• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.185-195
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• 2015

Glucoamylase is an important industrial enzyme. Glucoamylase production by industrial Aspergillus niger strain featured with two major problems: (i) empirical substrate feeding methods deteriorating the fermentation performance; and (ii) the high raw materials cost limiting the economics of the glucoamylase product with delegated specification. In this study, we first proposed a novel three-stage varied-rate substrate feeding strategy for efficient glucoamylase production in a 5 L bioreactor using the standard feeding medium, by comparing the changing patterns of the important physiological parameters such as DO, OUR, RQ, etc., when using different substrate feeding strategies. With this strategy, the glucoamylase activity and productivity reached higher levels of 11,000 U/ml and 84.6 U/ml/h, respectively. The performance enhancement in this case was beneficial from the following results: DO and OUR could be controlled at the higher levels (30%, 43.83 mmol/l/h), while RQ was maintained at a stable/lower level of 0.60 simultaneously throughout the fed-batch phase. Based on this three-stage varied-rate substrate feeding strategy, we further evaluated the economics of using alternative carbon sources, attempting to reduce the raw materials cost. The results revealed that cornstarch hydrolysate could be considered as the best carbon source to replace the standard and expensive feeding medium. In this case, the production cost of the glucoamylase with delegated specification (5,000 U/ml) could be saved by more than 61% while the product quality be ensured simultaneously. The proposed strategy showed application potential in improving the economics of industrial glucoamylase production.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.383-386
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• 2001

The KS of “Measurements of impact sound insulation of floors” was established before the years. But the KS of “Rating of floor impact sound insulation for impact source in building and of building elements” is not founded yet. To establish the rating measurement of floor impact sound insulation. The studies on the rating method of domestic floor system of impact sound insulation and response of its inhabitant’s were reviewed. And the rating method of ISO’s and JIS’s were studied in this consideration. The result of this study, KS of “Rating of floor impact sound insulation for impact source in building and of building elements” is proposed.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.94-98
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• 1993

This study discusses a possible ergonomics application for adult wheelchair design in consideration of anthropometry, physical load, control ability, posture, subjective analysis, security and so on. Korean normal adults who ever used wheelchairs are examined. And anthropometric data and basic data to make standard wheelchair are provided.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.11 s.242
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• pp.1551-1559
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• 2005

This paper explains manufacturing process and experimental studies on a composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a 40mm-thick aluminium honeycomb core and 5mm-thick woven fabric carbon/epoxy face. In order to evaluate structural behavior and safety of the composite carbody, the static load tests such as vertical load, end compressive load, torsional load and 3-point support load tests have been conducted. These tests were performed under Japanese Industrial Standard (JIS) 17105 standard. From the tests, maximum deflection was 12.3mm and equivalent bending stiffness of the carbody was 0.81$\times$10$^{14}$ kgf$\cdot$mm$^{2}$ Maximum stress of the composite body was lower than 12.2$\%$ of strength of the carbon/epoxy. Therefore, the composite body satisfied the Japanese Industrial Standard.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2713-2722
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• 2000

When designing a gear drive, designers should specify tolerances reasonably considering accuracy, cost, and manufacturing capability. In field design, however, designers mostly assign adequate tolerance without correlations between parts and assembly, resulting in iterative design dependent on experts know-how. In order to resolve this, the tolerance design system for a cylindrical gear drive is developed both to support tolerance design automation and to synthesize design processes of part and assembly tolerances. In this research, part tolerances are designed with the databases constructed by ISO, Ks, JIS and bearing catalogue, Assemble tolerance, that is, backlash tolerance is designed by synthesizing part design tolerances stochastically using the formulated assembly relations. This system can include part tolerance and fitting accuracy of shaft adn bearing in practical design. In addition, this system provides field-designers with a synthetic guideline for tolerance design of a gear drive.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.65
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• pp.31-40
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• 2001

We Propose an improved shovel design to minimize physical discomfort and the risk of cumulative trauma disorder at shoveling tasks. The specifications of shovels in Korean standard data were scrutinized to check if they met the anthropometric specification of Korean population in 1997. We also applied "Body Map" pictograph and self-conscious checklist to field survey to analyze the discomfort of shoveling task. Thirty male subjects whose age were ranging from 18 to 65 voluntarily participated in the experiment. The measurement results show that shoveling workers were exposed to hazards of CTD's. Especially, when workers were involved in ditch digging and construction their trunk vend more than 120 degree. In order to compare the new designed shovel and the traditional K.S shovel, an analysis of variance was performed and we obtained very strong evidence that the new designed shovel was better in reducing physical discomfort. According to the results from electromyograrn experiment the new shovel contributed to improving subjective comfort level and reducing low back muscle fatigue. For futher study, the research may be extended to determine the relationship among shovel sharpness, type, digging motion and digging force.ing force.

• International Journal of Quality Innovation
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• v.9 no.3
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• pp.71-91
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• 2008

The definition of cycle time is the time from the wafer start to the wafer output. It usually takes one or two months to get the product since customer decides to produce it. The cycle time is a critical factor for customer satisfaction because it represents the response time to the market. Long cycle time reflects the ineffective investment for the capital. The cycle time is very important for foundry because long cycle time will cause customer unsatisfied and the order loss. Consequently, all of the foundries put lots of human source in the cycle time improvement. Usually, we make decisions based on the experience in the cycle time management. We have no mechanism or theory for cycle time management. We do work-in-process (WIP) management based on turn rate and standard WIP (STD WIP) set by experiences. But the experience didn't mean the optimal solution, when the situation changed, the cycle time or the standard WIP will also be changed. The experience will not always be applicable. If we only have the experience and no mechanism, management will not be work out. After interview several foundry fab managers, all of the fab can't reflect the situation. That is, all of them will have an impact period after product mix or utilization varied. In this study, we want to develop a formula for standard WIP and use statistical process control (SPC) concept to set WIP upper/lower limit level. When WIP exceed the limit level, it will trigger action plans to compensate WIP Profile. If WIP Profile balances, we don't need too much WIP. So WIP level could be reduced and cycle time also could be reduced.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.298-301
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• 2000

Heavy metals are extracted from stream sediments, roadside soils and sediments and soils and tailings from mining area using partial extraction, acid digestion and HF-digestion. Compared to amounts of heavy metals extracted using partial extraction, those extracted using acid digestion are higher by 2.0∼220.9 times in Cu, 2.4∼2806.1 times in Pb, 1.3∼121 times in Cd, 14.1∼1300885 times in Fe, 1.2∼271.5 times in Mn, 1.3∼372.5 times in Zn, 2.2∼1734.5 times in Cr. Although partial extraction, which extracts less amounts of heavy metals from soil compared to acid digestion, is used in domestic standard method for examination of soil, domestic soil standard for heavy metals in non-agricultural and industrial areas is higher than soil standard in foreign countries which use acid digestion, For improvement of the domestic standard method for assessment of soil, it is suggested to lower the domestic soil standard for heavy metals or to change pretreatment method for extracting heavy metals from partial extraction to acid digestion with modifying the soil standard.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.322-335
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• 2019

Objectives: The goal of this study is to standardize industry, process, and job within work environment measurement information. Methods: We selected 180 work environment measurement reports on 30 industries from a database monitored from 2014 to 2016 by the Korea Industrial Health Association. Ten industrial hygienists, each with over five years of experience in measurement, conducted a primary standardization of 180 reports. Two professional industrial hygienists with more than 20 years of experience each reviewed and revised the results of the primary standardization. We also examined the validity on the usefulness of the standardized database by the two industrial hygienists. Results: The final standardization results were classified into eight major categories, 23 sub-major categories, 39 minor categories, 53 unit categories and 70 sub-unit categories in the Korean Standard Industrial Classification (KSIC) 10th revision. A total of 161 processes were standardized, and there were 148 processes with K2B codes. Standard job was coded into 13 job groups including operator, automobile maintenance, nurse, maintenance, manager, excavating machine operator, forklift driver, radiologist, clinical pathologist, signer, researcher, kitchen assistant, and concrete reinforcement ironworker. Conclusions: Although the standardized information in this study may be only a part of the total information, it can be useful for improvement of the K2B system. Additional research is needed for an ongoing clean-up of data in the K2B and re-calibration and reclassification of standard processes until the future national exposure monitoring system is fully established.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.209-216
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• 2012

Objectives: Polyurethanes are usually formed by the reactions of liquid diisocyanate components with liquid polyol resin components. Although polyurethanes have advantageous properties, such as their versatility, the manufacturing process generates diisocyanates, which can cause asthma and respiratory irritation in exposed workers. This study compared the differences in diisocyante concentrations between two different (molded foam and slabstock foam) polyurethane foam manufacturing methods. Materials and Methods: Active samples and direct reading samples of diisocyanates (MDI, TDI) were collected in five polyurethane foam manufacturing companies. Results: Workers' exposure concentrations of diisocyanate (GM: 4.078 ppb, range: 1.190~23.770 ppb) in a slabstock foam manufacturing company were much higher than those (GM: 0.011 ppb, range: 0.001~0.055 ppb) in molded foam manufacturing companies. The results of the direct reading samples of diisocyanate indicated that the rapid reaction zone of the slabstock foam processes emitted large amounts of diisocyanates. Conclusions: The exposure levels of diisocyanates for all molded foam workers were much lower than the occupational exposure standard (5 ppb); however, exposure levels for many slabstock foam workers exceeded the standard.