• 노동경제논집
• /
• 제41권3호
• /
• pp.1-59
• /
• 2018

근로장려세제는 저소득가구의 근로를 장려하고 실질소득을 지원하는 근로 연계형 소득지원제도이다. 따라서 노동시장의 밖에 있는 저소득가구를 얼마나 노동시장으로 유인했는지가 근로장려세제의 평가에 있어서 가장 핵심적인 질문이라고 할 수 있다. 본 논문은 2008년 시행 이후 여러 차례 세법개정에 따라 근로장려세제의 수급자격요건과 급여체계가 바뀌어 왔다는 점을 이용하여 근로장려세제의 노동공급 효과를 추정하고자 한다. 한국복지패널, 가계금융복지조사, 한국노동패널, 재정패널 자료를 이용하여 분석한 결과, 통계적으로 유의하면서 긍정적인 효과와 통계적으로 유의하지 않은 효과가 혼재되어 나타났다. 한편 2013년까지로 분석기간을 한정했을 때 긍정적 효과가 좀 더 크게 나타났는데, 사업소득자와 기초생활수급자의 수급자격을 인정한 이후에 효과성이 낮아진 것인가에 대해서는 후속연구가 필요하다.

• 한국지능시스템학회논문지
• /
• 제24권3호
• /
• pp.245-250
• /
• 2014

중독은 크게 매개체 자체가 중독성을 가진 매개성 중독과 매개체 자체가 중독성을 가진 것이 아니라 예민한 개인과 잠재된 어떤 행동과 결합하여 중독을 유발하는 유발성 중독으로 나눌 수 있다. 매개성 중독은 약물 중독, 알코올 중독과 주로 화학물질의 직접 적인 원인이 되어 중독현상을 일으킨다. 유발성 중독은 쇼핑 중독, 일 중독, 게임 중독, 인터넷 중독, TV중독, 도박 중독 등의 사이버 중독이 있다. 유발성 중독은 개인의 감수성의 문제로서 개인에 따른 편차가 존재한다. 본 논문에서는 전기 시스템의 R-L-C 직렬 회로와 기계 시스템의 Spring-Damper-Mass를 이용하여 등가적으로 동일한 2차원의 중독 모델을 제안한다. 제안한 중독 모델에 비선형 항을 추가하여 Duffing을 구성한 후 파라미터 변화에 의해 주기운동과 카오스 운동을 시계열과 위상공간으로 나타내었다. 또한 파라미터 중 통제계수의 변화에 의해 주기 운동은 중독 되기 전의 상태를 카오스 운동은 중독된 상태임을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제39권8호
• /
• pp.843-848
• /
• 2015

The objective of this study is to observe and optimize a typical ocean environment and reduce wave reflections in the wave flume. In order to generate ocean waves in the wave flume, a combination of a horizontal piston type wave generator and wave absorbers was installed in the channel. Two probes for measuring the wave heights, i.e., wave level gauges, were used to record the continuous variation of the wave surface, the phase difference, and the maximum (crest) and minimum (trough) points of the propagating waves. In order to optimize the shape and size of the propagating waves, several absorption methods were proposed. Apart from an active wave absorption method, we used methods that involved vertical porous plates, horizontal punching plates, and sloping-wall-type wave absorbers. To obtain the best propagating waves, a sloping-wall-type wave absorber was chosen and tested in terms of the constitutive filling materials and the location and shape of the plate. This study also focused on the theoretical prediction of the wave surface, separating them into the incident and reflective components. From the results, it is evident that the wave absorber comprising a hard filling material exhibits a better performance than the absorber comprising a soft material, i.e., the wave absorber can be a strong sink to control the energy of the incoming wave. In addition, larger wave absorbers correspond to lower reflectance because a larger volume can reduce the incoming wave energy. Therefore, at constant absorber conditions, the reflectance of the wave increases as the wave period increases. Finally, the reflectance of the wave was controlled to be less than 0.1 in this study so that the wave flume can be used to simulate an offshore environment.

• Journal of Mechanical Science and Technology
• /
• 제14권10호
• /
• pp.1131-1142
• /
• 2000

In an effort to illustrate the global variation of SMD (Sauter mean diameter, or $D_{32}$) and AMD (Arithmetic mean diameter, or $D_{10}$) at five axial downstream locations (i. e., at Z=30, 50, 80, 120, and 170 mm) under the different experimental conditions, the radial coordinate is normalized by the spray half-width. Experimental data to analyze the atomization characteristics concerning with an internal mixing type have been obtained using a PDPA(Phase Doppler Particle Analyzer). The air injection pressure was varied from 40 kPa to 120 kPa. In this study, counterflowing internal mixing nozzles manufactured at an angle of $15^{\circ}$with axi-symmetric tangential-drilled four holes have been considered. By comparing the results, it is clearly possible to discern the effects of increasing air pressure, suggesting that the disintegration process is enhanced and finer spray droplets can be obtained under higher air assist. The variations in $D_{32}$ are attributed to the characteristic feature of internal mixing nozzle in which the droplets are preferentially ejected downward with strong axial momentum, and dispersed with the larger droplets which are detected in the spray centerline at the near stations and smaller ones are generated due to further subsequent breakup by higher shear stresses at farther axial locations. The poor atomization around the centre close to the nozzle exit is attributed to the fact that the relatively lower rates of spherical particles are detected and these drops are not subject to instantaneous breakup in spite of the strong axial momentum. However, substantial increases in SMD from the central part toward the edge of the spray as they go farther downstream are mainly due to the fact that the relative velocity of droplet is too low to cause any subsequent disintegration.

• 한국재료학회지
• /
• 제21권9호
• /
• pp.509-514
• /
• 2011

In this study, optical emission spectroscopy was used to monitor the plasma produced during the RF magnetron sputtering of a $BaTiO_3$ target. The intensities of chemical species were measured by real time monitoring with various discharge parameters such as RF power, pressure, and discharge gas. The emission lines of elemental and ionized species from $BaTiO_3$ and Ti targets were analyzed to evaluate the film composition and the optimized growth conditions for $BaTiO_3$ films. The emissions from Ar(I, II), Ba(I, II) and Ti(I) were found during sputtering of the $BaTiO_3$ target in Ar atmosphere. With increasing RF power, all the line intensities increased because the electron density increased with increasing RF power. When the Ar pressure increased, the Ba(II) and Ti(I) line intensity increased, but the $Ar^+$ line intensity decreased with increasing pressure. This result shows that high pressure is of greater benefit for the ionization of Ba than for that of Ar. Oxygen depressed the intensity of the plasma more than Ar did. When the Ar/$O_2$ ratio decreased, the intensity of Ba decreased more sharply than that of Ti. This result indicates that the plasma composition strongly depends on the discharge gas atmosphere. When the oxygen increased, the Ba/Ti ratio and the thickness of the films decreased. The emission spectra showed consistent variation with applied power to the Ti target during co-sputtering of the $BaTiO_3$ and Ti targets. The co-sputtered films showed a Ba/Ti ratio of 1.05 to 0.73 with applied power to the Ti target. The films with different Ba/Ti ratios showed changes in grain size. Ti excess films annealed at $600^{\circ}C$ did not show the second phase such as $BaTi_2O_5$ and $TiO_2$.

• 전기학회논문지
• /
• 제57권7호
• /
• pp.1213-1217
• /
• 2008

Poling is an important process in fabricating PZT ceramic devices such as filters and resonators and activates piezoelectricity to sintered PZT ceramics. Tolerance of the operating frequency of these devices is tightly required in applications. And a factor to attribute the tolerance is the temperature dependence of the resonance frequency of PZT ceramics. In this paper the relationship of poling strength and temperature dependence of resonance frequency of PZT specimens was studied. The $Pb(Zr_{0.53}Ti_{0.47})O_3$ ceramics were fabricated and the poling strengths were chosen to be 0.5, 1.5, 2.5 and 3.5 [kV/mm]. The dielectric constant of the specimen poled in poling strength 0.5 [kV/mm] was less than that of unpoled specimen and the specimen poled in higher electric field had the higher dielectric constant. (002) peak in X-ray diffraction patterns of the specimens increased as poling strength increased. And the change of resonance frequency of the specimens according to the variation of temperature was measured. Resonance frequency of all specimens increased as the temperature increased. The specimen poled in higher electric field had the smaller positive temperature coefficient of resonance frequency. The effect that temperature coefficient of resonance frequency becomes smaller is obtained when Zr mole in PZT composition equation increase. Controlling the poling strength is believed to be a method to adjust the temperature stability of resonance frequency of the PZT ceramic devices.

• 전력전자학회논문지
• /
• 제15권5호
• /
• pp.411-416
• /
• 2010

본 논문에서는 변압기 기반 전압변동 발생기의 직렬변압기에 의한 전압강하 특성을 분석하였다. 전압변동 발생기의 회로구성 방식에는 여러 가지가 있으나 본 논문에서는 비교적 비용이 저렴하고 신뢰도가 높은 직렬변압기를 사용한 방식에 대해 다루고자 한다. 직렬변압기에 의한 전압강하는 변압기의 %Z와 부하용량 및 부하역률에 의해 결정된다. 직렬변압기의 설계가 잘못되면 전압강하가 심각하게 발생하여 제대로 된 성능을 확보할 수 없다. 본 논문에서는 10kVA급 전압변동 발생기에 대해 %Z가 4%인 직렬변압기를 사용한 경우 부하역률에 따른 전압강하를 분석하였으며 지상 부하일수록 전압강하가 증가하고 역률이 0.85 지상인 경우 전압강하가 4% 발생함을 시뮬레이션 및 실험을 통하여 확인하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권2호
• /
• pp.75-82
• /
• 1999

A compensation method of the motor parameters using zero sequence third harmonic voltage is presented for the speed sensorless vector control of the induction motor considering saturation of the flux. Generally, the air-gap flux of the saturated induction motor contains the space harmonic components rotating with the synchronous frequency of the motor. Because the EMF of the saturated induction motor contains the zero sequence harmonic voltages at the neutral point of the motor, those harmonic voltages can be used as a saturation index. In this work, the rotor flux observer is firstly designed for the speed sensorless vector control of induction motor. And a novel measurement method of the space harmonic voltage and a compensation method of th LPF(Low Pass Filter) are proposed. For compensating the non-linear variations of the magnetizing inductance depending on the saturation level of the motor, the dominant third harmonic voltage of the motor is used as a saturation function of the air-gap flux. And the variation of the stator resistance owing to the motor temperature can also be measured with the phase angle between the impressed voltage vector and the zero sequence voltage. The validity of the proposed parameter compensation scheme in the speed sensorless vector control using rotor flux observer is verified by the result of the simulations and the experiments.

• 한국전기전자재료학회논문지
• /
• 제18권1호
• /
• pp.30-37
• /
• 2005

The microwave dielectric properties and their related structural characteristics in solid solutions of (1-$\chi$) Ba($Mg_{1/3}$Nb$_{2/3}$) $O_3$-$\chi$La(Mg$_{2/3}$Nb$_{1}$3) $O_3$(BLMN) have been investigated by measuring the dielectric constant($\varepsilon$r), Q value and temperature coefficient of resonant frequency($\tau$f) and by observing the crystal structure using high resolution transmission electron microscopy (HRTEM). Microwave dielectric properties showed characteristic features for specific composition. Dielectric constant($\varepsilon$$_{r}$) showed maximum value at the composition which corresponds to the phase boundary between 1 : 2 ordered and 1 : 1 ordered structure. The increase in $\varepsilon$$_{r}$ may be caused by the rattling of ions by incorporating smaller ions and the disordered structure. The variation of temperature coefficient of resonant frequency($\tau$$_{f}$) was investigated in terms of oxygen octahedra tilting.dra tilting.

• 한국항공우주학회지
• /
• 제34권6호
• /
• pp.83-91
• /
• 2006

현대의 고성능 전투기는 공력성능 및 조종성능의 향상을 위하여 대부분 세로축 방향으로 항공기를 불안정하게 설계하는 정안정성 완화 개념을 채택하고 있다. 비행제어법칙의 설계 작업은 불안정하게 설계된 항공기에 안정성을 부여하고, 주어진 비행임무에 대하여 만족스런 조종성능을 발휘할 수 있도록 비행성능을 조작하는 일련의 과정이다. 세로축 무게중심은 무장형상, 연료상태 및 착륙장치의 위치에 영향을 받으며 항공기 안정성에 많은 영향을 미친다. 따라서 무게중심의 이동은 세로축 안정도 여유에 영향을 미친다. 본 논문에서는 운용 시에 발생 가능한 최대 후방 무게중심에 대해 항공기 안정성을 해석하였고, 비행시험을 통해 최종적으로 검증하였다. 선형해석 항목은 세로축 단주기 모드 특성 및 안정도 여유에 관하여 행하였으며, 비선형 해석 항목은 단주기 모드를 해석하기 위해 세로축 가진 입력에 대한 항공기 응답특성을 분석하였다. 또한, 최대 후방 무게중심에서 수행된 고받음각 비행시험 자료를 제시함으로써 T-50 고등훈련기의 비행 안정성을 제시하였다.