• 감성과학
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• 제5권1호
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• pp.71-78
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• 2002

자동차의 운전은 지각, 의사결정, 운동능력 등 다양한 능력을 필요로 하는 복잡한 행동의 연속이고, 지속적인 고도의 의식집중이나 외부자극에 대한 긴장감이 유발되므로 운전자는 피로를 느끼게 되며, 이러한 피로는 교통사고의 원인이 되고 있다. 그럼에도 불구하고 복잡한 도시생활, 교통체증, 직업적인 특성 등에 의하여 운전자가 차량 내에서 보내는 시간은 증가하고 있고, 그에 따른 피로나 스트레스를 피할 수 없는 실정이다. 본 연구에서는 산소공급에 의한 운전 중 피로경감의 가능성을 알아 보기 위하여 주관적인 평가 및 반응시간 테스트를 통하여 각각 다른 산소농도를 공급할 때의 주행시간 경과에 따른 운전 피로감을 검토하였다. 그 결과, 주관적 피로감은 저농도(18%)의 산소조건에서 가장 피로를 많이 느끼고 고농도(30%)의 산소조건에서의 피로감은 상대적으로 감소하였다. 졸림감도 1시간 이상 주행시간이 경과된 경우에 고농도 산소조건에서 상대적으로 감소하는 경향을 보였다. 또한, 주행 2시간 후에 급정거의 지시로부터 브레이크에 반응하는 시간은 저농도의 산소조건에 비하여 고농도의 산소조건에서 유의하게 감소하는 것으로 나타났다. 이상의 결과로부터 자동차 운전 중에 산소농도가 저하되면 현저하게 피로를 느끼게 되고, 고농도의 산소를 공급하는 경우는 상대적으로 피로감이 저하되며 반응시간이 단축되는 것으로 나타나, 산소공급에 의하여 운전자의 피로가 경감될 수 있다고 시사되었다.

• 한국치위생학회지
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• 제9권1호
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• pp.141-151
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• 2009

Cognitive degree of musculoskeletal symptoms and existence (or non-existence) of experience was conducted following dental hygienists' health habits, heath state and working environment targeting dental hygienists who were working for the dental clinics in Masan-si, Changwon-si and Jinhae-si in Gyeongsangnam-do for one year or more. The research findings were as follows. 1. Cognitive degree of musculoskeletal symptom following general characteristics was the highest among the subjects who were 40 years old or above. 2. As for the education level, cognitive degree of musculoskeletal symptoms was high while prevalence was low, which were statistically significant when the education level was higher. 3. Cognitive degree of musculoskeletal symptom was high when the subjects exercised, and cognitive degree of musculoskeletal symptom and prevalence were significantly high when they are engaged in leisure activities or hobbies. 4. Prevalence of musculoskeletal symptoms was statistically high if they are afflicted with disease, if they feel burdened by their job, if they suffer from considerable physical fatigue, if they feel chronic fatigue or if they feel that their health state is poor. 5. Cognitive degree of musculoskeletal symptom and prevalence were higher, which was statistically significant, when the number of years worked was higher. 6. Cognitive degree of musculoskeletal symptom was higher, but prevalence was lower when the time that they were seated was longer. This research demonstrated that the musculoskeletal disorders related to their job that afflicts the dental hygienists is not caused by one element, but it is possible to see that the musculoskeletal disorders results from the interaction of the diverse elements that are interrelated such as the subjects' characteristics and health habits and heath state, working environment and so forth including inappropriate work related movements. To this, dental hygienists need to improve their health habits so that they can form proper health habits that will ensure health in every day life on their own with the improvement of their every day life habit and positive self-evaluation to act on the health promotion behaviors, education and publicity, and measures to prevent and to manage musculoskeletal disorders in overall need to bepursued after in an active manner.

• 한국전문물리치료학회지
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• 제8권3호
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• pp.11-26
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• 2001

In rehabilitation programs involving muscle re-education and endurance exercise, it is necessary to confirm when fatigue occurs. It is also necessary to quantify fatigue, to confirm whether the muscle has been exercised sufficiently. In general, as fatigue occurs, the force-generating ability of the muscle is reduced. If the median frequency (MDF) obtained from electromyogram (EMG) power spectrum is correlated highly with work, then the timing and degree of fatigue may be confirmed. This study examined the relationship between work and MDF obtained from the EMG power spectrum during repetitive isokinetic exercise. Surface EMG signals were collected from biceps brachii and vastus lateralis of 52 normal subjects (26 males, 26 females) at $120^{\circ}/sec$ and $60^{\circ}/sec$ while performing an isokinetic exercise. The exercise was finished at 25% of peak work. MDF data was obtained using a moving fast Fourier transformation (FFT), and random noise was removed using the inverse FFT, then a new MDF data was obtained from the main signal. There was a high correlation between work and MDF during repetitiv isokinetic exercise in the biceps brachii and vastus lateralis of males and the biceps brachii of females (r=.50~.77). However, there was a low correlation between work and MDF in the vastus lateralis of females (r=.06~.19).

• 한국직업건강간호학회지
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• 제27권2호
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• pp.77-88
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• 2018

Purpose: This study aimed to investigate the degree of role conflict and its ambiguity, and fatigue in clinical nurses and to analyze the effect of these on their self-resilience in order to provide fundamental data for improving their working environment after the Middle East Respiratory Syndrome outbreak. Methods: After the collection of data from 258 clinical nurses in five general hospitals, t-test, ANOVA, Pearson's correlation coefficient, and multiple regression were performed using IBM SPSS Statistics 20.0. Results: A significant positive correlation was found between nurses' role conflict and ambiguity and fatigue; while a negative correlation was found between nurses' role conflict and ambiguity and self-resilience. A significant negative correlation was found between fatigue and self-resilience. According to the study results, the factor that affected clinical nurses' self-resilience the most was role conflict and its ambiguity, followed by marital status, fatigue, educational level, religion, and related tasks, which together accounted for 38% of self-resilience in clinical nurses. Conclusion: To improve weaknesses in nursing care after the Middle East Respiratory Syndrome outbreak, the scope of nursing care was changed upon the expansion of integrated nursing and care-giving services. Therefore, in the rapidly changing environment of nursing, policies to improve nursing performance, as well as successful reaction capability, are suggested.

• 대한기계학회논문집A
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• 제39권8호
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• pp.781-785
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• 2015

엔지니어링 플라스틱(Engineering Plastic ; EP)에 대한 내구성 평가를 위해 현재 새롭게 국내에서 개발한 초음파 피로시험법을 이용하여 EP 중에서도 결정화 속도가 빠르고 결정화도가 높은 범용 POM(Polyoxymethylene) 소재에 대한 초음파 가속피로시험 거동을 평가하고자 하였다. 이에 본 연구에서 사용된 POM 소재의 밀도는 $1.37g/cm^3$, 동탄성계수는 3.49 GPa 로 측정되었으며, 초음파피로시험 20kHz, 응력비 R= -1 의 판상시편 두께 (4t, 7t, 10t)에 따른 피로수명평가 결과 전체 응력진폭 5.0~6.0MPa 부위에서 피로한도를 확인하였다. 피로시험 후 파단 면을 관찰한 결과 7t, 10t 두께 시편의 크랙 시작위치에서 미소 공동들이 서로 연결된 형태의 잔금(crazing) 균열현상으로 파단된 dimple 구조형상을 전자현미경을 통해 확인할 수 있었다.

• 한국치위생학회지
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• 제17권6호
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• pp.1121-1134
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• 2017

Objectives: The purpose of this study is to analyze the factors affecting the self-perceived halitosis of adults and to utilize them as basic data for the development of prevention and management program to reduce of self-perceived halitosis. Methods: A questionnaire survey of 301 adults in their 20s and 50s living in Gwangju and Jeonnam selected by convenience sampling from July 1, 2017 to August 31, 2017 was conducted to investigate oral health status and behavior, fatigue and perceived stress. Statistical analysis was performed using frequency analysis, independent t-test, one way ANOVA, Pearson's correlation analysis, and multiple regression analysis. Results: The degree of self-perceived halitosis was higher in married (2.51) and unemployed (2.71), with tongue brushing (2.68), intention to participate in halitosis education (2.57), taking medication (2.73), coated tongue (2.82) and there was both otolaryngology and gastrointestinal disease (2.72) and periodontal disease (2.89) (p<0.05). Fatigue (${\beta}=0.237$), periodontal disease (${\beta}=0.196$), and coated tongue (${\beta}=0.237$) affect the self-perceived halitosis (p<0.001). Conclusions: The self-perceived halitosis in adults was correlated with fatigue and perceived stress. Also fatigue, periodontal disease, coated tongue factors were analyzed as factors influencing self-perceived halitosis. Additional studies such as prevention and management of periodontal disease and coated tongue, which is a factor of self-perceived halitosis in adults, and development of programs to reduce self-perceived halitosis for fatigue management, which is an external factor, are necessary.

• 한국해양공학회지
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• 제17권2호
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• pp.34-39
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• 2003

Recent deepwater offshore structures in the Gulf of Mexico utilize butt welded tubular joints. Application of a welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical, as the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimation of the fatigue behavior of these tubular members in the design stage is generally condrcted by using S-N curves, as specified in the codeds and standards. Applying the stress concentration factor of the welded structure to the S-N approach often results in a very conservative assessment, because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fatigue life analysis using fracture mechanics has been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. Still, there is inconsistency when designing tubular joints using a conventional S-N approach and when specifying weld flaw acceptance criteria using fracture mechanics approach. This study developed fatigue curves that are consistent with both the S-N approach and the fracture mechanics approach. Accounting for non-uniform stress distribution and threshold stress intensity factor were key parameters in relating both approaches. A series of S-N curves, generated from the fracture mechanics approach, were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02 ). The new curves for tubular joint agree very well with the experimental results. The comparison also indicated the degree of conservatism built into the API X design curve.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.69-74
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• 2003

Recent deepwater offshore structures in the Gulf of Mexico utilize butt welded tubular joints. Application of a welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical, as the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimation of the fatigue behavior of these tubular members in the design stage is generally conducted by using S-N curves, as specified in the codes and standards. Applying the stress concentration factor of the welded structure to the S-N approach often results in a very conservative assessment, because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fatigue life analysis using fracture mechanics has been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. Still, there is inconsistency when designing tubular joints using a conventional S-N approach and when specifying weld flaw acceptance criteria using fracture mechanics approach. This study developed fatigue curves that are consistent with both the S-N approach and the fracture mechanics approach. Accounting for non-uniform stress distribution and threshold stress intensity factor were key parameters in relating both approaches. A series of S-N curves, generated from the fracture mechanics approach, were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02). The new curves for tubular joint agree very well with the experimental results. The comparison also indicated the degree of conservatism built into the API X design curve.

• 근관절건강학회지
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• 제7권1호
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• pp.53-62
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• 2000

This study was designed to distinguish by the characteristic difference and the degree of symptoms such as fatigue, pain, coping to pain, and efficacy on pain, and to offer descriptive data for nursing intervention for improving coping ability to pain along each characteristics of disease in chronic arthritis and systemic lupus erythematosus. The subjects were 135 outpatients in the hospital for rheumatic disease in H-university, Seoul. The data were collected by structural questionnaire, from April 29 to June 29, 1999. The results were that the fatigue score was high in the OA patients while the RA patients and SLE patients experienced middle range of fatigue score, but which was not statistically different. Although the RA patients felt higher pain than other diseases, they have well coped with their pain than the others. In efficacy on pain the SLE patients had higher score than others but all of the disease showed lower score. No statistically significant difference among the three group was recorded in efficacy on pain. Therefore, pain management in the RA patients was primary nursing intervention because they felt severe pain and have well coped with pain while they had lower pain efficacy score than the others. It is also important that fatigue management and coping strategies on pain for the OA patients and SLE patients are specially supportive in the nursing intervention.

• Journal of Ginseng Research
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• 제35권3호
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• pp.331-338
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• 2011

Red ginseng (RG, the extract of Panax ginseng Meyer) has various biological and psychological activities and may also alleviate fatigue-related disorders. The present study was undertaken to evaluate what kind of fatigue red ginseng alleviate. Animals were orally administered with 50, 100, 200, 400 mg/kg of RG for 7 days. Before experiments were performed. Physiological stress (swimming, rotarod, and wire test) are behavioral parameters used to represent physical fatigue. Restraint stress and electric field test to a certain degree, induce psychological fatigue in animals. Plasma concentration of lactate and corticosterone (CORT) were also measured after these behavioral assays. RG supplementation (100 mg/kg) increased movement duration and rearing frequency of restrainted mice in comparison with control. 100 and 200 mg/kg of RG increased swimming time in cold water ($8{\pm}4^{\circ}C$) while at 100 mg/kg, RG increased electric field crossing over frequencies. 50, 100 and 200 mg/kg RG prolonged running time on the rotarod and at 100 mg/kg, it increased balancing time on the wire. RG at those doses also reduced falling frequencies. RG supplementation decreased plasma CORT levels, which was increased by stress. Lactate levels were not significantly altered. These results suggest that RG supplementation can alleviate more the damages induced by psychological than physical fatigue.