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A New Vector Control Scheme of Brushless DC Motor
Sung-Jun Park,Young-Bae Choo,Han-Woong Park,Jin-Ghil Park,Cheul-U Kim 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
In this paper, the new vector control scheme of BLDCM producing loss-minimized ripple-free torque based on the d-q-0 reference frame is presented including 3 phase unbalanced condition The optimized phase current wave-forms that are obtained by the proposed method can be a reference values and the motor winding currents are forced to track it by delta modulation technique. As a results, it can be shown that the proposed work provides a simple and clear way to obtain an optimal motor excitation current.
Bae, Woong Jin,Zhu, Guan Qun,Choi, Sae Woong,Jeong, Hyun Cheol,Bashraheel, Fahad,Kim, Kang Sup,Kim, Su Jin,Cho, Hyuk Jin,Ha, U Syn,Hong, Sung Hoo,Lee, Ji Youl,Oh, Hyun-A,Koo, Hye Cheong,Kim, Do Ram,Hw Hindawi 2017 Oxidative medicine and cellular longevity Vol.2017 No.-
<P>The Korean herbal formulation Ojayeonjonghwan is used for improving late-onset hypogonadism (LOH) symptoms such as erectile dysfunction (ED). A previous research suggested that a modified Ojayeonjonghwan (KH-204) could be used as an alternative to the treatment for ED. The pharmacological effects were examined in different conditions, including in vitro and in vivo. We measured the survival rate of TM3 Leydig cells under the oxidative stress condition. The s.c. injection of leuprorelin was used to induce androgen deprivation. We measured serum testosterone levels, oxidative stress, and apoptosis. The results of the treatment by KH-204 (1) preserved TM3 cells from oxidative stress by improving the expression of nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1); (2) lowered the expression of transforming growth factor-beta (TGF-<I>β</I>) 1/SMAD; (3) increased the average of serum testosterone in androgen-deprived male rats; (4) kept the activation of spermatogenesis; (5) upgraded the contents of 8-hydroxy-20-deoxyguanosine (8-OHdG) and degraded the contents of superoxide dismutase (SOD); and (6) reduced apoptosis. We studied that KH-204 improved testicular dysfunction in LOH. It is likely, at least in part, to degrade oxidative stress through the Nrf2/HO-1 pathway. These findings may offer credible evidences for the use of new alternative therapies to treat LOH.</P>
Bae, Woong Jin,Park, Hyo Jung,Koo, Hye Cheong,Kim, Do Ram,Ha, U-Syn,Kim, Kang Sup,Kim, Su Jin,Cho, Hyuk Jin,Hong, Sung Hoo,Lee, Ji Youl,Hwang, Sung Yeoun,Kim, Sae Woong Hindawi Publishing Corporation 2016 Evidence-based Complementary and Alternative Medic Vol.2016 No.-
<P>We evaluated the effects of Seoritae extract (SE) on mild to moderate lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH). Seventy-six subjects with mild to moderate LUTS suggestive of BPH were prospectively recruited from the urology outpatient clinic and assigned to either SE (4200 mg or 6 tablets 3 times a day) or matching placebo. The primary outcome variable, the International Prostatic Symptom Score (IPSS), was evaluated at baseline and at 4 and 12 weeks. Postvoid residual volume (PVR), maximum urine flow rate (<I>Q</I><SUB>max</SUB>), and prostate-specific antigen (PSA) levels were evaluated. IPSSs decreased significantly from baseline to 12 weeks within the SE group. Significant improvements in IPSS voiding scores at 4 and 12 weeks were also observed in the SE group compared to the placebo group. IPSS storage and quality of life scores were also significantly decreased at 12 weeks in the SE group. There was no change in <I>Q</I><SUB>max</SUB> or PVR in both groups after 12 weeks. Administration of SE for 12 weeks led to significant improvements in LUTS, and it can be concerned as a reasonable and safe alternative for men with mild to moderate LUTS.</P>
( Sang-u Bae ),( Young-rok Seo ),( Min Lee ),( Sang-min Lee ),( Birm-june Kim ) 한국목재공학회 2019 한국목재공학회 학술발표논문집 Vol.2019 No.1
3D printing technology has the advantages of being able to rapidly fabricate objects that require complexity and high resolution through manipulation of computer aided design(CAD) models and softwares. Particularly, it is a very efficient technique in terms of material consumption because it is manufactured by stacking materials instead of conventional cutting or assembling techniques. However, since the materials used in 3D printing are very limited, the necessity of developing various new materials is highly required. In this study, we investigated that the effect of wood content on the mechanical and morphological properties of 3D printed parts. Based on poly lactic acid(PLA) matrix, the loading level of wood flour was varied from 0% to 40% by weight. In addition, 5 phr of ethylene propylene diene monomer(EPDM), one kind of elastomer, was added to each formulation to overcome the inherent brittleness of PLA and to improve the usability of filament and compatibility with wood flour. For characterizations, fused deposition modelling(FDM) 3D printing was performed after filament preparation. Tensile, flexural properties, and impact strength of the specimens were tested and then scanning electron microscope(SEM) analysis was performed to observe the layer formation behavior and the microstructure of the fractured surfaces. The configuration of the layer line was roughened and irregular as the wood flour was added. As the content of wood flour increased, the flexural properties tended to degrade, but the tensile properties and the impact strength showed somewhat different features.
( Sang-u Bae ),( Young-rok Seo ),( Jae-gyoung Gwon ),( Sun-young Lee ),( Birm-june Kim ) 한국목재공학회 2019 한국목재공학회 학술발표논문집 Vol.2019 No.1
The effects of accelerated weathering on the visual appearance, chemical changes, and water absorption properties of waste WPC/virgin WPC blends-based composites were investigated. The visual appearance of the weathered surface of composites was observed through colorimeter and visual photos. Also, FT-IR was employed for analysis the changes in chemical composition. The trends of water absorption and thickness swelling of the composite specimens were measured as well. This study showed that as the UV exposure time for weathering was getting longer, the color fading of the surface, carbonyl concentrations, water uptake, and thickness swelling rate were increased in all specimens. In particular, the higher the virgin WPC content, the higher the color change, carbonyl concentration, and absorption rate. Moreover, in this study, we investigated how the degradation behaviour of virgin WPC and waste WPC correlate with chemical and color changes by accelerated weathering. Besides, during the weathering test, wood lignin was photo-oxidized and deteriorated, resulting in a considerable color fading in the WPC surface.
< 전시-P-45 > Accelerated Weathering of Virgin WPC/Waste WPC: Mechanical and Morphological Properties
( Sang-u Bae ),( Young-rok Seo ),( Jae-gyoung Gwon ),( Sun-young Lee ),( Birm-june Kim ) 한국목재공학회 2019 한국목재공학회 학술발표논문집 Vol.2019 No.1
Wood-plastic composites (WPCs) have attracted much attention in recent decades due to their competitive cost, great processability and excellent physical performance. Also, some of their main applications are represented by outdoor decking and furnishing. Since they are mainly applied to outdoor places, it is very important to evaluate the degradation behavior of WPCs under UV irradiation and moisture exposure, which are the major natural weathering factors. The chief aim of this research is to recycle waste-WPC(W-WPC) collected after use. However, such a W-WPC is inevitably deteriorated properties. In order to overcome these problems, virgin-WPC(V-WPC) was prepared with the same recipe as that of the original WPC. Five different blends were designed with different proportions of W-WPC and V-WPC. Each of the blends was prepared using extrusion and injection moulding, and then it was subjected to analyze various characterizations. The evaluation of weathering behavior by accelerated artificial weathering was carried out according to ASTM D2565 and total 1000 hours of exposure time was applied to test specimens using the Weather-O-Meter(WOM) equipment. Tensile, flexural properties, and impact strength of the specimens were tested at each 250, 500, and 1000 hours after accelerated weathering. The morphology of the weathered surface was observed by scanning electron microscope(SEM). From this study, a certain corelation between mechanical and morphological properties that occurred during accelerated weathering of W-WPC/V-WPC blends were established.
( Sang-u Bae ),( Young-rok Seo ),( Won-ki Moon ),( Seul-ye Ryu ),( Jeong-yeon Choi ),( Ye-jin Park ),( Ji-youn Song ),( Jin-young Bae ),( Birm-june Kim ) 한국목재공학회 2018 한국목재공학회 학술발표논문집 Vol.2018 No.1
CNC(cellulose nanocrystal) is a renewable and biodegradable reinforcing filler that gives impressive mechanical properties to filled polymer composites. However, further studies are required for its application because of its low dispersibility in nonpolar polymer matrix, which is one major drawback for the application of CNC as a high value-added additive, and its strong tendency for self-agglomeration by internal hydrogen bonding. To overcome these shortcomings, the surface of CNC was modified with silane coupling agent(aminoethyl-aminopropyl-trimethoxysilane, AEAPTMS) and some characterizations were examined. AEAPTMS is a kind of silane coupling agent and is known as an additive that effectively improves the functionality and compatibility with the polymer matrix. By just silylating the CNC surface with silane aquatic solutions, the CNC surface can be modified in a more direct, convenient and environmentally-friendly manner without using any hazardous solvents. The surface modified CNCs were analyzed using various characterization instruments (field emission scanning electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis, etc.) in comparison with MFC(microfibrillated cellulose) and pristine CNC materials. This study is expected to improve the applicability and value-added of CNC as a reinforcing filler for various polymer composites.
Bae, Woong Jin,Ha, U. Syn,Choi, Jin Bong,Kim, Kang Sup,Kim, Su Jin,Cho, Hyuk Jin,Hong, Sung Hoo,Lee, Ji Youl,Wang, Zhiping,Hwang, Sung Yeoun,Kim, Sae Woong Hindawi Publishing Corporation 2016 Oxidative medicine and cellular longevity Vol.2016 No.-
<P>Higher testicular temperature results in altered spermatogenesis due to heat-related oxidative stress. We examined the effects of decursin extracted from<I> Angelica gigas</I> Nakai on antioxidant activity<I> in vitro</I> and in a cryptorchidism-induced infertility rat model. TM3 Leydig cell viability was measured based on oxidative stress according to treatment. Either distilled water or AG 400 mg/kg of<I> A. gigas</I> extract was administered orally for 4 weeks after unilateral cryptorchidism was induced. After 1, 2, and 4 weeks, six rats from the control group and six rats from treatment group were sacrificed. Testicular weight, semen quality, antioxidant activities, nuclear factor erythroid 2-related factor 2 (Nrf2) protein, and mRNA expression of Nrf2-regulated genes were analyzed. Treatment with<I> A. gigas</I> extract (1) protected TM3 cells against oxidative stress in a dose-dependent manner, (2) improved the mean weight of the cryptorchid testis, (3) maintained sperm counts, motility, and spermatogenic cell density, (4) decreased levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and increased levels of superoxide dismutase (SOD), (5) significantly increased Nrf2 and heme oxygenase-1 (HO-1), and (6) significantly decreased apoptosis. This study suggests that decursin extracted from<I> A. gigas</I> is a supplemental agent that can reduce oxidative stress by Nrf2-mediated upregulation of HO-1 in rat experimentally induced unilateral cryptorchidism and may improve cryptorchidism-induced infertility.</P>