• 전기학회논문지
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• 제57권4호
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• pp.603-609
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• 2008

Slotless linear brushless DC motor are widely used in precision machine applications because of their advantages such as low of detent force, negligible iron loss. But they have a disadvantage such as low thrust density, thrust ripple, and excessive use of permanent magnet materials. These lead to undesirable performance and high production cost. In this paper, we deal with the design and characteristics investigation of a air-core tubular linear brushless DC(TLBLDC) motor with air-core stator and permanent magnet mover. And to investigate the static and dynamic characteristics of air-core TLBLDC motor, the prototype machine is manufactured and analyzed by F.E.M. and Matlab simulink simulations. Especially, dynamic characteristics of air-core TLBLDC motor driven with 6 step inverter are simulated by F.E.M.coupling with external circuit and Matlab simulink program, and measured for the prototype motor. The simulation results are compared to the experimental results such as current waves, thrust and speed curve.

• 한국정밀공학회지
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• 제16권11호
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• pp.166-173
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• 1999

Al forged parts are many cases with rib-web section which is difficult to manufacture precisely. Therefore, process conditions must be optimized for precision forging of Al alloys. In this study, various process parameters such as die design, lubricant, ram speed, forging temperature have been investigated using the experiment, upper bound theory and F.E.M. simulation to develop the precision forging technology for rib-web shape component. When lubricant is applied to both material and die, shear friction factor is 0.1 which shows best effect of lubricant. It is specific corner radius of die that minimized forging load regarding process conditions, especially according to the ratio of the width of rib and web. In conclusion, optimum corner radius is 2~3mm when the width of rib and web is 3mm and 20mm respectively.

• 대한기계학회논문집A
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• 제37권11호
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• pp.1415-1421
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• 2013

최근에는 이러한 법공학 분야에 유한요소법 및 유한체적법을 이용한 다양한 시뮬레이션 기법을 활용하여 안전사고 및 재난사고에 대한 법적 책임문제를 해명하고 보다 정확한 원인분석을 통해 원인을 규명하고 있는 추세이다. 본 연구에서는 ADINA 구조해석을 이용하여 단경교 거더교 붕괴사고에 관한 좌굴 원인분석을 수행하였다. 본 연구에서 다루는 사고는 단경교 거더교 신축 중 상현 슬래브 구성을 위한 콘크리트 타설 중 교량이 붕괴된 사고로 원설계 공법에서 가설 공법이 변경되었고 상현 콘크리트 블록 및 격벽 콘크리트 등을 미시공한 상태에서 그 다음 단계인 상현 슬래브 콘크리트 타설을 진행함으로써 구조적 불안정을 가져와 거더가 좌굴이 발생하여 붕괴된 사고이다. 사고 재현 실험이 불가한 경우 F.E.M 을 이용한 구조안정성 비교 평가는 정확한 공학적 사고의 원인을 규명하는데 효과적인 방법이다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권12호
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• pp.5139-5145
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• 2016

There has been an increment in the number of studies focused on marine bioactive materials. Many peptides and other biomaterials with anticancer potential have been extracted from various marine animals. Artemia extracts have found uses in sun-light protection cosmetics and anti-aging products. However, contents of biochemical compounds in Artemia spp. and molecular mechanisms of have not been clearly studied in leukemic cells in vitro. In this work, we isolated and purified proteins of Artemia Urmiana. Six clear fractions (A-F) observed on DEAE-cellulose chromatography were assayed for effects on cell growth, differentiation and apoptosis using the human leukemic HL-60 cell line. Cell proliferation analysis by MTT and BrdU assays indicated that did not affect cells, growth. Cells treated with crude extract and fractions A, B and C, but not E and F (up to $100{\mu}g/mL$), exhibited increase of cell growth in a dose dependent manner. Stimulatory effects of fraction D were observed at concentrations of $10{\mu}g/mL$ and above. In nitro blue tetrazolium (NBT) reduction assays, treatment with $100{\mu}g/mL$ of fraction E or F for 96 hr increased the fraction of differentiated cells up to $14.8{\pm}3.56%$ and $16.5{\pm}2.08%$ respectively. Combination of those fractions with retinoic acid had significant synergistic effects on the differentiation of cells ($56.8{\pm}3.7%$ and $67.4{\pm}4.2%$, $p{\leq}0.01$). Annexin-V FITC staining for apoptosis and flow cytometric assays indicated induction of apoptosis by fractions E and F up to 23.8 and 31.8% of cells.

• 한국가축번식학회지
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• 제10권1호
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• pp.27-35
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• 1986

As a preliminary experiment to establish the process on the sexing of mouse embryos by chromosomal analysis, present studies were carried out with inbred (ICR, C57BL) and F1 hybrid [(ICR${\times}$C57BL) = F1 ${\times}$ ICR] mice to investigate the blastomere numbers and mitotic indices (M.I.) to the developmental stage of embryos recovered, the optimum periods of anti-mitotic agent administration, the successful rates of sexing and sex-ratio. The results obtained were summarized as follows: 1. The blastomere numbers (mean${\pm}$S.E.) of the morula and blastocyst were 18${\pm}$0.4 and 54${\pm}$0.7, respectively. 2. Whereas the M.I. of F1 hybrid (16${\pm}$0.2%) was higher than that fo inbred ICR (15${\pm}$0.1%) and C57BL (12${\pm}$0.6%) in the different strains, the morula (7${\pm}$0.6%) was higher than that of blastocyst (6${\pm}$0.4%) in the case of embryo stages. 3. Following to anti-mitotic agents treated, the M.I. of embryos cultured with Colcemid (17${\pm}$1.1%) was superior to that fo embryos cultured with Velban (12${\pm}$0.9%) and the Colcemid injection (7${\pm}$0.4%). 4. The successful rate of sexing in the blastocyst (38.7%; 124/320) was superior to the morula (35.9%; 52/145), and the F1 hybrid (48.1%) was higher than that of inbred ICR (42.4%) and C57 BL (28.2%). 5. In the successful rate of sexing to the methods of administration, the embryos cultured with Colcemid (46.0%) was superior to that of embryos cultured with Velban (39.0%) and the Colcemid injection (38.8%). 6. Of 98 embryos sexed after culture with Colcemid, 89(90.8%) were observed between 2 and 4 hrs. In the case of Velban treatment, 83.1% (74/89) was observed between 2$\frac{1}{2}$ and 4$\frac{1}{2}$ hrs. 7. Out of 761 prepared embryos it was possible to sex 311; 157 were male and 154 were female, i.e.a sex-ratio of 50% a, pp.oximately.

• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.155-160
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• 2009

Mast cells and basophils perform important functions as pivotal effector cells in IgE-mediated allergic reactions. KU812F cells, a human basophilic cell line isolated originally from chronic myelocytic leukemia, express a high affinity receptor of IgE, $Fc{\varepsilon}RI$. Kaempferol was extracted and isolated from a methanolic extract of flavonoid-rich Nelumbo nucifera stamens. In the present study, the inhibitory effects of kaempferol on $Fc{\varepsilon}RI$ expression in human basophilic KU812F cells was examined. Flow cytometric analysis revealed that $Fc{\varepsilon}RI$ expression on the cell surface was suppressed in a concentration-dependent manner when the cells were cultured with kaempferol. Moreover, RT-PCR analysis showed that the mRNA levels for $Fc{\varepsilon}RI$ ${\alpha}-\;and\;{\gamma}$-chains were reduced as the result of kaempferol treatment in a concentration-dependent manner. Kaempferol showed its suppressive effects on intracellular $Ca^{2+}$ concentration and histamine release from anti-$Fc{\varepsilon}RI$ ${\alpha}$-chain antibody-stimulated cells in a concentration-dependent manner. These observations indicate that kaempferol may exert antiallergic effect via down regulation of $Fc{\varepsilon}RI$ expression and degranulation.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 제2회 추계심포지움
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• pp.69-80
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• 1994

Although ureases play important roles in microbial nitrogen metabolism and in the pathogenesis of several human diseases, little is known of the mechanism of metallocenter biosynthesis in this Ni-Containing enzyme. Klebsiella aerogenes urease apo-protein was purified from cells grown in the absence of Ni. The purified apo-enzyme showed the same native molecular weight, charge, and subunit stoichiometry as the holo-enzyme. Chemical modification studies were consistent with histidinyl ligation of Ni. Apo-enzyme could not be activated by simple addition of Ni ions suggesting a requirement for a cellular factor. Deletion analysis showed that four accessory genes (ureD, ureE, ureF, and ureG) are necessary for the functional incorporation of the urease metallocenter. Whereas the $\Delta$ureD, $\Delta$ureF, and $\Delta$ureG mutants are inactive and their ureases lack Ni, the $\Delta$ureE mutants retain partial activity and their ureases possess corresponding lower levels of Ni. UreE and UreG peptides were identified by SDS-polyacrylamide gel comparisons of mutant and wild type cells and by N-terminal sequencing. UreD and UreF peptides, which are synthesized at ve교 low levels, were identified by using in vitro transcription/translation methods. Cotransformation of E. coli cells with the complementing plasmids confirmed that ureD and ureF gene products act in trans. UreE was purified and characterized. immunogold electron microscopic studies were used to localize UreE to the cytoplasm. Equilibrium dialysis studies of purified UreE with $^{63}$ NiC1$_2$ showed that it binds ～6 Ni in a specific manner with a $K_{d}$ of 9.6 $\pm$1.3 $\mu$M. Results from spectroscopic studies demonstrated that Ni ions are ligated by 5 histidinyl residues and a sixth N or O atom, consistent with participation of the polyhistidine tail at the carboxyl termini of the dimeric UreE in Ni binding. With these results and other known features of the urease-related gene products, a model for urease metallocenter biosynthesis is proposed in which UreE binds Ni and acts as a Ni donor to the urease apo-protein while UreG binds ATP and couples its Hydrolysis to the Ni incorporation process.ouples its Hydrolysis to the Ni incorporation process.s.

• Preventive Nutrition and Food Science
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• 제21권4호
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• pp.323-329
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• 2016

Achyranthes japonica Nakai (AJN) water extract has a variety of physiological properties, including anti-diabetic, anti-cancer, anti-inflammatory, anti-microbial, and anti-oxidative activities. In the present study, the inhibitory effects of AJN extract were investigated in high affinity immunoglobulin E receptor ($Fc{\varepsilon}RI$)-mediated KU812F cells activation. AJN extract showed suppressive effects on histamine release and intracellular calcium [$Ca^{2+}$]i elevation from anti$Fc{\varepsilon}RI$ antibody (CRA-1)-stimulated cells in a dose-dependent manner. Flow cytometric analysis showed that AJN extract treatment caused a dose-dependent decrease in the cell surface $Fc{\varepsilon}RI$ expression and the binding between the cell surface $Fc{\varepsilon}RI$ and the IgE antibody. Moreover, reverse transcription-polymerase chain reaction analysis showed that levels of the mRNA for the $Fc{\varepsilon}RI$ ${\alpha}$ chain was decreased by treatment with AJN extract. These results indicate that AJN extract may exert anti-allergic effects via the inhibition of calcium influx and histamine release, which occurs as a result from the downregulation of the binding of IgE antibody to cell surface $Fc{\varepsilon}RI$. This mechanism may occur through $Fc{\varepsilon}RI$ expression inhibition.

• 소성∙가공
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• 제11권2호
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• pp.171-178
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• 2002

The elastic deflections of the cold forging die influence the dimensional accuracy of forged parts. The die dimension is continuously changed during the loading, unloading, and ejecting stage. In this paper, we evaluated the elastic deflections of cold forging die during the loading, unloding and ejecting stage with experimental and FEM analysis. Uni-axial strain gages are used to measure elastic strain of die during each forging stage. Strain gages are attached un the upper surface of die. A commercial F.E.M. code, DEFORM$-2D^{TM}$ is used to predict the elastic strains of die, to be compared those by experiments. Two modelling approaches are used to define the reasonable analysis method. The first of the two modelling approaches is to regard the die as rigid body over forging cycle. And then, the die stress is analyzed by loading the die with pressure from the deformed part. The other is to regard the die as elastic body from forging cycle. The elastic strain of tool is calculated and the tool is elastically deformed at each strep. The calculated results under the elastic die assumption are well agreed wish experimental data using the strain gages.

• 전기전자학회논문지
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• 제13권3호
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• pp.55-61
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• 2009

본 논문에서는 정열계 해석을 위해 유한요소법(F.E.M)을 이용한 열전달 해석 기법에 대하여 다루고 있다. 특히, 열전달의 주요 쟁점인 혼합 경계조건을 띄는 대류 경계조건을 자계 문제와 비교하여 갤러킨법(Galerkin Method)으로 정식화하였다. 그리고 해의 신뢰성을 확보하기 위해 자계 해석을 통해 열원이 되는 손실을 구한 후, 반복적 알고리즘을 통해 에너지 평형 방정식을 만족하는 열전달 계수를 산정하여 열전달 문제를 고려하는 자계-열계 결합 해석을 하였다. 마지막으로, 측정치와 비교하여 제안된 방법의 효용성을 증명하였다.