• 한국지능시스템학회논문지
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• 제16권6호
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• pp.683-690
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• 2006

무선 센서 네트워크에서 에너지 소비의 효율성은 전체 네트워크 수명 시간을 결정하기 때문에 에너지 소비를 최소화하기 위한 연구가 활발히 진행되고 있다. 무선 센서 네트워크에서 에너지 보전을 위해서는 운영에 필요한 최소한 센서 노드만을 활성화된 상태로 유지하고 나머지 노드들은 휴면 상태로 유지하여 불필요한 에너지 소비가 일어나지 않도록 하여야 한다. 그러나 얼마만큼의 센서 노드들을 최적의 운영 노드 집합에 포함시킬 것인지를 계산하는 것은 NP-hard 문제로 알려져 있다. 본 논문에서는 최적에 근접한 커버 집합(cover set)을 생성하기 위하여 CVT 기반의 근사화 알고리즘을 제안하였다. 제안된 알고리즘에서는 센서의 통신 범위가 센싱 범위의 두 배 이상이면 커버 집합에 속한 센서 노드 간의 연결이 즉시 이루어지도록 하고 반면에 통신 범위가 센싱 범위의 두 배 이하이면 커버 집합의 접속성 보장을 위하여 보조 노드를 결정하는 연결 기법을 제시하였다. 마지막으로 제안된 알고리즘의 성능 평가를 위하여 이론적 분석과 실험을 수행하였으며, 실험결과를 통해 제안된 알고리즘이 Greedy 알고리즘보다 CCS(Connected Cover Set)의 크기와 실행 시간 측면에서 우수함을 보였다.

• 한국농공학회지
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• 제30권2호
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• 대한간호학회지
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• 제14권1호
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• pp.21-33
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• 1984

The purpose of this study was to define the relationship between the leadership style of head nurses and the burnout level of nurses by taking into consideration the factors which influence the level of burnout and which show how burnout varies according to the leadership style of lead nurses. The subjects of the survey were 355 ward nurses and their 48 head nurses working in five university hospitals in Seoul. The nurses were surveyed by means of a questionnaire from Sept. 22 though Sept. 29, 1983. The Leadership Scale devised by Fleishman, and modified by Lee, and the Burnout Scale developed by Pines et al, and adapted to the Korean situation by Peek, were used as a basis of ;his survey This researcher subjected the questionnaire to a pre-test and to an internal reliability consistency test through item analysis. For the purpose of analysis of the data, the general characteristics were set at Mean and the general characteristics of head nurses in relation to the level of burnout of nurses was analysed by the Pearson Correlation Coefficient. The relation between head nurses' general characteristics 3nd leadership style, the relation between nurses' general characteristics and level of burnout and the level of burnout of nurses according to the different style of leadership of head nurses were analysed by ANOVA. A summary of the results of the study is as follows. 1. Hypothesis:“That the burnout level of the nurse will be different according to the leadership style of the head nurse”was supported. 2. Analysis of the relationship between the head nurse's general characteristics and the leadership style of the head nurse showed that the leadership style of the head nurse was not related to age and experience as head nurse. 3. Analysis of the relationship of nurses' burnout levels to general characteristics of nurses showed statistically significant differences in burnout levels according to working departments, expected working period and reasons for selecting nursing as a profession. Also, the burnout level of nurses was negatively related to the head nurse's age and experience as a head nurse.

• 한국치위생학회지
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• 제13권6호
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• pp.917-923
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• 2013

Objectives : The purpose of this study was to investigate the level of expertise and awareness of information on toothpaste in dental hygienists and to give patients information on toothpaste. Methods : The subjects was 205 dental hygienists working at dental clinic, dental hospital or college dental hospital in Seoul and Gyeonggi-do. They filled out the questionaire from 13th to 27th April, 2013. Collected data were analyzed by SPSS 21.0 program and significant level was set at p=0.05. Results : The awareness of information on toothpaste was the highest in dental hygienists having under 3 years career and working at dental clinics(p<0.001). The level of expertise on toothpaste was the highest in those having over 5 years career and working at general hospital or college dental hospital(p<0.001). In association with the effect of toothpaste(p<0.05), experienced dental hygienists had a higher knowledge(1.68 point) that those who had no experience(2.27 point). Instruction of the oral care devices included 27.5% of dental floss, 27.1% of toothbrush and 25.4% of proxabrush, and 4.9% of toothpaste. Conclusions : The results revealed that the right choice of the toothpaste would be the best prevention of dental caries and it is necessary to educate the dental hygienists for the toothpaste information.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.75-80
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• 2006

국제노동기구(ILO)는 해상근로자의 근로조건 향상과 양호한 근로환경의 보장 및 근로인격의 향상을 위하여 꾸준한 노력을 기울려 왔으며 1996년까지 채택된 39개의 해사협약과 29개의 권고 채택하였다. 기존 해사협약은 새로운 해상 근로 환경의 변화에 따른 요구를 충족하지 못하며, 중복되는 것이 많고, 복잡한 개정구조로 인한 최신화의 어려움 등, 여러 문제점이 있다는 것이 제기 되어 왔다. 이에 ILO는 2001년부터 해사 노동기준의 기존내용을 최신화하고, 통합하는 작업을 시작하여 2006년 2월 23일 2006년 해사노동협약(Maritime Labour Convention2006)을 채택하였다. 따라서 여기에서는 기존 해사협약에서는 볼 수 없었던 새로운 사항에 관한 특징을 중심으로 그 의의에 관하여 살펴보고, 향후 해운산업에서의 해사노동 문제에 미치는 영향에 관하여 논하고자 한다.

• 한국항해항만학회지
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• 제31권1호
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• pp.115-119
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• 2007

국제노동기구(ILO)는 해상근로자의 근로조건 향상과 양호한 근로환경의 보장 및 근로인격의 향상을 위하여 꾸준한 노력을 기울려 왔으며 1996년까지 채택된 39개의 해사협약과 29개의 권고를 채택하였다. 기존 해사협약은 새로운 해상 근로 환경의 변화에 따른 요구를 충족하지 못하며, 중복되는 것이 많고, 복잡한 개정구조로 인한 최신화의 어려움 등, 여러 문제점이 있다는 것이 제기되어 왔다. 이에 ILO는 2001년부터 해사 노동기준의 기존 내용을 최신화하고, 통합하는 작업을 시작하여 2006년 2월 23일 2006년 해사노동협약(Maritime Labour Convention 2006)을 채택하였다1). 따라서 여기에서는 기존 해사협약에서는 볼 수 없었던 새로운 사항에 관한 특징을 중심으로 그 의의에 관하여 살펴보고, 향후 해운산업에서의 해사노동 문제에 미치는 영향에 관하여 고찰하였다.

• 한국재료학회지
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• 제15권11호
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• pp.705-710
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• 2005

NIL (nanoimprint lithography) technique has demonstrated a high potential for wafer size definition of nanometer as well as micrometer size patterns. During the replication process by NIL, the stiction between the stamp and the polymer is one of major problems. This stiction problem is moi·e important in small sized patterns. An antistiction layer prevents this stiction ana insures a clean demolding process. In this paper, we were using a TCP (transfer coupled plasma) equipment and $C_4F_8$ as a precursor to make a Teflon-like antistiction layer. This antistiction layer was deposited on a 6 inch silicon wafer to have nanometer scale thicknesses. The thickness of deposited antistiction layer was measured by ellipsometry. To optimize the process factor such as table height (TH), substrate temperature (ST), working pressure (WP) and plasma power (PP), we were using a design of experimental (DOE) method. The table of full factorial arrays was set by the 4 factors and 2 levels. Using this table, experiments were organized to achieve 2 responses such as deposition rate and non-uniformity. It was investigated that the main effects and interaction effects between parameters. Deposition rate was in proportion to table height, working pressure and plasma power. Non-uniformity was in proportion to substrate temperature and working pressure. Using a response optimization, we were able to get the optimized deposition condition at desired deposition rate and an experimental deposition rate showed similar results.

• 한국직업건강간호학회지
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• 제27권4호
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• pp.224-234
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• 2018

Purpose: In this study, we attempted to analyze the occupational accident experience rate by working life cycle of Korean workers considering entrance and turnover in their jobs. The specific goal of this study was to calculate the accident experience rate according to workers' turnover history and previous accident experience. Methods: We constructed a cumulative data set of 90,338 cases of workers' accident experiences in their jobs from the Fourth Korean Working Conditions Survey. The accident experience rates according to workers' turnover and previous accident experiences were analyzed using descriptive statistics and analysis of variance. Results: In this study, the cumulative accident experience rate of Korean workers was found to be 5.2%. It was confirmed that the accident experience rate of workers increased as the turnover frequencies increased. In addition, we analyzed only the data of the workers who had experienced turnover and found that the accident experience rate after turnover increased about 7.5 times when workers had experienced accidents in the past. Conclusion: To prevent occupational accidents in workers, safety strategies should consider a worker's previous job history and injury experiences. It will also be necessary to focus preventive efforts on new and young workers through ongoing monitoring and on-the-job training.

• 한국안전학회지
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• 제37권6호
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• pp.102-107
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• 2022

South Korea will soon be a super-aged society, as more than 20.6% of its population will be 65 years and older by 2025. As of 2022, 17.5% of the total population in South Korea is 65 years and older, which exceeds the set threshold for an aged society, where more than 14% of the population is 65 years and older. The proportion of older subway construction workers has increased. Aging workers and their work stress negatively impact their workability. A previous study demonstrated that the stress index measured using the uBioMacpa measurement device (Macpa stress index) had a significant correlation with work stress in South Korea. The device tests vascular health and measures stress levels via Macpa signal analysis. In this study, the pulse waves of subway construction workers were measured using uBioMacpa to identify their stress levels. The stress levels were analyzed by age, years of service, job position, employment type, and work type. Herein, these statistics could not be easily represented by a normal distribution; therefore, the Kruskal-Wallis test, a nonparametric statistical method, was used for the analysis of data. The results showed that age, job position, employment type, and working type affected the Macpa stress index and the stress levels of workers increased with age. In terms of job position, technical engineers were more stressed than other workers because of their poor working environment. In terms of employment type, daily-wage workers were more stressed than other workers. In terms of working type, tunneling, waterproofing, and construction scored the highest Macpa stress indexes without any significant difference, whereas earthworks scored the lowest. Based on the analysis of Macpa stress index, safety and health management plans were proposed to reduce the stress levels of workers. Moreover, a manual for efficient stress management must be developed for subway construction workers.

• 한국산업보건학회지
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• 제33권3호
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• pp.291-297
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• 2023

Objectives: An epidemiological investigation was requested for a worker who developed COPD and IPF after long-term molding and firing at a domestic tile manufacturing site. We would like to share the results of the exposure assessment and the estimation of past work. Methods: The content of crystalline silica in four raw materials was analyzed, and the respirable fraction of crystalline silica and dust generated in the air from molding and firing workers and other processes were measured. The measurement and analysis method referred to the NIOSH method. Results: The crystalline silica content of the raw material was 24~47%. The concentration of crystalline silica in the molding and firing process workers and the surrounding area was at the level of the exposure standards set by the Ministry of Employment and Labor and ACGIH, and the respirable and total dust exposure levels were generally low. The crystalline silica concentration of the area samples measured to estimate past work was about twice as high as the exposure standard of the Ministry of Employment and Labor (0.05 mg/m3), and the exposure levels of respirable dust were also quite high at 0.903 and 1.332 mg/m3. Conclusions: It was confirmed that tile molding and firing workers are currently exposed to a fairly high level of crystalline silica, and a high level is also confirmed in area samples to estimate past work. In the past, it is judged that the level of exposure would have been much higher due to differences in production volume, working method, presence/absence of local ventilation facilities, and process layout. When working in such a working environment for a long time, respiratory diseases such as lung cancer, COPD, and IPF can occur.