• Journal of Advanced Marine Engineering and Technology
• /
• v.19 no.4
• /
• pp.7-16
• /
• 1995

This article describes the working prnciple, structure and main characteristics of vacuum coolers for vegetables, and gives concrete examples of vacuum coolers that srebeing put to practical use. In particular, newly-developed cavuum coolers with cold storage, utilizing night-time electricity, are focused upon. Processing plants for vegetables, cold-storage rooms and vacuum cooling devices were investigated as possible application of vacuum cooling technology.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1261-1266
• /
• 2008

Experimental study was performed to understand the operations of a showcase working in a discount store. Temperatures of evaporation, condenser were measured and also electric power consumption of compressor were measured. The purpose of this study is to application use of cold-heat storage systems operated the showcase. At the condition using ice storage system, the ice making process was operated during midnight being not needed the cooling of the showcase through the continuous running of the condenser unit. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, hence the running time of the compressor was effectively decreased. In other words, this study showed that power consumption during daytime can be transferred to the midnight for making use of the refrigerant sub-cooling. So the operating characteristics of the showcase system under various working conditions were analyzed and discussed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1323-1326
• /
• 2003

In this paper, we propose set-up model of silicon steel cold rolling mill. Until now, the working of Silicon Steel is operated using the look-up table value of roll force which a field operator finds by making good use of his experience. Therefore, the standardization of data and an improvement of the quality on product are very difficult. So we establish neural model using field data of various kinds of coil at each pass.

• Transactions of Materials Processing
• /
• v.6 no.3
• /
• pp.221-226
• /
• 1997

Chevron crack in cold extrusion has been studied in view of deformation conditions and material characteristics. There is V formed chevron crack is occasionally occurred in core part of shaft by multistage free extrusion. Although many research results were reported and theoretical analyses were accompanied, in this study we discussed practical method to prevent chevron crack in the field of working conditions and material characteristics. We have found that chevron crack is eliminated under condition of high hydrostatic state in deformation and decreased segregation, refinement of micro structure of materials.

• Journal of dental hygiene science
• /
• v.10 no.6
• /
• pp.459-464
• /
• 2010

The purpose of this study was to evaluate the physical properties of hydrophilic polyvinyl siloxane impression materials as change of material's storage temperatures. Working time, strain-in-compression, elastic recovery and consistency were tested according to ISO Standard NO. 1563. The results are as followed. 1. Working time decreased in cold storage. 2. Strain-in-compression was different in storage temperatures. Material's strain-in compression in cold temperatures were higher than in room temperature and in incubator. 3. A coefficient of elastic recovery varied by storage temperatures. The rate in cold temperature was the lowest and in incubator was the highest. 4. Consistency of impression substance different in storage temperatures. The extent in cold temperature is the highest and in incubator was the lowest. Statistical analysis(SPSS 14.0k, p>0.05) showed that storage temperature affect to material's physical properties. We recognized that the physical properties of polyvinyl siloxane impression materials were changed according to storage temperature.

• Steel and Composite Structures
• /
• v.12 no.6
• /
• pp.465-489
• /
• 2012

Residual stresses play important role for design of steel structural members. Cold formed sections usually have residual stresses caused by roll forming. When compared to stresses caused by the working load, especially for compressed members, the effects of residual stresses can be favorable or unfavorable depending on magnitude, orientation and distribution of these stresses. The research presented in this paper includes experimental investigations of residual stresses, initial imperfections and material properties on cold formed carbon steel open cross sections. Experimental results have been compared to results obtained in similar tests with stainless and high strength steel cross sections. Theoretical and experimental research, conducted for cold formed open cross sections, are important for design of axially compressed members. This paper presents two methods of residual stresses investigation: magnetic method and method of pre-drilled holes and obtained results have been compared with results of residual stresses from other authors.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.9
• /
• pp.145-151
• /
• 1998

In this study, the experimental and analytic investigation with cold air system has been performed for improving the working environment of the conventional grinding fluid. Very simple cold air system was developed which could replace by the conventional grinding fluid system. The identification of heat of grinding Bone is very important for precision grinding. The experimental data was analysed to investigate the heat which was transferred to the workpiece. It was found that 45∼55％ of the total energy for dry grinding, 22∼28％ for wet grinding, and 32∼35％ for cold air system are conducted to the workpiece in grinding with cubic boron nitride wheel. Cubic boron nitride wheel could reduce the residual stress and thermal demage comparing with aluminium oxide wheel, because cubic boron nitride wheel has very high extreme thermal conductivity.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.5
• /
• pp.622-629
• /
• 2007

Some worker is occupationally exposed to cold and freezing environment. The cold stimuli in the working environment impose physiological and psychological loads on workers to decrease the task performance. The purpose of this study is to investigate the cold stimuli of cold and freezing stores widely used in Busan can make an effect on human's physiological responses and task performance, experimentally and analytically. In the experiment, 5 workers are selected as subjects, and then their skin temperatures of hand and ear, heart rates, blood pressure, and ring test performances in cold($3^{\circ}C$) and freezing($-22^{\circ}C$) stores were measured for 21 minutes and analyzed by using statistical method. It is observed that a physiological variation and the task performance are significantly influenced by an exposure time as well as a strength of cold stimuli. Also, it is suggested the exposure limiting times for the useful manual work and the performance predict model of the ring tasks. The result of this study will be useful for a fundamental data of which design the standard task time of manual tasks and solve the job placement problem of worker selection and placement in cold environment.

• Journal of Technologic Dentistry
• /
• v.17 no.1
• /
• pp.26-40
• /
• 1995

A survey has been performed for the dental technicians and office workers in small cities of Julla buk-do on theis problem of cough, phlegm, wheezing, nasal cattarrh & cold, and breathlessness by using SUN-81-AL survey form which is a guletionaire on respiratory symptons The results of the analysis are as follaus. 1. The complaint on cough was made by 15 dental technicians(21.4% and by 10 office workerr(16.7%). Dental technicians showed higher complaint on cough than office workers. The predietor variable for cough was the working hours for dental technicians and the period of smoking for the office sorkess. 2. The complaints on phelgm was made by 34 dental technicians(48.6%) and by 9 office workers(15.0%). The predictor variable on phelgm was the working hour for dental techniume and the period of smoking for the office workers. There was no statistically significant difference between two group on their complaint level. 3. The complaint on the breathlessnesr was made by 24 dental technicians(34.3%) and by 22 office workers(36.7%). The predictor variable on breathlessness was the period of smoking for dental technicians and the working hour for office workers. 4. The wmplaing on nasal catarrh & cold wax made by 29 dental technicians(41.4%) and 22 office workers(36.7%). The predictr variable on nasal catarrh & cold was the working hour for dental workerr, and the perird of smoking for the office workers. 5. The complaint on wheezing was made by 9 dental technicians(12.9%) and 8 office workers(13.3%). The primary predictor variable on wheezing was the working hour for both groups, and the secondary predictor variable was the period of smoking. 6. The complaint on the chest and lung dislase was made by 12 dental technicians(17.1%) and 4 office workers(6.7%) dental technicians showed bigher complaint. on chest and lung disease than the office workers. Bronchitis was the higher frequency illuess reported from both of the groups among chest and lung disease. 7. In conclusion, the predictor variable on respiratory illness was the working hour for dental techniciane, and the period of smoking for the office workers 8. 25 dental technicians(35.7%) and 9 office workers(15.0%) selected air pllution as the most urgent problem that working environment, has had. There was statistically significant difference between two groups(P<0.001)

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.17 no.1
• /
• pp.49-55
• /
• 2021

In this paper, an application example for fitness-for-service of material is shown. A kind of instrument valve is made of austenitic stainless steel fabricated by the cold working process. The tensile strength of the cold worked austenitic stainless steel has to be limited under 90 ksi to prevent the stress corrosion cracking in power plants. In industrial fields, tensile strengths of some materials were discovered to be over the regulation requirements in a certified material test report (CMTR). Owner's verification tests were performed to compare with that in a CMTR and to check the appropriateness. It is found that, in the case of verification test under the required test speed, valve materials could be used in the field. Although it is only one application sample of material check process in the power generation site, this case study could show an importance of basic experimental technology in academia and research circles.