• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1546-1552
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• 2016

In addition, because it uses preheating to dissolve an alloy in general, it is hard to regulate the appropriate melting temperature of the alloy and brewing time and shows the defect of the supplementation thing due to the super-heating. Once the alloy is molten and then most of the casting by attaching a sight glass or non-contact temperature sensor is suitable casting temperature the operator pressing a button to generate a centrifugal force to inject the molten alloy into a crucible in the casting ring. These results, and most of the cast temperature is too high or too low to generate a lot of casting defects do not get into a uniform cast body. In this paper, we developed a dental casting machine for high frequency using a single temperature sensor which can measure the actual temperature of the alloy than the temperature of the external non-contact measurement using a temperature sensor.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1504-1512
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• 2007

The fpr gene, which encodes a ferredoxin-$NADP^+$ reductase, is known to participate in the reversible redox reactions between $NADP^+$/NADPH and electron carriers, such as ferredoxin or flavodoxin. The role of Fpr and its regulatory protein, FinR, in Pseudomonas putida KT2440 on the oxidative and osmotic stress responses has already been characterized [Lee at al. (2006). Biochem. Biophys. Res. Commun. 339, 1246-1254]. In the genome of P. putida KT2440, another Fpr homolog (FprB) has a 35.3% amino acid identity with Fpr. The fprB gene was cloned and expressed in Escherichia coli. The diaphorase activity assay was conducted using purified FprB to identify the function of FprB. In contrast to the fpr gene, the induction of fprB was not affected by oxidative stress agents, such as paraquat, menadione, $H_2O_2$, and t-butyl hydroperoxide. However, a higher level of fprB induction was observed under osmotic stress. Targeted disruption of fprB by homologous recombination resulted in a growth defect under high osmotic conditions. Recovery of oxidatively damaged aconitase activity was faster for the fprB mutant than for the fpr mutant, yet still slower than that for the wild type. Therefore, these data suggest that the catalytic function of FprB may have evolved to augment the function of Fpr in P. putida KT2440.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.354-361
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• 1999

The films annealed after physical deposition of titanium and chemical deposition of amorphous silicon by plasma were formed Si-rich titanium silicide with a good quality of crystallinity and had the various lattice structures due to orientation of lattices for epitaxy growth during annealing process. Band gap of the titanium silicide had 1.14~1.165 eV and the films annealed after chemical deposition of a-Si:H by plasma were influenced by a-Si and the dangling bond offered by desorption of hydrogen. Urbach tail ($E_0$) of the films annealed after physical deposition of Ti was nearly constant within a range of 0.045~0.05 eV, and the number of defect in films annealed after chemical deposition of a-Si:H by plasma was about 2~3 times more than that in annealed Ti/Si films.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.407-415
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• 2011

The stability condition and wideband characteristics of 3D ID-FDTD algorithm which has low dispersion error with isotropic dispersion are presented in this paper. 3D ID-FDTD method was proposed to improve the defect of the Yee FDTD such as the anisotropy and large dispersion error. The published paper calculated the stability condition of 3D ID-FDTD algorithm by using numerical method, however, it is thought that the examples were not sufficient to verify the stability condition. Thus, in this paper, various simulations are included in order to hold reliability under the conditions that the plane wave propagation is assumed with a single frequency and a wideband frequency. Also, the 3D ID-FDTD algorithm is compared to those that have the similar FDTD algorithm with ID-FDTD such as Forgy's method and non-standard FDTD method in a wideband. Finally, the radar cross section(RCS) for the large sphere with high dielectric constant is calculated.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.56-64
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• 2018

In recent years, imbalanced data is one of the most important and frequent issue for quality control in industrial field. As an example, defect rate has been drastically reduced thanks to highly developed technology and quality management, so that only few defective data can be obtained from production process. Therefore, quality classification should be performed under the condition that one class (defective dataset) is even smaller than the other class (good dataset). However, traditional multi-class classification methods are not appropriate to deal with such an imbalanced dataset, since they classify data from the difference between one class and the others that can hardly be found in imbalanced datasets. Thus, one-class classification that thoroughly learns patterns of target class is more suitable for imbalanced dataset since it only focuses on data in a target class. So far, several one-class classification methods such as one-class support vector machine, neural network and decision tree there have been suggested. One-class support vector machine and neural network can guarantee good classification rate, and decision tree can provide a set of rules that can be clearly interpreted. However, the classifiers obtained from the former two methods consist of complex mathematical functions and cannot be easily understood by users. In case of decision tree, the criterion for rule generation is ambiguous. Therefore, as an alternative, a new one-class classifier using hyper-rectangles was proposed, which performs precise classification compared to other methods and generates rules clearly understood by users as well. In this paper, we suggest an approach for improving the limitations of those previous one-class classification algorithms. Specifically, the suggested approach produces more improved one-class classifier using hyper-rectangles generated by using Gaussian function. The performance of the suggested algorithm is verified by a numerical experiment, which uses several datasets in UCI machine learning repository.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.190-200
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• 2014

The video-based system of the broadcasters and the video-related institutions have shifted from analogical to digital in worldwide. This migration process can generate a defect, digital dropout, in the quality of the contents. Moreover, there are limited researches focused on these kind of defects and those related have limitations. For that reason, we are proposing a new method for feature extraction emphasizing in the peculiar block pattern of digital dropout based on discrete cosine transform (DCT). For classification of error block, we utilize support vector machine (SVM) which can manage feature vectors efficiently. Further, the proposed method overcome the limitation of the previous one using continuity of frame by frame. It is using only the information of a single frame and works better even in the presence of fast moving objects, without the necessity of specific model or parameter estimation. Therefore, this approach is capable of detecting digital dropout only with minimal complexity.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1770-1772
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• 2003

본 연구는 국내에서 최초로 제안되고 적용가능성이 입증되어 설계, 제작된 Probe-type Pockets sensor(HY-Pockets Sensor)를 GIS등의 고전압 장비들에 응용한 레이저 부분방전 진단 시스템 개발을 목표로 하고 있다. 이러한 목적으로, 170kV 급 실 규모 GIS내부의 전류 도체에 다양한 곡률 반경의 침 전극을 부착시켜 부분 방전에 기인된 불평등 전계를 형성시켜 개발된 센서의 실규모 적용 가능성을 고찰하였다. 본 레이저 계측 시스템은 He-Ne laser, single multi-mode optical fiber, $2{\times}2$ 50/50 laser to single mode fiber coupler, probe-type Pockets sensor, photo detector 등으로 구성하여 레이저의 진행을 유도하고, 신호의 특성을 분석하였다. probe-type Pockets sensor로부터 의 출력 신호는 photo detector를 통해 전기적 신호로 변환되어 digital oscilloscope에 의해 측정되고, 또한 PC를 통해 데이터의 저장과 통계적, 분석적 처리 과정을 수행하게 된다. 본 연구의 결과로서 부분방전원에서 생성된 방전 신호에 대한 거리에 따른 센서 감도 결정, 그에 대한 센서 감도의 보정 향상, 전계의 세기의 변화에 따른 센서의 선형성 등이 도출되었고, 이러한 실험결과를 통해 실 GIS(170kv급) 내부에서 발생하는 부분방전의 검출에 본 레이저 부분방전 진단 시스템의 적용 가능성이 제시 되었다.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.335-341
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• 2012

Recently, the demand for the miniaturization of printed circuit boards has been increasing, as electronic devices have been sharply downsized. Conventional multi-layered PCBs are limited in terms their use with higher packaging densities. Therefore, a build-up process has been adopted as a new multi-layered PCB manufacturing process. In this process, via-holes are used to connect each conductive layer. After the connection of the interlayers created by electro copper plating, the via-holes are filled with a conductive paste. In this study, a desmear treatment, electroless plating and electroplating were carried out to investigate the optimum processing conditions for Cu via filling on a PCB. The desmear treatment involved swelling, etching, reduction, and an acid dip. A seed layer was formed on the via surface by electroless Cu plating. For Cu via filling, the electroplating of Cu from an acid sulfate bath containing typical additives such as PEG(polyethylene glycol), chloride ions, bis-(3-sodiumsulfopropyl disulfide) (SPS), and Janus Green B(JGB) was carried out. The desmear treatment clearly removes laser drilling residue and improves the surface roughness, which is necessary to ensure good adhesion of the Cu. A homogeneous and thick Cu seed layer was deposited on the samples after the desmear treatment. The 2,2'-Dipyridyl additive significantly improves the seed layer quality. SPS, PEG, and JGB additives are necessary to ensure defect-free bottom-up super filling.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.322-329
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• 2021

Nano-cementitious composites may have defects due to poor dispersion of nanomaterials and fabrication process. These defects can cause critical problems for nano-cementitious composites, but studies related to non-destructive analysis of defects sizes inside nano-cementitious composites are insufficient. This study aims to perform non-destructive analysis of nano-cementitious composites by utilizing ultrasonic and electrical resistance. Various sizes of defects were implemented inside the specimens and the specimens were subjected to ultrasonic non-destructive analysis and electrical resistance non-destructive analysis depending on the size of defects and curing days. As a result of the experiment, ultrasonic pulse velocity decreased by up to 11% as the defects size increased, and the electrical resistance increased by up to 14% depending on the defects size. For this reason, this study concluded that non-destructive analysis using ultrasonic and electrical resistance can predict defects inside nano-cementitious composites.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.456-462
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• 2019

ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and $O_2$ mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when $O_2$ is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ${\pm}3V$ of the reverse and forward bias voltage is about $5.8{\times}10^3$, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.