• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2023년도 추계학술대회
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• pp.199-201
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• 2023

VDES는 2015년 ITU-R M.2092-0가 발행된 이후로 다년간 기술 개발 및 개정 작업을 통해 2022년에 ITU-R M.2092-1이 발행되었다. 2026년 1월부터 VDES를 필수 규제 체계에 도입하기 위해 IMO는 2021년 MCS 103회의를 시작으로 NCSR 10에서 SOLAS 4장 및 5장의 수정안과 성능 기준 및 지침 개발을 논의하였고 24년 6월이면 작업이 완료될 것으로 예상된다. 자율운항선박 과제에서는 VDES를 이용하여 자율운항 선박의 안전관련 필수 정보들을 육상-선박 뿐만 아니라 선박-선박 연결에서도 데이터 교환을 할 수 있도록 VDES 시스템을 통신 방식 중 하나로 적용하여 개발하고 있으며 최신의 VDES 관련 표준을 유지할 수 있도록 지속적인 표준 분석 및 시스템 적용을 수행하고 있다. 본 논문에서는 VDES의 MAC 계층 설계를 위해 IEC에서 개발 중인 시험 표준을 분석하고 VDES 개발 시제에 적용하여 검증 및 평가를 수행하였다.

• Journal of Animal Science and Technology
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• 제45권5호
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• pp.787-796
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• 2003

Two experiments were conducted to investigate the effect of germanium biotite (GB) on growth performance, nutrient digestibility and fecal gas emission in pigs. In Exp 1., a total of one hundred nursery pigs (initial body weight 13.12${\pm}$0.15kg) were used in a 21 d growth assay. The five treatments were control (CON, basal diet), GB0.5-200 (basal diet + 0.5% GB, 200mesh), GB1.0-200 (basal diet + 1.0% GB, 200mesh), GB0.5-325 (basal diet + 0.5% GB, 325mesh), GB1.0-325 (basal diet + 1.0% GB, 325mesh). Each treatment had four replicates with five pigs per replicate. ADG, ADFI and gain/feed were not significantly different among the treatments. Fecal NH3-N concentration of pigs fed the GB325 diet was lower than that of pigs fed the GB200 diet (P=0.01). The GB treatments reduced fecal volatile fatty acids significantly compared to the CON (propionic acid, P=0.01; butyric acid, P=0.01; acetic acid, P=0.02). Especially, fecal propionic acid concentration of pigs fed the GB325 diets was lower than that of pigs fed the GB200 diets (P=0.02). In Exp 2., a total of seventy five pigs (initial body weight 21.18${\pm}$0.15kg) were used in a 28 d growth assay. The treatments were same as described for Exp. 1. Each treatment had five replicates with three pigs per replicate. The GB1.0 treatments significantly increased the ADG compared to the GB0.5 treatments (P=0.03). The DM and N digestibility of pigs fed the GB1.0 diets were higher than that for pigs fed the GB0.5 diets (P=0.01). Also, the Ca digestibility of pigs fed the GB diets was higher than that for pigs fed the CON diets (P=0.01). The fecal NH3-N concentrations for the GB treatments were lower than that for the CON (P=0.01). The GB325 treatments significantly decreased the fecal NH3-N concentration compared to the GB200 treatments (P=0.03). The fecal butyric acid concentration for the GB325 treatments was lower than that for the GB200 treatment (P=0.04). In conclusion, the results obtained from these feeding trials suggest that the dietary GB for nursery pigs affects fecal noxious gas emission. In growing pigs, dietary GB was effective to improve ADG and decrease fecal noxious gas emission.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제36권11호
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• pp.1345-1352
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• 2012

This paper aims to evaluate the low-velocity impact responses and mechanical properties of balsa-wood and urethane-foam core materials and their sandwich panels, which are applied as the impact limiter of a nuclear spent fuel shipping cask. For the urethane-foam core, which is isotropic, tensile, compressive, and shear mechanical tests were conducted. For the balsa-wood core, which is orthotropic and shows different material properties in different orthogonal directions, nine mechanical properties were determined. The impact test specimens for the core material and their sandwich panel were subjected to low-velocity impact loads using an instrumented testing machine at impact energy levels of 1, 3, and 5 J. The experimental results showed that both the urethane-foam and the balsa-wood core except in the growth direction (z-direction) had a similar impact response for the energy absorbing capacity, contact force, and indentation. Furthermore, it was found that the urethane-foam core was suitable as an impact limiter material owing to its resistance to fire and low cost, and the balsa-wood core could also be strongly considered as an impact limiter material for a lightweight nuclear spent fuel shipping cask.

• Journal of the Korean Geosynthetics Society
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• 제9권2호
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• pp.33-40
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• 2010

In this study, the pullout tests are conducted to evaluate pullout resistance of steel strip reinforcement with transverse members. The test results are compared with theoretical equations and then the failure mechanism of transverse members is evaluated. The bearing resistance stress(${\sigma}^{\prime}_b$) of transverse members, which is applied pullout force at 50mm displacement, is closed from punching shear failure to general shear failure. The behavior by increment of a number of transverse members became closer to general shear failure. The behavior of transverse members at maximum pullout force, which is closed to general shear failure, is indicated that it is unrelated to normal stress and a number of transverse members. However, if the allowable displacement of reinforced soil wall is considered, it is impossible to apply in design. The test results are compared with bearing resistance evaluations using Prandtl's plastic theory and cylindrical cavity expansion theory. The analysis results are indicated that the bearing resistance by pullout tests is closed to predicted result by Prandtl's plastic theory, which are located between general shear failure and punching shear failure.

• International Journal of Highway Engineering
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• 제7권4호
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• pp.203-210
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• 2005

The penetration and viscosity tests have been used for the evaluation of the aged asphalt binder performance change. The improved test method has been required because the conventional tests could not evaluate the viscoelastic characteristics and the real behaviour of the aged asphalt binder. The conventional test methods using a different short term aged asphalt binder were tested and the test results were expressed as the penetration index and the residual penetration. The oscillatory and rotational mode tests were performed to find out the rheological characteristics of the short term aged asphalt binder in this study. The test results showed that the change of testing frequency, the speed of the vehicle effects the complex modules and phase angles. The creep compliance and shear viscosity also showed the different test results when the short term aged asphalt binders were tested. The rheological behavior should consider when the pavement design is conducted.

• International Journal of Highway Engineering
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• 제11권4호
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• pp.25-31
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• 2009

In general, it is well known fact that the stone mastic asphalt (SMA) pavement has a high resistance against rutting. However, performance of SMA is not well measured by general method used in the laboratory. The objective of this study is to investigate an applicability of deformation strength ($S_D$) for performance estimation of SMA, and to find out the correlation between rut depth and dynamic stability, and $S_D$ of SMA. This study carried out wheel tracking test and Kim-test with optimum asphalt content (OAC) determined by mix design. The results indicated that the $S_D$ of SMA was very poorer than those of dense-graded asphalt mixtures. $S_D$ showed similar WT dynamic stability and rut-depth level. It was found that Kim-test was not reflected higher rutting resistance of SMA like as indirect tensile strength (ITS) test and Marshall stability test. Also, it was revealed that dynamic stability and rut-depth of WT had some problems to estimate rutting resistance of SMA mixtures.

• Tunnel and Underground Space
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• 제25권3호
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• pp.255-263
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• 2015

Explosive blasting is a very useful tool for mining and civil engineering applications. It, however, may cause severe environmental hazards on adjacent structures due to blasting impact. Blast engineers try to make optimum blast design to provide efficient performance and to minimize the environmental impact as well. It requires a pre-assessment of the impacts resulting from the blasting operation in design stage. One of the common procedures is to evaluate the proposed blast pattern through a series of test blasting in the field. Another approach is to evaluate the possible environmental effects using the numerical methods. There are a number of input parameters to be prepared for the numerical analysis. Some of them are well understood, while some are not. This paper presents some results of sensitivity analysis of the basic input parameters in numerical modelling of blasting problems so as to provide sound understanding of the parameters and some guidelines for input preparation.

• Ecology and Resilient Infrastructure
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• 제6권4호
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• pp.208-216
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• 2019

This study investigated design factors and removal efficiencies of a sheet flow channel as natural type water improvement techniques in the stream. The channel was designed considering the design factors, then constructed and monitored in the test bed of the Osan stream's floodplain. Water lever, velocity, discharge, T-P, T-N, and NO₃-N were monitored and the removal efficiencies and design formula were suggested. Overall efficiencies of T-P, T-N, and NO₃-N range 10 - 20%, and they show consistent relations with residence times. Minimum velocity requirement is also suggested from the relation of algae conditions and velocities. Relation formula of residence time and removal efficiency will be applicable in the design and operation process of a sheet flow channel.

• International Journal of Highway Engineering
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• 제5권4호
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• pp.23-35
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• 2003

In this study, compaction evaluating program based on ASTM critria is developed bu analyzing the results of laboratory tests. And the laboratory tests such as compaction test, triaxial test and resonance column test of subgrade soils are performed to develop compaction management methodology at seven test sites. Especially, to figure out chararteristic with changing compactive efforts, the test was carried out at five levels of compactive efforts at each soil sample. Database was set up from the test results. With the methodology using mechanical property - the elastic modulus, the gap between road design and management and road construction management is narrowed. The regression equation of G/$G_{max}$ is proposed at each strain level of subgrade soils according to AASHTO criteria, and the relationship between fundamental properties of soil mass and degree of compaction is derived as well. The development of compaction management and field compaction management method is proposed by the elastic modulus based on mechanical tests.

• Journal of the Korean Geotechnical Society
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• 제29권8호
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• pp.37-51
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• 2013

An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.