• Journal of the Korean Institute of Gas
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• v.25 no.2
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• pp.52-63
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• 2021

Analysis of risky behavior factors for workers in the manufacturing industry enables effective human error prevention and systemization of an efficient safety management system. This study examines the relationship between the effects of workers' work psychology, work environment, and work deviation factors on risky behavior intentions and the effects of such risky behavior intentions on risky behaviors. Among the small and medium-sized manufacturing industries, the analysis was focused on a survey of 80 workers in the manufacturing and processing industry. Looking at the results, it was found that work psychology and work deviation had an effect on the intention of risky behavior, but the work environment factors corresponding to job satisfaction and workload did not affect the intention of risky behavior. The relationship with colleagues, the degree of satisfaction or dissatisfaction with the job, the degree of importance of the job that the worker feels, and the tightness of time to digest a large amount of work do not affect intentionally inducing dangerous work, but they do affect risky behavior. In the absence of intention, the work environment factor was found to accompany dangerous behavior.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1060-1070
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• 2022

With the development of information technology, the size of the system has become larger and diversified, and the existing role-based access control has faced limitations. Blockchain technology is being used in various fields by presenting new solutions to existing security vulnerabilities. This paper suggests efficient role-based access control in a blockchain where the required gas and processing time vary depending on the access frequency and capacity of the storage. The proposed method redefines the role of reusable units, introduces a hierarchical structure that can efficiently reflect dynamic states to enhance efficiency and scalability, and includes user-centered authentication functions to enable cryptocurrency linkage. The proposed model was theoretically verified using Markov chain, implemented in Ethereum private network, and compared experiments on representative functions were conducted to verify the time and gas efficiency required for user addition and transaction registration. Based on this in the future, structural expansion and experiments are required in consideration of exception situations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1679-1686
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• 2009

Odor sensing system that is electronic nose device and its signal processing technique has potential to become a critical service for the people who require tangibility of sense of smell in the multimedia communication. PCA(Principal Component Analysis) have been used for dimensionality reduction and visualization of multivariate measurement data. PCA is good for estimating importance value by variance of data but, have some limitation for getting meaningful representation from odor sensing system. This paper explain about how to analyze the data of odor sensing system by ICA(Independent Component Analysis). We show that ICA can give better result like sensor drift analysis, dimensionality reduction and data representation by improved discrimination.

• Journal of Internet of Things and Convergence
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• v.5 no.2
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• pp.73-79
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• 2019

Research is underway on services and systems that provide real-time alerts for suffocating gases and potentially explosive materials, but currently smart bend type services are lacking. This study supports real-time identification of explosion hazards due to static electricity in the workplace and immediate elimination of accident occurrence factors, real-time monitoring of worker status and workplace hazards (oxygen, hazardous chemical concentration), and immediate warning and data in case of danger. We propose a method of establishing an accident prevention system through analysis. In this way, various accidents that may occur in industrial sites are monitored using IoT-based intelligent sensor nodes, wireless network technology, data processing middleware, and integrated control system, and real-time risk information at the industrial sites is prevented and accidents are prevented. By supporting a safe working environment, the company can significantly reduce costs compared to post-procurement costs.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.258-264
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• 2003

The present paper studies how to calibrate hydrometer using image process. The method aligns particular scales of hydrometer selected for calibrating the hydrometer with the horizontal plane of the reference liquid automatically without man's operation. Major parts composing the system are CCD camera, frame grabber, stepping motor and image process program. The image process program is composed of a part that locates the meniscus and aligns it with a scale and a part that controls the step motor. To verify the performance of the developed method, this study compares the meniscus and scale observed directly with the naked eye with the result of calibration by the manual calibration method. The differences between the corrections were less than $0.004\;kg/m^3$ with uncertainty of $0.06\;kg/m^3$. These showed that the calibration results of the developed hydrometer calibration using image process nearly equal to manual method.

• Korean Journal of Metals and Materials
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• v.49 no.9
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• pp.678-685
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• 2011

The aim of this study was to determine the effect of applied pressure and sintering temperature on the microstructure and mechanical properties for spark plasma sintering (SPS) from commercial pure titanium (CP-Ti) powders. Spark plasma sintering is a relatively new sintering technique in powder metallurgy which is capable of sintering metal and ceramic powers quickly to full density at a fairly low temperature due to its unique features. SPS of -200 mesh or -400 mesh CP-Ti powders was carried out in an $Ar+H_2$ mixed gas flowing atmosphere between $650^{\circ}C$ and $750^{\circ}C$ under 10 to 80 MPa pressure. When SPS was carried out at relatively low temperatures ($650^{\circ}C$ to $750^{\circ}C$), the high (>60 MPa) pressure had a marked effect on densification and grain growth suppression. The full density of titanium was achieved at temperatures and pressures above $700^{\circ}C$ and 60 MPa by spark plasma sintering. The crystalline phase and microstructure of titanium sintered up to $700^{\circ}C$ consisted of ${\alpha}$-Ti and equiaxed grains. Vickers hardness ranging from 293 to 362 Hv and strength ranging from 304 to 410 MPa were achieved for spark plasma sintered titanium.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.179-186
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• 2021

In this study, we attempted to comparatively analyze the structural characteristics of soot generated from marine engines to review the possibility of recycling crankcase soot by classifying it as exhaust soot and crankcase soot. The annealing procedure was performed in an argon gas atmosphere at 2,000℃ and 2,700℃, and Raman spectroscopy and High-Resolution Transmission Electron Microscopy(HRTEM) were used to analyze the structural properties of the samples. Furthermore, digital image processing techniques were utilized to quantitatively analyze the acquired HRTEM images. The Raman analysis demonstrated a relatively high G/D ratio in the exhaust soot and annealing conditions at 2,700℃. In the HRTEM images, both soot were able to identify similar forms of graphite nanostructures, but there were limitations in that they could not quantitatively derive differences in the degree of graphite depending on the type of soot and annealing temperature. Thus, digital image processing quantitatively analyzed the length and tortuosity of the fringe of the HRTEM image, which is consistent with the Raman analysis. This meant that the exhaust soot had a more graphite structure than the crankcase soot, and that annealing at a higher temperature improved the graphite structure. This study confirmed that both the crankcase soot and exhaust soot can be recycled as a graphite materials.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2057-2064
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• 2014

Thermochemical sulfate reduction (TSR) was conducted in autoclave on the system of crude oil and $MgSO_4$ at different temperatures. Gas chromatography pulsed flame photometric detector (GC-PFPD) was used to detected the composition of organic sulfur compounds in oil phase products. The results of the analysis indicate that with increased temperature, the contents of organic sulfur compounds with high molecular weight and thermal stability, such as benzothiophenes and dibenzothiophenes, gradually became dominated. In order to gain greater insight into the formation and distribution of organic sulphur compounds from TSR, positive ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used in detecting the detailed elemental composition and distribution of them. The mass spectra showed that the mass range of sulfur compounds was 200-550 Da. Four sulfur class species, $S_1$, $N_1S_1$, $O_1S_1$ and $O_2S_1$, were assigned in the positive-ion spectrum. Among the identified sulfur compounds, the $S_1$ class species was dominant. The most abundant $S_1$ class species increase associated with the DBE value and carbon number increasing which also indicates the evolution of organic sulfur compounds in TSR is from the labile series to the stable one. In pure blank pyrolysis experiments with crude oil cracking without TSR, different composition and distribution of organic sulfur compounds in oil phase products were seen from mass spectra in order to evaluate their pyrolysis behaviors without $MgSO_4$. FT-IR and XRD were used in analyzing the products of solid phases. Two distinct crystallographic phases MgO and $MgSO_4$ are found to coexist in the products which demonstrated the transformation of inorganic sulfur compounds into organosulfur compounds exist in TSR.

• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.207-212
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• 2011

In this study, pyramid structured black silicon process was developed in order to overcome disadvantages of using wet etching to texture the surface of single crystalline silicon and using grass/needle-like black silicon structure. In order to form the pyramidal black silicon structure on the silicon surface, the RIE system was modified to equip with metal-mesh on the top of head shower. The process conditions were : $SF_6/O_2$ gas flow 15/15 sccm, RF power of 200 W, pressure at 50 mTorr ~ 200 mTorr, and temperature at $5^{\circ}C$. The pressure did not affect the pyramid structure significantly. Increasing processing time increased the size of the pyramid, however, the size remained constant at 1 ${\mu}M$ ~ 2 ${\mu}M$ between 15 minutes ~ 20 minutes of processing. Pyramid structure of 1 ${\mu}M$ in size showed to have the lowest reflectivity of 7 % ~ 10 %. Also, the pyramid structure black silicon is more appropriate than the grass/needle-like black silicon when creating solar cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.