• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.128-134
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• 1995

A fiber-optic temperature sensor utilizing an optical absorption device (InP) was fabricated. The spectrum of transmitted light through an InP device was obtained at the three temperatures(249 K, 369 K). A stabilized LED(light emmiting diode) driver, photoreceiver, and signal proocessing electronics were designed. An intensity referencing technique was adopted in order to minimize the fluctuation of output signal due to external pertubation of the transmitting optical fiber. The optical absorption edge of the InP device moves to longer wavelength at a rate of 0.42 nm / K, and energy gap of InP is 1.35 eV at room temperature. From these results, it is concluded that the InP device has temperature dynamic range of 300 K with LED of center wavelength of 940nm and spectral width of 50nm. The designed fiber-optic temperature sensor system showed good linearity within the temperature range from -30$^{\circ}C$ to + 150$^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.2
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• pp.182-187
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• 1988

Hot carrier induced device degradation characteristics under DC bias stress have been investigated in n-MOSFETs with channel length of 1.2,1.8 um, and compared with those of LDD structure device with same channel length. Based on these results, the device lifetime in normal operating bias(Vgs=Vds=5V) is evaluated. The lifetimes of conventional and LDD n-MOSFET with channel length of 1.2 um are estimated about for 17 days and for 12 years, respectively. The degradation rate of LDD n-MOSFET under the same stress is the lowest at n-region implnatation dose of 2.5E15 cm-\ulcorner while the substrate current is the lowest at the dose of 1E13cm-\ulcorner Thses results show that the device degradation characteristics are basic measurement parameter to find optimum process conditions in LDD devices and evaluate a reliability of sub-micron device.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.7
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• pp.32-37
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• 1993

A novel insulated gate bipolar transister (IGBT), called insulated trench cathode IGBT (ISTC-IGBT), is proposed. ISTC-IGBT has a trenched well with the shallow P$^{+}$ juction in the conventional IGBT structure. The proposed structure has the capability of effectively suppressing the parasitic thyristor latchup. The holding current of ISTC-IGBT is about 2.2 times greater than that of the conventional IGBT. Detailed analysis of the latchup characteristics of ISTC-IGBT is performed by using the two-dimensional device simulator, PISCES-II B.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.10
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• pp.20-26
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• 1993

The base-collector capacitance of an npn bipolar transistor in bipolar or BiCMOS technology has significant influence on the switching performances, and comprises pnjunction component and MOS component. Both components have complicated dependences on the isolation oxide structure, epitaxial doping density, and bias voltage. Analytical/empirical formulas for both components are derived in this paper for a generic isolation structure as a function of epitaxial doping density and bias voltage based on some theoretical understanding and two-dimensional device simulations. These formulas are useful in estimating the effect of device isoation schemes on the switching speed of bipolar transistors.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.70-76
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• 1994

A humidity sensing device based on a new humidity sensing principle is designed and fabricated in this study. The silicon thermopile is consisted of 25 couples of p-type diffused layer/Al strips. The internal resistance and the Seebeck coefficient are 300kl and 537$\mu$V/K, respectively Fabricated sensors showed linear response characteristics proportional to relative humidity changes with a sensitivity of 9$\mu$V/%RH in the range from 20% to 90%.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.5
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• pp.370-374
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• 1991

A high performance fully ion-implanted InP JFET was characterized for high speed switching elements. The switch has an insertion loss of 5.5dB with 31.6dB isolation at 1GHz. This device can effectively swithc a byte-multiplexed 2Gb/s signal and an eye-diagram taken at 2Gb/s shows an error-free eye pattern. Therefore, this device can be used as a switching element for high transmission data rate for monolithic integration of optoelectronic circuit in the long-wavelength region.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.82-88
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• 1992

This paper presents one of the first comprehensive studies of how hot electron degradation impacts the input offset voltage of a CMOS differential amplifiers. This study utilizes the concept of a virtual source-coupled MOSFET pair in order to evaluate offset voltaged egradation directly from individual device measurement. Next, analytical models are developed to describe the offset voltage degradation. These models are used to examine how hot electron induced offset voltage is affected with the device parameters.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.67-72
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• 1987

InSb TFT is fabricated by the vacuum evaporation method and I-V characteristics are measured. Employing Davidon Fletcher-Powell algorithm, the device parameters are extracted. The current-voltage relations calculated by extracdted parameters are in good agreement with experimental results. It is found that optimization technique may be more simple and accurate than curve fitting method in device parameters extration.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.361-364
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• 2007

A small sized device with computing, communicating, sensing capability is changing our life. It will be deployed in the world and acquire a lot of data from the world. It is used for various applications such as military surveillance, environmental monitoring, structure health monitoring, building management, asset tracking, etc. In this paper we focus on USN middleware for asset tracking. A mobile asset is moving here and there within a specific area. The USN middleware tracks the mobile assets in real-time by using sensor nodes and notify their current positions to a user. To achieve the goal, the USN middleware provides some features related to the positions of mobile assets.. They are storing location data by using 3D indexing method, retrieving them by using spatio-temporal query, making trace of an asset, and retrieving the history data of an asset. In the paper, we developed USN middleware to adapt the requirements of asset tracking. It can help users increase the efficiency of their business related to mobile assets and make a valuable decision.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.19-27
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• 2007

Entering the 21st century, the demand on information service via mobile devices is skyrocketing along with the popularization of computers and mobile communication devices and the rapid development of wireless communication technology. In particular, as mobile device service such as LBS and Telematics becomes highlighted, the management of mobile devices is ever more drawing attention. However, since there is no fixed standard on geographical space data, many commercialized monitoring systems do not use common geographical space data but independent geographic information. Furthermore, as it is impossible to save location information of each mobile device by integrating such information after acquiring them, it is difficult to trace management. Therefore, in this paper, geographic data with DXF. DWG and SHP format, which are commonly used files, were created and visualized by GML format, OGC standard advice. And then, TMS(Trace Monitoring System of Mobile Device) that can trace and manage information after acquiring and saving space information that show the movement of users was implemented.