• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.606-611
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• 2000

It has been noted that the low frequency absorption coefficient of a porous sample placed in a standing wave tube is affected by the nature of the sample's edge constraint. The edge constraint has the effect of stiffening the solid phase of the sample, which itself can be strongly coupled to the material's fluid phase, and hence the incident sound field, by viscous means at low frequencies. In recent work it has also been shown that such a circumferential constraint causes the low frequency transmission loss of a layer of fibrous material to approach a finite low frequency limit that is proportional to the flow resistance of the layer and which is substantially higher than that of an unconstrained sample of the same material. However, it was also found that the benefit of the circumferential edge constraint was reduced in a transitional frequency range by a shearing resonance of the sample. Here it will be shown that the effect of that resonance can be mitigated or eliminated by adding additional axial and radial constraints running through the sample. It will also be shown that the constraint effect can be modeled closely by using a finite element procedure based on the Biot poroelastic theory. Implications for low frequency barrier design are also discussed.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.601-606
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• 2016

In this study, in order to analyze the low-temperature sintering process of silver and copper nanoparticles, we calculate their melting temperatures and surface melting temperatures with respect to particle size. For this calculation, we introduce the concept of mean-squared displacement of the atom proposed by Shi (1994). Using a parameter defined by the vibrational component of melting entropy, we readily obtained the surface and bulk melting temperatures of copper and silver nanoparticles. We also calculated the absorption cross-section of nanoparticles for variation in the wavelength of light. By using the calculated absorption cross-section of the nanoparticles at the melting temperature, we obtained the laser threshold energy for the sintering process with respect to particle size and wavelength of laser. We found that the absorption cross-section of silver nanoparticles has a resonant peak at a wavelength of close to 350 nm, yielding the lowest threshold energy. We calculated the intensity distribution around the nanoparticles using the finite-difference time-domain method and confirmed the resonant excitation of silver nanoparticles near the wavelength of the resonant peak.

• Wind and Structures
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• v.32 no.5
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• pp.405-421
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• 2021

To gain insight into the wind-induced safety concerns associated with attached tower cranes during the construction of super-tall buildings, a 606 m level frame-core tube super-tall building is selected to investigate the wind-induced vibration response and fragility of an outer-attached tower crane at all stages of construction. The wind velocity time history samples are artificially generated and used to perform dynamic response analyses of the crane to observe the effects of wind velocity and wind direction under its working and non-working resting state. The adverse effects of the relative displacement response at different connection supports are also identified. The wind-resistant fragility curves of the crane are obtained by introducing the concept of incremental dynamic analysis. The results from the investigation indicate that a large relative displacement between the supports can substantially amplify the response of the crane at high levels. Such an effect becomes more serious when the lifting arm is perpendicular to the plane of the connection supports. The flexibility of super-tall buildings should be considered in the design of outer-attached tower cranes, especially for anchorage systems. Fragility analysis can be used to specify the maximum appropriate height of the tower crane for each performance level.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.5
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• pp.596-606
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• 1998

Thermophysical properties and the compressive strength of concrete used in nuclear power plants in Korea were measured. The chemical composition of the concrete was also analyzed. The measured thermophysical properties include the density, the thermal conductivity, the thermal diffusivity and the specific heat for a wide temperature range of 20.deg. C to 1100.deg. C. The chemical composition of Korean concrete is similar to that of US basaltic concrete and the thermophysical properties are strongly temperature dependent. The density, the conductivity and the diffusivity decrease with an increase in temperature, and particularly the conductivity and the diffusivity are a 50-perdent decrease at 900.deg. C as compared with these values at room temperature. The specific heat increases until 500.deg. C, decreases from 700.deg. C to 900 .deg. C, and then increases again when temperature is above 900.deg. C. The measurement beyond 1100.deg. C is not acceptably accurate because the concrete decomposes to a liquid phase from a solid phase at that temperature. The results of this study can be applied, for example, to an analysis of the molten core-concrete interaction (MCCI) phenomenon of concrete structures at high temperature will also require those property data, especially for high temperature ranges.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.120-125
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• 2012

Because ships and offshore structures have very large dimensions and complicated shapes, it is difficult to determine the deformation or internal stress in the structure by simple lab tests. Thus, a rigorous analysis by using the computer simulation technology is essential for obtaining their distortions by considering the entire production process characteristics. The rapid development of computer technology made it possible to analyze the heat transfer phenomena, deformation and phase transformation in the welded joint. For large shell structures, shell elements modeling contributed primarily to this development. But if a welding is done by multi-pass, shell elements whose thickness are unchangeable can hard to describe the local situation. Recently, it was researched how to introduce the imaginary temperature for V grooved multi-layer butt welding in strain-boundary method (a kind of shrinkage methodologies). In the present study, we formulated the imaginary temperature for the double bevel and double V groove by considering the thickness change of each pass through the bead and the thickness directions simultaneously and also demonstrated the feasibility of the formula by applying it to the thermal distortion analysis of the erection process of crane pedestal.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.4
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• pp.597-606
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• 2007

The purpose of this study was to investigate the satisfaction with school foodservice programs by foodservice operation type in middle school and high school students in the Geumsan-Gun area. A total of 530 subjects(250 middle school and 280 high school students) from the Geumsan-Gun area participated from March 15 to March 23, 2004. Questionnaires were used to study dietary habits, activity levels, and current health conditions. The results of the study are summarized as follows. Based on the body mass index(BMI) scores of the students, the high school male BMI scores were significantly different(5%), and they were underweight for their height. The students were primarily dissatisfied with times for meals for school foodservice under direct management and with the quantity of meal for school foodservice under contract. Compared to the middle school female students, the male high school students were dissatisfied with the time for meals and quantity of food. Generally, the students were satisfied with dessert items the most. The food most often wasted was soup. The middle and high school students preferred food services to those under contract.

• Korean Journal of Adult Nursing
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• v.15 no.4
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• pp.596-606
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• 2003

Purpose: The purposes of this study were to develope and evaluate a constipation intervention program for inpatients. Method: To develope this program, Six phases were processed including the organization of team, the analysis of medical chart, the development of tentative constipation intervention program, the test of content validity, the test of clinical validity and the determination of final constipation intervention program. To evaluate the clinical validity of this program, 10 subjects who were in the C University Hospital were selected from March, 2001 to October, 2001. Result: The clinical validity was supplied by the pilot test, showing the potential effect of the program. Based on the validity results the final algorithm and the form of nursing record for this program which consist of the 3-step assessments and the intervention protocol were presented in this study. Conclusion: The advantage of this program is being able to assess and manage constipation simultaneously and is especially effective to patients who are at risk for developing constipation during their admission. Further study needs are also necessary to evaluate the effect of this program on the self-symptom of constipation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.8
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• pp.599-606
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• 2007

An experimental study was performed to measure a ice concentration of ice slurry flowing in a pipe in a real time. In the present paper, we suggested a measuring method by a refractive index and compared it to other methods by a freezing point and a density. To measure the refractive index of the solution, ice particles in the ice slurry should be completely removed and a hydro-cyclone was introduced instead of a mesh. The measuring method through the refractive index coincided with the density method using the real-time solution density within ${\pm}5%$ error range, having the error range less than the other two methods. In the other hand, the measuring method through the density has a good resolution, but the result using the initial density of the solution was different more than 10% error from that using the real-time density. And it has an error range 1.5 times greater than the method through the refractive index.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.599-606
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• 2017

In this paper, the automatic control system of the stroller brake was designed and manufactured to reduce the safety accident of the stroller. The ultrasonic sensors are used to determine whether the handle of the driver's hand is touching or not, and the gyro sensor is designed to detect the current tilt of the baby carriage. If the next driver's hand is not recognized and the tilt exceeds a certain angle, the servo motor is activated and the hydraulic brake is operated to prevent the accident on the downhill road. Finally, in this paper, a smart phone-based application was developed to make the remote control of the brake possible.

• Journal of Agricultural Extension & Community Development
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• v.17 no.3
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• pp.587-606
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• 2010

Theme trail construction should be changed from existing form which connects line to line, or point to line. It should be developed into area form. The project of Trail construction must be converted in area form. The aggregate of the points which is a base element of walk is a line, and the harmonious connection of various line is the area. The close relationship with points and lines is important to operate the project of trail construction in area form effectively. Subject of the project of Theme trail construction of area form must become the village residents which are being contiguous in trail. They must operate management and about trail. The project of Trail construction of area form the plan making is established and if the subjects which, will operate and manage that place are decided upon according to theme must construct the trail of the wide area concept which connects the trail of that trail and neighborhood. If becomes like that local resident and the citizen will be able to coexist with mediation of Trail. If the project of Trail construction of village resident leading is propelled applying rural amenity resources in a way, the trail model which one phases advances could be presented for ecological, economical and cultural.