• 한국안광학회지
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• 제16권3호
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• pp.283-291
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• 2011

목적: 지수감소곡선을 이용하여 착색렌즈에서의 착색시간과 시감투과율 사이의 관계를 대표할 수 있는 실험적 맞춤곡선(empirical fitting curve)을 도출한다. 방법: CR-39 렌즈와 6가지 색상의 염료를 이용하여 총 90개의 착색렌즈를 제조하였고, 실험적 맞춤곡선을 구하기 위한 시험곡선(trial curve)으로서 단일(single), 2중(double) 및 3중(triple) 지수감소곡선(exponential decay curve)을 이용한다. 결과: 최적의 실험적 맞춤곡선은 3중 지수감속곡선인 것으로 밝혀졌다. 결론: 착색시간에 따른 시감투과율의 변화를 대표하는 적절한 실험적 맞춤곡선으로서 3중 지수감소곡선을 제안한다.

• Smart Structures and Systems
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• 제18권6호
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• pp.1203-1215
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• 2016

When strain sensing cables are under long-term stress and cyclic loading, creep may occur in the jacket material and each layer of the cable structure may slide relative to other layers, causing fatigue in the cables. This study proposes a device for testing the fatigue characteristics of three types of cables operating under different conditions to establish a decay model for observing the patterns of strain decay. The fatigue characteristics of cables encased in polyurethane (PU), GFRP-reinforced, and wire rope-reinforced jackets were compared. The findings are outlined as follows. The cable strain decayed exponentially, and the decay process involved quick decay, slow decay, and stabilization stages. Moreover, the strain decay increased with the initial strain and tensile frequency. The shorter the unstrained period was, the more similar the initial strain levels of the strain decay curves were to the stabilized strain levels of the first cyclic elongation. As the unstrained period increased, the initial strain levels of the strain decay curves approached those of the first cyclic elongation. The tested sensing cables differed in the amount and rate of strain decay. The wire rope-reinforced cable exhibited the smallest amount and rate of decay, whereas the GFRP-reinforced cable demonstrated the largest.

• 한국안광학회지
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• 제5권2호
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• pp.145-150
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• 2000

망막의 광원에 대한 순응은 간상체-추상체에 의해 시간에 따라 명순응-암순응의 2개 곡선으로 이루어진다. 시간에 따른 순응도는 역치를 측정하여 얻어지며 분절점을 중심으로 2개의 감소 곡선이 된다. 암순응은 $T_{min}$, $a_r$, $a_c$, $T_{0(r)}$, $T_{0(c)}$, $t_b$, $t_c$의 파라미터로 이루어진 exponential decay 함수로 표현 할 수 있다. $t_b$ 이하의 곡선은 추상체의 순응 민감도 곡선이고 $t_b$ 이상 곡선은 간상체의 순응 민감도를 나타낸다. Exponential decay 함수는 망막 위치에 따른 순암순응 시표의 각도에 따른 암순응, 조명 크기에 따른 암순응, 나이에 따른 암순응 등의 암순응 함수에 잘 적용되었다. Decay parameter가 암순응 함수의 성질을 표현할 수 있어 지표로써 사용할 수 있다.

• 반도체디스플레이기술학회지
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• 제11권1호
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• pp.35-39
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• 2012

$YAlO_3:Tb{_x}^{3+}$ has been synthesized by a combustion process and the concentration x of Tb was varied from 0.001 and 0.05 mol% per mole of $YAlO_3$. The emission optical properties on the $YAlO_3:Tb{_x}^{3+}$ have been investigated by time-resolved photoluminescence spectra and decay curves of center wavelength. The emission color changes from blue to green with increasing the $Tb^{3+}$ concentration from x= 0.001 to 0.05 mole fraction in $YAlO_3$ host. This emission color change can be explained in terms of cross-relaxation processes. Decay curves of emission intensity indicate that the type of energy transfer is donor-acceptor transition.

• The Korean Journal of Ceramics
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• 제4권1호
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• pp.28-32
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• 1998

This paper reports on photoluminescence (PL), luminescence decay curves, and compositional analysis of porous silicon(PS) which is aged under air ambient by Fourier transform infrared vibrational spectroscopy (FTIR) and by Auger electron spectroscopy (AES). Porous silicos which has been aged under air ambient yields two PL band structures, i.e. blue/violet PL and red PL. The evolution of a blue/violet band is pronounced, especially for thin PS film which is prepared in dilute HF solution. The blue/violet PL band has been observed initially to increrase rapidly with aging, then saturated with further atmospheric aging. The ambient air aged PS exhibits a fast decay time of sub-nanosecond at room temperature and shows appreciably faster decay time than that at 20K. Atmospheric aging of this thin blue/violet luminescing PS yield non-stoichiometric oxide judging from the vibrational spectra of Si-O and AES analysis.

• 한국수산과학회지
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• 제25권3호
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• pp.219-228
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• 1992

와편모조류, 남조류, Chloromonadophyceae와 Cryptophyceae를 포함한 12종의 해양 식물플랑크톤의 일차적 형광특성을 in vivo 상태에서 조사하였다. 형광과 exciatation 스펙트럼을 측정한 결과 약 380-435nm 영역에서 강한 세기의 형광 스펙트럼이, 조사된 모든 식물플랑크톤으로부터 얻어졌다. 식물플랑크톤의 성장 상태의 변화에 따른 형광 스펙트럼의$\lambd_{max}$에 대한 영향을 관찰하였다. 관찰된 형광 스펙트럼의 형광소를 밝히기 위하여, 식물플랑크톤의 구성성분 중에 유사한 형광 특성을 보이는 8가지 pteridine계 화합물의 phosphate 완충용액에 대한 형광 특성과 식물플랑크톤의 380-435nm 영역에서 나타난 스펙트럼의 세기와 모양, $\lambd_{max}$를 비교하였다. 식물플랑크톤의 fluorescence lifetime$(\tau)$과 fluorescence decay curve를 식물플랑크톤에 존재하는 유기화합물들의 표준용액의 $\tau$값과 비교하였다. 430 nm의 들뜨기 파장을 사용하여 얻은 식물플랑크톤의 fluorescence decay는 biexponential과 triexponential decay를 보였다. 박테리아와 식물플랑크톤의 형광 특성을 비교한 결과 형광 스펙트라뿐 아니라 붕괴 양상도 현저한 차이점을 보였다.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.13-17
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• 2015

$YAlO_3:Tb{_x}^{3+}$ has been synthesized by a combustion process and the concentration x of Tb was varied from 0.001 and 0.05 mol% per mole of YAlO3. The energy transfer of $^5D_3{\rightarrow}^7F_6$(385nm) and $^5D_4{\rightarrow}^7F_5$(544nm) transitions on the $YAlO_3:Tb{_x}^{3+}$(x =0.001, 0.05) have been investigated by using decay curves. The energy transfer mechanism was explained by Inokuti and Hirayama model. The results of calculation and fitting showed that values of n are 6.11(x=0.01) and 6.13(x=0.005). These indicate that the energy transfer mechanism between $Tb^{3+}$ ions is dipole-dipole interaction.

• Structural Engineering and Mechanics
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• 제33권6호
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• pp.725-745
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• 2009

In this paper, probabilistic seismic performance assessment of a typical non-seismic RC frame building representative of a large inventory of existing buildings in developing countries is conducted. Nonlinear time-history analyses of the sample building are performed with 20 large-magnitude medium distance ground motions scaled to different levels of intensity represented by peak ground acceleration and 5% damped elastic spectral acceleration at the first mode period of the building. The hysteretic model used in the analyses accommodates stiffness degradation, ductility-based strength decay, hysteretic energy-based strength decay and pinching due to gap opening and closing. The maximum inter story drift ratios obtained from the time-history analyses are plotted against the ground motion intensities. A method is defined for obtaining the yielding and collapse capacity of the analyzed structure using these curves. The fragility curves for yielding and collapse damage levels are developed by statistically interpreting the results of the time-history analyses. Hazard-survival curves are generated by changing the horizontal axis of the fragility curves from ground motion intensities to their annual probability of exceedance using the log-log linear ground motion hazard model. The results express at a glance the probabilities of yielding and collapse against various levels of ground motion intensities.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1987년도 학술발표회 논문집
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• pp.34-38
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• 1987

• Structural Engineering and Mechanics
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• 제16권4호
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• pp.405-422
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• 2003

Scaled brick masonry panels were tested under cyclic unialxial compression loading to evaluate its deformation characteristics. An envelope stress - strain curves, a common point curves and stability point curves were obtained for various cyclic test conditions. Loops of the stress-strain hysteresis were used to determine the energy dissipation for each cycle. Empirical expressions were proposed for the relations between energy dissipation and envelope and residual strains. These relations indicated that the decay of masonry strength starts at about two-third of peak stress.