• 대한암한의학회지
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• 제20권1호
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• pp.11-21
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• 2015

Objectives : The cancer incidence and cancer burden is increasing. In addition, the use of botanical agents in cancer care is increasing. This article aims to review a research strategy for botanical agents. Methods : The clinical studies of anticancer botanical agents and the papers about clinical research methodology of botanical agents were reviewed. Results : In phase I study, safety confirmation, optimal dose determination and drug interaction study are important. Most botanical agents have low toxicity and some have non-monotone dose response. Therefore, dose-response curve must be evaluated separately from the dose-toxicity curve to determine optimal dose. Although anticancer botanical agents can't shrink tumor size rapidly, they do extend survival. So, in phase II study, response should be evaluated by the survival. Conclusions : Clinical research of botanical agents in cancer is different from traditional methods and strategies. Considering the characteristics of botanical agents and experimental mechanism is necessary in conducting botanical based clinical trials.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.431-438
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• 2009

A Large Eddy Simulation (LES) of the flow in an inducer is carried out under flow rate oscillations. The present study focuses on the dynamic response of the backflow and the unsteady pressure performance to the flow rate fluctuations under non-cavitation conditions. The amplitude of angular momentum fluctuation evaluated by LES is larger than that evaluated by RANS. However, the phase delay of backflow is nearly the same as RANS calculation. The pressure performance curve exhibits a closed curve caused by the inertia effect associated with the flow rate fluctuations. Compared with simplified one dimensional evaluation of the inertia component, the component obtained by LES is smaller. The negative slope of averaged performance curve becomes larger under unsteady conditions. From the conservations of angular momentum and energy, an expression useful for the evaluation of unsteady pressure rise was obtained. The examination of each term of this expression show that the apparent decrease of inertia effects is caused by the response delay of Euler's head and that the increase of negative slope is caused by the delay of inertial term associated with the delay of backflow response. These results are qualitatively confirmed by experiments.

• Geomechanics and Engineering
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• 제30권4호
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• pp.363-372
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• 2022

One of the most frequent issues in tunnel excavation is the collapse of rock blocks and the dropping of rock fragments from the tunnel face. The tunnel face can be reinforced using a number of techniques. One of the most popular and affordable solutions is the use of face longitudinal dowels, which has benefits including high strength, flexibility, and ease of cutting. In order to examine the reinforced face, this work shows the longitudinal deformation profile and ground response curve for a tunnel face. This approach is based on assumptions made during the analysis phase of problem solving. By knowing the tunnel face response and dowel behavior, the interaction of two elements can be solved. The rock element equation derived from the rock bolt method is combined with the dowel differential equation to solve the reinforced ground response curve (GRC). With a straightforward and accurate analytical equation, the new differential equation produces the reinforced displacement of the tunnel face at each stage of excavation. With simple equations and a less involved computational process, this approach offers quick and accurate solutions. The FLAC3D simulation has been compared with the suggested analytical approach. A logical error is apparent from the discrepancies between the two solutions. Each component of the equation's effect has also been described.

• Structural Engineering and Mechanics
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• 제58권2호
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• pp.327-345
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• 2016

Many experimental and analytical studies have been conducted with beam-column subassemblages composed of a two-span beam to investigate the progressive collapse resistance of RC frames. Most study results reveal a strength-decreased transition phase in the nonlinear static load-deflection curve, which may induce dynamic snap-through response and increase the chord rotation demand for effective catenary action (ECA). In this study, the nonlinear static response is idealized as a piecewise linear curve and analytical pseudo-static response is derived for each linearized region to investigate the rotation demands for the ECA of the two-span RC beams. With analytical parameters determined from several published test results, numerical analysis results indicate that the rotation demand of 0.20 rad recommended in the design guidelines does not always guarantee the ECA. A higher rotation demand may be induced for the two-span beams designed with smaller span-to-depth ratios and it is better to use their peak arch resistance (PAR) as the collapse strength. A tensile reinforcement ratio not greater than 1.0% and a span-to-depth ratio not less than 7.0 are suggested for the two-span RC beams bridging the removed column if the ECA is expected for the collapse resistance. Also, complementary pseudo-static analysis is advised to verify the ECA under realistic dynamic column loss even though the static PAR is recovered in the nonlinear static response. A practical empirical formula is provided to estimate an approximate rotation demand for the ECA.

• 한국지반공학회지:지반
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• 제13권1호
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• pp.111-122
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• 1997

표면파를 이용하여 지반의 강성을 추정하는 기법인 SASW 시험에서 위상속도(phase volocity)를 결정하기 위해서는 위상각(phase angle)의 전개(unwrapping)가 필수적이다. 포장 구조에서처럼 깊이에 따라 강성의 차이가 현저한 경우는 기존의 위상각 전개방식으조는 정확한 위상속도를 결정하기가 용이하지 않다. 이는 기존의 위상각 전개방식은 주위상각(principal phase angle)에 2n의 정수배를 더하는 것인데, 위상각 스펙트럼(phase spectrum)에서 정수배를 결정하는 데에 어려움이 있기 때문이다. 본 연구에서는 이러한 문제점을 해결하기 위해서, 임펄스 응답 필터 기법(Impulse Response Filtration Technique), 또는 IRF기법이라고 하는 새로운 위상각 분석 기법을 제안하였다. IRF 기법의 원리는 임펄스 응답을 필터 처리함으로써 파군(wave group)을 분리하는 것인데,파군의 분리는 임펄스 응답에 대한 Gabor spectrogram을 분석한 정보를 근거로 한다. Gabor spectrogram은 전파되는 파의 에너지를 주파수-시간 공간에서 나타내는 contour 그림으로서, 파군의 전파 상황을 시각적으로 표현하는 수단이다. 이렇게 필터 처리된 임펄스 응답을 이용하면, 위상각 스펙트럼의 분석을 정확하게 할 수 있으며, 위상각의 전개에 있어서 난해함을 제거할 수 있다. 끝으로, 전쳔적인 포장 구조에 대하여 이론적으로 SASW 시험을 모사하였으며, 그 결과를 이용하여 IRF기법의 효용성을 입증하였다.

• 전기학회논문지
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• 제56권2호
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• pp.396-406
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• 2007

In this paper, we proposed development of improved model reduction and design of hierarchical controller using reduction model. The model reduction is considered that it is the transient response and the steady-state response through the use of nyquist curve. The hierarchical controller selected tuning of PID controller to ensure specified gain and phase margin and hybrid smith-predictor fuzzy controller using reduction model. Simulation examples are given to show the better performance of the proposed method than conventional methods.

• 한국동물학회지
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• 제35권4호
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• pp.509-517
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• 1992

LiCl (0.047 M)은 Goldhamster의 활동주기 (T)를 평균 1.6시간 연장시키고, 동물 중 20%엑서 단축되는 것으로도 관찰되었다. 1시간 통안의 빛자극(75 Lux)에 의해 주기현상 시점 변화가 나타나는 데 LICI에 의해서 0.3 h 더욱 delav되었고 advance 현상은 1.5 h 감소되었으며 delay엔h advance 전환시기는 1시간 늦게 나타났다. 반면에 7 Lux의 빛 자극에서는 delay가 2.4시간으로 더 증가되었으며 advance 현상은 2.6시간으로 저하되었고, 30분 늦게 delay에서 advance로 전환되었다. subjective day 동안에는 빛자극에 의한 LiCl 효과가 전혀 보이지 않았다. Phase-Response-Curve(PRC)는 Circadian Time에서 delay-advance로 전환되는 mid-subjective night에 점진적으로 변화되는 weak phase curve로 형성되었다. 이 PRC에서 Li이 빛에 대한 민감성을 둔화시키는 효과를 볼 수 있다.

• 한국전문물리치료학회지
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• 제9권3호
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• pp.39-46
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• 2002

In this study, vertical acceleration of center of mass was observed along normal gait phases in 9 healthy male volunteers (aged $25.7{\pm}2.18$). The developed wireless accelerometric device was attached on the intervertebral space between L3 and L4 using a semi-elastic waist belt. A three-dimensional motion analysis system, synchronized with the accelerometry, was used for detecting gait phases. There was no significant correlation between the body weight and the acceleration. The first peak curve covered loading response phase. The second downward peak point was matched accurately with the opposite toe-off. In mid-stance and terminal stance, the acceleration curve highly resembled the vertical ground reaction force curve. There was no significant difference in timing between the final upward peak point and the initial contact. Therefore, the developed accelerometry system would be helpful in determining determine temporal gait pattems in patients with gait disorders.

• 한국통신학회논문지
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• 제23권5호
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• pp.1372-1383
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• 1998

본 논문에서 수행된 DFB(distributed feedback)-LD(laser diode)의 DC와 AC 특성 분석을 위한 모델링은 레이저 다이오드 공진기 내의 spatial hole burning과 $\lambda$/4 위상천이 된 회절 격자의 영향을 고려한 것으로서 DC특성 분석을 위한 시뮬레이션을 통하여 공진기내의 광파워 분포와 캐리어 밀도 분포 그리고 광-전류 곡선등을 얻었으며, AC 특성 분석을 위한 시뮬레이션으로부터는 비교적 정확한 IM 응답과 FM의 위상과 크기 응답을 얻었다.

• 대한기계학회논문집
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• 제13권1호
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• pp.67-76
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• 1989

본 논문에서는 표면거칠기 측정에 있어 70% 이상을 차지하는 촉침식을 이용하여 필터의 cut-off치와 위상특성에 따른 표면거칠기 값의 변화와 필터의 선택에 따른 장점 및 문제점에 대하여 알아보고자 한다.