• 한국강구조학회 논문집
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• 제9권4호통권33호
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• pp.673-682
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• 1997

이 논문에서는 회전관성과 전단변형이 변화곡률 아치의 고유진동수에 미치는 영향을 분석하였다. 임의의 변화곡률을 갖는 등단면 아치의 자유진동을 지배하는 미분방정식을 유도하였으며, 유도된 미분방정식에 회전-회전, 회전-고정 및 고정-고정의 단부조건을 갖는 포물선, 원호 및 타원 아치를 적용하여 수치해석하였다. 해석결과로서 무차원 변수인 아치높이 지간길이비 및 세장비 변화에 따론 최저차 4개의 무차원 고유진동수를 산출하였다.

• 한국공간구조학회논문집
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• 제4권2호
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• pp.63-71
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• 2004

트러스형 공간 구조물은 무주의 대공간을 덮을 수 있는 장점과 구조적 성질이 동일한 등가 연속체 쉘 로 치환하여도 비교적 정확한 해를 얻을 수 있다는 장점으로 인해 21세기 첨단 구조물의 한 장인 초대형 구조물 분야에 많이 활용되고 있으며, 효율적인 부재의 이용과 대량생산의 가능성으로 인해 많은 발전을 해 왔다. 그러나 이러한 쉘 형태의 공간 구조물은 구조 거동의 특성상 주로 구조안정문제가 구조설계에서 해결해야하는 핵심적인 기술력이 되며, 이를 어떻게 해결하여야 할 것인가의 문제는 아직도 많은 연구자들에게 난제로 남아 있다. 즉, 연속체 쉘 구조의 원리에서 긴 경간을 얇게 만들면, 뜀좌굴과 분기좌굴같은 불안정 거동이 나타나게 되며, 이러한 쉘형 구조 시스템에서 구조 불안정 문제의 특징은 초기 조건에 매우 민감하게 반응한다는 것이고, 이런 문제들은 수학적으로 비선형 문제에 귀착하게 된다. 따라서, 본 논문에서는 공간 프레임형 구조물의 불안정 현상을 살펴보기 위하여, 다양한 파라메타중 초기불완전량과 rise-span 비가 트러스 구조물의 불안정 현상에 미치는 영향을 알아보고자 하며, 이를 위해 1-자유절점 공간구조물, 2-자유절점 공간구조물, 다-자유절점 공간구조물을 예제로 채택하여 불안정 거동을 살펴보고자 한다.

• 한국공간구조학회논문집
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• 제12권1호
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• pp.59-68
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• 2012

대공간 구조시스템의 하나인 스페이스 프레임 구조는 종횡의 부재가 3차원적으로 연결되어 입체적으로 외부 힘에 저항하는 구조로써 높은 강성을 갖는다. 또한 균등한 응력 분담이 가능하도록 설계되는 스페이스 프레임 고유의 역학적 특성에 기인하여 경량화가 가능하다. 스페이스 프레임의 구조안정 문제는 구조물의 여러 가지 조건에 따라 결정되며 매우 중요하다. 본 연구에서는 기하학적 형태에 따른 래티스 돔의 동적구조불안정 특성을 알아보기 위해 2-자유 절점 구조물을 통해 스페이스 프레임의 붕괴 메터니즘을 파악하고, 기하학적 형태에 따라 Star Dome, Parallel Lamella Dome, 3-Way Grid Dome을 모델로 선택하여 동일레벨의 주기성이 없는 STEP 하중에 의한 동적외력 하에서의 라이즈-스팬(${\mu}$)비 및 형상불완전에 따른 불안정 거동 특성을 알아본다.

• Earthquakes and Structures
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• 제15권5호
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• pp.453-462
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• 2018

Damages to buildings affected by a near-fault strong ground motion are largely attributed to the vertical component of the earthquake resulting in column failures, which could lead to disproportionate building catastrophic collapse in a progressive fashion. Recently, considerable interests are awakening to study effects of earthquake vertical components on structural responses. In this study, detailed modeling and time-history analyses of a 12-story code-conforming reinforced concrete moment frame building carrying the gravity loads, and exposed to once only the horizontal component of, and second time simultaneously the horizontal and vertical components of an ensemble of far-field and near-field earthquakes are conducted. Structural responses inclusive of tension, compression and its fluctuations in columns, the ratio of shear demand to capacity in columns and peak mid-span moment demand in beams are compared with and without the presence of the vertical component of earthquake records. The influences of the existence of earthquake vertical component in both exterior and interior spans are separately studied. Thereafter, the correlation between the increase of demands induced by the vertical component of the earthquake and the ratio of a set of earthquake record characteristic parameters is investigated. It is shown that uplift initiation and the magnitude of tensile forces developed in corner columns are relatively more critical. Presence of vertical component of earthquake leads to a drop in minimum compressive force and initiation of tension in columns. The magnitude of this reduction in the most critical case is recorded on average 84% under near-fault ground motions. Besides, the presence of earthquake vertical components increases the shear capacity required in columns, which is at most 31%. In the best case, a direct correlation of 95% between the increase of the maximum compressive force and the ratio of vertical to horizontal 'effective peak acceleration (EPA)' is observed.

• 전자공학회논문지 IE
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• 제47권2호
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• pp.32-37
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• 2010

본 연구에서는 초소형화의 욕구와 우수한 신뢰성을 가진 일체형 SMD 인덕터 코어를 개발하기 위하여 전력값에 따른 온도 특성을 분석하였다. 전자부품의 온도가 상승하면 소자의 정상적인 동작을 보장하기 힘든 기능적 장애를 가져오고, 부품의 고장율을 높여 수명을 단축하게 된다. 또한, 열응력이나 열팽창에 의하여 부품에 충격을 주고 오동작을 일으키게 되어 신뢰성에 많은 영향을 미치게 된다. 일체형 SMD Inductor Core를 주위온도와 소자온도 차에 의한 온도상승을 측정하였으며, 각 전력값에 따른 온도 특성을 통해서 안정된 전력값을 얻을 수 있었고, 측정된 직류 전류와 저항 $R_dc$를 이용하여 시뮬레이션한 결과 40[$^{\circ}C$]의 온도 상승분에서 양호한 정격 전류값을 찾을 수 있었다.

• 한국건축시공학회지
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• 제2권2호
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• pp.121-127
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• 2002

The functions and uses of existing buildings are not properly changing as modern life needs. As a result, the frequent reconstruction(construction after removal) of existing buildings have been done but it became more and more difficult because of strengthening of regulations and systems concerning construction. And also it has several disadvantages like lower plot ratio and site coverage than existed buildings, enormous construction cost, production of waste-construction materials and thoughtless consumption of natural resources, which gives rise to environmental pollution. Therefore renovation is brought to the fore. In Korea, many business buildings were constructed in 1960s-1970s, during the period of high growth. Such buildings needs to be repaired in whole. It is caused by the change of social, economic, and cultural conditions and deterioration of equipments. Therefore renovation meets some necessary conditions; recovery of building functions and extension of building life span. In case study, the present state of renovation in business buildings is 1) Basic safety, for example, fire prevention and crime prevention, is great important. 2) Advanced technology, INS(international news service), IBS(Intelligent Building System), and internationalization, is pursued for adapting to multimedia ages. 3) It tries to promote proficiency, and to save the energy using spatial environment and natural energy(light and sound). Also, improving comfortable level of users and installing equipments for physically handicapped person needs to be considered.

• 한국농공학회지
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• 제43권3호
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• pp.85-93
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• 2001

In this study, a computer program considering shape imperfections of arch under dynamic loading was developed. The shape imperfection of arch was assumed as higher degree polynomial expressed as $\omega$$_{i}$ = $\omega$$_{o}$ (1-(2$\chi$/L)$^{m}$ )$^n$and sinusoidal curve such as $\omega$$_{i}$ = $\omega$$_{o}$ sin(η$\pi$$\chi$/L). In finite element formulation, the material nonlinear behavior was assumed the elasto-viscoplastic model highly corresponding to the real behavior of the material and the geometrically nonlinear behavior was modeled using Lagrangian description of motion. Also, the behavior of steel was modeled by applying yield criteria of Von Mises. The developed program was applied to the analysis of the dynamic behavior for the clamped beam subjected to the concentrated load at midspan and the results were compared with those from other research to investigate accuracy of the presented finite element program. In numerical examples, the shape imperfections of L/500, L/1,000 and L/2,000 were considered and the modes of shape imperfections of the symmetric and antisymmetric were adopted. The effects of the shape imperfections on the dynamic behavior of arch were conspicuous and results of analysis indicate that the reasonable values of arch rise to arch span ratio ranged between 0.1 and 0.3.

• 한국공간구조학회논문집
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• 제3권1호
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• pp.87-97
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• 2003

The structural system that discreterized from continuous shells is frequently used to make a large space structures. As well these structures show the unstable phenomena when a load level over the limit load, and snap-through and bifurcation are most well known of it. For the collapse mechanism, rise-span ratio, element stiffness and load mode are main factor, which it give an effect to unstable behavior. In our real situation, most structures have semi-rigid joint that has middle characteristic between pin and rigid joint. So the knowledge of semi-rigid joint is very important problem of stable large space structure. And the instability phenemena of framed space structures show a strong non-linearity and very sensitive behavior according to the joint rigidity For this reason In this study, we are investigating to unstable problem of framed structure with semi-rigidity and to grasp the nonlinear instability behavior that make the fundamental collapse mechanism of the large space frame structures with semi-rigid joint, by proposed the numerical analysis method. Using the incremental stiffness matrix in chapter 2, we study instability of space structures.

• 한국공간구조학회논문집
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• 제18권2호
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• pp.59-67
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• 2018

Various pilotis are installed in the lower part of high rise buildings. Strong winds can generate sudden airflow around the pilotis, which can cause unexpected internal airflow changes and may cause damage to the exterior of the piloti ceiling. The present study investigates the characteristics of peak wind pressure coefficient for the design of piloti ceiling exteriors by conducting wind pressure tests on high rise buildings equipped with penetration-type and end-type pilotis in urban and suburban areas. The minimum peak wind pressure coefficient for penetration-type piloti ceilings ranges from -2.0 to -3.3. Minimum peak wind pressure coefficient in urban areas was 30% larger than in suburban areas. In end-type piloti ceilings, maximum peak wind-pressure coefficient ranges from 0.5 to 1.9, and minimum peak wind-pressure coefficient ranges from -1.3 to -3.6. With changes in building height, peak wind pressure coefficient decreases as the aspect ratio increases. Peak wind-pressure coefficient increases with taller pilotis. On the other hand, when piloti height decreases, the absolute value of the minimum peak wind pressure coefficient increases.

• 한국공간구조학회논문집
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• 제20권4호
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• pp.63-71
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• 2020

The fluctuating wind pressure of the low rise ratio(f/D=0.1) for the elliptical dome roof was analyzed to compare it with the previous studies of circular dome roofs. Wind tunnel test were conducted on a total of 10 wind directions from 0° to 90° while changing wall height-span ratios(H/D=0.1-0.5). For this, meanCP, rmsCP and wind pressure spectrum were analyzed. The analysis result leads to find differences in the shape of the spectra in the spanwise direction and leeward of the elliptical dome according to the wind direction variations of the elliptical dome roof.