• Applied Microscopy
• /
• 제50권
• /
• pp.2.1-2.7
• /
• 2020

Electron energy loss spectroscopy (EELS) is an analytical technique that can provide the structural, physical and chemical information of materials. The EELS spectra can be obtained by combining with TEM at sub-nanometer spatial resolution. However, EELS spectral information can't be obtained easily because in order to interpret EELS spectra, we need to refer to and/or compare many reference data with each other. And in addition to that, we should consider the different experimental variables used to produce each data. Therefore, reliable and easily interpretable EELS standard reference data are needed. Our Electron Energy Loss Data Center (EELDC) has been designated as National Standard Electron Energy Loss Data Center No. 34 to develop EELS standard reference (SR) data and to play a role in dissemination and diffusion of the SR data to users. EELDC has developed and collected EEL SR data for the materials required by major industries and has a total of 82 EEL SR data. Also, we have created an online platform that provides a one-stop-place to help users interpret quickly EELS spectra and get various spectral information. In this paper, we introduce EEL SR data, the homepage of EELDC and how to use them.

• 터널과지하공간
• /
• 제21권4호
• /
• pp.297-306
• /
• 2011

본 연구에서는 지하 압축공기에너지 저장공동 주변 지하수 및 압축공기의 유체유동과 열전달 거동 해석을 위한 다상다성분 열유동 해석 결과를 이용하여 지하 저장공동의 열역학적 에너지수지 분석을 통한 에너지 효율평가를 실시하였다. 복공재인 콘크리트 라이닝이 충분한 기밀성능을 발휘할 경우, 주입 압축과정에서 저장공동으로부터 손실되는 에너지의 대부분은 콘크리트 라이닝 및 주변 암반에의 열전도를 통해 발생함을 확인하였다. 지하 압축공기에너지 저장공동의 에너지 효율은 압축공기 주입온도에 민감한 결과를 보였으며, 주입온도가 주변 암반의 온도에 근사할 경우, 손실된 에너지의 대부분이 토출 팽창과정에서 저장공동으로 유입 회수되는 결과를 보였다. 한편, 콘크리트 라이닝의 열전도특성이 저장공동의 에너지효율에 미치는 영향은 크지 않았다.

• 한국산학기술학회논문지
• /
• 제10권12호
• /
• pp.3748-3754
• /
• 2009

원자력발전소에서 냉각재상실사고이후 원자로건물집수조 여과기에서 화학적 영향에 의한 수두손실 변화를 관찰하기 위하여 시험장치에서 단기살수조건, 장기살수조건, 및 화학적 영향을 주는 물질이 없는 조건에 대해 30일 동안 종합적인 수두손실 시험을 수행하였다. 시험결과는 수두손실이 살수조건에 따라 노출된 화학적 영향을 주는 물질의 양에 크게 의존함을 보였다. 시험종료후 수거된 침전물의 XRD 분석은 침전물이 주로 인산화합물임을 보였다. 수두손실과 용해된 화학종의 비교결과는 화학적 영향을 주는 물질 중에서 Al과 Zn의 부식이 시험 초기에 높은 수두 손실 증가율의 원인이 됨을 보였다. 금속 시편에 부동피막이 형성된 이후에 수두손실 증가율은 감소하지만 지속적으로 수두손실이 증가하는 현상은 NUKON 및 콘크리트에서 침출반응에 의해 발생하는 Si, Mg, 및 Ca이 침전물을 형성하는 반응에 기인함을 보였다.

• Journal of Korean Vacuum Science & Technology
• /
• 제4권1호
• /
• pp.1-5
• /
• 2000

The C 1s photoelectron energy loss spectra of tris (8-hydroxy-quinoline) aluminum (Alq$_3$) and N,N'-diphenyl-N,N'-bis (3-methyl phenyl)-1,1'-bi-phenyl-4,4'-diamine (TPD) thin films have been investigated. Two major loss structures, namely the plasmon dominated loss lines and shake-up satellites, have been observed. The shake-up spectrum of the C 1s photoelectron line is directly related to the $\pi$-$\pi$$\^$*/ energy gap of the molecule which plays an important role in organic electroluminescent materials. The molecular orbitals of Alq$_3$ and TPD and their major components, quinolime and benzene, have been calculated with the AMI semi-empirical method. The amount of the plasma-dominated loss of Alq$_3$ and TPD, which has to do with the delocalization of electrons through the molecule, was about 24 eV, alike in both cases. The main peak of the C 1s shake-up spectrum of Alq$_3$ and TPD, however, was 5.2 eV and 6.8 eV respectively. It was found that the main shake-up peak reflects more the local $\pi$\longrightarrow$\pi$$\^$*/ transition of quinoline and benzene component rather than the excitation of the whole molecule of Alq$_3$ and TPD. The C 1s shake-up spectra, however, revealed some correlation with the optical energy gap of the organic eletroluminescent materials.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제52권3호
• /
• pp.130-136
• /
• 2003

Crowbar system Vacuum switches, widely used In a pulsed power system, could use the magnetic force to prevent the electrode damage. Vacuum switches using the magnetic forces are classified roughly into RMF(Radial Magnetic Field) and AMF(Axial Magnetic Field) type. The RMF type switches restrain a main electrode from aging due to high temperature and high density arc by rotating the arc which is driven by the Lorenz force. The AMF type switches generate axial magnetic field which decreases the electrode damage by diffusing arc. In this paper, we present the energy loss characteristics of both RMF and AMF type switches which are made of CuCr(75:25 wt%) electrodes. The time-dependent dynamic arc resistance of high-current pulsed discharge in a high vacuum chamber(~10$^{-6}$ Torr). which occurs in RMF and AMF type switches, was obtained by solving the circuit equation using the measured values of the arc voltage and current. In addition, we compared energy loss characteristics of both switches. Based on our results, it was found that the arc voltage and the energy loss of an AMF type switch are lower than a RMF type switch.

• 신재생에너지
• /
• 제20권2호
• /
• pp.35-43
• /
• 2024

A pump turbine is a technically matured option for energy production and storage systems. At the off-design operating range, the pump turbine succumbed to flow instabilities, which correlated with the pump turbine geometry. A low specific speed pump turbine was designed and modified according to the impeller blade angle. Reynolds-Average Navier-Stokes is carried out with a shear stress transport turbulence model to evaluate the detailed flow characteristics in the pump turbine. The impeller blade inlet angle (𝛽₁) and outlet angle (𝛽₂) are used to evaluate hydraulic loss in the pump turbine. When 𝛽₁ changed from low to high value, the maximum efficiency is increased by 4.75% in turbine mode. The S-Curve inclination is reduced by 8% and 42% for changes in 𝛽₁ and 𝛽₂ from low to high values, respectively. At α = 21°, the shock loss coefficient (𝜁_s) is reduced by 16% and 19% with increases of 𝛽₁ and 𝛽₂ from low to high values, respectively. When 𝛽₁ and 𝛽₂ values increased from low to high, the impeller friction coefficient (𝜁_f) increased and decreased by 20% and 8%, respectively. Hence, the high 𝛽₂ effectively reduced the loss coefficient and S-Curve inclination.

• 조명전기설비학회논문지
• /
• 제12권1호
• /
• pp.117-125
• /
• 1998

본 논문에서는 전류시 유도전동기의 누설 인덕턴스 및 직류 링크 인덕터에서 발생하는 손실과 스너버 회로에서 발생하는 손실을 효과적으로 전원 및 부하로 회생하는 새로운 VCC-3를 제안하였으며, VCC-1, VCC-2 및 VCC-3를 3상 유도전동기에 적용하여 부하의 입·출력 특성과 궤환량 등을 측정, 비교·검토한 결과, VCC-3 방식의 GTO CSI가 효율개선 및 안전성 면에서 우수하다는 것을 입증하였다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2014년도 추계학술대회
• /
• pp.971-974
• /
• 2014

본 논문은 최근의 에너지 절감의 사회적 관심을 반영한다. LED 시장은 지속적 성장을이어가고 있다. 그러나 현재 led 조명은 빛 에너지 변환율이 높지 않다.이러한 LED 조명에 대하여 빛 변환 에너지 절감 방법을 제시하고자 한다. 현재의 LED 조명은 전력 변화를 각각의 조명에서 이루어지므로 인한 변환 손실의 누적이 발생한다. 손실 누적 발생을 최소화 하여 에너지 손실 성능 개선을 얻을 수 있도록 한다.

• 한국수소및신에너지학회논문집
• /
• 제24권5호
• /
• pp.428-436
• /
• 2013

Attrition characteristics of $CO_2$ absorbents for pre-combustion $CO_2$ capture were investigated to check attrition loss of those absorbents and to determine solid circulation direction and the better $CO_2$ absorbent. The cumulative attrition losses of two absorbents increased with increasing time. However, attrition loss under a humidified condition was lower than that under a non-humidified condition case. Between two absorbents, attrition loss of PKM1-SU absorbent was higher than that of P4-600 absorbent. The average particle sizes of the attrited particles were less than $2.5{\mu}m$ for two absorbents under a non-humidified condition case, and therefore, we could conclude that the main mechanism of attrition for two absorbents is not fragmentation but abrasion. Based on the results from the test for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor. Attrition loss and make-up rate of two absorbents were compared based on the results from $CO_2$ sorption capacity tests and attrition tests. Required make-up rate of P4-600 absorbent was lower than that of PKM1-SU absorbent. However, more detail investigation on the optimum regeneration temperature, manufacturing cost, solid circulation rate, regeneration rate, and long-term sorption capacity should be considered to select the best $CO_2$ absorbent.

• Nutritional Sciences
• /
• 제5권4호
• /
• pp.221-227
• /
• 2002

The objective of this study was to examine the effects of a weight loss program on the degree of obesity and levels of resting energy expenditure (REE) in overweight subjects according to their mitochondrial uncoupling protein 2 (UCP 2) genotype. Twenty-three subjects with a body mass index (BMI) greater than 27 were recruited from the Obesity Clinic of the Kyung-Hee University Hospital during the period of December 2000 - August 2001. The subjects were genotyped for the exon 8 allele; 15 subjects were found to be of del/del genotype, 8 were del/ins, and none were of ins/ins genotype. No significant association was found between the different UCP 2 genotypes and the initial levels of weight, fat mass (FM), lean body mess (LBM), BMI, REE, and REE/LBM ratio. After 12 weeks of a weight loss program, body weight and FM were significantly decreased, while LBM, total body water (TBW), and REE were not changed, irrespective of UCP 2 genotype. Initial fasting plasma levels of albumin, glucose, triglyceride, lipoprotein cholesterol, insulin, free triiodo-thyronine (T3), free fatty acid (FFA), and leptin were not different according to the UCP 2 genotype; furthermore, these blood parameters were not changed after the 12-week weight loss program. However, plasma levels of leptin decreased in both the del/del and ins/del genotypes, from 18.7 ng/ml to 13.4 ng/ml (p<.05), and from 18.1 ng/ml to 13.9 ng/ml (p＜.05), respectively, after the weight loss program. In conclusion, this study found no significant association between the del/del or del/ins UCP 2 genotypes and differing levels of REE or differing degrees of obesity, either before or after a weight loss program. This study provided evidence that a well- managed weight loss program could maintain levels of REE, which plays an important role in the maintenance of energy balance.