• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2000년도 추계학술발표회 초록집
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• pp.50-51
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• 2000

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권1호
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• pp.40-47
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• 2002

This paper describes a re-adhesion control method for the Korean High-Speed Train (KHST) with parallel induction motor drive. To keep a traction efficiency and to improve vehicle maintenance, the adhesion characteristics between wheel and rail are analyzed. Also the re-adhesion controller is designed as the subsystem of induction motor vector control. In order to verify performance of the proposed control techniques, the simulation is executed by train model and a downscaled re-adhesion control simulator is utilized. Both simulation and running test results show that good re-adhesion characteristics are obtained.

• 한국농공학회논문집
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• 제46권1호
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• pp.41-51
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• 2004

FRP re-bar in concrete structures could be used as a substitute of steel re-bars for that cases in which aggressive environment produce high steel corrosion, or lightweight is an important design factor, or transportation cost increase significantly with the weight of the materials. But FRP fibers have only linearly elastic stress-strain behavior; whereas, steel re-bar has linear elastic behavior up to the yield point followed by large plastic deformation and strain hardening. Thus, the current FRP re-bars are not suitable concrete reinforcement where a large amount of plastic deformation prior to collapse is required. The main objectives of this study in to evaluate the tensile behavior and the fracture mode of hybrid FRP re-bar. Fracture mode of hybrid FRP re-bar is unique. The only feature common to the failure of the hybrid FRP re-bars and the composite is the random fiber fracture and multilevel fracture of sleeve fibers, and the resin laceration behavior in both the sleeve and the core areas. Also, the result of the tensile and interlaminar shear stress test results of hybrid FRP re-bar can provide its excellent tensile strength-strain and interlaminar stress-strain behavior.

• 한국표면공학회지
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• 제51권5호
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• pp.271-276
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• 2018

The effects of activator ion on the structural, morphological, and optical properties of $LaNbO_4:RE^{3+}$ (RE = Dy, Dy/Sm, Sm) phosphors were investigated. X-ray diffraction patterns exhibited that all the phosphors showed a monoclinic system with a main (112) diffraction peak, irrespective of the concentration and type of activator ions. The grain size showed a slightly decreasing tendency as the concentration of $Sm^{3+}$ ions increased. The excitation spectra of the $LaNbO_4:Dy^{3+}$, $Sm^{3+}$ phosphor powders consisted of a strong charge transfer band centered at 259 nm in the range of 220-290 nm and five weak peaks. The emission spectra of the $La_{0.95}NbO_4$:5 mol% $Dy^{3+}$ phosphors exhibited two intense yellow and blue bands centered at 575 nm and 479 nm respectively, which resulted from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ and $^4F_{9/2}{\rightarrow}^6H_{15/2}$ transitions of $Dy^{3+}$. As the concentration of $Sm^{3+}$ was increased, the intensity of the yellow emission band was gradually decreased, while those of orange and red emission bands centered at 604 and 646 nm began to appear and reached maxima at 5 mol%, and then decreased rapidly with further increases in the $Sm^{3+}$ concentration. These results indicated that white light emission could be realized by controlling the concentrations of the $Dy^{3+}$ and $Sm^{3+}$ ions incorporated into the $LaNbO_4$ host crystal.

• 대한본초학회지
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• 제27권1호
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• pp.51-58
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• 2012

Objectives : This study was performed to investigate effect of evodiae fructus on acute reflux esophigitis rat induced by pylorus and forestomach ligation operation. Methods : Twenty-four laboratory rats were divided four groups and each group had six rats ; normal intact group, acute reflux esophagitis (RE) control group, two experiment RE group treated extract of evodiae fructus 600 mg/kg (EEF600) and 300 mg/kg (EEF300). All rats was fasted for 18 hr but free water, we induced RE by pylorus and forestomach ligation operation. Intact group and RE control group rats were orally administered a distilled water and two experiment groups were orally administed with EEF 600 mg/5ml/kg and 300 mg/5ml/kg. One hour after, rats were anesthetized, intact group was cut the abdomen open and sutured with 2.0 silk thread. RE control group and EEF group were cut the abdomen open, ligated pyloric canal and forestomach with 2.0 silk thread and sutured. Six hour after the operation, rats were sacrified, collected bloods in the abdominal vein, disectted a esophagus and stomach. The stomach was washed a 1 ml PBS and the esophagus was cut longitudinally and pictured a innter mucosa area to research damages in esophagus. Results : The esophagic tissue damage percentage of reflux esophagitis rat was increased compared to that of normal intact group. But esophagic damage percentage of EEF 600 were significantly decreased compared to that of RE control group. But there was no difference on gastric juice pH between control RE, alpha-tocopherol administration rat group and EEF administration rat group. In esophagus of RE control rat, gastric damage occurred severely and injury percentage of mucosa were increased, but EEF 600 mucous inflammatory damage percentage was significantly compared to that of RE control group. Proinflammatory cytokines such as TNF-alpha, IL-1beta and IL-6 in serum on RE control group were markedly grew than those of intact rat, those of vechicle group treated with EEF 600 and EEF 300 were remarkably decreased compared to production of proinflammatory cytokine of RE control group. In microscopic observation, intact group rat had no hyperemia, mucous injury and exclusion, ulcer and edema. But it could showed mucosa damages, submucosa edema and ulcer in RE control. However, administration of EEF 600 and EEF 300 made esophagus have less inflammation and injury by gastric acid. Conclusions : The results suggest that antiinflammatory Effect of EEF could attenuate the severity of reflux esophagitis and prevent the esophageal mucosal damage, and validate its therapeutic use in esophageal reflux disease.

• 건축역사연구
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• 제25권5호
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• pp.51-62
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• 2016

Since the recent Hanok boom in Korea, Contemporary Hanok has been evolving in terms of structure, space, form, etc. To get a comprehensive understanding of the diversified Contemporary Hanok, this paper aims at its type classification by analyzing architects' designs since 2000. The criteria for the classification are two: (1) renovation [Re] or new construction [New]; and (2) degree of Contemporary Hanok's deviation from the traditional Hanok's standard - maintaining the traditional form [Main]; changing space within the traditional form [Space]; changing the traditional frame [Frame]; and juxtaposing the traditional and the modern [Combi]. From the two criteria, this paper deduced eight types of Contemporary Hanok, named respectively: Re-Main, New-Main, Re-Space, New-Space, Re-Frame, New-Frame, Re-Combi, and New-Combi, and studied their cases. It can be argued that various aspects of Contemporary Hanok and their critical meanings were well-investigated through this type classification and case-studies.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.51-52
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• 2018

Selective oxidation of RE elements from the U/RE metal ingot was studied in this paper using electrochemical process. Constant potential of -1.7V was applied between anode and cathode, where the potential value corresponds to standard potentials between actinide and rare earth materials. When the current values approached to nearly 0 mA, the reaction was finished. It is confirmed from the EPMA analysis that only U part of the U/RE ingot was remained. The metal recovered to the zinc cathode was obtained through the distillation process and it is being chemically analyzed in the KAERI analytical laboratory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1984년도 하계학술회의논문집
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• pp.47-51
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• 1984

• Journal of Advanced Marine Engineering and Technology
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• 제34권4호
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• pp.491-499
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• 2010

관군은 열전달기기에서 광범위하게 사용되고 있어서 전열성능 및 압력강하 특성은 오래전부터 다양한 연구가 진행되어왔다. 기존의 관군에 관한 실험 및 해석은 대부분 25~51mm 직경의 전열관을 이용하여 Reynolds 수 $8.000{\leq}Re{\leq}30.000$ 범위에서 수행되었으나 최근에는 직경 1mm 안팎의 미세관으로 관군을 만들어 열교환기의 밀집도를 높이려는 데 관심이 많다. 본 논문에서는 이전에 다루지 않았던 관 외경 1.5mm의 관군의 전열성능을 $3.000{\leq}Re{\leq}7.000$ 범위에서 전산유체역학을 이용하여 평가하고 기존의 연구 결과들과 비교하였다. 그 결과 튜브직경이 1.5mm인 관군의 열전달계수와 압력손실계수는 $3.000{\leq}Re{\leq}7.000$ 범위에서도 기존의 Zukauskas 상관식과 최대 4.7% 차이 이내로 일치하였다. 또한 튜브의 횡방향 간격을 줄여서 각 열의 전열성능을 높일 수 있음을 확인하였다.

• 천문학회지
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• 제51권6호
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• pp.185-195
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• 2018

Galaxy clusters are known to host many active galaxies (AGNs) with radio jets, which could expand to form radio bubbles with relativistic electrons in the intracluster medium (ICM). It has been suggested that fossil relativistic electrons contained in remnant bubbles from extinct radio galaxies can be re-accelerated to radio-emitting energies by merger-driven shocks via diffusive shock acceleration (DSA), leading to the birth of radio relics detected in clusters. In this study we assume that such bubble consist primarily of thermal gas entrained from the surrounding medium and dynamically-insignificant amounts of relativistic electrons. We also consider several realistic models for magnetic fields in the cluster outskirts, including the ICM field that scales with the gas density as $B_{ICM}{\infty}n^{0.5}_{ICM}$. Then we perform time-dependent DSA simulations of a spherical shock that runs into a lower-density but higher-temperature bubble with the ratio $n_b/n_{ICM}{\approx}T_{ICM}/T_b{\approx}0.5$. We find that inside the bubble the shock speed increases by about 20 %, but the Mach number decreases by about 15% in the case under consideration. In this re-acceleration model, the observed properties of a radio relic such as radio flux, spectral index, and integrated spectrum would be governed mainly by the presence of seed relativistic electrons and the magnetic field profile as well as shock dynamics. Thus it is crucial to understand how fossil electrons are deposited by AGNs in the ICM and how the downstream magnetic field evolves behind the shock in detailed modeling of radio relics.