• 환경위생공학
• /
• 제21권2호
• /
• pp.57-68
• /
• 2006

This study was designed to provide basic data on preventive plans by affecting factors that have analysed on musculoskeletal diseases. The survey were conducted from July 1 to 30, 2004 among 600 hair dressers working in Seoul and Gwangju using self-administration questionnaire. The results of this study are summarized as follows: The pain experience rate of musculoskeletal diseases. in the last one yea was 55.2%. 35.7% of respondents answered they had pain on shoulders, 30.6% had pain on legs and feet, 28.9% had pain on waist, 26.8% had hands, fingers and wrist, 22.3% had pain on necks and 17.6% had pain arms and elbows more than disease on necks, shoulders, arms and elbows, hands, fingers and wrists, waist, shoulders legs and feet. The prevalence rate of the last week was 40.3%. The prevalence rate in each body parts of the last week was 23.3% on legs and feet, 21.2% on shoulders, 20.8% on waist, 14.9% on hands, fingers and wrists, 14.4% on necks, 9.3% on arms. The affecting factors on musculoskeletal disease index were analysed by multiple linear regression analysis. there are working posture$(\beta=0.27)$; authority of task$(\beta=0.18)$, self-conscious stress $(\beta=0.16)$, age$(\beta=0.14)$, physical burden from work$(\beta=0.13)$, and task required$(\beta=0.10)$. Determinant coefficients was 22.7%. Based on the results above, working posture, job stress and physical burden from task are highly related with pain. In order to prevent musculoskeletal disease of hairdressers, working posture shall be improved and leisure opportunities to relieve stress, and health management education shall be provided.

• 대한인간공학회지
• /
• 제26권2호
• /
• pp.45-59
• /
• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• 대한인간공학회지
• /
• 제21권2호
• /
• pp.59-70
• /
• 2002

This paper is about the evaluation of stress response and recovery using biosignals and fuzzy theory. We caused mental stress by means of a coin-stacking task. During the experiment, 4 kinds of biosignals, including frontalis EMG, ECG, peripheral skin temperature and skin conductance level, were acquired. Then, the degree of stress was assessed by synthetically those signals using fuzzy inference. From the fuzzy inference result, the parameters (amount of physiological change / amount of imposed stress) and (time to 25% recovery), which represent response and recovery respectively, were derived. We made a two-dimensional point graph using the response parameter as an abscissa and the recovery parameter as an ordinate for each subject.

• 말소리와 음성과학
• /
• 제14권4호
• /
• pp.19-24
• /
• 2022

This study examined which acoustic cue(s) that Korean learners of English give weight to in perceiving English lexical stress. We manipulated segmental and suprasegmental cues in 5 steps in the first and second syllables of an English stress minimal pair "object". A total of 27 subjects (14 native speakers of English and 13 Korean L2 learners) participated in the English stress judgment task. The results revealed that native Korean listeners used the F0 and intensity cues in identifying English stress and weighted vowel quality most strongly, as native English listeners did. These results indicate that Korean learners' experience with these cues in L1 prosody can help them attend to these cues in their L2 perception. However, L2 learners' perceptual attention is not entirely predicted by their linguistic experience with specific acoustic cues in their native language.

• The Korean Journal of Physiology and Pharmacology
• /
• 제9권1호
• /
• pp.63-68
• /
• 2005

Hydrogen peroxide ($H_2O_2$) causes oxidative stress and is considered as an inducer of cell death in various tissues. Two-pore domain $K^+$ ($K_{2p}$) channels may mediate $K^+$ efflux during apoptotic volume decreases (AVD) in zygotes and in mouse embryos. In the present study, we sought to elucidate linkage between $K_{2p}$ channels and cell death by $H_2O_2$. Thus $K_{2p}$ channels (TASK-1, TASK-3, TREK-1, TREK-2) were stably transfected in HEK-293 cells, and cytotoxicity assay was preformed using cell counting kit-8 (CCK-8). Cell survival rates were calculated using the cytotoxicity assay data and dose-response curve was fitted to the $H_2O_2$ concentration. Ionic currents were recorded in cell-attached mode. The bath solution was the normal Ringer solution and the pipette solution was high $K^+$ solution. In HEK-293 cells expressing TREK-1, TREK-2, TASK-3, $H_2O_2$ induced cell death did not change in comparison to non-transfected HEK-293. In HEK-293 cells expressing TASK-1, however, dose-response curve was significantly shifted to the left. It means that $H_2O_2$ induced cell death was increased. In cell attached-mode recording, application of $H_2O_2$ (300μM) increased activity of all $K_{2p}$ channels. However, a low concentration of $H_2O_2$ ($50{\mu}M$) increased only TASK-1 channel activity. These results indicate that TASK-1 might participate in $K^+$ efflux by $H_2O_2$ at low concentration, thereby inducing AVD.

• 터널과지하공간
• /
• 제32권6호
• /
• pp.568-585
• /
• 2022

본 연구에서는 3차원 입자기반 개별요소모델(grain-based distinct element model, GBDEM)을 이용하여 암석 균열의 열에 의한 미끄러짐 거동을 해석하였다. 이는 DECOVALEX-2023 프로젝트 Task G에 참여하여 수행한 연구로, 해석대상은 한국건설기술연구원에서 수행된 saw-cut 균열 시료에 대한 열-역학적 하중 재하 실험 결과이다. 여기에서는 암석 시험편을 Voronoi 다면체의 집합체로 모델링하고, 개별요소법 코드인 3DEC을 통해 입자와 입자 간 경계면, 내부에 포함된 균열에서의 열-역학적 연계거동을 해석하였다. 주요 해석내용은 가열로 인한 암석 표면의 온도 분포, 열응력의 증가에 따른 주응력 변화, 균열의 전단변위와 수직변위이다. 해석 결과, 상기 수치모델은 실내실험에서 관찰된 열전달과 열손실 특성, 열에 의한 균열의 점진적 전단파괴 프로세스, 변위의 제한으로 인한 열응력의 증가 등을 합리적 수준에서 재현하고 있는 것으로 나타났다. 그러나 가열에 의한 전단파괴 시점, 열응력 증분과 변위 크기 등에서는 다소 차이를 보였다. 본 연구의 해석모델은 Task G에 참여하는 국외 연구팀들과의 의견 교류 및 협력을 통해 지속적으로 개선, 검증할 예정이다.

• 시큐리티연구
• /
• 제18호
• /
• pp.21-37
• /
• 2009

본 연구에 목적은 경호원의 직무유형과 스트레스 수준이 8-OHdG, 면역 글로브린, T-cell, NK-cell과 항산화 효소 등에 미치는 영향을 알아보는 있었다. 연구 대상은 경호원 경력이 2년 이상으로 경호업무를 수행하는 경호원 60명으로 하였다. 집단 구분 및 집단별 인원 분포는 경호직무에 따른 집단은 국가요인경호집단(N=23명), 사설개인경호집단(N=23명), 기타 경호집단(N=14명) 등으로 구분하였다. 집단 스트레스 수준에 따른 집단은 스트레스 수준을 측정하여 스트레스 측정 점수에 따라 집단을 낮은 하(下)스트레스 집단(N=14명), 중(中)스트레스 집단(N=26명), 고(高)스트레스 집단(N=20명) 등 세 집단으로 구분하였다. 실험은 직무 유형에 따라 대상별로 스트레스를 측정한 후 혈액을 채혈하여 직무유형과 스트레스에 따른 생화적 변인의 결과치를 변량분석하여 검증한 결과 다음과 같은 결론을 얻었다. 첫째, 경호원의 직무유형에 따라 스트레스 수준은 국가요인 경호집단의 스트레스 수준이 가장 높게 나타났다(p<.05). 둘째, 경호원의 직무유형과 스트레스 수준에 따른 8-OHdG는 직무유형에 따라서는 차이가 없었으며(p>.05), 스트레스 수준에 따라서는 유의한 차이가 있었다(p<.05).

• 산업융합연구
• /
• 제18권4호
• /
• pp.9-14
• /
• 2020

이 연구는 고등학교 교사들의 그릿과 스트레스 대응행동 간의 관계를 분석하고, 그릿의 군집유형별 직무 스트레스 대응행동의 차이를 알아보기 위해 실시되었다. 교육부 중앙교육연수원에서 실시하는 연수에 참여한 고등학교 교사 226명을 대상으로 설문조사를 실시하였다. 연구 결과는 다음과 같다. 첫째, 그릿의 노력 지속성은 도전적 및 정서완화 대응행동에 정적 예측변인이었고, 흥미일관성은 회피적 대응행동에 부적 예측변인이었다. 그리고 높은 그릿과 높은 노력 군집 유형이 낮은 그릿 군집 유형보다 도전적 대응과 정서완화 대응행동의 평균이 높았다. 연구 결과를 토대로 고등학교 교사들이 직무 스트레스에 효과적으로 대응하도록 지원하기 위해서 교사의 그릿을 강화할 필요성을 시사점으로 제시하였다.

• 구강회복응용과학지
• /
• 제17권2호
• /
• pp.75-84
• /
• 2001

The purpose of this study is to to analyze the mechanical stress on articular disk of the dentated skull with the condition of unilateral posterior molar missing. For this study, the three dimensional finite element model of human skull scanned by means of computed tomography. (G.E. 8800 Quick, USA) was constructed. The finite element model of jaws is composed of 98,394 elements and 38,321 nodes, and it consists of articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. Boundary condition included rigid restraints at the first molar and endosteal cortical surfaces of the insertion points of temporal bone. The data derived from Nelson's study were used for the loading conditions of mandible during clenchings and for maxilla, new loading and constraint conditions were applied. A clenching task during intercuspal position was modeled to the three dimensional finite element model. The stress level and displacement of articualr disc on the model with unilateral posterior molar missing under bilateral clenching task can be analyzed. During bilateral clenchings, the compressive stress level and diplacement of the articular disk on the side of unilateral posterior molar missing is greater than that on the case with full dentition, whereas a higher stress was found on the disk on the balancing side of the full dentition. Although this kind of study is not enough to explain the role of occlusion as an etiologic factor of TMD, there may be a possibiliy that the condition of posterior molar missings may contribute in part to the TMJ biomechanics.

• Journal of Acupuncture Research
• /
• 제29권3호
• /
• pp.89-99
• /
• 2012

Objectives : This study was performed to investigate the effect of simple acupuncture and electroacupuncture at Bai Hui($GV_{20}$) on heart rate variability in healthy adults with stress task. Methods : 40 healthy volunteers participated in this study. HRV was recorded before and after stress. And then simple acupuncture(SA group) was applied at $GV_{20}$ or electroacupuncture(EA group) was applied at the same spot in each treatment group for 20 minutes. No treatment was performed in control group for 20 minutes. Then HRV was recorded. Results : 1. In all groups, LF norm, LF/HF, HF norm showed significant changes after mental stress. 2. Control group showed no significant change. In SA group, HF norm LF, LF norm and LF/HF showed a significant change after treatment. In EA group, Mean HR, HF, LF norm, HF norm and LF/HF showed a significant change after treatment. In both treatment groups, there were significant differences after treatment compared to control group. 3. In EA group, HF and HF norm decreased significantly after treatment compared to SA group. Conclusions : These results suggest that simple acupuncture and electroacupuncture at $GV_{20}$ affect the balance of the autonomic nervous system and that electroacupuncture at $GV_{20}$ enhances parasympathetic activation more than simple acupuncture.