• Wind and Structures
• /
• 제10권2호
• /
• pp.135-151
• /
• 2007

This paper examines the extreme gust profiles obtained by conditionally sampling full-scale velocity data obtained in the lower part of the atmospheric boundary layer. It is demonstrated that three different types of behaviour can be observed in the streamwise component of velocity. In all cases the corresponding vertical velocity component illustrates similar behaviour. An idealised horseshoe vortex model and a downburst model are investigated to examine if such structures can explain the behaviour observed. In addition, an empirical model is developed for an isolated gust corresponding to each of the three types of behaviour observed. It is possible that the division of the gust profile into three different types may lead to an improvement in the correlation of extreme gust events with respect to type.

• 한국항만학회지
• /
• 제10권1호
• /
• pp.25-36
• /
• 1996

Generally, it is pointed out that a nonlinear analysis is needed to estimate accurately the water surface fluctuation and dynamic responses of a floating structure in case of large wave reflection. In this study, a frequency-domain method is applied and newly developed to analyze the nonlinear characteristics of the air-chamber floating breakwater. The air-chamber floating breakwater in this study can control well the wave transformation, motions of the structure and its natural frequency by adjusting the air depth in the chamber. Experiments are carried out to verify the numerical results. It is appeared that the mean water level is setup in the anti-node and setdown in the node, while the nonlinearity in wave profile is larger in the node than in the anti-node. Because of vertical mooring system, the sway, especially the time-independent nonlinear component, plays predominant role in the motion. On the other hand, the time-dependent component, as well as the time-independent one to the tensile force of mooring line contributes greatly, and the time averaged value presents tensional force oriented to the onshore side due drift force.

• 디지털콘텐츠학회 논문지
• /
• 제8권3호
• /
• pp.329-339
• /
• 2007

본 논문은 연속적으로 입력되는 동영상에서 시공간 정보를 이용하여 다양한 조명환경에서도 실시간 적용이 가능한 얼굴영역 검출기법을 제안한다. 제안한 알고리즘은 연속된 두개의 연속 영상에서 에지 차영상을 구하고 연속적으로 입력되는 영상과의 차분 누적영상을 통해 초기 얼굴영역을 검출한다. 초기 얼굴영역으로부터 외부 조명의 영향을 없애기 위해, 검출된 초기 얼굴영역의 수평 프로파일을 이용하여 수직 방향으로 객체영역을 이분하며, 각각의 객체영역에 관해 주색상 밝기를 구한다. 배경과 잡음 성분을 제거한 후, 분할된 얼굴영역을 통합한 주색상 밝기 분포를 이용하여 타원으로 근사화 함으로써 정확한 얼굴의 기울기와 영역을 실시간으로 계산한다. 제안된 방법은 다양한 조명조건에서 얻어진 동영상을 이용하여 실험되었으며 얼굴의 좌 우 기울기가 $30^{\circ}$이하에서 우수한 얼굴영역 검출 성능을 보였다.

• 한국응용과학기술학회지
• /
• 제17권4호
• /
• pp.240-247
• /
• 2000

Two-component polyurethane flame-retardant coatings were prepared by blending trichloro aromatic modified polyesters(TCMPs) and polyisocyanate. TCMPs were synthesized by polycondensation of trichlorobenzoic acid(TCBA), a flame-retardant component, with adipic acid, 1,4-butanediol, and trimethylolpropane. The content of TCBA was varied in 10, 20, and 30 wt% for the reaction. These new flame-retardant coatings showed various properties comparable to other non-flame-retardant coatings. Moreover, we carried out the combustion test and the flammability test for our flame-retardant coatings. The results of vertical burning test for the coatings containing more than 20 wt% of TCBA were determined as 'no burn'. The results of flammability test for the coatings with 20 wt% and 30 wt% of TCBA contents indicated the limiting oxygen index(LOI) values of 25% and 28% respectively, which implied relatively good flame retardancy.

• 대한건축학회논문집:구조계
• /
• 제35권5호
• /
• pp.117-124
• /
• 2019

Nonstructural elements are installed according to the function of a building, and refer to the elements other than a structural system that resists external loads. Although the nonstructural elements had the largest part of seismic loss of buildings, seismic design of buildings mainly focuses on structural system and the seismic design of nonstructural elements are rarely conducted. In this study, the seismic design provisions of nonstructural elements presented in Uniform Building Code (UBC) and International Building Code (IBC) were investigated in order to analyze the seismic design considerations of nonstructural elements presented in Korean Building Code (KBC). The results showed that the equivalent static load applied to seismic design of nonstructural elements was revised to take into consideration a total of five items such as effective ground acceleration, vertical amplification factor, response amplification factor, response modification factor, importance factor.

• Korean Journal of Hydrosciences
• /
• 제6권
• /
• pp.99-105
• /
• 1995

External forecs acting on a pipe bend change when a transient pressure wave propagates through the bend. Analytical expressions are derived to compute the changes of these forces which depend mainly on static pressure rather than fluid momentum. This analysis reveals that the change of the vertical component of the force acting on a pipe bend with an angle larger than 90 may reverse in direction during the passage of a pressure wave through the bend.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.427-430
• /
• 1995

This paper proposes a new image processing algorithm to recognize korean documents. It take out the region of syllable area from input character image, then it makes recognition of a consonant and a vowel in the character. A precision segmentation is very important to recognize the input character. The input image has 8-bit gray scaled resolution. Not only the shape but also vertical and horizontal lines dispersion graph are used for segmentation. Theresult shows a higher accuracy of character segmentation.

• 대한수학회보
• /
• 제41권2호
• /
• pp.283-297
• /
• 2004

We have obtained a simplified model for the mush under the assumption of the temperature, the solid fraction and the vertical component of the velocity, depend on upward coordinate z only. We have found solutions in the asymptotical limit and solved numerically for the model.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2006년도 춘계학술대회 학술발표 논문집 제16권 제1호
• /
• pp.241-244
• /
• 2006

본 논문은 지구자계를 이용하여 3축 자계센서의 수직 성분자계를 보정하는 방법과 장치를 제안한다. 자계센서는 설치각도 및 이득오차에 의해 출력 특성이 변화한다. 따라서 자계센서를 사용하기에 앞서 보정이 필요하다. 지구에서 발생되는 지구자계를 이용하여 간편하게 센서의 설치각도 및 이득오차에 의한 영향을 보정하였으며 이를 위한 장치를 설계하였다. 제안한 방법은 실험을 통하여 실용성을 검증하였다.

• ETRI Journal
• /
• 제27권6호
• /
• pp.788-797
• /
• 2005

This paper describes the design and realization of an extra high frequency band $8{\times}8$ microstrip Butler matrix. Operation at 36 GHz is achieved with a frequency bandwidth exceeding 400 MHz. The circuit is implemented on a bi-layer microstrip structure using conventional manufacturing processes. This planar implementation of a Butler matrix is a key component of a switched beam smart antenna with printed antenna elements integrated on-board. Conception details, simulation results, and measurements are also given for the components (hybrid couplers, cross-couplers, and vertical inter-connections) used to implement the matrix.