• Journal of the Korean Wood Science and Technology
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• v.16 no.1
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• pp.55-61
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• 1988

목재(木材)의 응력(應力)과 변형(變形)에 미치는 함수율 및 온도변화의 효과를 유한요소(有限要素) 분석법에 의해 측정하였다. 목재는 춘재(春材) 및 추재(秋材)를 나타내는 층구조(層構造)의 원통형(圓筒形)으로 모델화 하였으며, 선형적(線形的) 탄성체(彈性體) 그리고 원통형(圓筒形) 이력성(異方性) 재료로 가정하였다. 경단면(徑斷面)에서의 변형(變形)은 함수율 및 온도와 밀접한 관매가 인정되었으며, 최대(最大)의 압축응력(壓縮應力)은 최내층(最內層)인 만재층(晩材層)에서 일어났다. 또한 최대의 촉단면응력(觸斷面應力)은 춘재부(春材部)의 최내층(最內層)에서 일어났다. 경단(徑斷) 방향(方向)과 촉단방향(觸斷方向)의 응력간(應力間)의 차이는 외층(外層)에서 가장 크게 나타났으며 이와같은 응력(應力)의 차이가 변형(變形)을 일으키는 주요인(主要因)임이 밝혀졌다.

• Korean Journal of Agricultural Science
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• v.13 no.1
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• pp.113-122
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• 1986

In order to promote mechanization of corn harvesting in Korea, this study was conducted to find out the effect of moisture content on compressive properties such as force, deformation, energy and modulus of stiffness to the bioyield and the rupture point for Korean corn kernel. In this study, the loading positions of corn were flat, edge, longitude and the moisture contents were about 13, 17, 21, 25% in wet basis. The compression test was carreied out with flat plate by use of dynamic straingage for three varieties of Korean corn under quasi-static force when the loading rate was 1.125mm/min. The results of this study are summarized as follows; 1. When the moisture content of corn ranged from 12.5 to 24.5 percent, at flat position, the bioyied force was in the range of 13.63-26.73 kg and the maximum compressive strength was in the range of 21.55-47.65kg. Their values were reached minimum at about 17% and maximum at about 21% moisture content. The bioyield force was in the range of 13.58-6.70kg at edge position and the maximum compressive strength which was 16.42 to 7.82kg at edge position was lower than that which was 18.55-9.05kg at longitudinal position. 2. Deformation of corn varied from 0.43 to 1.37 mm at bioyield point and from 0.70 to 2.66mm at rupture point between 12.5 to 24.5% moisture content. As the moisture content increased, deformation was increased. 3. The moduli of resilience and toughness of corn ranged from 2.60 to 8.57kg. mm and from 6.41 to 34.36kg. mm when the moisture content ranged from 12.5 to 24.5 percent, respectively. As the moisture content increased, the modulus of toughness was increased at edge position and decreased at longitudinal position. And their values were equal each other at 22-23% moisture content. 4. The modulus of stiffness was decreased with increase in the moisture content. Its values ranged from 32.07 to 5.86 kg/mm at edge position and from 42.12 to 18.68kg/mm at flat position, respectively. Also, the values of Suweon 19 were higher than those of Buyeo. 5. It was considered that the compressive properties of corn at flat position were more important on the design data for corn harvesting and processing machinery than those of edge or longitudinal position. Also, grinding energy would be minimized when a corn was processed between about 12.5 to 17% moisture content and corn damage would be reduced when a corn was handled between about 19 to 24% moisture content in wet basis.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.265-270
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• 2022

The purpose of this study is to derive the damage weak part of the elastic rail fastening system for concrete tracks (System 300-1). In the concrete tracks, the elastic rail fastening system sticks the rail and the sleeper and reacts all the time when the train is running. Among the components of the rail fastening system, the resilience pad and tension clamp were fatigue members and were constantly deformed in response to compressive and uplift forces. In this study, the residual deformation characteristics of the tension clamp according to the period of use were analyzed using by specimens taken on site in the same section for 6, 11, and 16 years on the serviced urban transit. In addition, the damage mechanisms for each component were derived based on finite element analysis. As a result of the numerical analysis, the stress (strain) of each part of the tension clamp according to the external force from the applied clamping force was analyzed to derive the damaged weak part of the tension clamp.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.160-164
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• 1992

Cooking, texture and sensory properties of sweet potato Tangmyon (starch noodle), common Tangmyon (50% sweet potato starch+50% corn starch) and corn Tangmyon were evaluated. The weight gain of Tangmyon showed a linear relationship with the square root of cooking time, in which the common Tangmyon showed the highest value. The solid loss during cooking was the highest in common Tangmyon followed by corn Tangmyon. The sweet potato Tangmyon showed the highest value for compression strength and stretching ratio, but lowest value for elongation elastic modulus. At the same compression strength, corn Tangmyon had the highest tensile strength and sweet potato Tangmyon the lowest value. Sweet potato Tangmyon showed the highest sensory scores of gloss, clarity, adhesiveness, gumminess, extensibility and overall desirability, and corn Tangmyon the lowest scores. Except adhesiveness (by appearance) and the gumminess of common and corn Tangmyon, significant differences (p<0.05) were observed for other sensory properties among samples.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.35-43
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• 2023

In this study, the mechanical properties of concrete mixed with non-sintered hwangto(NHT) as an alternate material for cement were evaluated, and the compressive strength prediction equation of concrete based on ultrasonic pulse velocity analysis was proposed. Cement replacement rates for mixed NHT were set to 0, 15, and 30%, and design compressive strength was set to 30 and 45MPa to evaluate the effect on the amount of cement and NHT powder. The mechanical properties items analyzed were compressive strength, ultrasonic pulse velocity, and elastic modulus, and were measured on days 1, 3, 7, and 28. As the replacement rate of NHT increased, the mechanical properties tended to decrease. In addition, as a result of analyzing the correlation between compressive strength and ultrasonic pulse velocity, the correlation coefficient(R²) showed a high relationship(R²=0.95) on concrete mixed with NHT.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.72-78
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• 2008

In this study, advanced (fluid-structure interaction (FSI)) analysis system has been developed in order to predict turbine cascade performance with blade deformation effect due to aerodynamic loads. Intereference effects due to the relative movement of the rotor cascade with respect to the stator cascade are also considered. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation k-ω SST turbulence models are solved to accurately predict fluid dynamic loads considering flow separation effects. A fully implicit time marching scheme based on the (coupled Newmark time-integration method) with high artificial damping is efficiently used to compute the complex fluid-structure interaction problem. Predicted aerodynamic performance considering structural deformation effect of the blade shows somewhat different results compared to the case of rigid blade model. Cascade performance evaluations for different elastic axis positions are importantly presented and its aeroelastic effects are investigated.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.551-558
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• 2011

The effect of the maximum aggregate size and substitution rate of natural sand on the mechanical properties of concrete is evaluated using 15 lightweight aggregate concrete mixes. For mechanical properties of concrete, compressive strength increase with respect to age, tensile resistance, elastic modulus, rupture modulus, and stress-strain relationship were measured. The experimental data were compared with the design equations specified in ACI 318-08, EC2, and/or CEB-FIP code provisions and empirical equations proposed by Slate et al., Yang et al., and Wang et al. The test results showed that compressive strength of lightweight concrete decreased with increase in maximum aggregate size and amount of lightweight fine aggregates. The parameters to predict the compressive strength development could be empirically formulated as a function of specific gravity of coarse aggregates and substitution rate of natural sand. The measured rupture modulus and tensile strength of concrete were commonly less than the prediction values obtained from code provisions or empirical equations, which can be attributed to the tensile resistance of lightweight aggregate concrete being significantly affected by its density as well as compressive strength.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.437-445
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• 2016

Recently, polyurethane foam has been used in various industry fields to preserve temperature environment of structures, and a wide range of loads from the static to the dynamic are imposed on the material during a life period. The biggest characteristic of polyurethane foam is porosity as being polymeric material, and it is generally known that insulation performance of the material strongly depends on internal void size. In addition, polyurethane foam's mechanical behavior has high dependence on strain rate and temperature as well as being highly non-linear ductile for compression. In the non-linear compressive behavior, volume fraction of voids and elastic modulus decrease as strain increases. Therefore, in this study, temperature-dependent viscoplastic-damage constitutive model was developed to describe the non-linear compressive behavior with the aforementioned features of polyurethane foam.

• The Journal of Engineering Geology
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• v.6 no.1
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• pp.23-31
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• 1996

A stress redistribution process in ground support system is mpdeled taking into consideration of load transfer mechanism of unbalanced load within shotcrete in a rock cavern constructed by NATM. The corresponding analysis model for ground support system is proposed and the elastic behavior of the shotcrete is studied. The effect on the support system due to variation of several design parameters is analysed with the proposed model. The suggested model yields considerably reduced maximum compressive stresses in shotcrete. Both the pressure coefficient in horizontal direction and the elastic modulus of rock mass govern overall responses, whereas the variation of the properties in support system shows a little difference in system responses. Interaction equations for evaluating safety factors for structural members are suggested. The result of this study can be used in the structural safety assessment of underground structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.89-95
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• 1989

In this study, it is attempted to examine (1) the residual deformation and elastic deformation induced from the repeated loads (up to the maximum of 100,000 times) on fully compacted soil specimen, the relation between stress and strain by performing the unconfined compressive test, after repeated loads and (2) the effect of water content, dry density, number of cycle, repeated loads, etc. on the effect of the stress-strain relation. The rate of deformation caused by repeated loads greatly depends on to the condition whether the water content is above or below the plastic limit. It is possible to estimate the initial tangent modulus of soil by means of modulus of elastic deformation obtained by putting repeated loads on the clay soil.