• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.344-348
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• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• Journal of Welding and Joining
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• v.26 no.2
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• pp.43-49
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• 2008

Fatigue cracks due to thermal stratification or corrosion in pipelines of nuclear power plants can cause serious problems on reactor cooling system. Therefore, the development of an integrated technology including fabrication of standard specimens and their practical usage is needed to enhance the reliability of nondestructive testing. The test material was austenitic STS 304, which is used as pipelines in the Reactor Coolant System of a nuclear power plants. The best condition for fabrication of thermal fatigue cracks at the notch plate was selected using the thermal stress analysis of ANSYS. The specimen was installed from the tensile tester and underwent continuos tension loads of 51,000N. Then, after the specimen was heated to $450^{\circ}C$ for 1 minute using HF induction heater, it was cooled to $20^{\circ}C$ in 1 minute using a mixture of dry ice and water. The initial crack was generated at 17,000 cycles, 560 hours later (1cycle/2min.) and the depth of the thermal fatigue crack reached about 40% of the thickness of the specimen at 22,000 cycles. As a results of optical microscope and SEM analysis, it is confirmed that fabricated thermal fatigue cracks have the same characteristics as real fatigue cracks in nuclear power plants. The crack shape and size were identified.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.66-75
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• 2013

In this study, the effect of coating thickness($20{\mu}m$ and $30{\mu}m$) on microstructure and tensile properties in Yb:YAG disk laser welds of Al-Si-coated boron steel (1.2mmt) was investigated. In the case of as welds, the quantity of ferrite was found to be higher in base metal than that in HAZ (Heat Affected Zone) and fusion zone, indicating, fracture occurrs in base metal, and the fracture position is unrelated to the coating thickness. Furthermore, yield strength, tensile strength of base metal and welded specimens showed similar behavior whereas elongation was decreased. On the other hand, base metal and HAZ showed existence of martensite after heat treatment, the fusion zone indicated the presence of full ferrite or austenite and ferrite during heat treatment ($900^{\circ}C$, 5min), After water cooling, austenite was transformed to martensite, and the quantity of ferrite in fusion zone was higher as compared with in base metal, resulting in sharply decrease of yield strength, tensile strength and elongation, which leads to fracture occured at fusion zone. In particular, results showed that because the concentration of Al was higher in 30um coating layer specimen than that of 20um coating specimen, after heat treatment, producing a higher quantity of ferrite was higher after heat treatment in the fusion zone; howevers, it leads to a lower tensile property.

• Journal of Internet Computing and Services
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• v.9 no.6
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• pp.117-125
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• 2008

With increase of concern about the Ubiquitous application, the necessity of the computer system which is miniaturized is becoming larger. The ARM processor is showing a high share from embedded system market. In this paper, ideal method for RTD-1000 controller construction and development is described using ARM microcontroller. Existing RTD-1000 measures distance of disconnection or defect of sensing casket by measuring receiving reflected wave which was sent via copper wire inside the leaking sensing rod. Using this RTD-1000, leakage and breakage of water and oil pipe can be sensed and it reports damage results to the networks. But, existing RTD-1000 wastes hardware resources much and costs a great deal to installation. Also, it needs a cooling device because the heating problem, and has some problem of the secondary memory unit such as the hard disk. So, long tenn maintenance has some problems in the outside install place. In this paper, for the resolving the problem of RTD-1000, RTD-1000A embedded system based on ARM is proposed and simulated.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.570-574
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• 2010

The main function of conventional insulation materials is only to block the heat transfer and reduce heat loss from the building. On the other hand, thermal storage materials can work as an energy saver by absorbing or emitting heat within a specific temperature range. Thermal storage materials for building can maintain a constant temperature by effectively regulating the cycle of indoor temperature. As a result, we can enhance the performance of a cooling and heating system efficiently. In this study, phase change materials (PCMs) were added as thermal storage materials into gypsum boards which are extensively used for building material and we found out the thermal environmental characteristics. In addition, we checked out some problems when applying the thermal storage materials to buildings. Finally, This study set out to examine the degree of environmental-friendly characteristics of thermal storage building materials by analyzing the amount of TVOC and HCHO contents with the possibility of pollutants emission.

• Journal of Embryo Transfer
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• v.16 no.2
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• pp.133-138
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• 2001

The aim of this study was to identify the method on extended canine semen exposed to freezing as assessed by motility, survival and acrosomal changes following different freezing ramp rates. Five ejaculates collected by digital manipulation twice weekly from three dogs (Shih-Tzu) were added Tris-Egg Yolk (TE) buffer and divided into 4 aliquots according to formulation of our laboratory. After cooling to 4$^{\circ}C$ by ramp rate of 0.6$^{\circ}C$/min, the samples frozen by ramp rates of 1.6$^{\circ}C$/min to -$25^{\circ}C$, 3$^{\circ}C$/min to -35$^{\circ}C$, 8.9$^{\circ}C$/min to -7$0^{\circ}C$ and 19$^{\circ}C$/min to -11$0^{\circ}C$, respectively, and then stored in L$N_2$for 2days. Each sample was evaluated on their motility, survivability and acrosome integrity at different thawing temperature. The ramp rate of 3$^{\circ}C$/min to -35$^{\circ}C$/h for freezing and thawing temperature of 37$^{\circ}C$ obtained the highest results to improve survivability, motile spermatozoa and intact acrosome appearance than other onditions. In conclusion, we may suggest freezing semen for canine artificial insemination is more efficient with freezing at a ramp rate of -3$^{\circ}C$/min to -35$^{\circ}C$ and thawing with a water bath adjusted to 37$^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.57-64
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• 2001

The high speed in the wire-drawing process to meet the demands for the increased productivity has a great effect on the heat generated due to plastic deformation and friction between the wire and the drawing dies. During the high carbon steel wire drawing process, the temperature rise gives a great influence to the fracture of wire. In this paper, to control the temperature rise in the wire after the deformation through the drawing die, the calculation method of the wire temperature, which includes the temperature rise in the deformation zone as well as the temperature drop in the block considering the heat transfer among the wire, cooling water and surrounding air, is proposed. These calculated results of the wire temperature at the inlet and exit of the drawing die at each pass are compared with the measured wire temperatures and verified its efficiency. So, using the program to predict the wire temperature, the isothermal pass schedule program was developed. By applying this isothermal pass schedule program to the conventional process condition, a new isothermal pass schedule is redesigned through all passes. As a result, the possibility of wire fracture could be considerably reduced and the productivity of final product could be more increased than before.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.106-112
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• 1989

To investigate varietal differences of anther size, pollen shape, pollen fertility and other agronomic characters under low temperature condition. twenty rice varieties (5 Tongil and 15 Japonica type) were treated at 19$^{\circ}C$ water temperature from booting to heading stage. There was varietal difference of low temperature response which was indicated by the delayed heading, the shortening of culm and panicle length. and the decrease of grain fertility and yield potential resulted from cooling treatment at booting stage. The varieties with low fertility damaged by the low temperature treatment at booting stage showed low pollen density per anther. small or abnormal anthers and pollen, and many sterile pollens. Anther length was correlated significantly with the number of pollens per anther and pollen fertility.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.1
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• pp.20-30
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• 1982

Recent diesel engine has achieved high speed running comparable to that of gasoline engine as a speed improvement effort. Consequently, torsional vibration of high-speed diesel engine induced vibration nosise, reduced horsepower and the like. Viscous damper which is thought to be effective in curtailing the torsional vibration was studied over a wide range of speed. In this investigation, a water cooling, 4-cycle high-speed diesel engine(Msx. 3500 rpm)was used for the study. Theoretical analysis was made by assuming the engine to be an ideal equivalent system(length, moment of inertia) i. e. the multi-degree of freedom equivalent torsional vibration system with damper was analyzed. In the analysis, the inertia moment of suitable damper for this experiment was calculated by varying the relative damping coefficient of damper of engine for each damper. Furthermore, in the torsional vibration experiment, the torsional vibration amplitude of the crankshaft system was measured when the engine was equipped with dampers of different moments of inertia and also when the engine was equipped without dampers. The experimental results were compared with the analytical values and were found to be satisfied. The results of this investigation are summarized below; (1) It was found that for the engine equipped with dampers, the torsional vibration amplitude was reduced to about one third of those without dampers. (2) The optimum value of inertia moment of viscous damper for the engine was found to be about Id=1.05(kg.cm.s$^{2}$) (3) The optimum damping coefficient and the ratio of moment of inertia for the engine were found to be about Ca= 850(kg.cm.s), Rd=0.509, respectively (b1 dapmper).

• Applied Microscopy
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• v.42 no.2
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• pp.111-114
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• 2012

The scanning electron microscopy is an ideal technique for examining plant surface at high resolution. Most hydrate samples, however, must be fix and dehydrate for observation in the scanning electron microscope. Because the microscopes operate under high vacuum, most specimens, especially biological samples, cannot withstand water removal by the vacuum system without morphological distortion. Cryo-techniques can observe in their original morphology and structure without various artifacts from conventional sample preparation. Rapid cooling is the method of choice for preparing plant samples for scanning electron microscopy in a defined physiological state. As one of cryo-technique, high-pressure freezing allows for fixation of native non-pretreated samples up to $200{\mu}M$ thick and 2 mm wide with minimal or no ice crystal damage for the freezing procedure. In this study, we could design to optimize structural preservation and imaging by comparing cryo-SEM and convention SEM preparation, and observe a fine, well preserved Arabidopsis stem's inner ultrastructure using HPF and cryo-SEM. These results would suggest a useful method of cryo-preparation and cryo-SEM for plant tissues, especially intratubule and vacuole rich structure.