• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.359-364
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• 2003

We propose a novel vertical directional coupler with polarization independent very short coupling lengths using the double-sided deep-ridge waveguide structure which could be implemented using double-sided process to polarization insensitive deep-ridge waveguide structures and investigate the effect of various structure parameters on the coupling length. Variation of coupling length for the variation of the waveguide width is smaller than that for the variation of the core thickness. Coupling length decreases as the inner cladding layer thickness and the core thickness decrease. The waveguide width with the polarization independent coupling length decreases as the inner cladding layer thickness decreases for the same core thickness and the core thickness decreases for the same inner cladding layer thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.32-35
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• 2002

The work focuses on the development of a Cu lead-frame with a single-sided adhesive tape for cost reduction and reliability improvement of LOC (lead on chip) package products, which are widely used for the plastic-encapsulation of memory chips. Most of memory chips are assembled by the LOC packaging process where the top surface of the chip is directly attached to the area of the lead-frame with a double-sided adhesive tape. However, since the lower adhesive layer of the double-sided adhesive tape reveals the disparity in the coefficient of thermal expansion from the silicon chip by more than 20 times, it often causes thermal displacement-induced damage of the IC pattern on the active chip surface during the reliability test. So, in order to solve these problems, in the resent work, the double-sided adhesive tape is replaced by a single-sided adhesive tape. The single-sided adhesive tape does net include the lower adhesive layer but instead, uses adhesive materials, which are filled in clear holes of the base film, just for the attachment of the lead-frame to the top surface of the memory chip. Since thermal expansion of the adhesive materials can be accommodated by the base film, memory product packaged using the lead-flame with the single-sided adhesive tape is shown to have much improved reliability. Author allied this invention to the Korea Patent Office for a patent (4-2000-00097-9).

• Steel and Composite Structures
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• v.29 no.1
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• pp.1-22
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• 2018

Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. Welded plate beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is at present limited information concerning their detailed structural behaviour under bending and shear loadings. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections in full scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and weld arrangements conformed with successful commercial practice. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the connections. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. In general, the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided welded plate connection test results are presented in this paper. The behaviour of single sided welded plate connection test results is the subject of another paper.

• Steel and Composite Structures
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• v.29 no.5
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• pp.603-622
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• 2018

Precast concrete structures are erected from individual prefabricated components, which are assembled on-site using different types of connections. In the present design of these structures, beam-to-column connections are assumed pin jointed. Bolted billet beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is currently limited information concerning their detailed structural behaviour under vertical loadings. The experimental work has involved the determination of moment-relative rotation relationships for semi-rigid precast concrete connections in full-scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and bolt arrangements conformed to successful commercial practice. Proprietary hollow core floor slabs were tied to the beams by 2T25 tensile reinforcing bars, which also provide the in-plane continuity across the connections. The contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. The flexural strength of the connections in the double-sided tests was at least 0.93 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.94 to 1.94 times the flexural stiffness of the attached beam. In general, the double-sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided bolted billet connection test results are presented in this paper. The behaviour of single sided bolted billet connection test results is the subject of another paper.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.1
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• pp.49-55
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• 1996

In this paper, the characteristics of a double-sided linear pulse motor (DLPM) with permanent magnet are analysed using the method which combined the coenergy method and the equivalent magnetic circuit method. In the process of computation, the magnetic material nonlinealities of the permanent magnet, the primary and the secondary core are interpolated by the cubic spline method. Then, the equivalent magnetic circuit modelled by the permeance method including airgap reluctance, which is a function of displacement, is obtained. The static thrust which is the derivative of coenergy is computed by Newton Raphson method at each dispacement. And, in order to investigate the characteristics of the DLPM, the thrust shows as a function of displacement, input current and air gap. The simulation resuls are compared with experimental ones obtained from the DLPM with 2 phase and 4 poles.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.12-16
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• 2004

We show that the extinction ratio is improved using slight asymmetry in two core refractive indices of polarization independent very short vertical directional couplers with the double-sided deep-ridge (DSDR) waveguide structure. The optimum asymmetry with the maximum extinction ratio and the tolerance of the refractive index of core with the extinction ratio larger 1ha]1 30 ㏈ increase as the thickness of inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. Also, the device length and the tolerance of the device length with the extinction ratio larger than 30 ㏈ decrease as the thickness of the inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. We show that polarization independent vertical directional couplers with the DSDR waveguide structure with the device length less than 100 ${\mu}{\textrm}{m}$ and the extinction ratio larger than 30 ㏈ could be implemented.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.293-298
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• 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 Sensor Science and Technology
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• v.31 no.1
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• pp.36-40
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• 2022

High-power devices, such as LEDs and radars, inevitably generate a large amount of heat, which is the main cause of shortening lifespan, deterioration in performance, and failure of electronic devices. The embedded IC process can be a solution; however, when applied to large-area substrates (larger than 8 in), there is a limit owing to the difficulty in the process after wafer thinning. In this study, an 8-in wafer-level high-power electronic package based on the embedded IC process was implemented with temporary bonding and debonding technology using double-sided thermal release tape. Good heat-dissipation characteristics were demonstrated both theoretically and experimentally. These findings will advance the commercialization of high-power electronic packaging.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.209-213
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• 2008

In this work, we have proposed a method for calculating the residual stress developed during the PCB thermo-compression bonding precess. Residual stress is the most important factor that causes PCB warpage in accordance with the pattern design. In this work, a single-layed double-sided PCB, which is comprised of the dielectric (FR-4) substrate in the middle and copper cladding on the both top and bottom sides, is considered. A reference temperature, where all stress is free, is calculated by comparing the calculated and measured warapge of a PCB of which copper cladding of the top side is removed. Then, the reesidual stress values is calculated for the double-sided PCB.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.111-118
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• 2018

In order to develop a local stiffness-variant stretchable substrate with the soft PDMS/hard PDMS/FPCB configuration consisting of two stiffness-different polydimethylsiloxane (PDMS) parts and flexible printed circuit board, a FPCB was bonded to PDMS using the acrylic-silicone double-sided tape and the interfacial adhesion of the PDMS/FPCB was evaluated. The pull strength of the FPCB, which was bonded to the fully cured PDMS using the silicone adhesive of the double-sided tape, was 259 kPa and the delamination during the pull test occurred at the interface between the PDMS and the silicone adhesive. On the contrary, the bonding process, for which the FPCB was bonded using the silicone adhesive to the PDMS partially cured for 15~20 minutes at $60^{\circ}C$ and then the PDMS was fully cured for 12 hours at $60^{\circ}C$, exhibited the remarkably enhanced pull strength of 1,007~1,094 kPa. With the above mentioned bonding process, the delamination during the pull test was observed at the interface between the FPCB and the acrylic adhesive of the acrylic-silicone double sided tape.