• International Journal of Aeronautical and Space Sciences
• /
• v.8 no.1
• /
• pp.1-9
• /
• 2007

As a first step toward a complete CFD-CSD coupling for helicopter rotor load analysis, the present study attempts to loosely couple a CFD code with a source-double panel method. The far-field wake effects were calculated by a time-marching free vortex wake method and were implemented into the CFD module via field velocity approach. Unlike the lifting line method, the air loads correction process is not trivial for the source-doublet panel method. The air loads correction process between the source-doublet method and CFD is newly suggested in this work and the computation results are validated against available data for well-known hovering flight conditions.

• Journal of the Microelectronics and Packaging Society
• /
• v.18 no.1
• /
• pp.7-13
• /
• 2011

According to increasing of data transfer rate, printed circuit board (PCB) is required improvement of transmission speed. Optical PCB and its packaging technology can be one of the solutions that overcome the limitations of conventional electrical PCB. The data transmission capacity will be increased 10 Tbps at 2015. To this end, studies on various OPCB technologies are being conducted. For cost-effective and high- performance OPCB, studies of optical coupling by polymer replication process are conducted. In this work, optical waveguide and optical fiber array block were sequentially fabricated by polymer pattern replication method. Using this method we successfully demonstrate low loss optical fiber coupling between optical waveguide and optical fiber arrays. And researches on flip chip bonding process and using electro-optic connectors for packaging are conducted.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.4
• /
• pp.76-81
• /
• 2008

A cryogenic butterfly valve is used to transfer the liquefied natural gas (LNG) which temperature is $-162^{\circ}C$. This valve is core part in the piping system using LNG. This paper performed coupling analysis using FEM to evaluate safety of cryogenic butterfly valve. Flow analysis is calculated numerically the CAE and CFD methods are useful to predict the thermal matter and the inner flow field of the valve. Thermal analysis and structural analysis used ANSYS Workbench.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.1
• /
• pp.107-109
• /
• 2008

Medicinal fungi, Phellinus linteus and Inonotus xeranticus, produce a cluster of yellow pigment in their fermentation broth that acts as an important element of biological activity. The pigment is composed of diverse polyphenols with a styrylpyrone moiety, mainly hispidin and its dimers, 3,14'-bihispidinyl, hypholomine B, and 1,1-distyrylpyrylethan. Although dimeric hispidins were proposed to be biosynthesized from two molecules of monomer via oxidative coupling by ligninolytic enzymes, laccase and peroxidase, the details of this process remain unknown. In this preliminary study, we attempted to achieve enzymatic synthesis of the hispidin dimer from hispidin by using commercially available horseradish peroxidase (HRP). Consequently, a hispidin dimer, 3,14'-bihispidinyl, was synthesized, whereas the other dimers, hypholomine B and 1,1-distyrylpyrylethan, were not produced. This result suggested that the oxidative coupling at the C-3 and C-14' positions of hispidins was dominant in the process of dimerization by HRP, and indicated that additional catalysts or substrates would be needed to synthesize other hispidin dimers present in the fungal metabolite.

• Korean Journal of Optics and Photonics
• /
• v.15 no.4
• /
• pp.293-298
• /
• 2004

We investigate the effect of the wing width and thickness of a Double-Sided Deep-Ridge(DSDR) vertical directional coupler on the coupling length dependent on the polarization, We have found that the DSDR vertical directional coupler without a wing does not have polarization independent coupling lengths. The variation of the coupling length of TE and TM modes and the difference between the coupling lengths of the two modes are negligible as the wing width increases beyond the specific wing width for the same wing thickness. Thus, we can see that a DSDR vertical directional coupler has a wing width larger than the minimum wing width to obtain the polarization independent coupling length. The minimum wing width increases as the wing thickness increases for the same core thickness and as the core thickness decreases for the same wing width. Also, we have found that the minimum wing thickness is determined by the core thickness and the minimum wing thickness decreases as the core thickness increases.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.47-54
• /
• 2020

Integration of active and passive waveguides is an essential component of the photonic integrated circuit and its elements. Butt joint is one of the important technologies to accomplish it with significant advantages. However, it suffers from high optical loss at the butt joint junction and need of accurate process control to align both waveguides. In this study, we used beam propagation method to simulate an integrated device composed of a laser diode and spot size converter (SSC). Two SSCs with different mode properties were combined with laser waveguide and optical coupling efficiency was simulated. The SSC with larger near field mode showed lower coupling efficiency, however its far field pattern was narrower and more symmetric. Tapered passive waveguide was utilized for enhancing the coupling efficiency and tolerance of waveguide offset at the butt joint without degrading the far field pattern. With this technique, high optical coupling efficiency of 89.6% with narrow far field divergence angle of 16°×16° was obtained.

• Wind and Structures
• /
• v.34 no.5
• /
• pp.437-450
• /
• 2022

Vortex-induced vibration (VIV) is a significant concern when designing slender structures with square cross sections. VIV strongly depends on structural dynamics and flow states, which depend on the conditions of the approaching flow and shape of a structure. Therefore, the effects of the angle of attack on the coupling effects of VIV for a square cylinder are expected to be significant in practice. In this study, the aerodynamic forces for a fixed and elastically mounted square cylinder were measured using wind pressure tests. Aerodynamic forces on the stationary cylinder are firstly discussed by comparisons of variation of statistical aerodynamic force and wind pressure coefficient with wind angle of attack. The coupling effect between the aerodynamic forces and the motion of the oscillating square cylinder by VIV is subsequently investigated in detail at typical wind angels of attack with occurrence of three typical flow regimes, i.e., leading-edge separation, separation bubble (reattachment), and attached flow. The coupling effect are illustrated by discussing the onset of VIV, characteristics of aerodynamic forces during VIV, and interaction between motion and aerodynamic forces. The results demonstrate that flow states can be classified based on final separation points or the occurrence of reattachment. These states significantly influence coupling effects of the oscillating cylinder. Vibration enhances vortex shedding, which creates strong fluctuations in aerodynamic forces. However, differences in the lock-in range, aerodynamic force, and interaction process for angles of attack smaller and larger than the critical angle of attack revealed noteworthy characteristics in the VIV of a square cylinder.

• Journal of Sport and Applied Science
• /
• v.7 no.2
• /
• pp.39-51
• /
• 2023

Purpose: The purpose of this study was to investigate differences in the control process to satisfy spatial and temporal constraints imposed upon the anticipation timing response by analyzing the effect of spatio-temporal accuracy demands on eye movements, response accuracy, and the coupling of eye and hand movements. Research design, data, and methodology: 12 right-handed male subjects participated in the experiment and performed anticipation timing responses toward a stimulus moving at three velocities (0.53m/s, 0.66m/s, 0.88m/s) in two task constraint conditions (temporal constraint, spatial constraint). During the response, response accuracy and eye movement patterns were measured from which timing and radial errors, the latency of saccade, fixation duration of the point of gaze (POG), distance between the POG and stimulus, and spatio-temporal coupling of the POG and hand were calculated. Results: The timing and radial errors increased with increasing stimulus velocity, and the spatio-temporal constraints led to larger timing errors than the temporal constraints. The latency of saccade and the temporal coupling of eye and hand decreased with increasing stimulus velocity and were shorter and longer respectively in the spatio-temporal constraint condition than in the temporal constraint condition. The fixation duration of the POG also decreased with increasing stimulus velocity, but no difference was shown between task constraint conditions. The distance between the POG and stimulus increased with increasing stimulus velocity and was longer in the temporal constraint condition compared to the spatio-temporal constraint condition. The spatial coupling of eye and hand was larger with the velocity 0.88m/s than those in other velocity conditions. Conclusions: These results suggest that differences in eye movement patterns and spatio-temporal couplings of stimulus, eye and hand by task constraints are closely related with the accuracy of anticipation timing responses, and the spatial constraints imposed may decrease the temporal accuracy of response by increasing the complexity of perception-action coupling.

• Journal of KIISE:Software and Applications
• /
• v.27 no.6
• /
• pp.595-606
• /
• 2000

Software metrics evaluate the development process, measure the software development effort, and control the software quality effectively. Moreover in a current status to emphasize reusability, it is necessary to study of cohesion and coupling that plays an important role in evaluating reusability. Object oriented methodology to use the concept like encapsulation, inheritance, and polymorphism demands metrics that are different from existing procedural methodology, so a study for object oriented metrics is in progress at the present time. In this paper, we propose cohesion and coupling metrics for object oriented program, evaluate the proposed metrics by using the complexity properties proposed by Weyuker and Briand, and extract cohesion and coupling from C++ code.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.1
• /
• pp.18-24
• /
• 2010

Efforts to obtain more efficient coupling of light from a laser diode to a single mode fiber have continued for various applications such as links for optical fiber communication systems. In TO-can package, configuration of optimized aspherical lens is bi-aspheric and its diameter is 2.4mm. We designed and fabricated aspherical coupling lens by means of glass molding technique under consideration of glass shrinkage. By controlling the aspherical profile error and surface roughness which were below 90nm and 10nm, respectively, we obtained the low coupling loss, 5.40dB, which was able to use for coupling a single mode fiber to laser diode.