• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2052-2053
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• 2008

High voltage motors are the core equipment of electric generation facilities and need to guarantee stable operation. Therefore, keeping healthy state is of importance by means of insulation diagnosis periodically. However, if the diagnosis went through in the different circumstances such as temperature, humidity, and impedance applied to the test equipment, the trend analysis have no significance. This paper presents the experimental results supporting the importance of keeping the same conditions under insulation diagnosis.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.89-94
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• 2008

Purpose: To observe the high temperature creep test and the fracture surface of the samples of 9% Ni alloy steel generally used for all kinds of mahine parts and predict the durability of that by determining a constant of C with a Larson-Miller variable. Methods: The equipment of this test was made into lever-beam style designed by Andrade and F. Garofalo et al.. The condition of creep test was set under 16 kinds of conditions after fixing 4 kinds of temperature condition and 4 kinds of stress condition to check how it effects the samples. Results: The temperature of creep test was increased, the stress index (n) of creep deformation was gradually decreased from 3.97 to 3.55. The activation energy of creep deformation was decreased from 90.39 to 83.64 kcal/mol when the stress was increased. A constant of C value by calculation of larson-Miller variable was about 22 and if temperature for use is suggested, the durability could be calculated. Conclusions: By analyzing the fracture phenomenon and suggesting the observation result of the fracture surface of the samples and creep test of 9% Ni alloy steel, the basic design data for the practical use of accessories in the field of equipment could be constructed and used to predict the durability of the equipment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1128-1133
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• 2006

The most important thing to secure safety and reliability of railway vehicles is to verify performance characteristics of equipments, and related companies or research institutes had many efforts to verify performances and functions of equipments synthetically and efficiently. KHST(Korean High Speed Train) has been developed by KRRI (Korea Railroad Research Institute). An electric railway system is composed of high-tech subsystems, among which main electric equipment such as transformers and converter are critical components determining the performance of rolling stock. We developed a measurement system for on-line test and evaluation of performances of KHST. The measurement system is composed of software part and hardware part. Perfect interface between multi-users is possible. A new method to measure temperature was applied to the ]measurement system. By using the system, fault diagnosis and performance evaluation of electric equipment in Korean High Speed Train was conducted during test running.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.744-748
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• 1989

A newly developed Expert System (ES) for the tuning of thermal power plant control equipment is described. The system is furnished with the rules for controller tuning which were obtained by analysis and arranging the data and knowledge from the experts or tuning records. Based on these rules, automatic tuning or setting of the control parameters is performed in real-time base. The performance of the test equipment, a combination of ES and a boiler simulator, was examined in the automatic tuning test for steam pressure, steam temperature, and load controllers of a constant-pressure once-through boiler model. It was confirmed from the test results that the system is quite promising for future application to actual plants, since the tuning results obtained by the proposed system were similar to those by tuning experts.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.214-215
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• 2005

Naval equipments are installed and used for naval vessel with different environmental conditions comparing to the commercial vessel, for example, high engine power per ship displacement size, severe vibration and shock due to high running speed and explosion from naval gun's bombardment and underwater weapons. Therefore, those equipments must be installed on shipboard with small spaces, high ambient temperature around engine room and which are required be fabricated with high resistances of vibration, shock and heat resources. But in case of commercial vessel, the performances of their recent equipments naval have been improved continuously due to the technology development of domestic shipbuilding and shipboard equipment industries, together with the related fundamental industries i.e, metal, steel and electronic industries, to an international level since 1970. With these results, it became possible to unify the specifications of shipboard equipments for the commercial and military vessels(Dual-Use). In this study, vibration and shock test standards for the commercial and military vessels will be compared and reviewed technically.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.227-232
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• 2004

The failure of geogrids can be defined as an excessive creep strain which causes the collapse of slopes and embankments. In this study, the accelerated creep tests were applied to two different types of polyester geogrids, at 75, 80, 85$^{\circ}C$ by applying 50% load of ultimate tensile strengths using a newly designed test equipment which is allowed the creep testing at higher temperatures. And then the creep curves were shifted and superposed in the time axis by applying time-temperature supposition principles. In predicting the lifetimes of geogrids, the underlying distribution for failure times were determined based on identification of the failure mechanism. The results indicate that the conventional procedures with the newly designed test equipment are shown to be effective in prediction of the lifetimes of geogrids with shorter test times. In addition, the predicted lifetimes of geogrids having different structures at various creep strains give guidelines for users to select the proper geogrids in the fields.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.1-6
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• 2009

Recently power plants and oil refineries are focusing on capacity enlargement for better efficiency through higher temperature and higher pressure. Thickness of boiler tubes becomes lessened due to oxidation and erasion caused by high temperature bums gas flowing over tubes outside. Accordingly, mechanical stress of tubes is increasing and that is a critical factor to make a crack and fracture. To prevent those sorts of accidents, aging assessment for proper periodic repair and replacement should be conducted reliably and reasonably. We performed IIT test on Cr-Mo steel, one of the most heat-resistant materials for facilities in power plants, and we report the test result and the considerable effectiveness of IIT test.

• Journal of Drive and Control
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• v.18 no.2
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• pp.32-37
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• 2021

The piston reservoir is mainly used in hydraulic blow-down system for aerospace engineering. The reservoir is heavy due to both hydraulic cylinder and piston in pressurization. The positive expulsion tank with rubber diaphragm has been mostly applied propellant and fuel tank at low pressure to satellites. To reduce weight, the reservoir that can be used at high pressure with rubber diaphragm was developed. In this research, the prediction of life-time for the rubber diaphragm was implemented through an accelerated life test, as a part of development of new reservoir. Also, the diaphragm was stored in an temperature chamber at the same condition as and operation with hydraulic oil. As a result, the life-time for a rubber diaphragm was successfully evaluated via Arrhenius law and Time-Temperature Superposition based on failure times over temperatures in the accelerated test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.871-877
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• 2015

Deep-sea equipment such as underwater robots and unmanned submersible vehicles, include various machine components and sensors, and it is important that their reliabilities be tested before use in the fields. This is necessary because they are affected by complex extreme-environment conditions, such as high pressures, extreme temperatures, and tidal forces that are present in the deep sea. We require test equipment that can conduct empirical tests in conditions that mimic these complex oceanic environments. In this study, we propose specifications that should be met, and a design plan for the primary components, which should limit their use to a maximum water pressure of 2.0 MPa, water temperature of $5{\sim}60^{\circ}C$, and a maximum flow velocity of 2 m/s. in work-in type underwater combined environment test equipment and. We present test system development procedures to verify the reliability of products and systems used in deep-sea environments.

• Korean journal of food and cookery science
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• v.11 no.3
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• pp.249-260
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• 1995

6 Central commissary and 2 conventional school foodservice operations were assessed in terms of time-temperature relationship and microbiological quality, and monitoring control methods were identified through hazard analysis during the phases of prodution and distribution. 2 conventional schools from Seoul and 6 commissary schools from Kyungkido were participated in the survey. Meals produced in central commissary were distributed to satellites, therefore delivery practices of foods were identified as critical. Microbiological test results for commissary and conventional schools revealed that microbiological quality of foods was mainly related to time-temperature management, types of food, and equipment sanitation not to the foodservice system used. Time-temperature profiles at temperature danger zone (7.2-60$^{\circ}C$) observed were to be related to the following sanitary practices: cooked vegetables were held at temperature danger zone for relatively longer delayed time (15-38$^{\circ}C$: 15-226 min, 7-60$^{\circ}C$: 75-226 min), and same results were observed for deep-fat fried cutlets (15-38$^{\circ}C$: 15-151 min, 7-60$^{\circ}C$: 33-151 min). Menu items with various ingredients and frequent contacts with hands and equipments during the production flow were held at temperature danger zone for longer delaying time than other menu items with brief prodution stages. Based on hazard analysis critical control points, microbiological quality was collectively affected by time-temperature relationships, equipment sanitation, proper cooking methods, and sanitary management competencies of dietitians. Microbiological test results of working equipments and surface of dishes and trays showed that immediate action should be taken. Cutting boards used in central kitchen were also showed similar results of potential dager of cross-contamination. Effective sanitary control methods were urgently needed.