• The Journal of the Acoustical Society of Korea
• /
• v.39 no.4
• /
• pp.270-278
• /
• 2020

In this paper, sound transmission of Micro-Perforated Plates (MPPs) installed in an impedance tube with a circular cross-section is described using an analytic method. Vibration of the plates is expressed in terms of an infinite series of modal functions, where modal function in the radial direction is given by the Bessel function. Under the plane wave assumption, a low frequency approximation is derived, and a formula for the sound transmission coefficient of multi-layered MPPs is presented using the transfer matrix method. The Sound Transmission Losses (STLs) of single and double MPPs are computed using the proposed method and compared with those done by the Finite Element Method (FEM), which shows an excellent agreement. As the perforation increases, the STL is degraded, since the STL becomes dominated by the perforation ratio rather than by vibration of the plate. The STL shows dips at natural frequencies as well as at the mass-spring-mass resonance frequency. The proposed model for the STL prediction in this study can be applied to an arbitrary number of MPPs, where each MPP may or may not have a perforation.

• Journal of Embryo Transfer
• /
• v.29 no.3
• /
• pp.207-219
• /
• 2014

Three-dimensional (3D) culture system is useful technique for study of in vivo environment and it was used various experiments. This study was investigated to establish of embryo co-culture system and changes of PAs activity in 3D cultured endometrial cells of pigs. In results, growth of stromal cells into gel matrix were detected only with endometrial and myometrial cells. The most rapid growth of stromal cells were confirmed in $2.5{\times}10^5cells/ml$ and gel matrix containing 15% FBS. Expression of urokinase-PA (uPA) after treatment of hCG (0.5, 1.0, 1.5 and 2.0 IU/ml) were higher than without hCG, but, there are not significant difference among the treatment. On the other hand, expression of uPA after treatment of $IL-1{\beta}$ (0.1, 1, 10 and 100 ng/ml) were higher than without $IL-1{\beta}$, but, there are not significant difference. Expression of uPA after treatment of estrogen (0.2, 2, 20 and 200 ng/ml) were not difference, but PA activity was significantly decreased (p<0.05). Blastocyst was producing in PZM-3 medium containing FBS and endometrial cells were grown in PZM-3 medium. When embryos development with cultured endometrial cells, cleavage rates were not significant difference and blastocyst were not produced in co-culture with stromal cells and 3D culture system. 3D culture system had similar activity to in vivo tissue and these features are very useful for study of in vivo physiology. Nevertheless 3D culture system was not proper in embryo co-culture system. Therefore, we suggest that 3D culture system with embryo co-culture need continuous research.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.5
• /
• pp.133-138
• /
• 2022

Recently, as GPU performance has improved in HPC and artificial intelligence, its use is becoming more common, but GPU programming is still a big obstacle in terms of productivity. In particular, due to the difficulty of managing host memory and GPU memory separately, research is being actively conducted in terms of convenience and performance, and various CPU-GPU memory transfer programming methods are suggested. Meanwhile, recently many SoC (System on a Chip) products such as Apple M1 and NVIDIA Tegra that bundle CPU, GPU, and integrated memory into one large silicon package are emerging. In this study, data between CPU and GPU devices are used in such an integrated memory device and performance-related research is conducted during transmission. It shows different characteristics from the existing environment in which the host memory and GPU memory in the CPU are separated. Here, we want to compare performance by CPU-GPU data transmission method in NVIDIA SoC chips, which are integrated memory devices, and NVIDIA SMX-based V100 GPU devices. For the experimental workload for performance comparison, a two-dimensional matrix transposition example frequently used in HPC applications was used. We analyzed the following performance factors: the difference in GPU kernel performance according to the CPU-GPU memory transfer method for each GPU device, the transfer performance difference between page-locked memory and pageable memory, overall performance comparison, and performance comparison by workload size. Through this experiment, it was confirmed that the NVIDIA Xavier can maximize the benefits of integrated memory in the SoC chip by supporting I/O cache consistency.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.1
• /
• pp.1-7
• /
• 2014

Nanofluids, suspending nano-particles of various materials, have a good heat transfer characteristics compared with pure base fluids. For the reason, nanofluids have been considered as one of the measure to improve energy efficiency, and studied to apply on a working fluid of a high performance heat exchanger. This study tested thermal conductivities of nanofluids applying diamond nano-powder on DI water, ethylene glycol, and ethyl alcohol. Nanofluids are fabricated by matrix synthetic method, and the volume percent of diamond nano-powder contained in the base fluid are 0.1, 0.3, 0.5, and 1vol%. As a result, thermal conductivities are enhanced with applying diamond nano-power. Especially, the conductivity is highly increased up to 23% at 1vol% nanofluid applying diamond nano-powder on DI water.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.5 s.37
• /
• pp.313-322
• /
• 2005

In this paper, we implement and verify performance monitor for parallel signal processing system, using DSP Starter Kit(DSK) of which the basic Processor is TMS302C6711 chip. The key ideas of this performance monitor is, using Real Time Data Exchange(RTDX) for the Purpose of real-time data transfer and function of DSP/BIOS, the ability to measure the Performance measure like DSP workload, memory usage, and bridge traffic. In the simulation, FFT, 2D FFT, Matrix Multiplication, and Fir Filter, which are widely used DSP algorithms, have been employed. Using performance monitor and Code Composer Studio from Texas Instrument(Tl) , the result has been recorded according to different frequencies, data sizes, and buffer sizes for a single wave file. The accuracy of our performance monitor has been verified by comparing those recorded results.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.49 no.5
• /
• pp.226-232
• /
• 2000

This paper presents application results of the augmented matrix eigen-sensitivity theories to TCSC siting problem for damping the inter-area low frequency oscillation in the large KEPCO system. First and second-order eigen-sensitivities of the inter-area low frequency oscillation in the large KEPCO system. First and second-order eigen-sensitivities of the inter-area mode are computed fro changes in susceptance of the transmission lines. The lines having high sensitivity are chosen as the initial candidates for installing TCSC. Then for each of the chosen candidates, Bodeplot of the transfer function with line susceptance as the input and the bus voltage at one side of the line as the output is computed. Using the Bode plots, the lines having any zeros near the inter-area mode are screened out since design of TCSC controller is very difficult in such a case. The $H_{\infty}$ TCSC controller installed at any finally chosen candidate is found to be effective in damping the inter-area oscillation, and the proposed TCSC siting algorithm is proved to be valid. Design of $H_{\infty}$ controller is described in Part IIof this paper.

• Structural Engineering and Mechanics
• /
• v.27 no.6
• /
• pp.713-739
• /
• 2007

Nowadays computers can perform symbolic computations in addition to mere number crunching operations for which they were originally designed. Symbolic computation opens up exciting possibilities in Structural Mechanics and engineering. Classical areas have been increasingly neglected due to the advent of computers as well as general purpose finite element software. But now, classical analysis has reemerged as an attractive computer option due to the capabilities of symbolic computation. The repetitive cycles of simultaneous - equation sets required by the finite element technique can be eliminated by solving a single set in symbolic form, thus generating a truly closed-form solution. This consequently saves in data preparation, storage and execution time. The power of Symbolic computation is demonstrated by six examples by applying symbolic computation 1) to solve coupled shear wall 2) to generate beam element matrices 3) to find the natural frequency of a shear frame using transfer matrix method 4) to find the stresses of a plate subjected to in-plane loading using Levy's approach 5) to draw the influence surface for deflection of an isotropic plate simply supported on all sides 6) to get dynamic equilibrium equations from Lagrange equation. This paper also presents yet another computationally efficient and accurate numerical method which is based on the concept of derivative of a function expressed as a weighted linear sum of the function values at all the mesh points. Again this method is applied to solve the problems of 1) coupled shear wall 2) lateral buckling of thin-walled beams due to moment gradient 3) buckling of a column and 4) static and buckling analysis of circular plates of uniform or non-uniform thickness. The numerical results obtained are compared with those available in existing literature in order to verify their accuracy.

• Journal of Korean society of Dental Hygiene
• /
• v.13 no.1
• /
• pp.1-12
• /
• 2013

Objectives : In order to make a proposal of a Korean standard dental hygiene curriculum, the job description of the National Health Personnel Licensing Examination Board was analyzed to prepare a job analysis matrix of dental hygienist to select required core competency. Methods : Data were analyzed to test the job validity of dental hygienist and categorize the duties of dental hygienist. A proposal of a standard dental hygiene curriculum was mapped out by making a comparative analysis of the courses necessary for American authorization of dental hygiene curriculum, existing proposals of Korean standard dental hygiene curriculum and the courses of the departments of dental hygiene offered by domestic three-year colleges and four-year universities. Results : Basic medicine courses were reinforced or newly offered to provide an opportunity for students to transfer to a domestic four-year university or to a foreign university. In the field of clinical dental hygiene and practice, preventive dentistry, prophylaxis and practice were integrated, and the names of the related courses were unified to give a chance for students to engage in comprehensive dental hygiene practice. There were different courses for dental clinical science at present. In this proposal, students should earn 125 credits in total. Conclusions : Standard dental hygiene curriculum proposal was required by three-year and four-year colleges across the nation. To make it happen, the original names of dental hygiene courses should be used, and the dental hygiene certification and evaluation institute that is under the umbrella of the Korean Dental Hygienists Association should lay out the standard of the KSDHEP to facilitate the utilization of the standard dental hygiene curriculum proposal.

• Reproductive and Developmental Biology
• /
• v.34 no.2
• /
• pp.95-101
• /
• 2010

Decorin (DCN) is a member of small leucine-rich proteoglycans which are ubiquitous components of the extracellular matrix. It regulates many physiological processes, such as matrix formation, collagen fibrillogenesis, angiogenesis, cancer growth, and cardiovascular diseases. It has been shown that DCN is expressed in the uterus during pregnancy and modulates implantation and decidualization for the establishment and maintenance of pregnancy in mice and humans. Expression of DCN in the uterine endometrium during pregnancy has not been investigated in pigs. Thus, this study investigated expression of DCN in the uterine endometrium during the estrous cycle and pregnancy in pigs. Uterine endometrial tissues were from day (D) 12 and 15 of the estrous cycle and D12, D15, D30, D60, D90, and D114 of pregnancy. Northern blot and real-time RT-PCR analyses showed that expression of DCN mRNA was detected throughout the estrous cycle and pregnancy with the highest levels during mid pregnancy. In situ hybridization analysis showed that DCN mRNA was localized to both luminal and glandular epithelia during the estrous cycle and pregnancy and also to chorionic membrane during mid pregnancy in pigs. To determine whether endometrial expression of DCN was affected by the somatic cell nuclear transfer (SCNT) procedure, DCN mRNA levels in the uterine endometrium from gilts with SCNT embryos on D30 of pregnancy were compared with those from gilts with normal embryos using real-time RT-PCR analysis. The result showed that DCN mRNA levels in the uterine endometrium were not significantly different between gilts with normal embryos and SCNT embryos. These results suggest that DCN may play an important role for endometrial tissue remodeling during mid pregnancy, and DCN expression is not affected by the SCNT procedure at the early stage of pregnancy in pigs.

• Journal of Hydrogen and New Energy
• /
• v.22 no.6
• /
• pp.859-867
• /
• 2011

The cold start problem is one of major obstacles to overcome for the commercialization of fuel cell vehicles. However, the cold start characteristics of fuel cell systems are very complicated since various phenomena, i.e. ice-blocking, electro-chemical reactions, heat transfer, and defrosting of BOP components, are involved in them. This paper presents a framework to approach the problem at a full stack scale using Axiomatic Design (AD). It was characterized in terms of Functional Requirements (FRs) and Design Parameters (DPs) while their relations were established in a design matrix. Considering the design matrix, the endplates should have low thermal conductivity and capacity without increase in weight or decrease in structural stiffness. Consequently, composite sandwich endplates were proposed and examined both through finite element analyses and experiments simulating cold start conditions. From the examinations, it was found that the composite sandwich endplates significantly contributed to improving the cold start characteristics of PEMFC.