• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.398-406
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• 2022

In order to increase the electrochemical performance of thermal battery anode, LIFT anode having the same weight but a larger lithium content in electrodes was fabricated by mixing lithium, iron and titanium. By applying these electrodes, a single cell and a thermal battery were prepared, and the effect of LIFT anode on electrochemical performance was evaluated. The LIFT-applied single cell presented a better cell performance than LIFe-applied single cell at 500℃ and 550℃. The discharge performance of LIFT-applied single cell, which included the operating time (787s), specific capacity (1,683 Asg^-1), and electrode utilization (80.7%), was improved collectively compared to the LIFe applied single cell (736s, 1,245 As g^-1, and 74.6%) at 500℃. As the discharge progressed, the internal resistance of LIFT anode decreased, because the lithium migration path was formed due to the presence of large titanium particles among iron particles. These results were analyzed in terms of the microstructure of electrode using SEM. Energy density of LIFT-applied single cell also increased by 10% to 142.1 Wh kg^-1 compared to that of LIFe-applied single cell (127.4 Wh kg^-1). In addition, the LIFT-applied single cell presented a stable discharge performance for 6,500s without a short circuit which could occur by molten lithium under an open circuit voltage condition with a high pressure (4 kgf cm^-2). As observed in the high temperature thermal battery performance tests, the voltage and specific capacity of LIFT-applied thermal battery are superior to those of LIFe-applied thermal batteries, indicating that the energy density of LIFT-applied thermal batteries should remarkably increase.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.251-251
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• 2017

전 세계적으로 기후변화 및 다양한 삶의 패턴이 변화되면서 예상되는 자원의 부족을 해결하기 위한 많은 노력이 진행되고 있다. 특히 범 국가적으로 지속가능한 자원안보 실현을 위한 적정 솔루션을 제공하고 자원의 연계에 따른 효율성과 효과성을 극대화하기 위해 물, 에너지, 식량의 연계를 통한 기술을 개발하고 적용하고 있으나, 아직까지 국가단위의 대규모 사례는 부족하며, Community Scale의 형태로 진행되고 있는 실정이다. 본 논문에서는 국내에서의 물, 에너지, 식량의 연계 기술을 도출하기 위해 국외에서 진행되고 있는 기술에 대한 현황과 효과를 분석하여 국내의 적용방안에 대해 분석하고자 한다. 국외의 사례로는 프랑스 전력공사(EDF)에서는 2000년 초반 기존의 규정대로 물공급을 지속하면 발전에 어려움이 발생하는 것을 인식하여, 주요 농업 관개시설과 물절약협약을 체결하고 물절약에 따른 금전적 보상대책을 마련하였다. 이를 통해 물 절약의 30%는 기존의 관행과 관리방식의 변화에 의해 이루어졌고, 약 70%는 효율적 물 사용기술을 통해 절감효과를 도출하였다. 또한 관개용수와 발전량의 효율적 물사용을 통해 3억2,500만$m^3$에서 2억3,500만$m^3$ 으로의 절감효과를 달성할 수 있었다. 오스틴 수도회사, 텍사스 가수 서비스, 오스틴 에너지 회사 등 텍사스의 3개회사가 상호 협약을 통해 다가구 에너지 및 물효율 프로그램을 개발하고 자원을 효율적으로 관리할 수 있는 주택을 개조하여, 연간 470만 kWh의 전기와 3,785만 리터의 물을 절약하고 있다. 베트남 Red강의 경우 베트남의 근대화 및 산업화를 위해 많은 물과 전기가 필요함에 따라 물사용량을 규제하였고 이로 인해 농작물 재배를 고려하여 장기적이고 다방면적인 전략을 도출하였다. 정유회사 CHEVRON에서는 미국 캘리포니아에서 오일 1배럴을 생산할 때마다 10배럴의 물을 생산하여 오일생산 과정에 이용하며 $182km^2$ 면적의 농장에 농업용수를 공급할 수 있었다. 특히, California 오일 추출과정에서 물과 오일을 분리하고 그 과정에서 발생한 물을 재이용하기 위하여 수처리과정을 통하여 매일 $2,650m^3$의 물 생산하게 되었다. 이러한 외국의 사례들을 바탕으로 하여 국내에서도 다양한 형태의 넥서스 기술을 접목하여 미래에 예측되는 자원 부족을 선제적으로 대응하는 방안을 수립할 때이다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.5 no.4
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• pp.281-287
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• 1976

Solar Radiation is effected by the astronomical condition, the collector inclination, the air and the climate conditions before it reaches an earth surface. Based on the data which have been collected and recorded by the Central Meteorological Office and other resources, the effects of those conditions in Korea are analysed and appraised in this report.

• Nuclear Engineering and Technology
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• v.20 no.3
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• pp.170-178
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• 1988

An automated ultrasonic flaw detection system was developed for thin-walled and short tubes such as Zircaloy-4 tubes used for cladding heavy-water reactor fuel. The system was based on the two channels immersion pulse-echo technique using 14 MHz shear wave and the specially developed helical scanning technique, in which the tube to be tested is only rotated and the small water tank with spherical focus ultrasonic transducers is translated along the tube length. The optimum angle of incidence of ultrasonic beam was 26 degrees, at which the inside and outside surface defects with the same size and direction could be detected with the same sensitivity. The maximum permissible defects in the Zircaloy-4 tubes, i.e., the longitudinal and circumferential v notches with the length of 0.76mm and 0.38mm, respectively and the depth of 0.04 mm on the inside and outside surface, could be easily detected by the system with the inspection speed of about 1 m/min and the very excellent reproducibility. The ratio of signal to noise was greater than 20 dB for the longitudinal defects and 12 dB for the circumferential defects.

• Journal of the Korean institute of surface engineering
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• v.54 no.3
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• pp.144-151
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• 2021

In the present work, planar-type ZnO powder of [0001] plane with a high aspect ratio range of 20:1 to 50:1 was synthesized. Ag or CuO could be coated on the planar-type ZnO powder by wet methods such as centrifugation or ball milling. During the coating, the average size of the powder was slightly increased while maintaining the shape and XRD pattern of ZnO. When Ag or CuO was coated, the absolute value of the zeta potential, as well as the concentration of oxygen vacancy, was increased. Ag or CuO coated planar-type ZnO power exhibited excellent antibacterial performance, which seems to be related to their high electrostatic attraction force. They could be made into a masterbatch by mixing with ABS resin, and their applicability to antibacterial substances was confirmed by manufacturing the caps of a keyboard.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.175-183
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• 2024

Geopolymer, also known as alkali aluminum silicate, is used as a substitute for Portland cement, and it is also used as a binder because of its good adhesive properties and heat resistance. Since Davidovits developed Geopolymer matrix composites (GMCs) based on the binder properties of geopolymer, they have been utilized as flame exhaust ducts and aircraft fire protection materials. Geopolymer structures are formed through hydrolysis and dehydration reactions, and their physical properties can be influenced by reaction conditions such as concentration, reaction time, and temperature. The aim of this study is to examine the effects of silica size and aging time on the mechanical properties of composites. Commercial water glass and kaolin were used to synthesize geopolymers, and two types of silica powder were added to increase the silicon content. Using carbon fiber mats, a fiber-reinforced composite material was fabricated using the hand lay-up method. Spectroscopy was used to confirm polymerization, aging effects, and heat treatment, and composite materials were used to measure flexural strength. As a result, it was confirmed that the longer time aging and use of nano-sized silica particles were helpful in improving the mechanical properties of the geopolymer matrix composite.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.140-145
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• 2024

High temperature co-electrolysis of H₂O-CO₂ mixtures using solid oxide cells has attracted attention as promising CO₂ utilization technology for production of syngas (H₂/CO), feedstock for E-fuel synthesis. For direct supply to E-fuel production such as hydrocarbon and methanol, the outlet gas ratio (H₂/CO/CO₂) of co-electrolysis should be controlled. In this work, current voltage characteristic test and product gas analysis were carried out under various reaction conditions which could attain proper syngas ratio.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.162-167
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• 2024

Fossil fuels have been main energy source to people. However, enormous amount of CO₂ was emitted over the world , resulting in global climate crisis today. Recently, solid oxide electrolyzer cell (SOEC) is getting attention as an effective way for producing H₂, a clean energy resource for the future. Also, SOEC could be applicable to reverse water-gas shift reaction process due to its high-temperature operating condition. Here, SOEC system was utilized for both H₂ production and CO₂ reduction process, allowing product gas composition change by controlling operating conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.351-357
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• 1983

To study the relationships between soybean seed yield and meteorological elements, the investigation into the important agronomic characters of Bongeui cultivar and climatic factors such as precipitation, rainy days, and temperature from 1970 to 1981 was made. The results obtained were summarized as follows: 1) Coefficients of variabilities for pod-filling rate, seed yield, number of pods per plant, and seed weight were about 38%, 30%, 30%, and 5.5%, respectively. 2) Weather conditions mainly in July and August influenced soybean production. Particularly, high temperature played an important role in soybean yield reduction. 3) Correlation coefficients between maximum, minimum, or average temperature of July (and, in the case of August, maximum temperature only) and yield or seed weight, and between those of August and podfilling rate were significantly negative. 4) Regression equations between average temperature of July or maximum temperature of August and yield were Y=-42.46X +1200.86 and Y=-37.95X + 1210.42, respectively. 5) High temperature during the flowering stage affected soybean seed yield reduction significantly.

• Korea Petroleum Association Journal
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• no.3 s.181
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• pp.88-107
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• 1996

이 자료는 오는 3월말 특정석유제품수입잠정조치법 폐지를 앞두고 일본경제연구소가 마련한 연구자료중 발췌 전재한 것이다. <편집자 주>