• Journal of the Korea Concrete Institute
• /
• v.14 no.5
• /
• pp.718-725
• /
• 2002

A wall type friction damper is newly Proposed in this paper to improve the performance of R/C framed structures under earthquake loads. Although traditional dampers are usually placed as bracing members, the application ot bracing-type dampers into R/C structures is not as simple as those of steel structures due to the connection between R/C members and dampers and the stress concentration in connection region. Proposed damper is consisted of Teflon-sheet slider and R/C shear wall. The damper can also avoid stress concentration and reduce P-Δ effect. To evaluate the performance of proposed damper, nonlinear dynamic analyses are carried on 10 story and 3 bay R/C structures with numerical model for the damper. It is shown that the damper reduces the inter-story drifts and the time-historic responses; especially the damper prevents from forming plastic hinges on the lower columns.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.07a
• /
• pp.60-61
• /
• 2002

Laser-induced incandescence (LII) 측정법은 조사된 레이저에 의하여 입자가 가열됨에 따라서, 그 온도에 상응하는 흑체복사의 시간적 감소추이가 입자의 크기에 따라서 달리 나타나는 것을 이용하여 입자의 크기를 측정하는 방법이다. LII 감쇄법은 레이저에 의하여 가열된 입자의 에너지 균형 상관식에서 입자의 크기가 클수록 신호의 감쇄속도가 느리고, LII 신호의 감쇄비가 실험적으로 입자의 크기에 비례한다는 사실을 이용하여 연소진단에 응용되어 왔다. (중략)

• Journal of Astronomy and Space Sciences
• /
• v.12 no.1
• /
• pp.14-20
• /
• 1995

We calculated the wind velocities for 32 Cyg in order to understand how influence a damping length on the wind of supergiant driven by Alfven waves. Four cases, $\lambda$=0.9, 1.0, 5.0, the ratio of the damping length to the supergiant's radius, and the damping length increasing linearly with the distance from the star, were compared. The results showed the forces by Alfven waves gave the major contribution to the wind velocity but the forces by the pressure and gravitation did little. The model for the damping length with the linear relation showed the rapid increased due to short damping length near the surface of the star.

• Journal of Wetlands Research
• /
• v.23 no.2
• /
• pp.173-182
• /
• 2021

It is important to extract and assess low-flow recession characteristics for water resources management in the upper reaches of a stream. It is difficult to express the groundwater flow recession characteristics for streamflow synthetically. The linear recession model has been widely used by baseflow recession analysis for reason of simplicity and convenience, but recent studies show that nonlinear recession models fit well, and the relationship between the reservoir storage of shallow unconfined aquifers and the groundwater discharge was to be identified as nonlinear in the literature based on the analysis of numerous streamflow recession curves. The objective of the study is to decode these nonlinear characteristics, including evaporation loss, storage, and recharge of groundwater using streamflow. By analyzing the observed time series of streamflow from the study area, which is the Pyeongchang River basin in Korea, the main components of the underlying groundwater balance, namely, discharge, evaporation loss, storage, and recharge, can be identified and quantified. As a result of the study, depletion of groundwater by evapotranspiration losses through the water uptake of tree roots was found to bias the recession curves and the estimated reservoir parameters. The seasonality of both rainfall and potential evaporation, analysis of the recession curves, stratified according to time of the year, allowed the quantification of evapotranspiration loss as a function of a calendar month and stored groundwater storage.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.04a
• /
• pp.159-169
• /
• 2000

본논문에서는 강섬유 철근 콘크리트 보(SFRC) 의 감쇄 거동에 대해서 실험적인 방법과 수치 해석적인 방법으로 연구를 수행하였다 SFRC는 보다 향상된 에너지 소산능력으로 일반 철근 콘크리트보에 비하여 뛰어난 감쇄 거동을 보인다. 감쇄거동은 종방향 철근비강섬유의 형태와 부피 콘크리트 강도 응력 수준등에 의해 영향을 받는다 SFRC보의 감쇠는 다양한 수준의 균열상태에서의 동적실험 데이터를 통하여 평가하였다 곡률과 감쇠의 관계식에 기초한 유한요소 프로그램(TICAL) 이 개발되었으며 0.44%의 강섬유를 혼입한 보의 경우 5-35%의 감쇠비 증가를 보였다

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.9 no.1
• /
• pp.24-30
• /
• 1985

An experimental work to predict critical flow velocity to give whirling instability on staggered array tube banks model which is located in wind tunnel is presented. The critical flow velocity was obtained by measuring flow induced tube vibration on three tube array models having different pitch to diameter ratio as changing damping ratio and natural frequency of tube model. The obtained experimental results are directly compared with the numbers of other investigators and partly proved the truth of Blevin's new idea to predict critical flow velocity.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.1686-1690
• /
• 2010

우리나라 면적의 약 67%에 이르는 660만ha의 산림 중 침엽수림은 혼효림을 포함하여 약 74%를 차지해 활엽수림보다 넓게 분포하고 있다. 이와 같이 넓은 산림은 가뭄, 홍수와 같은 수문현상과 관련이 있으며 강우에 따른 유출에의 기여하는 바가 클 뿐만 아니라 강우, 증발산, 침투 유출에 이르는 다양한 수문현상이 복합적으로 나타난다. 특히, 최근 임목밀도의 증가가 오히려 증발산량의 증가, 옆면에 의한 강우 차단량의 증가 등을 발생시켜 가뭄과 홍수 또는 산사태의 원인이 될 수 있으며, 수자원 함양을 저해하는 요소로 작용하고 있다는 우려의 목소리가 나오고 있다. 따라서 산림지역의 증발산과 관련 있는 토양수분의 지속적인 모니터링과 감쇄특성 및 토양수분 환경에 대한 연구는 중요한 요소 연구가 될 수 있다. 봄에서 여름으로 진행되는 시기에는 강우발생에 비해 수목의 생육이 활발하여 증발산에 따른 토양수분 변화 및 감소가 급격하게 일어나며, 여름에는 토양수분의 감소도 뚜렷한 반면, 강우사상도 많이 발생하여 이에 따른 변화폭이 크게 나타난다. 또한, 가을에서 겨울로 진행되는 시기에는 수목의 생육의 둔화와 기온 하강으로 인하여 토양수분 감쇄현상 및 변화가 적게 나타나 토양수분의 변화양상이 계절마다 다르게 나타난다. 이에 토양수분의 감쇄현상을 파악하면 곧 산림지역에서의 증발산량 및 토양수분 소비특성을 파악할 수 있기 때문에, 산림에서 실제 토양수분 모니터링과 이를 통한 시간별, 깊이별 토양수분 변화 및 감쇄현상을 파악하는 것은 중요하다. 따라서 본 연구에서는 침엽수 산림에서의 토층별 월별 토양수분의 감쇄특성을 분석하기 위하여 침엽수림에서 토양수분 장기 모니터링 시스템을 구축하여 시간별, 토층별 토양수분 모니터링을 실시하고, 이를 바탕으로 침엽수림에서의 토양수분 감쇄현상을 분석하였다. 또한 토양수분 데이터 및 기상자료를 활용하여 월별, 기간별 토양수분 감쇄곡선을 산정하고 감쇄상수를 비교하였으며, 감쇄특성에 대하여 비교 분석하였다.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.3
• /
• pp.103-110
• /
• 2008

Strategically, the Patrol Killer Medium (PKM) ought to run at high speed that produces largely vibration by propeller, in a consequence, the vibration gradually deterioratescrews' working condition and increases the possibility of SONAR detection. In this paper, we propose the propeller damper, which is one of waysto reduce the vibration induced by the propeller, and simulate the ability of the damper numerically. The propeller damper was designed to apply to an isolated plate at the bottom flat board of ship which is directly affected by the fluctuating pressure. The dynamic pressure for the stern part of the PKM is calculated by using the DnV rule and the numerical analysis when the propeller damper applied or not, is performed with ANSYS at the isolated plate that simplified. From the analysis, the damping effect of the proposed propeller damper is confirmed and the reduction ratio for each compartment is estimated based on the experimental data in the PKM.

• Journal of the Korea Computer Graphics Society
• /
• v.15 no.1
• /
• pp.1-6
• /
• 2009

This paper presents a new CIP method for unstructured mesh to reduce the numerical dissipation. To reflect precise physical characteristics, CIP method updates both the physical quantity and the derivative information. The proposed method uses the Finite Volume Method(FVM) to solve the non-advection term of CIP equation. And we performed several experiments to improve the accuracy of third-order interpolation. Our result shows that our algorithm has less numerical dissipation than that of linear advection solver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.6
• /
• pp.825-834
• /
• 1999

In this paper we derive the probability density function of the phase error and that of the envelope of the received signal over Nakagami fading channel. Using the new probability density functions we analyze the performance of coherent BPSK, noncoherent FSK, DPSK and noncoherent ASK on Nakagami fading by means of new methods.