• Ocean Systems Engineering
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• 제8권1호
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• pp.21-32
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• 2018

Due to the escalation in hydrocarbon consumption, the offshore industry is now looking for advanced technology to be employed for deep sea exploration. Riser system is an integral part of floating structure used for such oil and gas extraction from deep water offering a system of drill twines and production tubing to spread the exploration well towards the ocean bed. Thus, the marine risers need to be precisely employed. The incorporation of the strengthening material, fiber reinforced polymer (FRP) for deep and ultra-deep water riser has drawn extensive curiosity in offshore engineering as it might offer potential weight savings and improved durability. The design for FRP strengthening involves the local design for critical loads along with the global analysis under all possible nonlinearities and imposed loadings such as platform motion, gravity, buoyancy, wave force, hydrostatic pressure, current etc. for computing and evaluating critical situations. Finite element package, ABAQUS/AQUA is the competent tool to analyze the static and dynamic responses under the offshore hydrodynamic loads. The necessities in design and operating conditions are studied. The study includes describing the methodology, procedure of analysis and the local design of composite riser. The responses and fatigue damage characteristics of the risers are explored for the effects of FRP strengthening. A detail assessment on the technical expansion of strengthening riser has been outlined comprising the inquiry on its behavior. The enquiry exemplifies the strengthening of riser as very potential idea and suitable in marine structures to explore oil and gas in deep sea.

• 한국산학기술학회논문지
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• 제8권1호
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• pp.151-155
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• 2007

사과 절편에 레몬, 귤, 오렌지, 파인애플 그리고 루바브 주스로 전 처리한 후 $4^{\circ}C$에서 저장하면서 갈변억제 효과를 측정한 결과 루바브 주스로 처리한 경우 L값 (0.47) 및 E값의(1.8) 변화가 매우 낮아 처리구 중에 가장 우수한 갈변 억제 효과를 보였다. 루바브 주스의 갈변 억제력은 원액을 2배 희석하더라도 저장 6일 정도까지 효과적으로 갈변이 억제되었다. 투과성 ($4{\mu}m$ LDPE) 및 차단성 포장재($65{\mu}m$ Nylon/PE 복합필름)에 따른 사과 절편의 갈변 억제 효과는 최대 저장 기간 7일 동안 갈변 억제력의 유의성 차이를 볼 수 없었다. 기체조성을 달리하여 포장한 경우에는 진공감압 (0.1atm) 및 고산소(70% $O_2$) 포장보다는 질소 충진 (100% $N_2$) 포장의 경우가 갈변억제력이 뛰어났다.

• 소성∙가공
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• 제13권7호
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• pp.635-641
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• 2004

Today the specific outputs of modern supercharger DI diesel engine for passenger cars reach values exceeding 50kw/1. By development of the articulated piston, specific output of up to 70kw/1 are sought. In doing so, peak cylinder pressure increases from the current 14-16MPa to 18-20MPa. The Articulated piston was composed Al cast skirt part and steel forged crown part. We have the target fer the design of forging process and die of the steel forged crown part. The design parameters of the forging process of the piston were obtained by the forging industry experiences and our experimental data and analysis result of finite element simulation. Especially, the design parameter of preform in blocker die was decided by finite element simulation using numerical package DEFROM3D. And also we can verify the design parameter by conducting visio-plasticity test using plasticine material. When we compared the results of analysis and experiment, a metal flow and load curve showed good agreement. Through this research, we could design optimal preform shape of articulated piston for this supercharged DI diesel engine.

• Journal of Welding and Joining
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• 제10권3호
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• pp.54-62
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• 1992

Large steel water pipes are joined prevalently by bell and method and welded at inside and outside of lapped parts. According to the Korean Standard(KS) for fabrication of water pipes, the weldments are designed to have the length of leg which is same as or larger than the thickness of the pipe. It is recently pointed out that the standard size of weldments is too large, which results in an excessive consumption of material and labor. In this study, several cases of weldments having different sizes were investigated to reduce the length of leg to the effective size. For each case, the analysis of stresses was carried out to evaluate the safety of the welded pipes by using a package program, ANSYS, under the consideration of the loading condition of water pipes which includes the soil pressure on the pipe, the load over the road, and temperature change of the pipe. The results of this study revealed that the weldment which has the length of leg of the size over 0.7*thickness of the pipe could provide a stress level below the yield strength. Especially when the length of leg is 85% of the wall thickness, the maximum equivalent stress is only slightly higher than that of the leg of fillet of the size of 1.0*pipe thickness.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3528-3542
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• 2021

A detailed geometrical model of a Krško reactor core was developed using a Monte Carlo neutron transport code MCNP. The main goal of developing an MCNP core model is for it to be used in future research focused on ex-core calculations. A script called McCord was developed to generate MCNP input for an arbitrary fuel cycle configuration from the diffusion based core design package CORD-2, taking advantage of already available material and temperature data obtained in the nuclear core design process. The core model was used to calculate 3D power density profile inside the core. The applicability of the calculated power density distributions was tested by comparison to the CORD-2 calculations, which is regularly used for the nuclear core design calculation verification of the Krško core. For the hot zero power and hot full power states differences between MCNP and CORD-2 in the radial power density profile were <3%. When studying axial power density profiles the differences in axial offset were less than 2.3% for hot full power condition. To further confirm the applicability of the developed model, the measurements with in-core neutron detectors were compared to the calculations, where differences of 5% were observed.

• 한국포장학회지
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• 제24권3호
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• pp.167-180
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• 2018

Interest in the use of smart packaging systems for food products has increased in recent years. Therefore, food researchers are focusing on the development of new indicator based smart packaging technologies by using anthocyanin-based natural dye. Anthocyanins are one of the plant constituents known as flavonoids and responsible for the bright and attractive orange, red, purple, and blue colors of most fruits, vegetables, flowers, and some cereal grains. Indicators of natural dyes such as anthocyanins could express the quality and shelf life of perishable food products. However, the sensitivity and stability for their use in smart food packaging should be established to reach the market proposals. This review article focuses on recent studies related to use of natural dyes based on anthocyanin for smart food packaging applications. This study offers valuable insight that may be useful for identifying trends in the commercialization of natural dyes or for identifying new research areas. This review also provides food and packaging scientists with a thorough understanding of the benefits of anthocyanin-based natural dyes for shelf life indicator when applied to package material specific foods and hence can assist in accelerating commercial adoption.

• 식품보건융합연구
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• 제7권3호
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• pp.25-32
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• 2021

This study examined the effects of kinesio taping on recovery from fatigue induced by an exercise of concentric contraction using an isokinetic machine. The fatigue was introduced by a mode of exercise at 60°/sec, 50 repetitions for three sessions. The changes of blood ammonia, lactate, LDH, and CK as a marker of fatigue were monitored. Eight healthy collegiate students participated in two experiments; 1) kinesio taping application condition and 2) no kinesio taping application condition. Before experiments, their physical characteristics were measured. For the experiment, blood samples were taken before and immediately after exercise, and 24hr as well as 72hr of recovery period. Window SPSS package 12.0 version was used and one-way ANOVA with repeated measures were employed. The results were as follows. 1) Blood ammonia tended to reduce along the recovery, but no differences between conditions were noticed. 2) Blood lactate tended to reduce during the recovery period, but differences between conditions were not noticed. 3) The LDH was not different between conditions and CK tended to reduce during the recovery period, but differences between conditions were not noticed. Based on the results, kinesio taping did not influence on recovery phase of blood ammonia, lactate concentration, LDH, and CK.

• Coupled systems mechanics
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• 제11권4호
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• pp.285-295
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• 2022

Laminated composite plates are utilized extensively in different fields of construction and industry thanks to their advantages such as high stiffness-to-weight ratio. Additionally, they are characterized by their directional properties that permit the designer to optimize their stiffness for specific applications. This paper presents a numerical analysis and optimization study of plates made of composite subjected to low velocity impact. The main aim is to identify the optimum fiber orientations of the composite plates that resist low velocity impact load. First, a three-dimensional finite element model is built using LS DYNA computer software package to perform the impact analyses. The composite plate has been modeled using solid elements. The failure criteria of Tsai-Wu's criterion have been used to control the strength of the composite material. A good agreement has been found between the predicted numerical results and experimental results in the literature which validate the finite element model. Then, an Adaptive Simulated Annealing (ASA) has been used to optimize the response of impacted composite laminate where its objective is to maximize the safety factor by varying the ply angles. The results show that the ASA is robust in the sense that it is capable of predicting the best optimal designs.

• Computers and Concrete
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• 제29권4호
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• pp.247-253
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• 2022

In this study, the problem of discontinuous contact in two functionally graded (FG) layers resting on a rigid plane and loaded by two rigid blocks is solved by the finite element method (FEM). Separate analyzes are made for the cases where the top surfaces of the problem layers are metal, the bottom surfaces are ceramic and the top surfaces are ceramic and the bottom surfaces are metal. For the problem, it is accepted that all surfaces are frictionless. A two-dimensional FEM analysis of the problem is made by using a special macro added to the ANSYS package program The solution of this study, which has no analytical solution in the literature, is given with FEM. Analyzes are made by loading different Q and P loads on the blocks. The normal stress (σy) distributions at the interfaces of FG layers and between the substrate and the rigid plane interface are obtained. In addition, the starting and ending points of the separations between these surfaces are determined. The normal stresses (σx, σy) and shear stresses (τxy) at the point of separation are obtained along the depth. The results obtained are shown in graphics and tables. With this method, effective results are obtained in a very short time. In addition, analytically complex and long problems can be solved with this method.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.755-764
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• 2023

The article examines the impact response of the sandwich beam furnished by a novel bilayer core as inspired by the woodpecker's head architecture under different repeatedly exerted low-velocity impact loadings by employing the finite element package, ABAQUS. The sandwich beam forms four essential parts comprising bottom and top carbon fiber reinforced polymer laminates encasing bilayer core made of laterally arched solid hot melt adhesive material and aluminum honeycomb. Impact loadings are implemented repeatedly with a steel hemisphere impactor for various impact energies, 7.28 J, 9.74 J, and 12.63 J. Essentially, the commonly concentrated stresses at the impact region are regulated away by the arched core in all considered cases thus reducing the threat of failure. The sandwich beam can resist up to 5 continual impacts at 7.28 J and 9.74 J but only up to 3 times repeated loads at 12.63 J before visible failure is noticed. In the examination of several key impact performance indicators under numerous loading cases, the proposed beam demonstrates favorably up to 1.3-11.2 higher impact resistance efficacies compared to existing designs, therefore displaying an improvement in repeated impact resistance of the new design.