• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.735-749
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• 2023

Purpose: The purpose of this study is to derive solutions and prevent similar cases from occurring by analyzing the causes of cracks found in temperature cycling tests of rocket motor. Methods: By combining the results of the current state confirmation test, non-destructive test, domestic and foreign rocket motor comparison test, cutting test, and adhesion test according to the number of times to apply mold release agent, a Cause and Effect Diagram analysis was performed to derive the cause of cracks. Results: Through this study, 26 factors that could cause cracking in rocket motors during temperature cycling tests were identified. Through various additional test results, a total of five causes were identified, including chemical and structural design of the joint between the propellant and stress relief insert, omission of procedure in the manufacturing procedures, natural aging due to temperature, and load accumulation due to temperature changes. The fundamental cause was confirmed to be insufficient consideration of the release properties of the propellant and stress relief insert. Conclusion: During the design process, it was confirmed that this could be solved by structurally or chemically designing the insert so that it does not combine with the propellant, or by applying a mold release agent during the manufacturing process.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.2
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• pp.15-26
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• 2013

The purpose of this study is to offer basic data for designing and making of brassiere with the consideration of the physiological nature of man. Each of 3/4-cup wired upward-support-type Mold Bra of 75 size with basic pad made at three representative domestic companies (A, B and C Company) was selected for analysis of pattern and components. The following is the result of this study. 1. That Company A's bra had the highest cup, relatively narrow width, the widest front-center and the highest front center at front pad. That of Company B had relatively short wing over the base and much difference at the height of cup depending on the presence of wire. That of Company C had low and wide cup, the widest bust span and the front center width, the front center height of front pad, the base length of front pad and the length of wings were observed to be of the figures between those of Company A and B. 2. The Bra of Company A had the biggest front center angle of $6^{\circ}$, while that of Company C had the biggest wing angle of $18^{\circ}$. The Bra of Company B showed the biggest difference of patterns depending on the presence of wire. Those of Company A and C showed very similar shape when wire was inserted. 3. The order of making brassiere is following: making of exterior mold cup${\rightarrow}$ sewing exterior cup and circumference of mold${\rightarrow}$ sewing base and wings${\rightarrow}$ sewing binding tape to base${\rightarrow}$ sewing cup and main pad${\rightarrow}$ sewing binding tape to upper sides and upper part of wings${\rightarrow}$ sewing wire-tape to interior base of cup${\rightarrow}$ inserting of wire inside wire-tape${\rightarrow}$ sewing hook & eye on the back of wings${\rightarrow}$ sewing shoulder string.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.83-89
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• 2019

In the conventional casting and forging method, there is a disadvantage that a mold is an essential addition, and a production cost is increased when a small quantity is produced. In order to overcome this disadvantage, a metal 3D printing production method capable of directly forming a shape without a mold frame is mainly used. In particular, overseas research has been conducted on various materials, one of which is a metal printer. Similarly, domestic companies are also concentrating on the metal printer market. However, In this case of the conventional metal 3D printing method, it is difficult to meet the needs of the industry because of the high cost of materials, equipment and maintenance for product strength and production. To compensate for these weaknesses, printers have been developed that can be manufactured using sand mold, but they are not accessible to the printer company and are expensive to machine. Therefore, it is necessary to supply three-dimensional casting printers capable of metal molding by producing molds instead of conventional metal 3D printing methods. In this study, we intend to reduce the unit price by replacing the printing method used in the sand casting printer with the FDM method. In addition, Ag paste is used to design the output conditions and enable ceramic printing.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.1
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• pp.77-88
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• 2010

In order to ensure good animal health and performance, it is essential to produce forages with high feeding value and good hygienic quality. However, huge amounts of forages consumed by ruminants are contaminated with mold prior to harvest or during storage as hay, straw or silage. These mold can grow in forages only when nutrients are available, correct temperature exist, oxygen is present, and unbound water is available. Fungal 'species can be divided into two groups: field fungi and storage fungi. Field fungi invade the forages while the crop is still in the field, require high moisture conditions, and are such as species of Fusarium, Alternaria, Clodosporium, Diplodia, Gibberrella and Helminthosporium. Storage fungi invade forages during storage and need less moisture than field fungi. These such as species of Aspergillus and Penicillium usually do not occur any problem before harvest. Mold growth can spoil the nutritional aspects of the forages and also results in secondary metabolites that are highly toxic to animal, humans and plants. Moldy feeds are less palatable and may reduce dry matter intake. This, in turn, leads to a reduction of nutrition intake, reducing weight gains or milk production. Performance losses of 5 to 10 percent are typical with moldy feeds. Mycotoxins are toxic substances produced by fungi (molds) growing on crops in the field or storages. While greater than 400 mycotoxins have been chemically identified, the biological or veterinary medical impact of only several mycotoxins is known. Mycotoxins have attracted considerable attention as potential causes for poor performance and health disorders in domestic livestock. They can be carcinogenic, hepatotoxic, hematotoxic, immunosuppressive, estrogenic, or mutagenic. So, feeding moldy forages has adverse effects on animal health and milk consumers. Also, this author reported that rice straw hay was contaminated mycotoxigenic fungi such as Penicillium roqueforti and Fusarium culmorum in Korea. Therefore, it is an urgent need to develop an improved post harvest storage method to reduce nutrient loss and mycotoxin contamination of forages, which will have a positive impact on human health.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.14-20
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• 2020

In this study, the overall states of the airflow when a truck with or without side pairing is driven at a maximum speed of 90 km/h, regulated by domestic law, were investigated through computational fluid dynamics numerical analysis. All the tested models showed that the airflow went under the truck body; specifically, the air did not flow along the underside to the rear of the truck but through the sides of its underside. The drag with the drag coefficient at model 3 was clearly higher than those for the other two models. The results of this study could help to improve the truck performance by reducing its resistance against the air flown from it in driving itself.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.16-17
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• 2018

A few years ago, the rapid degradation of domestic air quality has led to the efforts of exhaust gas policy and fine dust mask, but it is not a fundamental measure. In Korea, photocatalyst will be applied to residential and multi-use facilites to purify indoor and outdoor air. Also, in this study, it is tried to produce exposed concrete that is aesthetically pleasing as well as air purification of indoor by combining with light transparent concrete according to the increasing interest in human indoor living environment. For this purpose, we have developed a block formwork for photocatalysis light transparent concrete and established a suitable manufacturing method for on-site construction.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.253-256
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• 2000

In order to commercialize the low cost composite fabrication technology in the area of domestic aerospace structure field, Resin Transfer Molding process has been considered as an alternative process to replace the high cost autoclave technology. The end part for the development of RTM process is the control rod of flight control system of aircraft. A braided preform was triaxially designed to improve the dimensional stability and mechanical property in the direction of external loads. Through the flow analysis using CVFEM, the resin filling time was calculated and the resin injection method was determined. The results of the flow analysis were directly applied to RTM mold design. The control rod was successfully manufactured by RTM process using internal pressure. The length and outer diameter of the manufactured part are 1148mm and 32mm, respectively.

• Design & Manufacturing
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• v.17 no.2
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• pp.33-41
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• 2023

Metal raw materials and chemical additives, which are raw materials for secondary batteries, are pulverized by the high-speed rotation of the Grinding Disc of the Classifier Separator Mill (CSM). Grinding discs are required to withstand abrasion, corrosion, high-speed rotational force and impact. In order to analyze the stability of domestic and foreign grinding discs, quality tests including surface roughness, surface lubrication, surface state measurement, and surface 3D shape measurement were analyzed. When producing developed products, it shows that excellent products can be produced.

• Design & Manufacturing
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• v.17 no.2
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• pp.42-46
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• 2023

Currently, fossil resources are depleting rapidly. We are looking for energy to replace fossil fuels. They are trying to use electricity to replace internal combustion locomotives. Secondary battery raw materials and chemical additives are pulverized by the high-speed rotation of the grinding disc of the Classifier Separator Mill. Grinding Disc Assembly requires characteristics to withstand abrasion, corrosion, high-speed rotational force and impact. Domestic and foreign grinding discs were analyzed through abrasion resistance, hardness, bending strength, and tensile adhesion strength tests.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.604-613
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• 2015

The objective of this study was to estimate the food quality of commercial boiled-dried Pacific herring Clupea pallasi as a substitute for boiled-dried anchovy. Standards for controlling quality of boiled-dried Pacific herring were suggested based on international (US FDA and CODEX) and domestic (Korean FDA, Standards on Quality of Seafood and Seafood Products, KS) standards for boiled-dried anchovy. The standards included requirements for moisture [less than 30% (less than 35 in very tiny sizes)], water activity (less than 0.85), salinity (less than 10%), water-phase salt (less than 20%), acid-insoluble ash (less than 1.5%), yeast and mold (fewer than 1.0×10³ CFU/g), and different size and breakage (less than 5%). Based on the standards suggested, commercial boiled-dried Pacific herring passed nine levels (all levels) in water activity, acid-insoluble ash, mold and yeast concentrations; seven levels (L-1, 2, 3, 4, M-1, 2, S) in water-phase salt, and three levels (L-1, 3, 4) in the ratio of different size and breakage categories. These results suggest that the quality of commercial boiled-dried Pacific herring is similar to that of commercial boiled-dried anchovy.