A durable nanocatalyst of potassium-doped iron-carbide/alumina for significant production of linear alpha olefins via Fischer-Tropsch synthesis

Park, Ji Chan,Jang, Sanha,Rhim, Geun Bae,Lee, Jin Hee,Choi, Hyunkyoung,Jeong, Heon-Do,Youn, Min Hye,Lee, Dong-Wook,Koo, Kee Young,Kang, Shin Wook,Yang, Jung-Il,Lee, Ho-Tae,Jung, Heon,Kim, Chul Sung,Ch Elsevier 2018 Applied catalysis. A, General Vol.564 No.-

<P><B>Abstract</B></P> <P>Improvement of activity, selectivity, and stability of the catalyst used in Fischer-Tropsch synthesis (FTS) to produce targeted hydrocarbon products has been a major challenge. In this work, the potassium-doped iron-carbide/alumina (K-Fe<SUB>5</SUB>C<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>), as a durable nanocatalyst containing small iron-carbide particles (∼ 10 nm), was applied to high-temperature Fischer-Tropsch synthesis (HT-FTS) to optimize the production of linear alpha olefins. The catalyst, suitable under high space velocity reaction conditions (14–36 N L g<SUB>cat</SUB> <SUP>−1</SUP> h<SUP>−1</SUP>) based on the well-dispersed potassium as an efficient base promoter on the active iron-carbide surface, shows very high CO conversion (up to ∼90%) with extremely high activity (1.41 mmol<SUB>CO</SUB> g<SUB>Fe</SUB> <SUP>−1</SUP> s<SUP>−1</SUP>) and selectivity for C<SUB>5</SUB>–C<SUB>13</SUB> linear alpha olefins.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The potassium-doped iron-carbide/alumina nanocatalyst was prepared for effective production of linear alpha olefins. </LI> <LI> The active iron-carbide nanoparticles (∼10 nm) with potassium on gamma-alumina could enhance catalytic performance. </LI> <LI> The catalyst showed high stability and activity for high-temperature Fischer-Tropsch synthesis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A potassium-doped iron-carbide/alumina nanocatalyst shows very high CO conversion (∼90%) and significant productivity for C<SUB>5</SUB>–C<SUB>13</SUB> linear alpha olefins in Fischer-Tropsch synthesis under high space velocity conditions.</P> <P>[DISPLAY OMISSION]</P>

Non-flammable organic liquid electrolyte for high-safety and high-energy density Li-ion batteries

Pham, Hieu Quang,Lee, Hee-Yeol,Hwang, Eui-Hyung,Kwon, Young-Gil,Song, Seung-Wan Elsevier 2018 Journal of Power Sources Vol.404 No.-

<P><B>Abstract</B></P> <P>With increased energy density of rechargeable lithium-ion batteries for powering smart phones and electric vehicles and for their long range use, battery safety becomes more important than ever. This aspect motivated us to develop non-flammable liquid electrolyte that removes the risk of battery fire and explosion, which is urgently needed. Battery energy density and performance however should not be sacrificed to achieve just the safety. Here we report for the first time a rational design of non-flammable carbonate-based organic liquid electrolyte to satisfy safety, energy density and performance simultaneously. Our novel electrolyte, composed of 1 M lithium hexafluorophosphate salt and propylene carbonate and fluorinated linear carbonate co-solvents, at unmeasurable flash point does not fire representing non-flammable safe batteries but permits high-voltage stability to enable high-voltage charge of lithium-rich layered oxide cathode up to 5.0 V, high-energy density of 856 Wh per kg of cathode active mass and stable charge-discharge cycling performance of full-cell with graphite anode, in contrast to rapid performance fade of flammable conventional electrolyte system. The discovery of non-flammable carbonate-based organic liquid electrolyte opens up a new avenue to high-safety and high energy-density lithium-ion batteries for electric vehicles and advanced energy-storage applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rational design of non-flammable carbonate-based organic liquid electrolyte. </LI> <LI> High energy density of non-flammable full-cell with Li-rich layered oxide cathode. </LI> <LI> Preserved cathode structure and stable interface with non-flammable electrolyte. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

시네마 로보틱스 그리고 디지털 미장센

이석창(Lee, Sukchang),최원호(Choi, Wonho) 한국영화학회 2021 영화연구 Vol.- No.90

로봇(Robot)은 생산성 증대를 위해 다양한 분야에서 활용되고 있다. 영화제작의 분야에서도 로봇의 시각적 표현과 차별성의 극대화라는 측면이 강조되어 인공지능, IoT, 빅데이터 등 지능정보화 산업 및 문화콘텐츠 산업과 함께 새로운 형태의 영상콘텐츠 생산에 영향을 미치고 있다. 시네마 로보틱스(Cinema Robotics)는 컴퓨터를 사용하여 정교하고 정확하게 카메라 움직임을 제어하는 영상 촬영 장비로 로봇 암 제어기술과 ICT(Information and Communications Technology, 정보 통신 기술)의 결합과 함께 촬영기술의 진보를 이루어내며 새로운 영상표현의 지평을 넓혔다. 그러나 시네마 로보틱스가 국내에서 영화제작에 본격적으로 활용되고 있음에도 불구하고 이에 대한 본격적인 제작기법과 영상미학 등에 관한 연구는 미흡한 실정이다. 본 논문은 시네마 로보틱스의 고속 촬영과 High-Speed 카메라 움직임을 통해 나타나는 특징을 미장센(Mise-en-Scène)의 관점에서 해석하였고, 그 과정을 통해 시네마 로보틱스가 재현 방식의 확장과 느린 화면의 비선형적 경험 및 전지적 시점이라는 특징을 드러내고 있음을 발견하였다. 시네마 로보틱스는 고속 촬영으로 숏테이크 영상의 시간을 확장하여 롱테이크 영상으로 변환시킬 수 있다. 빠르고 정확하게 제어되는 카메라 움직임은 롱테이크에서 아웃포커스가 물리적으로 가능한 환경을 조성하고 줌 인과 트랙 아웃의 결합이 유기적으로 일어나게 하여 영상 이미지의 심도를 조형적인 측면에서 왜곡시킴으로써 재현 방식의 확장을 이루어 낼 수 있게 만든다. 또한 고속 촬영과 High-Speed 카메라 움직임은 느린 화면의 일그러진 시간성과 찰나의 순간을 다각도에서 바라보는 전지적 시점으로 비선형적 체험을 관객에게 제공한다. 비가시적인 영역을 보여주는 고속 촬영은 시간의 확장으로 나타나는 비관습적인 장면으로 느린 화면을 제공하며 수용자의 관점을 변화시켜 수용자의 논리적인 세계를 무너뜨리고, 느린 장면은 추상적 특성을 발포하며 관객의 흥미를 유발하는 미장센으로 거듭난다. 또한, 시네마 로보틱스는 High-Speed 카메라 움직임으로 느린 화면 내에서 다각도로 피사체의 운동 에너지를 포착한다. 그리하여 관객은 인간의 눈으로 볼 수 없던 사물의 움직임을 여러 각도에서 살펴볼 수 있는 전지적 시점을 경험하게 된다. Robot is utilized in various fields in order to increase productivity. In the area of visual content production, the demand for new forms of visual content production is increasing along with the intelligent information industry involving artificial intelligence, IoT, and big-data and the cultural content industry as emphasizing the robot’s aspect of the visual expression and the maximizing differentiation. Cinema Robotics, which is a video recording equipment that uses a computer to precisely and accurately control camera movements, expanded the area of new visual expression by making progress in filming technology with the combination of robotic arm control technologies and ICT(Information and Communications Technology). However, even though Cinema Robotics is actively used in film production, research on production techniques and visual aesthetics is insufficient. This paper interprets the characteristics of Cinema Robotics through high-speed cinematography and High-Speed camera movements on the perspective of Mise-en-Scène, and it discovered Cinema Robotics has the characteristics of expansion of representation, non-linear experience of slow motion, and omniscient viewpoint. Cinema Robotics extends the time of short-take video by high speed cinematography and converts it into long-take video, and with fast and precisely controlled camera movements, it creates an environment in which out-of-focus is physically possible and expands the reproduction method. In addition to, high speed cinematography and High-Speed camera movements provide the audience with a non-linear experience with an omniscient perspective that sees the distorted time and a moment of slow motion from multiple angles. High speed cinematography, which shows the invisible area, breaks down the audience’s logical world as changing the audience’s point of view with slow motion that is showed by an unconventional scene from expanded time. In this way, slow motion is reborn as a mise-en-scène that evokes abstract characteristics and arouses the interest of the audience. Moreover, Cinema Robotics captures the subject’s kinetic energy from multiple angles within a slow motion with High-Speed camera movements. So, the audience experiences an omniscient point of view where they can see the movement of objects from various angles which we cannot see.

고역필터를 사용한 선형압축기 구동용 LPMSM의 새로운 스트로크 계산 기법

전태원,안정렬,이홍희,김흥근,노의철 전력전자학회 2006 전력전자학회 논문지 Vol.11 No.1

Linear compressors with a free piston driven by a linear motor are widely attention in the cooling apparatus such as refrigerator due to the high efficiency. The stroke of piston in the linear compressor driven by LPMSM (Linear Permanent-Magnet Synchronous Motor) can be obtained from integrating the input voltage and current of LPMSM, but it may be diverged due to dc components in the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and dc offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The accurate stroke of a piston can be calculated by compensating for dc offset. The performance of the newly developed stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP. 근래에 선형전동기로 냉장고 등 냉동기기의 압축기 피스톤을 제어하는 선형압축기가 높은 효율 때문에 많이 주목받고 있다. 선형압축기의 피스톤 스트로크는 LPMSM의 입력 전압 및 전류값을 적분하여 구하며, 이 입력 신호에 직류성분이 포함될 경우 스트로크가 발산된다. 본 연구에서는 고역필터 및 직류 옵셋 보상 방식을 사용하여 입력 전압 및 전류의 직류성분에 의한 스토로크의 발산을 방지하는 기법을 제시하였다. 고역필터의 차단주파수에 대한 스트로크의 크기 및 위상과 스트로크에 포함된 직류옵셋 값의 관계를 유도하고, 직류 옵셋 값을 보상하여 정확한 스트로크를 계산한다. 새로 개발된 스트로크 계산방법의 성능은 16비트 DSP 구현된 선형압축기 시스템의 실험을 통하여 확인하였다.

Reactive compensation of long primary HTS‑linear synchronous machines

Keyu Guo,Yaohua Li,Liming Shi,Yumei Du 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5

In propulsion systems requiring high speed and high acceleration, the long primary high-temperature superconducting linear synchronous machine (HTS-LSM) is a competitive candidate, since it can provide steady and high thrust. However, the armature windings on the long primary uncovered by a mover with HTS magnets can cause large flux leakage, which can lead to a high armature reaction voltage and a poor power factor. In this paper, to restrain the armature reaction voltage of the long primary HTS-LSM, compensation windings are proposed for installation on the primary. First, a mathematical model of a five-phase four-pole long primary HTS-LSM is established, and it is determined that the high armature reaction voltage is caused by the large self-inductance of uncovered armature windings. Then, compensation winding is applied in the armature winding to reduce the equivalent self-inductance. Four different compensation winding installation positions are studied and compared. To prevent the current in the compensation windings from affecting the function of the HTSracetrack magnet on the mover, a switch control strategy for the compensation windings is proposed. Finally, prototypes of armature windings with compensation windings are manufactured and the effectiveness of the compensation windings are validated and compared.

$rho$차 역필터 기법을 이용한 OFDM 시스템의 메모리가 없는 비선형 고전력 증폭기의 전치 보상기 설계

임선민,은창수,Lim, Sun-Min,Eun, Chang-Soo 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.2c

본 논문에서는 OFDM 신호의 높은 PAPR과 전력 증폭기의 비선형성에 의한 신호의 왜곡과 스펙트럼의 확산을 방지하기 위하여 $rho$차 역필터 구조를 사용하는 전치 보상기를 구현하는 방안을 제시한다. 메모리가 없는 고전력 증폭기를 다항식으로 모델링 하고 전치 보상기로써 비선형 증폭기 특성의 역모델인 $rho$차 역필터 구조를 이용한다. $rho$차 역필터 구조는 비선형 시스템이 다항식으로 모델링 된다면 다항식의 계수만으로 구현될 수 있으므로 많은 메모리가 필요 없다. 비선형 전력 증폭기 모델의 계수 갱신을 위하여는 LMS, RLS 알고리듬을 모두 사용할 수 있으며 계수의 개수가 적어 수렴 속도가 빠르고 복소 계산이 필요 없으므로 계산도 간단하다. In this paper, we propose a method to implement a predistorter of the $rho$-th order inverse filter structure to prevent signal distortion and spectral re-growth due to the high PAPR (peak-to-average ratio) of the OFDM signals and the non-linearity of high-power amplifiers. We model the memory-less non-linearity of the high-power amplifier with a polynomial model and utilize the inverse of the model, the $rho$-th order inverse filter, for the predistorter. Once the non-linearity is modeled with a polynomial, since we can determine the $rho$-th order inverse filter only with the coefficients of the polynomial, large memory is not required. To update the coefficients of the non-linear high-power amplifier model, we can use LMS or RLS algorithms. The convergence speed is high since the number of coefficients is small, and the computation is simple since manipulation of complex numbers is not necessary.

A Transconductor and Tunable <tex> $G_{m}-C$</tex> High-Pass Filter Linearization Technique Using Feedforward <tex> $G_{m3}$</tex> Canceling

Duksoo Kim,Byungjoon Kim,Sangwook Nam IEEE 2015 IEEE Transactions on Circuits and Systems II: Expr Vol. No.

<P>A linearization technique of a transconductor circuit is proposed in this brief. By adopting a two-path feedforward architecture, the G(m3) component of the transconductor vanishes and a highly linear V -to-I conversion is achieved. This technique consists of self-biased inverters only, and it can be applied to transconductors with differential inputs. It also has an advantage in process scaling and precise bias control is not necessary. A tunableG(m) - C high-pass filter for the baseband of a frequency-modulated continuous-wave radar system is implemented using these linearized transconductors. The filter is synthesized with a high-order admittance method. The designed filter is fabricated in a 0.13-mu m CMOS process. The filter cutoff frequency can be tuned from 0.15 to 0.75 MHz with a current consumption value of 11-36 mA. An in-band input-referred third-order intercept point of + 19.4 dBm and a 1-dB compression point of + 5.35 dBm are measured, demonstrating a highly linear filter operation.</P>

고주파수 난청 환자에서 보청기의 비선형 주파수 압축 기술의 임상적 초기 경험

김진률,박희성,진선화,박우리,조영상,홍성화,문일준 대한이비인후과학회 2016 대한이비인후과학회지 두경부외과학 Vol.59 No.2

Background and Objectives Consonants are uttered in the high frequency range in speech to bring out understanding of our language. As consonants convey most of the word information, listeners with high-frequency hearing loss find it hard to understand speech. Non-linear frequency compression (NLFC) technology compresses and moves higher frequencies into a lower frequency region where better residual hearing is present. The purpose of this study was to evaluate clinical effectiveness of NLFC technology in patients with high-frequency hearing loss. Subjects and Method Twelve ears representing patients with sloping, high-frequency sensorineural hearing loss were involved in this study. Pure-tone audiometry and Threshold Equalizing Noise Test were conducted initially in all subjects. The subjects were tested in the counter-balanced order, and had two months of everyday experience with NLFC on/off before testing took place. A resting period intervened the two phases. Performance was repeatedly evaluated with Sound Field Audiometry, Word Recognition Score, Reception Threshold for Sentences and Korean version of International Outcome Inventory for Hearing Aids. Results Cochlear dead region was detected on 4 kHz of both ears in only one subject. Each subject showed diverse performance and satisfaction with active NLFC condition. Typically, audibility of high-frequency pure-tones improved with NLFC-on condition. However, speech perception both in quiet and noise was not much improved when compared with NLFC-off condition. Conclusion The NLFC technology could improve audibility in high-frequency, but failed to demonstrate benefits regarding speech perception. Further research is needed to validate the effectiveness of the NLFC technology especially in terms of speech intelligibility. Korean J Otorhinolaryngol-Head Neck Surg 2016;59(2):96-103

Design of High-linearity Delay Detection Circuit for 10-Gb/s Communication System in 65-nm CMOS

Kosuke Furuichi,Hiromu Uemura,Natsuyuki Koda,Hiromi Inaba,Keiji Kishine 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.6

This paper describes a method of designing a circuit to detect high-linearity delay at 10 Gb/s. We proposed a transmission system for additional data in previous work, by using a frequency modulation technique. The demodulation characteristics in the receiver strongly depended on data speed. As the data speed gets higher, demodulation characteristics linearity degradation become larger. In this paper, we propose a circuit to provide high-linearity demodulation characteristics by using an emphasis technique which reduces degradation in the demodulated signal. We fabricated the circuit to detect delay with an emphasis technique by using 65- nm CMOS process. The results we obtained from measurements, revealed an integrated circuit (IC) achieved 10% higher linearity than a receiver without emphasis at 10 Gb/s.

세라믹/금속 혼합비가 11층 열장벽 피막의 고온특성에 미치는 영향

남영민,송요승 한국항공대학교 2000 論文集 Vol.38 No.-

APS법을 이용하여 Inconel모재 위에 YSZ/NiCrAlY를 다층으로 용사한 열장벽 피막의 종합적인 기계적, 열적 고온물성을 비교 ·평가하였다. 이렇게 얻어진 결과를 바탕으로 가장 우수한 고온물성치를 지닌 열장벽 피막을 Inconel모재 위에 YSZ/NiCrAlY의 혼합비를 선형적, 비선형적으로 11층으로 용사하여 종합적인 기계적, 열적 고온물성을 평가하였다. 용사된 피막의 두께는 500∼600㎛ 범위였고, 기공도는 9∼14%내외였다. Inconel 모재 위에 선형적으로 적층한 피막이 열피로에 가장 우수한 저항성을 보였다. 고온산화시험과 열충격시험에서도 선형적으로 적층한 피막이 비선형적으로 적층한 피막보다 더 우수하였다. 접착강도는 concave형이 614kgf/cm2로 가장 컸으며 파단이 가장 많이 일어난 층은 90(YSZ) : 10(NiCrAlY)층이었다. 이상의 결과를 종합한 결과 Inconel모재 위에 선형적으로 적층한 TBC가 가장 우수한 고온 물성을 보유한 것으로 사료된다. The purpose of this study is to evaluate functional gradient thermal barrier coatings. The malt-layered TBC on Inconel substrate specimens were prepared by APS method. The evaluations of mechanical and thermal properties have been conducted. 11 layered TBC specimens were prepared by APS method in which the mixture ratio of YSZ/NiCrAlY is linear and non-linear. The range of thickness of coated layers was 500 ∼ 600㎛. The average porosity of coatings was 9.4%. The linear-type specimens showed best resistance for thermal fatigue. In the high temperature oxidation test and the thermal shock test, the linear types were better than the non-linear types. The bond strength of the concave type was greater than that of linear types and convex type coatings. The fracture of the coating layers was occurred in the 10th layer (90(Ceramic) : 10 (NiCrAlY)). According to the results of this research, TBC of 11 layer coatings of the linear type on Inconel substrate was the optimum coating.