• Korean Chemical Engineering Research
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• 제60권4호
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• pp.492-498
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• 2022

Process control systems used in most domestic petrochemical corporates today are based on the Windows platforms. As technology leans toward opened environment, the exposure risk of control systems is increasing. However, not many companies are preparing for various cyberattacks due to lack of awareness and misunderstanding of cyber intrusion. This study investigated the extent of how much exposed the petrochemical process control system is to security threats and suggested practical measures to reduce OT cybersecurity vulnerabilities. To identify the cyber threat status of process control systems, vulnerabilities of the Windows platform, a principal cyber threat factor, have been analyzed. For research, three major DCS providers in Korea and the discontinuation of Windows platform of 635 control systems were investigated. It was confirmed that 78% of the survey subjects were still operating in the discontinued windows platforms, and those process control systems were operated in a state vulnerable to cyber intrusions. In order to actively cope with these cyber threats, legal regulations such as designation of critical infrastructure for major petrochemical facilities which is implemented in advanced countries such as the United States are needed. Additionally, it is necessary to take the initiative in eradicating security threats to the process control systems by aggressively introducing security solutions provided from existing DCS suppliers. This paper was submitted to Professor Ko JaeWook's retirement anniversary issue.

• KIPS Transactions on Computer and Communication Systems
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• 제11권6호
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• pp.193-204
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• 2022

In a smart factory environment in a small and medium-sized enterprise (SME) environment, sensors and actuators operating on actual manufacturing lines, programmable logic controllers (PLCs) to manage them, human-machine interface (HMI) to control and manage such PLCs, and consists of operational technology server to manage PLCs and HMI again. PLC and HMI, which are in charge of control automation, perform direct connection with OT servers, application systems for factory operation, robots for on-site automation, and production facilities, so the development of security technology in a smart factory environment is demanded. However, smart factories in the SME environment are often composed of systems that used to operate in closed environments in the past, so there exist a vulnerable part to security in the current environment where they operate in conjunction with the outside through the Internet. In order to achieve the internalization of smart factory security in this SME environment, it is necessary to establish a process according to the IEC 62443-4-1 Secure Product Development Life cycle at the stage of smart factory SW and HW development. In addition, it is necessary to introduce a suitable development methodology that considers IEC 62443-4-2 Component security requirements and IEC 62443-3 System security requirements. Therefore, this paper proposes an application plan for the IEC 62443 based development security process to provide security internalization to smart factories in an SME environment.

• Applied Chemistry for Engineering
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• 제7권1호
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• pp.83-90
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• 1996

The changing shape of absorption and fluorescence spectra will increasing S/D in AO-AOT system decreases and then increases again. The aggregation and disaggreation in AO-AOT system occurres. According to increasing temperature, the absorbance increases in pure AO system. But it gradually decreases in premicellar range(S/D = 10, 20, 50 and 80). The disappearance degree of metachromasy according to the concentration of added salt to AO-AOT system is increased. However, the case of $NaNO_3$is reversed. The order of disappearance degree of metachromasy on cationic salts is $Li^+$, $Na^+$ > $Mg^{2+}$ > $Ca^{2+}$, and the order of it on anionic salts is $Cl^-$ > $SO_4{^{2-}}$ > $NO_3{^-}$.

• Journal of the Korean Institute of Telematics and Electronics
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• 제26권5호
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• pp.46-51
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• 1989

The degradation phenomena induced by hot-carrier injection was studied from the shift of threshold voltage and subthreshold current curve in LDD NMOSFET degraded under different DC stress-biases. Threshold voltage shift ${Delta}V_{tex}$ defined in saturation region was separated into contri butions due to trapped oxide charge $V_{ot}$ and interface traps ${Delta}V_{it}$ generated from midgap to threshold voltage. Under th positive stress electric field (TEX>$V_g>V_d$) condition, the shift of threshold voltage was attributed to the electrons traped ar gate oxide but subthreshold swing was not negative stress electric field ($V_g) condition, holes seems to be injected positive charges so threshold voltage and subthreshold swing were increased.

• Journal of the Korea Society of Computer and Information
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• 제19권11호
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• pp.175-181
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• 2014

This paper suggests O(m) polynomial time heuristic algorithm to obtain the solution for the driver scheduling problem, DSP, that has been classified as NP-complete problem. The proposed algorithm gets the initial assignment of n minimum number of drivers from given m schedules. Nextly, this algorithm gets the minimum total time (TC) using 5 rules of swap and insert for decrease of over times (OT) and idle times (IT). Although this algorithm is a heuristic polynomial time algorithm with O(m) time complexity rules to be find a optimal (or approximate) solution, this algorithm is equal to metaheuristic methods for the 5 experimental data. To conclude, this paper shows the DSP is not NP-complete problem but Polynomial time (P)-problem with polynomial time rules.

• Journal of the Korean Institute of Telematics and Electronics C
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• 제35C권7호
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• pp.59-68
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• 1998

This paper is to develop an algorithm for the unlimited korean speech synthesis. We present the results controlled of prosodic factors with isolated words as aynthesis basis unit int he time domain. With a new pitch-synchronous and parametric speech synthesis mehtod in the time domain here we mainly present the results of controlled prosody factors such a spitch periods, energy envelops and durations and the evaluaton of synthetic speech qualities. In the case of synthesis, it is possible ot synthesize connected words by controlling of a continuous unified prosody that makes to improve the naturalities. In the results of experiment, it also has been to be improved uncontinuities of pitch and zeroing of energy in the junction parts of speech waveforms. Specially it has been to be possible to synthesize speeches with unlimitted durations and tones. So on it makes the noisiness and the clearness better by improving the degradation effects from the phase distortion due to the discontinuities in the waveform connection parts.

• Journal of KSNVE
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• 제3권4호
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• pp.361-371
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• 1993

A psychological experiment is conducted by using the method of selected description to find out appropriate terms for expressing the attributes of sounds. It is true that the term is an important clue to estimate the sensation or emotion of sounds even though it does not directly express them. On the basis of the results, it is found in the subjective impression that adjectives are classified into 8 types of group: "pleasant and bright", "weak", "mild and beautiful", "shocking", "unpleasant", powerful", "dark", and "dull" feeling. Also, it is found that "loud", "noisy" and "annoying" terms have the meaning of "strong, powerful and magnificant", "metallic and clamorous", and "unpleasant and unpleasing" feeling as a meaning Korean language respectively.ot;, "metallic and clamorous", and "unpleasant and unpleasing" feeling as a meaning Korean language respectively.nguage respectively.

• Journal of fish pathology
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• 제13권2호
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• pp.111-119
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• 2000

One hundred and twenty three strains of bacterial flora collected from Kunsan bay and examined for drug resistance to 9 antibiotics. The isolated and examined bacteria were Vibrio spp.(44 strains), Pseudomonas spp.(42 strains), Aeromonas spp.(26 strains), Moraxella spp.(9 strains), Enterobacteria spp.(6 strains), Bordetella spp.(3 strains), Alkaligenesis spp.(3 strains), Staphylococcus spp.(3 strains), and Flavobacterium spp.(2 strains). The drugs used were Ampicillin(AM), Penicillin-G(PM), Rifampicin(RF), Streptomycin(SM), Oxolinic acid (OA), Nalidixic acid(NA), Oxytetracycline(OT), Amikacin(AK), and Enorfloxacin(EF). Forty two strains were found to be sensitive to all drugs. The remaining strains showed resistance to various combinations of drugs. Among the resistant strains were mostly restricted to AM(54 strains/43.9%), PM(47 strains/38.2%), RF(35 strains/28.4%), SM(9 strains), OA(5 strains/ 4.06%), and NA(1 strains/0.8%), in combination at high degree showing 15 different drug resistant patterns. The most frequently showed resistant patterns were AM-PM-RF(16 strains/13.4%), AM-PM(8 strains/6.5%), and PM-RF(7 strains/5.6%). These results suggested that Kunsan bay were contaminated with various strains of highly resistant strains to drugs(AM, PM and RF). These results suggest that high levels of various antibiotics have already been introduced to Kunsan bay. Furthermore it seems that chemotherapy of fish disease has become extremely difficult because of the acquirement of multi-drug resistance to wide range of antibiotics.

• Journal of the Korean Society of Costume
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• 제52권8호
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• pp.151-160
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• 2002

This study implicates that the Danryoung(Formal dress) has been worn by the lady in Joesun dynasty. So far 8 cases of Danryoung excavated has been supposed to be worn by woman. The differences between man and woman's Danryoung is at the 'Somae(sleeve)'and 'Mu(gusset)'. Through those excavated Danryoungs, 'Somae' in Woman's Danryoung was straight and 'Mu' attached in outer layer of dress with rectangular form. From the excavated dresses, Ot-go-reum(strings) coloured violet and wider than man's Danryoung. It was also found as detached. Woman's Danryoung was decorated with gold brocade and excavated with belt. Through the dress and accessories excavated, it was estimated in mid-16C to early 17C. With this respect, it was implicated that Danryoung has changed its style to Wonsam after late 17C.

• Journal of the Korean Institute of Telematics and Electronics S
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• 제34S권1호
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• pp.105-114
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• 1997

The phase retrieval problem is concerned with the reconstruction of a signal or its fourier transform phase form the fourier transform magnitude of the signal. This problem does not have a unique solution, in general. If, however, the desired signal is minimum-phase, then it can be decided uniquely. This paper shows that we can make a minimum-phase signal by adding a delta function having a large value at the origin of an arbitrary one-dimensional signal, and a two-dimensional signal can be uniquely specified from its fourier transform magnitude if it is added by a delta function having a large value at the origin, and finally we can solve a two-dimensional phase retrieval problem by decomposing it into several ine-dimensional phase retrieval problems.