• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.317-319
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• 1993

The function estimation characteristics of neural networks can be used for sensor signal validation of a system. In case of applying the neural networks to signal validation, it is a important problem that the redundant sensor signals used as a input signal of neural networks should be validated. In this paper, we simplify the conventional parity space method in order to input the validated signal to the neural networks and also propose the sensor signal validation method, which estimates the reliable sensor output combining neural networks with the simplified parity space method. The acceptability of the proposed signal validation method is demonstrated by using the simulation data in safety injection accident of nuclear power plants.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.49-56
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• 2004

A new readout circuit(ROIC) for linear HgCdTe 64${\times}$2 two-color Infrared (IR) detector is described. This circuit is based on the buffered direct injection(BDI) technology with high injection efficiency. By using saturation current isolation circuit, the proposed ROIC removed the problems that LWIR(Long Wavelength InfraRed) signal distort when MWIR(Middle Wavelength InfraRed) signal saturates so that new ROIC has larger measurable temperature range about 120k than that of previous circuit and it is also tolerant for dead pixel in MWIR detector. The designed circuit was fabricated using 0.6um 2-poly 3-metal CMOS process. We measured that the designed circuit outputs MWIR signal and LWIR signal simultaneously and saturation current isolationcircuit also operates well. Next, measured noise was about 53uV at room temperature and it can be assumed that designed circuit can satisfy nearly 95% BLIP condition at 77K.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.295-296
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• 2008

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.78-84
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• 2005

In the chemical laser system with a radial expansion nozzle array, the laser beam generation is achieved by mixing F atom from supersonic nozzle and $D_{2}$ molecule from holes of round-bended supply line. Based on that the fuel injection angle with main stream has a great influence of performance on supersonic combustor, the effects of $D_{2}$ injection angles with the main F flow on mixing enhancement are numerically investigated. The results are discussed by comparison with three cases of $D_{2}$ injection angles; $10^{o}$, $20^{o}$ and $40^{o}$ with the main flow direction. Major results reveal that as the $D_{2}$ injection angle increases, the maximum small signal gains and the static pressure in the laser cavity become higher. Consequently, the $D_{2}$ injection angle between $20^{o}$ and $40^{o}$ is recommended as an optimized geometric parameter in consideration of both of high gains and low cavity pressure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.217-225
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• 2009

Tone injection scheme has been known as one of peak to average power ratio (PAPR) reduction methods deployable to multi-carrier system like orthogonal frequency division multiplexing (OFDM). The basic idea in tone injection scheme is to enforce the constellation size larger so that each of original constellation points is mapped into the preassigned distinct locations. According to the tone injection scheme, it increases symbol power highly induced inherently by expanding constellation to get optimal PAPR reduction. In the other hand, to get optimal power increase, the PAPR would be reduced insufficiently with limited tone injection signal. To withstand these problems, this paper consider the reduction of the PAPR and power increase problem simultaneously, Toward this, the tone injection scheme accomplished by employing the weighted sum genetic algorithm which has been utilized to solve multi-objective optimization problem (MOOP). The simulation results verifies that the proposed scheme can control the effective PAPR performance and alleviation of power increase flexibly by the weight value at the expense of relatively low complexity.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.42-51
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• 2012

In this paper, injection-locking characteristics versus active layer structures in Fabry-Perot laser diodes (FP-LD) are compared. TE and TM gain spectra and peak gains versus carrier density in polarized and unpolarized multiple quantum well structures and in an unpolarized bulk structure are calculated. The calculated gain parameters are applied to a time-domain large-signal model to simulate the injection-locking characteristics. The results show that RIN in unpolarized FD-LDs is about 3 dB lower than that in a polarized FP-LD and that the eye characteristics of the unpolarized FP-LD are much better than those of the polarized FP-LD.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2373-2385
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• 1995

The goals of this study are to apply exciplex method to the visualization of the fuel spray of a diesel engine and to investigate the liquid phase of fuel spray that injected at the various tips of a fuel injector. This study provides the informations for the improvement of the diesel injection system and the structures of diesel spry with the boiling of fuel droplets in combustion chamber by the exciplex method. Hexame was used as fuel for approximation to injection condition of the engine. And naphthalene and TMDP were added to the fuel for the visualization by exciplex method. Experimental injectors were 4hole, 8hole, and 1hole impinging injectors. In the injection condition of actual engine the exciplex was sufficient to catch the liquid phase signal. The spray penetration of impinging injector was small than that of actual 4 and 8hole injector but atomization was better. The upper bound of impinging injector was determined by the geometry of a cylinder head and the lower bound was determined by spray angle. On impinging injector the atomization was better at the edge of disk than at center of disk and also the mixing with environmental gas was better.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.73-81
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• 2014

In this paper, multiple gate locations and process conditions under concern are automatically optimized by considering robustness to minimize the injection pressure required to mold an automotive dashboard. Computer simulation-based experiments using orthogonal arrays(OA) and a design-range reduction algorithm are consolidated into an iterative search scheme, which is then used as a tool for the optimization process. The robustness of a design is evaluated using an OA-based simulation of process fluctuations due to noise as well as the signal-to-noise ratio. The optimal design solution for the automotive dashboard shows that the robustness of the injection pressure is significantly improved when compared to the initial design. As a result, both the die clamping force and the pressure distribution in the part cavity are also much improved in terms of their robustness.

• Design & Manufacturing
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• v.17 no.3
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• pp.34-40
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• 2023

In this study, real-time collection of mold vibration signals during injection molding processes was achieved through IoT devices installed on the mold surface. To analyze changes in the collected vibration signals, injection molding was performed under six different process conditions. Analysis of the mold vibration signals according to process conditions revealed distinct trends and patterns. Based on this result, cosine similarity was applied to compare pattern changes in the mold vibration signals. The similarity in time and acceleration vector space between the collected data was analyzed. The results showed that under identical conditions for all six process settings, the cosine similarity remained around 0.92±0.07. However, when different process conditions were applied, the cosine similarity decreased to the range of 0.47±0.07. Based on these results, a cosine similarity threshold of 0.60~0.70 was established. When applied to the analysis of mold vibration signals, it was possible to determine whether the molding process was stable or whether variations had occurred due to changes in process conditions. This establishes the potential use of cosine similarity based on mold vibration signals in future applications for real-time monitoring of molding process changes and anomaly detection.

• Design & Manufacturing
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• v.18 no.2
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• pp.41-50
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• 2024

In this study, experimental design methods were used to derive optimal process conditions for improving the thickness uniformity of a 0.40 mm, 3.5 inch light guide panel. Process mapping and expert group analysis were used to identify factors that influence the thickness of injection molded products. The key factors identified were mold temperature, mold temperature, injection speed, packing pressure, packing time, clamp force, and flash time. Considering the resin manufacturer's recommended process conditions and the process conditions for similar light guide plates, a three-level range was selected for the identified influencing factors. L27 orthogonal array process conditions were generated using the Taguchi method. Injection molding was performed using these L27 orthogonal array to mold the 3.5 inch light guide plates. Thickness measurements were then taken, and the results were analyzed using the signal-to-noise ratio to maximize the CpK value, leading to the determination of the optimal process conditions. The thickness uniformity of the product was analyzed by applying the derived optimum process conditions. The results showed a 97.5% improvement in the Cpk value of 3.22 compared to the process conditions used for similar light guide plates.