• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.93-99
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• 2016

The trimming process is required for satisfying the dimensions of a final product in the hot stamping process. In general, the mechanical trimming or laser trimming process is applied after hot stamping. However, these processes have several disadvantages such as short tool life and low productivity. Therefore, in this study, the optimal trimless blank shape for the hot stamping process of a sill side was designed to remove the trimming process after hot stamping. In order to design the trimless blank, numerical analysis was performed. Firstly, CFD analysis was carried out to predict the cooling temperature and holding time of the hot stamping process. Then, the optimal trimless blank shape was determined through FE analysis. The effectiveness of the designed trimless blank shape was verified through a hot stamping experiment at an actual industrial site.

• Korean Journal of Bronchoesophagology
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• v.3 no.1
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• pp.128-136
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• 1997

Laryngomalacia is the most common cause of stridor in infant. It is a relatively benign self-limiting condition, but in severe cases, it results in obstructive sleep apnea, cor pulmonale , gastroesophageal reflux, failre to thrive, pectus excavatum, respiratory failure and death. When the airway obstruction related to laryngomalacia becomes significant, surgical correction of the underlying laryngeal deformity is indicated. Numerous reports provide evidence to support the trimming supraglottic soft tissue by using either conventional instruments or the surgical laser for treatment of severe laryngomalacia. Recently, authors experienced a case of laryngomalacia with Trisomy 13 (Patau syndrome) which had three times respiratory arrest and was treated with laser aryepiglottoplasty. We report this case with review of the literatures.

• ETRI Journal
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• v.26 no.6
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• pp.589-596
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• 2004

Packaging technologies for a broadband and narrowband modulator with a traveling wave electro-absorption modulator (TWEAM) device were developed. In developing a broadband modulator, the effects of the device and packaging designs on the broadband performance were investigated. The optimized designs were obtained through a simulation with the result that we developed a broadband modulator with a 3 dB bandwidth of 38 GHz in the electrical-to-optical (E/O) response, an electrical return loss of less than -10 dB at up to 26 GHz, an rms jitter of 1.832 ps, and an extinction ratio of 5.38 dB in a 40 Gbps non-return to zero (NRZ) eye diagram. For analog application, the effect of the RF termination scheme on the fractional bandwidth was studied. The microstrip line with a double stub as a matching circuit and a laser trimming process were used to obtain an $S_{11}$ of -34.58 dB at 40 GHz and 2.9 GHz bandwidth of less than -15 dB.

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.221-222
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• 2007

The UV laser trimming can be useful to have an accurate performance specification of the passive waveguide devices. In order to measure the change of the refractive index of polymer overclad layer under the irradiation of uv light in a high precision Bragg grating is fabricated on the silica core of planar waveguide and the corresponding transmittance spectrum was analyzed. An effective refractive index change of $4.7x10^{-5}$ was obtained for a straight waveguide when its $60{\mu}m$-thick overclad was irradiated by UV laser pulses of its total fluence 24 $J/cm^2$.

• Design & Manufacturing
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• v.11 no.2
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• pp.37-41
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• 2017

With light vehicle weight gradually becoming ever more importance due to tightened exhaust gas regulations, hot-stamping processing using boron alloyed steel is being applied more and more by major automobile OEMs since process assures both moldability and a high strength of 1.5 GPa. Although laser trimming is generally applied to the post-processing of the hot-stamped process with high strength, there have been many studies of in-die hot trimming using shear dies during the quenching of material in order to shorten processing times. As such, this study investigated the effects of the Shear rate and Shear mechanism on shear processes during the quenching process of hot-stamping material. In case of pad variable, padding force is very weak compared with shear force, so it does not affect the shear surface. In case of shear rate, the higher the shear at high temperatures and the higher the friction effect. As a result the rollover and the fracture distribution decreased, and the burnish distribution increased. Therefore, it is considered that the shear quality is guaranteed when high shear rate is applied in high temperature shear process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1663-1668
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• 2011

Surface hardening treatment is required to improve the wear-resistance of press die because severe abrasion of die occurs during the drawing process in which the forming of the automotive body is completed and during the trimming process in which the unnecessary parts are cut. In this study, experiments on the laser surface treatment of press die are performed. Specimens are heat-treated separately at certain plate and edge position by using a diode laser to carry out suitable surface hardening treatment to reduce the wear during the drawing and the trimming processes, and the proper conditions for heat treatment are found. Spheroidal and flake graphite cast iron specimens are used, and the heat treatment characteristics of the two materials are compared. From the results of the study, it is confirmed that the heat treatment characteristics differed depending on the materials.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.358-364
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• 2002

In this paper, we used U.V.(wavelength, 355nm) laser for adjusting Pt thin films temperature sensor to $100{\Omega}$ at $0^{\circ}C$. Internationally, A-class tolerance of temperature sensor is $0.06{\Omega}$ at $0^{\circ}C$. This is under value of $0.15^{\circ}C$, actually, so high-fine trimming technology is essential to this process. The width of trimmed lines was about $10{\mu}m$ and the best trimming of Pt thin films of $1{\sim}1.5{\mu}m$ was carried out with power : 35mW, rep. rate frequency : 200Hz and bite size : $1.5{\mu}m$. And using photolithography process, 96 resistors were fabricated in $2"{\times}2"$ substrate as the proportion of $79{\sim}90{\Omega}$ and $91{\sim}102{\Omega}$ is 42.7% and 57.3%, respectively. As result of trimming resistors to the target value of $109.73{\Omega}$ at $25^{\circ}C$, 82.3% of resistors had the tolerance within ${\pm}0.30{\Omega}$ and the others(17.7%) were within ${\pm}0.06{\Omega}$ of A-class tolerance.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.128-134
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• 2006

Two-dimensional nano-patterns are fabricated using immersion holographic lithography. The photoresist layer is exposed to an interference pattern generated by two incident laser beams($\lambda$=441.6 nm, He-Cd laser) of which the pitch size is less than 200 nm. Good surface profiles of the 2 dimensional patterns are achieved by trimming the lithography process parameters, such as, exposure time, developing time and refractive index of medium liquid.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.31-36
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• 1997

Various methods of finite element modeling for welded part are examined and the stamping simulation of automotive body is presented by using the explicit finite element code PAM-STAMPTM. The process of stamping simulation is suggested step by step, and then the gravity, binder wrap, forming, trimming and springback of front door inner are analyzed. It shows good agreements with real product in the aspects of deformed shape and failure area. The door inner with laser-tailor welded blank is simulated, in which deformed shape, movement of welde line and formability are predicted.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.573-576
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• 2005

A compact linear and angular displacement measurement device was developed by combining a Michelson interferometer and an autocollimator to characterize the movement of a precision stage. A Michelson interferometer and an autocollimator are typical devices for measuring linear and angular displacement, respectively. By controlling the polarization of reflected beam from the target mirror of the interferometer, some part of light was retro-reflected to the light source and the reflected beam was used for angle measurement. The interferometer and the autocollimator use the same optic axis and the target mirror can be easily and precisely aligned orthogonal to the optic axis by monitoring the autocollimator s signal. The autocollimator was designed for angular resolution of 0.1 arcsec and dynamic range of 60 arcsec. The nonlinearity error of interferometer was minimized by trimming the gain and offset of the photodiode signals. Through the experiments, we evaluate the performance of measurement device and discuss its applications.