Photophysical properties of highly efficient red-emitting CaTiO_3:Eu^3+ phosphors under near ultra-violet excitation

Myoung Gyu Ha,Jin Hwa Lee,배종성,김종필,홍경수,양호순 한국물리학회 2011 Current Applied Physics Vol.11 No.6

The photophysical properties of europium-doped calcium titanate for near ultra-violet excitation were studied in order to investigate whether it is applicable to white light-emitting diodes. CaTiO_3:Eu^3+phosphors were synthesized by using the solid-state reaction method. The structures and basic properties of the phosphors were characterized by using X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, and X-ray photoelectron spectrometer. The photophysical properties were examined by taking excitation and emission spectra. A strong red luminescence corresponding to 5^D_0 → 7^F_2 transition of Eu^3+ under near ultra-violet excitation was observed. It was found that CaTiO_3:Eu^3+ was a red-emitting phosphor and had higher efficiency for operation under near ultra-violet excitation.

Effects of Incorporated Alkali Metal Ions on the Chemical Bonding States and Optical Properties in Sr2SiO4:Sm3+ Phosphors

Myoung Gyu Ha,Kyoung-Rim Han,Ju Sung Kim,Yu Ri Bae,김종필,배종성,K. S. Hong,양호순 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.4

The effects of incorporated alkali metal ions on the chemical bonding states and optical propertiesin samarium-doped strontium orthosilicate phosphors are studied. Sr2−xMxSiO4:Sm3+ (M = Li, Na,and K) phosphors are synthesized by using tje solid-state reaction method to vary the incorporatedamount of the alkali metal ions. The structures, surface morphology, and chemical bonding states ofthe powders are analyzed. Optical properties for varying amounts of incorporated alkali metal ionsare examined by measuring absorption, excitation, and emission spectra. A red-orange emission dueto the transition of Sm3+ is observed in all samples, and powders with alkali metal ions incorporatedexhibit enhanced emission intensities by a factor of 1.24 to 2.16 compared with that of z pureSr2SiO4:Sm3+ powder with the same amount of Sm3+. We have shown that Sr2−xMxSiO4:Sm3+ceramics exhibit a red-orange emission with enhanced intensity for operation with near ultra-violetexcitation.

Decoupling Control of Induction Motors with Rotor Resistance Adaptation

GYU-SIK KIM,IN-JOONG HA,MYOUNG-SAM KO,HAN-KYOUNG BAE,JEONG-GYUN KIM,NO-CHAN KWAK 전력전자학회 1992 ICPE(ISPE)논문집 Vol.1992 No.4

In this paper, we attempt to control induction motors with maximum power efficiency as well as high dynamic performance by means of decoupling of motor speed (or motor torque) and rotor flux. For maximum power efficiency, the squared rotor flux is adjusted according to a minimum power search algorithm until the measured power input reaches the minimum. Since the motor speed is dynamically decoupled from the rotor flux, this can be done successfully without any degradation of motor speed responses. Our controller depends on rotor resistance but not on stator resistance. However, the performance of our control scheme is robust with respect to variations in rotor resistance because an identification algorithm for rotor resistance is employed.<br/>

Effect of early chemoradiotherapy in patients with limited stage small cell lung cancer

Ha, In-Bong,Jeong, Bae-Kwon,Jeong, Hojin,Choi, Hoon-Sik,Chai, Gyu-Young,Kang, Myoung-Hee,Kim, Hoon Gu,Lee, Gyeong-Won,Na, Jae-Beom,Kang, Ki-Mun The Korean Society for Radiation Oncology 2013 Radiation Oncology Journal Vol.31 No.4

Purpose: We evaluated the effect of early chemoradiotherapy on the treatment of patients with limited stage small cell lung cancer (LS-SCLC). Materials and Methods: Between January 2006 and December 2011, thirty-one patients with histologically proven LS-SCLC who were treated with two cycles of chemotherapy followed by concurrent chemoradiotherapy and consolidation chemotherapy were retrospectively analyzed. The chemotherapy regimen was composed of etoposide and cisplatin. Thoracic radiotherapy consisted of 50 to 60 Gy (median, 54 Gy) given in 5 to 6.5 weeks. Results: The follow-up period ranged from 5 to 53 months (median, 22 months). After chemoradiotherapy, 35.5% of the patients (11 patients) showed complete response, 61.3% (19 patients) showed partial response, 3.2% (one patient) showed progressive disease, resulting in an overall response rate of 96.8% (30 patients). The 1-, 2-, and 3-year overall survival (OS) rates were 66.5%, 41.0%, and 28.1%, respectively, with a median OS of 21.3 months. The 1-, 2-, and 3-year progression free survival (PFS) rates were 49.8%, 22.8%, and 13.7%, respectively, with median PFS of 12 months. The patterns of failure were: locoregional recurrences in 29.0% (nine patients), distant metastasis in 9.7% (three patients), and both locoregional and distant metastasis in 9.7% (three patients). Grade 3 or 4 toxicities of leukopenia, anemia, and thrombocytopenia were observed in 32.2%, 29.0%, and 25.8%, respectively. Grade 3 radiation esophagitis and radiation pneumonitis were shown in 12.9% and 6.4%, respectively. Conclusion: We conclude that early chemoradiotherapy for LS-SCLC provides feasible and acceptable local control and safety.

Meso-Scopic Analysis of Strain Path Change Effect on the Hardening Behavior of Dual-Phase Steel

Ha, Jinjin,Lee, Jinwoo,Kim, Ji Hoon,Barlat, Fré,dé,ric,Lee, Myoung-Gyu Wiley (John WileySons) 2014 STEEL RESEARCH INTERNATIONAL Vol.85 No.6

To study the anisotropic hardening behaviors of dual-phase steels under strain path changes, a meso-scale finite element analysis was considered with the representative volume elements. For the constitutive model, the Homogeneous yield function based on Anisotropic Hardening (HAH model) was used as a phenomenological constitutive equations to describe complex anisotropic material responses in an efficient way. For the martensite inclusions, three different configurations - elongated, large, and small spherical shapes - with two different volume fractions - 10 and 30% - were assumed. In order to represent strain path changes, two loading conditions were considered: tension-compression and tension-orthogonal tension. The simulation results for tension-compression test showed that the Bauschinger ratio increases as the volume fraction of martensite inclusion increases. For the tension-orthogonal tension test, the hard martensite attenuated the transient flow stress characteristics, which were observed in the single ferritic phase. The effect of hard phase inclusion was analytically explained using a simple one-dimensional analysis based on the elastic-linear plastic theory.

Investigation of plastic strain rate under strain path changes in dual-phase steel using microstructure-based modeling

Ha, Jinjin,Lee, Jinwoo,Kim, Ji Hoon,Lee, Myoung-Gyu,Barlat, Fré,dé,ric Elsevier 2017 International journal of plasticity Vol.93 No.-

<P><B>Abstract</B></P> <P>Micromechanical-based finite element simulations were carried out to investigate the transient plastic strain rate evolutions of ferrite and martensite dual-phase steel during strain path changes. A representative volume element (RVE) was generated through a three-dimensional (3D) reconstruction of microstructure images which were acquired from sequential polishing of a small material volume. The 10 × 10 × 10 μm<SUP>3</SUP> 3D RVEs consisted of martensite islands embedded in a ferrite base matrix. Each phase was assumed to exhibit distinct mechanical properties but the grain and phase boundary effects were ignored in this work. The effective mechanical properties for the constituent phases were assumed to be well defined by the von Mises or Hill 1948 yield criteria, the associated flow rule, and an empirical isotropic hardening equation based on chemical composition. This model was applied to investigate the transient behavior of the r-value (Lankford coefficient) in uniaxial tension when the loading direction changed. In addition to monotonic tension, compression-tension, and tension-orthogonal tension, sequences were considered. The simulation results captured well in a qualitative manner the experimental r-value evolutions in terms of a temporary transition and asymptotic limit. The evolutions of stress states in ferrite and martensite were analyzed to explain the r-value behavior that resulted from three factors: (1) r-value differences between ferrite and martensite, (2) martensite configuration-induced stress state in phases, and (3) stress partitioning and its evolution during non-proportional loading. Finally, an analytical relationship between the stress evolution in the constituent phases and the relevant r-value changes is suggested.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A 3D representative volume element is generated from real microstructure of DP780. </LI> <LI> The plastic strain dependent r-value evolution of DP780 is investigated. </LI> <LI> The stress partitioning in ferrite and martensite are analyzed. </LI> <LI> The analysis shows a strong correlation with r-value transition and loading history. </LI> <LI> An analytical model for the stress redistribution and r-value change is proposed. </LI> </UL> </P>

Speed and Efficiency Control of Induction Metors via Asymptotic Decoupling

Gyu-Sik Kim,In-Joong Ha,Myoung-Sam Ko,Dong-Il Kim,Jeom-Geun Kim 제어로봇시스템학회 1989 제어로봇시스템학회 국내학술대회 논문집 Vol.1989 No.10

Human erythropoietin induces lung failure and erythrocytosis in transgenic mice /

Kim, Myoung Ok,Kim, Sung Hyun,Shin, Mi Jung,Lee, Dong Beom,Kim, Tae Won,Kim, Kil Soo,Ha, Ji Hong,Lee, Sang Gyu,Park, Yong Bok,Kim, Sun Jung,Ryoo, Zae Young Korean Society for Molecular and Cellular Biology 2007 Molecules and cells Vol.23 No.1

單純化된 入出力 線型化技法에 依한 誘導電動機의 强靭한 速度 및 效率制御

金奎植(Gyu-Sik Kim),高明三(Myoung-Sam Ko),河仁重(In-Joong Ha),金點根(Jeom-Geun Kim) 대한전기학회 1990 전기학회논문지 Vol.39 No.10

아스파르트산 킬레이트 철분의 철분 결핍쥐에서의 생물학적 유용성

박명규(Myoung-Gyu Park),하태열(Tae-Yul Ha),신광순(Kwang-Soon Shin) 한국식품영양과학회 2011 한국식품영양과학회지 Vol.40 No.12

본 연구에서는 아스파르트산, 탄산칼슘 및 황산철을 반응 시켜 아스파르트산 킬레이트 철분(aspartic acid chelated iron, Asp-Fe)을 제조하고 Asp-Fe의 철분결핍 쥐(iron-deficient rat, ID)에서의 생물학적 유용성을 확인하였다. 시험군은 철분이 함유된 식이를 섭취한 정상군(NC), 철분 결핍 식이를 1개월간 투여하여 철분 결핍 상태를 유도한 쥐(ID)에 생리식염수를 공급한 결핍 대조군(ID+C), 철분 결핍 쥐에 햄철(heme-Fe) 투여군(ID+heme-Fe) 및 Asp-Fe 투여군 (ID+Asp-Fe)으로 나누어 실시하였다. 그 결과 식이섭취량, 장기무게, 체중증가 정도에서 각 군에 따른 차이가 없는 것으로 나타났다. 7일간 투여 후 혈액 중 철분의 함량을 측정한 결과 결핍쥐에 Asp-Fe 투여군(175.2 μg/dL)과 heme-Fe 투여군(140.8 μg/dL)은 결핍 대조군(96.1 μg/dL)보다 유의적인 수준으로 증가하였다. 총 철분 결합능(total iron binding capacity, TIBC)를 측정한 결과 Asp-Fe 투여군(735.4 μg/ dL)은 결핍 대조군(841.9 μg/dL)보다 유의적 수준으로 정상화되었다. 헤마토크리트(HCT) 수치를 측정한 결과에서 Asp- Fe 및 heme-Fe 모두 결핍 대조군보다 증가하는 경향은 보였지만 유의적인 차이는 없었다. 흡수율에서는 heme-Fe의 경우 21.3%인 반면에 Asp-Fe의 경우 50.2%로 약 2.3배 높은 것으로 나타났으며, 혈청에서의 철분농도 및 transferrin saturation( TS)는 heme-Fe 투여군 및 결핍 대조군에 비하여 Asp-Fe 투여군이 유의하게 높은 수준을 유지하였다. 이상의 결과로 미루어 볼 때 아미노산 킬레이트 철분은 heme-Fe과 유사한 수준의 생체 이용율을 가지고 있으며, 철분 결핍을 회복시키는데 매우 효과적인 보충제로서 이용될 수 있을 것으로 사료된다. Aspartic acid chelated iron (Asp-Fe) was synthesized by a new method using calcium carbonate, aspartic acid, and ferrous sulfate. This study was carried out to investigate the bioavailability of Asp-Fe in iron-deficient rats. We divided the rats into four experimental groups. The first was the normal diet control group, or NC. The second was the no treated control group of iron-deficient (ID) rats, or ID+C. The third was the heme-iron (heme-Fe) treated group of ID rats, ID+heme-Fe. And the fourth was the Asp-Fe treated group of ID rats, or ID+Asp-Fe. There were no differences among any of the experimental groups in diet consumption, change of body weight, or the weight of the livers, kidneys, or spleens. After 7 days of feeding, the iron content in the sera of the ID+Asp-Fe group (175.2 μg/dL) and the ID+heme-Fe group (140.8 μg/dL) were significantly higher than that of the ID-C group (96.1 μg/dL). The total iron binding capacity (TIBC) of the ID+Asp-Fe group (735.4 μg/dL) was significantly normalized compared to the ID+C group (841.9 μg/dL) or ID+heme-Fe group (824.6 μg/dL). The hematocrit level of the ID+Asp-Fe group was increased to normal levels, but there was no statistical difference among ID groups. The absorption ratio of heme-Fe was 21.3% and that of Asp-Fe was 50.2%, which indicates a 2.3 times higher ratio in comparison with heme iron. With the above results we found that Asp-Fe seems to be an efficient form of iron to supply iron deficient rats in order to cure them of anemia. Thus, these findings suggest that aspartic acid chelated iron has the potential to serve as a functional food related to iron metabolism.