• Title/Summary/Keyword: commercial power

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Structural and Electrochemical characterization of LiCoO2 Nano Cathode Powder Fabricated by Mechanochemical Process (기계 화학법에 의해 제작된 나노 LiCoO2 양극 분말의 구조 및 전기화학적 특성)

  • Choi, Sun-Hee;Kim, Joo-Sun;Yoon, Young-Soo
    • Journal of the Korean Ceramic Society
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    • v.41 no.1
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    • pp.86-91
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    • 2004
  • $LiCoO_2$ cathode powders with round particle shaped and nano grain sized of 70-300nm were synthesized by a mechanochemical method. The surface of Li-Co precursor prepared by freeze drying method was modified by $K_2SO_4$ coating and ball milling was used for the coating process. The precursor was crystallized to high temperature form of $LiCoO_2$ at $800^{\circ}C$ and the grain growth was inhibited by the $K_2SO_4$ coating effect. The $K_2SO_4$ coating was not decomposed at $800^{\circ}C$ and prevented the contact in the Li-Co precursor particles. The nano-sized $LiCoO_2$ powder had tetragonal phase and it affected the Li diffusion through the surface of particles. It means that the anode materials for hight performance battery should be satisfied not only small particle size but phase contol on the surface of particles. In this study, the powder characteristics and rate capabilities were compared with a commercial powder and the nano-sized $LiCoO_2$ powder fabricated by the mechanochemical method. And the crucial factor which affects on battery performance was also examined.

A Study on the MDAS-DR Antenna for Shaping Flat-Topped Radiation Pattern (구형 빔 패턴 형성을 위한 MDAS-DR 안테나에 대한 연구)

  • Eom, Soon-Young;Yun, Je-Hoon;Jeon, Soon-Ick;Kim, Chang-Joo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.3 s.118
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    • pp.323-333
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    • 2007
  • In this paper, a new MDAS-DR antenna structure designed to efficiently shape a flat-topped radiation pattern is proposed. The antenna structure is composed of a stacked micro-strip patch exciter and a multi-layered disk array structure(MDAS) surrounded by a dielectric ring. The MDAS, which was supplied by a stacked microstrip patch exciter with radiating power, can form a flat-topped radiation pattern in a far field by a mutual interaction with the surrounding dielectric ring. Therefore, the design parameters of the dielectric ring and the MDAS structure are important design parameters for shaping a flat-topped radiation pattern. The proposed antenna used twelve multi-layered disk array elements and a Teflon material with a dielectric constant of 2.05. An antenna operated at 10 GHz$(9.6\sim10.4\;GHz)$ was designed in order to verify the effectiveness of the proposed antenna structure. The commercial simulator of CST Microwave $Studio^{TM}$, which was adapted to a 3-D antenna structure analysis, was used for the simulation. The antenna breadboard was also fabricated and its electrical performance was measured in an anechoic antenna chamber. The measured results of the antenna breadboard with a flat-topped radiation pattern were found to be in good agreement with the simulated one. The MDAS-DR antenna gain measured at 10 GHz was 11.18 dBi, and the MDAS-DR antenna was capable of shaping a good flat-topped radiation pattern with a beam-width of about $40^{\circ}$, at least within a fractional bandwidth of 8.0 %.

A Numerical Modeling of the Temperature Dependence on Electrochemical Properties for Solid Oxide Electrolysis Cell(SOEC) (고체 산화물 수전해 시스템(SOEC)에서 전기화학적 특성의 온도 의존성에 대한 수치 모델링)

  • Han, Kyoung Ho;Jung, Jung Yul;Yoon, Do Young
    • Journal of Energy Engineering
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    • v.29 no.2
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    • pp.1-9
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    • 2020
  • In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La0.9Sr0.1MnO3) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

The Impact of Clothings of Kisaengs in the later Choson (조선후기의 기녀 복식이 사회에 미친 영향)

  • Kim, Hye-Young
    • The Journal of Natural Sciences
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    • v.8 no.2
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    • pp.289-321
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    • 1996
  • After the two big wars (Imjin Woeran and Byungia Horan), the Lee Dynasty confronted rapid transitional periods in almost all aspects of the society. Corruption of the governmental system by the wars and disordered social structures also caused confusion in the social position system. In addition, development of the commercial economic system and monetary economy brought up a new rich middle-class, "Joong in Gyegeup". In ideological aspects, Confucianism indulged in and stick to isms and ics, and the Confucian morality slackened, thus a more pragmatic ideology, "Silhak Sasang", developed. And the emergence of the modern literature and art of the 'common people' was followed by the appearance of the common-people class including those having the common-people concept among the noble-class "Yangban Gyegeup". This evoked a new common costume culture and the fashion appeared. The public could no longer find the power and appeal from the preexisting ruling classes due to the changed role and sense of value. Thus, they sought a new symbolic leader group that would to be the new standard of the newly changed society. That was a group of people called as "Kisaeng" liberal and independent. They were performing social activities, enjoying poetry, music and dancing, and classy dressers, having physically attractive bodies. The erotic as well as luxurious mode proposed by them reflected the trend of that time. It concurred well with the concept and taste of the public, so it was accepted with a good response. That is, by following these leaders, the public achieved their identification and tried to share the prestige of the leaders. For this reason, the Kisaeng group attracted the public attention and led the taste of the public, thereby becoming the influential fashion leaders of that age.

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Effects of Medicinal Plants on the Quality and Physiological Functionalities of Traditional Ginseng Wine (각종 약용 식물 첨가가 전통 인삼주의 품질 특성과 생리기능성에 미치는 영향)

  • Lee, Eun-Na;Lee, Dae-Hyoung;Kim, Sin-Bum;Lee, Seung-Whan;Kim, Na-Mi;Lee, Jong-Soo
    • Journal of Ginseng Research
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    • v.31 no.2
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    • pp.102-108
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    • 2007
  • The goal of this study was to develop a highly valuable Korean traditional ginseng wine containing various bioactive compounds with good acceptability. The effect of some medicinal plants on the quality and physiological functionality of Korean traditional ginseng wine were investigated. Advanced traditional ginseng wine (AG wine) prepared by addition of 0.5% each Pleuropterus multflorus and Pueraria lobata into the rice mash containing 1% ginseng, 0.4% Fermivin(commercial alcohol fermentation yeast) and Koji (2:1 mixture of nuruk and amylase containing 36 Saccharogenic power per g) showed the highest acceptability and ethanol content (16.8%). Changes of functionalities of the AG wine during fermentation at $25^{\circ}C$ for 30 days were investigated. The highest antihypertensive angiotensin I-converting enzyme inhibitory activity (78.9%) and total acceptability of the AG wine were shown after fermentation at $25^{\circ}C$ for 20 days. However, antioxidant activity, SOD-like activity and fibrinolytic activity of the AG wines were not detected or very low. HMG-CoA reductase inhibitory activity of the AG wine was also shown to be 8.2% and 9.2% after fermentation for 15 days and 20 days, respectively.

A Design of Novel Instrumentation Amplifier Using a Fully-Differential Linear OTA (완전-차동 선형 OTA를 사용한 새로운 계측 증폭기 설계)

  • Cha, Hyeong-Woo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.1
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    • pp.59-67
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    • 2016
  • A novel instrumentation amplifier (IA) using fully-differential linear operational transconductance amplifier (FLOTA) for electronic measurement systems with low cost, wideband, and gain control with wide range is designed. The IA consists of a FLOTA, two resistor, and an operational amplifier(op-amp). The principal of the operating is that the difference of two input voltages applied into FLOTA converts into two same difference currents, and then these current drive resistor of (+) terminal and feedback resistor of op-amp to obtain output voltage. To verify operating principal of the IA, we designed the FLOTA and realized the IA used commercial op-amp LF356. Simulation results show that the FLOTA has linearity error of 0.1% and offset current of 2.1uA at input dynamic range ${\pm}3.0V$. The IA had wide gain range from -20dB to 60dB by variation of only one resistor and -3dB frequency for the 60dB was 10MHz. The proposed IA also has merits without matching of external resistor and controllable offset voltage using the other resistor. The power dissipation of the IA is 105mW at supply voltage of ${\pm}5V$.

[ $8{\sim}10.9$ ]-GHz-Band New LC Oscillator with Low Phase-Noise and Wide Tuning Range for SONET communication (SONET 통신 시스템을 위한 $8{\sim}10.9$ GHz 저 위상 잡음과 넓은 튜닝 범위를 갖는 새로운 구조의 LC VCO 설계)

  • Kim, Seung-Hoon;Cho, Hyo-Moon;Cho, Sang-Bock
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.1
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    • pp.50-55
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    • 2008
  • In this paper, New LC VCO with $8{\sim}10.9$ GHz Band has been designed using commercial $0.35-{\mu}m$ CMOS technology. This proposed circuit is consisted of the parallel construction of the typical NMOS and PMOS cross-coupled pair which is based on the LC tank, MOS cross-coupled pair which has same tail current of complementary NMOS and PMOS, and output buffer. The designed LC VCO, which is according to proposed structure in this paper, takes a 29% improvement of the wide tuning range as 8 GHz to 10.9 GHz, and a 6.48mW of low power dissipation. Its core size is $270{\mu}m{\times}340{\mu}m$ and its phase noise is as -117dBc Hz and -137dBc Hz at 1-MHz and 10-MHz offset, respectively. FOM of the new proposed LC VCO gets -189dBc/Hz at a 1-MHz offset from a 10GHz center frequency. This design is very useful for the 10Gb/s clock generator and data recovery integrated circuit(IC) and SONET communication applications.

Expansion of Coffee Plantation and Institutionalization of Customary Land Ownership - Case study of Dak Lak Province in Vietnam (베트남 중부고원지대 커피재배지역의 확대와 토지소유관행의 제도화: 닥락성(省)을 사례로)

  • Kim, Doo-Chul;Truong, Quang Hoang;Joh, Young Kug
    • Journal of the Economic Geographical Society of Korea
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    • v.19 no.2
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    • pp.378-398
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    • 2016
  • This paper aims to clarify the process of institutionalization of customary land ownership along with the expansion of coffee plantation in Dak Lak Province, Vietnam. Vietnam is the second-largest coffee exporter in the world. Most of the coffee areas are concentrated in Dak Lak-a province of commercial agricultural production. The expansion of coffee plantation in Dak Lak have brought a severe competition of land resources, and resulted in the transition of land ownership scheme from customary commons by ethnic minorities to those of exculsive private assets which is secured by the state. Institutionalization of customary land ownership in Dak Lak, however, was differently happened according to the geography from the center of state power as well as the value of land resources. In this paper, the authors argue that institutionalization of customary land ownership in Dak Lak was a result of compromising between statemaking process in the frontiers and "everyday resistance" of ethnic minorities, comparing 3 geographically different ethnic minorities' communities.

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ATPDraw Simulation for Transient Phenomena Analysis of Electrical Shock Underwater (수중 전격 과도현상 해석을 위한 ATPDraw 시뮬레이션)

  • Jung, Jong-Wook;Jung, Jin-Soo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.6
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    • pp.48-54
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    • 2007
  • This paper describes the analysis of transient phenomena on the point that a human body suffers an electrical shock. A couple of case studies were discussed by using an ATPDraw simulation tool. Two models for the case studies were constructed on the assumption that the electrical shock event takes place under water to simulate the severest condition ; the first model that the human body contacts with an energized part exposed to water ; the second model that both hands and feet simultaneously contact with the ground under water. After modeling, the transient phenomena for the models were analyzed by comparing the voltages and currents calculated at each part of the human body. As a result steep front kicks in voltage and current were observed as transient phenomena on the point that the human body contacts with the energized part exposed to water in the first model and the magnitudes of the kicks considerably increased. It was considered however, the effect of the kicks due to the commercial power source on the human body could be neglected because the product of the current through the body and the short duration is less than the safety limit. When both hands and feet simultaneously contact with the ground in the second model, the voltage generally decreased all over the body parts, while the current flowing through the chest abruptly increased. The duration of this current was very shot, as well, thus its effect on the electrical shock is considered insignificant. After all, it was confirmed through the simulation results that the electrical shock depends on the magnitude in voltage and the body impedance.

Effects of the addition of Hizikia fusiforme, Capsosiphon fulvescens, and Undaria pinnatifida sporophyll on antioxidant and inhibitory potential against enzymes related to type 2 diabetes of vegetable extract (혼합야채추출물의 항산화 및 항당뇨 효과 증진을 위한 톳, 매생이, 미역귀의 첨가효과)

  • Tong, Tao;Zhang, Chengmei;Ko, Du-Ok;Kim, Sup-Bo;Jung, Kwang-Jin;Kang, Seong-Gook
    • Food Science and Preservation
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    • v.21 no.4
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    • pp.460-467
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    • 2014
  • This study was conducted to investigate the effect of the addition of Hizikia fusiforme, Capsosiphon fulvescens, and Undaria pinnatifida sporophyll on the antioxidant and inhibitory potentials against key enzymes related to type 2 diabetes of a commercial vegetable extract. The nutritional quality and mineral concentration of a vegetable extract with seaweeds added were also analyzed. The addition levels of seaweed did not influence the proximate composition, whereas the calcium, sodium, potassium, magnesium, and iron concentrations significantly increased at the 5% Hizikia fusiforme and Undaria pinnatifida sporophyll addition levels. The 20% Hizikia fusiforme addition level significantly increased the total phenolic content and reducing power by 47.08% and 16.82%. The hydroxyl radical scavenging ability of the vegetable extract was not strengthened with the addition of seaweeds. The DPPH radical scavenging activity at the 20% Hizikia fusiforme, Capsosiphon fulvescens, and Undaria pinnatifida sporophyll addition levels significantly increased by 27.47%, 22.25%, and 17.27%, respectively. The vegetable extract with seaweeds added showed higher-level ${\alpha}$-glucosidase inhibition activities, accompanied by relatively weaker ${\alpha}$-amylase inhibition activity. In particular, at the 5% Undaria pinnatifida sporophyll addition level, the ${\alpha}$-glucosidase activity was significantly inhibited by 98.26%. Overall, the results showed that the incorporation of seaweeds into a vegetable extract effectively increased the mineral concentration and improved the antioxidant and inhibitory abilities of the extract on key enzymes linked to type 2 diabetes.