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      • KCI등재

        Robust voltage model flux estimator design with parallel vector compensator for sensorless drive of induction motor

        Gwon‑Jae Jo,Jong‑Woo Choi 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

        Flux estimator (FE) is critical for achieving high-performance sensorless drive of induction motors. A voltage model (VM) is an excellent candidate for a FE since it does not require speed information and has a simple structure. A VM using a closed-loop style has excellent sensorless drive capability over a wide speed range. However, it is limited by the uncertainties such as offset and parameter mismatch. This paper presents an improved a closed-loop style FE. To overcome the problems inherent in the conventional FE, a hybrid strategy for the changeover between control modes is applied. In the setting of the FE’s cutoff frequency (CF), the influences of the offset and parameter mismatch are analyzed. The phase distortion and acquisition of the back electromotive force are also analyzed. From this analysis, a vector compensation strategy for the flux linkage is applied. This strategy facilitates the CF setting, which improves the robustness against both the offset and parameter mismatch. Finally, the effectiveness of the proposed FE in a sensorless driven induction motor is verified using simulations and experiments under various conditions.

      • SCIESCOPUSKCI등재

        A Novel Method for the Identification of the Rotor Resistance and Mutual Inductance of Induction Motors Based on MRAC and RLS Estimation

        Jo, Gwon-Jae,Choi, Jong-Woo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

        In the rotor-flux oriented control used in induction motors, the electrical parameters of the motors should be identified. Among these parameters, the mutual inductance and rotor resistance should be accurately tuned for better operations. However, they are more difficult to identify than the stator resistance and stator transient inductance. The rotor resistance and mutual inductance can change in operations due to flux saturation and heat generation. When detuning of these parameters occurs, the performance of the control is degenerated. In this paper, a novel method for the concurrent identification of the two parameters is proposed based on recursive least square estimation and model reference adaptive control.

      • SCIESCOPUSKCI등재

        Robust voltage model flux estimator design with parallel vector compensator for sensorless drive of induction motors

        Jo, Gwon-Jae,Choi, Jong-Woo The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

        Flux estimator (FE) is critical for achieving high-performance sensorless drive of induction motors. A voltage model (VM) is an excellent candidate for a FE since it does not require speed information and has a simple structure. A VM using a closed-loop style has excellent sensorless drive capability over a wide speed range. However, it is limited by the uncertainties such as offset and parameter mismatch. This paper presents an improved a closed-loop style FE. To overcome the problems inherent in the conventional FE, a hybrid strategy for the changeover between control modes is applied. In the setting of the FE's cutoff frequency (CF), the influences of the offset and parameter mismatch are analyzed. The phase distortion and acquisition of the back electromotive force are also analyzed. From this analysis, a vector compensation strategy for the flux linkage is applied. This strategy facilitates the CF setting, which improves the robustness against both the offset and parameter mismatch. Finally, the effectiveness of the proposed FE in a sensorless driven induction motor is verified using simulations and experiments under various conditions.

      • SCIESCOPUSKCI등재

        A Novel Method for the Identification of the Rotor Resistance and Mutual Inductance of Induction Motors Based on MRAC and RLS Estimation

        Gwon-Jae Jo,Jong-Woo Choi 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

        In the rotor-flux oriented control used in induction motors, the electrical parameters of the motors should be identified. Among these parameters, the mutual inductance and rotor resistance should be accurately tuned for better operations. However, they are more difficult to identify than the stator resistance and stator transient inductance. The rotor resistance and mutual inductance can change in operations due to flux saturation and heat generation. When detuning of these parameters occurs, the performance of the control is degenerated. In this paper, a novel method for the concurrent identification of the two parameters is proposed based on recursive least square estimation and model reference adaptive control.

      • 다중선형회귀분석 기반 건설장비 이산화탄소 배출량 예측모델 개발

        권재민 ( Gwon Jae-min ),이재학 ( Lee Jae-hak ),조민도 ( Jo Min-do ),최영준 ( Choi Young-jun ),한승우 ( Han Seung-woo ) 한국건축시공학회 2019 한국건축시공학회 학술발표대회 논문집 Vol.19 No.2

        Environmental problems caused by GHG emitted by various industries are emerging around the world, and accordingly, relevant regulations are being applied by countries around the world. Korea is operating a carbon credit system that trades GHG in industry for money, which is expected to be applied to the construction industry. In addition, construction equipment using fossil fuels accounts for the largest portion of CO<sub>2</sub> emissions in the construction industry, and the importance of CO<sub>2</sub> reduction and prediction is increasing. However, there is a lack of data on the directly measured CO<sub>2</sub> emissions of construction equipment and there is no accurate methodology for measuring methods. Therefore, in this study, independent variables were derived based on the CO<sub>2</sub> emission data. In addition, multiple linear regression is performed for each independent variable to derive a predictive model of carbon dioxide emission by work type of construction equipment. It is expected that the construction process plan based on environmental factors in the construction industry can be established in the future.

      • 유도전동기의 폐루프 고피나스 자속 관측기를 이용한 전압 모델 자속 관측기의 구현

        조권재(Gwon-Jae Jo),최종우(Jong-Woo Choi) 대한전기학회 2015 대한전기학회 학술대회 논문집 Vol.2015 No.10

        Accurate estimation of rotor flux is very important to implement direct vector control of induction motors. In case that error of rotor parameters (such as rotor resistance and mutual inductance) of induction motors exists, voltage model among various flux observers shows superb performance because this observer is robust with respect to error of these parameters. However, it is difficult to realize the voltage model flux observer because of the effect of voltage offset which occurs from PWM inverter and by others. This paper proposes realization of the voltage model flux observer by using the conventional closed-loop Gopinath flux observer and analyzing of characteristic function of that.

      • KCI등재후보

        고분화간세포암: 삼중시기 나선식 CT 소견$^1$

        김승훈,임재훈,임효근,이원재,이순진,연재우,조재민,최동일,김승권,김하나,김갑철,Kim, Seung-Hun,Im, Jae-Hun,Im, Hyo-Geun,Lee, Won-Jae,Lee, Sun-Jin,Yeon, Jae-U,Jo, Jae-Min,Choe, Dong-Il,Kim, Seung-Gwon,Kim, Ha-Na,Kim, Gap-Cheol 대한영상의학회 2002 대한영상의학회지 Vol.47 No.3

        Purpose: To determine the imaging characteristics of well-differentiated hepatocellular carcinomas (HCCs), as seen at triple-phase helical CT. Materials and Methods: Thirty-eight well-differentiated HCCs in 29 patients who underwent surgical resection comprised our study population. Triple-phase helical CT images were obtained at 30 seconds, 70 seconds, and 3 minutes after contrast injection, and HCCs were divided into four groups according to their size: smaller than 1 cm (n=12), 1-2 cm (n=15), 2-4 cm (n=8), and larger than 4 cm (n=3), The enhancement patterns of HCCs at triple-phase helical CT were retrospectively analysed. Results: In the smaller than l cm group, the most common enhancement pattern at all three phases was iso-attenuation (n=8; 67%). In the 1-2 cm group, iso-attenuation (n=10; 67%) was most common during the arterial phase and slightly low attenuation during the portal and equilibrium phases while in the 2-4 cm group, high attenuation (n=6; 75%) was most common during the arterial and portal phases, and low attenuation during the equilibrium phase (n=6; 75%). Two (67%) of three cases in the larger than 4 cm group demonstrated low, including fatty, attenuation. The detection rate was 33% (4/12) in the smaller than 1 cm group, 87% (13/15) in the 1-2 cm group and 100% (11/11) in the 2-4 cm and larger than 4 cm groups. Conclusion: At triple-phase helical CT, the enhancement patterns of well-differentiated HCCs were diverse, and the detection rate of those larger than 1 cm was 92% (24/26). 목적: 고분화간세포암의 삼중시기 나선식 CT 소견을 알아 보고자 한다. 대상과 방법: 수술적 절제 후 병리조직학적으로 고분화간세포암으로 확진된 29 명 환자의 38병소를 대상으로 하였다. 삼중시기 나선식 CT 영상은 조영제 주입 후 30초, 70초 및 3분에 각각 얻었다. 간세포암을 크기에 따라 1 cm 미만(n=12), 1 cm 이상-2 cm 미만(n=15), 2 cm이상-4 cm 미만(n=8)그리고 4 cm 이상(n=3)의 4군으로 분류한 후, 삼중시기 나선식 CT에서 고분화간세포암의 조영증강 양상을 후향적으로 분석하였다. 결과: 가장 많은 조영증강 양상은 1 cm 미만 군에서는 세 시기 모두에서 등음영으로 보인 경우이고(8예, 67%),1-2 cm 군에서는 동맥기에는 등음영으로, 문맥기와 평형기에서 약간 낮은 음영으로 보이는 경우이고(10예, 67%),2-4 cm 군에서는 동맥기와 문맥기에서 고음영으로, 평형기에서 저음영으로 보이는 경우(6예, 75%)였다. 4 cm 이상 군 3예 중 2예(67%)에서 지방음영을 포함한 저음영으로 관찰되었다. 병변의 발견률은 1 cm 미만 군에서는 33%(4/12), 1-2 cm 군에서는 87%(13/15), 2-4 cm 군과 4 cm 이상 군에서는 100%(11/11)였다. 결론: 고분화간세포암의 삼중시기 나선식 CT의 조영증강 양상은 종괴의 크기에 따라 다양하게나타났다. 1 cm 이상 크기의 고분화간세포암은 92%(24/26)에서 발견할 수 있었다.

      • Improved near infrared-mediated hydrogel formation using diacrylated Pluronic F127-coated upconversion nanoparticles

        Gwon, Kihak,Jo, Eun-Jung,Sahu, Abhishek,Lee, Jae Young,Kim, Min-Gon,Tae, Giyoong Elsevier 2018 Materials science & engineering. C, Materials for Vol.90 No.-

        <P><B>Abstract</B></P> <P> <I>In situ</I> hydrogel synthesis based on photopolymerization has been recognized as a promising strategy that can be used for tissue augmentation. In this study, we developed an efficient <I>in situ</I> gelation method to prepare bulk hydrogels <I>via</I> near infrared (NIR)-mediated photopolymerization using acrylated polyethylene glycol and diacrylated Pluronic F127-coated upconversion nanoparticles (UCNPs). In our system, upon 980-nm laser irradiation, UCNPs transmit visible light, which triggers the activation of eosin Y to initiate polymerization. We found that the UCNPs coated with diacrylated Pluronic F127 can enhance the photopolymerization efficiency and thus enable the production of bulk hydrogel with requirement of a lower NIR light power compared to that required with the bare UCNPs. This photopolymerization approach will be beneficial to achieve <I>in situ</I> polymerization <I>in vivo</I> for various biomedical applications such as cell/drug delivery and construction of tissue augments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed an efficient bulk-sized <I>in situ</I> gelation method via NIR-mediated photopolymerization using UCNPs. </LI> <LI> UCNPs convert NIR irradiation into visible light to activate the initiator. </LI> <LI> Diacrylated Pluronic F127-coated UCNPs can enhance photopolymerization efficiency. </LI> <LI> This NIR-mediated <I>in situ</I>-forming hydrogels have the potential for biomedical applications. </LI> </UL> </P>

      • KCI등재

        분리된 Simiduia sp. SH-4가 생산하는 β-agarase의 특성조사

        김재덕(Jae-Deog Kim),이솔지(Sol-Ji Lee),조정권(Jeong-Gwon Jo),이동근(Dong-Geun Lee),이상현(Sang-Hyeon Lee) 한국생명과학회 2016 생명과학회지 Vol.26 No.4

        경상남도 남해군 미조면 연안으로부터 채취한 해수를 Marine agar 2216 배지에 도말하여 한천분해활성을 보이는 SH-4 균주를 분리하였다. 선택된 SH-4 균주는 16S rDNA 염기서열분석을 통해 Simiduia sp. SH-4로 명명하였다. Simiduia sp. SH-4 균주의 배양액으로부터 한천분해효소를 획득하여 한천분해활성을 측정하였다. 한천분해활성의 강도에 있어서 Simiduia sp. SH-4 유래 한천분해효소의 최고활성은 120.4 U/l로 나타났다. 한천분해활성은 30℃에서 최고치를 나타내었으며, 30℃에서의 활성을 100%로 하였을 때 20℃에서 30%, 40℃에서 75%의 상대활성 을 나타내었다. 최적 pH는 pH 6.0으로 pH 6.0의 활성을 100%로 하였을 때 pH 5.0과 pH 7.0에서 각각 91%와 59%의 상대활성을 나타내었다. TLC 분석 결과, Simiduia sp. SH-4는 neoagarotetraose 및 neoagarobiose 등의 neoagarooligosaccharides를 생성하는 것으로 보아 β-agarase를 생산하는 균주로 확인되었다. 따라서 Simiduia sp. SH-4균주와 이 균주가 생산하는 β-agarase는 식품, 화장품, 의약품 산업에서 기능성소재 생산자로서 유용하게 활용할 수 있을 것으로 기대된다. Agarases are classified into α-agarase and β-agarase that produce agarooligosaccharides and neoagarooligosaccharides, respectively. Neoagarooligosaccharides have whitening effect of skin, delay of starch degradation, and inhibition of bacterial growth etc. Hence, the object of this study was to isolate a novel agarase producing marine bacterium and characterization of its β-agarase. A novel agar-degrading bacterium was isolated from seashore of Namhae at Gyeongnamprovine, Korea and purely cultured with Marine agar 2216 media. The isolated bacterium was identified as Simiduia sp. SH-4 after 16S rRNA gene sequencing. The enzymatic sample was obtained from culture media of Simiduia sp. SH-4. Enzymatic activity was highly increased from 20(30% relative activity) to 30℃ (100%) and decreased from 30 to 40℃(75%) and so more. Relative activity was 100% at pH 6 while those were about 91% and 59% at pH 5.0 and 7.0, respectively, meaning the enzyme possesses narrow optimal pH range. Hence, the enzyme exhibited the maximal activity with 120.4 units/l at pH 6.0 and 30℃ in 20 mM Tris-HCl buffer. Thin layer chromatography (TLC) analysis showed that Simiduia sp. SH-4 produces β-agarase, which hydrolyze agarose to produce biofunctional neoagarooligosaccharides such as neoagarotetraose and neoagarobiose. Hence, broad applications would be possible using Simiduia sp. SH-4 and its enzyme in the food industry, cosmetics and medical fields.

      • Effect of Feeding Levels of Microbial Fermented Soya Protein on Hematological Status, Plasma Enzyme Activity and Immune Cell Populations in Weaned Pigs

        Young Gwon Kim,Prashant Shinde,Jae Yong Choi,Myung Sang Kwon,Byung Jo Chae 강원대학교 동물생명과학연구소(구 강원대학교 동물자원공동연구소) 2007 동물자원연구 Vol.18 No.-

        A total of 240 weaned pigs (Landrace ×Yorkshire × Duroc, 22±3 d of age, 5.16±0.90 kg initial body weight) were used to study the effect of feeding level of microbial fermented soya protein on their blood hematology, enzymes and immune cell populations. The microbial (Aspergillus oryzae + Bacillus subtilis) fermented soya protein (FSP) was used. Pigs were allotted to four dietary treatments, each comprising of 4 pens with 15 pigs. Basal diets consisted of 15% soya bean meal (Control diet); while for treatment diets SBM was replaced with 3, 6 and 9% FSP. The experimental diets were fed from 0 to 14 day after weaning and then a common commercial diet was fed from 15 to 35 day. Blood was collected on 14 and 35 day of experiment and analyzed for hematology, plasma aspartate transaminase (AST), plasma alanine transaminase (ALT) and immune cell populations. Increasing the level of FSP in the diet of pigs linearly decreased distribution of red blood cells (P<0.01), MPV (P<0.05), MO (P<0.05), EO (P<0.05) and BA (P<0.05) on d 14. Linear and quadratic decrease in the RBC (P<0.05), Hb (P<0.05), HCT (P<0.01), PLT (P<0.001) and EO (P<0.05) and linear increase in the MCHC (P<0.001), MPV (P<0.05), WBC (P<0.05) and NE (P<0.05) on d 35 was noted. Pigs fed with 6% FSP had lower (P<0.05) levels of AST and ALT on d 14, while the levels of ALT and AST on d 35 did not differ among the dietary treatments. Thus the results suggest that microbial fermented soya protein affected the hematological indices, immune cell populations and plasma enzymes in weaned pigs.

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