• Current Optics and Photonics
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• 제6권1호
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• pp.39-43
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• 2022

Underwater optical wireless communication (UOWC) is a good candidate for high-speed underwater wireless communication. In this work, we compare the performance of several modulation techniques for a UOWC system consisting of a light-emitting diode (LED) with an operating wavelength of 405 nm and a Si avalanche photodiode (APD). In this work, we consider six modulation schemes: 4-quadrature amplitude modulation (QAM), 8-QAM, quadrature phase shift keying (QPSK), binary phase shift keying (BPSK), on-off keying (OOK), and 4-pulse amplitude modulation (PAM). We also consider the cases of pure water and seawater for the working conditions. Our results show that 4-QAM and 8-QAM perform the best, in terms of communication distance and transmission power efficiency, for all water types considered.

• 한국산업보건학회지
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• 제17권3호
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• pp.254-260
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• 2007

Trichloroethylene(TCE) is widely used as a degreasing solvent in workplaces. TCE is primarily toxic to the nervous system, however, systemic disorder like Stevens-Johnson syndrome has been recently reported in small-scale factories, where the government has had limited information of chemical use. A survey was performed to investigate the actual condition of using TCE and to provide practical information to occupational health service agencies and professionals. This survey was carried out on 103 factories out of 430 factories which were conducted periodic work environment measurement for TCE. Degreasing was the most popular reason for using TCE in Korea, which reached to 94%. TCE was also used as a solvent for rubber in the coating or molding process, and adhesives in the bonding process. Metal fabrication was the most common as 23%, followed by assembling automobile parts (17%), and machinery (12%). Workers exposed to TCE during full-shift were 52% while 48% were exposed during short period of the shift or intermittently. Manual or semi-automatic work occupied 87% while automatic work was just 13%. Though automatic work by a closed system was generally lower exposed to TCE, compared to manual work, it can cause a high exposure when the maintenance system is improper. Semi-automatic work especially like open-top degreasing process can cause a high exposure when local exhaust system with condensing and refrigerating coils in the degreaser does not work well. In conclusion, the survey showed nationwide status of TCE exposure in various aspects. It can be used to monitor workplaces and workers exposed to TCE to prevent occupational diseases.

• 한국직업건강간호학회지
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• 제29권4호
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• pp.306-315
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• 2020

Purpose: This study was conducted to identify the effects of caffeine intake by shift workers on sleep, considering various variable related to the sleep health of shift workers. Methods: A descriptive survey study was conducted with 128 employees who worked shifts. Respondents were surveyed on their of caffeine intake behavior, schedule type, quality of sleep, health promotion behavior, and occupational stress. Differences in their quality of sleep were assessed using the t-test and analysis of variance, while factors influencing the effect of caffeine intake on the quality of sleep were analyzed using hierarchical logistic regression. Results: The average Pittsburgh Sleep Index, Korean Version score of those surveyed was 7.3±3.25, indicating that their quality of sleep was low. On the other hand, their aveage daily intake of caffeine was 1.6±0.99 cups (1 cup =150 mL) and 116.4±77.58 mg/dL of caffeine. When the various variables that could have affected the quality of sleep were corrected, an increase in the amount of caffeine consumed was found to lead to a decrease in the quality of sleep (p=.015). Conclusion: Caffeine intake by shift workers has a significant bearing on their quality of sleep; therefore, such intake should be adjusted to improve their sleep health.

• Advances in aircraft and spacecraft science
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• 제7권1호
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• pp.79-90
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• 2020

The dynamic coupling between shaker and test-article has been investigated by recent research through the so called Virtual Shaker Testing (VST) approach. Basically a VST model includes the mathematical models of the test-item, of the shaker body, of the seismic mass and the facility vibration control algorithm. The subsequent coupled dynamic simulation even if more complex than the classical hard-mounted sine test-prediction, is a closer representation of the reality and is expected to be more accurate. One of the most remarkable benefits of VST is the accurate quantification of the frequency down-shift (with respect to the hard-mounted value), typically affecting the first lateral resonance of heavy test-items, like medium or large size Spacecraft (S/Cs), once mounted on the shaker. In this work, starting from previous successful VST experiences, the parameters having impact on the frequency shift are identified and discussed one by one. A simplified analytical system is thus defined to propose an efficient and effective way of calculating the lower bound frequency shift through a simple equation. Such equation can be useful to correct the S/C lateral natural frequency measured during the test, in order to remove the contribution attributable to the shaker in use. The so-corrected frequency value becomes relevant when verifying the compliance of the S/C w.r.t. the frequency requirement from the Launcher Authority. Moreover, it allows to perform a consistent post-test correlation of the first lateral natural frequency of S/C FE model.

• 수면정신생리
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• 제9권1호
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• pp.41-47
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• 2002

목 적 : 여러 모의 연구(simulated study)에서 순환제 교대근무자의 야간 근무에 따른 수면장애와 작업수행의 어려움에 대해 광치료가 치료적 도구로 제안되고 있어 실제 순환제 교대 근무 환경에서의 야간 근무 동안 광치료의 효과를 평가하고자 하였다. 방 법 : 연구대상인 5명의 병동 근무 간호사들은 기초평가단계 동안 연속적인 3일간의 낮 근무 후 650 lux의 실내 조명 하에서 연속적인 3일간의 야간근무를 하도록 계획되었으며, 2주 후의 광치료시행단계에서는 동일한 순환주기로 근무하는 동안 자정부터 오전 4시까지 2500 lux의 광박스를 이용한 광치료를 시행하였다. 야간근무 후의 낮수면은 actiwatch를 이용하여 평가되었으며 야간 근무 동안은 스탠포드 졸리움 척도를 이용한 각성상태, 고막체온, STIM을 이용한 수행능력 및 visual analogue를 이용한 우울감, 불안감, 신체적 불편감, 피로감을 기초평가단계와 광치료시행단계 각각에서 야간근무 첫째날과 셋째날을 비교평가하였다. 결 과 : 야간근무 후의 낮 수면은 기초평가단계와 광치료 시행단계 모두 야간 근무 1일째와 3일째에 유의한 차이를 보이지 않았다. 일주기리듬의 위상 변화를 알아보기 위해 측정된 고막 온도는 야간근무 3일째에 기초평가단계에서는 위상전진을 나타낸 반면 광치료시행단계에서는 위상변화가 없었다. 또한, 각성상태, 우울감, 불안감, 피로감, 신체적 불편감, 졸리움 등의 변화도 기초평가단계에서 야간근무 3일째에 유의하게 악화된 반면 광치료시행단계에서는 변화가 없었다. 주의력에서는 광치료시행단계에서만 야간근무 3일째가 1일째에 비해 유의하게 호전되는 양상을 나타내었다. 결 론 : 본 연구는 위약효과를 배제할 수는 없지만, 실제근무 환경에서 단기간의 광치료가 순환제 교대근무자들의 주간 수면의 질을 뚜렷하게 변화시키진 않았으나, 야간 근무동안 졸리움 감소와 주의력 향상을 통한 야간 업무 수행능력의 호전 가능성을 제시해 주고 있다.

• 수면정신생리
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• 제7권2호
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• pp.96-101
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• 2000

목 적 : 본 연구는, 교대근무자에 있어 세 교대근무간의 수면양상과 자율신경계활동성을 비교함으로써, 근무자들은 어떤 근무시에 가장 적합하다고 느끼는지 그리고 교대근무자의 심리적, 신체적 문제점의 특성은 무엇인지를 알아보고자 하였다. 또한 본 연구는 근무자들이 교대근무에 좀 더 효과적으로 적응하는데 도움을 주고자 기획되었다. 방 법 : 3일 정도 연속적으로 한 교대근무를 한 후 1일 휴무, 그 다음에 다른 교대로 넘어가는 빠른 순환주기의 교대근무자 51명이 연구에 참여하였다. 각 대상은 수면일기를 작성하였으며 수면잠복기, 수면기간시간, 수면 중 깨어난 횟수를 세 교대근무간에 비교하였다. Epworth 졸음척도와 시각아날로그척도를 사용하여 졸음을 평가하였으며 기분상태는 기분상태척도로 평가하였다. 심박수변동성과, 스트레스 호르몬(아드레날린, 노르아드레날린) 및 그 대사산물을 측정하여 자율신경계 활동성을 살펴보았다. 심박수변동성에는 저주파영역의 스펙트럼 파워, 고주파영역의 스펙트럼 파워, 저주파영역의 파워와 고주파영역의 파워간의 비가 포함되었다. 결 과 : 수면기간시간은 오후근무시 가장 길었고 수면잠복기는 밤근무시 가장 짧았다. 깨어났을 때의 각성도는 오전근무시 가장 저하되었고 작업 중의 각성도는 밤근무 중 가장 떨어지는 것으로 나타났다. 밤근무시 근무자들은 신체적인 피곤감과 인지기능의 저하를 호소하였다. 심박수변동성의 비교를 통해 오후근무시 부교감신경계가 가장 활성화된다는 것을 알 수 있었으며 아드레날린 및 노르아드레날린 분비도 통계적인 의미는 없었지만 오후근무시 가장 감소하였다. 결 론 : 본 연구결과 오후근무가 교대근무자에게 가장 적합한 것으로 나타났다. 오전근무시에는 빛을 아침에 투여하고 밤근무시에는 근무 중에 빛을 투여하면 교대근무에의 적응이 촉진될 것으로 생각된다.

• 대한간호학회지
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• 제50권5호
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• pp.646-657
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• 2020

Purpose: The purpose of this study was to identify the quality of sleep in novice and experienced shift work nurses and compare the factors associated with their quality of sleep. Methods: We analyzed the data of 192 and 256 novice and experienced nurses, respectively. The quality of sleep, sleep hygiene, job stress, and fatigue were measured using Insomnia Severity Index, Sleep Hygiene Practice Scale, the Korean Occupational Stress Scale, and Fatigue Severity Scale. Data were analyzed using SPSS 25.0 to calculate descriptive statistics and logistic regression. Results: Sleep quality was lower in experienced nurses (12.55 ± 5.71) than in novice nurses (11.18 ± 5.78). Fatigue was more severe in experienced nurses (4.47 ± 1.13) than in novice nurses (4.23 ± 1.12). In the logistic regression, factors related to sleep quality in novice nurses were sleep hygiene (odds ratio; OR = 1.06, p < .001) and fatigue (OR = 2.49, p < .001). Factors related to sleep quality in the experienced nurses were also sleep hygiene (OR = 1.04, p = .001) and fatigue (OR = 1.53, p = .012). Conclusion: Sleep quality of experienced nurses is lower than those of novice nurses. Factors associated with sleep quality in novice and experienced nurses are equally identified as sleep hygiene and fatigue. Therefore, personal efforts to improve sleep hygiene, such as providing comfortable sleep environment, are needed. Furthermore, organized efforts to decrease fatigue, such as constructing a working environment with a bright light at night and providing a fatigue-decreasing program that includes meditation, are required.

• 보건의료산업학회지
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• 제6권2호
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• pp.211-217
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• 2012

To identify health behavior of Peptic ulcer patients among all employees in Korea and examine relevant factors to present basic data for improving Korean adult employees' health conditions and quality of living, 3,515 employees aged 20 to 69 were sampled from the group that responded to the question concerning the presence of Peptic ulcer in the fourth Korea National Health and Nutrition Examination Survey for the third year (2009). After logistic regression analysis was carried out to see the effects of working conditions, harmful factors, shift work, stress perception, and experience of depression on the presence of Peptic ulcer, it was found that unsafe or unpleasant working conditions led to higher risk of getting Peptic ulcer, that flexible workers were more likely to get Peptic ulcer, and that depression or stress perception exerted almost no effect on Peptic ulcer. With the increase in the number of flexible workers, increasingly more interest is taken in the effects of shift work on health; occupational Peptic ulcer tends to become chronic as compared with the condition in the general population and reappear even after recovery in many cases; therefore, it is necessary to take special management measures by estimating the number of those at a risk of getting Peptic ulcer and by finding out its risk factors.

• Safety and Health at Work
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• 제8권1호
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• pp.29-35
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• 2017

Background: Despite our knowledge of the causes of cancer, millions of workers are involuntarily exposed to a wide range of known and suspected carcinogens in the workplace. To address this issue from a policy perspective, we developed a policy framework based on a prospective health policy analysis. Use of the framework was demonstrated for developing policies to prevent cancers associated with diesel engine exhaust (DEE), asbestos, and shift work, three occupational carcinogens with global reach and large cancer impact. Methods: An environmental scan of existing prospective health policy analyses was conducted to select and describe our framework parameters. These parameters were augmented by considerations unique to occupational cancer. Policy-related resources, predominantly from Canada, were used to demonstrate how the framework can be applied to cancers associated with DEE, asbestos, and shift work. Results: The parameters of the framework were: problem statement, context, jurisdictional evidence, primary prevention policy options, and key policy players and their attributes. Applying the framework to the three selected carcinogens illustrated multiple avenues for primary prevention, including establishing an occupational exposure limit for DEE, banning asbestos, and improving shift schedules. The framework emphasized the need for leadership by employers and government. Conclusion: To our knowledge, this is the first proposal for a comprehensive policy framework dedicated to the primary prevention of occupational cancer. The framework can be adapted and applied by key policy players in Canada and other countries as a guide of what parameters to consider when developing policies to protect workers' health.

• 한국콘텐츠학회논문지
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• 제22권4호
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• pp.689-699
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• 2022

본 연구는 귀지압이 교대근무를 수행하는 간호사의 변비와 우울에 미치는 영향을 알아보기 위해 시행되었다. 자료수집기간은 2021년 5월부터 6월까지이며, I지역의 A대학병원에서 교대근무를 하는 간호사 40명을 연구대상으로 하였다. 이 연구는 무작위배정, 공개시험, 대조군 비교설계를 이용한 실험연구이다. 40명의 변비를 가진 간호사가 실험군(n=20) 혹은 대조군(n=20)으로 무작위 배정되었다. 실험군에게 변비와 우울의 귀지압 상응점에 귀지압 스티커를 붙이고 2주간 유지한 결과 실험군은 대조군에 비해 변비점수가 통계적으로 유의하게 감소하였다(F=7.74, p<.001). 실험군에서 지압 전·후 우울점수의 차이(2.90±2.86)가 대조군에서의 차이(1.35±3.12)보다 컸으나 통계적으로 유의하지는 않았다(t=-1.64, p=.055). 본 연구 결과 귀지압이 교대근무 중인 간호사의 변비 완화에 효과가 있음을 확인하였다. 귀지압은 변비가 있는 대상자에게 사용할 수 있는 치료 방법의 하나로 고려될 수 있다.