• 한국가구학회지
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• 제21권6호
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• pp.469-478
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• 2010

본 연구에서는 두 개의 주요 구조부분으로 구성된 새로운 하이브리드 목조 벽체의 내화성능을 평가하였다. 수직하중을 전적으로 담당하는 기둥-보 형태의 기본 골조에 두 가지 형태의 벽체가 채워졌을 때 이 전체를 내력 벽체로 가정하고 그 내화성능을 평가하고자 하였다. 하이브리드 벽체의 기본 개념은 뼈대를 갖는 전형적인 가구의 구조로부터 채용되었다. 기본이 되는 기둥-보 골조는 국산 낙엽송 소재로서, 기둥은 $180mm{\times}180mm$, 보는 $180mm{\times}240mm$ 단면의 부재가 사용되었다. 기둥-보 골조의 내부에 채워지는 벽체는 두 종류로서, 하나는 블러킹이 사용된 일반적인 경골목구조 벽체이고, 또 하나는 구조용 패널 사이에 스티로폼 단열재가 채워져 일체화된 구조를 이루는 구조용 단열 패널 벽체이다. 내화성능 시험에 사용된 모든 벽체는 2겹의 방화석고보드를 화염 노출면에 부착하였다. 모든 벽체는 우선 기둥-보 골조가 없는 상태에서 표준화염 조건에서 내화성능 시험을 수행하였고 다시 기둥-보 골조와 결합된 형태로 내화성능 시험을 수행하였다. 시험에 적용된 화염조건은 KS F 2257의 조건을 적용하였고 시험 중 구조체 내부 각 부위의 온도변화도 측정하였다. 본 연구를 통해 기둥-보 골조의 보강이 목구조 벽체의 내화성능 향상에 상당히 기여하는 것으로 확인되었다.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.217-231
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• 2003

상보적인 특성을 갖는 골레이 수열을 이용하여 코드화된 신호를 송신하는 것은 SNR과 침투도를 향상시킬 수 있는 효과적인 방법이다. 그러나 각 주사선을 형성하기 위해 두 개의 상보적인 이진 코드를 연속하여 두 번 송신하기 때문에 프레임 율이 반으로 감소하게 된다 특히 이 방법은 측방향 해상도를 향상시키기 위해 다중 집속 기법(multi-zone focusing method)을 적용하면 송신 집속점의 개수에 따라 송신 횟수가 늘어나므로 프레임 율(frame rate)이 크게 저하된다. 본 논문에서는 이러한 문제를 해결하기 위해 변형된 직교 골레이 코드를 이용한 동시 다중 송신 집속 기법을 제안하였다 제안한 방법은 프레임 율의 저하 없이도 두 쌍의 직교 골레이 코드를 사용하여 서로 다른 위치에 동시에 송신 집속할 수 있다. 그리고 수신시에 정합 과정을 통해 분리, 압축한 다음 일반적인 다중 집속 기법과 같이 집속된 빔들을 결합함으로써 기존의 골레이 코드를 사용하는 송신 고정 집속 기법과 같은 프레임 율을 유지하면서도 측방향 해상도를 개선할 수 있다. 실제 초음파 영상을 위해 송신 신호로 사용되는 골레이 코드는 전송 전력 효율(Transmit Power Efficiency)을 높일 수 있도록 변형되었다. 컴퓨터 모사 실험과 실제 실험 결과는 제안한 방법이 기존의 방법에 비해 매우 향상된 측방향 해상도와 침투도를 갖는 초음파 영상을 제공한다는 것을 보여준다.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1931-1936
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• 2004

In this paper, modeling methods for the structural dynamic analysis employing single reference frame are presented and their modal and transient analysis results are compared. The geometric stiffening effects often occur when structures undergo large overall motion. These effects were considered in several structural previous modeling methods but the role of reference frame has never been scrutinized. In this study, modeling methods employing single reference frame are presented, and their numerical results are compared. The results show that discrepancy between the two modeling methods increases as the eccentricity of the structural system and the magnitude of the large overall motion increase.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
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• pp.54-57
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• 2000

In this paper, we propose a new interpolation method by using the motion between two moving image frames. In the proposed method, the movement is detected by using neighborhood pixels of target pixel in the past frame and the present frame. Then, H-shaped pseudomedian filter (below HPMED) is used for the still part of the image and Delta-shaped interpolation filter (below $\Delta$-shaped) for used in the moving part of the image. We detect the movement by comparing the differences between pixels in 4${\times}$5 window of the past frame and the present frame; the difference has a critical value. We simultaneously accomplish checking PSNR(peak signal noise ratio) and subjective assessment that is placed the focus on edge characteristic for assessment of result in computer simulation. The results show that the proposed adaptive method is better than the conventional methods.

• 한국안전학회지
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• 제13권2호
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• pp.13-21
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• 1998

This is a study on the natural vibration characteristics of Vehicle frame. Nowadays, many trucks freight the over-load, do the car designers consider the over-load about 200% in the design. It's necessary to make the model of a vehicle and simulate it for the test of driving condition, durability and vibration behavior before the vehicle is manufactured. If it is possible to make a simulation using the static and dynamic analysis, this is very useful in accomplishing an optimal design of the vehicle. In this paper, we studied the vibration characteristics of a truck body frame. The automobile body frame model for experiment is made smaller than real size frame with the ratio of 1/10. The vibration characteristics of a frame is considered as one of main factors in analyzing and improving the problem for ride comfort, noise and vibration reduction. Therefore, we experimented two method to neglect the nonlinearity. First is bolting and second is welding at the joint section. We compared computer simulation results and experimental data.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.183-191
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• 2018

In this paper, harmonic responses of infilled multi-storey frames are obtained by using a single variable shear deformation theory (SVSDT) and dynamic stiffness formulations. Two different planar frame models are used which are fully infilled and soft storey. The infill walls are modeled by using equivalent diagonal strut approach. Firstly, free vibration analyses of bare frame and infilled frames are performed. The calculated natural frequencies are tabulated with finite element solution results. Then, harmonic response curves (HRCs) of frame models are plotted for different infill wall thickness values. All of the results are presented comparatively with Timoshenko beam theory results to reveal the effectiveness of SVSDT which considers the parabolic shear stress distribution along the frame member cross-sections.

• Structural Monitoring and Maintenance
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• 제5권2호
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• pp.189-204
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• 2018

This paper examines the seismic responses of a reinforced concrete (RC) frame core-tube building with pre-pressed spring self-centering energy dissipation (PS-SCED) braces. The PS-SCED brace system consists of friction devices for energy dissipation, pre-pressed combination disc springs for self-centering and tube members as guiding elements. A constitutive model of self-centering flag-shaped hysteresis for PS-SCED brace is developed to better simulate the seismic responses of the RC frame core-tube building with PS-SCED braces, which is also verified by the tests of two braces under low cyclic reversed loading. Results indicate that the self-centering and energy dissipation capabilities are well predicted by the proposed constitutive model of the PS-SCED brace. The structure with PS-SCED braces presents similar peak story drift ratio, smaller peak acceleration, smaller base shear force and much smaller residual deformations as compared to the RC frame core-tube building with bucking-restrained braces (BRBs).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.467-469
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• 2006

In wireless network environments, as users' demands on high-speed data communications due to increase of multi-media services, the necessity of new high-speed WLAN technologies has appeared. Nowaday, IEEE is standardizing a new WLAN protocol caned as IEEE 802.11n. To effectively use wireless resources, IEEE 802.11n introduces MAC aggregation function which is similar to that in IEEE 802.11e. In case of transmitting several frames without MAC aggregation, the frames include individual frame header and trailer, and their corresponding acknowledgement frames can appear on wireless link. However, if they are aggregated into single MAC frame, we can reduce the number of used bits due to frame headers/trailers and also remove redundant acknowledgement frames. In this paper, we explain two different MAC frame aggregation methods for IEEE 802.11e and IEEE 802.11n and evaluate their throughput by simulations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.161-165
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• 2001

Bogie frame of the electric car is an important structural member for the support of vehicle loading. In general, more than 25 years' durability is necessary. Much study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. One of the useful methods is reliability-based approach. The objective of this paper is to estimate the structural integrity of the bogie frame of an electric car, which is under the running test. We used two approachs. In the first approach probabilistic distribution of S-N curve is used. In the second approach, limit state function is used.

• 소음진동
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• 제9권5호
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• pp.966-974
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• 1999

This paper introduces modeling and its modal analysis procedure for exact and closed form solution of in-plane vibrations of general Timoshenko frame structures using exact dynamic element method(EDEM). The derivation procedure of the exact system dynamic matrices for Timoshenko beam frames is described. A new modal analysis procedure is also proposed since the conventional modal analysis schemes are not adequate for the proposed, exact system dynamic matrix. The proposed method provides exact modal parameters as well as all kinds of closed form solutions for general frame structures. Two numerical examples are presented for validating and illustrating the proposed method. The numerical study proves that the proposed method is useful for dynamic analysis of frame structures.