• 대한인간공학회지
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• 제32권6호
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• pp.549-555
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• 2013

Objective: The purpose of this study was to compare the performance of drilling on the ceiling in three different postures (standing, standing on the ladder and supine on the height adjusted board) and the subjective responses of perceived discomfort after the drilling. Background: Overhead work has been identified as a major occupational risk factor and has been a main research subject. Method: Ten young participants drilled 20 holes at the pre-marked places on the ceiling in three different postures. The drilling duration, resting and drilling heart rate were measured. The levels of perceived discomfort at neck, shoulder, elbow, hand and overall body were asked at the end of each task. Results: The working posture affected the heart rate after the drilling. Perceived discomfort in the neck decreased significantly in supine compared to drilling on the ladder. Conclusion: The results of this study suggest that drilling in supine can be an alternative way to reduce the drilling heart rate and the level of perceived discomfort in the neck without sacrificing the productivity. Application: The results of this study would be considered when drilling on the ceiling is required in construction workers.

• 대한인간공학회지
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• 제28권1호
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• pp.9-19
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• 2009

Repetitive movement, inadequate working posture, overuse of force, physical contact with sharp edge, vibration and temperature were well known risk factors of WMSDs (Work-related Musculoskeletal Disorders). Many researchers have investigated the relationship between inadequate working postures and incidences of WMSDs of the upper extremities, whereas relatively few researchers have tried to evaluate workload associated with the lower-body postures. The effects of lower-limb postures including various knee flexion angles on the subjective discomfort, heart rate and EMG of lower-limb muscles were investigated in this study. Thirty graduate students were asked to maintain thirteen different body postures, and heart rate and EMG data of five muscle groups (electro spine, biceps femoris, vastus medialis, gastrocnemius and tibialis anterior) from each posture were collected during fifteen minutes sustaining tasks. All participants were also asked to report their discomfort ratings of body parts. Results showed that high subjective discomfort ratings and heart rates were reported at the postures of knee angles of $60^{\circ}$ and $90^{\circ}$, whereas low discomfort ratings were founded at the postures of chair heights with 20cm, 40cm, and sitting with crossed legged. The change of median frequency for each muscle group during fifteen minutes tasks was investigated for each body posture to evaluate the relationship between muscle fatigue and body posture. It was found that the trends of changes of median frequency were different based on muscle group as well as lower-limb body posture from this study.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.593-601
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• 2020

This study was conducted to analyze the physical strain with heart rate monitor in timber harvesting operations in order to reduce occupational accidents. The timber harvesting activities are manual cutting(felling, limbing and bucking) with a chainsaw and extraction by cable yarder. The study took place on Japanese larch stand. The average height was 26m and average diameter at breast height(DBH) was 3 7cm. The havest unit was gentle slope to steep slope. Results showed that the heart rate increases for chocking, felling, limbing and bucking were 94.0%, 87.9%, 84.8% and 56.4% respectively. The rate of Work Load Index was higher in the limbing(61.4%) activity than other activities chocking(55.2%), felling(54.1%) and bucking(32.1%). During 50% working heart rate test it was found that limbing(1.09), chocking(1.05) and felling(1.04) was exposed to high work intensity compared to bucking(0.83). The results showed that maximum acceptable work times(felling, chocking and limbing) were 2.30 hour, 1.85 hour and 1.60 hour respectively. To avoid occupational accidents, timber harvest workers may use a suitable working hour schedule to felling, chocking, limbing.

• 한국의류학회지
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• 제24권8호
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• pp.1266-1275
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• 2000

This study was to research the actual condition of a dropworts working environment and to develope the clothing to reduce the work road. The actual conditions of working environment, working position and clothing were surveyed. Experiments were performed in the chamber and in the field. In the chamber, rectal temperature, 11 points skin temperatures(forehead, chest, abdomen, upperarm, forearm, dorsum manus, palm, thigh, calf, dorsum pedis and pelma), heart rates, microclimates inside clothing on the chest and subjective sensations were measured for comparing between 2 different types o garments. In the field, rectal temperature, abodomen skin temperature, 3 points microclimates inside clothing(chest, back and thigh), heart rates, the volume of EMG and subjective sensations were measured. The results were as follows; 1. There were no significant differences in rectal temperature between a old type protective clothing and a new type both in the chamber and the field. 2. Subjects wearing a old type clothing responded \"a little cold\", \"a little uncomfortable\" and subjects wearing a new type protective clothing responded \"normal\", \"comfortable\" both in the chamber and the field. 3. In the field test results, abodemen skin temperature in a old type clothing was higher and microtemperatures inside clothing of chest, back and thigh in a new type protective clothing were higher. 4. The volume of EMG was lower in the new type protective clothing than in the old one.protective clothing than in the old one.

• Journal of Chest Surgery
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• 제25권11호
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• pp.1203-1208
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• 1992

Current methods of myocardial protection has been improved with cardioplegia and hypothermia. We compared St. Thomas hospital cardiopleic solution without oxygenation[Group I], with oxygenation[Group II] and with oxygenation with filter[Group III] under isolated working heart model. Heart rate recovery was more significantly improved in Group II than Group I after 15 minutes of recovery time [p<0.05]. Maximal systolic pressure shows no difference as it increases with time. Cardiac ouputs were not diffrent between groups. Recovery time was shorter significantly in group II and group III than group I [p<0.05] Use of filter showed no difference. As a conclusion, oxygenated cardioplegic solutions improves ability to protect the heart against ischemia and it is manifested by improved recovery time and heart rate.

• 대한가정학회지
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• 제41권7호
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• pp.107-120
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• 2003

This study was purposed to explore children's development in the theory of mind. Children of age 7, 9 and 11 explained others' good and bad behaviors, and answered to questions about ‘mind’ and ‘heart’ Children's behavior explanations with internal factors, including traits and mental states, were scored and analyzed. The responses of mind-related knowledges were categorized and compared by age. Results showed that children's internal explanations were not different with age, and most of the children explained internally for others' bad behaviors more than for good ones. Secondly, children conceptualized cold-minded ‘mind’ and hot-minded ‘heart’ differentially, but showed developmental differences in mind-related knowledges. It was hard for the younger children to explain ‘mind’ and ‘heart’ Children came to construct their knowledge with age; ‘mind’ including cognitive monitoring, and ‘heart’ working outside the personal emotions.

• 한국산림과학회지
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• 제87권2호
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• pp.121-130
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• 1998

별도작업에서 작업원의 작업강도를 파악하기 위하여, 체인톱을 이용한 낙엽송 간벌작업에서 작업시간과 작업량을 조사하였으며, 작업시 심박수의 변화를 조사하였다. 또한, 작업원의 최대 작업수행 능력을 평가하기 위하여 최대산소섭취량을 조사하였다. 1일 실작업시간은 6시간 6분으로 오전작업시간이 약 3시간 12분, 오후가 2시간 54분으로 나타났고, 전체작업시간 중 실작업시간의 약 90% 정도를 차지하는 것으로 나타났으며, 실작업시간 중 요소작업 의 시간비율은 이동(Movement)의 비율이 평균 26.3%로 가장 큰 값을 보였다. 작업원의 작업량을 분석하기 위하며 시간당 벌목재적을 조사한 결과 평균 $2.62m^3/hr$로 나타났다. 작업원의 작업능력을 평가하기 위하여 최대산소섭취량을 분석한 결과, 평균 $2.42{\ell}/min$($46.5m{\ell}/kg/min$)으로 나타났으며, 작업시 심박수를 바탕으로 체인톱을 이용한 낙엽송 간벌작업 중 실동시간의 작업강도를 분석한 결과, 실동시간의 심박수 증가율은 평균 93.2%로 나타났고, 작업강도지수는 평균41.9%로 나타났다.

• Annals of Occupational and Environmental Medicine
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• 제35권
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• pp.24.1-24.15
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• 2023

Background: The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance. Methods: We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state. Results: Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point. Conclusion: The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

• Journal of Chest Surgery
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• 제23권4호
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• pp.646-653
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• 1990

Currently numerous methods are in use for myocardial protection from the ravages of ischemia and hypoxia. This study was designed to compare with FDP-GIK[Group II, n=8] and GIK cardioplegic solution[Group I, n=8] in ability of myocardial protection and was examined in the isolated working rat heart subjected to long period[120 min] of hypothermic[10 - 15K] ischemic arrest with multidose[every 30 min] cardioplegic infusion. During postischemic reperfusion period 20 min, hemodynamic functions[aortic flow, coronary flow, peak aortic pressure, cardiac output, heart rate], biochemical enzymatic & electrical activities were evaluated. The time from onset of reperfusion to the return of regular sinus rhythm was significantly reduced from 87$\pm$3 sec to 17$\pm$2 sec[P<0.05]. The postischemic recovery of aortic flow was better in the group II [95.1$\pm$3.3% of its preischemic control level] than in the Group I [75.4$\pm$6.8%] [P<0.05]. Cardiac output and stroke volume was also better in the group[91.3$\pm$1.6%, 89.4$\pm$2.6%, respectively] than in the Group I [79.1$\pm$3.7%, 77.0$\pm$4.8%, respectively] [P<0. 05]. Creatine kinase leakage was also significantly reduced from 33.8$\pm$4.9 IU /10 min / gm * dry weight to 15.4$\pm$3.6 IU /10 min /gm * dry weight[P<0.05]. It is suggested that adding FDP to GIK cardioplegic solution improves its ability to protect the heart against long period of hypoxic ischemia.

• 한국보건간호학회지
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• 제4권2호
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• pp.59-77
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• 1990

The purpose of this study was to provide the basic data for the effective health management of the industrial workers, by classifying factors influencing their perceived symptoms to examine their health status and identifying the inter' relationship of their perceived symptom with their working department. the environment of working area and their general characteristics. The study was undertaken from October 1 to November 30. 1989. The subjects were 999 workers who had worked in Industrial Corps located in Chungbuk Province. The results of this study were as follows: I . Worker's perceived symptoms were classified according to the following eight factors; 1) musculo - skeletal symptoms of shoulder, neck, back and arm 2) optical symptoms 3) symptoms in head(such as headache and dull) 4) musculo - skeletal symptoms of leg and lower back 5) gastro - intestinal symptoms 6) mental symptoms. 7) neural symptoms 8) lung and heart symptoms II . The degrees of workers' perception of perceived symptoms; Mean score of perceived symptoms:7.0 The rank of degrees of perceived symptoms: The highest:musculo - skeletal symptoms of shoulder, neck, back, and arm The second:optical symptoms The third:musculo - skeletal symptoms of leg and lower back The fourth:mental symptoms the fifth:gastro-intestinal symptoms m . Analysis of the inter-relationship of perceived symptoms with working department, environment of working area and general characteristics; 1) sexuality The difference of degrees of perceived symptoms was significant;femanle was higher than male(P<0.000). 2) level of education The difference of degrees of perceived symptoms according to the level of education was significant; The higher the level of education, the higher the degree. 3) working department The working department played a significant part in the degrees of perceived symptoms of workers; Workers of assembling department:musculo-skeletal symptoms both of shoulder. neck, back and arm and of leg and lower back(P<0.000). Workers of inspection department:optical symptoms(P<0.05). Office workers:mental symptoms(P<0.05). 4) kinds of job The difference of the degrees of perceived symptoms according to kinds of job was significant; Workers dealing with chemical materials and workers dealing with job with high tension:gastro-intestinal symptoms and symptoms in head. Workers dealing with weighty things or working a long time with the same posture:musculo-skeletal symptoms both of shoulder, neck, back and arm and of lower back(P<0.000). 5) working posture The difference of the degrees of perceived symptoms related with working posture was significant; Sitting:optical symptoms(P<0.0000) and symptoms in head(P<0.005) Standing:musculo-skeletal symptoms of leg and lower back(P<0.0000). 6) satisfaction with their own duty The more dissatisfien they were. the higher became the degrees of their perceived symptoms(P<0.0001). 7) satisfaction with their working condition The more dissatisfied with their working condition they were, the higher became the degrees of their perceived symptoms(P<0.001). 8) environment of working area The environment of working area played a significant part in the degrees of perceived symptoms of workers; Workers exposed to most of the factors of the environment of working area were higher than those not exposed in the degrees of musculoskeletal symptoms. Workers in the noisy environment:optican symptoms(P<0.000), symptoms in head(P<0.005). Workers in the damp environment:optical symptoms(P<0.005) and lung and heart symptoms(P <0.01). Workers with illumination problem:optical symptoms(P<0.000), mental symptoms(P<0.005) and neural symptoms(P<0.01). Workers with ventilation problem:optical symptoms and lung and heart symptoms(P<0.001)