• 미생물과산업
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• 제20권1호
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• pp.50-52
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• 1994

Coccidioides immitis의 mycelial phase와 tissue phase에 있어서 미세구조를 다음과 같은 결론을 얻었다. 1. mycelial phase의 세포구조에서는 정상적인 균이 보유하고 있는 내용물질을 관찰할 수 있었으며 이는 다른 eucaryotic cell의 구조와 같았다. 2. tissue phase에서는 mycelial phase의 세포의 크기보다 비교적 크기가 컸으며 mycelial phase에서 보다 많은 종의 vacuole이 관찰되었다. 3. Tissue phase에서는 fibril form의 내연층을 볼 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.275-279
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• 1998

The influence of $WO_3$ (0.5-4.0mol%) on the microstructural and electrical properties of ZnO varistors was investigated. The major part of a tungsten segregated to the nodal point. SEM, EDAX, and XRD analysis revealed that three phase, such as W-rich phase, Bi-rich phase, and spinel phase, coexist at the nodal point. The average grain size increased in the range of 15.5-29.9pm with increasing $WO_3$ content. This may be probably attributed to liquid phase formed by $WO_3$, $WO_3$ acted as promotion additive of grain growth. As $WO_3$ content increase, the varistor voltage greatly decreased in the range 186.82-35.87V/mm due to the increase of grain growth. The barrier height decreased in the range 1.93-0.42eV with increasing $WO_3$content.

• Journal of the Optical Society of Korea
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• 제5권3호
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• pp.99-109
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• 2001

This paper presents a phase-only modulation scheme for a three-dimensional (3-D) image matching system to improve optical efficiency of the system. The 3-D image matching system is based on the two mask heterodyne scanning. A hologram of the 3-D reference object is first created and then the phase of the hologram is extracted. The phase of the hologram is represented as one mask with the other mask being a plane wave. The superposition of each beam modulated by the two masks generated a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the correlation of the phase-only hologram of the reference object and the complex hologram of the target object. Since a hologram contains 3-D information of an object as a form of fringe pattern, the correlation of holograms matches whole 3-D aspect of the objects. Computer simulations are performed with additive gaussian noise and without noise for the complex hologram modulation scheme and the phase-only hologram modulation scheme. The computer simulation results show that the phase-only hologram modulation scheme improves the optical efficiency. Thus the system with the phase-only hologram modulation scheme is more robust than the system with the complex hologram modulation scheme.

• 한국세라믹학회지
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• 제43권7호
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• pp.389-392
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• 2006

Electric field-induced phase transition from the tetragonal to rhombohedral phase was investigated for the <111> direction in tetragonal PZN-PT single crystals, which have spontaneous polarization along the <001> direction. From the strain and dielectric data, it was confirmed that the samples followed a tetragonal-orthorhombic-rhombohedral phase transition sequence with application of an electric field. This transition is different from the rhombohedral-tetragonal phase transition of <001> rhombohedral composition single crystals, in which a phase transition occurred without showing the intermediate orthorhombic phase.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.90-94
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• 2018

In this paper, we applied a three-level T-type inverter with the one more voltage level than two-level inverter. However, the three-level T-type inverter has a systematic problem with voltage unbalances. So neutral point control is essential. Therefore, the voltage unbalance problem of the three - phase inverter was confirmed to be controlled within 5V using the neutral point control algorithm in charge and discharge mode. In addition, total harmonic distortion was reduced in three phases (u phase, v phase, w phase) when neutral point control was performed in charging mode and also in three phases (u phase, v phase, w phase) in discharge mode. In this paper suggests a neutral point control algorithm to solve the voltage unbalance of a three-level T-type inverter, and shows the improvement of the performance of the proposed algorithm through experiment.

• 한국세라믹학회지
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• 제36권7호
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• pp.762-766
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• 1999

The crystal structure of A2+(Mg1/3Nb2/3)O3,(A2+=Sr2+ and Ca2+)ceramics was studied usig X-ray diffraction (XRD) and high resolution transmission electrion microscopy(HRTEM). Ba(Mg1/3Nb2/3)O3 (SMN) has the 1:2 ordered monoclinic structure which has the anti-phase tilt of octahedra. The type of tilting in SMN was considered to be a$^{\circ}$a$^{\circ}$c- or a­a­c$^{\circ}$ Ca(Mg1/3Nb2/3)O3 (CMN) also has the 1:2 ordered monoclinic structure which was distorted by the anti-phase tilt or in-phsae tilt of octahedra. A unit cell containing both the in-phase tilt axis and anti-phase tilt axis was not observed in the CMN. Therefore CMN has the mixed phase consisting of the 1:2 ordered monoclinic phase with anti-phase tilt of octahedra and the one with in -phase tilt of ocatahedra,. The anti-parallel shift of cation was also observed in the CMN.

• 한국광물학회지
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• 제15권3호
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• pp.161-169
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• 2002

고온-고압 상태에서 티탄철석 ($FeTiO_3$)의 상변이에 대한 연구가 있었으나, 그 결과는 서로 일치하지 않고 있다. 특히, 티탄철석상과 페롭스카이트상의 상변이 경계는 담금방법에 의해 결정된 것으로 신뢰도에 의문이 제기되고 있다. 이러한 문제를 해결하기 위해, 고온-고압 현장상태에서 라지 볼륨 기기와 방사광을 이용하여 19 GPa와 $700^{\circ}C$의 범위에서 X선 회절실험을 시행하였다. 이러한 실험결과, 페롭스카이트상은 상온에서 16 CPa 이상의 압력에서 안정하며, 15 CPa 근처에서 $LiNbO_3$상으로 변이한다. 또한 이 두 고온-고압상은 $500^{\circ}C$에서는 순간적인 상변이를 하고 있다. $LiNbO_3$상은 각각 13 CPa 및 300'E와 10.8 GPa 및 400'E에서 티탄철석상으로 상변이 한다. 따라서 본 실험결과는 $LiNbO_3$상은 고온-고압하에서 안정 영역을 확보하고 있으며, 페롭스카이트-티탄철석상경계는 이전에 발표된 결과와는 매우 다르다는 것을 지시해주고 있다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.397-401
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• 2004

In this paper, Inverter drives adopting 3-phase and 2-phase SRP-PWM (Separately Randomized Pulse Position PWM) with fixed switching frequency is proposed. In the proposed SRP-PWM scheme, each of 3 or 2 phase pulses Is located randomly in each switching interval. The experimental results show that the voltage / current harmonics and the switching noise harmonics are spread to a wide band area. Also, the performance of the 3-phase SRP-PWM and the 2-phase SRP-PWM are compared to each other. In result, the speed response is nearly similar to each other from the viewpoint of the v/f constant control.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.370-374
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• 2002

This paper describes the design and fabrication of distributed analog phase shifter circuit. The phase shifter consist of coplanar waveguide(CPW) lines that are periodically loaded with voltage tunable (Ba,Sr)TiO$_3$ thin film interdigital(IDT) capacitors deposited by the pulsed laser deposition(PLD) on (001) MgO single crystals. The phase velocity on these IDT loaded CPW lines is a function of applied bias voltage, thus resulting in analog phase shifting circuits. The measured differential phase shift is 48$^{\circ}$ and the insertion loss decreases from -5㏈ to -3㏈ with increasing bias voltage from 0 to 40 V at 100㎐.

• Current Optics and Photonics
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• 제2권4호
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• pp.332-339
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• 2018

A new multi-frequency fringe projection method is proposed to reduce the nonlinear phase error in 3-D shape measurements using an adaptive compensation method. The phase error of the traditional fringe projection technique originates from various sources such as lens distortion, the nonlinear imaging system and a nonsinusoidal fringe pattern that can be very difficult to model. Inherent possibility of phase error appearing hinders one from accurate 3-D reconstruction. In this work, an adaptive compensation algorithm is introduced to reduce adaptively the phase error resulting from the fringe projection profilometry. Three different frequencies are used for generating the gratings of projector and conveyed to the four-step phase-shifting procedure to measure the objects of very discontinuous surfaces. The 3-D shape results show that this proposed technique succeeds in reconstructing the 3-D shape of any type of objects.