• Korean Journal of Poultry Science
• /
• v.20 no.3
• /
• pp.141-149
• /
• 1993

In order to develop a poultry manure dryer, a pilot dryer was designed and drying experiments were conducted to investigate the drying characteristics of poultry manure. According to the results, the pilot dryer could be operated without any air pollution problems. When poultry manure was dried from 79.2%(w.b. basis) moisture content, the final moisture content ranged from 38.7% to 57.9% depending upon the drying conditions. The drying results showed that drying rate was 189.8~198.0 kg/h and moisture evaporation rate was 124.0~125.4kg-$H_2$O/L. For this drying, electricity requirement was 9.5~19.3 Wh/kg and fuel consumption rate was 6.9~9.3 kg-$H_2$O/L with 50.2~65.1% thermal efficiency.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.4
• /
• pp.545-552
• /
• 2021

In this study, strength and durability evaluations are performed on vibrated-rolled method mortar mixtures containing desulfurized gypsum and ferronickel slag powder. Desulfurized gypsum and ferronickel slag fine powders were substituted for 25% limestone fine powders u sed in the manu factu re of VR tu bes, and mortar specimens were prepared u sing vibrated-rolled method. Accordingly, flexural and compressive strengths were performed to evaluate the strength, and chlorine ion penetration resistance and sulfuric acid resistance tests were performed to evaluate durability. Flexural and compressive strength were improved in the range 20 to 60% of desu lfu rized gypsu m among admixtu res, and the amou nt of passing charge decreased in the choride ion penetration resistance test in the range of 20 to 80% of desulfurized gypsum. As for the resistance to su lfu ric acid, when the proportion of desu lfu rized in the admixtu re was 40%, the strength and weight change rate according to the immersion period was reduced. Appropriate use of desulfurized gypsum and ferronickel slag powder is expected to improve performance in terms of strength and durability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.6
• /
• pp.573-582
• /
• 2021

In this study, a series of processes for evaluating the effective protection against barriers that should be equipped in institutions that perform reliability tests on high-risk ammunition, such as high-explosive ammunition, were introduced. The impact that high-explosive bombs can have on personnel includes damage to the eardrum and lungs caused by explosion overpressure and penetrating wounds that can be received by fragments generated simultaneously with the explosion. Therefore, a high-explosive with COMP B explosives as its contents were set up, and an explosion protection theory investigation to calculate the degree of damage, numerical calculations and simulations were performed to verify the protection power. A numerical calculation revealed the maximum explosion overpressure on the protective wall when the high-explosive exploded and the penetration force of the fragment against a 50 mm-thick protective wall to be 77.74 kPa and 41.34 mm, respectively. In the simulation verification using AUTODYN, the maximum explosion overpressures affecting the firewall and personnel were 56.68 kPa and 18.175 kPa, respectively, and the penetration of fragments was 35.56 mm. This figure is lower than the human damage limit, and it was judged that the protective power of the barrier would be effective.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.2
• /
• pp.18-27
• /
• 2022

In this study, the time-dependent chloride ingress behavior in GGBFS concrete was evaluated considering marine exposure conditions and the properties of concrete mixtures. The concrete mixture for this study had 3 levels of water to binder ratio and the substitution rate of GGBFS, and outdoor exposure tests were performed considering submerged area, tidal area, and splash area. According to the evaluation results of diffusion coefficient considering properties of concrete mixtures, as the substitution rate of GGBFS increased, the decreasing rate of the diffusion coefficient decreased based on exposure periods of 730 days(2 years). As the evaluation result of the diffusion behavior according to the marine exposure conditions, the diffusion coefficient was evaluated in the order of submerged area, tidal area, and splash area. In tidal area, a relatively high diffusion coefficient was evaluated due to the repetition of wet and dry seawater. In this study, the effects of GGBFS substitution rate on the decreasing behavior of apparent chloride diffusion coefficient was analyzed in consideration of exposure conditions and periods. Linear regression analysis was performed with apparent chloride diffusion coefficient as output value and GGBFS substitution rate as input value. After 730 days of exposure, the effect of GGBFS on diffusion coefficient was significantly reduced. Even for OPC concrete, after 730 days, the diffusion coefficient was as low as that of GGBFS concrete, so the gradient of the regression equation decreased significantly. It is thought that improved durability performance for chloride ingress can be secured before 730 days through the use of GGBFS.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.6
• /
• pp.825-836
• /
• 2022

Micropiles can be used to support additional load in extended building structures. However, their use brings about a risk of exceeding the bearing capacity of existing piles. In this study, pre-compression was applied to distribute the load of an existing building to micropiles, and an indoor loading test was performed to confirm the structural applicability of a wedge-type anchorage device designed to improve its capacity. According to the test results, the maximum strain of the anchorage device was 0.63 times that of the yield strain, and the amount of slip generated at the time of anchorage was 0.11 mm, satisfying structural standards. In addition, using MIDAS GTS, a geotechnical finite element analysis software, the effect of the size of the pre-compression, the thickness of the soil layer, and the ground conditions around the tip on the reaction force of the existing piles and micropiles were analyzed. From the numerical analysis, as the size of the pre-compression load increased, the reaction force of the existing pile decreased, resulting in a reduction rate of up to 36 %. In addition, as the soil layer increased by 5 m, the reduction rate decreased by 4 %, and when the ground condition at the tip of the micropile was weathered rock, the reduction rate increased by 14 % compared with that of weathered soil.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.12 no.3
• /
• pp.254-262
• /
• 2024

The demand for high strength and ultra-lightweight materials to incorporate the advanced technology of nanomaterials into the lengthening of structures is continuously increasing. Therefore, based on existing research results and numerous mixing trials, we derived a mix of high strength and ultra-light concrete of a compressive strength of 100 MPa with a unit weight of 18 kN/m³ and a compr essive str ength of 80 MPa with a unit weight of 16 kN/m³ and evaluated their per for mance. In this paper, 108 specimens corresponding to high strength and ultra-lightweight concrete with a compressive strength of 100 MPa under a unit weight of 18 kN/m³, and a compressive strength of 80 MPa under a unit weight of 16 kN/m³ were manufactured, and the bond characteristics were identified by performing a directly tensile tests, and the bond characteristics were evaluated by comparing them with the experimental results and the current design criteria. It was judged that the bond strength calculation formula of ACI-408R and the experimental results were not accurately reflected, so an bond stress equation based on ACI-408R was proposed. The result of the proposed equation was that the deviation was somewhat reduced. In addition, the results of calculating the CEB-FIP model and the modified CMR model using statistical analysis showed slight differences from the experimental results, but considering that the bond behavior is a local behavior, the proposed model appears to explain the bond behavior of high strength and ultra-light concrete as a whole.

• Fire Science and Engineering
• /
• v.34 no.1
• /
• pp.47-54
• /
• 2020

This paper proposes a solution to the problems of constructing and installing sway braces for existing standpipes in narrow spaces and pits. The study develops a floor-fixed sway brace for a narrow space that can support the ground area under horizontal seismic loads (X-axis, Y-axis) as well as vertical seismic loads (Z-axis). The results of structural analysis using SolidWorks simulation showed that the eccentric load was generated in the first design according to the anchored position along the vertical direction, and the problem of exceeding the allowable stress of the material along the horizontal and vertical directions. In the second design model, deformation caused by the eccentric load along the vertical direction, similar to the first design model, did not occur. The maximum strain rate was 0.17%, which is approximately 12.84% less than the first design model (Maximum strain rate of 13.01%). It was confirmed that the structural stability and durability improved. Compressive and tensile load testing of the prototypes showed that all of them meet the performance criteria of the standard.

• International Journal of Highway Engineering
• /
• v.8 no.3 s.29
• /
• pp.77-88
• /
• 2006

The maintenance / repair of concrete pavements has become an issue as a result of increasing of concrete pavements' service year. Asphalt overlay is applied to the concrete pavements after partial repairs on all occasions. This thesis discusses the application standard, evenness, skid resistance, noise, economical efficiency, extension of life span, etc. of diamond grinding, a method of maintenance about concrete pavements. Based on this, it was applied to the field and measured the performance. It was measured the longitudinal evenness of before and after the construction through measurement equipment. and surveyed the skid resistance the each lane classified using the SN standard value. In case of noise, it is selected the kind of vehicle, velocity, then measured the noise between control and constructed site. In addition, it is evaluated the average texture depth. As a result of the analysis, longitudinal evenness is improved about $6{\sim}40%$, skid resistance is improved 66% at first section,37% at second section. Noise is reduced 3.4dB average, and average texture depth is 79% deeper than control section. Therefore, it can be concluded that diamond grinding is suitable as maintenance / repair method of concrete pavements.

• International Journal of Highway Engineering
• /
• v.12 no.2
• /
• pp.9-16
• /
• 2010

Roughness is the most important factor to maintain the road performance, and affects greatly on the design life in Jointed Plain Concrete pavements. Also, the factors the evaluate pavement‘s commonality is the three method such as functionality, safety and structural performance. In evaluating function of road, representative factors is the roughness, which has been used to determine maintenance time as key standard. As research for roughness is absence in pavement design. Applied roughness-model had a low-reliability in Korea. Therefore, it is needed to develop reliable model in road roughness. In this research, uniform specific is applied to distribute them after selecting the concrete pavements. Concrete pavement is divided by sections of 238. Total length of this sections has 281km and account for 16% of total road length in korean concrete pavements for selected sections. Considering the korean roughness-model, the evaluation of roughness is performed for the freezing index, average annual rainfall, condition for the base, the amount of traffic as well as spalling(%), cracking(%), age(year) at the selected section at the selected section. Also, additional sections is selected to evaluate various age which affects on the roughness. As a result of the analysis, it showed that spalling(%), cracking(%), age(year), and the condition of the base affected road roughness. When the correlation with the road roughness was analyzed, the reliable model for road roughness was proposed, and the ratio that can explain road roughness was R2-68.8% and P value-0 which is statistically meaningful.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.4 s.304
• /
• pp.31-38
• /
• 2005

In this paper, we propose the chromatic adaptation models (CAM) for the variations of the luminance levels. A chromatic adaptation model, CAM$\Delta$Y , is proposed according to the change of luminance level under the same illuminants. The proposed model is obtained by the transform the test colors of the high luminance into the corresponding colors of the low luminance. In the proposed model, the optimal coefficients are obtained from the corresponding colors data of the Breneman's experiments. In the experimental results, we confined that the chromaticity errors, $\Delta$u'v', between the predicted colors by the proposed model and the corresponding colors of the Breneman's experiments are 0.004 in u'v' chromaticity coordinates. The prediction performance of the proposed model is excellent because this error is the threshold value that two adjacent color patches can be distinguished. Additionally, we also propose equal-whiteness CCT curves (EWCs) by CAM$\Delta$Y according to the luminance levels of the surround viewing conditions. And the proposed EWCs can be used as the theoretical standard which determines the reference white of the color display devices.