• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1448-1452
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• 2004

In this paper, a photodiode capable of obtaining a sufficient photo/ dark current ratio at both a forward bias state and a reverse bias state is proposed. The photodiode includes a glass substrate, an Cr thin film formed as a lower electrode over the glass substrate, Cr silicide thin film(∼l00$\AA$) ) formed as a schottky barrier over the Cr thin film, a hydrogenated amorphous silicon film formed as a photo conduction layer over a portion of the Cr silicide thin film. Transparent conduction film ITO (thickness 100nm) formed as an upper electrode over the hydro-generated amorphous silicon film is then deposited in pure argon at room temperature for the Schottky contact and light window. The high quality Cr silicide thin film using annealing of Cr and a-Si:H is formed and analyzed by experiment. We have obtained the film with a superior characteristics. The dark current of the ITO/a-Si:H Schottky at a reverse bias of -5V is ∼3$\times$IO-12 A/un2, and one of the lowest reported, hitherto. AES(Auger Electron Spectroscophy) measurements indicate that this notable improvement in device characteristics stems from reduced diffusion of oxygen, rather than indium, from the ITO into the a-Si:H layer, thus, preserving the integrity of the Schottky interface. The spectral response of the photodiode for wavelengths in the range from 400nm to 800nm shows the expected behavior whereby the photocurrent is governed by the absorption characteristics of a-Si:H.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.133-133
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• 2008

Recently, as the down-scailing of field-effect transistor devices continues, Schottky-barrier field-effect transistors (SB-FETs) have attracted much attention as an alternative to conventional MOSFETs. SB-FETs have advantages over conventional devices, such as low parasitic source/drain resistance due to their metallic characteristics, low temperature processing for source/drain formation and physical scalability to the sub-10nm regime. The good scalability of SB-FETs is due to their metallic characteristics of source/drain, which leads to the low resistance and the atomically abrupt junctions at metal (silicide)-silicon interface. Nevertheless, some reports show that SB-FETs suffer from short channel effect (SCE) that would cause severe problems in the sub 20nm regime.[Ouyang et al. IEEE Trans. Electron Devices 53, 8, 1732 (2007)] Because source/drain barriers induce a depletion region, it is possible that the barriers are overlapped in short channel SB-FETs. In order to analyze the SCE of SB-FETs, we carried out systematic studies on the Schottky barrier overlapping in short channel SB-FETs using a SILVACO ATLAS numerical simulator. We have investigated the variation of surface channel band profiles depending on the doping, barrier height and the effective channel length using 2D simulation. Because the source/drain depletion regions start to be overlapped each other in the condition of the $L_{ch}$~80nm with $N_D{\sim}1\times10^{18}cm^{-3}$ and $\phi_{Bn}$ $\approx$ 0.6eV, the band profile varies as the decrease of effective channel length $L_{ch}$. With the $L_{ch}$~80nm as a starting point, the built-in potential of source/drain schottky contacts gradually decreases as the decrease of $L_{ch}$, then the conduction and valence band edges are consequently flattened at $L_{ch}$~5nm. These results may allow us to understand the performance related interdependent parameters in nanoscale SB-FETs such as channel length, the barrier height and channel doping.

• The KIPS Transactions:PartD
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• v.15D no.6
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• pp.861-872
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• 2008

As rapid development of computing environment, field of automatic identification research which interoperates with various physical objects and digital information is making active progress. Although the automatic identification system is widely used in various industries, application of automatic identification system in the field of medical health doesn't reach other industry. Therefore research in medical health supplies such as medical equipment, blood, human tissues and etc is on progress. This paper suggests the application of automatic identification technology for biological resources which is core research material in human genome research. First of all, user environment requirements for the introduction of automatic identification technology are defined and through the experiments and research, barcode is selected as a suitable tag interface. Data Matrix which is 2D barcode symbology is chosen and data schema is designed based on UCC/EAN-128 for international defecto standard. To showapplicability of proposed method when applied to actual environment, we developed, tested and evaluated application as following methods. Experiments of barcode read time at 196 and 75 below zero which is actual temperature where biological resources are preserved resulted read speed of average of 1.6 second and the data schema satisfies requirements for the biological resources application. Therefore suggested method can provide data reliability as well as rapid input of data in biological resources information processing.

• Elastomers and Composites
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• v.36 no.2
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• pp.111-120
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• 2001

Mechanical properties and their adhesion behavior with zinc- and brass-plated steel cords of natural rubber/acrylonitrile-butadiene blend compounds were investigated as a function of blend ratio. The Mooney viscosity and stress relaxation time were found to be lowered with increasing NBR content. Tensile modulus generally increased with increasing NBR content. Tensile stress at break stayed constant up to about 40 phr and showed minimum at $50{\sim}60 phr$, and thereafter increased with increasing NBR content. Strain at break decreased linearly below 50 phr, and above the level it showed nearly constant value. Based on the abrupt drops in elastic modulus and tan ${\delta}$ peak, the glass transition temperature of NR and NBR were found to be -55 and $-10^{\circ}C$, respectively. In the case of NR/NBR blend compounds, two distinct transition points were observed and each transition position was not affected by NBR level indicating an incompatible nature of NR/NBR blend system. The pullout force and rubber coverage decreased to the level of about 40% to that of pure m compound, when the 50 phr of NR was replaced by NBR. However, the pure NBR compound showed the comparable adhesion performance with NR(${\sim}90%$). The sulfur concentration was found to become lower with the increased NBR content at the adhesion interface based on the Auger spectrometer results, representing a lack of adhesion layer formation, and this was explained for a possible cause of low adhesion performance with adding NBR.

• Journal of the Korean Chemical Society
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• v.39 no.11
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• pp.869-877
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• 1995

Carbonation process of Jung sun slake lime$(Sr(OH)_2=0.053 wt%)$ suspension with $CO_2$ gas at 30∼80$^{\circ}C$ has been studied to investigate the formation process of aragonite. The reaction temperature at above $50^{\circ}C$, rhombic nuclei of $SrCO_3$ has been grown with the interaction of $CO_3^{2-}$(aq) which is profitable to growth the nuclei at the liquid film of gas-liquid interface to form pillar aragonite crystal. At $40^{\circ}C$, the controlling of concentration of $CO_2$(aq) at the beginning of the reaction has been made the nuclei to growth to be an aragonite crystal. Addition of some $Sr(OH)_2$ to Yi Lee slake lime $(Sr(OH)_2=0.011 wt%)$ suspension and controlling the concentration of $OH^-$(aq) and $CO_2$(aq), the carbonation reaction produced pillar aragonite crystal with the short side of 0.1∼0.2 ${\mu}m$ and long side of 1∼2 ${\mu}m.$

• Korean Journal of Food Science and Technology
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• v.10 no.1
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• pp.52-56
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• 1978

The mechanism of cooking rice was investigated using a japonica type rice variety, Akibare, of 50%, 70% and 90% polishing degrees. The hardness of rice cooked at various cooking temperatures ($90^{\circ}-120^{\circ}C$) was measured with a Texturometer. The cooking rate followed the equation of a first-order reaction. The reaction rate constants were in the increasing order of 50%, 70% and 90% polished rice. The temperature coefficient of the reaction rate constant at cooking temperatures of ($90^{\circ}-100^{\circ}C$) was about 2 in all rice samples. The activation energies of cooking at temperatures below $100^{\circ}C$ and above $100^{\circ}C$ were about 17,000 and 9,000 cal/mole, respectively. The polishing degrees and water soaking time of rice did not affect the activation energy of cooking; however, the lower polishing degrees and shorter soaking increased the cooking time The experimental results suggested that the cooking process of rice comprises two mechanisms: At temperatures below $100^{\circ}C$ the cooking rate is controlled by the reaction rate of rice constituents with water, and at temperatures above $100^{\circ}C$, it is controlled by the rate of diffusion of water through the cooked portion (or layer) toward the interface of uncooked core in which the reaction is occurring.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.172-177
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• 2010

This study reports the high-temperature oxidation kinetics, ASR(area specific resistance), and interfacial microstructure of metallic interconnects coated with conductive oxides in oxidation atmosphere at $800^{\circ}C$, The conductive material LSC($La_{0.8}Sr_{0.2}CoO_3$, prepared by Solid State Reaction) was coated on the Crofer22APU. The contact behavior of coating layer/metal substrate was increased by sandblast. The electrical conductivity of the LSC coated Crpfer22APU was measured by a DC two probe four wire method for 4000hr, in air at $800^{\circ}C$. Microstructure and composition of the coated layer interface were investigated by SEM/EDS. These results show that a coated LSC layer prevents the formation and growth of oxide scale such as $Cr_2O_3$ and enhances the long-term stability and electrical performance of metallic interconnects for SOFCs.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.239-246
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• 1999

A highly sensitive photovoltaic infrared photodiode was fabricated for detecting infrared light in $3{\sim}5\;{\mu}m$ wavelength range on InSb wafer with p-i-n structure grown by MOCVD. Silicon dioxide($SiO_2$) insulating films for the junction interface and surface of photodiode were prepared using RPCVD because InSb has low melting point and evaporation temperature. After formation of In ohmic contacts by thermal evaporation, the electrical properties of the photodiode were characterized in dark state at 77K. A product of zero-bias resistance and area($R_0A$) showed $1.56{\times}10^6\;{\Omega}{\cdot}cm^2$ that satisfied BLIP(background limited infrared photodetector) condition. When the photodiode was tested under infrared light, the normalized detectivity of about $10^{11}\;cm{\cdot}Hz^{1/2}{\cdot}W^{-1}$ was obtained. we successfully fabricated a unit cell with InSb IR array with good quantum efficiency and high detectivity.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.407-413
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• 1997

The crystallized CuPc(copper phthalocyanine) film on a p-type <100> Si substrate is prepared at the substrate temperature of $300^{\circ}C$ by thermal evaporation. X -ray diffraction analysis showed the CuPc film to have a-axis oriented structure. For the measurement of photovoltaic characteristics of the CuPc/Si film and the Si substrate, a transverse current-voltage (I-V) curve is observed. In the dark, the Au/Si junction is shown to be ohmic contact. However, under illumination, a photovoltaic effect is not observed. The I-V curve in the dark indicates that the CuPc film on Si may form an ohmic contact. Since the CuPc film is a p-type semiconductor, the CuPc/p-Si junction has no barrier at the interface. Under illumination, the CuPc/Si junction shows a large photocurrent comparing with that of the wafer. The result indicates that the CuPc layer plays an important role in the photocarrier generation under red illumination (600 nm). The CuPc/Si film shows the photo voltaic characteristics with a short-circuit photocurrent ($J_{sc}$) of $4.29\;mA/cm^{2}$ and an open-circuit voltage ($V_{oc}$) of 12 mA.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.315-319
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• 1996

We have developed a prototype patient monitoring system including module-based bedside units, interbed network, and central stations. A bedside unit consists of a color monitor and a main CPU unit with peripherals including a module controller. It can also include up to 3 module cases and 21 different modules. In addition to the 3-channel recorder module, six different physiological parameters of ECG, respiration, invasive blood pressure, noninvasive blood pressure, body temperature, and arterial pulse oximetry with plethysmogaph are provided as parameter modules. Modules and a module controller communicate with up to 1Mbps data rate through an intrabed network based on RS-485 and HDLC protocol. Bedside units can display up to 12 channels of waveforms with any related numeric informations simultaneously. At the same time, it communicates with other bedside units and central stations through interbed network based on 10Mbps Ethernet and TCP/IP protocol. Software far bedside units and central stations fully utilizes gaphical user interface techniques and all functions are controlled by a rotate/push button on bedside unit and a mouse on central station. The entire system satisfies the requirements of AAMI and ANSI standards in terms of electrical safety and performances. In order to accommodate more advanced data management capabilities such as 24-hour full disclosure, we are developing a relational database server dedicated to the patient monitoring system. We are also developing a clinical workstation with which physicians can review and examine the data from patients through various kinds of computer networks far diagnosis and report generation. Portable bedside units with LCD display and wired or wireless data communication capability will be developed in the near future. New parameter modules including cardiac output, capnograph, and other gas analysis functions will be added.