• Journal of Korean Institute of Industrial Engineers
• /
• v.41 no.6
• /
• pp.551-558
• /
• 2015

The purpose of this paper is to investigate the development of mechanical projectile transfer system to prevent musculoskeletal problems in the firing test range. Prior to 2010, the projectile has been transferred from the worktable to the loading device of 155mm K9 fixed-type artillery by manual. Because the amount of firing test has been increased drastically since 2010, two types of mechanical projectile transfer system were developed to prevent musculoskeletal problems. The NIOSH lift equation and the working posture assessment system such as OWAS, RULA and REBA were used to evaluate the appropriacy of working weight and posture by manual transfer of projectile. The configuration and operation procedure of projectile transfer systems which were developed to improve work efficacy and to reduce the burden of manual transferring were described. The improvements were assessed by the number of processes, the tact time and the working posture assessment for operation of this system by comparing to the manual transfer of projectile.

• Advances in concrete construction
• /
• v.11 no.1
• /
• pp.59-71
• /
• 2021

This research aims to study the utilization of olive waste ash (OWA) in the production of concrete as a partial substitute for cement. Effects of using OWA on the physical and mechanical properties of concrete mixtures have been investigated. This is done by carrying out tests involving the addition of various percentages of OWA to cement (0%, 5%, 10% and 15%). For each percentage, tests were performed on both fresh and hardened concrete; these included slump test, unit weight test and compressive strength test after 7, 28 and 90 days. Durability tests were investigated in solutions containing 5% NaOH and MgSO4 by weight of water. In addition, resistance to high temperatures was tested by subjecting the cubes to high temperatures of up to 170℃. The results of this research indicate that a higher percentage of OWA gives a lower compressive strength and lower workability but higher performance in terms of durability against both different weather conditions and high temperatures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.95-98
• /
• 1999

Recently, the use of the underwater concrete constructions with the antiwashout underwater concrete is increasing. In this study, we investigate the properties of pH, suspended solids, slump flow, box test, air contents of fresh antiwashout underwater concrete and the Unit weight, compressive strength of hardened antiwashout underwater concrete which Ground Granulated Blast Furnace Slag contents 0%, 10%, 20%, 30%, 50%, 60% at 7days and 28days age which is produced and cured in the water and sea water. As a result, Ground Granulated Blast Furnace Slag contents 30% was excellent.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.141-146
• /
• 2001

Permeable polymer concrete has a lot of internal voids, which has more excellent performance in permeability and durability than asphalt and cement concrete. Therefore, in this paper, influences of grading distribution of aggregates on the permeable polymer concrete are presented using polyester resin as binders. According to test results, it shows that compressive strength and unit weight increase with continuous grading distribution and increase of binder content, while void and permeability coefficient shows decline tendency

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.111-116
• /
• 2002

Permeable polymer concrete has a lot of internal voids, which has more excellent performance in permeability and durability than asphalt and cement concrete. Therefore, in this paper, influences of grading distribution of aggregates on the permeable polymer concrete are presented using polyester resin as binders. According to test results, it shows that compressive strength and unit weight increase with continuous grading distribution and increase of binder content, while void and permeability coefficient shows decline tendency.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.166-171
• /
• 1999

Porous concrete contains about 20% voids after compaction so that it has high permeability which secures underground water resources. It is introduced in domestic since 1980' but has problems such as lack of optimized mixture, low strength and durability, efflorescence and other defects, etc. In this study, several mixture were designed based upon site works, and test specimens for compressive strength, tensile strength, flexual strength and permeability, were prepared in a laboratory. After 28days of curing, every performance was tested to find optimum mixture. The mixture was proposed as 380kg/㎥ of unit cement weight, 32% of W/C 10∼13mm of aggregate.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.93-96
• /
• 2000

In this paper, physical properties of planting concrete using Recycled aggregates made with demolished concrete and construction wastes are investigated. According to the test results. It shows that recycled aggregates made with demolished concrete and construction wastes have low physical properties compared with crushed stone. But, recycled aggregates made with construction wastes shows better performance in absorption ratio, unit weight and thermal conductivity than crushed stone. According it is thought that they are available for being applied to planting concrete considering the sides of efficient recycling of construction wastes and saving the manufacturing cost.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.10a
• /
• pp.140-145
• /
• 1991

Tests were conducted to get a mix proportioning of high strength concrete between σ28 and (C/W) using low quality materials easily purchased in situ. Superplasticizer was used as a chemical admixture to compensate low slump of base concrete keeping it up about 15±2㎝. General material properties such as modulus of elasticity, poisson's ratio, unit weight and stress-strain characteristic of high strength concrete were obtained. Test results show that mix proportioning of high strength concrete proposed in this paper have reasonable validity and these can be used as a design criteria in high strength concrete construction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.3
• /
• pp.189-196
• /
• 2008

The increase of system weight due to installation of cooling devices adds electrical and mechanical loads of humanoid robot, and in return, results in much heat. Therefore, the weight of cooling system is a critical issue for robot cooling. In this study, we propose non-metallic cold plates to deal with such problems. We compare thermal performances between one metallic cold plate and five different types of non-metallic cold plates. A metallic cold plate is totally made of copper. Five non-metallic PC(polycarbonate) cold plates, which are designed to reduce the overall weight of robot cooling system, are composed of a polycarbonate cover with different types of base plate. The overall heat transfer coefficients per unit mass and thermal resistances are obtained for the cold plates. The metallic cold plate shows the best thermal performance. It is interesting to note that the PC cold plate with an aluminum base plate with 18 channels shows the best overall heat transfer coefficient per unit mass. Most polycarbonate cold plates display fairly comparable thermal performance with more reduced system weight compared to the metallic cold plate.

• Journal of Korean Physical Therapy Science
• /
• v.11 no.2
• /
• pp.18-26
• /
• 2004

The purpose of this study was to compare difference of the static and dynamic balance in normal subject and LBP subject and recognizes about postural sway. The subjects of this study included 30 normal subjects and 30 LBP subjects. By using Active balance system, the static balance was measured by unit path length, circumference area, weight bearing, stabilometry length, while the dynamic balance was measured by step evaluation. Statistically analyzed using independent t-test to search static balance and dynamic balance difference in two groups. Postural sway appeared greatly in patient group than normal group in analysis result of static balance and postural sway was big in patient group of when closed eye and normal group and patient group did show statistical significance in unit path length, circumference area. Weight support of normal group was shared equally in weight bearing rate, but weight support of patient group stewed less to pain side. Anterior step time and Task achieve time of dynamic balance were spent more in patient group than normal group. Desire to be used to useful information to lay treatment policy about set-up and action of when quantification result of valued postural balance treats low back pain patient by objective tool, in the fixture, more researches in postural estimation desire that is enforced abuzz.