• Current Optics and Photonics
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• v.6 no.3
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• pp.244-251
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• 2022

We introduce a spectral reconstruction method to enhance the spectral resolution in a static modulated Fourier-transform spectrometer. The optical-path difference and the interferogram in the focal plane, as well as the relationship of the interferogram and the spectrum, are discussed. Additionally, for better spectral reconstruction, applications of phase-error correction and apodization are considered. As a result, the transfer function of the spectrometer is calculated, and then the spectrum is reconstructed based on the relationship between the transfer function and the interferogram. The spectrometer comprises a modified Sagnac interferometer. The spectral reconstruction is conducted with a source with central wave number of 6,451 cm^-1 and spectral width of 337 cm^-1. In a conventional Fourier-transform method the best spectral resolution is 27 cm^-1, but by means of the spectral reconstruction method the spectral resolution improved to 8.7 cm^-1, without changing the interferometric structure. Compared to a conventional Fourier-transform method, the spectral width in the reconstructed spectrum is narrower by 20 cm^-1, and closer to the reference spectrum. The proposed method allows high performance for static modulated Fourier-transform spectrometers.

• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.9-21
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• 2024

Static-electricity-induced fires and explosions persistently occur every year, averaging approximately 80 and 20 cases annually according to fire statistics provided by the National Fire Agency and industrial accident statistics provided by the Ministry of Employment and Labor, respectively. Despite the relatively low probabilities of these accidents, their potential risks are high. Consequently, effective risk assessment methodologies and accident investigation strategies are essential for efficiently managing static-electricity hazards in fire- and explosion-prone areas. Accordingly, this study aimed to identify the causal variables essential for accident investigations, thereby facilitating risk assessments and the implementation of effective recurrence prevention measures to mitigate static-electricity hazards in fire-and explosion-prone regions. To this end, industrial accident statistics recorded over the past decade (2012 to 2021) by the Ministry of Employment and Labor were analyzed to identify major fire and explosion incidents and related industrial accidents wherein static electricity was identified as a potential ignition source. Subsequently, relevant investigation reports (63 cases) were thoroughly analyzed. Based on the results of this analysis, existing electrostatic fire and explosion risk assessment techniques were refined and augmented. Moreover, factors essential for investigating electrostatic fire and explosion disasters were delineated, and the primary causal variables necessary for effective risk assessments and scientific investigations were derived.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.5
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• pp.199-206
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• 2023

The current software becomes the huge size of source codes. Therefore it is increasing the importance and necessity of static analysis for high-quality product. With static analysis of the code, it needs to identify the defect and complexity of the code. Through visualizing these problems, we make it guild for developers and stakeholders to understand these problems in the source codes. Our previous visualization research focused only on the process of storing information of the results of static analysis into the Database tables, querying the calculations for quality indicators (CK Metrics, Coupling, Number of function calls, Bad-smell), and then finally visualizing the extracted information. This approach has some limitations in that it takes a lot of time and space to analyze a code using information extracted from it through static analysis. That is since the tables are not normalized, it may occur to spend space and time when the tables(classes, functions, attributes, Etc.) are joined to extract information inside the code. To solve these problems, we propose a regularized design of the database tables, an extraction mechanism for quality metric indicators inside the code, and then a visualization with the extracted quality indicators on the code. Through this mechanism, we expect that the code visualization process will be optimized and that developers will be able to guide the modules that need refactoring. In the future, we will conduct learning of some parts of this process.

• Journal of Power Electronics
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• v.5 no.2
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• pp.109-119
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• 2005

This paper deals with the performance analysis of static compensator (STATCOM) based voltage regulator for self­excited induction generators (SEIGs) supplying balanced/unbalanced and linear/ non-linear loads. In practice, most of the loads are linear. But the presence of non-linear loads in some applications injects harmonics into the generating system. Because an SEIG is a weak isolated system, these harmonics have a great effect on its performance. Additionally, SEIG's offer poor voltage regulation and require an adjustable reactive power source to maintain a constant terminal voltage under a varying load. A three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source inverter (CC- VSI) known as STATCOM is used for harmonic elimination. It also provides the required reactive power an SEIG needs to maintain a constant terminal voltage under varying loads. A dynamic model of an SEIG-STATCOM system with the ability to simulate varying loads has been developed using a stationary d-q axes reference frame. This enables us to predict the behavior of the system under transient conditions. The simulated results show that by using a STATCOM based voltage regulator the SEIG terminal voltage can be maintained constant and free from harmonics under linear/non linear and balanced/unbalanced loads.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.4
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• pp.1-6
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• 2012

This paper presents the extraction and analysis of small-signal parameters of tunneling field-effect transistors (TFETs) by using TCAD device simulation. The channel lengths ($L_G$) of the simulated devices varies from 50 nm to 100 nm. The parameter extraction for TFETs have been performed by quasi-static small-signal model of conventional MOSFETs. The small-signal parameters of TFETs with different channel lengths were extracted according to gate bias voltage. The $L_G$-dependency of the effective gate resistance, transconductance, source-drain conductance, and gate capacitance are different with those of conventional MOSFET. The $f_T$ of TFETs is inverely proportional not to $L_G{^2}$ but to $L_G$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.6-11
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• 2005

In this paper, two types of vertical SIT(Static Induction Transistor) structures are proposed to improve their electrical characteristics including the blocking voltage. Besides, the two dimensional numerical simulations were carried out using ISE-TCAD to verify the validity of the device and examine the electrical characteristics. First, a trench gate region oxide power SIT device is proposed to improve forward blocking characteristics. Second, a trench gate-source region power SIT device is proposed to obtain more higher forward blocking voltage and forward blocking characteristics at the same size. The two proposed devices have superior electrical characteristics when compared to conventional device. In the proposed trench gate oxide power SIT, the forward blocking voltage is considerably improved by using the vertical trench oxide and the forward blocking voltage is 1.5 times better than that of the conventional vertical power SIT. In the proposed trench gate-source oxide power SIT, it has considerable improvement in forward blocking characteristics which shows 1500V forward blocking voltage at -10V of the gate voltage. Consequently, the proposed trench oxide power SIT has the superior stability and electrical characteristics than the conventional power SIT.

• Journal of Sensor Science and Technology
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• v.7 no.2
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• pp.140-146
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• 1998

Methods and systems to remove static electricity are requested necessarily because the static electricity causes a flammable gas explosion, a fire, reduction of production rate in manufacturing VLSI semiconductor device and so on. In this paper, abrasion and dust contaminant of needle electrode are studied experimentally. And, frequencies and pulse durations of a high frequency pulse source were controlled effectively to minimize the abrasion of needle electrode and control generated numbers of ions. As a result, it is verified experimentally that the ion generation of charge neutralizer increases by using a high frequency pulse source.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.902-908
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• 2018

Optimization of the culture medium to maximize menaquinone-7 (MK-7) production by Bacillus subtilis strain KCTC 12392BP in static culture was carried out using statistical experimental methods, including one factor at a time, fractional factorial design, and response surface methodology (RSM). Maltose (carbon source), tryptone (nitrogen source), and glycerol (activator) were identified as the key medium components for MK-7 synthesis by the fractional factorial design, and were selected for statistical optimization by RSM. The statistical analysis indicated that, in the range that was studied, maltose, tryptone, and glycerol were all critical factors having profound effects on the production of MK-7, with their coefficients for linear and quadratic all significant at the p < 0.05 level. The established model was efficient and feasible, with a determination coefficient ($R^2$) of 0.9419. The predicted concentrations of maltose, tryptone, and glycerol in the optimal medium were determined as 36.78, 62.76, and 58.90 g/l, respectively. In this optimized medium, the maximum yield of MK-7 reached a remarkably high level of $71.95{\pm}1.00{\mu}g/ml$ after 9 days of static fermentation, which further verified the practicability of this optimized strategy.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.31-40
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• 2008

Various coding styles for C language have been proposed so far but there has been a lack of synthetic review about them. In this paper, I propose a new C coding style by analyzing coding rules that are included in the representative C coding styles and by adding new coding rules besides them. In addition, I designed an automated C coding style checker named CStyler which was implemented using Lex and Yacc. It is designed to be able to verify unpreprocessed source code as well as preprocessed source code. And I improved its flexibility by being able to add a new coding rule by end user. I think that the new C coding style and coding style checker, CStyler, can be utilized for education and for future research to develop and extend a static analysis tool.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.1
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• pp.23-30
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• 2015

Reflection is a feature of the Java programming language that can examine and manipulate components of program itself. If you use the reflection, you can get an obfuscation effect of Java source because it converts sources into complicated structures. However, when using it, strings of components name of program are exposed. Therefore, it cannot prevent static analysis. In this paper, we presents a method and a tool of interfere with static analysis using reflection. And in this case, exposed strings are encoded using Vigen$\acute{e}$re cipher. Experimental results show that this tool is effective in increasing the overall complexity of the source code. Also the tool provides two types decryption method based on server and local. It can be selected based on the importance of the API because it affects the execution speed of the application.