• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.39-44
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• 2013

There have been large explosions at some chemical plants recently. Accidents in chemical plants have been caused mainly by servicing for maintenance. There is a need to find a key target for effective injury prevention in maintenance. In this paper, facilities were selected as a key target and the risk priority numbers of the facilities were calculated in order to prioritize preventative measures. The research method was based on the followings; the list of the facilities is found through injury analysis. Then, the risk of each facility was calculated by the frequency of accidents and the working day loss through injuries. In addition, the risk of the facilities was calculated again by the frequency and the severity based on knowledge and experience of experts. As a result, the facilities in chemical plant maintenance are ranked in order of high to low risk priority number; reactor, dryer, tank lorry, etc. In the future, special measures and attention should be directed according to the risk priority number during the maintenance of chemical plants.

• Journal of Digital Convergence
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• v.19 no.8
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• pp.345-350
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• 2021

In the explosive development of the beauty industry, skin care workers are negatively affected by their health and work attitudes due to excessive work intensity or excessive working hours, so there is an urgent need to study the working environment and job psychology. To this end, hypotheses were established and the main effects on skin care workers' job efficacy and job satisfaction in connection with manual technique were analyzed. As a result of the study, in the effect of the skin care manual technique on the skin care professional's sense of job efficacy, the scrutiny method had a significant effect, and in the effect on job satisfaction, the flexible method, the gait method, and the vibration method had a significant effect. In the skin care room, research and development of in-depth manual technique according to the purpose and scope of application of the customer is necessary for the skin care professional's job efficacy and job satisfaction as well as customer satisfaction. It is expected that it will be used as a basic data.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.118-131
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• 1995

The shock fracture analysis for the structures of navy vessels subject to underwater explosions or of high speed vessels frequently subject to impact loads has been carried out in two steps such as the global or macro analysis and the fine or micro analysis. In the macro analysis, Doubly Asymptotic Approximation(DAA) has been applied. The three main failure modes of structure members subject to strong shock loading are late time fracture mode such as plastic large deformation mainly due to dynamic plastic buckling, and the early time fracture mode such as tensile tearing failure or transverse shear failure. In this paper, the tensile tearing failure mode is numerically analyzed for the micro analysis by calculating the dynamic stress intensity factor $K_I(t)$, which shows the relation between stress wave and crack propagation on the longitudinal stiffener of the model. Especially, in calculating this factor, the numerical caustic method developed from shadow optical method of caustic well known as experimental method is used. The fully submerged vessel is adopted for the macro analysis at first, of which the longitudinal stiffener, subject to early shock pressure time history calculated in macro analysis, is adopted for the micro analysis.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.131-139
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• 2017

Recently, earthquakes have frequently occurred near Korean peninsula. An experimental study is needed for developing a reinforcing method for seismic strengthening to apply to RC structures. Recently, PolyUrea (PU) as structural reinforcement materials has been receiving great interest from construction industry. The reinforcing effect of PU appeared to be excellent under blast and impact as well as earthquakes. In this study, Flexible Type PolyUrea (FTPU) developed in preceding studies was modified to develop Stiff Type PolyUrea (STPU) by varying the ratio of the components of prepolymer and hardener of FTPU. The material performance evaluation has been performed through hardening time, tensile strength and percent elongation test, pull-off test, and shore hardness test. The experimental results showed that STPU has higher tensile strength and lower elongation than FTPU. Therefore, STPU coating agent can be used for semi-permanent products. By using STPU with Fiber-Reinforced Polymer (FRP) on concrete columns, confinement effect can be enhanced to maximize seismic strength and ductility.

• Clean Technology
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• v.5 no.1
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• pp.49-61
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• 1999

Fenton's oxidation can improve the biodegradability of refractory organic wastewater by generating $OH{\cdot}$ which is one of the most reactive species. Fenton's reagent is used to treat a variety of industrial waste containing a range of toxic organic compounds. But this process cannot be economical because of high chemical cost of $H_2O_2$, ferrous ion solution and high sludge disposal cost. In this study, we proposed a modified Fenton's oxidation process which can reduce the reagent cost and obtain better removal efficiencies with less Fenton's reagents, and have a good potential of sludge recycling. In modified Fenton reaction, ferrous ion solution is adjusted to optimal pH with NaOH. Then it added to the sample and reacted to $H_2O_2$. For the experiment, synthetic wastewater made of phenol, which is one of the typical water pollutants, was used and the ionic strength of this wastewater was controlled by adding $NaHCO_3$. The effects of DO, ionic strength, and $H_2O_2$ dosing methods were investigated. As a result, modified Fenton's treatment efficiencies are better than conventional Fenton's reaction treating leachate and dyeing wastewater. And modified Fenton's treatment efficiencies combined to the sludge recycling for a half of Iron dosage are as good as the conventional Fenton's for a normal Iron dosage.

• Journal of the Korea Convergence Society
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• v.8 no.4
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• pp.199-205
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• 2017

In this study, the design analysis and the explosion welding were made into a clad sheet by the convergence method in order to solve the problem of heat transfer to the guide due to the heating of the 3D printer heating block. The shear strength of the clad plate material was tested and the results were analyzed by thermal analysis, thermal conductivity and thermal imaging. The following conclusions were obtained. 3D modeling of the heating block made of copper and titanium clad plate material The thermal analysis showed that the surface temperature of the filament guide area was lower than the heating block surface temperature. The average shear strength of copper and titanium clad plate material was measured and the average value of 195.6MPa was obtained. The thermal conductivity of the heating block made of copper and titanium clad plate material was measured three times and the average value was $62.52W/m{\cdot}K$. The surface temperature of the heating block made of copper and titanium clad plate material was measured by a thermal imaging camera at a maximum of $107.3^{\circ}C$ and $183.2^{\circ}C$ at the filament guide. The temperature distribution was $89^{\circ}C$ lower than that of the existing filament.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.936-944
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• 2019

Submarines, which have been called an invisible force, are strategic underwater weapon systems that perform missions such as anti-surface warfare, anti-submarine warfare, and high payoff target strikes with the advantage of underwater covertness. A submarine should be able to withstand the hydrostatic pressure of the deep sea. In this respect, the submarine pressure hull, as the main structural system to resist the external pressure corresponding to the submerged depth, should ensure the survivability from hazards and threats such as leakage, fires, shock, explosion, etc. To do this, the initial scantling of the submarine pressure hull must be calculated appropriately in the concept design phase. The shape of the aft transition ring varies according to its connection with the submarine aft end conical structure, pressure hull cylindrical part, and non-pressure hull of the submarine; the design of the aft transition ring should not only take into account stress flow and connectivity but also the cost increase due to the increased man-hours of its complex geometry. Therefore, trade-off studies based on the four different shapes of the aft transition ring are carried out considering both the review of the structural strength through nonlinear finite element analysis (FEA) and economic feasibility by reviewing the estimations of the manufacturing working days and material costs. Finally, the most rational structural aft transition ring shape for a submarine amongst four reviewed types was proposed.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.361-370
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• 2021

Carbon fiber reinforced polymer (CFRP) is one of the composite materials, which has a unique property that is lightweight but strong. The CFRPs are widely used in various industries where their unique characteristics are required. In particular, electric and unmanned aerial vehicles critically need lightweight parts and bodies with sufficient mechanical strengths. Vehicles using the battery as a power source should simultaneously meet two requirements that the battery has to be safely protected. The vehicle should be light of increasing the mileage. The CFRP has considered as the one that satisfies the requirements and is widely used as battery housing and other vehicle parts. On the other hand, in the battery area, carbon fibers are intensively tested as battery components such as electrodes and/or current collectors. Furthermore, using carbon fibers as both structure reinforcements and battery components to build a structural battery is intensively investigated in Sweden and the USA. This mini-review encompasses recent research trends that cover the classification of structural batteries in terms of functionality of carbon fibers and issues and efforts in the battery and discusses the prospect of structural batteries.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.157-163
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• 2022

The demands for Home Meal Replacement (HMR) products are continuously increasing owing to the convenience of instant food and online food delivery. Ready-to-heat (RTH) products have received massive attention in the HMR industry because these products can be easily warmed using a microwave oven. However, the conventional microwave packaging should be opened before microwave heating to prevent bursting or food loss owing to the steam-pressure build-up inside the package. Open packaging might lead to non-uniform food heating and cross-contamination. Therefore, packaging materials that are able to release steam without opening are of interest to the HMR industry. In this study, polylactic acid(PLA)/polyethylene glycol(PEG)/nanoclay composite films were manufactured using an extrusion method as packaging materials with a smart steam-releasing function. The introduction of PEG to the PLA imparted a steam self-releasing feature to the composite films owing to the morphology change of composite films during microwave heating. Further, PEG increased the ductility of PLA, which in turn prevented bursting caused due to the steam-pressure build-up. The uniform dispersion of nanoclay obtained by a twin-screw extrusion led to stronger mechanical properties. Therefore, the smart composite films developed here can be applied as microwave packaging materials with a self-releasing function.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.662-672
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• 2017

Child sexual crimes have increased, but there has been no effective plan to combat this. Films reporting problems, amplify the attentions and propose countermeasures, which leads to changes. The current study examined the audiences' reactions to child sexual crime faction films using text-mining. The analysis of Naver's 2,727 blogs showed realistic words while 3,000 review comments' analysis demonstrated emotional responses. The positive and negative emotional category and degree were also different. In , the higher degree of negative emotions, such as 'angry' and 'unpleasant' appeared frequently. In , only negative emotional worlds were used. On the other hand, 'sad' was the highest ranked word, and the negative level was weak. In , 'good' a positive emotional word solely emerged. The audiences perceived the accidents objectively before release while they expressed their emotions and feelings after watching the movies. caused explosive anger and organized the participating citizens for changes. This movie provided an opportunity to enforce a legislative bill intensifying heavy punishments. The present study is significant in scrutinizing the audiences' diverse emotional reactions and discusses the future direction of society prosecution movies. Based on the text analysis of the audiences' linguistic expressions, a future study will be needed to hierarchically classify the diverse emotional expressions.