• The Korean Journal of Physiology and Pharmacology
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• 제15권6호
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• pp.371-382
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• 2011

We performed experiments using Aplysia neurons to identify the mechanism underlying the changes in the firing patterns in response to temperature changes. When the temperature was gradually increased from $11^{\circ}C$ to $31^{\circ}C$ the firing patterns changed sequentially from the silent state to beating, doublets, beating-chaos, bursting-chaos, square-wave bursting, and bursting-oscillation patterns. When the temperature was decreased over the same temperature range, these sequential changes in the firing patterns reappeared in reverse order. To simulate this entire range of spiking patterns we modified nonlinear differential equations that Chay and Lee made using temperature-dependent scaling factors. To refine the equations, we also analyzed the spike pattern changes in the presence of potassium channel blockers. Based on the solutions of these equations and potassium channel blocker experiments, we found that, as temperature increases, the maximum value of the potassium channel relaxation time constant, ${\tau}_n(t)$ increases, but the maximum value of the probabilities of openings for activation of the potassium channels, n(t) decreases. Accordingly, the voltage-dependent potassium current is likely to play a leading role in the temperature-dependent changes in the firing patterns in Aplysia neurons.

• 사회복지연구
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• 제37호
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• pp.117-144
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• 2008

본 연구의 목적은 한국 복지국가의 지출변화를 추동하는 요인에 대한 이론적 가설들을 실증적으로 분석하는 것이 목적이다. 한국복지국가 지출결정요인을 분석하는 기존연구들은 종속변수로 사용되는 사회복지지출 자료의 신뢰성, 분석방법의 타당성을 충분히 확보하고 있지 못했다는 한계를 가지고 있다. 또한 분석시기가 1990년대 말까지만을 포괄하고 있어서, 최근의 한국복지국가 변화를 충분히 반영하지 못하고 있다. 본 연구는 1960년 이후부터 2003년까지를 분석에 포함하며, 일관된 기준을 가지고 구축된 '비교 사회정책 데이터(Comparative Social Policy Data set)'를 활용하고, 분석방법으로서 일반화최소제곱(GLS) 방식의 시계열 회귀분석을 사용함으로써 기존 연구의 한계를 극복하고자 하였다. 본 연구의 분석 결과는 첫째, 구조기능주의, 특히 산업화와 관련된 변수들이 가장 안정적이고 통계적으로 유의미하였다. 둘째, 실업률 변수의 영향은 독점자본주의의 심화를 반영한 결과라기보다는 경제위기 이후 실업의 증가에 대한 정부의 단기적 대응 결과로 해석하는 것이 타당하다. 셋째, 권력자원론 변수인 좌파정치의 한국적 적용은 매우 제한적으로만 타당한 것으로 분석된다. 결론적으로 한국복지국가의 발전에서 진보정치 영향력의 일면이 발견되긴했지만, 보다 정확한 결론을 위해서는 조금 더 관찰이 필요하며, 한국의 복지국가는 산업화론이 적용되는 초보적이고 자동적인 성장으로 특징 지워진다고 할 수 있다.

• Communications for Statistical Applications and Methods
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• 제25권4호
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• pp.443-451
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• 2018

$P^M_{\lambda}$-service policy is a workload dependent hysteretic policy. The policy has two service states comprised of the ordinary stage and the fast stage. An ordinary service stage is initiated by the arrival of a customer in an idle state. When the workload of the server surpasses threshold ${\lambda}$, the ordinary service stage changes to the fast service state, and it continues until the system is empty. These service stages alternate in this manner. When the cost of changing service stages is high, the hysteretic policy is more efficient than the threshold policy, where a service stage changes immediately into the other service stage at either case of the workload's surpassing or crossing down a threshold. $P^M_{\lambda}$-service policy is a modification of $P^M_{\lambda}$-policy proposed to control finite dams, and also an extension of the well-known D-policy. The distributions of the stationary workload of $P^M_{\lambda}$-service policy and its variants are studied well. However, there is no known result on the sojourn time distribution. We prove that there is a relation between the sojourn time of a customer and the first up-crossing time of the workload process over the threshold ${\lambda}$ after the arrival of the customer. Using the relation and the duality of M/G/1 and G/M/1 queues, we obtain conditional sojourn time distributions in M/G/1 and G/M/1 queues under the policy.

• 제어로봇시스템학회논문지
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• 제10권12호
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• pp.1148-1154
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• 2004

The goal of this paper is to verity that the gradual reduction of drug dose (GRDD), which has already been shown by authors to be effective for a simplified HIV infection model, still works for a more realistic model. While the simplified HIV infection model does not take into account an helper-independent CTL, the five state nonlinear model proposed by Wodarz describes the dynamics of both helper-dependent and helper-independent CTL in HIV infection. In this paper, it is shown that, by applying GRDD to Wodarz's five state HIV infection model, the state of HIV infected patient converges to that of non-progressor whose immune response is excited so that his symptom would not be developed into AIDS. Roughly speaking, GRDD is 'slow reduction of dose after the maximum dose for a certain period.' It turns out that an equilibrium representing non-progressor is locally asymptotically stable for the most values of drug dosage, which is required to hold in order to apply GRDD. Simulation results establish that GRDD is still considerably effective both for an AIDS patient and a patient who has been on HAART for a long time.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.308-313
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• 2005

For a real-time quadruped robot running control, there are many important objectives to consider. In this paper, the running control architecture based on global states, which describe the cyclic target motion, and central pattern is proposed. The main goal of the controller is how the robot can have robustness to an unpredictable environment with reducing calculation burden to generate control inputs. Additional goal is construction of a single framework controller to avoid discontinuities during transition between multi-framework controllers and of a training-free controller. The global state dependent neuron network induces adaptation ability to an environment and makes the training-free controller. The central pattern based approach makes the controller have a single framework, and calculation burden is resolved by extracting dynamic equations from the control loop. In our approach, the model of the quadruped robot is designed using anatomical information of a cat, and simulated in 3D dynamic environment. The simulation results show the proposed single framework controller is robustly performed in an unpredictable sloped terrain without training.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2151-2157
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• 2010

Spectroscopic and quantum mechanical studies of the Et3PAuCl complex were performed to characterize the effect of aurophilicity on the optical properties. When excited with UV light at low temperature, the crystalline complex produced a deep luminescence in both the blue (high-energy) and red (low-energy) regions of the spectrum. The intensity of the low-energy luminescence was markedly reduced in the powdered state and quenched in the solution state. Time-dependent density functional theory (TD-DFT) calculations on electronic structures of both the ground and excited states of aggregates $[Et_3PAuCl]_n$ (n = 1 - 3) indicated that the low-energy luminescence was attributable to Au-centered transitions, which are significantly affected by aurophilic interactions. By contrast, the high-energy luminescence appeared to be independent of the state of the complex and was strongly associated with the charge transfer from Cl to Au.

• Journal of Power Electronics
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• 제11권4호
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• pp.471-478
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• 2011

This paper addresses the establishment of a kVA-range plug-in hybrid electrical vehicle (PHEV) integration test platform and associated issues. Advancements in battery and power electronic technology, hybrid vehicles are becoming increasingly dependent on the electrical energy provided by the batteries. Minimal or no support by the internal combustion engine may result in the vehicle being occasionally unable to recharge the batteries during highly dynamic driving that occurs in urban areas. The inability to sustain its own energy source creates a situation where the vehicle must connect to the electrical grid in order to recharge its batteries. The effects of a large penetration of electric vehicles connected into the grid are still relatively unknown. This paper presents a novel methodology that will be utilized to study the effects of PHEV charging at the sub-transmission level. The proposed test platform utilizes the power hardware-in-the-loop (PHIL) concept in conjunction with high-fidelity PHEV energy system simulation models. The battery, in particular, is simulated utilizing a real-time digital simulator ($RTDS^{TM}$) which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces via a LC-LC-type filter to a power grid. In addition, the PHEV impact is evaluated via another power electronic converter controlled through $dSPACE^{TM}$, a rapid control systems prototyping software.

• 한국통신학회논문지
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• 제14권2호
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• pp.155-163
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• 1989

단일 링크 유연성 로보트 팔의 제어를 위해서 가정 모드 방법으로 유도된 동 특성 모델링에 QUADRATIC-최적제어 이론을 적용하였다. 이 제어 기법에 대한 제어 루우프 구성에는 모든 상태값의 피이트 백을 필요로 하지만 유연성 팔에 있어서 모드형태의 시 종속 변화율은 직접 출력으로부터 피이드백 될수 없기 때문에 최적 제어기를 실현하기 위해서는 상태 추정기의 도입이 필요하게 된다. 특히 시스템에 외란이나 측정에 노이즈가 발생할 때는 확률 추정 방법을 적용해서 상태를 추정해야 하는데 이를 위해서 칼만 필터를 사용하였다. 상태 추정기를 이용한 유연성 메니퓨레이터 팔의 시스템 모델을 모든 상태 값이 직접 측정될 수 있다고 가정한 유연성 시스템 모델과 시뮤레이션을 통해서 비교하였다.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.659-667
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• 2017

Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

• Asian-Australasian Journal of Animal Sciences
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• 제32권5호
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• pp.629-636
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• 2019

Objective: The study was designed to determine the cytotoxic effect of gallic acid (GA), obtained by the hydrolysis of tannins, on mice TM4 Sertoli cells apoptosis. Methods: In the present study, non-tumorigenic mice TM4 Sertoli cells were treated with different concentrations of GA for 24 h. After treatment, cell viability was evaluated using WST-1, mitochondrial dysfunction, cells apoptosis and necrosis was detected using JC-1, Hoechst 33342 and propidium iodide staining. The expression levels of Cyclin B1, proliferating cell nuclear antigen (PCNA), Bcl-2-associated X protein (BAX), and Caspase-3 were also detected by quantitative real-time polymerase chain reaction and Western-blotting. Results: The results showed that 20 to $400{\mu}M$ GA inhibited viability of TM4 Sertoli cells in a dose-dependent manner. Treatment with $400{\mu}M$ GA significantly inhibited PCNA and Cyclin B1 expression, however up-regulated BAX and Caspase-3 expression, caused mitochondrial membrane depolarization, activated Caspase-3, and induced DNA damage, thus, markedly increased the numbers of dead cells. Conclusion: Our findings showed that GA could disrupt mitochondrial function and caused TM4 cells to undergo apoptosis and necrosis.