• 한국조명전기설비학회지:조명전기설비
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• 제7권2호
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• pp.31-35
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• 1993

본 논문은 t은과 10[torr]의 희유기체의 혼합기체 중에서 심하게 변조된 저압기체방전의 양광주의 반경방향 압자분포를 이론적으로 연구하였다. 전류는 깊이 50[%[로 정현파로 변조되었다. 계산결과 여기 원자의 반경방향 분포는 0차 Bessel 함수 $J_0(2.4r/R)$와 다르고 분포의 반전이 나타나는 주파수 대역도 있었다. 연립미분방정식을 풀기 위하여 FDM과 2계 Runge-Kutta method의 혼합법을 사용하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1339-1342
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• 2005

The development of an accurate and energy saving pneumatic regulator that may be applied to a variety of practical pressure control applications is described in this paper. A novel modified pulse width modulation(MPWM) valve pulsing algorithm allows the pneumatic regulator to become energy saving system. A comparison between the system response of conventional PWM algorithm and that of the modified PWM(MPWM) algorithm shows that the control performance is almost the same, but energy saving is greatly improved by adopting this new MPWM algorithm. The effectiveness of the proposed control algorithm is demonstrated through experiments with various reference trajectories.

• 한국유체기계학회 논문집
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• 제14권2호
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• pp.41-46
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• 2011

This study investigated the changes in performance and operating characteristics of an F-class gas turbine according to the change of working fluid from air to carbon dioxide. The revised gas turbine is the topping cycle of the semi-closed oxy-fuel combustion combined cycle. With the same turbine inlet temperature, the $CO_2$ gas turbine is expected to produce about 85% more power. The main contributor is the greater compressor mass flow and the added oxygen flow for the combustion. Compressor pressure ratio increases about 50%. However, the gas turbine efficiency reduces about 10 %. Modulation of inlet guide vane to reduce the compressor inlet mass flow, the major purpose of which is to reduce the compressor inlet Mach number, was also performed.

• 대기
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• 제25권3호
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• pp.559-568
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• 2015

As is evident from its definition, Southern Oscillation Index variability conformed to a combination of the variations of Darwin and Tahiti pressure. Over the El-$Ni{\tilde{n}}o$ Southern Oscillation spectra, the Darwin pressure shared variations associated with the SSN tendency while the Tahiti had a connection with the stratospheric quasi-biennial oscillation modulating annual cycle. The power peak near the 3.5-year period comprised the third harmonic of the sun and the second of the modulated annual cycle. The derived harmonics came from both sources, so the initiation of El-$Ni{\tilde{n}}o$ could be predicted more successfully when including the effects of the sun and QBO.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.147-150
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• 2002

HPSL(High Pressure Sodium lamp)have attracted much attention in recent years, because they offer high luminous efficiency and very long life. Recently, AC-DC converters have been widely as power factor improvement circuits in the power conversion equipment An application of the ZVT-PWM(Zero Voltage Transition Pulse Width Modulation) boost converter, which has great advantage on miniaturization and high power density, to the power factor improvement circuit of the HPSL inverter are described to identify the power factor correction characteristics of the inverter. In this paper the series-parallel resonant inverter(electronic ballast) for driving a HPS lamp is discussed. Finally, a power factor corrector is cascaded in front of the electronic ballast. Consequently, a high power factor above 0.99 and low THD on the line current can be achieved.

• 한국자동차공학회논문집
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• 제8권1호
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• pp.23-31
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• 2000

Knock and misfire, kinds of abnormal combustion, are highly undesirable effect on the internal combustion engine. So, it is important to detect these avnormal combuition and control the ignition timing etc. to avoid these mal-effect factors in real engine system. In this study, the system which detects the knock and the misfire using by spark plug is presented. This system is based on the effect of modulation breakdown voltage(BDV) between the spark gaps. The voltage drop between spark plug electrodes, when an electrical breakdown is initiated, depends on the temperature and pressure in combustion chamber. So, we can detect knock and misfire that produce changes in gas temperature and pressure (consequently, its density) using by BDV signal change which carries information about the character of combustion.

• Journal of Ginseng Research
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• 제42권3호
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• pp.264-269
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• 2018

Panax ginseng, also called Asian or Korean ginseng, has long been traditionally used in Korea and China to treat various diseases. The major active ingredients of P. ginseng are ginsenosides, which have been shown to have a variety of therapeutic effects, including antioxidation, anti-inflammatory, vasorelaxation, antiallergic, antidiabetic, and anticancer. To date, approximately 40 ginsenoside components have been reported. Current research is concentrating on using a single ginseng compound, one of the ginsenosides, instead of the total ginseng compounds, to determine the mechanisms of ginseng and ginsenosides. Recent in vitro and in vivo results show that ginseng has beneficial effects on cardiac and vascular diseases through efficacy, including antioxidation, control of vasomotor function, modulation of ion channels and signal transduction, improvement of lipid profiles, adjustment of blood pressure, improvement in cardiac function, and reduction in platelet adhesion. This review aims to provide valuable information on the traditional uses of ginseng and ginsenosides, their therapeutic applications in animal models and humans, and the pharmacological action of ginseng and ginsenosides.

• 한국정밀공학회지
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• 제11권6호
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• pp.127-135
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• 1994

This paper is concerned about a high speed electromagnet of Pressure control solenoid valve. Solenoid valve is controlled by means of Pulse width modulation. The magnetostatic field problem on a solenoid is numerically solved by the 2-D axisymmetric finite element method. And permeance method is adopted for analysing the static and dynamic property of solenoid part theoretically. In addition, in this study, experiments on solenoid part were performed in order to measure the magnetic force and plunger displacement. The numerical results coincided with the experimental results. As a result, the magnetic force has the linear relation with displacement of plunger and the primary factors on the performance of PWM type high speed electromagnet are coil resistance, plunger mass, and the length of air gap between plunger and core.

• Human Ecology Research
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• 제61권3호
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• pp.429-443
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• 2023

The purpose of this study was to investigate whether internal control, autonomous motivation of middle school students, and perceived parental pressure on academic performance affect academic procrastination, while verifying the moderating roles of autonomous motivation and parental pressure on academic performance. The participants were a total of 371 middle school students. Academic procrastination, internal control, autonomous motivation, and parental pressure on academic performance were measured using the Procrastination Inventory (Aitken, 1982) revised by Jeon and Park (2014), the Internal-External Control Scale (Ko, 2014), the Academic Self-Regulation Questionnaire (Ryan & Connell, 1989) revised by Kim (2002), and the Scale of Kang (2003), respectively. The collected data was analyzed using SPSS 26.0 and a Process Macro Model 2 (multiple additional modulation effect). The results of the study are summarized as follows. First, middle school students' internal control, autonomous motivation, and perceived parental pressure on academic performance directly affected the students's academic procrastination. Second, the moderating role of parental pressure on academic performance was significant. On the other hand, the moderating role of autonomous motivation was not significant. In conclusion, the results of this study suggest that in order to reduce and prevent academic procrastination it is important to improve internal control by helping middle school students become confident enough to believe that they have the ability to change their behavior and achieve their aims. At the same time, parents need to be interested in the process rather than only the academic performance of their children and support their autonomy.

• 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.