• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.88-95
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• 2014

Spinning process to inner wall has been applied for reducing the weight of regenerative cooling chamber of liquid propellent rocket engine. The fractures of the blanks of cylinder part and nozzle throat part have been observed during spinning processes. In order to overcome the problem, the mandrel and the blank shape have been modified, and the inner wall was successfully manufactured through the modifications. The manufactured spinning prototype of nozzle throat part was successfully bulged without cracking and necking, and it was confirmed to secure sufficient formability necessary for fabricating thrust chamber.

• International Journal of Reliability and Applications
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• v.8 no.2
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• pp.153-173
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• 2007

Wood-plastic composites (WPC) are gaining market share in the building industry because of durability/maintenance advantages of WPC over traditional wood products and because of the removal of chromated copper arsenate (CCA) pressure-treated wood from the market. In order to ensure continued market share growth, WPC manufacturers need greater focus on reliability, quality, and cost. The reliability methods outlined in this paper can be used to improve the quality of WPC and lower manufacturing costs by reducing raw material inputs and minimizing WPC waste. Statistical methods are described for analyzing stiffness (tangent modulus of elasticity: MOE) and flexural strength (modulus of rupture: MOR) test results on sampled WPC panels. Descriptive statistics, graphs, and reliability plots from these test data are presented and interpreted. Sources of variability in the MOE and MOR of WPC are suggested. The methods outlined may directly benefit WPC manufacturers through a better understanding of strength and stiffness measures, which can lead to process improvements and, ultimately, a superior WPC product with improved reliability, thereby creating greater customer satisfaction.

• Journal of Powder Materials
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• v.8 no.4
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• pp.245-252
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• 2001

Recent remarkable progress in the semiconductor industry has promoted smaller size of semiconductor chips and increased amounts of heat generation. So, the demand for a substrate material to meet both the characteristics of thermal expansion coefficient and heat radiation has been on the increase. Under such conditions, tungsten(W)-copper(Cu) has been proposed as materials to meet both of the above characteristics. In the present study, the W-10wt.%Cu powders were synthesised by the mixing and hydrogen reduction of the starting mixture materials such as W-Cu, $W-CuCl_2$and $WO_3-CuCl_2$ in order to obtain the full densification. The W-10wt.%Cu produced by hydrogen reduction showed the higher interparticle friction than the simple mixed W-10wt%Cu because of the W agglomerates. In the dilatometric analysis the W-10wt.%Cu prepared from the $W-CuCl_2$was largely shrank by heating up $1400^{\circ}C$ at the constant heating rate of $5^{\circ}C$/min. The possibility of application of metal injection molding (MIM) was also investigated for mass production of the complex shaped W-Cu parts in semiconductor devices. The relationship between the temperature of molding die and the pressure of injection molding was analyzed and the heating up stage of 120-$290^{\circ}C$ in the debinding process was controlled for the most suitable MIM condition.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.142-143
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• 2007

A 1MW class HTS(High-Temperature Superconducting) synchronous motor has been developed. This motor is aimed to be utilized for industrial application such as large motors operating in large plants. The HTS field coil of the developed motor is cooled by way of Neon thermosiphon mechanism and the stator coil is cooled by water through hollow copper conductor. This paper describes performance test results of our motor, which was conducted at steady state in generator mode and motor mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.545-545
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• 2007

Recently, innovative process has been investigated in order to replace the conventional high-cost micro patterning processes on the electronic products. To produce desirable profit margins from this low cost products, printed circuit board(PCB), will require dramatic changes in the current manufacturing philosophies and processes. Innovative process using metal nano particles replaces the current industry standard of subtractive etched of copper as a highly efficient way to produce robust circuitry on low cost substrates. An advantage of using metal nano particles process in patterned conductive line manufacturing is that the process is additive. Material is only deposited in desired locations, thereby reducing the amount of chemical and material waste. Simply, it just draws on the substrate as glass epoxy or polyimide with metal nano particles. Particles, when their size becomes nano-meter scale, show some specific characteristics such as enhanced reactivity of surface atoms, decrease in melting point, high electric conductivity compared with the bulk. Melting temperature of metal gets low, the metal nano particles could be formated onto polymer substrates and sintered under $300^{\circ}C$, which would be applied in PCB. It can be getting the metal line of excellent electric conductivity.

• Journal of the Korean Wood Science and Technology
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• v.43 no.2
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• pp.265-273
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• 2015

In general, when wood products are used outdoors for a certain period of time the surface color of wood changes due to light, water, heat and so on. This color change can be considered importantly for the product's market value. In this study, the color change of ACQ (Alkaline Copper Quaternary) and CBHDO (CuO $H_3BO_3$ N-cyclohexyldiazenium-anion) treated wood and untreated wood was investigated during 2-year weathering test. From this experimental study, it was found that the colors of the treated wood changed more reddish and yellowish from green. Meanwhile, the untreated wood turned to grey color rapidly. Also, the color of the treated wood in short-term exposure changed closer to the inherent color of the fresh natural wood than that of the untreated woods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.209-223
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• 2019

This study was conducted to investigate nutrition characteristics of the following major commercially available dried fish (MCDF) in South Korea: plain-dried fish [nogari (PD-N), Alaska pollock (PD-AP), red tongue sole (PD-RTS), and young tidepool gunnel (PD-YTG)], salt-dried fish [(yellow corvina (SD-YC) and red tilefish (SD-RT)], four types of boiled-dried anchovy of different sizes (BD-As), and freeze-dried fish [Pacific saury (FD-PS), Alaska pollock (FD-AP), and Katsuobushi]. The energy content of the MCDF ranged from 103.0 to 420.5 kcal per 100 g. The MCDF in nutritional and functional properties of minerals were SD-RT and Katsuobushi in calcium; none in phosphorus, sodium, or zinc; Katsuobushi in potassium and magnesium; PD-AP, SD-YC, and SD-RT in iron, PD-AP, PD-RTS, SD-YC, and SD-RT in copper; and PD-N, PD-AP, PD-RTS, SD-YC, SD-RT, FD-PS, FD-AP and Katsuobushi in manganese. The total amino acid content of the MCDF ranged from 15.85 to 71.96 g per 100 g; the major amino acids were glutamic acid, aspartic acid, lysine, and leucine. The fatty acid content of the MCDF ranged from 0.81 to 2.93 g per 100 g. The MCFSP expected in nutritional and functional properties of vitamins were PD-N, PD-RTS, FD-PS, FD-AP, and Katsuobushi in riboflavin; PD-N, PD-AP, PD-YTG, BD-As, FD-PS, FD-AP, and Katsuobushi in niacin; PD-N, PD-RTS, SD-YC, and BD-As in vitamin A; and PD-AP, PD-YTG, SD-YC, and FD-AP in vitamin E.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.1-12
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• 2019

We investigated the nutritional components of the major commercial frozen seafood products (MCFSP) [sliced frozen-skipjack tuna (ST), -bigeye tuna (BET), -bluefin tuna (BFT), -yellowfin tuna (YT), fish steaks (FST), fish pancakes (FP), fish cutlets (FC), seafood cake balls (SCB), fried shrimp (FS), shrimp patties (SP), shrimp cutlets (SC)] in Korea. All species of sliced frozen tuna and FST were classified as low-calorie foods; the other frozen seafood products were classified as medium-calorie foods. The MCFSP were significant sources of nutritional and functional minerals: the SCB and SC provided calcium; the FST, FC, and SCB provided phosphorus; the BET, YT, and FST provided potassium; the FST, FC, and BFT provided magnesium; the FST, FP and SC provided iron; the SCB, FS, SP, and SC provided zinc; the YT and SCB provided copper; and the FC provided manganese. The total amino acid contents of the MCFSP were in the range of 6.85-26.34 g/100 g. Glutamic acid was the major amino acid in the SCB, FS, SP, and SC. Fatty acid contents were in the range of 386-2,925 mg/100 g; the major fatty acids in the ST, BFT and YT were 16:0, 18:1n-9, 22:6n-3. The MCFSP were not a significant source of vitamin A or riboflavin.

• Journal of Environmental Science International
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• v.19 no.8
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• pp.951-960
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• 2010

Sediment works as a resource for electric cells. This paper was designed in order to verify how sediment cells work with anodic material such as metal and carbon fiber. As known quite well, sediment under sea, rivers or streams provides a furbished environment for generating electrons via some electron transfer mechanism within specific microbial population or corrosive oxidation on the metal surfaces in the presence of oxygen or water molecules. We experimented with one type of sediment cell using different anodic material so as to attain prolonged, maximum electric power. Iron, Zinc, aluminum, copper, zinc/copper, and graphite felt were tested for anodes. Also, combined type of anodes-metal embedded in the graphite fiber matrix-was experimented for better performances. The results show that the combined type of anodes exhibited sustainable electricity production for ca. 600 h with max. $0.57\;W/m^2$ Al/Graphite. Meanwhile, graphite-only electrodes produced max. $0.11\;W/m^2$ along with quite stationary electric output, and for a zinc electrode, in which the electricity generated was not stable with time, therefore resulting in relatively sharp drop in that after 100 h or so, the maximum power density was $0.64\;W/m^2$. It was observed that the corrosive reaction rates in the metal electrodes might be varied, so that strength and stability in the electric performances(voltage and current density) could be affected by them. In addition to that, COD(chemical oxygen demand) of the sediment of the cell system was reduced by 17.5~36.7% in 600 h, which implied that the organic matter in the sediment would be partially converted into non-COD substances, that is, would suggest a way for decontamination of the aged, anaerobic sediment as well. The pH reduction for all electrodes could be a sign of organic acid production due to complicated chemical changes in the sediment.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.221-228
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• 1992

In order to evaluate the degree of air pollution, soils from 125 and 60points of main streets of Seoul and Daejeon, respectively, were sampled and analyzed for the contents of lead, copper, iron and zinc by nitric acid($HNO_3$) extraction followed by atomic absorption spectrophotometry during June and September, 1990. The Pb contents of Seoul and Daejeon were 350.2$\mu$g/g and 175.9$\mu$g/g, respectively, which were 14.5times and 7.3times respectively higher than the control(24.0). In Seoul, the commercial area gave the highest value followed by resdential and industrial areas in the decreasing order, while the order in Daejeon was Industrial, commercial and residential areas. The Cu contents in Seoul and Daejeon were very similar(236.6 and 234.6, respectively) each other, and about 11times higher than the control(20.9). The concentration was highest in industrial, followed by commercial and the lowest in residential areas in Seoul, while the order in Daejeon was industrial, residential and commercial areas. The Fe contents were 25716.5 in Seoul and 22838.6 in Daejeon, both being similar to the control value(22537.0). The value was highest in industrial and next in commercial areas and the lowest in residential area both in Seoul and Daejeon. The Zn contents in Seoul and Daejeon were 728.2 and 404.0, respectively, wihch were 6.3 and 3.6times higher than the control(113.3). The value was highest in commercial and next in industrial areas and the lowest in residental area in Seoul, while the order was industrial, residential and commercial areas in Daejeon. The heavy metal content was higher in the soil of main streets than that of minor streets in Seoul. The content of lead in Seoul was higher in the streets of Chongro-ku(525.9) and Chung-ku(684.8), the central area of the city which had a heavy traffic, than those in Nowon-ku(320.3) and Kwanak-ku(312.6) which had relatively less traffic crowd. The similar pattern was observed in the content of zinc; it was higher in Chongro-ku(1305.0) and Chung-ku(1335.4) than in Nowon-ku(489.1) and Kwanak-ku(569.8). In Daejeon, the contents of lead and zinc were decreasing as the distance from Daejeon Railroad Station increased : they were respectively 157.8 and 447.7 within 2km from the station, 157.6 and 235.7 with in 2-4km, and 63.5 and 156.2 within 4-6km and 58.7 and 142.2 within 6-8km. In summary, the contents of lead, copper and zinc were generally higher in the central area of the city, areas of heavy traffic and areas of industry and commerce.