• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.347-352
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• 2000

We have stabIhzed the laser frequency of a commercial dIode laser using a ULE (Ultra-low expansion material) reference cavIty and the cunent modulation charactenstics of the dIode itself The liuewIdth of the frce running laser was about a 1 MHz (rms) for a sampling time of 1 s and the drift rate was 300 kHz/s. Vvhen the laser is locked to oue sIde of the transmission signal from the ULE reference cavity, the lincwidth was reduced to 46 kHz (nus) for a sampling time longer than 10 ms. The root Allan variance was less than 2 kHz for a sampling time langeI than10 ms. 10 ms.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.212-216
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• 2000

ZnO varistors for distribution surge arrester (18kV, 5kA) were developed and tested microstructure and electrical characteristics. Microstructure of ZnO varistor was consisted of ZnO grain, spinel phase and Bi-rich phase. Average grain size of ZnO varistor was $\mu\textrm{m}$ Reference voltage and lightning impulse residual voltage of ZnO varistor exhibited a good haracteristics above 5.5kV and below 11.56kV, respectively. Consequently, discharge capacity which is the most important characteristics of ZnO varistor for surge arrester exhibited excellent properties above 70kA at twice high-current impulse test. Moreover, variation rate of reference voltage and lightning impulse residual voltage showed below 5% and 2% after high-current impulse test, respectively. Leakage current and watt loss of ZnO varistor will not increase during accelerated aging test at stress condition, such as 3.213kV/$115^{\circ}C$/1000h.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.579-580
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• 2014

In this research, modeling and analysis of an ultrasonic transducer composed of single crystal piezoelectric material(PMN-28PT) are conducted with FEM in reference with that composed of piezoelectric ceramic(PZT-4). Acoustic performances of the ultrasonic transducer are compared with magnitude, phase of impedance and trasmitting voltage response according to the type of piezoelectric materials.

• Journal of Korean Library and Information Science Society
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• v.36 no.4
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• pp.349-364
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• 2005

The main Points of the 7th Education Program are: taking a serious view of development of children's individuality and creativity, and encouragement students their accord activity with applying digital reference for teaching and learning. It Is the suggestion of revitalization method of digital material room, afterward. by means of analyzation for satisfaction and demand and using status of children's library digital material room along with emphasis of self-loading learning and boosting self-solving ability based on computer and IT paradigm. The purpose is : providing foundation of active Information service and suggestion of revitalization method by means of analyzing operation and effective using children's library digital material room at Nowon Children's Library opened 2nd February, 2003. In 2nd chapter; thesis of conceptive model of children's library digital material room. In 3rd Chapter: Present status analysis of N. W. Children's library digital material room operation, and analysis of using and demand of public school 100 pupils. In 4th Chapter : Suggesting conclusion of revitalization of children's library digital material room based on utilization and demand appeared through this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.7-8
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• 2009

In the presence of infrared light, a CMOS Readout IC (ROIC) for a microbolometer typed infrared sensor detects the voltage or current that is caused by the changing in resistance in the bolometer sensor. A serious problem in designing the ROIC is how the value of the bolometer and reference resistors vary because of variations in manufacturing process. Since different pixel have different, resistance values, sensor operations must contend with fixed pattern noise (FPN) problems. In this paper, we propose a novel technique to compensate for the fluctuation in reference resistance by tiling into account the process variation. By using constant current source basing and correlated double sampling, we solved FPN.

• Ocean and Polar Research
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• v.37 no.3
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• pp.225-233
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• 2015

To understand the fluctuation of global carbon levels caused by the biogeochemical cycle within the ocean interior, it is essential to achieve comparability of global oceanic nutrient data to a fairly high degree. The Scientific Committee on Ocean Research (SCOR) commissioned a working group (WG147) to establish a system for achieving comparability of oceanic nutrient data within 1% among laboratories around the world. The introduction of international activities for improving nutrient comparability will facilitate the use of nutrient reference material of seawater by researchers within Korea, which will help in meeting international standards of nutrient comparability and promote international cooperation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.699-702
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• 2002

A DC current sensor is disclosed in which two pairs of saturable cores are provided so as enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. Circuit for detection of an asymmetry in the magnetization current, generated by a reference alternating voltage, in a signal-conditioner. The reference alternating voltage is fed to the respective series circuits such that no resultant induction current is induced in the modulating current. The voltages over the resistor form input signals for two peak value detectors, the strength of the output signal of which represents the degree of asymmetry of magnetization current. This paper describes the development a DC current sensor and its signal-conditioner.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.744-746
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• 2003

A ZnO varistor with reference voltage 250V/mm was fabricated through the control of particle size in slurry and the variation of sintering conditions. It was found that to measure the flatness of the V-I characteristic curve in the small-current region and the flatness of the V-I characteristic curve in a large-current region was improved nonlinearity of the fabricated ZnO varistor. According to the IEC 60099-4 was measured the accelerated aging test and high current test of the distribution class surge varistor which is excellent in respect to the property of ZnO varistor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.926-929
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• 2003

The dissolved oxygen sensor of thick film type was fabricated by screen print method and measured the characteristic, reference electrode used Ag/AgCl, and working electrode used Pt. The devices are continuously powered at potential of $0.7V{\sim}0.8V$ versus Ag/AgCl reference electrode and results indicated that the response characteristic of sensor was $1.002{\mu}A{\sim}19.792{\mu}A$ for thirty seconds. we can know that it is good linearity when compared with of existent dissolved oxygen meter. Therefore sensor fabricated excels sensitivity for dissolved oxygen and will be considered to be applied typically because the price is costly.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.367-367
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• 2011

CIGS solar cell with copper, indium, gallium and selenium is a second generation solar cells for the lowering of the manufacturing cost. The relative ratio of the four elements is one of the most important measurement issues because the photovoltaic property of CIGS solar cell depends on the crystalline structure of the CIGS layer. However, there is no useful analysis method for the composition of the CIGS layer. Recently, AES depth profiling analysis of CIGS films has been studied with a reference material certified by inductively coupled plasma optical emission spectroscopy. However, there are some problems in AES depth profiling analysis of CIGS films. In this study, the in-depth profiling analysis was investigated by secondary ion mass spectrometry (SIMS) depth profiling analysis. We will present the compositional depth profiling of CIGS films by SIMS and its applications for the development of CIGS solar cells with high efficiency.