• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.47-56
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• 1985

Wasting fiberous residues from the cutting processes of steel materials at an iron-Works were mixed with concrete. The strength and toughness of steel fiber concrete with different steel contents were tested in a laboratory. The test results showed that the steel fiber residues can be used for the reinforcement of concrete. The potential applications of such product include floor constructions for facilities like dairy barns, grain storages, and machinery shops. The test results are as follows. 1. The compressive strengths of steel fiber concrete with one percent steel content by volume were 20 percent greater than that of plain concrete. The treatments also increased the concrete toughness by 96 percent. 2. When applied to tensile forces, the steel fiber concrete showed the increased strengths by 20 percent, and the toughness by 48 percent. 3. The steel content levels greater than or equal to 1.5 percent by volume resulted in the decreases of the compressive and tensile strengths of steel fiber concrete by 10 percent as compared to plain concrete. The concrete toughness increased with the steel contents. 4. The reinforcement effects of steel fiber depend on the quality of fiber material being used. Good steel fiber for concrete reinforcement appears to be uniform in shape and component, fine and long, and round-shaped.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.603-608
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• 2014

In many manufacturing such as the components of airplane and automobile, aluminum alloys(Al2024) which remarkable in low specific gravity and high strength have been utilized effectively. Face milling machining technology for surface roughness quality of workpiece has been applied in these fields. A face milling machining with chamfered throw away type insert tip can produce a perfect flat surface only in theory. But It is impossible because of many unwanted factors, namely, cutting temperature, plastic deformation, dynamic effect, etc. In this paper, experimental investigations are performed to improve surface roughness after high speed machining of Al2024 using qualified face milling cutter body for high speed machining.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.22-29
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• 2011

In this study, the damage mechanism of large scale steam turbine due to water induction was analyzed and recovery characteristics were reviewed. A turbine consists of the rotating rotor and the stationary casing, and the clearance between them is very small for the efficiency enhancement. If water induction, while relatively cold steam or water is introduced into turbine, occurs, the considerable humping is caused at the casing near the initial water induction point and that induces the rubbing between rotor and casing. Finally, it leads to the catastrophic failure. Bowed rotor has the different characteristics in the recovery depending on damage degree. The elastic deformation due to light rubbing is recovered by turning the rotor with 3 rpm under normal operation condition, but most plastic deformation due to rubbing deforms the local microstructure and that results in permanent deformation which could not be recovered under normal operation condition. Bowed rotor has diverse characteristics depending on the recovery method, and the method is empirical and needs the cutting edge technology. Careful recovery treatment of the rotor will eliminate the risks and secure the high quality rotor similar to new rotor. If any critical error is made during the recovery, the rotor would not be recovered permanently and it should be scrapped.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.222-231
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• 2005

Recently, life cycle and lead-time of products have been shortened with the demand of customers. Therefore, it is important to reduce time and cost at the stage of manufacturing trial molds. In order to realize a three-dimensional shape on CAD, the machining process has been widely used because it offers practical advantages such as precision and versatility. However, the traditional machining process needs a large amount of time in cutting a product and the remained material causes trouble such as inconvenience for clarity. In this work, a new rapid manufacturing process using the hot tool, Rapid Heat Ablation process, has been developed to overcome such limitations. While the hot tool moves the predetermined path, the heat of the tool decomposes the remained material. The radius of heat affect ed zone related to process parameters was investigated through experiments to improve the quality of ablated parts. In order to examine the applicability of the proposed process, three-dimensional shapes such as hemisphere and standard test part, wereablatedutilizingtheapparatus.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.184-187
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• 2005

This paper is described about the technique of ultra-precision machining for optical parts in HMD system. Machining technique for PMMA and BK7 with single point diamond turning machining is reported in this paper. The main factors influencing on the machined surface quality are discovered and regularities of machining process are drawn. The purpose of our research is to find the optimum machining conditions fur cutting of PMMA and grinding of BK7. Also, apply the SPDTM technique to the manufacturing of ultra precision optical components of HMD system. Aspheric PMMA lens without a polishing process, the surface roughness of 5 nm Ra, and the form error of ${\lambda}/2\;({\lambda}=632.8nm)$ for reference curved surface 30 mm has been required.

• Korean Journal of Organic Agriculture
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• v.16 no.3
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• pp.259-274
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• 2008

This study was designed to analyze the possibility to enter the Chinese market aggressively by giving light on the factors which have effects on the continuous intention of Shanghai consumers to purchase environment-friendly foods, and the purchase of Korean environment-friendly foods. The objects of analysis were the 209 consumers living in Shanghai, China. As for the analysis method, the frequency, percentage, crossing analysis, $X^2$-test and logistic regression analysis were carried out, making use of SPSS PC+ 13.0. The study results are as follows. Firstly, it was identified that the decisive factors, such as good taste, health of family, freshness, food shop in a department store, international quality authentication, diversity of items and number of family members, had effects on the possibility that the consumers in Shanghai, China would purchase environment friendly foods continuously, showing the meaningful variables. Secondly, as for the decisive factors having effects on the possibility to buy Korean environment friendly foods continuously, it was identified that good taste, health of family, freshness and price cutting were the meaningful variables. Therefore, it is necessary that to set up a export promotion strategy to make the Shanghai consumers get interested in Korean environment-friendly foods and choose to buy the foods.

• Journal of The Korean Society of Grassland and Forage Science
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• v.10 no.3
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• pp.158-163
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• 1990

This experiment was to study the effect of pure mineral nitrogen fertilizing on seasonal distribution of dry matter yield and the advisable mineral nitrogen amounts on grassland. The results were as follows: 1. With longer regrowth periods the absolute dry matter yields and the nitrogen-efficiences due to nitrogen fertilizing increased substantially, whereas the quality declined at the relatively lesser cutting frequencies. 2. The first cut at 3-cut regimes, the first and fourth cut at 4-cut regimes, and the second and last cut at 5-and 6-cut regimes showed the highest nitrogen-efficiency, respectively. 3. By the sigmaformed process of production curve the most efficient mineral N-dressing rate per ha and cut was calculated: 42-56kg N on the 3-cut areas, 39-55kg N on the 4-cut areas, 38-47kg N on the 5-cut areas and 35-48kg N/ha/cut on the &cut areas. 4. In dependence on site and kind of calculation the economical borders were reached with the following dressings of mineral N/ha/cut: 90-100kg on the 3-cut areas, 70-100kg on the 4-cut areas and 50- 90kg on the 5-and 6-cut areas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.841-848
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• 2021

To develop a value-added low-salt fermented seafood with a long shelf-life, we prepared seasoned low-salt fermented Omandungi Styela plicata supplemented with fermentation alcohol (SOE). The SOE was produced by washing and dewatering shelled Omandungi, followed by cutting and salting for 24 h at 0±1℃. The salted Omandungi was seasoned and fermented with garlic, ginger, monosodium glutamate, red pepper, sesame, sorbitol, and sugar, for 7-8 days at 0±1℃. After adding 3-5% fermentation alcohol, the seasoned fermented Omandungi was packed in a polyester container. The salinity, volatile basic nitrogen content, and viable cell count of SOE were 4.8%, 22.1-22.2 mg/100 g, and (1.2-1.9)×10³ CFU/g, respectively. Compared with the control, addition of 3-5% fermentation alcohol inhibited the decrease in freshness, texture degradation, and growth of residual bacteria. Additionally, the SOE showed good storage stability and organoleptic qualities when stored at 4±1℃ for 40 days. The total amino acid content of SOE was 2,186.0 mg/100 g, mainly comprising glutamic acid, aspartic acid, lysine, and phenylalanine. The free amino acid content was 189.0 mg/100 g, and mainly included taurine, glutamic acid, methionine, alanine, and proline.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.96-101
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• 2019

This paper presents a machinability evaluation of Inconel 718 material when using a new uniform-temperature indirect cooling method that incorporates constant-pressure liquid nitrogen (LN2). The flank wear of a TiAlN coated tool used with this indirect cooling system was much lower than that of the tool used with dry machining under all machining conditions. Also, the surface roughness resulting from machining with this indirect method was far less than that of a dry machined surface after the same cutting time. Reduced heat generation and uniform temperature in turning operations play important roles in tool life and surface quality.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.5-9
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• 2021

Comprehensive utilization of sulfur-containing iron tailings (SIT) not only solves environmental problems but also creates certain economic value. The iron element from SIT was enriched by the superconducting high gradient magnetic separation (S-HGMS) technology in this study. In the experiments, the total iron content (TFe) was increased from 26.3% to 60.5% with the total sulfur content (TS) of 5.9% under the optimal parameters, i.e., a magnetic flux density of 0.4 T, a slurry flow rate of 1500 mL/min. The high-quality sulfur-containing material with TFe of more than 60% was obtained, which can be used for preparing high-sulfur free cutting steel. The S-HGMS technology can realize the resource utilization of iron tailings with high added value.