• 현장농수산연구지
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• 제10권1호
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• pp.101-111
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• 2008

As the quality of life improves, people want to live in more pleasant environment with beautiful trees, clean air and water. They are keenly interested in environmental issues as well as living environment of apartment which is a trademark of modern life. With this situation, the function and roles of landscaping trees have been recognized as a critical factor to improve living environment. As people have asked for more demands on those trees, it has raised more issues on the defect of trees and is required the solution to those issues. So, the purpose of this study was to survey the reasons of defects and find out those solutions. The data on defects in 1990s was referenced to the reports issued by SH Corporation in 1994 and 1997. The data on defects in 2000s are collected from March, 2006 to May 2006 based on the survey for apartments already constructed by Korea Housing Corporation. The results of the survey were shown that, in the year of 1994, landscaping trees causing high rate of defects were Acer buergerianum (92%), Pinus densiflora(85.7%), Celtis sinensis(80%), Cydonia sinensis(75%) and Diospyros kaki(66.6%), and in the year of 1997, landscaping trees causing high rate of defect were Ziziphus jujuba(100%), Cornus alba(65.2%), Diospyros kaki(60%), Thuja occidentalis(60%), and Metasequoia glyptostroboides(42%). And, in the year of 2006, landscaping trees causing high rate of defect were Sophora japonica(100%), Taxus cuspidata(80%), Magnoila quinquepeta (75%), Acer palmatum(62.5%) and Ginkgo biloba(50%). Because the reasons of defects were various according to the conditions including the climate, location, time and landscaping trees carried into the work area, we present the problems and solutions to those defects. Since the landscaping trees are living creatures, the factors of defects were various and complicated according to the site condition. So, in the period of warranty, contractor should designate the tree manger who can recognize the situation and take suitable action within timely manner.

• 한국산업보건학회지
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• 제33권3호
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• pp.317-331
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• 2023

Objectives: Construction workers are exposed to various hazardous substances simultaneously. However, little is known about the exposure hazards in construction industry. This study was aimed at identifying the risk of exposure hazards among construction workers. Methods: The expert survey (n=29) was conducted, including construction industry health managers (n=11) and work environment monitoring experts (n=18), on exposure probability, intensity and risk of hazardous substances by construction occupations Results: The exposure hazards of 30 construction occupations were identified and summarized through a literature review and expert survey. The most prevalent hazards were in order of noise, awkward posture, heat/cold, crystalline silica, cement/concrete dust, metal fumes, and volatile organic compounds. The hazards with highest risk score(over seven points) at construction occupations were noise(formwork carpenter, concrete finisher, rebar worker, demolition worker, driller/rock blaster), hazardous rays(welder), heat/cold (earthworks, formwork carpenter, rebar worker, concrete placer, scaffolder), awkward posture(bricklayer, caulker/tile setter, rebar worker) and heavy lifting(bricklayer, rebar worker). Among construction workers, the job types with the highest risk of exposure to carcinogens, and in which occupational cancer has been reported, were in order of stonemason, concrete finisher, rock blaster, welder, insulation installer, painter, scaffolder, plant worker and earthworks in order Conclusions: Systematic research and discussion on occupational disease among construction workers and its various hazardous factors are needed to establish job exposure matrix for facilitating standard for promptly processing the workers' compensation.

• Computers and Concrete
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• 제33권1호
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• pp.27-39
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• 2024

In this study, the authors investigate the free vibration behavior of three-phases functionally graded sandwich plates using a novel nth-order shear deformation theory. These plates are composed of a homogeneous core and two face-sheet layers made of different functionally graded materials. This is the novel type of the sandwich structures that can be applied in many fields of mechanical engineering and industrial. The proposed theory only requires four unknown displacement functions, and the transverse displacement does not need to be separated into bending and shear parts, simplifying the theory. One noteworthy feature of the proposed theory is its ability to capture the parabolic distribution of transverse shear strains and stresses throughout the plate's thickness while ensuring zero values on the two free surfaces. By eliminating the need for shear correction factors, the theory further enhances computational efficiency. Equations of motion are established using Hamilton's principle and solved via Navier's solution. The accuracy and efficiency of the proposed theory are verified by comparing results with available solutions. The authors then use the proposed theory to investigate the free vibration characteristics of three-phases functionally graded sandwich plates, considering the effects of parameters such as aspect ratio, side-to-thickness ratio, skin-core-skin thicknesses, and power-law indexes. Through careful analysis of the free vibration behavior of three-phases functionally graded sandwich plates, the work highlighted the significant roles played by individual material ingredients in influencing their frequencies.

• Safety and Health at Work
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• 제15권1호
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• pp.59-65
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• 2024

Background: Different job strain formulations based on the Job Demand-Control model have been developed. This study evaluated longitudinal associations between job strain and psychological distress and whether associations were influenced by six formulations of job strain, including quadrant (original and simplified), subtraction, quotient, logarithm quotient, and quartile based on quotient, in randomly selected Japanese workers. Methods: Data were from waves I and II of the Survey of Midlife in Japan (MIDJA), with a 4-year followup period. The study sample consisted of 412 participants working at baseline and had complete data on variables of interest. Associations between job strain at baseline and psychological distress at follow-up were assessed via multivariable linear regression, and results were expressed as β coefficients and 95% confidence intervals including R² and Akaike information criterion (AIC) evaluation. Results: Crude models revealed that job strain formulations explained 6.93-10.30% of variance. The AIC ranged from 1475.87 to 1489.12. After accounting for sociodemographic and behavioral factors and psychological distress at baseline, fully-adjusted models indicated significant associations between all job strain formulations at baseline and psychological distress at follow-up: original quadrant (β: 1.16, 95% CI: 0.12, 2.21), simplified quadrant (β: 1.01, 95% CI: 0.18, 1.85), subtraction (β: 0.39, 95% CI: 0.09, 0.70), quotient (β: 0.37, 95% CI: 0.08, 0.67), logarithm quotient (β: 0.42, 95% CI: 0.12, 0.72), and quartile based on quotient (β: 1.22, 95% CI: 0.36, 2.08). Conclusion: Six job strain formulations showed robust predictive power regarding psychological distress over 4 years among Japanese workers.

• Wind and Structures
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• 제39권3호
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• pp.223-242
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• 2024

Wind comfort in cold climates is one of the most essential factors for urban planners. This issue is particularly important for sidewalks that are in line with the prevailing wind flow and surrounded by high-rise buildings. Imam Street near the University Square in Tabriz is one of the passages that struggle with uncomfortable wind speeds. The aim of this study is to investigate the role of sidewalk walls on pedestrian wind comfort. These multifunctional walls not only serve as street furniture, but also reduce wind speed at pedestrian level. In this work, all simulations are performed using the RWIND tool and validated by wind tunnel experiments at the Architectural Institute of Japan. The main objective of this study is to evaluate the effects of the angle, height and spacing of the walls on wind attenuation at pedestrian level. The results show the effect of multifunctional walls on pedestrian-level wind mitigation. By rotating the windbreak walls from 0 to 60 degrees along the street, the average wind speed decreases by 30% to 46% compared to a situation without this type of wall. Increasing the wall height from 1.5 to 2 meters reduces the urban wind speed by 39-46%. However, increasing the distance between the sidewalk walls from 3.5-9.5 meters reduces the speed in the models from 46% to 32.7%. Finally, it has been demonstrated that sidewalk walls with a height of 2 meters, a rotation angle of 60° and a distance of 3.5 meters are the optimal choice for wind attenuation at pedestrian level.

• 대한토목학회논문집
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• 제44권4호
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• pp.555-565
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• 2024

정부에서는 건설폐기물의 재활용을 높이기 위해서 분별해체를 강제하기 위해 법률규정을 제정하였다. 따라서 본 연구는 대규모 택지 조성을 위한 분별해체 공사의 공사비 산정을 위한 필수적인 요소로서 원단위를 제안하는 것을 목표로 한다. 이를 위해 4채의 단독주택을 선정하고 현장 조사와 실험을 하였다. 주택을 실측하여 도면을 작성하고 내장재를 정밀 조사하여 분별해체 작업의 공사비 산정을 위한 원단위를 제안하였다. 분별해체 작업은 천장, 벽, 바닥 등으로 부위별로 구분하여 진행하였고 부위별, 재료별로 작업 시간을 측정하였다. 특히 벽의 개구부를 구성하는 창문 등에 대한 보정 작업을 시행하여 기존 연구와의 차별성을 확보하고 정확성을 향상했다. 이러한 연구 결과는 실무에 즉시 적용할 수 있는 구체적인 지침으로 활용될 것으로 기대되며, 건설 분야의 지속 가능한 발전을 촉진할 것으로 기대된다.

• 정보처리학회 논문지
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• 제13권9호
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• pp.468-473
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• 2024

도심 지역에서의 굴착 작업은 지반 변형을 유발할 수 있으며, 이는 인근 인프라에 피해를 줄 수 있다. 지반 변형으로 인해 작업 현장 근처의 보도블록에 변위가 발생할 수 있다. 변위를 정확하게 측정하여 지반 변형의 잠재적인 위험을 평가하는 지표로 사용할 수 있다. 본 논문에서는 UGV에 장착된 3D 레이저 라인 센서를 이용한 강건하고 효율적인 보도블록 이격 측정 방법을 제안한다. 제안 방법은 2D 투영 기반 객체 탐지와 CPLF 알고리즘을 통한 측정의 두 단계로 구성된다. 실험 결과, CPLF 알고리즘이 PLF에 비해 효율적임을 확인했으며, CPLF 알고리즘이 1.36 mm의 오차와 10.76ms의 처리 시간을 보여 제안 방법이 다양한 유형의 보도블록과 환경적 요인이 존재하는 실제 환경에서도 UGV에서 3D 레이저 라인센서를 이용하여 강건한 온라인 측정을 보장하면서도 높은 정확성을 유지할 수 있음을 확인했다.

• 한국산업보건학회지
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• 제27권4호
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• pp.302-312
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• 2017

Objectives: In this study, an evaluation of the working environment of furnace workers was performed and the work-relatedness of the occupational diseases were examined Methods: In this study, two electric furnaces at a single casting business site producing manganese-based iron alloy were selected, and occupational exposures to hazardous substances were evaluated for furnace workers and furnace worker assistants. Results: As a result, total dust concentration were $0.407{\sim}3.001mg/m^3$ and respirable dust concentration were $0.196{\sim}0.584mg/m^3$. The highest concentration of crystalline silica was $0.079mg/m^3$ In the case of Masato and Sosuckwhoi crystalline silica, they contained 90.85% and 4.17% respectively. Manganese concentration was the highest at a $0.205mg/m^3$ maximum. The average of black carbon is $11.56{\mu}g/m^3$ and the maximum concentration is $604.23{\mu}g/m^3$. PAHs concentration was the highest at a $78.301{\mu}g/m^3$ of naphthalene. The concentration of carbon monoxide was 18.82 ppm(total average 3.89 ppm) during pouring, and the maximum is 131 ppm. The formaldehyde concentration was 0.003 to 0.007 ppm. Conclusions: It seems that conditions in the past were worse, since casting has recently been performed only twice per day for about 20 minutes, reducing the amount of pouring, and local exhaust systems have been installed one-by-one. In addition, it was judged that the past exposure levels were higher considering the points measured on the back-side due to the risk of damage to the individual samples. It was found that operators could be exposed to high concentrations of crystalline silica, and that they were also exposed to high concentrations of metal(fume) and carbon monoxide during pouring. Therefore, there is a risk that occupational diseases such as lung cancer and COPD may occur with long-term work in such a process.

• 한국건설관리학회논문집
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• 제13권1호
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• pp.106-117
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• 2012

최근 국내에서 정착되고 있는 철근 공장가공은 절단손실 감소, 정밀도 향상 등의 장점과 도심지공사 증가, 숙련공 감소 등의 외부 요인으로 향후 비중이 증가할 것으로 예상된다. 그러나 공장가공을 하더라도 정척철근 (Straight rebar)을 사용하면 손실 발생 및 그로 인한 CO2배출 같은 환경 문제가 발생할 수밖에 없다. 이를 해결하기 위한 대안의 일환으로 코일철근(Bar in coil) 도입이 제안되었으나, 코일철근은 국내 미생산, 고가의 장비비 등의 이유로 국내 적용이 거의 전무하다. 또한 코일철근은 완전 자동화에 가까운 방식으로 가공되기 때문에 향후 높은 손실저감률과 가품질이 우수하여 국내 적용이 확대될 것으로 예상되나, 적용타당성 분석에 대한 연구가 부족한 실정이다. 따라서 본 연구에서는 최근 국내 생산이 시작된 코일철근의 특성과 코일철근 도입이 철근가공 산업에 미치는 영향을 분석, 철근가공 산업 선진화를 위한 기초연구로서 진행한다. 이를 위해 국내 철근가공 산업의 현황을 조사하고, 코일철근 도입시 산업적 측면에서 적용성과 경제적 측면에서 이해관계자의 손익 타당성을 분석하고 향후 연구방향을 제시한다.

• 서비스연구
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• 제7권4호
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• pp.83-107
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• 2017

본 연구는 맥락 특화적인 서번트 리더십의 제안을 목적으로 항공운수서비스 업종의 승무원 직종을 대상으로 서번트 리더십이 하위직급 리더(사무장)에 대한 부하의 신뢰와 직무몰입에 미치는 영향을 분석하였다. 회귀분석의 결과, 리더신뢰에 대해서는 청지기정신 차원에서 리더 자신이 희생을 보이는 일, 부하들의 의견을 적극 반영하는 일이 영향력을 행사하였다. 공동체형성 차원에서는 협력을 통하여 일하는 것과 원칙 규칙을 지키는 일, 리더가 보상을 추구하지 않는 것, 부하에게 필요한 권한을 주는 것이 유의한 영향을 끼쳤다. 직무몰입에 대해서는 청지기정신 차원에서 부하가 성장할 수 있도록 돕는 일과 리더가 도전적으로 업무에 임하는 것이 유의한 영향력을 행사하였다. 공동체형성의 항목 중에는 리더가 보상을 추구하지 않는 것과 원칙 규칙을 지키는 일이 부하의 직무몰입을 조성하는 것으로 나왔다. 이러한 결과를 바탕으로 본 연구는 기업의 인사책임자에게 재래의 리더십프로그램을 지양하고, 기업이 처한 맥락에 맞는 맞춤형 인재의 선발과 훈련을 제안한다.