• Steel and Composite Structures
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• 제23권5호
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• pp.493-499
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• 2017

The behaviour of steel frames is highly influenced by the beam-column connections. Traditionally, Steel frames were usually designed assuming that connections are ideally pinned or fully rigid. A semi-rigid connection, however, creates a balance between the two extreme approaches mentioned above. In this research, two full scales of Extended End Plate Connections (EEPCs) were tested. Mathematical and numerical models were used to analyse the connections, and close correlations were found between these models and the corresponding tested specimens, which confirmed the confidence in the experimental results. The experimental results obtained enrich the available test data about behaviour of EEPC. In addition, the purpose of studying EEPC experimentally is to compare the stiffness and moment-rotation curve of EEPCs with that of Cap Plate Connections (CPCs), which were tested in a previous work. CPCs have not been studied sufficiently in the literature. The results obtained show that the typical CPC reduces the connection stiffness and these results will make a valuable contribution to the available test data in the research area of CPC.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1212-1217
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• 한국전자파학회논문지
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• 제14권12호
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• pp.1335-1340
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• 2003

본 논문에서는 쇼트키 장벽 빔 리드 다이오드와 180$^{\circ}$hybrid coupler를 이용하여 24 GHz 대역에서 동작하는 단일 평형 다이오드 주파수 혼합기를 설계 및 제작하였다. 근거리 차량의 거리와 속도 탐지용 호모다인 FMCW 레이더의 용도에 적합하도록 대역폭은 100MHz이내에서 작은 LO 구동 전력으로 IF 출력 주파수의 변환손실은 가능한 작고 평탄도는 일정하도록 그리고 LO 격리도가 가능한 크도록 하였다. LO 포트의 반사손실, LO 격리도, 변환손실 성능 특성간에 최적의 성능을 위하여 다이오드의 정합회로, 그리고 결합기와 정합회로 사이의 embedded 마이크로스트립 선로를 이용하여 최적화하였다. 제작된 혼합기는 6 dBm의 LO 구동 전력을 가지고 변환손실 6 dB, LO/RF 격리도 23 dB, P1 dB(input)는 3 dBm의 결과를 얻었다.

• Current Optics and Photonics
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• 제4권3호
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• pp.221-228
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• 2020

We developed an all-fiber RGB laser light source module for application in an automobile head-up display. It is based on laser diodes and an optical fiber combiner that substantially enhances the flexibility of configuration and stability against harsh working conditions for automobiles. We coupled 13 laser diodes with optical fibers and merged them into a single output with a beam combiner device. Red (R), green (G), and blue (B) laser sources were employed to produce primary colors that were mixed into a white light output. An optical output power of approximately 1.5 W was achieved, and the color balance of the output lights was assessed based on the CIE 1931 color space. The optical output power was shown to be stable for over 160 h within an optical fluctuation of less than 0.27%.

• 건축역사연구
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• 제29권1호
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• pp.39-49
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• 2020

A dapo type bracket system which consists of chuganpo(柱間包) and chusangpo(柱上包) with a fake-beam adopted a nemok-dori member to cope with oemok-dori member in order to obtain balance between the outer-side and the inner-side of the bracket system. The middle part of the longest rater in the dapo system is supported by three points made by oemok-dori, jusim-dori and nemok-dori members and the area between the rafer supporting points forms a supporting area. The increase of rafter supporting points and supporting area leads to heightening the structural stability and the efficiency of load delivery. In the eave of dapo system the portion where the three supporting points formed by oemok-dori, jusim-dori and nemok-dori members shows as 33% in the early period, 71% in the middle period and 78% in the later period. On the contrary the portion where more than one of the three dori members were omitted shows as 67% in the early period, 29% in the middle period and 22% in the later period. This is the result of the increase of the number and the distance of steps in the dapo bracket system as time goes on. This is because the structural role of three supporting points becomes important as the increase of distance between the dori members leads to the increase of load which burdens on each dori member.

• Journal of Chest Surgery
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• 제53권4호
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• pp.184-190
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• 2020

Radiation therapy (RT) has improved patient outcomes, but treatment-related complication rates remain high. In the conventional 2-dimensional and 3-dimensional conformal RT (3D-CRT) era, there was little room for toxicity reduction because of the need to balance the estimated toxicity to organs at risk (OARs), derived from dose-volume histogram data for organs including the lung, heart, spinal cord, and liver, with the planning target volume (PTV) dose. Intensity-modulated RT (IMRT) is an advanced form of conformal RT that utilizes computer-controlled linear accelerators to deliver precise radiation doses to the PTV. The dosimetric advantages of IMRT enable better sparing of normal tissues and OARs than is possible with 3D-CRT. A major breakthrough in the treatment of esophageal cancer (EC), whether early or locally advanced, is the use of proton beam therapy (PBT). Protons deposit their highest dose of radiation at the tumor, while leaving none behind; the resulting effective dose reduction to healthy tissues and OARs considerably reduces acute and delayed RT-related toxicity. In recent studies, PBT has been found to alleviate severe lymphopenia resulting from combined chemo-radiation, opening up the possibility of reducing immune suppression, which might be associated with a poor prognosis in cases of locally advanced EC.

• 한국IT서비스학회:학술대회논문집
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• 한국IT서비스학회 2003년도 추계학술대회
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• pp.616-623
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• 2003

Since the computing environment changes very rapidly, the estimation of software effort is very difficult because it is not easy to collect a sufficient number of relevant cases from the historical data. If we pinpoint the cases, the number of cases becomes too small. However if we adopt too many cases, the relevance declines. So in this paper we attempt to balance the number of cases and relevance. Since many researches on software effort estimation showed that the neural network models perform at least as well as the other approaches, so we selected the neural network model as the basic estimator. We propose a search method that finds the right level of relevant cases for the neural network model. For the selected case set, eliminating the qualitative input factors with the same values can reduce the scale of the neural network model. Since there exists a multitude of combinations of case sets, we need to search for the optimal reduced neural network model and corresponding case set. To find the quasi-optimal model from the hierarchy of reduced neural network models, we adopted the beam search technique and devised the Case-Set Selection Algorithm. This algorithm can be adopted in the case-adaptive software effort estimation systems.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.30-45
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• 2013

The present work focuses on the unsteady aerodynamics and aeroelastic properties of a small-medium sized wind-turbine blade operating under ideal conditions. A tapered/twisted blade representative of commercial blades used in an experiment setup at the National Renewable Energy Laboratory is considered. The aerodynamic loads are computed using Computational Fluid Dynamics (CFD) techniques. For this purpose, FLUENT$^{(R)}$, a commercial finite-volume code that solves the Navier-Stokes and the Reynolds-Averaged Navier-Stokes (RANS) equations, is used. Turbulence effects in the 2D simulations are modeled using the Wilcox k-w model for validation of the CFD approach. For the 3D aerodynamic simulations, in a first approximation, and considering that the intent is to present a methodology and workflow philosophy more than highly accurate turbulent simulations, the unsteady laminar Navier-Stokes equations were used to determine the unsteady loads acting on the blades. Five different blade pitch angles were considered and their aerodynamic performance compared. The structural dynamics of the flexible wind-turbine blade undergoing significant elastic displacements has been described by a nonlinear flap-lag-torsion slender-beam differential model. The aerodynamic quasi-steady forcing terms needed for the aeroelastic governing equations have been predicted through a strip-theory based on a simple 2D model, and the pertinent aerodynamic coefficients and the distribution over the blade span of the induced velocity derived using CFD. The resulting unsteady hub loads are achieved by a first space integration of the aeroelastic equations by applying the Galerkin's approach and by a time integration using a harmonic balance scheme. Comparison among two- and three- dimensional computations for the unsteady aerodynamic load, the flap, lag and torsional deflections, forces and moments are presented in the paper. Results, discussions and pertinent conclusions are outlined.

• 한국소음진동공학회논문집
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• 제16권3호
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• pp.283-290
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• 2006

이 연구는 알고 있는 단일 주기를 갖는 정적 및 주기적 외란의 제거에 대해서 다룬다. 자기력 부상시스템에서 외란력을 능동적으로 제거하기 위해서는 제어 입력이 두 가지 다른 이득 값을 가져야 한다. 하나는 시스템의 안정적 제어를 위한 부분이고 다른 하나는 외부로부터 시스템에 영향을 미치는 외란력의 제거를 위한 부분이다. 본 논문에서는 평형 빔을 안정 적으로 제어하기 위해서 간단한 상태 궤환 제어기를 채용하며, 외부로부터 시스템에 영향을 미치는 외란 성분을 추정하기 위해서 선형 관측기를 채용한다. 또한 자속의 궤환에 의해서 구성된 제어 전류는 관측기에 의해서 관측된 외란력과 외란력을 억제하려는 전자석의 힘의 차로 나타나며 이들 관계는 선형성을 유지한다. 이 선형성은 본질적으로 비선형성을 갖고 있는 자기력 부상 시스템에 대한 수치 해석적 용이함을 제공하며 이 논문에서 다루는 정적 및 주기외란의 제거를 위해서 우수한 성능을 발휘한다. 모의시험 결과는 제안된 제어 기법에 의한 정적 및 주기적 외란의 제거를 입증한다.

• Journal of Korean Neurosurgical Society
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• 제38권1호
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• pp.41-46
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• 2005

Objective : A study of the histopathologic and neurobehavioral correlates of cortical impact injury produced by increasing impact velocity using the controlled cortical impact[CCI] injury model is studied. Methods : Twenty-four Sprague-Dawley rats [$200{\sim}250g$] were given CCI injury using a pneumatically driven piston. Effect of impact velocity on a 3mm deformation was assessed at 2.5m/sec [n=6], 3.0m/sec [n=6], 3.5m/sec [n=6], and no injury [n=6]. After postoperative 24hours the rats were evaluated using several neurobehavioral tests including the rotarod test, beam-balance performance, and postural reflex test. Contusion volume and histopathologic findings were evaluated for each of the impact velocities. Results : On the rota rod test, all the injured rats exhibited a significant difference compared to the sham-operated rats and increased velocity correlated with increased deficit [p<0.001]. Contusion volume increased with increasing impact velocity. For the 2.5, 3.0, and 3.5m/sec groups, injured volumes were $18.8{\pm}2.3mm^3$, $26.8{\pm}3.1mm^3$, and $32.5{\pm}3.5mm^3$, respectively. In addition, neuronal loss in the hippocampal sub-region increased with increasing impact velocity. In the TUNEL staining, all the injured groups exhibited definitely positive cells at pericontusional area. However, there were no significant differences in the number of positive cells among the injured groups. Conclusion : Cortical impact velocity is a critical parameter in producing cortical contusion. Severity of cortical injury is proportional to increasing impact velocity of cortical injury.