• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.27-39
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• 1996

배관을 구속시키기 위한 원통형 배관 지지대 (Trunnion Pipe Support)가 부착된 배관의 응력해석 을 위하여 유한요소해석을 사용하였다. 해석결과로 부터 얻어진 응력은 두께에 대한 평균 및 선 형 응력으로 분류 되었으며, 분류된 응력값은 압력에 의한 일차응력계수(B$_1$)와 이차응력계수(C$_1$), 모멘트에 의한 일차응력계수(B$_2$)와 이차응력계수(C$_2$)를 추정하기 위하여 ASME Code에 정의된 것과 일치하게 해석되었다. 무차원의 함수로써 응력계수에 대한 경험식을 개발하기 위하여 여러 모델의 해석을 수행하였다.

• Safety and Health at Work
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• 제9권2호
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• pp.232-235
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• 2018

Background: This study was conducted to investigate the heat stress and semen quality among male workers in a steel industry in Iran and investigate the relationship between heat stress indices and semen parameters. Methods: The study was conducted on workers exposed (n = 30) and unexposed (n = 14) to heat in a steel industry. After obtaining a brief biography of the selected employees, scrotal temperature, oral temperature, and environmental parameters were measured, and their semen samples were analyzed according to the procedure recommended by the World Health Organization. The heat stress indices, including wet-bulb globe temperature (WBGT) and predicted heat strain (PHS), in their workplace were calculated according to environmental parameters (ISO 7243:1989 and 7933:2004, respectively). Results: Time-weighted averages of WBGT and PHS ($35.76^{\circ}C$ and 491.56 $w/m^2{\frac{w}{m^2}}$, respectively) for the exposed group were higher than threshold limit values. The mean difference of environmental, physiological, and semen parameters (exception: pH of semen), and also WBGT and PHS indices were statistically significant (p < 0.05) between the two groups. Mean semen parameters were in the normozoospermic range. WBGT and PHS indices showed significantly "negative" correlation with physiological parameters (scrotal and oral temperature) and most semen parameters (semen volume, sperm morphology, sperm motility, sperm count; p < 0.05); moreover, the correlation of WBGT with these parameters was stronger than PHS. Conclusion: Semen parameters of the studied workers exposed to heat were in the borderline level of normozoospermic range, and their semen parameters were significantly lower than controls. For better assessment of occupational environment concerning physiological and semen parameters in steel industries, WBGT can be a more useful index.

• Journal of Animal Science and Technology
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• 제64권5호
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• pp.970-984
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• 2022

Thermal stress is a tremendous health predicament encountered by poultry farmers with adverse effects on the performance, product stature, health condition, survival, and overall welfare of poultry birds, and so requires urgent dietary user-friendly strategy to curb. This study was conducted with 200-day old broilers for the purpose of investigating the potential of phytogenics in refining the negative effects of heat stress on broiler chicken. Moringa, Phyllanthus and mistletoe leaves were processed as phytogenic supplements and incorporated into standard ration for broilers as treatments B1 (control), B2, B3 and B4 diet during the peak of thermal discomfort in humid tropics. Growth and carcass indices were monitored in a 49-day trial and blood samples were harvested at the end of the ordeal period to assess haematology, serum biochemical and oxidative stress markers with the use of standard procedures. The results obtained showed that the prevailing environmental condition in the study site indicated that the birds were exposed to heat stress. Birds fed on moringa and mistletoe supplements had higher performance index than birds without supplementation during heat stress condition, while birds fed on mistletoe supplement had the highest survival rate across the treatments. The liveweight, slaughter weight, dressed weight and eviscerated weight of heat stressed birds fed on moringa, phyllanthus and mistletoe supplements were significantly higher than birds on control treatment. Heterophyl/lymphocyte ratio of heat stressed birds without supplement were higher than birds on phytogenic supplements, with least values recorded in phyllanthus and mistletoe fed birds. Birds on phytogenic supplement tend to have lower cholesterol profile, lipid peroxidation and better antioxidant profile than birds on control treatment during heat stress conditions. Mistletoe supplementation in broiler ration enhances the survival rate, as well as promotes growth indices better among the phytogenic supplements. However, phytogenic supplements did ameliorate the negative effects of thermal discomfort on performance, physiological and oxidative stress in heat-stressed broiler chicken.

• 감성과학
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• 제21권1호
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• pp.71-82
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• 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.

• Computers and Concrete
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• 제22권2호
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• pp.133-142
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• 2018

The deterioration of existing bridges has become a major problem around the world. In the paper, a new model and an associated stress checking method are proposed for concrete box girders strengthened by external prestressing. The new model called the spatial grid model can analyze all the spatial behaviors clearly by transforming the box girder into discrete orthogonal grids which are equivalent to plate elements. Then the three-layer stresses are employed as the stress checking indices to evaluate the stress state of the plate elements. The initial stress check before strengthening reveals the cracked and potential cracking areas for existing bridges, making the strengthening design more targeted and scientific; the subsequent stress check after strengthening evaluates the strengthening effect and ensures safety. A deficient bridge is selected as the practical example, verifying the accuracy and applicability of the proposed model and stress checking method. The results show that principal stresses in the middle layer of plate elements reflect the main effects of external prestressing and thus are the key stress checking indices for strengthening. Moreover, principal stresses check should be conducted in all parts of the strengthened structure not only in the webs. As for the local effects of external prestressing especially in the areas near anchorage and deviator, normal stresses check in the outer and inner layers dominates and local strengthening measures should be taken if necessary.

• Safety and Health at Work
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• 제9권1호
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• pp.10-16
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• 2018

Background: A detailed evaluation of the underground mine climate requires extensive measurements to be performed coupled to climatic modeling work. This can be labor-intensive and time-consuming, and consequently impractical for daily work comfort assessments. Therefore, a simple indicator like a heat stress index is needed to enable a quick, valid, and acceptable evaluation of underground climatic conditions on a regular basis. This can be explained by the unending quest to develop a "universal index," which has led to the proliferation of many proposed heat stress indices. Methods: The aim of this research study is to discuss the challenges in identifying and selecting an appropriate heat stress index for thermal planning and management purposes in underground mines. A method is proposed coupled to a defined strategy for selecting and recommending heat stress indices to be used in underground metal mines in the United States and worldwide based on a thermal comfort model. Results: The performance of current heat stress indices used in underground mines varies based on the climatic conditions and the level of activities. Therefore, carefully selecting or establishing an appropriate heat stress index is of paramount importance to ensure the safety, health, and increasing productivity of the underground workers. Conclusion: This method presents an important tool to assess and select the most appropriate index for certain climatic conditions to protect the underground workers from heat-related illnesses. Although complex, the method presents results that are easy to interpret and understand than any of the currently available evaluation methods.

• 한국산업보건학회지
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• 제33권4호
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• pp.464-470
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• 2023

Objectives: This study evaluated occupational exposures to noise and heat stress during routine non-outage works in three coal-fired power plants in the Republic of Korea. Methods: The data were collected during the summer of 2020. Full shift noise exposure of 52 workers were measured using noise dosimeters. Heat stress of 16 worksites were measured for 70 minutes using wet-bulb globe temperature monitors. Results: The noise dosimetry results revealed time-weighted averages that ranged from 47.5 to 88.9 dBA. 2 out of 52 noise measurements exceeded 85 dBA. Based on the arithmetic mean, the coal service group showed the highest level at 80.2 dBA by job tasks. Noise exposures exceeding 85 dBA were measured in the coal service and plant operator group. Heat stress index measurements ranged from 20.3℃ to 37.2℃. 1 out of 9 indices measured in coal facilities and 4 out of 7 indices measured in boiler house exceeded 1 hour TWA during moderate work. Heat stress indices measured from boiler houses were significantly higher than those measured from coal equipment. Conclusions: The results show that overexposure to noise and heat stress may be encountered during routine non-outage work activities in coal-fired power plants. Appropriate actions should be taken to reduce future health outcome from occupational exposure to noise and heat stress in the industry.

• 한국학교보건학회지
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• 제27권3호
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• pp.159-168
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• 2014

Purpose: The purpose of this study is to provide implications for National Curriculum design for elementary and secondary school, by analyzing social indices of students' real life based on Oliva's three types of demand for education. Three types of demand are physical, social-psychological and educational demand. Methods: This study mainly analyzed recent research data and existing studies relevant to social indices to show students' real life. Results: Three types of social indices about educational demand showed that students have many difficulties in much learning time, lacking in sleeping time and physical activities, much stress and suicide attempt. It is supposed that learning and academic achievement is the main factor to make such kind of stress. Conclusion: Health & safety education, self-esteem inspiring education, reduction of learning burden, physical activities etc are needed to be more reflected in National Curriculum design in the future.

• 대한인간공학회지
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• 제26권1호
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• pp.11-18
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• 2007

The physiological and biochemical responses of healthy men and women to life stress were measured in order to temperature, blood pressure (BP), heart rate (HR) and galvanic skin response (GSR) were selected as physiological stress indices and salivary cortisol level was used as a biochemical stres biomarker. Twenty six (male 14 and female 13) colege students were participated in the experiment. Female showed the significant higher value of salivary cortisol level (p<0.01), diastolic BP (p<0.01), and HR (p<0.01) than male. The difference of skin temperature between forehead and fingertip correlated significantly with salivary cortisol level (p<0.01). The LF(low frequency)/HF(high frequency) ratio of HRV also correlated significantly with salivary cortisol level (p<0.01). However, BP, HR and GSR corelated insignificantly with salivary cortisol level. We suggest that LF/HF ratio of HRV and skin temperature may be good indices for the assessment of life stress, and may apply to measure the stress level of individual in real time.

• 대한원격탐사학회지
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• 제37권6_1호
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• pp.1559-1572
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• 2021

다중분광카메라의 기술 개발로 인해 구조적 특성뿐만 아니라 생화학적, 생리적 특성을 가지는 식생지수를 다양한 공간 규모에서 활용할 수 있게 되었다. 이에 본 연구는 스트레스를 받은 노지작물을 대상으로 지상 초분광계 및 무인기 영상 기반 구조적, 생화학적, 생리적 계열의 식생지수 반응을 평가하였다. 마늘을 대상으로 서로 다른 생육시기에 고농도의 제초제를 살포하여 약해 처리하였으며, 정상 생육에 비해 지상부 건물중이 46.9~84.5% 감소하는 등 큰 피해가 나타났다. 제초제를 살포한 처리구에서 근적외선 분광반사도 값은 꾸준하게 감소하였으며, 구조적 식생지수에서 작물의 약해 피해가 명확하게 표현되었다. 생화학적 식생지수의 경우 일부 지수를 제외하고는 작물의 피해 상태를 표현하였으나 생리적 식생지수는 잎이 고사하고 드러나는 멀칭비닐의 영향으로 약해 피해를 해석하기에 어려움이 있었다. 제초제 살포 후 서로 다른 공간 규모에서 관측된 식생지수의 감소율 차이는 구조적 식생지수의 경우 평균적으로 2.3%로 나타났으며, 정규화 식생지수의 경우 1.3~4.1%의 분포를 보였다. 비록 생리적 식생지수가 작물 스트레스에 민감하다고 알려졌지만, 노지작물의 경우 작물 스트레스 종류와 재배 환경에 따라 적합한 식생지수를 활용하여야 한다는 것, 공간 규모에 따른 오차를 최소화하기 위해서는 정규화 식생지수를 활용해야 한다는 것을 확인하였다.