• Journal of Advanced Marine Engineering and Technology
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• 제19권4호
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• pp.7-16
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• 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.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1261-1266
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• 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
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1323-1326
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• 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.

• 소성∙가공
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• 제6권3호
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• pp.221-226
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• 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.

• 치위생과학회지
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• 제10권6호
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• pp.459-464
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• 2010

본 연구는 실리콘 고무인상재의 보관온도에 따른 작업 시간과 압축 시 변형율, 탄성회복율, 점조도에 관한 물리적 특성에 대해서 평가하였으며, 다음과 같은 결과를 얻었다. 1. 작업시간은 저온의 온도유지장치에서 보관한 인상재가 실온이나 고온에서 보관한 인 상재보다 유의하게 크게 나타났고(P<0.05), 실온과 고온에서 보관한 인상재는 유의차 가 없었다. 2. 압축변형율은 저온 온도유지장치에서 보관한 인상재가 실온이나 고온에서 보관한 인 상재보다 유의하게 컸으며(P<0.05), 실온과 고온에서 보관한 인상재는 유의차가 없 었다. 3. 탄성회복율은 인상재를 보관한 각 저장온도에 따라 유의한 차이가 있는 것으로 나타 났으며(P<0.05), 온도가 높아짐에 따라 증가하였다. 4. 점조도는 인상재를 보관한 각 저장온도에 따라 유의한 차이가 있는 것으로 나타났으 며(P<0.05), 온도가 높아짐에 따라 감소하였다.

• Steel and Composite Structures
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• 제12권6호
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• pp.465-489
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• 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.

• 한국정밀공학회지
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• 제15권9호
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• pp.145-151
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• 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
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• 제31권5호
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• pp.622-629
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• 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.

• 대한치과기공학회지
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• 제17권1호
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• pp.26-40
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• 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)

• 한국압력기기공학회 논문집
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• 제17권1호
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• pp.49-55
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• 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.