• Korean journal of applied entomology
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• v.62 no.4
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• pp.245-253
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• 2023

A control technique using mass-trapping was developed against thrips infesting hot peppers cultivating in greenhouses. It was essential to develop effective lure(s) attracting thrips for the control technique. Especially, mass-trapping using aggregation pheromone (AP) of the thrips was not much effective in open field cultivating hot peppers. This study aimed to develop a new lure to enhance the attractiveness of AP-based mass-trapping. In addition, this study was designed to investigate the decrease of attractiveness of the AP-based mass-trapping in the open field conditions. Methyl isonicotinate (MIN) as a new lure was assessed by the laboratory olfactometry and showed its attractiveness to thrips and its mixture effect with AP to attract the thrips. These results led us to test the AP+MIN mixture in the open field conditions cultivating hot peppers. The mixture significantly enhanced the mass-trapping efficacy in the open field conditions. Especially, the significant increase of the captured numbers was found in the western flower thrips, Frankliniella occidentalis. Furthermore, the increase of the AP concentration in the mass-trapping significantly increased the captured numbers in F. occidentalis and other thrips occurring in the hot pepper field. This study demonstrated the difference in the AP-based mass-trapping efficacy of the thrips between greenhouse and open field conditions. It also showed the increase of mass-trapping efficacy by increasing AP concentration in the trap. Especially, this study proposes a high efficient mass-trapping technology by the addition of MIN to AP especially against F. occidentalis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.403-410
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• 2009

In this paper, damping coefficients and effective masses of tuned liquid-type column dampers were quantitatively evaluated based on experimental results by using system identification technique. First, shaking table tests were performed for two types of tuned liquid-type column dampers. Then, the dynamic characteristics of dampers used in this study were experimentally grasped from harmonic wave excitation testing results of the dampers with various water level. Finally, damping ratios and effective masses of the dampers with varying water level were quantitatively evaluated from minimizing the errors between numerical and experimental results. It was confirmed from system identification results that damping ratio and effective mass are decreased as the water level of dampers is increased.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1230-1236
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• 2016

This study aims to determine the effect of fly ash with a high replacing ratio of clay on the radiation shielding properties of bricks. Some interaction parameters (mass attenuation coefficients, half value layer, effective atomic number, effective electron density, and absorption efficiency) of clay fly ash bricks were measured with a NaI(Tl) detector at 661.6 keV, 1,173.2 keV, and 1,332.5 keV. For the investigation of their shielding behavior, fly ash bricks were molded using an admixture to clay. A narrow beam transmission geometry condition was used for the measurements. The measured values of these parameters were found in good agreement with the theoretical calculations. The elemental compositions of the clay fly ash bricks were analyzed by using an energy dispersive X-ray fluorescence spectrometer. At selected energies the values of the effective atomic numbers and effective electron densities showed a very modest variation with the composition of the fly ash. This seems to be due to the similarity of their elemental compositions. The obtained results were also compared with concrete, in order to study the effect of fly ash content on the radiation shielding properties of clay fly ash bricks. The clay fly ash bricks showed good shielding properties for moderate energy gamma rays. Therefore, these bricks are feasible and eco-friendly compared with traditional clay bricks used for construction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.20-27
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• 2021

The effective surface of lens was studied for injection molding process and to enable mass production of f-theta lens, which is the primary component of laser printers and laser scanning systems. Injection molding is an optimal method if f-theta lens is frequently used for the mass production of plastic lenses as an aspherical lens that requires ultra-precision. A uniform injection molding system should be maintained to produce high quality lenses. Additionally, to maintain these injection molding systems, various factors such as pressure, speed, temperature, mold and cooling should be considered. However, a lens with the optical characteristics of an f-theta lens can be obtained. The effects of melting and cooling of plastic resin on the effective surface of f-theta lenses and the numerous factors that affect the injection molding process were studied.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.51-73
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• 2014

A three-dimensional finite element model for the Jiashao Bridge, the longest multi-span cable-stayed bridge in the world, is established using the commercial software package ANSYS. Dynamic characteristics of the bridge are analyzed and the effects of structural system measures including the rigid hinge, auxiliary piers and longitudinal constraints between the girders and side towers on the dynamic properties including modal frequency, mode shape and effective mass are studied by referring to the Jiashao Bridge. The analysis results reveal that: (i) the installation of the rigid hinge significantly reduces the modal frequency of the first symmetric lateral bending mode of bridge deck. Moreover, the rigid hinge significantly changes the mode shape and effective mass of the first symmetric torsional mode of bridge deck; (ii) the layout of the auxiliary piers in the side-spans has a limited effect on changing the modal frequencies, mode shapes and effective masses of global vibration modes; (iii) the employment of the longitudinal constraints significantly increases the modal frequencies of the vertical bending modes and lateral bending modes of bridge deck and have significant effects on changing the mode shapes of vertical bending modes and lateral bending modes of bridge deck. Moreover, the effective mass of the first anti-symmetric vertical bending of bridge deck in the longitudinal direction of the fully floating system is significantly larger than that of the partially constrained system and fully constrained system. The results obtained indicate that the structural system measures of the multi-span cable-stayed bridge have a great effect on the dynamic properties, which deserves special attention for seismic design and wind-resistant design of the multi-span cable-stayed bridge.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.49-58
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• 1998

On the stability of the Timoshenko cantilever column subjected of a compressive follower force, the influences of the moment of inertia of the tip mass at the free end and the characteristics of a translational spring at the free end of the column are studied. The equations of motion and boundary conditions of system are estabilished by using the d'Alembert virtual work of principle. On the evaluation of stability of the column, the effect of the shear deformation and rotatory inertia is considered in calculation. The moment of inertia of the tip mass at the free end of the column is changed by adjusting the distance c, from the free end of the column to the tip mass center. The free end of the column is supported elastically by a translational spring. For the maintenance of the good stability of the column, it is also proved that the constant of the translational spring at the free end must be very large for the case without a tip mass while it must be small for the case with a tip mass. Therefore, it is found that the shape of the tip mass and the characteristic of the spring at the free end are very effective elements for the stability of the column when the columns subjected to a compressive follower force are designed.

• Journal of Biomedical Engineering Research
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• v.30 no.2
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• pp.153-161
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• 2009

Mammogram is one of the important techniques for mass detection, which is the early diagnosis stage of a breast cancer. Especially, the CAD(Computer Aided Diagnosis) using mammogram improves the working performance of radiologists as it offers an effective mass detection. There are two types of CAD systems using mammogram; automatic and semi-automatic CAD systems. However, the automatic segmentation is limited in performance due to the difficulty of obtaining an accurate segmentation since mass occurs in the dense areas of the breast tissue and has smoother boundaries. Semi-automatic CAD systems overcome these limitations, however, they also have problems including high FP (False Positive) rate and a large amount of training data required for training a classifier. The proposed system which overcomes the aforementioned problems to detect mass is composed of the suspected area selection, the level set segmentation and SVM (Support Vector Machine) classification. To assess the efficacy of the system, 60 test images from the FFDM (Full-Field Digital Mammography) are analyzed and compared with the previous semi-automatic system, which uses the ANN classifier. The experimental results of the proposed system indicate higher accuracy of detecting mass in comparison to the previous systems.

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.778-787
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• 1996

The purpose of present study was to assess the change of bone mineral density(BMD) and the influences of anthroopometric indices and body composition on BMD in Korean women in Taegu. Subjects were 242 healthy female in the range of 7-67 years old, were divided into 4 age groups in order to assess the influence o factors on BMD according to age. Body composition and BMD measurements of lumbar spine, femur(neck, ward's triangle, trochanter) and total body were performed by dual energy X-ray absorptiometry. The analysis indicated that BMD of most region was positively related to body weight, BMI in all groups 4(50-67years), and closely related to femurs than lumbar spine. This study found correlations between BMD and both total fat body mass and total lean body mass in group 1, 2, 3, and correlations between BMD and only total fat body mass and in group 4. But on regression models the most significant prediction of BMD throughout the skeleton was total lean body mass in group 1(7-16years)and 2(17-34years, and total fat body mass in group 3 and 4. It is concluded that the our data can be used to screen early women of low bone mass. This study confirms that one of the most effective way to prevent osteoporosis and the fractures is to maximize peak bone mass in early life and to minimize bone loss through maintaining adequate weight.

• Wind and Structures
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• v.2 no.4
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• pp.267-284
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• 1999

Multiple tuned mass dampers are proposed to suppress the vertical and torsional buffeting and to increase the aerodynamic stability of long-span bridges. Each damper has vertical and torsional frequencies, which are tuned to the corresponding frequencies of the structural modes to suppress the resonant effects. These proposed dampers maintain the advantage of traditional multiple mass dampers, but have the added capability of simultaneously controlling vertical and torsional buffeting responses. The aerodynamic coupling is incorporated into the formulations, allowing this model to effectively increase the critical speed of a bridge for either single-degree-of-freedom flutter or coupled flutter. The reduction of dynamic response and the increase of the critical speed through the attachment of the proposed dampers to the bridge are also discussed. Through a parametric analysis, the characteristics of the multiple tuned mass dampers are studied and the design parameters - including mass, damping, frequency bandwidth, and total number of dampers - are proposed. The results indicate that the proposed dampers effectively suppress the vertical and the torsional buffeting and increase the structural stability. Moreover, these tuned mass dampers, designed within the recommended parameters, are not only more effective but also more robust than a single TMD against wind-induced vibration.

• Tunnel and Underground Space
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• v.6 no.4
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• pp.306-315
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• 1996

This paper presents an application of the TDR(Time Domain Reflectometry) to the monitoring of the deformation of rock mass with grouted coaxial cables through laboratory tests. The grouted cable can easily deform together with the rock mass movements, and the deformed cable loses its original capacitance and the reflected waveform produced along the deformed cable consequently represents a change of voltage pulse. Therefore, it is possible to monitor the deformation of rock mass by measuring the changes in these reflection signatures. Shear test of the cemented mortar containing a specimen of coaxial cable showed that the shear deformation correlated linearly with the reflection coefficient, so the TDR was effective to monitor the displacement of the rock mass. Bending test were carried out in order to determine the influence of the crooked cables on the monitoring of rock mass movements. Controlled cirmping and shearing test upon a cable of 50 m long, 12.7 mm diameter showed not only the fact that the reflection amplitudes decreased as the cable length increased but also the proper crimping depth, width and interval between two adjacent crimps. Two coaxial cables-one 100 m long and other 175m long-were installed and grouted into the separate boreholes drilled in a sedimentary formation. The behavior of the cable was monitored with metallic TDR cable tester to measure rock mass deformation based on the interpretative techniques developed through laboratory tests.