• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.6
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• pp.665-674
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• 2001

In this paper, a reduced complexity fillet to simultaneously suppress the blocking and ringing artifacts of compressed video sequence is addressed. A new one dimensional regularized function to incorporate the smoothness to its neighboring pixels into the solution is defined, resulting in very low complexity filter The proposed regularization function consists of two sub-functions that combine local data fidelity and local smoothing constraints. The regularization parameters to control the trade-off between the local fidelity to the data and the smoothness are determined by available overhead information in decoder, such as maroc-block type and quantization step size. In addition, the regularization parameters are designed to have the limited range and stored as look-up-table, and therefore, the computational cost to determine the parameters can be reduced. The experimental results show the capability and efficiency of the proposed algorithm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.91-100
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• 2018

The new seismic retrofit system in study propose is the Dual system, which aims to be applied to the seismically vulnerable low-story buildings. The Dual system is composed of existing structure, external retrofit frame and hysteretic steel dampers installed between former two components. The Dual system dissipates the energy by plastic deformation of steel damper caused by relative displacement due to the differences in stiffness, weight, and eigenperiod of each components. The dynamic test with shaking table was performed to verify the seismic performance of the proposed Dual system. As a result of the dynamic test, it is expected that the Dual system will improve the seismic performance due to the reduction of strain of 56% and the damage reduction of 93%, even though the energy is 1.84 times higher than that of the dual system. And the results of the study are presented as basic data of the study for setting the design range of the dual system.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.429-430
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• 2008

We demonstrate coherent x-ray diffraction imaging using table-top x-ray laser at a wavelength of 13.9nm driven by 10-Hz ti:Sapphire laser system at the Advanced Photonics Research Institute in Korea. Since the flux of x-ray photons reaches as high as $10^9$ photons/pulse in a $20{\times}20{\mu}m^2$ field of view, we measured a ingle-pulse diffraction pattern of a micrometer-scale object with high dynamic range of diffraction intensities and successfully reconstructed to the image using phase retrieval algorithm with an oversampling ratio of 1:6. the imaging resolution is $^{\sim}150$ nm, while that is much improved by stacking the many diffraction patterns. This demonstration can be extended to the biological sample with the diffraction limited resolution.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.54-61
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• 2018

Objective: The current study aimed to investigate the accessibility and usability of the disabled person while using the everyday facility. Background: The national laws regulated accommodation of persons with disabilities, but our knowledge on the practical usefulness of the laws and acceptance by the users is still far from complete. Method: Compliance with laws was checked throughout the actual measurement of 87 engineering designs in the facilities of a national university, and the practical usability of the facilities was investigated by in-depth interviews with eight disabled persons. New design solutions were developed by the anthropometric methodology for better accommodation. The target-specific anthropometry database such as sitting knee height with wheelchair was employed. Results: First, the statistic showed that 28.7% of facility designs comply with the law, 29.9% of facility designs doesn't comply with the law, and 41.4% of facility designs doesn't have related law or regulation. Second, the law of table height(71cm in current) can accommodate only 49.3% of wheelchaired population. The following test for 95% accommodation revealed that the table with 80cm high is required. Third, the current law in the door width(90cm) can only accommodate 82.6% of disabled persons, so the new design solution was calculated and suggested that 100cm in the door width is necessary for 99% accommodation of disabled persons. Conclusion: Even with the laws and regulations for the disabilities it was clear that the accessibility and usability of the disabled persons in everyday facilities was still limited. An investigation for the new solutions about a wide range of facilities is necessary for better practical accessibility and usability of the handicapped persons. Application: The results of current study can be a basement of developing a new guideline or regulation of the facility design for the disabled persons.

• Korean Journal of Community Nutrition
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• v.19 no.3
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• pp.274-282
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• 2014

Objectives: The objective of this study was to revise the target pattern in food guidance system for adolescents' balanced menu planning. Methods: The food groups in the target pattern were divided into detailed food items, and intake number were assigned to each food items based on the revised standard food composition table. The validity of revised target pattern was examined. Menu planning according to the revised target pattern was made available to 305 male and female middle school students and the nutritional assessment of the menu plan were carried out using SPSS WIN 12.0. Results: The energy contents, energy contribution ratios of carbohydrate, fat, and protein, and 4 minerals' and 6 vitamins' contents of the revised target pattern were adequate. The average energy contents of the menu planned according to revised target pattern were 400~500 kcal higher than that of the revised target pattern when the revised standard food composition was applied. The energy contribution ratios of fat were 28.9%, close to maximum of acceptable macronutrient distribution range (AMDR) (30%), and that of carbohydrate were 54.5%, lower than minimum of AMDR (55%). The nutrient adequacy ratios (NARs) of calcium and vitamin C were less than 1.0. According to index of nutritional quality (INQ) of food items, kimchi, milk dairy products, and soybean curd were energy efficient source for calcium, kimchi, fruit, vegetable and seaweed were energy efficient source for vitamin C, with INQ of food items were higher or close to 2.0. Kimchi was the best energy efficient source of calcium and vitamin C. Conclusions: Revised target pattern based on the adolescent's foods intake was not good enough for balanced menu planning by adolescents, because what they ate and what they wanted to eat were very much different. Detailed guidance for food selection is necessary in each food items.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.617-623
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• 2007

A novel c-DSDV routing protocol is proposed in clustered mobile ad hoc networks. Clusterheads that manage members in their own cluster construct a higher layer backbone to which the DSDV concept is applied. Each clusterhead maintains its own global routing table by exchanging Update Request (UREQ) messages with its neighboring clusterheads. A number of entries in the table is as small as a number of clusterheads unlike a number of nodes in DSDV Since a UREQ message travels from one clusterhead to all its neighboring clusterheads that are at most 3 hops away, the topology convergence range by each UREQ message is at least 9 times as wide as that of DSDV and CGSR, greatly improving accuracy of routing information. However, overhead in c-DSDV is similar to that of DSDV because only clusterheads initiate UREQ messages. Delivery ratio increases by about 32$\sim$50%.

• Journal of Korean Association for Spatial Structures
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• v.19 no.1
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• pp.117-126
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• 2019

Micro-Electro-Mechanical Systems (MEMS) sensors have been widely used in Structural Health Monitoring due to their convenience and lower costs in comparison to conventional sensors. Triggered measurements are relevant in events such as earthquakes because unlike continuous measurements, they only record the structural response once an event happens. This is more cost effective and it makes the data more manageable because only the required measurements from the event are recorded. The most common method of triggering is amplitude triggering. However, lower input amplitudes (less than 0.1g) cannot be triggered by using this method. In this paper, sound triggering was introduced to allow triggered measurements for lower input amplitude values. The performance of the sound triggering and amplitude triggering were compared by a series of shaking-table tests. It was seen that sound-triggering method has a wider frequency (0.5~10Hz) and amplitude (0.01~1.0g) range of measurements. In addition, the sound triggering method performs better than the amplitude triggering method at lower amplitudes. The performance of the amplitude triggering, in terms of the triggering being simultaneous improves at higher input amplitudes.

• Computers and Concrete
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• v.27 no.2
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• pp.163-173
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• 2021

In this paper, the parameters of haunch height, reinforcement ratio and site condition were evaluated for the influence on the seismic performance of a composite precast fabricated utility tunnel by shaking table test and numerical simulation. The dynamic response laws of acceleration, interlayer displacement and steel strain under unidirectional horizontal seismic excitation were analyzed through four specimens with a similarity ratio of 1:6 in the test. And a numerical model was established and analyzed by the finite element software ABAQUS based on the structure of utility tunnel. The results indicated that composite precast fabricated utility tunnel with the good anti-seismic performance. In a certain range, increasing the height of haunch or the ratio of reinforcement could reduce the influence of seismic wave on the utility tunnel structure, which was beneficial to the structure earthquake resistance. The clay field containing the interlayer of liquefied sandy soil has a certain damping effect on the structure of the utility tunnel, and the displacement response could be reduced by 14.1%. Under the excitation of strong earthquake, the reinforcement strain at the side wall upper end and haunches of the utility tunnel was the biggest, which is the key part of the structure. The experimental results were in good agreement with the fitting results, and the results could provide a reference value for the anti-seismic design and application of composite precast fabricated utility tunnel.

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.655-669
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• 2022

Passive vibration control devices like tuned liquid column dampers (TLCD) not only significantly reduce buildings' vibrations but also can serve as a water storage facility. The recently introduced modified form of TLCD known as tuned liquid column ball damper (TLCBD) suppressed external vibration efficiently compared to traditional TLCD. For excellent performance, the mass ratio of TLCBD should be in the range of 5% to 7%, which does not include the mass of the ball. This additional mass of the ball increases the overall structure mass. Therefore, in this paper, an effort is made to reduce the mass of TLCBD. For this purpose, a new modified version of TLCBD known as tuned liquid column hollow ball damper (TLCHBD) is proposed. The existing mathematical modeling of TLCBD is used for this new damper by updating the numerical values of the mass and mass moment of the ball. Analytically the optimal design parameters are obtained. Numerically the TLCHBD is investigated with a single degree of freedom structure under harmonic and seismic loadings. It is found that TLCHBD performance is similar to TLCBD in both loadings' cases. To validate the numerical results, an experimental study is conducted. The mass of the ball of TLCHBD is reduced by 50% compared to the ball of TLCBD. Both the arrangements are studied with a multi-degree of freedom structure under harmonic and seismic loadings using a shake table. The results of the experimental study confirm the numerical findings. It is found that the performance behavior of both the dampers is almost similar under harmonic and seismic loadings. In short, the TLCHBD is lighter in weight than TLCBD but has a similar vibration suppression ability.

• Smart Structures and Systems
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• v.31 no.1
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• pp.89-100
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• 2023

This paper conducts a parametric study of a new tuned mass damper with pre-strained superelastic SMA helical springs (SMAS-TMD) on the vibration reduction effect. First, a force-displacement relation model of superelastic SMA helical spring is presented based on the multilinear constitutive model of SMA material, and the tension tests of the six SMA springs fabricated are implemented to validate the mechanical model. Then, a dynamic model of a single floor steel frame with the SMAS-TMD damper is set up to simulate the seismic responses of the frame, which are testified by the shaking table tests. The wire diameter, initial coil diameter, number of coils and pre-strain length of SMA springs are extracted to investigate their influences on the seismic response reduction of the frame. The numerical and experimental results show that, under different earthquakes, when the wire diameter, initial coil diameter and number of coils are set to the appropriate values so that the initial elastic stiffness of the SMA spring is between 0.37 and 0.58 times of classic TMD stiffness, the maximum reduction ratios of the proposed damper can reach 40% as the mass ratio is 2.34%. Meanwhile, when the pre-strain length of SMA spring is in a suitable range, the SMAS-TMD damper can also achieve very good vibration reduction performance. The vibration reduction performance of the SMAS-TMD damper is generally equal to or better than that of the classic optimal TMD, and the proposed damper effectively suppresses the detuning phenomena that often occurs in the classic TMD.