• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.31-40
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• 2009

Some road charges toll to finance the cost or to manage traffic congestion. With a growth of PPI projects, toll roads would be increase continuously. Tolls have a considerable influence on user's route choice, and sometimes can affect to the departure time and even to mode choice. For modelling toll roads, user's WTP or VOT has an important role and it is general that VOT is equivalent to the wages of workers. The current way of modelling technique yields various toll price elasticity from low to high. When there exist few alternative routes, unrealistic result that all traffic assigned to some shortest path may occur. The toll price elasticity can be influenced by alternative route and congestion level, but some result shows nearly unrealistic patterns. The model to forecast more realistic toll road demand is very essential for estimating toll revenue, choice of optimal toll level & collecting location and establishing toll charge strategy. This paper reviewed some literatures about toll road modelling and tested case study about the assignment technique with different VOT. The case study shows that using different VOT yields more realistic result than the use of single VOT.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.217-223
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• 2018

This study to search the diagnostic performance of shear wave elastography(SWE) in breast mass and to compare the biopsy result and stiffness obtained from shear wave elastography. Diagnostic breast ultrasonography and SWE were targeted for 157 patients who had breast ultrasonography was diagnosed mass from June 2017 to September 2017. Pathology results of 157 patients showed a benign 92 patients(Age, $44.54{\pm}11.84$) and a malignancy 65 patients(Age, $51.55{\pm}10.54$). Final evaluation, biopsy result, and quantitative SWE result were obtained and compared with each other according to Breast Imaging Reporting and Data System(BI-RADS) of diagnostic breast ultrasonography. Quantitative SWE value and pathologic result showed the highest diagnostic specificity of 83.70% in Emean and sensitivity of 89.23% in Emin. Quantitative SWE result and biopsy result is statistically significant.(p=0.000). The optimal cut-off value for malignant lesions was 66.3 kPa and 63.7 kPa, respectively, for the sensitivity, specificity, high maximum mean elasticity value(Emax) and mean elasticity value(Emean) and this showed the highest diagnostic area under the ROC curve(Az) value compared to other SWE measurement(p=0.000). The addition of SWE to conventional US in breast mass make a increase diagnostic specificity and reduce unnecessary biopsy. Therefore, it is expected that it will be helpful to analyze the breast mass using the above analysis and apparatus.

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.184-191
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• 2009

In the southern part of the Korean Peninsula including Jeju-island, the production amount of domestic cedar has increased gradually. However, their low qualities, expected to be caused by the low density and frequent knots, have restricted their practical utilization as the high value-added products. In this study, it is aimed to look for the new uses of domestic cedar and to examine the applicability for lamination lumbers of structural glued laminated timber (glulam). Above all, machine stress ratings for individual sawn lumbers confirmed that modulus of elasticity (MOE) of cedar lumber was lower than that of other common softwood species in Korea. On the other hand, cedar lumbers have enough stiffness to manufacture the structural glulam in accordance with Korean Industrial Standard (KS). The bonding strength and durability also met the KS limitation. Nevertheless, from the result of bending tests for cedar glulam, it was shown that the modulus of elasticity (MOE) did not meet the KS limitation. Therefore, it was concluded that additional researches were needed for reinforcing the stiffness of cedar glulam.

• Korean Journal of Poultry Science
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• v.16 no.3
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• pp.157-167
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• 1989

Pretreatment of egg white and ion exchange resins was attempted to separate lysozyme from egg white efficiently. Apparent viscosity of egg white could be decreased to 3cp by homogenization for 30 minutes at 2, 000rpm and ultrasonication for 45 minutes. The result of testing adsorption capacity of lysozyme was as follows； CM-Sephadex C-25 ＞Duolite C464＞Amberlite C-50＞Dowex MSC-1＞Amberlite IRC-50＞Amberlite IRC-84. Although CM-Sephadex C-25 showed highest adsorption capacity of lysozyme, egg white could not eluted easily. Duolite Cf64 was selected based on relatively high lysozyme adsorption and good egg white eluting property for separation of egg white lysozyme. Na$^{＋}$ form of Duolite C-464 was most effective on adsorption of Iysozyme. To separate lysozyme from egg white efficiently rinse buffer and eluting solution were selected 0.1M sodium phosphate buffer at pH 6.5 and 10% ammonium sulfate respectively. After separating lysozyme from egg white, foaming power of egg white was decreased to 85.3%. Color of egg white gel was not changed while hardness of egg white gel was decreased by 30% after separating lysozyme. However, elasticity of egg white gel was increased by 13% in lysozyme-separated egg white.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.321-330
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• 2011

Recently, the effects of high temperature and fiber content on the residual mechnical properties of high-strength concrete were experimentally investigated. In this paper, residual mechanical properties of concrete with water to cement (w/c) ratios of 0.55, 0.42 and 0.35 exposed to high temperature are compared with those obtained in fiber reinforced concrete with similar characteristics ranging from 0.05% to 0.20% polypropylene (PP) fiber volume percentage. Also, factors including pre-load levels of 20% and 40% of the maximum load at room temperature are considered. Outbreak time, thermal strain, length change, and mass loss were tested to determine compressive strength, modulus of elasticity, and energy absorption capacity. From the results, in order to prevent the explosive spalling of 50 MPa grade concretes exposed to high temperature, more than 0.05 vol. % of PP fibers is needed. Also, the cross-sectional area of PP fiber can influence the residual mechanical properties and spalling tendency of fiber reinforced concrete exposed to high temperature. Especially, the external loading increases not only the residual mechanical properties of concrete but also the risk of spalling and brittle failure tendency.

• Advances in concrete construction
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• v.3 no.4
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• pp.317-331
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• 2015

This paper presents the effect of different micro-silica (MS) contents of 5, 10 and 15 wt.% as partial replacement of cement on mechanical and durability properties of high volume fly ash - recycled aggregate concretes (HVFA-RAC) containing 50% class F fly ash (FA) and 35% recycled coarse aggregate (RCA) as partial replacement of cement and natural coarse aggregate (NCA), respectively. The measured mechanical and durability properties are compressive strength, indirect tensile strength, elastic modulus, drying shrinkage, water sorptivity and chloride permeability. The effects of different curing ages of 7, 28, 56 and 91 days on above properties are also considered in this study. The results show that the addition of MS up to 10% improved the early age (7 days) strength properties of HVFA-RAC, however, at later ages (e.g. 28-91 days) the above mechanical properties are improved for all MS contents. The 5% MS exhibited the best performance among all MS contents for all mechanical properties of HVFA-RAC. In the case of measured durability properties, mix results are obtained, where 10% and 5% MS exhibited the lowest sorptivity and drying shrinkage, respectively at all ages. However, in the case of chloride ion permeability a decreasing trend is observed with increase in MS contents and curing ages. Strong correlations of indirect tensile strength and modulus of elasticity with square root of compressive strength are also observed in HVFA-RAC. Nevertheless, it is established in this study that MS contributes to the sustainability of HVFA-RAC significantly by improving the mechanical and durability properties of concrete containing 50%less cement and 35% less natural coarse aggregates.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.95-101
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• 2015

Objective : The purpose of this study was to analyze the effects of multisensory exercise on foot pressure sensitivity and balance for the elderly. Method : The subjects were 17 elderly women (11 for the experimental group and 6 for the control group) with a mean age of 83. The subjects all lived in senior residence centers in Seoul. Multisensory exercise was done twice a week for 40 minutes during a 12 week period. Exercise programs were changed every 3 weeks according to the principal of gradual progress of the exercise. In order to train the vision system subjects were asked to open and close their eyes during exercise. When it came to training the vestibular system, subjects stood and walked on high elastic mats with their bare feet. For the somatasensory system subjects always stood and walked with their bare feet. The sub-Metatarsal Pad Elasticity Acquisition Instrument (MPEAI) was used to measure foot pressure sensitivity. MFT Balance test (V1.7) was used to measure anterior / posterior and medial / lateral directional balance. For the statistical analysis the IBM SPSS 21.0 was used to perform Repeatde measured ANOVA and Wilcoxon ranked test. Results : For the multisensory exercise group Hallux (after 6 weeks, 12 weeks), heel (after 6 weeks) and 2nd Metartarsal $40^{\circ}$ (after 6 weeks) pressure sensitivity increased statistically, but the control group didn't change. Also, balance didn't change for the experimental and control group statistically. Conclusion : Exercise with bare feet on a high elastic mat had a partially positive effect on foot sensitivity.

• Applied Biological Chemistry
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• v.33 no.3
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• pp.203-208
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• 1990

The physical characteristics of texture, water holding capacity, color and swelling of soybean curd were studied for 14 varieties of soybeans grown in Korea. The relative water holding capacity, measured by moisture absorption method with using filter paper, was high for Millyang-21. Danyeob and Hwangum, low for Suwon-138, -141 and -142. All of the soybean curd prepared showed negative Sag values, which indicates swelling properties of Tofu as it as released from pressed condition. The most swollen variety was Suwon-138 and the least one was Suwon-142. Generally, soybean curd having high moisture content had low valuss in hardness but no significant relationship was found. Elasticity ud cohesiveness showed a little differences except Suwon-138. Other textural characteristics of fracturability, adhesiveness and gumminess showed a wide range in their values among the varieties.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.20-27
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• 2017

The aim of this paper is to present the modulus of elasticity of $E_L$, $E_R$, $E_T$ along three principal axis of softwood dimension lumber by nondestructive method. Ultrasonic measurement was carried out on defect free wood samples taken by the Japanese Larch, SPF (spruce-pine-fir) and Hem-fir $2{\times}4s$. The ultrasound velocities were measured to calculate young's moduli and it was derived elastic constants for each wood samples using the ultrasound velocities and densities of wood. From the test, $E_L$ was much greater than $E_R$ and $E_T$. $E_R/E_T$ ratios were about 1.3. The high density wood had high young's moduli in three principal axis and the difference in young's moduli between species was greater in transverse direction than longitudinal direction. The anisotropy of the lumber was presented through the calculated elastic moduli and compliances matrix in diagonal term were determined by inverting the stiffness matrix.

• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.2
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• pp.1-8
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• 2014

Fiber reinforced polymeric plastic (FRP) materials have many advantages over conventional structural materials, i.e., high specific strength and stiffness, high corrosion resistance, right weight, etc. Among the various manufacturing methods, pultrusion process is one of the best choices for the mass production of structural plastic members. Since the major reinforcing fibers are placed along the axial direction of the member, this material is usually considered as an orthotropic material. However, pultruded FRP (PFRP) structural members have low modulus of elasticity and are composed of orthotropic thin plate components the members are prone to buckle. Therefore, stability is an important issue in the design of the pultruded FRP structural members. Many researchers have conducted related studies to publish the design method of FRP structures and recently, referred to the previous researches, pre-standard for LRFD of pultruded FRP structures is presented. In this paper, the accuracy and suitability of design equation for the local buckling strength of pultruded FRP I-shape compression members presented by ASCE are estimated. In the estimation, we compared the results obtained by design equation, closed-form solution, and experiments conducted by previous researches.