• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제14권4호
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• pp.225-247
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• 2010

In this paper, we establish a two-competitive-prey and one-predator Holling type II system by introducing a proportional periodic impulsive harvesting for all species and a constant periodic releasing, or immigrating, for the predator at different fixed time. We show the boundedness of the system and find conditions for the local and global stabilities of two-prey-free periodic solutions by using Floquet theory for the impulsive differential equation, small amplitude perturbation skills and comparison techniques. Also, we prove that the system is permanent under some conditions and give sufficient conditions under which one of the two preys is extinct and the remaining two species are permanent. In addition, we take account of the system with seasonality as a periodic forcing term in the intrinsic growth rate of prey population and then find conditions for the stability of the two-prey-free periodic solutions and for the permanence of this system. We discuss the complex dynamical aspects of these systems via bifurcation diagrams.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.539-542
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• 2005

In this study, we investigated the influence of vibrational stimulation on postural control. To study the effect, the sway of the center of pressure was observed fur two different visual conditions and for three different patterns of vibrational stimulation on plantar area. The two visual conditions were normal condition with visual feedback and blind condition with both eyes closed. The three vibrational stimulations were white noise, constant vibration, and vibration with amplitude modulations (sine curve modulation). The experimental results showed that the sway of the center of pressure distinctively reduced with white noise vibrational stimulation. This result showed that it's possible to use vibrational stimulation for improving the ability of postural control.

• 대한기계학회논문집A
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• 제26권3호
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• pp.521-527
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• 2002

In this paper, tensile behavior and low cycle fatigue behavior of 316L stainless steel which is currently favored structural material for several high temperature components such as the liquid metal cooled fast breeder reactor (LMFBR) were investigated. Research was performed at 55$0^{\circ}C$, $600^{\circ}C$ and $650^{\circ}C$ since working temperature of 316L stainless steel in a real field is from 40$0^{\circ}C$ to $650^{\circ}C$. From tensile tests performed by strain controls with $1{\times}10^{-3}/s,\; l{\times}10^{ -4}/s \;and\; 1{\times}10/^{ -5}/ s $ strain rates at each temperature, negative strain rate response (that is, strain hardening decreases as strain rate increases) and negative temperature response were observed. Strain rate effect was relatively small compared with temperature effect. LCF tests with a constant total strain amplitude were performed by strain control with a high temperature extensometer at R.T, 55$0^{\circ}C$, $600^{\circ}C$, $650^{\circ}C$ and total strain amplitudes of 0.3%~0.8% were used and test strain rates were $1{times}10^{-2} /s,\; 1{times}10^{-3} /s\; and\; 1{times}10^{-4} /s$. A new energy based LCF life prediction model which can explain the effects of temperature, strain amplitude and strain rate on fatigue life was proposed and its excellency was verified by comparing with currently used models.

• 전력전자학회논문지
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• 제10권1호
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• pp.61-69
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• 2005

NPC 인버터는 많은 수의 전력용 반도체 소자로 구성되어 있으므로 다른 고장의 유형보다 전력용 반도체 스위치의 고장 발생 가능성이 더욱 크다. 고장발생시에 시스템의 연속적인 운전을 위한 대책의 개발은 매우 필요하며, 이러한 고장은 제안된 방법을 이용함으로써 시스템의 고장 허용 능력을 향상할 수 있다. 제안된 방법은 하나의 전력용 반도체 고장발생시 고장난 전력용 반도체가 포함된 고장상을 직렬 연결된 커패시터의 접속점에 연결한 후 나머지 두상을 이용하여 제어함으로써 직류-링크 전압을 유지하고, 일정한 크기를 가지는 출력 부하상전류를 연속적으로 시스템에 공급할 수 있다. 제안된 방법은 몇가지 특별한 분야에서 값비싼 다른 대안책들보다 더 경제적인 대안이다.

• 대한소아치과학회지
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• 제25권4호
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• pp.788-796
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• 1998

The purpose of this study was to investigate the effect of various electroacupuncture duration induced by acupuncture point-Zusanli ($S_{36}$) electrical stimulation on inhibition of amplitude of digastric electromyogram (dEMG) evoked by noxious electrical stimuli around the mental foramen. intraperitoneal sodium pentobarbital in an initial dose of 50mg/kg and maintenance doses of 4.5mg/kg/h were given through a cannula in the femoral vein using a constant infusion pump. A pair of stimulating electrodes were inserted for noxious stimuli around the mental foramen. An irritant electronic stimuli pulse (0.2 Hz, 0.1 ms duration) was produced with an intensity of about $1.5{\times}2$ times threshold for evoking the dEMG. The anterior belly of the digastric muscle was exposed and a pair of 0.1mm wire electrodes were inserted for dEMG recording. Acupuncture point stimulation on Zusanli (2 Hz, 250 ${\mu}s$, biphasic pulse, 2 V) was delivered by Dental Electronic Anesthesia (3M, U.S.A). For periods of electronic stimulation of 10, 20, and 30min, the amplitudes of dEMG were measured on the oscilloscope and on the monitor connected to the amplifier. The following results were obtained: The dEMG was decreased to 73.4% of that in the control set after 10 min electroacupunture stimulation (Group I); The dEMG was decreased to 77.1% (10min), 54.0.% (20min) of that in the control set after 20minutes of electroacupunture stimulation (Group II). The dEMG was decreased to 73.3% (10min), 61.9% (20min), 76.2% (30min) of that in the control set after 30 min of electroacupunture stimulation (Group III). From these results, it may be that in the electroacupuncture stimulation on the Zusnali resulted in a reduction of amplitude of dEMG and that the most effective electroacupuncture stimulation period was 20min.

• 한국도로학회논문집
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• 제17권6호
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• pp.1-9
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• 2015

PURPOSES : The objective of this study is to propose a quality control and quality assurance method for use during asphalt pavement construction using non-destructive methods, such as ground penetrating radar (GPR) and an infrared (IR) camera. METHODS : A 1.0 GHz air-coupled GPR system was used to measure the thickness and in situ density of asphalt concrete overlay during the placement and compaction of the asphalt layer in two test construction sections. The in situ density of the asphalt layer was estimated based on the dielectric constant of the asphalt concrete, which was measured as the ratio of the amplitude of the surface reflection of the asphalt mat to that of a metal plate. In addition, an IR camera was used to monitor the surface temperature of the asphalt mat to ensure its uniformity, for both conventional asphalt concrete and fiber-reinforced asphalt (FRA) concrete. RESULTS : From the GPR test, the measured in situ air void of the asphalt concrete overlay gradually decreased from 12.6% at placement to 8.1% after five roller passes for conventional asphalt concrete, and from 10.7% to 5.9% for the FRA concrete. The thickness of the asphalt concrete overlay was reduced from 7.0 cm to 6.0 cm for the conventional material, and from 9.2 cm to 6.4 cm for the FRA concrete. From the IR camera measurements, the temperature differences in the asphalt mat ranged from $10^{\circ}C$ to $30^{\circ}C$ in the two test sections. CONCLUSIONS : During asphalt concrete construction, GPR and IR tests can be applicable for monitoring the changes in in situ density, thickness, and temperature differences of the overlay, which are the most important factors for quality control. For easier and more reliable quality control of asphalt overlay construction, it is better to use the thickness measurement from the GPR.

• 전자공학회논문지
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• 제51권10호
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• pp.173-179
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• 2014

본 논문에서는 리니어 컴프레서 위치센서리스 스트로크 제어기의 성능 향상을 위해 모터 매개변수 추정 시스템을 구현하였다. 리니어 컴프레서가 적용된 냉장고나 에어컨의 냉각능력을 제어하기 위해서는 단위시간동안 피스톤의 움직인 거리, 즉 피스톤의 속도를 제어해야 하는데 이때 리니어 모터의 주파수나 스트로크를 조정함으로써 가능하다. 이때, 주파수를 고정하고 스트로크를 변화시키는 것이 일반적이다. 스트로크, 즉 피스톤의 행정거리를 정확하게 추정하는 것이 리니어 컴프레서의 동특성을 좌우하는데, 본 연구에서는 모터 매개변수를 추정하는 경우와 상수로 놓았을 경우에 대해 필요한 메모리 공간과 스트로크 오차에 대한 실험 결과를 통해 그 장단점을 확인하였다.

• 대한소아치과학회지
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• 제23권2호
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• pp.525-536
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• 1996

The purpose of this study was to investigate the effect of electrical anesthesia induced by non-acupuncture point stimulation on inhibition of amplitude of digastric EMG evoked by noxious electrical stimuli in teeth and gingiva. Experiments were performed with dogs anesthetized with intraperitoneal pentobarbital sodium in an initial dose of 30mg/kg. Maintenance doses of 4.0ml/hour were given through a cannula in the femoral vein using a constant infusion pump. Anterior belly of digastric muscle was exposed and a pair of 0.1mm wire electrodes were inserted for E.M.G. recording. Bipolar electrodes were inserted into the labial and lingual surface of upper canine and the labial area of upper gingiva. Noxious stimuli were delivered to the tooth and gingiva through those electrodes by electric stimulator. Non-acupuncture point stimulation of 2Hz was delivered bilaterally to the femoral area. Amplitudes of digastric E.M.G. were measured from the oscilloscope and the monitor connected to amplifier at different intensities of electronic anesthesia of 1 volt, 4 volt and 10 volt. The inhibited rate of the amplitudes of digastric E.M.G. were analysed statistically with paired t-test. The following results were obtained : 1. Non-acupuncture point stimulation with intensities of 1 volt, 4 volt and 10 volt showed the inhibitory effect on pain of 15%, 25% and 16% in teeth and 15%, 18% and 12% in gingiva respectively 2. In tooth, statistical significance was observed between control and each group. In gingiva, there was statistical significance between control and group 1, 2 except group 3 From these results, low frequency electrical stimulation of non-acupuncture point resulted in reducing of dental and gingival pain, it could be used as adjunct to other pain control methods.

• 산업경영시스템학회지
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• 제22권53호
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• pp.69-78
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• 1999

We developed an apparatus for odorous stimuli control to record olfactory evoked potentials from human scalp. The characteristics of the apparatus were as follows. 1. Translating the subjects respiration into electric signals with a sensor attached to the nose. The period and timing of odorous stimuli could be adjusted, so that stimuli could be synchronous with respiration. 2. The respirations translated into electric signals were made constant in amplitude by using an auto gain control circuit. 3. The interstimulus interval of odorous could be arbitrarily selected once every 1 to 9 respirations so that adaptation could be prevented. We obtained olfactory - evoked potentials (OEPs) to odorous stimuli using this apparatus from the site of Cz, whose positive peak latencies were approximately $180{\pm}23ms$. Such response were not recorded if oxygen stimuli were used instead of odorous or with click sounds produced by the switching electromagnetic valve.

• 대한약리학회지
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• 제20권2호
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• pp.23-34
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• 1984

실험적으로 명암주기 또는 암주기에 적응시킨 백서의 간뇌 homogenate에서 opiate receptor의 일중변동 유무를 검토하고, circadian rhythm에 영향을 미치는 것으로 알려진 수종 중추작용약물의 영향을 보고 저 7 group에서 4시간 간격으로 1일 6회 maximum $^3H-morphine$ binding을 측정하여 다음과 같은 성적을 얻었다. 1) L : D, 12 : 12에 적응시킨 대조군에서 maximum $^3H-morphine$ binding은 22시에 최고에 달하는 매우 유의한 일중변동을 보였고, 24시간 평균 $^3H-morphine$ binding치는 $0.45{\pm}0.03\;pmole/mg Protein이었다. 2) 지속적인 암적응을 시킨 D : D, 12 :12군에서 $^3H-morphine$ binding의 일중변동은 14시에 최하, 그리고 2시에 최고의 binding치를 보이는 만상성의 일주변동은 보였으며 대조군의 곡선과는 그 shape, Phase, 진폭, 최고 또는 최하 binding시기 및 24시간평균 opiate수용체의 수에 현저한 차이가 있었다. 3) 지속적인 암적응, reserpine, pargyline, imipramine, amphetamine 또는 chlorpromazine 처리는 opiate receptor의 일중변동을 변화시켰다. 4) 그러나 전 실험군에서 Kd치는 변동되지 않았다. 이상 실험성적으로 백서뇌내 opiate수용체의 일중변동은 수용체의 질적변동이 아닌 수적인변동에 의하고, 지속적인 암적응이나 circadian rhythm을 변동시키는 중추성 약물들이 opiate receptor의 일중변동을 변화시킬 수 있으며, 또한 동통을 포함하여 제종 진통제의 효과가 일중변동을 일으키는 것은 opiate receptor의 일중변동과 일정한 관계가 있을 것으로 추측하였다.