module, reducing the noise and increasing the size of signal, amplification circuit was designed for. Using HRV(Heart Rate Variability), extracted by measuring R-wave, stress diagnostic algorithms to assess the stress of human emotion were developed. For monitoring the activities, the proposed system is consist of small rectangular size for portable and by simple measurement it is possible to measure at any time. Through experiments, the proposed approach to represent user's stress level can be confirmed. Through that, it can see appropriate structure to obtain R-wave for stress assess as well as high resemblance to the clinical electrocardiogram. In this paper, performed experiments was developed nonrestraint measuring and wearable wireless biometric scanner that is able to monitor the heart's electrical activity of everyday life.Using this, the algorithm system, that is able to assess stress index through time-domain and frequency-domain analysis of the front and the rear of performing stress load protocol, was developed,

• Journal of Korean Traditional Oncology
• /
• v.16 no.1
• /
• pp.15-31
• /
• 2011

Objective : The study aims to investigate the effect of moxibustion treatments on autonomic nervous system function of cancer patients through the evaluation of heart rate variability (HRV) biofeedback testing. Materials and Methods : Six cancer patients from inpatient care unit of Dunsan Oriental Hospital, Daejeon University were given three moxibustion treatment sessions every other day over one week period on five Oriental Medicine meridian points CV4, CV6, CV12, KD1, and PC8. HRV biofeedback was conducted before and after each treatment sessions. Three areas of analyses were done from the test conducted; Time Domain Analysis, Frequency Domain Analysis and Autonomic Nervous System (ANS) balance analysis. Results : Time Domain Analysis has shown increased Standard Deviation of all Normal R-R Intervals (SDNN), and decreased Mean Heart Rate and Physical Stress Index (PSI) levels, with statistical significance (P<0.05). In Frequency Domain Analysis, series of moxa treatments have increased Total Power (TP), Very Low Frequency Oscillation Power (VLF), High Frequency Oscillation Power (HF), normalized HF values while decreasing Low Frequency Oscillation Power (LF), normalized LF and LF/HF ratio with statistical significance (P<0.05). The values of ANS activity, ANS balance, Stress resistance, Stress index, have also shown significant changes. For cardiac stability stroke volume power (SP) and Blood Vessel Tension (BVT) were followed, which were both increased after treatment. All changes were statistically significant (P<0.05). Conclusion : The results have shown a positive correlation between the moxibustion treatments and autonomic nervous system responses on cancer patients through the HRV biofeedback testing. This study suggests possible application of moxibustion treatments for managing ANS functions of cancer patients, although additional studies with larger population are necessary to confirm the data.

• International Journal of Highway Engineering
• /
• v.9 no.2 s.32
• /
• pp.63-76
• /
• 2007

The transformed field domain analysis method was developed in this study to investigate the aspects of the stress distribution in overlaid concrete pavement systems under multi-axle vehicle loads. The overlay was assumed to be perfectly bonded or perfectly unbonded to the existing concrete pavement. The loads considered included the dual tired single-axle, tandem-axle, and tridem-axle loads, and the effects of the overlay's thickness, elastic modulus, and Poisson's ratio on the stress distribution were investigated. Details of the analysis method in the transformed field domain to analyze the overlaid pavement was described in this paper and the analysis results were verified by comparing with those obtained using the finite element method. From the analysis, it was found that the maximum tensile stress in the existing slab decreased as the overlay's thickness, elastic modulus, and Poisson's ratio increased, and the bonded overlay showed more significant effects than the unbonded one. The overlay's Poisson's ratio did not much affect the stresses, and the features of the maximum stress reduction in the existing slab due to the increase of the thickness, elastic modulus, and Poisson's ratio of the overlay were investigated. The effects of the number of axles on the stress distribution and the maximum stress were also investigated.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.9 no.3
• /
• pp.266-281
• /
• 2017

Hydroelastic interactions of a deformable floating body with random waves are investigated in time domain. Both hydroelastic motion and structural dynamics are solved by expansion of elastic modes and Fourier transform for the random waves. A direct and efficient structural analysis in time domain is developed. In particular, an efficient way of obtaining distributive loads for the hydrodynamic integral terms including convolution integral by using Fubini theory is explained. After confirming correctness of respective loading components, calculations of full distributions of loads in random waves are expedited by reformulating all the body loading terms into distributed forms. The method is validated by extensive convergence tests and comparisons against the counterparts of the frequency-domain analysis. Characteristics of motion/deformation responses and stress resultants are investigated through a parametric study with varying bending rigidity and types of random waves. Relative contributions of componential loads are identified. The consequence of elastic-mode resonance is underscored.

• Journal of the Korean Ceramic Society
• /
• v.47 no.4
• /
• pp.333-337
• /
• 2010

Domain structure and polarization switching in (001)-oriented $Pb(Mg_{1/3}Nb_{2/3})O_3-x%PbTiO_3$ (PMN-x%PT) crystals for x=20 and 35at% have been investigated in-situ by scanning force microscope (SFM) in a piezoresponse mode under a step DC electrical voltage. In the initial annealed condition, polar nano domains (PND) and domain striations oriented along {110} were observed in x=20 and x=35, respectively. For x=20, domain switching occurs by heterogeneous nucleation, where nucleation is not confined in the vicinity of domain boundaries, but rather can occur throughout the crystal volume. However, for x=35, domain switching tends to be preferentially initiated near pre-existing twin boundaries. With increasing the applying voltage, the nuclei density increased and assembled into {110} striations, indicating a stress-accommodated domain growth process. At higher voltage, nucleation occurs heterogeneously throughout the crystal volume.