• Journal of the Korean Applied Science and Technology
• /
• v.3 no.2
• /
• pp.17-22
• /
• 1986

Compositional and quantitative changes of 4-desmethylsterols in soybean (Glycine max. cv. Gangrim) seed and pod at six stages of development from flowering were investigated. The content of 4-desmethyl-, 4-monomethyl- and 4,4-dimethylsterols in developing soybean seed and pod was found to vary between 0.16-0.35, 0.04-0.12 and 0.04-0.06%, respectively. The predominating 4-desmethylsterols were sitosterol, campesterol and stigmasterol. The proportion of sitosterol in seed decreased to 57.0% with maturation, while in pod increased up to 88.7%. ${\triangle}^{7,22,25}$ Stigmastatrienol estimated 7.5% was detected in the fully mature seed.

• Journal of Preventive Medicine and Public Health
• /
• v.14 no.1
• /
• pp.97-110
• /
• 1981

This study was conducted in order to investigate the status of harmful working environ ment on twelve rubber and ten chemical products manufacturing industries in Busan area over a period of five months from lune 1 to October 31, 1980. The summarized results were as follows: 1. The highest and lowest mean values of harmful environmental elements in workroom of rubber products manufacturing industries were noted in twisting (98.7dB) and coating department (77.3dB) to noise, molding ($6.43mg/m^3$) and forming ($1.33mg/m^3$) to dust, bonding (toluene 463.7ppm, xylene 457.8ppm and benzene 111.8ppm, respectively) and splicing (toluene 90.0ppm, xylene 83.3ppm and benzene 6.7ppm, respectively) to organic solvents, respectively. Also in chemical products manufacturing, they were noted in grinding (95.1dB) and shining department (76.8dB) to noise, packing ($4.30mg/m^3$) and staining ($3.20mg/m^3$) to dust, shining (393.3ppm and 375.0ppm, respectively) and varnishing(125.5ppm and 121.7ppm, respectively) to toluene and xylene, and scattering (51.8ppm) and mixing (23.9ppm) to benzene, respectively. 2. The mean values of harmful elements in workroom of rubber products manufacturing were 86.3dB to noise, $4.16mg/m^3$ to dust, 258.2ppm to toluene, 230.3ppm to xylene, and 5 4.0ppm to benzene, respectively. Also in chemical products manufacturing, they were 85.2dB to noise, $3.69mg/m^3$ to dust, 227.9ppm to toluene, 213.2ppm to xylene, and 36.3ppm to benzene, respectively. 3. Number of workers exposed to harmful working environment, over TLV, of a total 10,195 workers in rubber products manufacturing were 1,002(9.8%) to noise, 212 (2.1%) to dust, 1,581(15.5%) to toluene, 1,509(14,8%) to xylene, and 1,524(15.0%) to benzene, respectively. Number of workers exposed to harmful working environment, over TLV, of a 1,913 workers in chemical products manufacturing were 112(5.9%) to noise, 132(6.9%) to each organic solvent, respectively. 4. The values of noise and dust of rubber and chemical products manufacturing in 1980 were lower then those in 1977, but the value of organic solvent in 1980 was similar with that in 1977.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.6 no.2
• /
• pp.249-264
• /
• 1996

This study was conducted for the purpose of obtaining the fundamental data on improvement of working environment and contributing to health improvement of workers who dealed with metal by assessing the metal concentration in air of industries located in Chang-Won Industrial Complex. Authors measured the concentration of metals(Al, Cd, Cr, Cu, Mn, Ni, Pb, Sn and Zn) is the air to 25 working processes of 73 industries by flame atomic absorption spectrometry from February to December 1994. Personal air sampler was used for air sampling with mixed cellulose-ester membrane filter. The results were as follows : 1. The geometric means(range) of metal concentration; 1) Al: $0.1505mg/m^3$ ($0.0147-18.6100mg/m^3$) 2) Cd: $0.0077mg/m^3$ ($0.0003-7.0710mg/m^3$) 3) Cr: $0.0163mg/m^3$ ($0.0013-1.1510mg/m^3$) 4) Cu: $0.0097mg/m^3$ ($0.0009-0.4950mg/m^3$) 5) Mn: $0.0412mg/m^3$ ($0.0006-4.7877mg/m^3$) 6) Ni: $0.0088mg/m^3$ ($0.0001-1.0170mg/m^3$) 7) Pb: $0.0152mg/m^3$ ($0.0015-0.4499mg/m^3$) 8) Sn: $0.0486mg/m^3$ ($0.0037-0.1500mg/m^3$) 9) Zn: $0.1911mg/m^3$ ($0.0122-8.2920mg/m^3$) 2. The geometric mean of lead exceeded TWA in assembling process of other general purpose machinery not elsewhere classified products manufacturing industries.

• Journal of the FoodService Safety
• /
• v.3 no.1
• /
• pp.38-44
• /
• 2022

This study investigated the microbiological hazards in the manufacturing processes of Naengmyeon. Sanitary indicative bacteria, such as aerobic plate counts and coliforms as well as pathogenic bacteria, were examined from raw materials, manufacturing processes, working area, 17 utensils and equipment. The aerobic plate counts for raw materials and arrowroot starch estimated as 0.77±0.68~5.02±0.28 and 5.02±0.28 log CFU/g, respectively. Coliforms were detected from wheat flour, buckwheat flour, and potato starch. Staphylococcus aureus was detected to be 0.61±1.06 log CFU/g in wheat flour and 0.20±0.35 log CFU/g in buckwheat flour. During the manufacturing process, aerobic plate counts for kneading process were 4.54±0.34 log CFU/g. But after the press out and heat process, contamination of aerobic plate counts and coliforms decreased and remained at a low level until the release process. Aerobic plate counts before washing disinfection of screw were 3.28±0.62 log CFU/100 cm², the level of which was high in utensils and equipment that had contact with employees or water. These results represent not only an important indicator for the hygienic level but also a scientific basis for analyzing biological hazards, which lead to the introduction of HACCP for the production of safe and hygienic cold noodles processed by manufacturers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.12
• /
• pp.2491-2502
• /
• 2015

Main issue for embodiment of smart factory in small-medium manufacturing business(SMMB) is to whether might be successful or not in achieving a goal, exact materializing for smart factory related technology, and in seeking possible solutions for limited capacity to invest and develop technology. It is required for effective driving of manufacturing innovation 3.0 paradigm that ensures expertise to push forward technology policy based on value chain level of SMMB, and ensures detailed action plans by investment priority and development of core technology against global trend. This paper focuses to suggest countermeasure strategy and task through analysis of advanced technology and patent trend about industrial IoT(IIoT) and cyber physical system(CPS), and support embodiment of smart factory in underlying manufacturing innovation 3.0 scheme.

• Journal of radiological science and technology
• /
• v.41 no.1
• /
• pp.53-60
• /
• 2018

The purpose of this study was investigating the effect of 3D printing technology that changes the speed of sound (SOS) and the broadband ultrasound attenuation (BUA) by controlling the density of the media phantom. We used 3D printers which called additive manufacturing (AM) by using material with polylactic acid (PLA). The inside of the medium phantom was filled crossly with 100%, 90%, 80%, 70%, 60%, and 50% of the material. The ultrasonic instrument measured the SOS and the BUA using a 0.55 MHz ultrasound output in opposing mode with a pair of transducers. As a result, the density of the medium phantoms with the SOS showed very high correlation (r = 0.944), but the SOS showed very low correlation (r = 0.500). It is expecting that the manufacturing and measurement method of the medium phantom using 3D printing technology will be used as basic data for ultrasonic bone mineral density.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.21 no.3
• /
• pp.177-183
• /
• 2011

Occupational exposure to silicon carbide dust of manufacturing industries has seldom been evaluated in Korea. Accordingly, we evaluated various silicon carbide dust concentrations in the breathing zone of workers between May 2010 and July 2010. To compare silicon carbide dust concentrations, three dust samplers including the Institute of Occupational Medicine (IOM) sampler, 37mm cassette sampler, and Aluminum cyclone sampler were used. A total of 5 manufacturing industries producing abrasive and refractory materials using silicon carbide were investigated. The geometric mean concentrations were 2.04, 0.97, and $0.48mg/m^3$ in inhalable, total and respirable silicon carbide dust, respectively. The geometric mean concentrations of silicon carbide in abrasive material manufacturing industries were slightly higher than that of refractory manufacturing industries, and finishing operations were higher than that of other operations. It was found that the results of exposure assessment in airborne dust at manufacturing industries using silicon carbide in Korea showed exceeding rate to American Conference of Governmental Industrial Hygienists Threshold Limit Value ($3mg/m^3$) was 10% in respirable dust samples. Therefore, with the consideration of the close relationship between smaller dust size and the occurrence of occupational respiratory diseases, it is suggested to promulgate the new occupational exposure limit for respirable silicon carbide dust.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.7
• /
• pp.34-42
• /
• 2022

Minimizing the backlash of gears and reducers is important for their proper and precise functioning. In this study, an automatic backlash measuring system was developed for the mass production and quality control of a military-grade reducer. The developed automatic backlash measurement system eliminates human error during the backlash measurement process. It also reduces the manufacturing time and digitizes the backlash number. The system was tested for an aircraft machine gun control reducer that required low-torque and high-precision conditions. The test results show that the torque range was 0.820-4.788 Nm. The maximum torque error is less than 0.231 N·m at 2.943 N·m, and 1.2 arcmin of the maximum backlash error with ± 0.3 arcmin of repeatability. The developed system satisfies all required conditions: torque of 1-3 Nm, torque accuracy within ± 0.5 N·m, and backlash accuracy of ± 3 arcmin.

• Journal of Technologic Dentistry
• /
• v.45 no.2
• /
• pp.31-38
• /
• 2023

Purpose: This in vitro study aimed to compare the trueness of 3-unit fixed dental provisional prostheses (FDPs) fabricated by three different additive manufacturing and subtractive manufacturing procedures. Methods: A reference model with a maxillary left second premolar and the second molar prepped and the first molar missing was scanned for the fabrication of 3-unit FDPs. An anatomically shaped 3-unit FDP was designed on computer-aided design software. 10 FDPs were fabricated by subtractive (MI group) and additive manufacturing (stereolithography: SL group, digital light processing: DL group, liquid crystal displays: LC group) methods, respectively (N=40). All FDPs were scanned and exported to the standard triangulated language file. A three-dimensional analysis program measured the discrepancy of the internal, margin, and pontic base area. As for the comparison among manufacturing procedures, the Kruskal-Wallis test and the Mann-Whitney test with Bonferroni correction were evaluated statistically. Results: Regarding the internal area, the root mean square (RMS) value of the 3-unit FDPs was the lowest in the MI group (31.79±6.39 ㎛) and the highest in the SL group (69.34±29.88 ㎛; p=0.001). In the marginal area, those of the 3-unit FDPs were the lowest in the LC group (25.39±4.36 ㎛) and the highest in the SL group (48.94±18.98 ㎛; p=0.001). In the pontic base area, those of the 3-unit FDPs were the lowest in the LC group (8.72±2.74 ㎛) and the highest in the DL group (20.75±2.03 ㎛; p=0.001). Conclusion: A statistically significant difference was observed in the RMS mean values of all the groups. However, in comparison to the subtractive manufacturing method, all measurement areas of 3-unit FDPs fabricated by three different additive manufacturing methods are within a clinically acceptable range.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.3
• /
• pp.164-170
• /
• 2016

A proposed pneumatic cylinder-driven roll feeder and an air press were designed to be operated automatically by a PLC. The accuracy of the intermittent feed pitch of the roll feeder was evaluated by measuring lengths of cut-offs of a strip stock by a digimatic vernier caliper. At each predetermined feed pitch, the proposed roll feeder was tested 100 times by varying the feed/cut intervals as 2.0/1.5, 3.0/2.0, and 3.5/2.5 s as test sets. The lengths of the cutoffs of the strip stock ranged from 9.89-10.34, 12.1-12.65, and 15.21-15.67 mm at the predetermined 10, 12, and 15 mm feed pitch, respectively, among the total of 300 samples in each feed pitch, regardless of the feed/shear interval. Therefore, the feed/cut interval at each selected feed pitch was found to have no effect on the accuracy of the intermittent advancing of the strip stock.