• Progress in Superconductivity
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• 제14권1호
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• pp.60-65
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• 2012

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. A 35 kWh class SFES module was designed and constructed as part of a 100kWh/1MW class SFES composed of three 35 kWh class SFES modules. The 35 kWh class SFES is composed of a main frame, superconductor bearings, a composite flywheel, a motor/generator, electro-magnetic bearings, and a permanent magnet bearing. The high energy density composite flywheel is levitated by the permanent magnet bearing and superconductor bearings, while being spun by the motor/generator, and the electro-magnetic bearings are activated while passing through the critical speeds. Each of the main components was designed to provide maximum performance within a space-limited compact frame. The 35 kWh class SFES is designed to store 35 kWh, with a 350 kW charge/discharge capacity, in the 8,000 ~ 12,000 rpm operational speed range.

• Wind and Structures
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• 제38권4호
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• pp.277-293
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• 2024

The recorded thunderstorm winds at a point contain tri-directional components. The probabilistic characteristics of such recorded winds in terms of instantaneous mean wind speed and direction, and the probability distribution and the time-frequency dependent crossed and non-crossed power spectral density functions for the high-frequency fluctuating wind components are unclear. In the present study, we analyze the recorded tri-directional thunderstorm wind components by separating the recorded winds in terms of low-frequency time-varying mean wind speed and high-frequency fluctuating wind components in the alongwind direction and two orthogonal crosswind directions. We determine the time-varying mean wind speed and direction defined by azimuth and elevation angles, and analyze the spectra of high-frequency wind components in three orthogonal directions using continuous wavelet transforms. Additionally, we evaluate the coherence between each pair of fluctuating winds. Based on the analysis results, we develop empirical spectral models and lagged coherence models for the tri-directional fluctuating wind components, and we indicate that the fluctuating wind components can be treated as Gaussian. We show how they can be used to generate time histories of the tri-directional thunderstorm winds.

• Animal cells and systems
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• 제1권3호
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• pp.521-526
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• 1997

We isolated a mouse nck cDNA from the thymus cDNA expression library. The cDNA encodes a 377 amino acid protein and displays 97% amino acid sequence identity to human oncogenic protein nck, which is composed almost exclusivelv of three src homology 3 (SH3) domains and one SH2 domain. The sequence analysis also showed that the isolated cDNA is the mouse counterpart of the human nck and different from the mouse grb4, which has been reported to be highly similar to the human nck and, therefore considered as a mouse nck, Northern blot analysis showed that the transcript of the gene was 1.8 kb and was highly expressed in the testis, thymus, and brain but moderately in the liver and lymph node. Western blot analysis showed that the size of the protein was about 47 kDa. Overexpression of the mouse Nck transformed a mouse fibroblast cell line, NIH3T3. The results clearly indicate that normal nck gene has transforming ability and provide an argument against a suggested possibility that the transforming ability of the human nck gene is due to a mutation(s) in the gene.

• KEPCO Journal on Electric Power and Energy
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• 제4권1호
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• pp.25-31
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• 2018

A boiler system transforms water to pressured supercritical steam which drives the running of the turbine to rotate in the generator to produce electricity in power plants. Materials for building the tube system face challenges from high temperature creep damage, thermal fatigue/expansion, fireside and steam corrosion, etc. A database on the creep resistance strength and steam oxidation of the materials is important to the long-term reliable operation of the boiler system. Generally, the ferritic steels, i.e., grade 1, grade 2, grade 9, and X20, are extensively used as the superheater (SH) and reheater (RH) in supercritical (SC) and ultra supercritcal (USC) power plants. Currently, advanced austenitic steel, such as TP347H (FG), Super304H and HR3C, are beginning to replace the traditional ferritic steels as they allow an increase in steam temperature to meet the demands for increased plant efficiency. The purpose of this paper is to provide the state-of-the-art knowledge on boiler tube materials, including the strengthening, metallurgy, property/microstructural degradation, oxidation, and oxidation property improvement and then describe the modern microstructural characterization methods to assess and control the properties of these alloys. The paper covers the limited experience and experiment results with the alloys and presents important information on microstructural strengthening, degradation, and oxidation mechanisms.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1051-1054
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• 2004

The structural transformation behavior of $Na_2Ti_3O_7$ by hydrolysis was investigated in mild and strong acidic aqueous medium. Compared with $K_2Ti_4O_9,\;Na_2Ti_3O_7$ exhibits quite different structural and morphological transformation behavior despite their similar layered structural characteristics. $TiO_2(B)$ obtained by heat treatment of $H_2Ti_3O_7\;at\;350^{\circ}C$ transforms to rutile $H_2Ti_3O_7\;at\;900^{\circ}C$. This temperature is much lower than $1200{\circ}C$, the temperature for anatase to rutile transition when $K_2Ti_4O_9$ is used as a starting titanate. A rectangular rod shape and size of $TiO_2(B)$ particles obtained from $Na_2Ti_3O_7$ is also different from a fibrous structure of $TiO_2(B)$ prepared using $K_2Ti_4O_9$. Rutile crystals of 100 nm diameter with a corn-like morphology and large surface area are directly obtained when the hydrolysis of $Na_2Ti_3O_7$ is carried out at $100^{\circ}C$ in a strong acid solution. The structure of starting titanates and the hydrolysis conditions are an important factor to decide the particle size and morphology of $TiO_2(B)\;and\;TiO_2$.

• 한국수산과학회지
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• 제28권4호
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• pp.469-474
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• 1995

[ $3\beta-$ ]히드록시-$\Delta^5$-스테로이드 탈수소효소 ($3\betaβ-HSD,$ $3\beta-hydroxy-\Delta^5-steroid\;dehydrogenase$ $\Delta^5$-스테로이드$\rightarrow\Delta^4$-스테로이드로의 대사경로에 관여하는 효소)에 대하여 특이적 저해제인 cyanoketone과 trilostane의 저해 효과가 $^3H-pregnenolone$ 전구체를 이용하여 무지개송어 난소에서 분리한 여포층, 협막층(theca layers)을 대상으로 비교 관찰되었다. Pregnenolone으로부터 $17\alpha-hydroxyprogesterone$으로의 대사과정에서 주요 효소인 $(3\beta-HSD$ 활성은cyanoketone $10^{-6}$과 $10^{-5}\;M$, 그리고 trilostane $10^{-5}$과 $10^{-4}\;M$의 농도에서 억제되었으며, trilostane이 cyanoketone보다 더 효과적인 억제반응을 보이는 것으로 나타났다. Pregnenolone으로부터 $\Delta^4$-스테로이드 대사물 축적에 대한 trilostane의 저해작용은 사용한 농도 즉, $10^{-8}, 10^{-7}, 10^{-6}$ 그리고 $10^{-5}\;M$에 비례하여 나타났으나 완전한 저해효과는 보이지 않았다.

• 한국자기공명학회논문지
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• 제11권2호
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• pp.95-109
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• 2007

Vanadium-incorporated aluminophosphate microporous molecular sieve VH-SAPO-42 has been studied by electron spin resonance(ESR) and electron spin-echo modulation (ESEM) spectroscopies to determine the vanadium location and interaction with various adsorbate molecules. The results are interpreted in terms of V(IV) ion location and coordination geometry. Assynthesized VH-SAPO-42 contains only vanadyl species with distorted octahedral or trigonal bipyramidal coordination. Vanadium incorporated into H-SAPO-42 occupied extra-framework site. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is identified as a $VO(H_2O)_2^{2+}$ complex coordinated to three framework oxygen atoms bonded to aluminum. When hydrated VH-SAPO-42 is dehydrated at elevated temperature by calcination, species A loses its water ligand and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$ at high temperature, thus suggesting oxidation of $V^{4+}$ to $V^{5+}$. When dehydrated VH-SAPO-42 makes contact with $D_2O$ at room temperature, the ESR signal of species A is regained. The species is assumed as a $VO(O_f)_3(D_2O)_2$ by considering three framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-42 results in another new vanadium species D, which is identified as a $VO(CD_3OH)_2$ complex. When deuterated ethylene is adsorbed on dehydrated VH-SAPO-42, another new vanadium species E identified as a $VO(C_2D_4)^{2+}$, is observed. Possible coordination geometries of these various complexes are discussed.

• 한국재료학회지
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• 제13권7호
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• pp.453-459
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• 2003

In this paper the effect of interstitial heat treatment on the microstructure and mechanical properties was examined both in the 0.15C-6Mn steels and 0.15C-6Mn steels added with Nb or Ti. This result will be applied into the development of a steel which has the properties of high strength and high ductility resulted from the transformation induced plasticity. The strength-elongation combination was increased as the holding time was increased when the temperature is at $625^{\circ}C$. However, the strength-elongation combination was decreased sharply as the holding time was increased when the temperature is at $675^{\circ}C$. The tensile strength and elongation of a reverse transformed steels added with Ti or Nb was 93 kg/$\textrm{mm}^2$ and 40%, respectively. This steel shows higher strength more than 10% of the 0.15C-6Mn steel without loss of ductility. The autenite formed from the reverse transformed treatment has a fine lath type, which has the width size of 0.1-0.3 $\mu\textrm{m}$. The TRIP sequence normally transforms the austenite to martensite, however, some of the sequence will produce retained austenite \longrightarrow deformation twin \longrightarrow martensite

• 한국게임학회 논문지
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• 제11권2호
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• pp.161-166
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• 2011

본 논문에서는 동작인식 위한 정확한 배경 분할 및 특징점 추출 방법을 제안한다. 배경 분할 과정에서는 먼저, HSV 입력 이미지를 RGB 색상 공간에서 HSV 색상 공간으로 변환한 뒤, H와 S 값에 대한 두 개의 임계치를 사용하여 살색 영역을 분할, 프레임간의 차영상을 이용하여 움직임이 있는 영역을 추출한다. 차영상에서 발생하는 잔상 영역을 제거하기 위하여 헤시안 어파인 영역 검출기를 적용하고, 잡음이 제거된 차 영상과 살색 영역의 이진화 영상을 이용하여 사람의 동작이 나타나는 영역을 분할한다. 특징점 추출 과정은 전체 영상을 블록 단위로 나눠서 각 블록 안에서 분할된 영상에 포함되는 픽셀들의 중점을 구하여 특징점을 추출한다. 실험결과 복잡한 환경에서도 정확한 배경 분할과 사용자 동작을 대표하는 특징점 추출이 약 12 fps로 가능함을 알 수 있었다.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.138-154
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• 2005

Vanadium-incorporated aluminophosphate molecular sieve $VO^{2+}-SAPO-5$ was studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium structure and interaction with various adsorbate molecules. It was found that the main species at low concentration of vanadium is a monomeric vanadium units in square pyramidal or distorted octahedral coordination, both in oxidation state (IV) for the calcined hydrated material and in oxidation state (V) for the calcined material. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. It is suggested as a $VO(H_2O)_3^{2+}$ complex coordinated to two framework oxygen bonded aluminum. When calcined, hydrated $VO^{2+}-}SAPO-5$ is dehydrated at elevated temperature, a species loses its water ligands and transforms to $VO^{2+}$ ions coordinated to two framework oxygens (species B). Species B reduces its intensity, significantly after treatment with $O_2\;at\;600^{\circ}C$ for 5 h, thus suggesting oxidation of $V^{4+}\;to\;V^{5+}$. When dehydrated $VO^{2+}-SAPO-5$ contacts with $D_2O$ at room temperature, the EPR signal of species A is observed. Thus species assumed as a $VO^{2+}(O_f)_2(D_2O)_3$, by considering two framework oxygens. Adsorption of deuterated ethanol, propanol on dehydrated $VO^{2+}_{-}SAPO-5$ result in another new vanadium species E and F, respectively, which are identified as a $VO^{2+}-(CH_3CH_2OD)_3,\;VO^{2+}-(CH_3CH_2CH_2OD)_2$ complex. When deuterated benzene is adsorbed on dehydrated $VO^{2+}-SAPO-5$, another new vanadium species G, identified as a $VO^{2+}-(C_6D_6)$ is observed. Possible coordination geometries of these various complexes are discussed.