• 한국지반환경공학회 논문집
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• 제21권6호
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• pp.19-25
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• 2020

최근 도심지 공사에 있어서는 공간부족 및 주변환경의 영향으로 기성파일의 시공이 불가능한 경우가 많다. 이러한 경우에 소형 장비로 시공이 가능하고 기존 파일의 지지능력을 발휘할 수 있는 소구경 파일 공법이 많이 사용되고 있다. 소구경 파일공법은 현장타설말뚝의 한 종류로서 파일의 직경이 75mm~300mm인 정도로 주변 구조물이나 지반 그리고 공간적인 장애물이 있는 경우에도 시공의 어려움이 거의 없으며 모든 종류의 토질조건에서 시공이 가능하다. 또한 시공과정에서 진동과 소음이 적고 건물 천장이 낮은 곳에서도 시공이 가능하므로 기존 건물의 기초보강에도 많이 이용된다. 이러한 마이크로파일이 압축력이나 인장력을 받았을 때 혹은 시공된 지반특성에 따라 변화되는 거동 특성에 대해서는 연구가 많지 않은 실정이다. 따라서 이 연구에서는 현장에 시공된 마이크로파일에 대한 현장재하시험 자료 분석을 통하여 마이크로 파일에 압축력 및 인장력을 가했을 경우 지반을 구성하는 성분과 파일의 근입조건에 따른 침하 및 지지력 특성을 규명하고 통계분석프로그램인 SAS를 활용하여 마이크로파일의 침하와 지지력에 영향을 미치는 주요한 인자에 대한 분석을 수행하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.595-609
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• 2020

In this study, we propose a decentralized mathematical model for predictive control of a system of multi-autonomous unmanned aerial vehicles (UAVs), also known as drones. Being decentralized and autonomous implies that all members make their own decisions and fly depending on the dynamic information received from other unmanned aircraft in the area. We consider a variety of realistic characteristics, including time delay and communication locality. For this flocking flight, we do not possess control for central data processing or control over each UAV, as each UAV runs its collision avoidance algorithm by itself. The main contribution of this work is a mathematical model for stable group flight even in adverse weather conditions (e.g., heavy wind, rain, etc.) by adding Gaussian noise. Two of our proposed variance control algorithms are presented in this work. One is based on a simple biological imitation from statistical physical modeling, which mimics animal group behavior; the other is an algorithm for cooperatively tracking an object, which aligns the velocities of neighboring agents corresponding to each other. We demonstrate the stability of the control algorithm and its applicability in autonomous multi-drone systems using numerical simulations.

• 한국안전학회지
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• 제20권4호
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• pp.97-105
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• 2005

As construction project is becoming larger, construction progress and works are more various and complex according to recent Korean construction tendency. The growth of construction induces much pollution on the progress of construction and the problems due to the construction pollution are raised into social problem strongly, because it is increasing the need on the quality of lift and the desire of clean environment. This study aimed to seek far the effective solving plan of the construction popular complaints by surveying the real condition of construction popular complaints and analyzing the cause and tansaction period of popular complaints. For this study, the laws related and popular complaints were analysed focusing on the documents in low district offices of Gwangju from 2000 to 2004. As a result, the types of construction popular complaints were divided into 17 and the causes were as follows in order: crack and subsidence of ground(14.90%), infringement of private life(11.55%), noise(10.80%), infringement of a right to sunshine(10.07%) and breakdown(6.7%). Consequently, it is considered that these complaints are occurred by physical and environmental causes.

• 도시과학
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• 제10권1호
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• pp.29-37
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• 2021

The number of old buildings older than 30 years in Korea continues to increase from 29.9% in 2005 to 38.8% in 2020. Considering the growing urban regeneration projects, urban maintenance projects, the suppression of urban expansion, and the lack of idle land in the city, the dismantling of old buildings is expected to increase further in the future. As major accidents at building dismantling sites continue to occur, related agencies are also strengthening safety management of building dismantling works. While physical safety management such as collapse and fall is strengthened, there is a relative lack of interest in the health of workers at dismantling sites due to environmental hazards. Since relevant laws stipulate that construction waste should be separated and discharged, old buildings need to be considered for environmental hazards such as fine dust, floating bacteria, and floating molds when dismantling. In this study, we intend to find important safety management elements in the management of building dismantling sites, measure environmental factors harmful to dismantling workers, and present basic data for the management of dismantling sites in the future. "Safety management" was the highest priority, followed by "dust," "vibration," "noise," "bacteria," and "smell." The perception of the importance of "physical damage prevention" with workers working on dismantling and managers managing the site came out similar, but the perception of "work efficiency" and "health disorder prevention" through environmental hazard management showed different priorities. In the process of dismantling, floating bacteria and floating mold were collected, cultured, and measured the concentration in the indoor air. The measurement was measured by dividing it into pre-dismantling and during dismantling.

• International Journal of Safety
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• 제4권2호
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• pp.43-46
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• 2005

The construction workers might be at the risk of many occupational injuries and illnesses. To protect workers from various hazards, industrial health and hygiene systems were specified for the construction workers by law. It is important to know the actual health and safety(H&S) conditions by tasks and the characteristics of injuries and illnesses of construction workers. This study was designed to investigate the actual conditions of construction workers exposed to various harmful substances and work elements including evaluation of health status of each worker and general H&S system. Questionnaire was sent to 600 construction workers nationwide and totally 367 people responded to it having 61.67% of response rate. The common construction hazards were dust(29.6%), noise(19.3%), repetitive motions(12.0%), handling excessive heavy materials(11.2%) in order. The repetitive motions and handling heavy materials related to muscle disorders accounted for 23.2%. The accident and injury types were in order of overexertion, falling, overturning, dropping or flying, electric shock, collision, etc.

• 한국안전학회지
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• 제31권4호
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• pp.22-26
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• 2016

"Always-on" small ventilators are likely to experience thermal decomposition of insulating material due to thermal, electrical, mechanical and environmental influences, and lose insulating properties by the process of oxidation and physiochemical reaction. This increases the risk of electrical fire because of layer short, short circuit, overload and Plastics are usually used to make ventilator and ventilator enclosures since they make less noise and are cheaper. Although more preferred than iron, plastic, a combustible material, has a higher risk of fire. In this study, several experiments were carried out to find out how RCD(Residual Current Protective Device) and Thermal fuses, which are electric motor protection devices, work and what needs to be done to reduce the risk of fire.

• 한국가정과학회지
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• 제9권2호
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• pp.5-20
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• 2006

This study was a preliminary investigation into improving the environmental and healthy quality of childcare centers. The purpose of this study was to determine the management condition on indoor environment and hygiene of childcare centers in Cheongju. Questionnaire survey was carried out from 11st to 26th of August 2004 by mail. Respondents were consisting of 55 teachers, an executive of each childcare center in Cheongju. From the survey results, there were some problems in 'empty period after remodeling work for preventing sick house syndrome', 'humidity controling', 'glare controling', 'indoor or outdoor noise controling', 'cleaning frequency of each room', 'washing method of toys', 'laundry frequency of rag doll and bedclothes'. So, we need to establish the regulations or give some educations and informations about indoor environment and hygiene to administrators of childcare centers.

• 항공우주시스템공학회지
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• 제2권2호
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• pp.1-7
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• 2008

Recently the wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuel due to its lack and environmental issues. This work is to propose a structural design and analysis procedure for development of the low noise 100W class small wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. Structural analysis including load cases, stress, deformation, buckling, vibration and fatigue life was performed using the Finite Element Method, the load spectrum analysis and the Miner rule. In order to evaluate the designed structure, the structural test was carried out and its test results were compared with the estimated results. In addition, the blade should be safe from the impact damage due to FOD(Foreign Object Damage) including the bird strike. In order to analize the bird strike penomena on the blade, MSC. Dytran was used, and the applied method Arbitrary Lagrangian-Eulerian was evalud by comparison with the previous study results.

• Structural Engineering and Mechanics
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• 제73권1호
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• pp.27-35
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• 2020

In rail industry, noise reduction is a concern to decrease environmental pollution. The current study focuses on rail damper modeling and improvement of the model through validation with experimental results. Accurate modeling and simulation of rail dampers, specifically tuned rail dampers with layers interconnected by bolt joints, shall enable objective-oriented improvement of their design. In this work, to improve the damper model cone pressure theory is applied in the FE model and the sensitivity analysis is then applied to gradually improve the FE model. The improved model yields higher Modal Assurance Criterion (MAC) values and lower frequencies deviation.

• 한국산업보건학회지
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• 제16권4호
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• pp.364-374
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• 2006

Natural ventilation technique could be the substitute for or the complement to the local exhaust ventilation system in the sense of protecting work environment. Moreover, it has many strong points ; almost no mechanical parts, no energy use and no noise. If applied appropriately, it could have the very high ventilation rate and save a lot of energy expense. But, it depends on the outdoor environment, especially temperature and wind speed/direction. Predicting the capacity of natural ventilation is not an easy job because it comes from both buoyancy and wind effect. Another problem is too much flow through the ventilator especially in winter time due to too much difference between indoor and outdoor temperature. Thus some ventilators in industries are sealed by door or plastic sheet, resulting in bad work environment. Various types of dampers are used to control the flow rate through ventilators. The capabilities of flow control by damper has not been estimated. In addition, it was not tested whether the damper could obstruct the flow through ventilator when fully opened. To answer these questions, 4 types of dampers were tested by using computational fluid dynamics. 10 different configurations includes no damper, full open and half open. Flow rates were estimated and airflow fields were analysed to clarify the before-mentioned questions. The dual type damper was the best choice for controling the capability of ventilator. In addition, the upward grill type damper was the best for not obstructing the air flow when fully opened.