• 대한방사선기술학회지:방사선기술과학
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• 제27권4호
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• pp.23-29
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• 2004

진단영역에서 사용하는 넓은 선속 X선 에너지에 대한 차폐물질의 투과 특성을 Archer의 수학적 모델을 적용하여 나타내었다. 인버터 방식의 고전압발생장치를 사용하는 X선 발생장치를 사용하여 관전압 60 kVp부터 140 kVp까지의 범위에서 납, 철, 콘크리트, 유리등의 차폐체의 투과 특성을 나타내었다. 이러한 인버터 방식의 고전압발생장치를 사용하는 진단영방사선발생장치의 관전압별 투과도는 진단방사선발생장치를 사용하는 작업공간에서의 차폐 설계 시 차폐물질의 종류와 두께의 설정에 도움이 될 것이다.

• 동력기계공학회지
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• 제10권4호
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• pp.78-82
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• 2006

Recently, The demands for the reduction of noise generated by transformers have been increasing. Almost all of the noise generated by transformers is a result of magnetostricitive vibration in the core. The noise radiates into the atmosphere from the tank through the insulation oil. As the noise of transformer irritates residents, needs for decreasing the noise of transformer have been arised. One method of reduction such a noise is to build a free-standing enclosure of concrete and steel plates around the transformer. However, this method has some disadvantages. Another method of noise reduction is to mount a close-fitting sound insulation panel on the side of a transformer tank. Side plate vibrations of transformer are transmitted to such a sound insulation panel along two paths. In one case, they are transmitted through air by sound pressure and in the other through supporting structures. In the paper, the vibration and noise effect which is transferred from reinforce channel to insulation panel generated by transformer have been identified for the several kinds of insulation panel and damping sheet analytically and experimetally.

• Structural Engineering and Mechanics
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• 제86권3호
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• pp.349-359
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• 2023

This paper presents a technique for determining the optimal number of elements in stochastic finite element analysis based on reliability analysis. Using the change-of-variable perturbation stochastic finite element approach, the probability density function of the dynamic responses of stochastic structures is explicitly determined. This method combines the perturbation stochastic finite element method with the change-of-variable technique into a united model. To further examine the relationships between the random fields, discretization of the random field parameters, such as the variance function and the scale of fluctuation, is also performed. Accordingly, the reliability index is calculated based on the explicit probability density function of responses with Gaussian or non-Gaussian random fields in any number of elements corresponding to the random field discretization. The numerical examples illustrate the effectiveness of the proposed method for a one-dimensional cantilever reinforced concrete column and a two-dimensional steel plate shear wall. The benefit of this method is that the probability density function of responses can be obtained explicitly without the use simulation techniques. Any type of random variable with any statistical distribution can be incorporated into the calculations, regardless of the restrictions imposed by the type of statistical distribution of random variables. Consequently, this method can be utilized as a suitable guideline for the efficient implementation of stochastic finite element analysis of structures, regardless of the statistical distribution of random variables.

• 한국강구조학회 논문집
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• 제22권1호
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• pp.21-31
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• 2010

본 연구에서는 구조 케이블의 인장력 모니터링을 위한 무선 임피던스 센서노드를 개발하였다. 이를 위해 다음과 같은 연구가 수행되었다. 첫째, 경제적이고 자동화된 구조 케이블의 인장력 모니터링을 위한 무선임피던스 센서노드를 설계/제작 하였다. 둘째, 자동화된 인장력 모니터링을 위해 임피던스 기반 모니터링 기법을 무선 센서노드에 내장하였다. 셋째, 측정 범위가 제한적인 무선임피던스 센서노드의 한계점을 극복하기 위하여 인터페이스 와셔를 이용하는 구조케이블 인장력 모니터링 기법을 제안하였다. 마지막으로 내장형/외장형 텐던을 가지는 모형 프리스트레스트 콘크리트 거더에 대하여 무선임피던스 센서노드와 인터페이스 와셔를 이용하는 모니터링 기법의 적용성을 평가하였다.

• 기술사
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• 제15권4호
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• pp.12-24
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• 1982

East Parts of Bangladesh have been benifited by low cost energy generated by domestic natural gas but West parts where energy generated by imported fuel. Bangladesh Government authority has very much concerned to transmit the low cost electricity to the West from the East for past several years. To solve such concerns, cross-country 230kv double circuits Power transmission line was proposed, however there was a big obstacle for the realization of this line to cross the Jamuna river which has 12 km long width with a deep muddy river bed. A consultant engineering firm named Merz-Mclellan anyway finalized this plan and a world-wide bid was announced on June 31, 1979. Due to the expected difficulty to construct the towers on sea like area, only three construction groups have participated. including a Korean joint venture organization of Samsung-Korean Developement corporation-Kolon Electric Machinery company. After 3 months bid evaluation, contract was awarded to Korean Consosium and KEM Co was in charge of designing steel towers with anchor bolts and base plates beside to electrical engineering field. Then KEM Co have faced and over-comed many unenpected technical difficulties such as forced eccentricity joint on base plate, distorsion issue of 60mm thick plates welding, threading anchor bolts, tad heat treatment of some anchor bolts, disagreement from Consultant Engineer on multiplying factor of leg stresses for 45$^{\circ}$ wind and on reducing O.L.F for wind loads on cables for such 1220km long spans. After spending two years long period for designing and engineering towers, base plates, and anchor bolts, first shipment of tower was finally realized on Nov. 8, 1981 and on the other hand KDD has proceeded concrete caisson work on schedule at Jamuna river site and expected to complete tower erection and stringing of cables within this year of 1982 which was original completion target.

• 한국강구조학회 논문집
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• 제18권5호
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• pp.535-542
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• 2006

본 논문에서는 압연형강(H형강)을 이용한 강합성 교량에 대한 3차원 유한요소 해석을 실시하여, 가로보가 활하중 횡 분배에 미치는영향에 대해 검토하였다. 고려된 주요 변수는 주형과 가로보의 단면2차모멘트비, 가로보의 설치 여부, 가로보의 개수 등이다. 유한요소 해석을 통한 활하중 횡분배 계수와 함께 관용적인 격자해석에 의한 활하중 횡분배 계수도 비교하였다. 분석결과에서 가로보는 활 하중 횡분배에 별다른 영향을 미치지 못하며, 콘크리트 바닥판이 활하중 횡분배에는 가장 중요한 역할을 하는 것으로 나타났다. 따라서 활하중 횡분배를 목적으로 설치하는 가로보는 제거가 가능한 것으로 판단된다.

• 한국강구조학회 논문집
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• 제19권3호
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• pp.271-280
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• 2007

본 연구에서는 단재하경로 구조로 인식되는 2-거더교에서 한 개 거더의 손상 시 여유도를 평가하기 위한 실험적 연구를 수행하였다. 실험변수는 하부 수평브레이싱으로 하여 하부 수평브레이싱이 설치된 경우와 설치되지 않은 경우의 단경간 1/5 모형 시험체 2개를 제작하였다. 먼저 균열이 없는 정상상태 시험체에 대해서 탄성범위 내에서 재하실험을 수행하였으며, 이후 지간 중앙부의 한 개 거더에 인위적인 손상을 가한 후 종국상태에 이르기까지 재하 실험을 수행하였다. 실험으로부터 정상상태의 교량에서도 수평브레이싱은 하중 재분배 역할을 수행하였으며, 한 개 거더에 심각한 손상이 발생한 경우에는 가로보와 바닥판이 비균열 거더 측으로 하중 재분배 기능을 일부 수행하였으나, 특히 하부 수평브레이싱은 2-거더교의 손상 시 여유도 향상에 매우 중요한 기능을 하는 것으로 나타났다.

• 한국농촌건축학회논문집
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• 제15권3호
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• pp.17-24
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• 2013

This study examined and investigated architectural characteristics such as the use of buildings, the number of layers, and structure, and roof landscape characteristics such as roof types, materials, and color in rural villages which were located on the street on the assumption that the landscape of rural villages should be managed by considering visual aspects. The results were as follows. The commonest frequency was found in 'residence'(2/3) for the use of buildings and 'masonry structure'(2/3) for the structure. 'Wood structure' and 'light gauge steel structure(prefabricated structure)' were also commonly found. The results suggest that although many rural houses have partially improved by agricultural and fishery development projects and garden suburbs has been increased by city residents' desire for rural life, there have been still many old houses. Frequently used roof types were a gambrel roof and a hipped roof. Roof materials were mixed in several materials such as tiles, slate, panels, color steel plate, reinforced concrete, and asphalt shingles. Roof color was also mixed in several colors such as reddish N7 and N0.5 of Neutral color, 10R3/6 and 10R3/10 of R color, 7.5B4/10 and 7.5B7/8 of B color and 5G8/6 of G color. The result suggests that roof color impedes the landscape of rural villages on the street. Based on the results, some roofs of rural villages were improved by the support of the government or the local governments but there are still many old roofs. The mixture of improved roofs and old roofs mainly contributed to impeding the landscape of rural villages and it was probably caused by the lack of systematic landscape plans by individual improvement of buildings. Therefore, it is necessary to devise systematic landscape plans in consideration of local identity and neighboring environment. In particular, the guideline for roof color influencing a street landscape should be established.

• Smart Structures and Systems
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• 제15권1호
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• pp.99-117
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• 2015

The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.

• 한국건축시공학회지
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• 제23권6호
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• pp.715-726
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• 2023

본 연구에서는 수소 충전소와 같은 폭발 가능성을 가진 구조물들의 안전 설계 방안으로 방호패널이 희생 부재로 설치되어 구조물의 직접적인 피해를 최소화하고 회복 탄력성을 가질 수 있어야 한다고 제시하였다. 이를 위해 비상체의 고속 충돌 상황에서 방호 패널이 구조물과 밀착 또는 이격 설치되었을 때 구조물이 받는 영향을 정량적으로 평가하는데 실험의 초점을 맞추고 있다. 실험 설계는 우수한 재현성을 위해 기존에 주로 사용한 콘크리트 구조부재 대신 강판을 사용하며, 철판 배면의 변형 차이를 통해 구조부재의 충격을 비교·분석하였다. 또한, 방호 부재의 이격재로 사용한 탄성체의 물성 변화와 방호부재 및 탄성체에 따른 충격파 전달 시간의 차이가 구조부재에 미치는 영향을 조사하였다.