• The Research Journal of the Costume Culture
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• v.27 no.1
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• pp.1-10
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• 2019

Firefighters wear Personal Protective Equipment (PPE) for protection from environmental hazards. However, due to the layers of protective functions, the PPE inevitably adds excessive weight, bulkiness, and thermal stress to firefighters. This study investigated the adverse impact of wearing PPE as an occupational stressor on the firefighter's cognitive functioning. Twenty-three firefighters who had been involved in firefighting at least for 1 year were recruited. The overall changing trend in the firefighter's cognitive functioning (short-term memory, long-term memory, and inductive reasoning) was measured by the scores of three standardized cognitive tests at the baseline and the follow-up, after participating in a moderate-intensity physical activity, wearing a full ensemble of the PPE. The study findings evinced the negative impact of the PPE on the firefighter's cognitive functioning, especially in short-term memory and inductive reasoning. No significant influence was found on the firefighter's long-term memory. The results were consistent when the participant's age and BMI were controlled. The outcomes of the present study will not only fill the gap in the literature, but also provide critical justification to stakeholders, including governments, policymakers, academic communities, and industry, for such efforts to improve human factors of the firefighter's PPE by realizing the negative consequences of the added layers and protective functions on their occupational safety. Study limitations and future directions were also discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.646-652
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• 2011

Recently, lots of automobile part manufacturers try to increase glass fiber content of their plastic parts to improve strength and impact-resistance. For this reason, injection mold requires high hardness and wear-resistant. Laser surface treatment is used to improve characteristics of wear and to enhance the fatigue resistance for injection mold. In this paper, high carbon steel (HP4MA) for injection mold material was heat-treated to harden surface by using high power diode laser (HPDL). To find the process parameters for laser surface treatment of HP4MA, many experiments are carried out as changing the parameters of surface temperature and travel speed of laser. From the results of the experiments, it has been shown that the maximum average hardness is approximately 711~739 Hv when the temperature and the travel of laser are $1,050^{\circ}C$ and 2 mm/sec.

• Tribology and Lubricants
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• v.21 no.4
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• pp.185-192
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• 2005

The press cutter is productive equipment that practically manufactures mechanical components and polymer-based materials such as fabrics, papers, films, leathers, and rubbers into the desired shapes using a press cutting tool. The plate cutting process is one of the primary energy absorbing mechanisms in a grounding or collision event between a press cutter and a material on a die. The cutting mechanism is complicated and involves plastic flows of a plate in the vicinity of the tip, friction between the wedge and the plate, deformation of the plate. In this paper, we studied the effect of friction between cutter and plastic sheet far producing precise and superior products. In this paper, the press cutter is analyzed numerically using MARC finite element program for a optimization design of a press cutter. The FEM computed results show that the maximum von Mises stress is concentrated on the tip of a press cutter, which may lead to the edge wear or impact wear of the sharp cutter. Based on the FEM result and Taguchi's experimental design method, the optimized design model 9 for a press cutter is recommended as a best one.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.377-382
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• 2006

Advantageous features of flash memory are stimulating its exploitation in mobile and ubiquitous related devices. The hardware characteristics of flash memory however place restrictions upon this current trend. In this paper, a cleaning policy for flash memory is proposed in order to decrease the necessary penally for recycling of memory minimizing the degradation of performance at the same time. The proposed cleaning algorithm is based on partitioning of candidate memory regions, to be reclaimed as free, into a number of groups. In addition, in order to improve the balanced utilization of the entire flash memory space in terms of 'wearing-out', a free segment selection algorithm is discussed. The impact of the proposed algorithms is evaluated through a number of experiments. Moreover, the composition of the optimal configuration featuring the proposed methods is tested through experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.8-15
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• 2018

Films with special properties (e.g., water-repellent films, optical films, anti-reflection films, and flexible films) are referred to as functional films. Recently, there has been interest in fine patterning methods for film fabrication. In particular there have been many studies that use a UV nanoimprint process involving a UV curing method. In this paper, a polymer film was fabricated by the UV nanoimprint process with a micro-pattern, and its durability was evaluated by a wear test and a nano-indentation test. The film mechanical properties (such as coefficient of friction, hardness, and modulus of elasticity) were measured. Moreover, the choice of PUA type resin used in the UV nanoimprint process was confirmed to impact the durability of the thin film. Despite making the polymer film samples using the same method and PUA type resin, different coefficient of friction, hardness, and modulus of elasticity values were obtained. PUA 4 resin had the most favorable coefficient of friction, hardness, and modulus of elasticity. This material is predicted to produce a high durability functional film.

• Design & Manufacturing
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• v.16 no.4
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• pp.7-16
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• 2022

A helmet is essential for safety when operating personal mobility. However, user's actual helmet wear rate is low due to the inconvenience of wearing and poor ventilation. In this study, a new helmet structure with improved ventilation for personal mobility devices was designed. To design a new structure with improved breathability compared to the existing helmet while satisfying the safety regulations for the helmet, a generative design method was applied to the shock-absorbing liner of the helmet. In addition, other materials were applied to create a structure with improved ventilation while maintaining safety. The generated design result was verified for shock absorption through simulation. As a result of the study, EPS, the current material was replaced with CFRP and Kevlar, and the structure was changed. This design was judged to satisfy safety regulations against impact. The new helmet structure is expected to improve the helmet usability for personal mobility and increase the helmet wear rate of users.

• Journal of Environmental Science International
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• v.32 no.9
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• pp.627-634
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• 2023

Tire wear particles(TWPs), regarded as a microplastic, is generated in significant quantities each year and exist in various spaces and have a negative impact on the surrounding environment. Particularly, roadside environments fall within the direct influence of TWPs, necessitating proactive investigation for contamination management and response. Therefore, this study aimed to investigate the soil acidity and electrical conductivity(EC) and TWPs in the roadside soil of six sites based on traffic volume. The analysis revealed that the soil in all sites exhibited subacidity, and there were no significant differences in EC. Microscopic and FT-IR analysis revealed the presence of microscopic particles in soil samples that exhibited common visual characteristics of TWPs. In the road with the highest traffic volume, 48,300 TWPs were detected per unit area. Furthermore, a proportional relationship between traffic volume and TWPs particles was established. However, influences other than traffic volume on TWPs particle count within the soil were observed. Therefore, for the management of TWPs contaminated roadside soil, a proactive response is necessary in areas with high traffic volumes. However, in order to effectively address the factors contributing to the generation and dispersion of TWPs, further research is required with a multidimensional approach.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.744-752
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• 2007

Recently a fuel oil of the diesel engine in the ship is being changed with low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine like cylinder liner ring groove of piston crown, spindle and seat ring of exhaust valve are increased with using of heavy oil of low quality In particular the degree of wear and corrosion in between valve spindle and seat ring are more serious compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weld to the valve spindle and seat ring is a unique method to prolong the life of the exhaust valve in an economical point of view In this study. corrosion property of both weld metal zone and base metal was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 5% $H_2SO_4$ solution. in the case of being welded with some welding methods and welding materials to the exhaust valve specimen as the base metal. In all cases. the values of hardness of the weld metal zone were more high than that of the base metal. And their corrosion resistance were also superior to the base metal. The weld metal of A2F(AC SMAW: 2 pass welding with foreign electrode) showed a relatively good results to the corrosion resistance as well as the hardness compared to the ether welding methods and welding materials. Moreover it indicated that hardness of the weld metal by the domestic electrode was considerably high compared to that of the foreign electrode.

• The Research Journal of the Costume Culture
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• v.14 no.3 s.62
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• pp.404-417
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• 2006

The purpose of this thesis, therefore, is to examine the shaping methods and the knitting drafts of sleeve cap in the knitwears which are currently used by the manufacturers; to study the curve forms of sleeves in knitwears by analyzing synthetically the results of investigating the problems of knit wear sleeves; to present the most suitable sleeve cap for the knitwears. As the studying methods, I collected the basic data from the working-level persons of knit wear manufacturers, examined the knitting draft in the knitwears, and from that, made three kinds of comparative experimental garments and one kind of research experimental one as 10G and 16G. In doing so, I showed the sleeve cap suitable for the knitwears with plain stitch after operating sensual evaluation with Liker's 5-point rating measure. The analysis of data was handled with statistics by using SPSS Ver. 12.0; the method of statistics was executed by Frequency Analysis, Trust Analysis, one-way ANOVA, and Duncan test according to each topic of the research. As the result of the sensual evaluation of the experimental garments produced from the study, the research experimental garment looks better than the comparative experimental one in both 10G and l6G; has less extra folds around the front part of sleeve cap; looks more natural in sleeve caps of the body part and of a sleeve. From this, I am able to figure out that the research experimental garment looks better than the comparative experimental one produced by knit wear manufacturers. In addition, I can come to know that the different knitting of the front line and the back one of armhole in the knitwears has a favorable impact on improving the appearance of a sleeve.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.310-316
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• 2010

Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. In this case, filler metals having a high corrosion and wear resistance such as stellite 6, Inconel 625 and Inconel 718 are mainly being used for repair welding. However it has been often happened that piston crown on the ship,s job site is being actually inevitably welded with mild filler metals. Therefore in this study, filler metals such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal, and corrosion property of their weld metals in the case of post weld heat treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 0.1% $H_2SO_4$ solution. Corrosion resistance of the weld metal of E4301 was better than the other weld metals in the case of no heat treatment, however, its resistance was considerably decreased with post weld heat treatment(annealing:$625^{\circ}C$, 2 hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by post weld heat treatment.