• Composites Research
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• 제25권1호
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• pp.19-25
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• 2012

본 연구에서는 압축하중을 받는 원공을 가진 샌드위치 복합재 기둥의 좌굴 거동을 조사하였다. 샌드위치 복합재 기둥은 유리섬유직물/에폭시 면재와 우레탄 폼 심재로 구성되어 있다. 이때 면재 두께는 1.7mm, 심재 두께는 23mm, 37mm, 48mm, 61mm, 그리고 원공 직경은 25mm와 38mm를 고려하였다. 원공 위치가 샌드위치 복합재 기둥의 좌굴 거동에 미치는 영향을 조사하기 위해 직경 25mm인 원공이 시편중앙부에 있는 경우, 시편중앙부를 기준으로 중앙부와 끝단 사이의 1/4 지점에 있는 경우, 시편중앙부를 기준으로 중앙부와 끝단 사이의 1/2 지점에 있는 경우를 고려하였다. 시편중앙부에 직경 25mm인 원공이 있는 경우의 좌굴하중과 최대하중은 원공이 없는 경우보다 10% 정도 낮게 나타나며, 시편중앙부에 직경 38mm인 원공이 있는 경우의 좌굴하중과 최대하중은 원공이 없는 경우보다 30% 정도 낮게 나타났다. 그러나 원공 위치가 좌굴하중과 최대하중에 미치는 영향은 크지 않았다. 주요 파괴 모드는 심재 두께가 23mm와 37mm와 같이 얇은 경우는 심재 전단파괴가 지배적이고 심재 두께가 48mm와 61mm와 같이 두꺼운 경우는 면재-심재 분리가 지배적으로 관찰되었다.

• 한국안전학회지
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• 제21권1호
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• pp.92-95
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• 2006

This study is to find out how column with hole is behaved, compared to the normal one without hole. There might be existing buildings to make holes in the reinforced concrete column. Columns are made with commercially used compressive strength $240kg/cm^{2}$, air amount 5.0%, using re-bar of diameter D13 and D10 having yielding stress $4,000kg/cm^{2}$. The specimen were cured with temperature of $21{\pm}3^{\circ}C$. All specimens of five variables and all holes are geometrically considered and configurated. D3, D5 mean diameter 3cm and 5cm respectively. H1, H2 are the number of holes. Compressive pressure was forced in accordance with KS, following $0.6{\pm}0.4N/mm^{2}$ speed. Main re-bar's were strained with almost same shape through all the specimens. Hole diameter 5cm-having specimen showed cracking around hole. strains of back and front gauges of the specimen were showed similarly. Specimen having two holes in left and right from longitudinally axis resisted 7% less than the one having hole centrically from longitudinal axis. One hole having specimen with diameter 5cm resisted only 3% less than in case of 3cm diameter hole. Hole having in left and right from longitudinal axis will be less resistant than the case longitudinally arranged. Diameter 3cm hole showed less 10% capacity than normal one without hole. Capacity loss difference between diameter 3cm and 5cm showed almost none in case that they are arranged longitudinally.

• 화약ㆍ발파
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• 제32권2호
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• pp.9-15
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• 2014

콘크리트 기둥 발파 시 장약공 상태에 따른 지반 진동의 전파 특성을 확인하기 위해 몇 가지 기둥 구조물을 제작하였고, 각 기둥 구조물에 설치된 장약공의 상태를 달리하여 TNT로 발파하며 진동을 측정하였다. 회귀분석 결과, 사각 장약공이 원형 장약공보다 진동의 크기가 작고 감쇠가 더 빨랐으며 관통된 장약공보다 폐쇄된 장약공에서 진동의 크기는 크고 감쇠는 비슷하였다.

• 한국안전학회지
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• 제21권2호
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• pp.70-79
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• 2006

many plumbing system are needed in the ceiling of the building as it becomes advanced more and more. This leads to make effective space between ceiling level and slab less. Also, piping system is not suitably arranged and operated if it is bent around the columns which they are a lot. But this system can be more effective if it passes through the columns directly. Most people think that those columns should not be damaged with such as holes. But actually this is existed in a hotel building in switzerland. This study is to fing out how much capacity the columns become damaged and low using model size of $20cm{\times}30cm$ rectangular section, and 160cm long, in the structural test. it's compressive strength is focused on $240kg/cm^{2}$ design strength, commonly used in korea. Compressive test for them was done at Hanyang University using UTM one thousand tone(1000t) capacity. Variable numbers for the study are one hole of dia 3cm with distance 20cm or 40cm, two holes of dia 3cm with 20cm and 40cm distance, one hole of dia 5cm with distance 20cm and 40cm, two holes of dia 5cm with 20cm and 40cm distance, me eccentric hole with 20cm and 40cm distance, Normal(without hole). two test specimens of each variable are made for the test. ED5H20 capacity was 16.7% decreased, compared to normal one. While ED5H40 distant 40cm from the end of column top showed 19.5% capacity decrease, compared to normal one. Strain of ED5H20 diameter 5cm, in distance of 20cm form the top of the column was less 5% than the one of diameter 3cm. Finally, conclusions are that in case of hole diameter 3cm, located at 20cm from the end of the column top, capacity was decreased down to 3, percent only compared to the same diameter hole with 20cm distant from the end of it.

• 자동차안전학회지
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• 제5권2호
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• pp.57-61
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• 2013

A column for streetlamp has been damaged by severe wind loads such as typhoon. The stress concentration around the inspection hole may cause the collapse of the column for streetlamp. In this paper, the effects due to the wind load of 60 m/s and the car crash to the column at the speed of 48 km/h were considered to examine the design stability analysis of the column for streetlamp. The maximum von Mises stress did not exceed the yield stress of the material. Considering the car crash, the column for streetlamp was not collapsed.

• 한국안전학회지
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• 제16권3호
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• pp.89-98
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• 2001

There have been a lot of studies about repair & strengthening of the concrete structure. But there has almost not been my study on section damage effect due to holes drilled out for installing additional facilities or equipment, such as rack on the wall of building or underground culvert system, plumbing system through the column or wall of it, after being occupied. This study is to find out how much the section loss due to holes will give loss of section strength. We cm determine if we repair or reinforce it completely or not, using strength loss from the hole. Hole size of diameter 3cm, 2cm, lcm, depth of 3cm, 5cm, 10cm, and position of each hole has been considered as variables of this study. It is concluded that section loss 30% results in 53% of strength damage.

• Journal of the Korean Wood Science and Technology
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• 제31권2호
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• pp.69-76
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• 2003

곤충에 의한 침해는 건물의 앞쪽기둥에서 피해정도가 가장 크게 나타났다. 또한 기둥의 밑 부분과 중간부분, 그리고 윗부분 등 높이별로 구멍의 지름이 많은 차이가 있어, 각 부위별 가해 곤충의 종류가 틀린 것으로 판단되었다. 기둥의 높이별로는 기둥의 중간 정도의 높이에서 가장 피해가 큰 것으로 관찰되었다. 목재를 가해한 곤충의 크기를 짐작할 수 있는 구멍의 직경은 1 mm에서 10 mm까지 다양하였으며 대략 직경 5 mm 정도가 가장 많이 나타났다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.749-752
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• 2004

In a liquid-fueled ramjet engine, the insufficient mixing and evaporation result in the low combustion efficiency and combustion instability. Improving its spray characteristics and devising a means of mixing fuel droplets with air may compensate these disadvantages of liquid fuel ramjet engine. The jet penetrations of various fuel injectors were measured to investigate the spray characteristics of a liquid-fueled ramjet engine under high pressure air-stream conditions. The penetrations in high pressure conditions are smaller than the values calculated from Inamura's or Lee's equations, and, in the high pressure conditions, the jet penetrations are similar each other. In the dual hole injectors, the jet penetrations of rear orifice is rapidly increased due to the reduction of the drag, which is created by the jet column of front orifice. The jet penetration of rear orifice is increased because of the drag reduction created by the jet column of the front orifice. And, because of the drag reduction formed by the column of jet, the jet penetration in the rear orifice of dual hole injector is much larger than the jet penetration of single hole injector. As the distances of the orifice are increased, the jet penetrations of the rear orifice decrease.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1059-1064
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• 2001

This study is about accurate steel column position method in the Top down method's delicate part. When the concrete is placing, it is required that complementary measures to the transformation due to concrete pressure, column buckling, the trouble due to bar net inserting and so on. To solve the problem of exist method, the concrete is placed at the bottom of excavated hole in advance. then, the steel column is inserted into the excavated hole. With a new method try, the problem due to placing pressure and others is could be prevented. In this study, the concrete is examined with test-slump, slump flow, and compressive strength to do quantitative analysis of concrete. The factors of the experiment is plasticizer, retarder addition rate, fly ash substitution rate to cement. Considering of the new method try, the retarder added concrete properties-fluidity, viscosity, strength-is investigated as time lapsing.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.300-307
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• 2006

Integral pile shaft-column foundations are increasingly popular thanks to not only the comparative advantage of economy in constructing large cast-in-drilled-hole(CIDH) piles compared with driven piles with pile cap footings but also being free from problems associated with the critical column-footing connection. In this paper, the structural characteristics of integral pile shaft-column foundations as well as seismic analysis methodology and reinforcement details for seismic design are introduced.