• Journal of the Korean Graphic Arts Communication Society
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• v.31 no.1
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• pp.1-14
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• 2013

Screen printing is a printing method with flexible plate surface characteristics. In addition, since the appearance of electronics industry the screen printing has been demanding high quality and definition. However, Screen printing is a method for taking ink through mesh opening because screen mesh tends to restrict quality of screen printing. In particular, the biggest problem compared with other printing type is halftone reproduction characteristics. Halftone reproduction characteristics for screen printing depend on screen mesh and opening. Dot losses or dot gains are observed through various types of screen mesh because thread of screen mesh interfere with the movement of the ink. Excessive dot losses or gains can affect the tonal range. Furthermore, this problem can result in other problem such as bad contrast and gray balance. Therefore, it is an important factor to use proper screen mesh for halftone screen printing. However, domestic screen printing industry relies on worker's experience in field rather than depending on objective data although standardized specifications and optimal printing conditions are required for screen printing. For this reason, it is important to stipulate standard condition for domestic screen printing industry. Therefore, it was examined to find tonal range by mesh opening in halftone prints process of screen printing used domestic paper and ink in this study. In addition, TVI(Tone Value Increase) characteristic was observed by comparing to the manuscripts and prints of the dot area ratio. Furthermore, contrast value and gray balance were confirmed for each condition of the printout. Conditions for the proper selection of screen mesh screen for the quality of the prints were also examined, compared with the international standard of screen printing, ISO 12647-5.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.101-116
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• 2010

Last printing market is changing to high-quality color prints for web offset printing. But, color image reproduction based on the relative sheet-ped printing compared to the way, web offset printing are falling. Moreover, it's difficult to maintain the quality of the web offset print. The reason is the worker's decision to rely on. Therefore, the quality of prints was no difference in uniformity and objectivity. We have thought the reason, that the physical properties of inks such as fluidity, viscosity and tack. In addition, varies depending on the physical properties of paper, such as thickness, smoothness, roughness and porosity. Therefore, we studied the properties of ink and paper on the relations between the properties used IGT printability tester. This study of domestic web offset printing inks and papers on the relationship between physical properties and printability were studied. So, to improve printability will be used as the basis resources for web offset printing.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.270-279
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• 2009

In order to check a necessity of health control for the laborers who are in use of mixed organic solvents in the printing industries, this study evaluated the use status of mixed organic solvents, health subjective symptoms on the exposure of the solvents, health hazard for each kind of printings for the employees who work for the printing industries located in Seoul and Gyeonggi. The study analyzed 228 sites and 311 people responded of the total 250 sites surveyed from March to September 2007, and obtained the following results; 1) Estimating the exposure of the mixed organic solvents, the study found that estimation of mixture(EM) was different for each kind of printings at a level of significance, excessiveness of EM was 7.5%, the highest, for gravure printing, 5.6% for screen printing, 4.7% for master printing, 2.9% for offset printing. 2) As to the mean scores of health subjective symptoms for each kind of printings, workers in screen printing showed high scores in every subjective symptom, of which symptom of central nervous system was 3.75, the highest, and the difference was statistically at a level of significance(p<0.01). 3) Results of the hazard analysis for carcinogens and non-carcinogens contained in the mixed organic solvents exposed to the workers showed that cancer risk of offset printing workers was $7.8{\times}10^{-9}$ for benzene, the mean cancer risk was $2.02.{\times}10^{-8}$ from Monte-Carlo simulation, and both risks did not exceed the US EPA permissible standard of $1{\times}10^{-6}$. The total hazard indices of the non-carcinogens estimated was 3.523, the highest, for gravure printing, 2.381 for master printing, 1.125 for screen printing, respectively, and all exceeded 1.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.106-112
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• 2022

Additive manufacturing (AM, also known as 3D printing) technology gets attention for various effects in the construction industry. It reveals abilities of process automation, high traceability of resource management, construction period precision improvement, and worker safety. However, unlike the existing construction technology, the development of AM construction process causes trial errors and unpredictable accidents. In the present study, the construction AM process is designed for on-site construction, and it performs with empirical tests. Also, we analyzed the causes of qualitative experimental results.

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.3
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• pp.125-132
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• 2011

Is very simple in tension work of screen mesh for effective printing if worker uses screen mesh of player who desire at screen print process. General method is methods that use mesh of player who want on screen frame as screen plate because tensioned. The single layer screen plate was made from one sheet screen mesh and the double layer screen plate was made from two sheets screen mesh overlapped. The thickness of sensitive emulsion applied to double layer screen plate is more thicker than two time s of thickness of emulsion applied to single layer screen plate. It seems that the sensitive emulsion inserted between an upper layer and a lower layer of double layer screen mesh.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.87-99
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• 2010

The ink which is left by sealed more than 6 months, it clogs head nozzle of machine due to precipitation and coagulation. In addition, if you stop printing about 3~4 hours in the middle of printing work, the head nozzles of printer could be naturally clogged. To prevent of this situation, worker should implement cleaning and checking head nozzle before hands. When the nozzle is clogged in the middle of work, running a head cleaning mode can clear the clogged nozzle. Yet, large amount of waste inks which are passed clogged nozzle will be remained after cleaning. It would be very nice that ink companies take the waste ink back by green marketing, but none of them are doing it currently. The purpose of this research is that making a black water-based recycle ink by waste inks which are left of nozzle clogging or passed expiration date. This recycle ink will improved working environment and reduce cost of disposing waste inks. Furthermore, it is very environment friendly and economical. It is called a recycle ink which is water-based black ink made by waste inks.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.32-42
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• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.2
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• pp.135-144
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• 2001

This study was performed to measure airborne dimethylformamide(DMF), methyl ethyl ketone(MEK) and toluene and their urinary metabolites concentrations and to determine the relationship between airborne and urinary concentration. Airborne samples and their urinary metabolites were measured 98 male workers who work for 8 synthetic leather factories in a portion of Kyoung-In area. Urine samples were collected at end-of-shift to estimate the exposure levels. 1. The concentration of airborne DMF by process was 8.81 ppm for wet-mixing, 15.05 ppm for wet-coating, 6.03 ppm for dry-mixing, 5.58 ppm for dry-coating, 5.37 ppm for printing, and 9.03 ppm for total. There was statistically significant difference by process. Urinary NMF concentrations of wet-mixing, wet-coating, dry-mixing, dry-coating and printing were $90.55mg/{\ell}$, $79.80mg/{\ell}$, $39.86mg/{\ell}$, $25.23mg/{\ell}$, and $38.15mg/{\ell}$, respectively, and total geometric mean was $56.24mg/{\ell}$. There was significant difference by process. 2. The concentration of airborne MEK by process was 1.89 ppm for wet-mixing, 1.96 ppm for wet-coating, 10.33 ppm for dry-mixing, 29.24 ppm for dry-coating, 14.98 ppm for printing, and 4.87 ppm for total. There was statistically significant difference by process. Urinary MEK concentrations of wetmixing, wet-coating, dry-mixing, dry-coating and printing were $0.93mg/{\ell}$, $0.70mg/{\ell}$, $3.29mg/{\ell}$, $3.29mg/{\ell}$, and $1.06mg/{\ell}$, respectively, and total geometric mean was $1.25mg/{\ell}$. There was statistically significant difference by process. Urinary MEK 3. The concentration of airborne toluene by process was 0.35ppm for wet-mixing, 0.42ppm for wet-coating, 2.95ppm for dry-mixing, 11.67ppm for dry-coating, 4.88ppm for printing, 1.24ppm for total. There was statistically significant difference by process. Urinary hippuric acid concentrations of wet-mixing, wet-coating, dry-mixing, dry-coating and printing were 0.24g/g creatinine, 0.21g/g creatinine, 0.34g/g creatinine, 0.52g/g creatinine, and 0.29g/g creatinine, respctively and total geometric mean was 0.28g/g creatinine. There was statistically significant difference by process. 4. No. of exceeded KPEL was 40 workers(40.8%) for DMF(10ppm), 1 worker(1.0%) for MEK(200ppm), and no worker for toluene(100ppm). No. of exceeded KBEI was 62 workers(63.3%) for urinary NMF($40mg/{\ell}$), 29 workers(29.6%) for urinary MEK, 1 worker(1.0%) for urinary hippuric acid. 5. The regression equations were Log(NMF)=0.4094*Log(DMF)+1.3587(r=0.4516) for DMF, Log(MEKU)=0.1859*Log(MEK)-0.0324(r=0.3303) for MEK, Log(HA)=0.2106*Log(Toluene)-0.5685(r=0.4497) for toluene. Synthetic leather factory workers expose to 3 kinds of organic solvents which are DMF, MEK and toluene. Their urinary NMF and MEK levels were higher than their concentration levels through respiratory. It seems that the urinary levels were affected skin absorption for working habit and alcohol intake.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.1-5
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• 2011

In this paper, we introduce knowledge sharing platform for production technology. Surface mount technology (SMT) is one of the important production technologies to fabricate electronic devices. The production technology of the SMT, however, has been propagated from an experienced worker to an inexperienced worker in a manufacturing field. The objective of the knowledge sharing platform is to convert the production experiences like a solder printing knowhow into quantitative values, to construct the database of the process technologies, and to share the technologies systematically via web portal service. In addition, the knowledge sharing platform contains the total production process of mobile products, the information of experts and facilities, and recent R&D output. In this manner, the knowledge sharing platform for production technology could strengthen the technological competitiveness of small and medium manufacturing companies in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.257-261
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• 2022

Additive manufacturing (AM, also known as 3D printing) applied to the construction industry is implemented and verified for various effects since advantages such as high design freedom, improving worker safety, and predictable construction period. However, due to the low maturity compared to the existing technology, studies are underway to solve new problems that occur in the overall of AM technology. In this paper, we confirm the effect of low construction surface flatness on the stacked features in the process of on-site AM construction. In particular, unstable AM features are determined through quantitative analysis by laser scanning, and a construction strategy is proposed for the surface flattening.