• 한국분말재료학회지
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• 제30권5호
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• pp.402-408
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• 2023

This study focused on improving the phase stability and mechanical properties of yttria-stabilized zirconia (YSZ), commonly utilized in gas turbine engine thermal barrier coatings, by incorporating Gd₂O₃, Er₂O₃, and TiO₂. The addition of 3-valent rare earth elements to YSZ can reduce thermal conductivity and enhance phase stability while adding the 4-valent element TiO₂ can improve phase stability and mechanical properties. Sintered specimens were prepared with hot-press equipment. Phase analysis was conducted with X-ray diffraction (XRD), and mechanical properties were assessed with Vickers hardness equipment. The research results revealed that, except for Z10YGE10T, most compositions predominantly exhibited the t-phase. Increasing the content of 3-valent rare earth oxides resulted in a decrease in the monoclinic phase and an increase in the tetragonal phase. In addition, the t(400) angle decreased while the t(004) angle increased. The addition of 10 mol% of 3-valent rare-earth oxides discarded the t-phase and led to the complete development of the c-phase. Adding 10 mol% TiO₂ increased hardness than YSZ.

• 한국ITS학회 논문지
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• 제14권6호
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• pp.110-116
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• 2015

본 논문은 T 형태의 미엔더 선로를 적용한 브랜치 라인 커플러를 이용하여 고조파가 억압된 소형 저손실의 반사기 형태인 위상 변위기에 대해 제안을 한다. 위상 변위기의 소형 커플러는 $22.2{\times}14.9mm^2$의 크기를 갖고 있으며, 기존의 브랜치 커플러는 $32.6{\times}27.8mm^2$의 크기를 나타낸다. 본 논문에서 제안된 위상 변위기는 2.1 GHz의 중심 주파수에서 삽입손실 0.19~0.28 dB, 그리고 $137^{\circ}$의 최대 위상 변위를 보여주고 있다.

• 한국자기공명학회논문지
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• 제26권1호
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• pp.10-16
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• 2022

The phase transition temperatures of CsCoCl₃·2H₂O crystals are investigated via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Three endothermic peaks at temperatures of 370 K (=T_C1), 390 K (=T_C2), and 416 K (=T_C3) were observed for phase transitions from CsCoCl₃·2H₂O to CsCoCl₃·1.5H₂O, to CsCoCl₃·H₂O, and then to CsCoCl₃·0.5H₂O, respectively. In addition, the spin-lattice relaxation time T_1ρ in the rotating frame and T₁ in the laboratory frame as well as changes in chemical shifts for ¹H and ¹³³Cs near T_C1 were found to be temperature dependent. Our analyses results indicated that the changes of chemical shifts, T_1ρ, and T₁ are associated with structural phase transitions near temperature T_C1. The changes of chemical shifts, T_1ρ, and T₁ near T_C1 were associated with structural phase transitions, owing to the changes in the symmetry of the structure formed of H₂O and Cs⁺ ions. Consequently, the structural symmetry in CsCoCl₃·2H₂O crystals based on temperature is discussed by the environments of their H and Cs nuclei.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.40-45
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• 2019

The phase transition temperatures and thermodynamic properties of $(NH_4)_2MnCl_4{\cdot}2H_2O$ grown by the slow evaporation method were studied using differential scanning calorimetry and thermogravimetric analysis. A structural phase transition occurred at temperature $T_{C1}$ (=264 K), whereas the changes at $T_{C2}$ (=460 K) and $T_{C3}$ (=475 K) seemed to be chemical changes caused by thermal decomposition. In addition, the chemical shift and the spin-lattice relaxation time $T_{1{\rho}}$ were investigated using $^1H$ magic-angle spinning nuclear magnetic resonance (MAS NMR), in order to understand the role of $NH_4{^+}$ and $H_2O$. The rise in $T_{1{\rho}}$ with temperature was related to variations in the symmetry of the surrounding $H_2O$ and $NH_4{^+}$.

• 전력전자학회논문지
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• 제3권4호
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• pp.412-417
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• 1998

본 논문에서는 SRM의 2상 여자방식의 동작특성을 제시하였다. 제안한 방식은 스텝전동기의 2상 여자방식과 유사하게 동시에 2상을 여자하여 자기인덕턴스뿐만 아니라 상호인덕턴스에 의해서도 토오크를 발생시킨다. 상여자의 갑자스런 변화는 기계적인 변위를 만들고 이는 소음과 진동을 유발한다. 2상 여자방식에 의한 연속적인 상여자에 의해 갑작스런 상여자의 변화를 줄여 소음을 줄일 수 있었다. 기존의 여자방식과 동작원리와 특성을 비교함으로써 새로운 제어방식의 타당성을 입증하였다.

• 대한전기학회논문지
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• 제43권2호
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• pp.296-302
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• 1994

Polycrystalline CuInSeS12T thin were prepared by depositing Cu/In layer, which was sequentially sputtered varying the Cu/(Cu+In) mole ratio, on glass substrate and selenizing with selenium metal vapor in a nitrogen atmosphere. Compositional and structural, characterization was carried out by X-ray diffraction (XRD), wavelength-dispersive spectroscopy(WDS), and scanning electron microscope(SEM). Electrical characterization was carried out by the measurements of Hall effect, electrical resistivity. Large indium loss occurs in early stage of the selenization process. The selenized films which had mole ratios larger than 0.28 have chalcopyrite CuInSeS12T phase and these that had less mole ratios have sphalerite phase. The selenized films containing CuS1xTSe phase have Cu-rich CuInSeS12T phase and these that did not contain CuS1xTSe have In-rich CuInSeS12T phase. By optimizing the sputtering conditions,it is possible to fabricate CuInSeS12T thin films which have little secondary phases and an appropriate hole concentration (10S015T ~ 10S016TcmS0-3T) for solar cells.

• 한국미생물·생명공학회지
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• 제30권2호
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• pp.189-197
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• 2002

한국의 경기도 일대의 하천으로부터 광합성 박테리아 29균주를 분리하였다. 분리균주들은 Rhodopseudomonas blastica, Rhodocyclus gelationsus, Rhodocyclus tenuis, Rhodopseudomonas rutila로 동정되었다. 분리 동정된 광합성 박테리아들을 이용한 하수내 영양 염류 제거효율을 높이기 위한 고도처리 시스템을 연구하였다. 광합성 세균을 이용한 고도처리 시스템을 이용하여 합성폐수의 유기물 제거율 97∼99％, T-N 제거율 85∼97％, T-P 제거율 68∼99％을 얻을 수 있었다. 또한, 실폐수의 경우 유기물 제거율 96∼99％, T-N제거율 65∼95％, 및 T-P 제거율 63∼99％의 높은 폐수처리율을 얻을 수 있었다.

• Journal of the Optical Society of Korea
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• 제2권2호
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• pp.74-79
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• 1998

The use of a fiber Fabry-Perot interferometer (FFPI) as an optical current transducer is demonstrated. A conventional inductive pickup coil converts the time-varying current I(t) being measured to a voltage waveform V(t) applied across a piezeolectric strip to which the FFPI is bonded. The strip experiences a longitudinal expansion and contraction, resulting in an optical phase shift ${\phi}(t)$ in the fiber proportional to V(t). This phase shift is measured using a frequency-modulated semiconductor light source, photodiodes to monitor the reflected light from the FFPI and the laser power, and a digital signal processor. Calibration routines compute V(t) and I(t) from the measured phase shift at a l KHz rate. Response to 60 Hz ac over the design range 0-1300A rms is characterized Transient response of the FFPI transducer is also measured.

• 한국작물학회지
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• 제35권1호
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• pp.65-72
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• 1990

본 연구는 Japonica형 품종인 섬진벼와 통일형품종인 서광벼의 세포주기를 측정하고 온도의 하항에 따른 세포주기의 지연을 측정하여 품종간의 차이가 있는지를 조사하였다. 또한 세포주기를 phase별로 기간을 측정하고 온도의 변화에 따른 각 phase 기간변화로 조사하였다. 아울러 DNA, RNA 및 protein 합성량도 측정하여 세포주기와 어떠한 관련성이 있는지를 조사하였는데 얻어진 결과를 요약하면 다음과 같다. 1. 섬진벼와 서광벼의 세포주기는 3$0^{\circ}C$에서 6시간, 2$0^{\circ}C$에서 12시간으로 동일하였으나 15$^{\circ}C$에서는 섬진벼 18시간, 서광벼 20시간으로 나타난 것으로 보아 Japonica형 품종인 섬진벼가 통일형 품종인 서광벼에 비하여 냉해에 강한 것으로 나타났다. 2. 세포주기로부터 측정된 각 phase별 기간은 섬진벼가 2$0^{\circ}C$에서 $T_{G_1}$=2.0, $T_{s}$ =4.4, $T_{G_2}$=3.2 그리고 $T_{M}$=2.4 시간이었고, 3$0^{\circ}C$에서 $T_{G_1}$=1.8, $T_{s}$ =2.6, $T_{G_2}$=0.6 그리고 $T_{M}$=0.8 시간이었다. 서광벼에서는 2$0^{\circ}C$에서 $T_{G_1}$=3.0, $T_{s}$ =3.0, $T_{G_2}$=3.5 그리고 $T_{M}$=2.5시간이었고 3$0^{\circ}C$에서 $T_{G_1}$=1.5, $T_{s}$ =1.5, $T_{G_2}$=2.0 그리고 $T_{M}$=1.0시간이었다. 2$0^{\circ}C$에서 3$0^{\circ}C$로 배양온도가 상승함에 따라 섬진벼에서는 2$0^{\circ}C$에 비하여 3$0^{\circ}C$에서 $G_1$기는 길어졌고 $G_2$기와 M기는 짧아졌다. 그러나 서광벼에서는 각 phase의 상대적 기간이 거의 일정한 비율이었다. 3. DNA, RNA 및 protein 합성은 온도가 하항함에 따라 증가하는 경향이었다.

• 대한의용생체공학회:의공학회지
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• 제11권1호
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• pp.13-18
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• 1990

Frequency responses of ambulatory electrocardiogram systems were measured. Phase shift was assessed by our improved Wagner's method. The characteristics of the systems were found much worse than that of ordinary ECG equipment both in gain and phase responses. The decay of -3dB in amplitude observed in 0.2Hz and the lead of 45 dog in phase was observed in 0.6Hz. In order to investigate which of these 2 responses play major role in generating false S -T deviation, mathe- matical filters were Composed in a computer and actual ECGs were fed. The false S-T deviation were found to be caused mostly by enormous lead in phase, and then, the compensation circuit to diminish the lead in phase was inserted in the commercial systemes. The compensated systems showed no false deviation in S-T segment.