• Journal of the Korea Academia-Industrial cooperation Society
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• 제20권6호
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• pp.74-79
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• 2019

The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.

• Korean Journal of Family Social Work
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• 제57호
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• pp.159-182
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• 2017

With using the 4th and 5th wave of KLoSA(Korean Longitudinal Study of Aging), this study analyzed the effect of the factors of Rowe and Kahn's successful aging model on the life satisfaction of older adults. The target population of this study was 1,385 who is older than 65. As data analysis, hierarchical multiple regression was used. The variables such as demographics, avoiding diseases and disability, high cognitive and physical function and engagement with life, relationship with adult children were entered hierarchically for the regression analysis. Since there are differences of longevity by gender, the difference of factors of successful aging were compared by marital status. In this study (besides Rowe and Kahn's successful aging model such as avoiding disease and disability, high cognitive and physical function, and engagement with life), the relationships with adult children were analyzed additionally. Findings show that married older adults were older and reside with their adult children twice more than those who do not have a spouse. According to research results, regular exercise and memory skills were important factors of affecting life satisfaction. Among the categories of active engagement, meeting with friends, relatives and neighbors were significant. Contact with their adult children by mail or phone were the most important factors affecting the older adults' life satisfaction. The three parts of successful aging were various depending on the operationalization of variables.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제20권5호
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• pp.7-12
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• 2019

The naval surface vessels, which were often exposed to harsh marine environment, tended to be corrosive due to military operations on various sea-areas and courses. Although R.O.K Navy applied various methods to protect further corrosion, the hull corrosion occurred due to cavitation were found on the naval surface vessels at regular and occasional docking. Hull corrosion was a critical factor directly to affect the lifetime of ships and their operational capabilities adversely. In this paper, EH 2350, which was the main anticorrosion paint used by R.O.K. Navy, was compared with DuraTough DL by used by the U.S Navy to collect materials related to anti-corrosion paint. In addition, the paint compatibility verification was conducted through wear abrasion test. Assuming that it was exposed to sea-environment various both abrasion cycle and weight for objective verification. by varying both the abrasion cycles and weights. In this study, the reliability of the EH 2350 conformity, which was used in Naval surface vessels, was secured.

• Journal of Adhesion and Interface
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• 제20권1호
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• pp.9-14
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• 2019

The change of three different reagents for electrical conductive paint using aircraft coating with elapsing time of exposure to different condition was investigated. Three different reagents were poured into the vial bottles, stored in air condition and room temperature and observed with elapsing days. In addition, adhesion property of paint was tried using cross cut tape test after storage of $N_2$ atmosphere. The weight of each different reagent was measured along with elapsing time. To confirm the change of chemical component with exposure of air atmosphere, FT-IR was performed. The weight of part A and Part B decreased slightly whereas the weight of part C decreased rapidly and the precipitation was remained. The part B was cured after exposure of $N_2$ atmosphere and the 2250 cm-1 from FT-IR peak decreased slowly at the same time. It was considered that the water contained in air accelerated the reaction of -NCO functional groups and it caused the curing whereas $N_2$ atmosphere not contained water and it resulted in the retardancy of curing.

• Applied Chemistry for Engineering
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• 제22권2호
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• pp.161-166
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• 2011

The $CO_2$ dry reforming reaction, which converts carbon dioxide to hydrogen and carbon monoxide, is typical endothermic reaction, and also known as adverse reaction owing to thermodynamics. In order to overcome the problem, the development studies of suitable catalyst based on precious metals for high durability of thermal and optimization of life time have been examined but it had economical problem by high cost. In this study, we confirmed optimum contents of Pt and La with such different contents of Pt (0.02~0.2 wt%) or La (2~20 wt%) over $Co/SiO_2$ which prepared for excellent activity and cost-effective catalysts. As a result, the promoted catalysts with 0.04 wt% Pt or 9 wt% La over $Co/SiO_2$ showed the highest activity which is 57% and 55% $CO_2$ conversion respectively. Also, the particle size of cobalt on the promoted catalysts with 0.04 wt% Pt or 9 wt% La by characterization of catalyst could confirm the smallest particle size in this study. Therefore, it could know that particle size of cobalt had effected the stability and reactivity of catalysts due to the contents of Pt and La.

• Journal of the Korean Regional Science Association
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• 제37권1호
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• pp.29-44
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• 2021

Particulate matter(PM) is one of the leading causes of lung cancer. Recognizing its considerable risk to human health, people change their behaviors when a concentration level of PM is high. The impact of particulate matter on urban activities may vary depending on the lasting days of PM and PM matter alerts. In addition, the level of averting behavior may vary depending on the types and physical characteristics of urban activities and the degree of vulnerability to PM among people. Although the way people respond to PM may vary depending on these various factors, previous research evidence on this is very insufficient. Therefore, this study multilaterally analyzed the impact of PM on the urban activities in Jongno-gu, one of the CBD areas of Seoul. For this, we linked SKT's mobile phone signal data to land use data to extract the daily number of active people by urban activity types and ages. According to multiple regression analysis, the averting behavior varies depending on the type of urban activity, the physical characteristics of the place of activity(inside and outdoor), the lasting days of PM, PM alerts and the age of people. The results of this study can be used as basic data to policy makers who establish policies for adapting to air pollution policies by providing various effects of PM on the urban activities.

• Journal of the Korean Applied Science and Technology
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• 제38권1호
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• pp.19-28
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• 2021

Corrosion is the degradation of metals by reaction with the environment. It is difficult to completely remove. Corrosion proceeds rapidly after the protective barrier is destroyed, and several reactions occur that alter the composition and properties of the metal surface and local environments, such as diffusion of metal cations into the matrix, the formation of oxides, and local pH changes. The study of corrosion of steel and iron is of theoretical and practical interest and is receiving considerable attention. Acid solutions, which are widely used in industrial pickling, acid descaling, cleaning and acidification of oil wells, require the use of corrosion inhibitors to suppress corrosion attacks on metallic materials. Physical removal of rust requires expensive special equipment, and chemical removal of it can cause corrosion or shorten the life of the metal. In this study, an eco-friendly rust cleaner was developed using cosmetics and food materials by applying the concept of perm reducing agent and chelate, and applied to remove rust from industrial and hot water pipes and various industrial devices. As a result, it was found that rust cleaners remove rust more effectively and safely compared to conventional treatment methods. At the same time, the rust removal efficiency was 1.75 to 2.5 times better for industrial piping and 1.56 to 2.2 times better for boiler hot water than conventional methods.

• Korean Journal of Plant Resources
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• 제35권2호
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• pp.183-191
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• 2022

Ginseng (Panax ginseng C.A. Meyer) is a perennial plant and propagates by seeds, and those need after-ripening for germination. To be ready for climate change and to ensure a stable seed supply, the technique for storing seeds in short-term and long-term in large quantities is required. In this study, dehisced ginseng seeds from two locations, batch #1 and batch #2, were stored at -3.5℃ with different moisture content, and after 3, 15, and 27 months of storage, the percentage of radicle emergence and shoot emergence were measured. After 3 months, radicle emergence and shoot emergence were normal only when the seed moisture content was more than 35%, and overall, germination was higher in batch #2 than in batch #1. After 15 months, the partially dehydrated seeds, with a moisture content between 45 to 54%, showed the highest germination rates, and most of the undried seeds were spoiled and failed to germinate. Seeds with moisture content lower than 25% had poor germination, too. The partially dehydrated seeds also succeeded in germination and growth in the soil after 15 months of storage, but deteriorated after one more 1 year, too. In summary, ginseng seeds look like have temperate recalcitrant seed characteristics, and partial dehydration allows extension of seed longevity.

• Journal of the Korea institute for structural maintenance and inspection
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• 제26권5호
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• pp.86-94
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• 2022

Replacement of FRP rod as steel reinforcement has been attracted significantly to prevent the degradation of the concrete structure due to corrosion. So, the technology development to extend the structure's service life by improving FRP properties has been proceeded worldwide. Accordingly, it is necessary to develop Korea's CFRP rod and CFRP grid, including the manufacturing techniques to improve the properties of high-strength and high-stiffness. Moreover, the research should be conducted to evaluate the structural behavior of the beams using the CFRP rod or grid. This study investigates the flexural and shear behavior of reinforced concrete beam using demonstrated CFRP rod as reinforcement according to the reinforcement ratio and shear span to depth ratio. From the results, when the reinforcement ratio is out of a specific range, it is seemed that the effect on performance improvement of the beam using CFRP rod is cancelled or not significant. Meanwhile, when the CFRP rod was used as reinforcement, the possibility of shear failure occurred, even steel stirrups were installed in the beam with CFRP rod as tensile reinforcement according to the Korean Design Standard. Therefore, when the CFRP rod is used as tensile reinforcement in a beam, it should be prepared that a specific limitation of reinforcement ratio and an investigation against shear failure. Also, the ductility of the beam using the CFRP rod is determined by the deformation energy evaluation method. So, the ductility should be investigated by applying the deformation energy evaluation method that reflects the structural behavior of the beam.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제32권6호
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• pp.251-261
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• 2022

This paper describes the finite element analysis and die design change of spring retainer forging process to reduce the cold forging load and plastic forming stress concentration. Plastic deformation analysis was carried out in order to understand the forming process of workpieces and elastic stress analysis of the die set was performed in order to get basic data for the die fatigue life estimation. Cold forging die design was set up to each process with different four types analysis progressing, the upper and lower dies shapes with combination of fillets and chamfers shapes of cold forging dies. This study suggested optimal cold forging die geometry to reduce cold forging load. The design parameters of fillets and chamfers are selected geometry were selected to apply optimization with the DoE (design of experiment) and Taguchi method. DoE and Taguchi method was performed to optimize the workpiece preform shape for spring retainer forging process, it was possible to expect an increase in cold forging die life due to the 20 percentage forging load reduction.