• 한국해양공학회지
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• 제25권6호
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• pp.86-90
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• 2011

The mining of imitated manganese noodles in 1000 m of seawater is planned for 2012. Thus, it is necessary to prepare the lifting pipes to be used for the test. Because of storage and expense constraints, flexible and economic HDPE pipe is being considered, making it necessary to test the structural safety. Material, pressure-chamber tests and finite element analysis of HDPE pipe for the 1000-m depth were performed. The tangential stiffness of HDPE was obtained through tension and three-point bending material tests and used for a structural analysis. FEA results show that the current sample pipe segment is safe for 1000 m of water pressure, and the stress result is also within the safe value. From the current results, the HDPE pipe seems to be acceptable only for the currently suggested constraints. However, more numerical and pressure tests need to be considered by applying additional physical conditions such as gravitational and hydrodynamic loads, external and internal fluid pressure, axial force induced ship motion, and heavy pump pressure to determine future usage.

• 한국해양공학회지
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• 제25권4호
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• pp.1-6
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• 2011

The installation of a topside structure can be categorized into the following stages: start, pre-lifting, lifting, lifted, rotating, positioning, lowering, mating, and end of installation. The transfer of the module onto the floating spar hull occurs in the last three stages, from lowering to the end. The coupled multi-body motions are calculated in both calm water and in irregular waves with a significant wave height (1.52m). The effects of the hydrodynamic interactions between the heavy lifting vessel and the spar hull during the lowering and mating stages are considered. The internal forces caused by the load transfer and ballasting are derived for the mating phases. The results of the internal forces for the calm water condition are compared with those in the irregular sea condition. Although the effect of the pitch motion on the relative vertical motion between the deck of the floating structure and the topside module is significant in the mating phases, the internal force induced pitch motion is too small to have this influence. However, the effect of the internal force on the wave-induced heave responses in the mating phases is noticeable in the irregular sea condition because transfer mass-induced draught changes for the floating structure are observed to have higher amplitudes than the external force induced responses. The impacts of the module on the spar hull in the mating phase are investigated.

• KIEAE Journal
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• 제7권6호
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• pp.99-106
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• 2007

Tower crane is a large construction equipment which is extremely tall for its section when it is erected, with its high slenderness ratio, and it has a heavy load by itself due to large lifting stuff to handle. In line with the construction projects in these days which increasingly tend to become higher, larger and complex, the stuff and height subject to lifting are also getting larger and higher, which has also increased the risk of disastrous accidents. A stable foundation design thus to deal with the increasing self load becomes more important. When a typhoon Maemi swept the nation in 2003, as many as 43 tower cranes fell down or collapsed, causing a severe damage to the people and the properties. Considering such fatal damages, a technical evaluation of the stability to prevent the safety accident with the tower crane must be very crucial. Tower cranes operation in domestic construction sites, in fact, have been simply dependent on personal experience and intuition of the engineers. Particularly when it comes to the foundation design, it mostly depends on manufacturer's recommendation. The study hence was intended to develop the fundamental measures for granting the objective stability, instead of following the individual's experience only. The simulation model recommended in the study is expected to make a good commitment to achieving an effective lifting work as well as preventing the safety accident.

• 한국안전학회지
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• 제21권4호
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• pp.108-113
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• 2006

The Work-Related Musculoskeletal Disorders(WMSDs) have been an rising issue since the 1970s. So many manufacturing companies have been tried to improve the work environments for the control and the prevention of the WMSDs. Specific risk factors associated with WMSDs include repetitive motion, heavy lifting, forceful exertion, contact stress, vibration, awkward posture and rapid hand and wrist movement. But recently it has reported that besides working conditions, job stress is the important hazard causes which lead to WMSDs. This study investigates the relation between WMSDs and Job stress from 1426 workers in Heavy Industry. Job stress was evaluated by Karasek's model. Job stress was associated with job satisfaction. Job demand was associated with the WMSDs, but job control was not associated with the WMSDs. The results can be used to design the management program for the WMSDs and the job stress.

• 대기
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• 제18권4호
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• pp.367-386
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• 2008

The Weather Research and Forecasting (WRF) model was designed to identify the role of the Taebaek Mountains in the occurrence of heavy snowfall in Yeongdong area with a strong northeast wind on January 20-21, 2008. To this end, in addition to the control simulation with the realistic distribution of the Taebaek Mountains, a sensitivity experiment that removed the orography over the Taebaek Mountains was performed. The control simulation results showed that the resulting wind field and precipitation distribution were similar to what were observed. Results from the sensitivity experiment clearly demonstrates the presence of orographic lifting on the windward slope of the mountains. It is concluded that the altitude of the Taebaek Mountains is the main controlling factor in determining the distribution and amount of precipitation in the Yeongdong area for the case of heavy snowfall in January 2008.

• 한국기계가공학회지
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• 제18권5호
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• pp.23-28
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• 2019

In recent years, medium- to large-scale transportation machinery and machine tool manufacturing process lines have shown a trend toward centralization, softening, lightening, and slimming to reduce costs and increase productivity. This has increased the demand for vertical articulated robots. When developing and introducing a heavy weight-handling robot that can be easily applied to existing production lines, it is expected to have a great effect in securing industrial competitiveness by solving industrial issues such as the decreased productivity and increased risk of accidents due to work involving heavy lifting. In this study, we design a 6-axis robot mechanism with a heavy load-handling capacity of 700kg or more for large-sized materials of various types supplied in small quantities.

• 한국화재소방학회논문지
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• 제27권3호
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• pp.85-93
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• 2013

본 연구에서는 소방대원이 수행하는 업무 중 중량물을 다루어야 하는 작업에 대한 분류 및 정량적 분석(NLE, 3DSSPP)을 수행하여 향후 소방대원의 중량물 관련 작업에 대한 위험도를 예측하고, 관련 위험도를 감소시키기 위한 기초 자료를 도출하고자 하였다. 도출된 위험도 등급은 위험도 점수가 3점부터 9점까지 총 7단계로 구성되었다. 가장 위험도가 높은 1등급은 나타나지 않았으며 인명구조 작업이 두 번째로 높은 2등급에 속하는 것으로 나타났다. 3등급은 파괴기구 활용, 환자 들어올리기작업 등으로 나타났다. 본 연구 결과들은 소방대원의 허리 부상을 포함하는 근골격계 질환 예방을 위한 작업방법 및 장비의 개선, 교육 프로그램의 개발에 기본 토대가 될 수 있다고 판단되며, 소방대원들의 근골격계 질환에 대한 지속적인 예방을 위해서는 본 연구의 골격을 토대로 한 추후 심층적인 조사와 연구가 시급하다고 사료된다.

• 한국콘텐츠학회논문지
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• 제15권8호
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• pp.46-52
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• 2015

공연장의 거대한 무대 세트나 장치에 움직임이 부여되면, 다양한 극적 효과를 연출할 수 있다. 본 논문에서 제안하는 프로그래밍 가능한 다축 체인 호이스트 서버 시스템은 이러한 연출의 자동화를 가능하게 한다. 본 시스템에는 PTP 기반의 임의 궤적 생성 방법, 다축 실시간 통신 제어 방법, 그리고 4 단계의 순차적인 안전 진단 알고리즘이 적용 되었으며, 호이스트들은 콘솔의 동기 제어에 의하여 시나리오의 연출 순서에 따라 자동적으로 움직인다. 12대 체인호이스트로 구성된 멀티 체인 호이스트 서버 시스템에 대한 1 ton 부하 및 대칭-비대칭 배치 부하에 대한 실험을 통해서 우수성을 검증하였다. 아울러 K-POP 공연에서 극적효과를 연출하는데 성공적으로 적용되었다.

• 지역사회간호학회지
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• 제12권2호
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• pp.504-512
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• 2001

For the purpose of grasping the actual condition of low back pain in women workers, 166 women in two neighboring factories were studied using questionnaire, 60% of the workers complained of low back pain. and 63% of them responded that their low back pain come from their job. About the severity, 77% marked the moderate, and 15% said absences owing to the pain. But 60% of them have not sought medical help. The low back pain occurred mainly in the workers of sitting posture and in the workers of treating heavy objects. And the workers who have worked over three years are dominant(44%) in the pain group. Comparing the pain group with the non-pain group, two variables - whether the worker treats heavy materials or not, and how heavy the materials are - showed statistically significant differences. So. there must be concern over the low back pain of women workers. In operation allocation. treating heavy objects and lifting up should be carefully considered. And for the prevention of low back pain. the workers need education and pain exercise.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.472-478
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• 2004

This paper describes the characteristics of the unsteady pressure on the stator surface induced by rotor viscous wakes. The primary object of this study is to investigate the effects of axial spacing between the rotor and the stator and three-dimensional vane geometries such as stator sweep and stator lean on the unsteady pressure fluctuations on the stator vane. To predict these fluctuations, unsteady three-dimensional Navier-Stokes analyses are performed. Furthermore, a three-dimensional analytical method using unsteady lifting-surface theory is also used to elucidate the mechanism of interaction of passing rotor wakes with downstream stator. Five different fan configurations with three sets of stator geometries, which are three radial stator configurations with different axial spacing, the swept stator and the swept and leaned stator, are used for this study. It is found that, in axial spacing between rotor and stator, the effect of radial phase skew of incoming rotor wake is important for the reduction of the induced unsteady pressure in addition to the rotor wake decay. It is also shown that incorporation of stator sweep and lean is effective to reduce this unsteady pressure.