• 해양환경안전학회지
• /
• 제25권3호
• /
• pp.306-312
• /
• 2019

This paper investigates to design a controller for maritime autonomous surface ship (MASS) by means of adaptive super-twisting algorithm (ASTA). A input-out feedback linearization method is considered for multi-input multi-output (MIMO) system. Sliding Mode Controller (SMC) is suitable for MASS subject to ocean environments due to its robustness against parameter uncertainties and disturbances. However, conventional SMC has inherent disadvantages so-called, chattering phenomenon, which resulted from the high frequency of switching terms. Chattering may cause harmful failure of actuators such as propeller and rudder of ships. The main contribution of this work is to address an appropriate controller for MASS, simultaneously controls surge and yaw motion in severe step inputs. Proposed control mechanism well provides convergence bewildered by external disturbances in the middle of steady-state responses as well as chattering attenuation. Also, the adaptive algorithm is contributed to reducing non-overestimated value of control gains. Control inputs of surge and yaw motion are displayed by smoother curves without excessive control activities of actuators. Finally, no overshoot can be seen in transient responses.

• 한국전자통신학회논문지
• /
• 제19권1호
• /
• pp.127-136
• /
• 2024

뿌리산업의 유해한 작업 환경과 높은 작업 강도는 작업자의 건강에 영향을 미칠 수 있기 때문에 기존에는 유해한 물질로부터 현장 작업자를 보호하기 위해 반년 단위로 작성한 환경을 측정하여 규제하고 있다. 그러나 작업환경 외에 작업자 건강 상태 등에 대해서는 정량화된 관련 기준이 부재하여 상시로 피해를 주는 임계치 이하 유해 물질의 지속적인 노출에 따른 직업병을 예방하는데 어려움이 상존하고 있다. 따라서 본 논문에서는 기계학습을 이용한 뿌리산업 작업 환경의 위험도 피크레벨 결정방법을 제안하고 이를 토대로 작업장의 실시간 안전 평가를 가능하게 하였다.

• 한국문화재보존과학회:학술대회논문집
• /
• 한국문화재보존과학회 2005년도 제22회 학술대회 발표 논문집
• /
• pp.100-103
• /
• 2005

Lichens play an important role in breaking down rocks physically and chemically. Physical weathering occurs mechanically through hyphae and rhizines growing into the rocks. Lichen substances such as oxalic acid, acidic polysaccharides and depsides may assist altering rocks chemically. These actions partly contribute to soil formation but prove harmful for the substratum. Some people do not like to keep lichens on stained glassof churches or on gravestones mainly because of its unglamorous appearance. A biocide, 'Koretrel', is very effective in removing lichens and blue-green algae from the surface of concrete. After spraying 'Koretrel' in the open air, lichens (Caloplaca sp., Endocarpon petrolepideum, Physciella melanchra, Phaeophyscia hispidula, etc.) growing on buildings died within three months and peeled off fromthe substratum. One year after treatment, concrete surfaces were almost lichen free for three or four years. The biocide makesuse of a kind of lichen substance and harmless both for substances and environment. Our recent experiments show that it is also useful for water grasses growing on the surface of an aqueduct of a hydroelectric power station.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2003년도 추계학술대회 논문집
• /
• pp.266-271
• /
• 2003

Many port states such as New Zealand. the USA. Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organism and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason. they perceived that the ballast exchange in deep sea is the most effective method. together with submitting the ballast management plan which contains the effective exchange method. ballast system and safety consideration. In this study, we make an effort to develop optimum ballast water exchange management and in result of that. it provide more convenient and stable process to prepare ballast water management plan for Bulk Carrier.

• 동력기계공학회지
• /
• 제7권1호
• /
• pp.14-19
• /
• 2003

A diesel engine has been widely used for ship and industry power because it has many merits of high thermal efficiency, reliability and durability. However its exhaust gas is harmful to human and air environment. Reducing the hurtful exhaust gas emissions, the study of the gas flow in the inlet and exhaust manifold is in progress in the world. In this paper we modeled the gas flow as one dimensional isentropic flow to predict the gas flow in the exhaust manifold. The method of characteristics was used for the model calculation, and the calculated results were compared with the experimental ones.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.477-480
• /
• 2005

In this paper, the concept of sustainability was applied to mechanical design and manufacturing of mobile-phone case. A new evaluation method to find products' good and weak point for sustainability was developed. Two mobile phones were evaluated using the evaluation tool. As a result, electro-magnetic (EM) wave was considered as a harmful factor of the products, and improved front panel was made using nano particles that absorb EM waves. The EM shielding tests revealed that silver nano powders absorbed EM while MWCNT had no effect.

• 농촌의학ㆍ지역보건
• /
• 제35권1호
• /
• pp.21-35
• /
• 2010

There are many work-related injuries and diseases of fisheries in Korea. Fishermen have exposed to harmful environment, such as natural disasters, ultraviolet, noise, vibration, organic solvents, ergonomic risk factors, loss of fresh water and food, and psychologic stress. They have suffered from numerous work-related health problems, including musculoskeletal disorders, cardiovascular diseases, infectious diseases, pyschological diseases, decompression sickness, and so on. Sea accidents can cause deaths of fishermen and if sea pollution is occurred, fishermen have a great economic damage. However, the concern of these injuries and diseases has been little because they are small in number and have decreased. Fisheries are important core industries, so the problems of fisheries have to be solved by a government. But work-related injuries and diseases are not investigated properly and accurate diagnoses are not made due to loss of concern. We hope that this article will be a cornerstone to solving the work-related problems of fisheries.

• 대한안전경영과학회지
• /
• 제8권6호
• /
• pp.13-27
• /
• 2006

The goal of this study is to propose the effective way of finding injurious factors and making improved plan that prevents the workers against musculoskeletal disorders at a semi-finished medical product fabricating company A questionnaire and an ergonomic assessment method were adopted to analyze the symptoms of workers' musculoskeletal disorders, and an analysis of working postures and a quantitative assessment on various processes were performed to find out harmful factors of workplace. Based on the result of the evaluation, to enhance the working environment, improvement of worktable, working space, tools, and outfit was suggested, and induction of mechanical system was also suggested. It can be concluded that the method and process described in this paper could be helpful for diagnosing the musculoskeletal disorders and making improvement plans to the company with similar working conditions and process.

• 한국안전학회지
• /
• 제31권5호
• /
• pp.49-53
• /
• 2016

The goal of this study is to analyze accidents occurred at experimental laboratory and to suggest hierarchical taxonomy applicable to prepare countermeasures reducing the experimental laboratory accidents. Recent 5 years accidents were analyzed and classified according to their primary cause, facility or human. Then in case of facility, the accidents were further classified whether they can be fixed by organization or by individual. In case of human factor, they were classified into physical, chemical, or biological to prepare precise measures. Depending on the adequacy of appropriate practice, several measures were suggested such as; whether to improve training of laboratory workers, or to improve training the system, or to improve or prepare practice substantially. A new taxonomy for laboratory accident was suggested complying other governmental agencies' classification such as KOSHA and KGS. Additionally, two kinds of possibilities were suggested such as possibility of major accident and possibility of disaster which can be defined as laboratory accident causing large scale of harmful consequence to residential area or environment by fire, explosion and/or toxic release of hazardous chemicals and/or microbiology.

• 한국기계가공학회지
• /
• 제10권4호
• /
• pp.82-87
• /
• 2011

Lubrication has an important role to reduce frictional forces and temperature between cutting chips and the face of a tool. However, it has harmful effects to workers' health and working environment. The purpose of this thesis is to find cutting conditions through the quality analysis in boring for SM45C steel using MQL(Minimum Quantity Lubrication). Machining process is super drill, tip drill, end mill and boring in order. Experimental factors of boring and the quantity of mist air are properly selected. With the analysis of experimental data, this thesis shows that boring with MQL improves the surface roughness when spindle speed is 934rpm or feeding speed is 74mm/min.