• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.219-224
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• 2011

The health status of three groups of Hanwoo steers (n=157) aged 2-3 years, raised at three different altitudes (600 m, n=50; 200-400 m, n=58; plane land, n=49) and environment with more or less similar management have been evaluated through hematological, biochemical and globulin examinations in order to determine the optimum environment suitable for raising cattle while at the same time minimizing the risk of disease. Five mL of blood samples from each animal were collected by jugular veinipuncture and 2 mL was transferred to a tube containing EDTA for complete blood count (CBC) and 3 mL in lithium heparin for chemistry screening (CS) and immunoassay. Among the CBC parameters a significantly higher white blood cell count (tWBC), total red blood cell count (tRBC), hemoglobin (Hb) and packed cell volume (PCV) were noticed in the high altitude groups, whereas those were lower in the plane land group. In the CS parameters higher levels of aspartate aminotransferase (AST), creatinine, lactate dehydrogenase (LDH) and total bilirubin (TBL) were found in the plane land group, whereas those were lower in the high altitude groups. The total protein (significantly) and globulins were higher in the 600 m group. The results of this study revealed that the overall health status of the Hanwoo cattle based on the hemato-biochemical indices was superior in the highest altitude and inferior in the plane land group but all the parameters were within the reference range in all the groups. Therefore, for recommendation of a suitable environment at an appropriate altitude for raising cattle there need to be further studied along with the hemato-biochemical parameters; considering, breeding, feeding, management, marketing, waste disposal and other factors.

• Analytical Science and Technology
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• v.23 no.2
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• pp.138-146
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• 2010

The Korean Ministry of the Environment revised a few sections of the regulations in the Law of indoor air quality management for the reinforcement or adjustment of the regulation criteria standard for releasing pollutants from building materials. Especially, in case of sealant, the contents covering liquid building materials, excess standards and testing methods have been added simultaneously in this revision, As a result it is impossible to compare original standards with revised standards directly. For this reason, this study reviewed revised test method of sealant pollutant emission rates in terms of impact and validity in comparison with the original test method. Through this study, the basic properties of revised pollutant emission control standards was assessed. Especially in sealant, since each product has a wide deviation of time required for complete drying, it is proved that there are a large number of products that are not hardened completely in test time. The result of our experiments on the revised test methods showed that this revised test methods yield emission rates that are two and half times less than those of the original testing method. To apply the revised test method of sealant to all the sealant products, It is necessary to extend the test period or improve specimen to fit the test method for quickly drying sealant products.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.587-596
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• 2011

Ultra rapid-hardening cement is widely used for latex-modified mortar and concrete as repair and finishing material during urgent work. The purpose of this study is to evaluate the improvements in strength made to SBR cement mortars by the adding of various admixtures and by the use of different curing methods. SBR cement mortar was prepared with various polymer-cement ratios, curing conditions and admixture contents, and tested for flow, flexural and compressive strengths. From the test results, it was determined that the flow of SBR cement mortar increased with an increase in the polymer-cement ratio, and the water reducing ratio also increased. The strength of cement mortar is improved by using SBR emulsion, and is strengthened by adding metakaoline. The strength of SBR cement mortar cured in standard conditions was increased with an increase in the polymer-cement ratio, and attained the maximum strengths at polymer-cement ratios of 15 % and 10 %, respectively. The maximum strengths of SBR cement mortar are about 1.8 and 1.3 times the strengths of plain mortar, respectively. In this study, it is confirmed that the polymer-cement ratio and curing method are important factors for improving the strengths of rapid-hardening SBR cement mortar.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.305-313
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• 2012

Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.

• Journal of the Korea Institute of Building Construction
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• v.16 no.2
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• pp.107-115
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• 2016

In this study, the bond strength of metal spraying system by surface treatment of concrete (waterproof/corrosion method) in water treatment facilities was evaluated. The results showed that the system with Sa-P-R-(S) (sanding-perviousness surface hardener-surface roughness agent-metal spraying-sealing) led to the desirable performance. The bond strength, the coefficient of water permeability and air permeability were 3.7MPa, $0.68{\ast}10^{-8}cm/sec$, and $0.45{\ast}10^{-16}m^2$, respectively. In scanning electron microscope analysis, the microstructure of specimen coated with perviousness surface hardener was much denser than that without it. Therefore, the specimen coated with sanding-perviousness surface hardener-surface roughness agent-metal spraying-sealing had the best bond performance and was the most suitable system to concrete surface in water treatment facilities.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.163-173
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• 2010

A significant number of projects have been managed by US Army Corps of Engineers FED. Today, more information must be provided to the parties involved in the projects by phase than ever before. Specifically, USFK`s construction projects have been managed by FED(Far East District). Recently, however, large US private construction companies have been filling the role previously taken by FED. However, there is few construction managers to implement FED project in Korea. Accordingly, this study analyzes FED projects practices with focus on the construction management actors in order to suggest guideline. This study suggests a model FED construction process(Bid, Contract, Construction, As-Built Phase) by analyzing the existing FED project process using a IDEF0 methodology.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.57-63
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• 2010

The bearing wall apartments which occupy the majority of multi-residential apartment buildings built in Korea, are known for having limited architectural plan flexibility, posing challenges in terms of maintenance and remodeling. The economic losses and environmental issues resulting from the reconstruction of bearing wall apartments are now accumulating to the extent that they are becoming a national concern. Multi-residential apartment buildings, which are now the dominant form of residence in Korea, must accommodate diverse customer needs and changes in life style. A new concept of Rahmen structure with architectural flexibility is Green Frame. GF multi-residence housing is expected to reduce construction costs and shorten the construction schedule by overcoming the shortcomings of conventional bearing wall apartments. This goal is consistent with the national policies that target the reduction of resource and energy consumption. In addition, GF will be established as a core contributor to achieving a reduction in $CO_2$ emissions, which will enable the sustainable growth of domestic construction industry, and address the low-carbon green growth drive implemented by the government.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.391-397
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• 2020

This study is to compare and analyze the strength, drying shrinkage and carbonation properties of lightweight aggregate mortar using recycling water as prewetting water and mixing water. The flow, compressive strength, split tensile strength, drying shrinkage and carbonation depth of lightweight aggregate mortar with recycling water were measured. As test results, the mortar flow was similar in all mixes regardless of the recycling water content. The compresseive strength of the RW5 mix with 5% recycling water as prewetting water and mixing water was the highest value, about 53.9 MPa after 28 days. In addition, the tensile strength of lightweight mortar was about 3.4 to 3.8 MPa, indicating 7 to 9% of the compressive strength value regardless of recycling water content. In the case of drying shrinkage, the RW2.5 mix using 2.5% recycling water showed the lowest shrinkage rate as about 0.107% at 56 days. The drying shrinkage of the plain mix without recycling water was relatively higher than the RW2.5 and RW5 mix. The RW5 mix showed lowest carbonation depth compared to other mixes. In this study, the RW5 lightweight aggregate mortar with 5% recycling water exhibits excellent compressive strength and carbonation resistance. Therefore, it is considered that if the recycling water, a by-product of the concrete industry, is properly used as prewetting water and mixing water of lightweight mortar and concrete, it will be possible to increase the recycling rate of the by-product and contribute to improve the property of lightweitht aggregate mortar and concrete.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.399-407
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• 2020

The aim of the research is to provide the boundary conditions for segregation of normal strength grade and high fluidity concrete mixture (so called mid-fluidity concrete) with rheology parameters. Since the normal strength grade concrete mixture has a relatively high water-to-cement ratio and no SCMs, it is easy to be segregated when superplasticizer is added. Hence, to achieve the mid-fluidity concrete of normal strength grade and high fluidity, preventing segregation of the mixture is inevitable. In this research, using two superplasticizers with different solid concentrations, the flow behaviors and rheological behaviors were assessed by increasing fluidity until the segregation happened. According to the experiment in this research, an unusual behavior in rheology parameters was observed when the concrete mixture started to be segregated. From this results and report, it is expected to contribute on the definition of segregation with rheological test methods.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.227-234
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• 2018

Researches regarding measurement and control of the dynamic behavior of liquid such as sloshing have been actively on undertaken in various engineering fields. Liquid vibration is being measured in the study of tuned liquid dampers(TLDs), which attenuates wind motion of buildings even in building structures. To overcome the limitations of existing wave height measurement sensors, a method of measuring liquid vibration in a TLD using a laser Doppler vibrometer(LDV) and galvanometer scanner is proposed in this paper: the principle of measuring speed and displacement is discussed; a system of multi-point measurement with a single point of LDV according to the operating principles of the galvanometer scanner is established. 4-point liquid vibration on the TLD is measured, and the time domain data of each point is compared with the conventional video sensing data. It was confirmed that the waveform is transformed into the traveling wave and the standing wave. In addition, the data with measurement delay are cross-correlated to perform singular value decomposition. The natural frequencies and mode shapes are compared using theoretical and video sensing results.