• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.137-138
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• 2013

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.502-507
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• 2004

The forward planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 300 KHz, was designed and manufactured by using the planar core with large effective area and the flat copper leadframes for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a forward converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 15 and 2 respectively The self inductance of 1st winding was 1.592 mH, very low leakage inductance of 2.7 $\mu$H, and the coupling factor of 0.928 were obtained at switching frequency of 300 KHz. The high efficiency of 88.62 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.19-22
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• 2004

The resonant planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 500 kHz, was designed and manufactured by using the planar core with large effective area and the flat copper lead frames for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a resonant converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 12 and 2 respectively. The self inductance of 1st winding was 33.2 ${\mu}H$, very low leakage inductance of 1.27 ${\mu}H$, and the coupling factor of 0.98 were obtained at switching frequency of 300 kHz. The high efficiency of 88.21 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• 한국기계가공학회지
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• 제19권7호
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• pp.35-40
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• 2020

This work is concerned with various planar deformations of an isotropic sandwich beam, which generally consists of three layers: two stiff skin layers and one soft core layer. When one layer of the sandwich beam is modeled as a beam, the variational-asymptotic method is rigorously used to construct a zeroth-order beam model, which is similar to a generalized Timoshenko beam model capable of capturing the transverse shear deformations but still carries out the zeroth-order approximation. To analyze the planar sandwich beam, the sum of the energies of the two skin layers and one core layer is then formulated with different material and geometric properties and represented by a universal beam model in terms of the core-layer kinematics through interface displacement and stress continuity conditions. As a preliminary validation, two extreme examples are presented to demonstrate the capability and accuracy of this present approach.

• International Journal of Automotive Technology
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• 제6권3호
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• pp.259-268
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• 2005

In order to analyze the sheet drawability, the measurement of the plastic strain ratio was carried out for the 5182 aluminum alloy sheets in which were cold rolled without lubrication and subsequent recrystallization annealing. The average plastic strain ratio of the 5182 aluminum sheets was 1.50. It was considered that the higher plastic strain ratio was resulted from the ND//<111> component evolved during rolling and maintained during annealing. The AA5182/polypropylene/AA5182 (AA/PP/AA) sandwich sheets of the 5182 aluminum alloy skin sheet and the polypropylene core sheet with high formability have been developed for application for automotive body panels in future light weight vehicles with significant weight reduction. The AA/PP/AA sandwich sheets were fabricated by the adhesion of the core sheet and the upper and lower skin sheets. The AA/PP/AA sandwich sheet had high plastic strain ratio (1.58), however, the planar anisotropy of the sandwich sheet was little changed after fabrication. The optimum combination of directionality of the upper and lower skin sheets having high plastic strain ratio and low planar anisotropy was calculated theoretically and an advanced process for producing the sandwich sheets with high plastic strain ratio was proposed. The developed sandwich sheets have a high average plastic strain ratio of 1.55 and a low planar anisotropy of 0.17, which was improved more by 3.2 times than that of 5182 aluminum single sheet.

• Journal of Information Display
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• 제5권1호
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• pp.34-40
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• 2004

Time resolved infrared IR absorption spectroscopy is carried out to investigate the dynamics of electric field induced reorientation of the biphenyl molecular core and alkyl tail sub-fragments of the nematic liquid crystal 5CB (4-pentyl-4-cyano-biphenyl). The planar to homeotropic transition for high pre-tilt planar aligned cells, is studied for switching times ranging from 200 ${\mu}sec$ down to 80 ${\mu}sec$, the latter a factor of 1000 times faster than any previous nematic IR study. The reorientation rates of the core and tail are found to be the same to within experimental error and scale inversely with applied field squared, as expected for the balance of field and viscous torques. Thus any molecular conformation change during switching must relax on a shorter time scale. A simple model shows that no substantial differences exist between the reorientational dynamics of the tails and cores on the time scales longer than on the order of 10 ${\mu}s$.

• 한국전기전자재료학회논문지
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• 제11권9호
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• pp.739-745
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• 1998

The objective of this paper is to provide experimental data of Er(rare- earth)doped $SiO_2$thin film made by sputtering methods. The deposition rate of silica glass by sputtering method was 55$\AA$/min. In EDD measurements, the average Er concentration in the deposited film was 0.77(wt%). After annealing at $900^{\circ}C$, the Cl concentration decreased from 3.79(wt%) to 1.52(wt%). The refractive indices of the core $n_1$, cladding $n_2$ were 1.458, 1.558 respectively at 632.8 nm. The refractive index difference between core and cladding, $\Delta$n was 0.1. The refractive index profile of core and cladding interface shows step profile. In the study, $SiO_2$ glass films of Si wafer were successfully doped with active erbium. Therefore, this experimental data will be applicable for fabrications of Er doped planar integrated optical device.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.157-159
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• 2020

This paper presents an optimal planar transformer design of a 3-kW Low voltage DC-DC Converter (LDC) with 3.68 kW/L power density for electric vehicle (xEV) application. The transformer is optimized based on the trade-off between footprint and loss using the proposed figure-of-merit (FOM) based optimization. In order to achieve ZVS under entire load range, an external leakage inductance is added and implemented using the proposed magnetic integration technique. A comparison between non-integrated and integrated magnetic core using finite element analysis (FEA) is presented. The result shows that the integrated core can reduce the core loss up to 35 % and core boxed volume up to 15 % compared to the non-integrated core. Experimental results are also provided to validate the proposed magnetic integration technique.

• 전력전자학회논문지
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• 제17권2호
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• pp.121-128
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• 2012

In this paper, a new planar transformer with a novel core configuration that can regulate the leakage inductance is proposed and described in detail. In order to design the slim size power system for flat panel TV, Two planar transformers applied to LLC resonant converter are connected in series at primary and in parallel by the center-tap winding at secondary. In this paper, a 300W low profile LLC resonant converter was built and tested to verify the proposed planar transformer.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1996년도 춘계연구발표회 논문개요집
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• pp.64-65
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• 1996