• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.140-140
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• 2009

The Metal-ferroelectric-semiconductor (MFS) structure has superior advantages such as high density integration and non-destructive read-out operation. However, to obtain the desired electrical characteristics of an MFS structure is difficult because of interfacial reactions between ferroelectric thin film and Si substrate. As an alternative solution, the MFS structure with buffer insulating layer, i.e. metal-ferroelectric-insulator-semiconductor (MFIS), has been proposed to improve the interfacial properties. Insulators investigated as a buffer insulator in a MFIS structure, include $Ta_2O_5$, $HfO_2$, and $ZrO_2$ which are mainly high-k dielectrics. In this study, we prepared the Dy-doped $La_2O_3$ solution buffer layer as an insulator. To form a Dy-doped $La_2O_3$ buffer layer, the solution was spin-coated on p-type Si(100) wafer. The coated Dy-doped $La_2O_3$ films were annealed at various temperatures by rapid thermal annealing (RTA). To evaluate electrical properties, Au electrodes were thermally evaporated onto the surface of the samples. Finally, we observed the surface morphology and crystallization quality of the Dy-doped $La_2O_3$ on Si using atomic force microscopy (AFM) and x-ray diffractometer (XRD), respectively. To evaluate electrical properties, the capacitance-voltage (C-V) and current density-voltage (J-V) characteristics of Au/Dy-doped La2O3/Si structure were measured.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1185-1191
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• 2008

The core design technology for the multi-effect desalination plant using the thermo compressor (MED-TVC) was investigated by the performance test of multi effect desalination plant in this paper. The final G.O.R (gain of output ratio) of MED-TVC type desalination plant is strongly affected by the performance of thermo-vapor compressor. The present experiments for the desalinating capacity and G.O.R were obtained for the range of the motive steam pressure, 266.0, 250.0, 230.0 and 200.0 kPa. And as a practical problem, to investigate the influence of the sea water temperature to the G.O.R, the inlet steam temperature of the suction water vapor was changed in the range of $311.2{\sim}324.2$ K in the present experiment. Through the experiments, the maximum value of G.O.R was 8.5 at the condition of the motive steam pressure, 136.0 kPa and the minimum value of G.O.R was 8.1 at the condition of the motive steam pressure, 266.0 kPa. And it was confirmed that the range of desalination capacity was $355.2{\sim}264.0$ ton/day in the normal operation condition.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.6-12
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• 1998

Thin film SOI(Silicon-on-insulator) device offer unique advantages such as reduction in short channel effects, improvement of subthreshold slope, higher mobility, latch-up free nature, and so on. But these devices exhibit floating-body effet such as current kink which inhibits the proper device operation. In this paper, the SOI NMOSFET with a T-type gate structure is proposed to solve the above problem. To simulate the proposed device with TSUPREM-4, the part of gate oxide was considered to be 30nm thicker than the normal gate oxide. The I-V characteristics were simulated with 2D MEDICI. Since part of gate oxide has different oxide thickness, the gate electric field strength is not same throughout the gate and hence the impact ionization current is reduced. The current kink effect will be reduced as the impact ionization current drop. The reduction of current kink effect for the proposed device structure were shown using MEDICI by the simulation of impact ionization current, I-V characteristics, and hole current distribution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1108-1115
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• 2004

A new type of a Rotman lens is presented in this paper fur millimeter-wave applications, such as collision avoidance radar. A dielectric slab Rotman lens is proposed to reduce the conductor loss and to create an appropriate farm for favorable implementation at millimeter-wave frequency. The proposed lens consists of a dielectric slab and slot lines whereas the conventional lenses are constructed with parallel conducting plates. The dielectric slab Rotman lens excited in TE$\_$0/ mode shows a high degree of confinement for the fields, low dispersion, and has an appropriate feed structure. A prototype lens has been designed and fabricated with 9 beam ports and 9 array ports together with 9 tapered slot antennas. This lens has been tested in the range from 10 GHz to 15 GHz and the measured beam widths are about 15$^{\circ}$ at 13 GHz. The measurements also show low mutual coupling between beam ports and an efficiency of about 34.6 %. The overall performance is comparable to that of conventional Rotman lenses even though the prototype was tested at lower than desired frequencies in the microwave frequency range due to our limited resources for fabrications and measurements. It is expected that at millimeter-wave frequency the dielectric slab Rotman lens will have lower conductor loss and lower mutual coupling than conventional Rotman lenses.an lenses.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.9-18
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• 2014

PURPOSES : The objective of this study is to evaluate the applicability of the pitch, which is produced during SDA petroleum upgrading process, as a pavement paving material. In order for the purpose, the physical and chemical properties of the pitch are analyzed, and then the various plasticizers are applied in the pitch. METHODS : Two types of pitch are selected from oil refinery companies, which are owned the SDA petroleum upgrading process. Also, two types of asphalt binders, PG 64-22 and PG 58-22, are employed to compare with the pitch because these two types of asphalt binders are currently used as paving materials. For the chemical property of the pitch, the composition of SARA (Saturate, Aromatic, Resin, Asphaltene), the elementary composition, and the functional group are analyzed. For the physical property of the pitch, the basic material property tests, such as penetration test, softening point test, flash point test, ductility test, and rotational viscometer test, are performed. Also, the DSR (Dynamic Shear Rheometer) test and the BBR (Bending Beam Rheometer) test are conducted using asphalt binder specimens obtained by both short term aging (Rolling Thin Film Oven, RTFO) and long term aging (Pressure Aging Vessel, PAV) processes. The rheological property of each pitch type is evaluated as a function of temperatures and loading cycles. PG 64-22 asphalt binder is used as a control material. RESULTS AND CONCLUSIONS : The Pitch may not be suitable for the pavement paving material without modifications, but the pitch can be used as alternatives of modified addictive or asphalt. If low molecular component, such as saturate and aromatic components, are added in the pitch based on the development of various plasticizers, it has a strong possibility for the pitch to be used as a alternative. However, in order to verify the performance property of the pitch, further research is needed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.475-475
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• 2013

Cuprous oxide ($Cu_2O$)는 밴드갭이 2.17 eV p-type 산화물 반도체로써 태양에너지 변환기, photocatalysis (광촉매작용), 센서, 스위칭 메모리 등 응용이 다양한 재료이다. 산화물 반도체의 기본 특성은 나노/마이크로 범위 안에서 재료의 표면형태, 크기, 구조와 형상 공간방향등에 크게 영향을 받는다. 그렇기 때문에 원하는 $Cu_2O$ 특성을 얻기 위해서 성장 거동을 아는 것은 매우 중요하다. RF 마그네트론 스퍼터법으로 rod 성장 사례는 잘 알려지지 않았다. 그래서 RF 마그네트론 스퍼터법 $Cu_2O$ rod 형성 실험을 통하여 $Cu_2O$ 형성과 성장 거동을 알아보았다. RF 마그네트론 스퍼터법으로 $Cu_2O$ rod를 glass 기판 위에 Cu metal target을 이용하여 형성시켰다. $Cu_2O$ rod 합성을 위해 기판온도 및 산소분압 O2/(Ar+O2)=3%, 5%, 7% 증착시간 등을 변화시켜 실험하였다. 성장된 rod의 분석은 XRD, SEM으로 확인하였다. 성장 거동은 증착온도와 증착시간에 차이를 보였다. 증착온도 $550^{\circ}C$에서 rod가 생성되는 것을 관찰하였다. 증착시간이 길어질수록 rod 길이가 길어지고 일정 시간이 지나면 rod의 길이 성장보다는 두께(폭)가 성장하는 것을 확인하였다. 증착온도 $550^{\circ}C$ 그리고 산소분압 3%, 5%, 7% 조건에서 rod 합성 실험을 하였을 때 3%, 5% 조건에서 rod의 성장을 확인하였다. 이때 3%, 5% 산소분압에 따라 rod의 모양이 변화하였다. 하지만 7% 조건에서는 rod가 성장하지 않았다. 이유는 3%, 5%에서는 Cu metal peak을 확인하였지만, 7% 조건에서는 Cu metal peak이 없었다. 이로부터 Cu metal이 $Cu_2O$ rod 생성에 영향을 미치는 중요한 요소임을 예상할 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.207-212
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• 2013

A novel pixel circuit that uses only n-type low-temperature polycrystalline silicon (poly-Si) thin-film transistors (LTPS-TFTs) to compensate the threshold voltage variation of a OLED driving TFT is proposed. The proposed 6T1C pixel circuit consists of 5 switching TFTs, 1 OLED driving TFT and 1 capacitor. When the threshold voltage of driving TFT varies by ${\pm}0.33$ V, Smartspice simulation results show that the maximum error rate of OLED current is 7.05 % and the error rate of anode voltage of OLED is 0.07 % at Vdata = 5.75 V. Thus, the proposed 6T1C pixel circuit can realize uniform output current with high immunity to the threshold voltage variation of poly-Si TFT.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.12
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• pp.89-100
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• 1997

This paper investigated a new type of low voltage threshold switch (LVTS). As distinguished from the many other types of electronic threshold switches, the LvTS is ; voltage controlled, occurs at low voltages ($V_{2}$ $O_{5}$lV devices. The average low threshold voltage < $V_{LVT}$>=218 mV (standard deviation =24mV~kT/q, where T=300K), and was independent of the device area (x100) and amorphous oxide occurred in an ~22.angs. thick interphase of the V/amorphous- $V_{2}$ $O_{5}$ contacts. At $V_{LVT}$ there was a transition from an initially low conductance (OFF) state into a succession of quantized states of higher conductance (ON). The OFF state was spatically homogeneous and dominated by tunneling into the interphase. The ON state conductances were consistent with the quantized conductances of ballistic transport through a one dimensional, quantum point contact. The temeprature dependence of $V_{LVT}$, and fit of the material parameters (dielectric function, barrier energy, conductivity) to the data, showed that transport in the OFF and ON states occurred in an interphase with the characteristics of, respectively, semiconducting and metallic V $O_{2}$. The experimental results suggest that the LVTS is likely to be observed in interphases produced by a critical event associated with an inelastic transfer of energy.rgy.y.rgy.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.41-47
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• 2010

The effects of thermal treatment on CNTs, which were coated with a-$CN_x$ thin film, were investigated and related to variations of chemical bonding and morphologies of CNTs and also properties of field emission induced by thermal treatment. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition (ICP-CVD) system, and a-$CN_x$ films were coated on the CNTs using an RF magnetron sputtering system. Thermal treatment on a-$CN_x$ coated CNT-emitters was performed using a rapid thermal annealing (RTA) system by varying temperature ($300-700^{\circ}C$). Morphologies and microstructures of a-$CN_x$/CNTs hetero-structured emitters were analyzed by FESEM and HRTEM. Chemical composition and atomic bonding structures were analyzed by EDX, Raman spectroscopy, and XPS. The field emission properties of the a-$CN_x$/CNTs hetero-structured emitters were measured using a high vacuum (below $10^{-7}$ Torr) field-emission measurement system. For characterization of emission stability, the fluctuation and degradation of the emission current were monitored in terms of operation time. The results were compared with a-$CN_x$ coated CNT-emitters that were not thermally heated as well as with the conventional non-coated CNT-emitters.

• Transactions of Materials Processing
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• v.14 no.3 s.75
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• pp.282-290
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• 2005

Nowadays, TFT-LCD is widely used as display unit of many digital devices. And, the backlight unit(BLU) is used as a light source of TFT-LCD module. In the backlight unit, the most important component is a light guide, which guides the input light to the TFT-LCD module uniformly. Recently, many researchers have focused on improving the efficiency of BLU by changing the design and structure of a light guide. In the present paper, a series of simulation was performed to find the optimal luminance distribution of emanated light from the given geometry as the first step. From the results of simulations for the light guide with given V-groove pattern, the emanated light from it is mostly affected by the groove angle. In the case of acute angle, about 74 degrees was found as optimal angle to satisfy the restrictions of angular luminance distribution, FWHM, the maximum luminance, etc. However, as far as the average luminance value was concerned, the case of 120 degrees(abtuse angle) was found to be the best while prism films were added to the BLU. As a next step the light guide samples of 74 and 120 degrees were manufactured by DSF method, which was recently proposed by the authors. Of course, most of design parameters were chosen by the aid of simulation results. Finally, the results of average luminance values were compared between the simulation and DSF molded samples.