• Corrosion Science and Technology
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• v.12 no.1
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• pp.12-26
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• 2013

This work focused on galvanic corrosion of carbon steel bolted GECM/Al plates by long-term test in tap water and NaCl solutions. Test product was carbon steel bolted between cross packed GECM and painted aluminium. Tests for the product and coupled parts determined corrosion rate in tap water and NaCl solutions. Also, using a potentiostat and salt water sprayer, galvanic test was done. In galvanic test on carbon steel bolted GECM/Al plates, corrosion of carbon steel bolt was faster in series of tap water>1% NaCl solution>3.5% NaCl solution. In galvanic couple between aluminium and carbon steel bolt, their corrosion rates were higher than those of single specimen. In galvanic couple between GECM, aluminium, and carbon steel bolt, corrosion behaviors of carbon steel bolt and aluminium were changed due to different corrosion mechanism in tap water and chloride solution.

• Journal of Hydrogen and New Energy
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• v.8 no.4
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• pp.161-171
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• 1997

$AB_2$ type Zr-based Laves phase alloys have been studied for potential application as negative electrode in Ni/MH batteries. However, They have a serious disadvantage of poor activation behavior in KOH solution. In this work, a new method of alloy design method was tried for improving Zr-based alloy activation. this method has focused on phase controlling to make multi-phase microstructure. In the case of multi-phase Zr-V-Mn-Ni shows good performance in activation, but activation mechanism has not been known. So, we were in search of elucidating this mechanism, Using morphological and electrochemical analysis, we could find that surface morphology and electocatalytic activity of the alloy change during immersion in KOH solution. V-rich second phases are selectively corroded and dissolved and then become Ni-rich phases. Resulting from these surface reaction in KOH solution, self-hydrogen charging occurs through Ni-rich phase. However, the alloy has poor cyclic durability because of such a corrosion mechanism. Therefore, finally we developed durable alloys by substitution of other alloying element.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.1
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• pp.23-27
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• 2014

Nutrient accumulation in surface soil has become a serious problem for cucumber production in greenhouse. However, still in many cases, soil management practices are only focused on maintaining crop yield, regardless of sustainability related with soil chemical properties. This study was conducted to propose a sustainable soil management practice by investigating the impact of cover crop species and nitrogen rate of fertigated solution on cucumber yield and soil chemical properties in greenhouse condition. Rye and hairy vetch were tested as a fallow cover crop, and each amount of urea (1/2, 3/4, 1 times of N fertilizer recommendations), determined by soil testing result, was supplied in fertigation plots as an additional nitrogen source. The result showed that the yield of cucumber was higher in rye treatment than control and hairy vetch treatment. In addition, rye effectively reduced EC and accumulated nutrients from the soil. Meanwhile, N concentration of fertigated solution showed no significant effect on the growth and yield of cucumber. Consequently, these results suggest that it is desirable to choose rye as a fallow catch crop for sustainable cucumber production in greenhouse.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.362-373
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• 2020

The purpose of this study is to verify the possibility of applying sports psychological training based on a solution-based short-term counseling approach. the study subject was a total of 8 units as one of the national athletes of Vietthlon. the measurement tools consisted of questionnaires and in-depth consultations, and the pre- and post-changes were measured and compared based on the results of the winter sports competitions. The results of the study showed that the negative thinking of the athletes was reasonable and positive change. Within a short period of time, confidence and competence in performance were improved, and cognitive anxiety was greatly reduced.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.286-294
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• 2017

The events at the Fukushima Daiichi Nuclear Power Station in March 2011 point out, among other matters, that concurrent accidents at multiple units of a site can occur in reality. Although site risk has been deterministically considered to some extent in nuclear power plant siting and design, potential occurrence of multi-unit accident sequences at a site was not investigated in sufficient detail thus far in the nuclear power community. Therefore, there is considerable worldwide interest and research effort directed toward multi-unit site risk assessment, especially in the countries with high-density nuclear-power-plant sites such as Korea. As the technique of probabilistic safety assessment (PSA) has been successfully applied to evaluate the risk associated with operation of nuclear power plants in the past several decades, the PSA having primarily focused on single-unit risks is now being extended to the multi-unit PSA. In this paper we first characterize the site risk with explicit consideration of the risk associated with spent fuel pools as well as the reactor risks. The status of multi-unit risk assessment is discussed next, followed by a description of the emerging issues relevant to the multi-unit risk evaluation from a practical standpoint.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.792-799
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• 1998

Further improvement of existing $H_{2}O/LiBr$ absorption refrigeration machine is absolutely neces-sary to promote the utilization of gas-cooling system Among various methods to improve the per-formance of the absorption refrigeration machine this research has focused on the use of a new working fluid that has better properties than the existing $H_{2}O/LiBr$ working fluid. In the series of the research, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ system was selected as the most promisable candidate. The absorption refrigeration machine is water-cooled double-effect, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ sys-tem with series flow type. In this study we found out the characteristic of new working solution through the cycle simulation and compared the result with that of LiBr solution to evaluate. Theoptimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance. Results demonstrate that new working fluid subsrantially increases COP by as much as 10% and has a wider working range with 8% higher crystallization limits compared to the conventional $H_{2}O/LiBr$.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.16-21
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• 2010

This research focused on the spray and distribution characteristics of urea solution by applying flow visualization techniques and did durability and driver test on injectors as well. The spray characteristics of urea solution was observed by CCD camera. Also, the distribution characteristics of urea solution was evaluated quantitatively as well by using 3D laser scanner equipment. It was considered that it was reasonable to use the injector for gasoline engine in order to inject the urea. The best distribution chart result was observed near 45cm distance difference between catalyst and urea spray injector. As a result of trapped urea distribution chart analysis, optimal pressure and volumetric flow rates of air and urea were derived in order to improve the distribution of Urea. This information may contribute to provide fundamental data in the future.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.245-250
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• 2006

This study was focused on the use of cationic PAM (Polyacrylamide) as a surface sizing additive to improve the surface sizing properties of paper. Effects of the ionic property, viscosity and charge density of PAM on bending stiffness of surface sized papers were investigated. Use of cationic PAM as a surface sizing additive improved bending stiffness while addition of anionic PAM did not show any effect. Increase of starch holdout with the addition of cationic PAM was attributed as a prime reason of stiffness increase. Viscosity of PAM was one of the most important factors affecting surface sizing due to its influence on the interaction between cationic PAM and oxidized starch solution. Greater improvement of bending stiffness of paper was obtained when high charged PAM was used as an additive. The order of addition was found to have significant influence on the effect of additives since it influences the formation of network structure among starch, cationic PAM, and SA (styrene acrylic acid copolymer). Investigation on the penetration of starch solution was carried out with CLSM (Confocal Laser Scanning Microscopy), and it was shown that the addition of cationic PAM to oxidized starch solution made starch molecules stay on the paper surface rather than penetrating into the paper structure because of the electrostatic interaction between negatively charged fibers and positively charged cationic PAM.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.84-88
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• 2013

These days embedded technology may be the most significant development in the electronics industry. The study focused on the development of active device embedding using flexible printed circuit in view of process and materials. The authors fabricated 30um thickness Si chip without any crack, chipping defects with a dicing before grinding process. In order to embed chips into flexible PCB, the chip pads on a chip are connected to bonding pad on flexible PCB using an ACF film. After packaging, all sample were tested by the O/S test and carried out the reliability test. All samples passed environmental reliability test. In the future, this technology will be applied to the wearable electronics and flexible display in the variety of electronics product.

• Korean Management Science Review
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• v.33 no.1
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• pp.101-117
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• 2016

In 2000s, incidence of natural disaster is increasing continuously. Therefore, the necessity of research on the effective disaster response is emphasized. Korea is not safe from natural disaster. Natural disasters like torrential downpours, typhoons have occurred more frequently than before. In addition disasters like droughts and MERS has also occurred. Therefore, needs for effective systems and algorithms to respond disaster are increased. This study covers the vehicle routing problem for effective logistics in disaster situations caused by natural disasters. The emergency vehicle route problem has different property from the general vehicle route problem. It has the property of the importance of deadline, the uncertain and dynamic demand information, and the uncertainty in information transfer. In this study, a solution that focused on the importance of deadline. In this study, the heuristic solution using the genetic algorithm are suggested. Finally the simulation experiment which reflects the actual environment are conducted to verify the performance of the solution.