• 한국건축시공학회지
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• 제3권4호
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• pp.87-94
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• 2003

This study is to investigate the temperature hysteresis and development of compressive strength due to the curing conditions and to evaluate the optimum curing condition of test specimens showing the same development of strength to that of real structures in cold weather. The results of temperature curve with curing conditions in mock-up tests showed the trend of decrease plain concrete with insulation form, plain concrete with heating, concrete with accelerator for freeze protection, and control concrete in turn. The strength development of plain concrete of inside and outside of shelter showed the very slow strength gains due to early freezing, but that of concrete with accelerator for freeze protection showed the gradual increase of strength with time. From this, it is clear that accelerator for freeze protection has the effects of refusing the freezing temperature and accelerating the hardening under low temperature. Strength test results of small specimens embedded in members and located in insulation boxes at the site are similar to that of cores drilled from the members at the same ages, thus it is clear that these curing methods are effective for evaluating in-place concrete strength

• Reproductive and Developmental Biology
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• 제30권1호
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• pp.71-74
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• 2006

Hypoosmotic swelling test (HOST) is used for evaluating the plasma membrane function and fertilizing ability in mammal spermatozoa. However, HOS solutions and experimental conditions have not been determined clearly for assessing canine spermatozoa. This study was conducted to examine the HOS solutions and assay conditions, including incubation time (30 to 120 min), storage temperature (4, 17 and $20^{\circ}C$), semen status (fresh and frozen). Maximum spermatozoal plasma membrane swelling was obtained in an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min. The storage temperature and semen status affected the percentage of HOS positive spermatozoa. The HOS test adapted to canine spermatozoa in this study was simple and highly consistent assay with good repeatability. The optimal condition of HOST in canine spermatozoa is an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min regardless of semen storage temperature and semen status.

• 시스템엔지니어링학술지
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• 제16권2호
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• pp.78-86
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• 2020

The environmental tests are one of the key branches of the reliability tests. The purpose of the high/low environmental test of KT-1 Export Version Trainer is not only based on meeting the compliance of the reliability, customer satisfaction, but also for the expansion of its export. Amongst many existing environmental tests, the high and low temperature tests are considered as the two most important tests. The tests are considered and tailored to the high and low temperature methods of MIL-STD-810H. This paper proposes the tailoring processes and the results of High/Low temperature conditions, test procedures, and test profiles for the aircraft. Additionally, this paper is described by considering the view of MIL-STD-810H.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.794-797
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• 2004

In this study, tensile adhesive strength(TAS) test was carreid out for evaluated the effects of temperature conditions (-20, -10, 0, 5, 10, 20, 30, $40^{\circ}C$) on the tensile adhesive characteristics about 4 type waterproofing membranes which were commercially used in bridge decks. And, failure appeariences of waterproofing systems in each temperature after TAS test were observed the sawing surfaces of waterproofing systems for whether or not damaged of waterproofing membranes. Also, correction coefficient of TAS with temperature were calculated using 4 type waterproofing membrane. It could be shown that the higher TAS and shear adhesive strength, the lower temperature, regardless of the type of waterproofing membrane. Temperature sensibility of TAS was especially remarkable in epoxy membrane. Failure type was occurred the ductile failure in $30^{\circ}C\;and\;40^{\circ}C$. From these results, it was shown that if ambient temperature above $30^{\circ}C$ maintains for a long time, waterproofing membrane will be deformed by softening. Otherwise, waterproofing membrane in temperature below $20^{\circ}C$ shown that occurred the brittle failure. From the results of visual observation of cutting surface for specimen, the thin waterproofing membranes shown indented by hot aggregate of the asphalt mixtures. Therefore, it could be known that the specification of waterproofing membrane thickness is necessary by waterproofing membrane type. As temperature change varied with pavement depth, the interface temperature was more important than ambient temperature in TAS test. Now, TAS test results were limited only in $-10^{\circ}C\;and\;20^{\circ}C$ temperature, but correction coefficient of TAS by ambient temperature could be used as a solution to deal with this problem.

• 한국재료학회지
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• 제19권12호
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• pp.692-698
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• 2009

Inconel 718 alloy has excellent mechanical properties at room temperature, high temperature and cryogenic conditions. UTS of base metal is about 900MPa at room temperature; this is increased up to 1300MPa after heat treatment & aging-hardening. Mechanical properties of Inconel 718 Alloy were similar to those shown in the the results for tensile test; mechanical properties of Inconel 718 alloy's GTAW were similar to those of base metal's properties at room temperature. Mechanical properties at cryogenic conditions were better than those at room temperature. Heat-treated Inconel 718, non- filler metal GTAW on Inconel 718 and GTAW used filler metal on Inconel 718's UTS was 1400MPa at cryogenic condition. As a result, the excellent mechanical properties of Inconel 718 alloy under cryogenic conditions was proved through tensile tests under cryogenic conditions. In addition, weldability of Inconel 718 alloy under cryogenic conditions was superior to that of its base-metal. In this case, UTS of hybrid joint (IS-G) at -100$^{\circ}C$ was 900MPa. Consequently, UTS of Inconel 718 alloy is estimated to increase from -100$^{\circ}C$ to a specific temperature below -100$^{\circ}C$. Therefore, Inconel 718 alloy is considered a pertinent material for the production of Lox Pipe under cryogenic conditions.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.59-62
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• 2001

Flow induced vibration in steam generators has caused dynamic interactions between tubes and contacting materials resulting in fretting wear . Series of experiments have been performed to examine the wear properties of Inconel 690 steam generator tubes in various environmental conditions. For the present study, the test rig was designed to examine the fretting wear and rolling wear properties in high temperature(room temperature - 290。C) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of the steam generator tube materials. To investigate the wear mechanism of material, the worn was observed using scanning electron microscopy. The weight loss increase at higher test temperature was caused by the decrease of water viscosity and the mechanical property change of tube material. The mechanical property changes of steam generator tube material, such as decrease of hardness or yield stress in the high temperature tests. From the SEM observation of worn surfaces, the severe wear scars were observed in specimens tested at the higher temperature.

• 대한기계학회논문집
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• 제3권2호
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• pp.43-47
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• 1979

This paper presents the effect of stress relief annealing on mechanical properties in single Vee-groove welding joint. In this experiment, the investigation of annealing effect on mechanical properties of test material carried out by changing the annealing temperature from $600^{\circ}C$ to $900^{\circ}C$ under the given conditions. The results pbtained by this study are as follows: (1) Under the constant welding conditions, the tensile strength of test welded joint decrease in accordance with the increase of annealing temperature. The experimental results show that the reduction rate of tensile strength is about 35.09% of base metal strength. (2) Microhafdness distribution of welded joint bring about the maximum hardness near the bended line of welding joint. (3) Izod impact energy of welded joint in increase in according to the rise of annealing temperature and the peak energy of impact test occurs at $800^{\circ}C$

• 대한수의학회지
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• 제59권1호
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• pp.43-45
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• 2019

To establish appropriate conditions for a disinfectant efficacy test at subzero temperatures, this study examined mixtures of frozen foot-and-mouth disease virus or avian influenza virus solutions and disinfectant diluents at $-5^{\circ}C$ and monitored temperature and freezing status of an anti-freezing diluent (AFD, 15% ethanol + 30% propylene glycol + 55% distilled water) over time at various subzero temperatures. Viral solutions and disinfectant diluents froze before the mixtures reached $-5^{\circ}C$, whereas the AFD was not frozen at $-30^{\circ}C$. The times taken for the AFD to reach -10, -20, -30, and $-40^{\circ}C$ from room temperature were 36, 39, 45, and 48 min, respectively.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.91-97
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• 2001

These Study are for the development of the reliability assessment test code and test equipment and test procedures of the heavy sluice gate hydraulic cylinder. Because there is no reliability test code for the heavy sluice gate hydraulic cylinder inside and outside of the country, the modified reliability test code is made reference for the related existing standards like as ISO, JIS, MIL, TUV, DIN, KS and etc. In this study, the novel method is proposed to evaluate efficiency of the heavy sluice gate hydraulic cylinder on the loading conditions and established the conditions of the acceleration life test to reduce the testing time and cycles. The testing equipments for life test, lode operating test, high and low temperature test and salt spray test have been established for 8 month, and the reliability tests are accomplished. The test results of the heavy sluice gate hydraulic cylinder which is produced and tested initially in Korea are satisfied the durability life cycle on the using conditions.

• 한국의류산업학회지
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• 제2권5호
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• pp.416-422
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• 2000

In this study, to find out the physiological reaction of the human body and the sensation of comfort when people are wearing sportswear which is made of waterproof breathable fabrics under general environmental conditions (temperature : $20{\pm}1^{\circ}C$, humidity : $60{\pm}5%RH$, air current : 0.1 m/sec) and rainy environmental conditions (temperature : $20{\pm}1^{\circ}C$, humidity : $60{\pm}5%RH$, air current : 0.1 m/sec, rainfall : 250 1/hr), we made an experiment with sportswear in an artificial climate chamber and studied the thermal physiological response and subjective sensation. Mean skin temperature of the subjects was low and had a big range of fluctuation in rainy environmental conditions of two condition. Temperature started to increase at the beginning of the exercise, reached the maximum at the 2nd level of the exercise and then started to decline. Rectal temperature showed a slighter increase and bigger range of fluctuation in general conditions than in rainy conditions. Except clothing micro climate in rainy conditions, temperature and humidity and their range of fluctuation around back were higher than those around chest. Humidity was high and had wide range of fluctuation in general conditions. Heart rate was 4.4 beats/min higher in general conditions. In subjective test on rainy conditions, the feeling of discomfort increased due to the raindrops fallen on the skin. Unlike that in general conditions, cold sensation increased and humidity sensation reached to the peak after the exercise. In wearing sportswear made of shape memory breathable waterproof fabric, controlling function over a small amount of heat and water was distinctive while it turned out to be not so comfortable over a large amount of heat and water. Through this, the limitation of shape memory breathable waterproof fabric was recognised.