• 한국지반공학회논문집
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• 제19권3호
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• pp.5-13
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• 2003

쏘일네일링 공법은 작업공간의 확보가 용이하고 네일길이가 어스앵커보다 비교적 짧아 도심지 지하굴착에 매우 이로운 장점이 있다. 이 공법이 도입된 이후 쏘일네일링 벽체의 거동에 관한 연구는 토조에 의한 모형실험과 이론적 연구가 진행되고 있지만 지반조건이 다층토로 구성된 현장에 대한 연구는 미흡한 실정이다. 본 연구는 국내 다층토 지반에 시공된 쏘일네일링 현장에서 시공중 측정된 수평변위를 토대로 한 역해석적 방법에 의해 배면지반의 이완영역거리와 이완영역계수를 고찰하였다. 연구결과에 의하면 쏘일네일링 벽체 배면지반의 이완 영역거리는 최종굴착깊이의 증가에 따라 증가함을 보였으며, 그 비율은 최종굴착깊이의 94% 정도로 나타났다. 토사층과 암층이 혼합되어 있는 다층토 지반에서 토사층의 비율이 클수록 이완영역계수도 증가하였으나, 약 1.05값에서 수렴하는 경향을 나타냈다. 벽체 최대수평변위에 대한 지표면 최대수직변위와의 관계는 역해석결과에서 지표면 최대수직변위가 최대수평변위의 80%이하로 나타났으며, Caspe방법에 의한 지표면 최대수직변위는 최대수평변위의 150~280%의 범위로 나타나 역해석결과보다는 매우 큰 값을 나타내 Caspe방법이 매우 보수적임을 확인하였다.

• Safety and Health at Work
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• 제12권4호
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• pp.432-438
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• 2021

Background: We aimed to investigate the prevalence of low back pain (LBP) and its associated agricultural work-related, biomechanical factors among this population. Methods: We analyzed initial survey data from the Safety for Agricultural Injury of Farmers cohort study involving adult farmers in Jeju Island. The prevalence of LBP was calculated with associated factors. Results: In total, 1,209 participants were included in the analysis. The overall prevalence of LBP was 23.7%. Significant associations for LBP were the type of farming activity, length of farming career, prior agricultural injury within 1 year, and stress levels. Multivariate logistic regression analysis revealed three biomechanical factors significantly related to LBP: repetitive use of particular body parts; the inappropriate posture of the lower back and neck. Conclusions: Some occupational, and biomechanical risk factors contribute to LBP. Therefore, postural education, injury prevention education, and psychological support will be needed to prevent LBP.

• 한국언론정보학보
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• 제36권
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• pp.287-323
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• 2006

이 연구는 조직문화와 조직지원요소가 방송프로그램 제작단위인 팀 몰입에 영향을 주는 주요한 요소로 작용하고 있음을 실증적으로 분석하였다. 특히 조직문화 유형에 따라 조직지원요소 및 팀 몰입에 차별적인 영향을 미치고 있음을 구조방정식 모형을 이용해 밝혀내고자 하였다. 연구결과 조직문화 유형에 따라 조직지원요소 및 팀 몰입에 영향을 주는 경로 및 영향력에 차이가 있음을 확인할 수 있었다. 또한 보상평가요소를 제외하고는 교육훈련, 제작지원 등의 조직지원요소는 제작진의 몰입에 별다른 영향을 미치지 못했다. 이와 같은 결과는 방송 조직이 전략을 수립 집행함에 있어 제작진이 인식하고 있는 지배적인 조직문화 유형을 고려해야 보다 실효성을 높일 수 있음을 보여준 결과라 할 수 있다. 이밖에 현재의 교육훈련 프로그램과 제작지원 방식을 보완할 필요성이 있음을 확인할 수 있었다.

• 대한통합의학회지
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• 제2권1호
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• pp.109-116
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• 2014

Purpose : The purpose of this study was to perform the calf-raise exercise on the stable support surface and unstable support surface for comparing deference of the gastrocnemius thickness changes that measured by ultrasonography. Method : Subjects stand on unstable support surface and a stable support surface with both feet. Keeping calf-raise position in the 3 seconds, and then had to return back to the starting position. Total of 3 sets of 15 repetitions performed and give a 30-second rest between each set. In this way, exercise performed 3 times a week, performed a total of 6 weeks. Result : 1. gastrocnemius muscle thickness before and after exercise in experimental group A was significantly different(p<.05). 2. gastrocnemius muscle thickness before and after exercise in experimental group B was significantly different(p<.05). 3. gastrocnemius muscle thickness in experimental group A and experimental group B was significantly difference(p<.05). Conclusion : In conclusion, calf-raise exercise on unstable support surface was more efficient than stable support surface for increasing thickness of gastrocnemius.

• 대한임상전기생리학회지
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• 제5권2호
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• pp.73-84
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• 2007

This study aims to examine changes from differences in the lumbar scoliosis angle and iliac crest height due to abnormal and habitual posture shown in unilateral weight load at standing posture and suggest data for preventing and treating lumbago. The subjects of this study are 16 lumbago patients between twenties and forties with chronic lumbago over six months, but without neurological symptoms. As a result of photographing front and back with three conditions such as weight load on both sides and left or right unilateral weight load posture in order to examine changes of lumbar scoliosis and iliac crest according to changes of posture at unilateral weight load, while scoliosis angle and iliac crest height by habitual unilateral support were increased, those by opposite support were decreased. In conclusion, it was found that habitual unilateral weight load may cause continuous distortion of spinal angle and change of iliac crest height and these may be a factor of lumbago. Therefore, if habitual unilateral weight load state is kept continuously, distortion of lumbar angle and iliac crest height may be greater and common efforts to change habitual unilateral weight load are needed.

• 한국기계가공학회지
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• 제17권3호
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• pp.134-140
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• 2018

This paper describes the design and fabrication of an automatic alignment and loading system for workpieces. To move a workpiece to a chucking position of a machine tool using a gantry robot, an automatic aligning device is required to load the workpiece before machining and automatically align them. The automatic alignment system was conceptually designed, and the structural analysis was performed for the main parts such as the top plate, center support, front and back support, and support shaft. Based on the structural analysis results, the size of these structures was determined. The automatic alignment system was manufactured, and the vertical movement characteristics of the workpiece up-and-down movement device and the rotation characteristics of the workpiece rotation device were experimentally examined. The result has confirmed that they operate normally.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1141-1145
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• 2005

This paper proposes a robust tension control algorithm for the let-off and take-up system driven by servo motor which is robust to disturbance and tension variation by using SVR(Support Vector Regression). Quality of textile goods in fiber manufacturing process highly depends on control of let-off, take-up and tension which are essential for constant tension control of yarn and textile fabrics and correct length of them. The physical properties of textile fabrics are very sensitive to several factors(temperature, humidity, radius change of warp beam etc.) which result in tension change. Rapid development of fiber manufacture machine for higher productivity requires control system for let-off, take-up and tension for robustness to sharp tension-variation and quick response. The validity and the usefulness of the proposed algorithm are thoroughly verified through numerical simulation.

• 한국군사과학기술학회지
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• 제15권1호
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• pp.16-27
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• 2012

In multi-interface multi-channel(MIMC) based tactical ad hoc networks, QoS support for required operational capacity is one of the main challenging issues for multi-hop transmissions. To support QoS in such a harsh environment, we propose a novel MAC scheme to minimize multi-hop as well as per-hop delay. The current IEEE 802.11 MAC protocols should contend to reserve the channel resource at every hop by each sender. The every-hop channel contention results in a degradation of end-to-end delay for multi-hop transmissions. The basic idea of our scheme is to make a "multi-hop reservation" at the MAC layer by using the modified RTS frame. It contains additional information such as destination information, packet priority, and hop count, etc. In addition, we differentiate the contention window area according to the packet priority and the number of hops to deliver packets in the predefined allowed latency. Our scheme can minimize the multi-hop delay and support the QoS of the critical data in real time(i.e., VoIP, sensing video data, Video conference between commanders). Our simulation study and numerical analysis show that the proposed scheme outperforms the IEEE 802.11 MAC.

• Geomechanics and Engineering
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• 제12권3호
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• pp.483-503
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• 2017

Uncertainty is a fact belonging to engineering practice. An important uncertainty that sets geotechnical engineering is the variability associated with the properties of soils or, more precisely, the characterization of soil profiles. The reason is due largely to the complex and varied natural processes associated with the formation of soil. Spatial variability analysis for the study of the stability of natural slopes, complementing conventional analyses, is able to incorporate these uncertainties. In this paper the characterization is performed in back-analysis for a case of landslide occurred to verify afterwards the presence of the conditions of shear strength at failure. This approach may support designers to make more accurate estimates regarding slope failure responding, more consciously, to the legislation dispositions about slope stability evaluation and future design. By applying different kriging techniques used for spatial analysis it has been possible to perform a 3D-slope reconstruction. The predictive analysis and the areal mapping of the soil mechanical characteristics would support the definition of priority interventions in the zones characterized by more critical values as well as slope potential instability. This tool of analysis aims to support decision-making by directing project planning through the efficient allocation of available resources.

• 대한산업공학회지
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• 제25권4호
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• pp.459-465
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• 1999

A new-concept VDT workstation chair with adjustable keyboard/mouse support was proposed to minimize physical discomfort and the risk of cumulative trauma disorders (CTDs) at work sites in this study. First, a three-dimensional human modeling tool $(SAFEWORK^{(R)})$ was used to design the new chair satisfying the anthropometric specifications of Korean population. Second, based upon the result of 3-D graphical simulation, a mock-up chair was constructed with an adjustable keyboard/mouse support directly attached to the chair body. Third, muscle fatigue and subjective discomfort were measured to evaluate the newly developed chair. An experiment was conducted to compare the new workstation chair to the traditional computer chair without keyboard/mouse support. Six volunteer subjects participated in six one-hour word-processing sessions with two different chairs and three different postures. Statistical results indicate that the new-concept VDT chair generally improved subjective comfort level and reduced fatigue in finger flexor/extensor and low back muscle. In conclusion, this new VDT workstation chair is expected to reduce physical discomfort and prevent occupational CTD problems in the long run. Implications of the new design and suggestions for the further development are also addressed.