• Structural Engineering and Mechanics
• /
• 제71권5호
• /
• pp.553-562
• /
• 2019

This paper presents the results of a study into the dynamic behaviour of a support structure of a mobile elevating work platform. The vibrations of the mechanical system of the observed structure are examined analytically, numerically, and experimentally. Within the analytical examination, a simple mathematical model is developed to describe free and forced vibrations. The dynamic analysis of the mechanical system is conducted using a discrete dynamic model with a reduced number of vibrational degrees of freedom. On the basis of the expression for the system energy, and by applying Lagrange's equations of the second kind, differential equations are derived for system vibrations, frequencies are determined, and the laws of forced platform vibration are established. At the same time, a nonlinear FEM model is developed and the laws of free and forced vibration are determined. The experimental and numerical part of the study deal with the examination of the real structure in extreme conditions, taking into account: the lowest eigenfrequency, forced actions that could endanger the general stability, the maximal amplitudes, and the acceleration of the work platform. The obtained analytical and numerical results are compared with the experiments. The experimental verification points to the adverse behaviour of the platform in excitation cases - swaying. In such a situation, even a relatively small physical force can lead to unacceptably high amplitudes of displacement and acceleration - exceeding the usual work values.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.205-209
• /
• 2015

A significant amount of data including ongoing construction activities, work quantities, resources utilized by contractors, and site conditions is collected in highway construction sites on a daily basis by resident engineers. This data is commonly known as daily work reports (DWRs) in the U.S. Although a lot of time and effort is invested in collecting the DWR data, its utilization has been very limited. This paper discusses current practices of collecting and utilizing DWR data among various Departments of Transportation in the U.S., and discusses the challenges and opportunities for better collection and utilization of the data. An extensive literature review and two nationwide surveys in the U.S. were conducted as a part of this study. Finally, it provides a set of recommendations to effectively address the challenges identified and maximize the benefits of utilizing DWR data such as supporting various decisions for highway project development process. The findings of this study are implementable ideas that can aid DOTs in making data-driven decisions throughout the project development processes in the future.

• 한국직업건강간호학회지
• /
• 제32권4호
• /
• pp.152-163
• /
• 2023

Purpose: This study aimed to identify the effects of musculoskeletal symptoms and burden on presenteeism among nurses in a gastrointestinal endoscopy unit. Methods: This was an observational cross-sectional study. Data were collected through self-reported questionnaires administered to 140 nurses working in the gastrointestinal endoscopy unit of a hospital located in Busan metropolitan city. Results: The body part with the most musculoskeletal symptoms was the back (73.2%), and the most common musculoskeletal burden work was "when you have to stand or maintain the same posture for a long time in a lead apron protection clothes." The factors most related to work impairment were working hours, musculoskeletal symptoms, and musculoskeletal burden, with an explanatory power of 63.3%. Factors affecting perceived productivity were working hours and musculoskeletal symptoms, with an explanatory power of 29.2 %. Conclusion: To reduce work impairment and increase the perceived productivity of nurses in gastrointestinal endoscopy units, various programs and improved working environments are needed that can improve musculoskeletal symptoms and reduce musculoskeletal burden.

• 경영정보학연구
• /
• 제10권3호
• /
• pp.133-153
• /
• 2008

정보화 사업에 대한 투자성과가 언제부터 어떻게 나타날 것인가의 시차 연구는 정책개발 및 정보시스템 도입 시 의사결정에 중요한 연구이다. 그러나 대부분의 정보화 성과평가 방법론들은 평가시점에 따라 사전/과정/사후평가의 한 시점에서 평가할 뿐 시간 경과에 따른 정보를 제공하는데는 한계가 있다. 이에 본 연구에서는 정보화 효과 분석 및 시차와 관련한 선행연구들을 살펴보고 전자정부 사업의 일환으로 추진된 산업인력정보화 사업의 워크넷 시스템에 대한 시차효과를 파악하는 방법론을 제시하고, 이를 실증 분석하였다. 본 연구에서는 DB 데이터를 이용한 시차분석, 이용자들의 업무프로세스 분석을 통한 시차분석, IT투자 대비 효과를 이용한 시차분석 등 다양한 관점에서 시차효과 분석방법을 제시하였다. 또한 다양한 시차효과 분석방법을 국가인적자원개발 및 노동시장활성화를 지원하는 워크넷에 적용하여 검증을 시도하였다. 본 연구를 통해 시차분석을 위한 몇 가지 방법론을 제시하였으며, 산업인력 정보화사업의 성과가 시차를 두고 향상되었다는 것을 발견하였으며, 정보화와 성과 간에 발생하는 시차현상의 존재 가능성에 대한 시사점을 제시하였다.

• 가족자원경영과 정책
• /
• 제20권2호
• /
• pp.43-56
• /
• 2016

Time poverty is a kind of objective and subjective state which a person does not have a enough time to do his/her work or is in the mood to do something in a hurry. The major of family resources management has studied time as a resource to manage for long years. How to manage time has been a major part in education of family resources management. The education itself in nature has focused to inform knowledge and the disciplines of time management, to the students, on the other way, has a rare interest with a each student how to apply them or whether do in practical. Coaching is characterized as a practical learning and mutual communication skills with open questions, which help for a individual student to find his/her own goal related with time poverty or furthermore, whatever he/she wants to achieve in life. If the benefits of the education of family resources management as well as the benefits of practical learning of coaching could be merged in education on time management, the effectiveness of education to resolve time poverty is able to be increased. For the purpose, this study suggests a coaching approach in education of family resources management to resolve time poverty, by some comparisons of family resources management and coaching about time and time management.

• Journal of the Korean Statistical Society
• /
• 제29권1호
• /
• pp.45-62
• /
• 2000

Rotation design is a sampling technique to reduce response burden and to estimate the population characteristics varying in time. Park and Kim(1999) discussed a generation of one-level rotation design which is called as {{{{r_1^m ~-r_2^m-1}}}} design has more applicable form than existing before. In the structure of {{{{r_1^m ~-r_2^m-1}}}} design, we derive the exact variances of generalized composite estimators for level, change and aggregate level characteristics of interest, and optimal coefficients minimizing their variances. Finally numerical examples are shown by the efficiency of alternative designs relative to widely used 4-8-4 rotation design. This is continuous work of Part Ⅰ studied by Park and Kim(1999).

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.716-719
• /
• 1995

Although design process is a creative work, it includes a lot of iterations. Statistics show that about 15 to 40 percent of the total design activity is spent on time-consuming retrieval of technical informations such as standard part, handbook, engineering equation,previous design and so on. On the other hand, product structure and parts specifications change with the design process, which also need to be traced accordingly. The BOM, design history, and all the relecant technical informations can be managed can be efficiently within a unified framework called configuration. This paper presents a prototype of a configuration manager which is a part of the engineering data management system for machine tools.

• Toxicological Research
• /
• 제17권
• /
• pp.37-39
• /
• 2001

As the preliminary data collection for further chemical risk assessment. toxicants rating works is now rather extensively implemented in China. It consists of two parts, ie., rating of the hazard level of the exposed toxicant and that of the toxicant's profession. In the first part, the rating are based on six criteria, ie., acute toxicity, incidence of acute poisoning, prevalence of chronic poisoning, consequence of chronic poisoning, carcinogenecity and MAC level. Four hazardous levels are to be classified as extreme, high, medium, mild. In the second part. three determinants as weighted coefficients are taken into account, ie., toxicant's hazard level. exposure time and folds of MAC surpassing. Eventually, the index of classification C by which the work with toxic hazard can be classified is able to be calculated and assessed. Several comments were discussed and new recommendations were demonstrated.

• Journal of Welding and Joining
• /
• 제15권2호
• /
• pp.43-53
• /
• 1997

The complete joining method for dissimilar press punch materials and its real-time evaluation method is not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. This work was carried out to determine the proper friction welding conditions and to analyze mechanical properties of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch) using aluminum (A6061 for the interlayer material) as an insert material between the sintered carbide tool materials and the alloy steel. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.838-841
• /
• 2000

To improve the accuracy of products and improve the product quality, we need to enhance the machining accuracy of the machine tools. To this point of view, measurement and inspection of finished part as well as error analysis of machine tools has been studied for last several decades. OMM(On the Machine Measurement) has been issued to alternate with CMM, pointing out disadvantages of high expenses and lots of setting time in CMM. In this paper, we study 1) the spherical surface manufacturing by volumetric error compensation of machine tool, 2) the system development of OMM without detaching work piece from a bed of machine tool after working. 3) the generation of the finished part profile by On the machine measurement. Furthermore, the output of OMM is compared with that of CMM, and verified the feasibility of the measurement system.