• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.215.2-215.2
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• 2015

We fabricated dual active layer (DAL) thin film transistors (TFTs) with indium tin zinc oxide (ITZO) and indium gallium zinc oxide (IGZO) thin film layers using solution process. The ITZO and IGZO layer were used as the front and back channel, respectively. In order to investigate the bias stress stability of ITZO SAL (single active layer) and ITZO/IGZO DAL TFT, a gate bias stress of 10 V was applied for 1500 s under the dark condition. The SAL TFT composed of ITZO layer shows a poor positive bias stability of ${\delta}VTH$ of 13.7 V, whereas ${\delta}VTH$ of ITZO/IGZO DAL TFT was very small as 2.6 V. In order to find out the evidence of improved bias stress stability, we calculated the total trap density NT near the channel/gate insulator interface. The calculated NT of DAL and SAL TFT were $4.59{\times}10^{11}$ and $2.03{\times}10^{11}cm^{-2}$, respectively. The reason for improved bias stress stability is due to the reduction of defect sites such as pin-hole and pores in the active layer.

• 멤브레인
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• 제24권5호
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• pp.367-374
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• 2014

본 연구에서는 LSCF/GDC (20 : 80 vol%) 복합 분리막 표면에 LSC/GDC (50 : 50 vol%) 활성층을 코팅한 후 활성층의 열처리 온도, 두께, 침투법을 이용한 STF 도입이 산소투과 특성에 미치는 영향을 고찰하였다. 활성층 도입은 복합 분리막의 산소 투과 유속을 급격히 증진시켰으며 이는 활성층 성분인 LSC/GDC (50 : 50 vol%)가 전자 전도성 및 표면 산소 분해 반응을 증진시켰기 때문이었다. 활성층의 열처리 온도가 $900^{\circ}C$에서 $1000^{\circ}C$로 증가한 경우, 산소 투과 유속은 증가하였고 이는 분리막과 활성층 사이 그리고 활성층의 결정입간 접촉이 증진하여 산소이온과 전자 흐름을 증진시켰기 때문으로 설명되었다. 코팅층의 두께가 약 $10{\mu}m$에서 약 $20{\mu}m$로 증가한 경우, 산소 투과 유속은 오히려 감소하였는데 이는 코팅층의 두께가 증가할수록 기공을 통한 공기 중의 산소 유입이 어려워지기 때문으로 설명되었다. 또한, 코팅층에 침투법을 이용하여 STF를 도입한 경우가 STF를 도입하지 않은 경우 보다 높은 산소 투과 유속을 보였는데 이는 도입된 STF가 산소 분해하는 표면 반응 속도를 촉진시키기 때문이다. 본 연구로부터 LSC/GDC (50 : 50 vol%) 활성층 코팅 및 특성 제어는 LSCF/GDC (20 : 80 vol%) 복합 분리막의 산소투과 증진에 매우 중요함을 확인하였다.

• 대한원격탐사학회지
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• 제33권1호
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• pp.47-60
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• 2017

The permafrost active layer plays an important role in permafrost dynamics. Ecological patterns, processes, and water and ice contents in the active layer are spatially and temporally complex depending on landscape heterogeneity and local-scale variations in hydrological processes. Although there has been emerging interest in the application of optical remote sensing techniques to permafrost environments, optical sensors are significantly limited in accessing information on near surface geo-cryological conditions. The primary objective of this study was to investigate capability of L-band SAR data for monitoring spatio-temporal variability of permafrost ecosystems and underlying soil conditions. This study exploits information from different polarimetric SAR observables in relation to permafrost environmental conditions. Experimental results show that each polarimetric radar observable conveys different information on permafrost environments. In the case of the dual-pol mode, the radar observables consist of two backscattering powers and one correlation coefficient between polarimetric channels. Among them, the dual-pol scattering powers are highly sensitive to freeze/thaw transition and can discriminate grasslands or ponds in thermokarst area from other permafrost ecosystems. However, it is difficult to identify the ground conditions with dual-pol observables. Additional backscattering powers and correlation coefficients obtained from quad-pol mode help understanding seasonal variations ofradar scattering and assessing geo-cryological information on soil layers. In particular, co-pol coherences atHV-basis and circular-basis were found to be very usefultools for mapping and monitoring near surface soil properties.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.211.2-211.2
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• 2015

In order to investigate the effect of front channel in DAL (dual active layer) TFT (thin film transistor), we successfully fabricated DAL TFT composed of ITZO and IGZO as active layer using the solution process. In this structure, ITZO and IGZO active layer were used as front and back channel, respectively. The front channel was changed from 0.05 to 0.2 M at fixed 0.3 M IGZO of back channel. When the mol concentration of front channel was increased, the threshold voltage (VTH) was increased from 2.0 to -11.9 V and off current also was increased from 10-12 to 10-11. This phenomenon is due to increasing the carrier concentration by increasing the volume of the front channel. The saturation mobility of DAL TFT with 0.05, 0.1, and 0.2 M ITZO were 0.45, 4.3, and $0.65cm2/V{\cdot}s$. Even though 0.2 M ITZO has higher carrier concentration than 0.05 and 0.1 M ITZO, the 0.1 M ITZO/0.3 M IGZO DAL TFT has the highest saturation mobility. This is due to channel defect such as pores and pin-holes. These defect sites were created during deposition process by solvent evaporation. Due to these defect sites, the 0.1 M ITZO/0.3 M IGZO DAL TFT shows the higher saturation mobility than that of DAL TFT with front channel of 0.2 M ITZO.

• IEIE Transactions on Smart Processing and Computing
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• 제4권5호
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• pp.318-323
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• 2015

We present a new way to create a thermally stable, highly strained germanium (Ge) optical resonator using a novel Ge-on-dual-insulators substrate. Instead of using a conventional way to undercut the oxide layer of a Ge-on-single-insulator substrate for inducing tensile strain in germanium, we use thin aluminum oxide as a sacrificial layer. By eliminating the air gap underneath the active germanium layer, we achieve an optically insulating, thermally conductive, and highly strained Ge resonator structure that is critical for a practical germanium laser. Using Raman spectroscopy and photoluminescence experiments, we prove that the novel geometry of our Ge resonator structure provides a significant improvement in thermal stability while maintaining good optical confinement.

• 한국표면공학회지
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• 제54권6호
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• pp.307-314
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• 2021

Diamond-like carbon (DLC) is difficult to achieve sufficient adhesion because of weak bonding between DLC film and the substrate. The purpose of this study is to improve the adhesion between substrate and DLC film. DLC film was deposited on AISI H13 using linear ion source. To improve adhesion, the substrate was treated by dual post plasma nitriding. In order to define the mechanism of the improvement in adhesive strength, the gradient layer between substrate and DLC film was analyzed by Glow Discharge Spectrometer (GDS) and Scanning Electron Microscope (SEM). The microstructure of the DLC film was analyzed using a micro Raman spectrometer. Mechanical properties were measured by nano-indentation, micro vickers hardness tester and tribology tester. The characteristic of adhesion was observed by scratch test. The adhesion of the DLC film was enhanced by active screen plasma nitriding layer.

• 한국인터넷방송통신학회논문지
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• 제17권6호
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• pp.151-160
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• 2017

지역의 관광지 및 문화를 체험 콘텐츠로 개발하는 방법 중 고화질의 비디오 영상을 대형 디스플레이에 표시하는 게 일반적인 방식으로 체험자의 능동적 참여와 다른 지역의 영상 체험과의 특별한 차별성이 필요하게 된다. 본 논문은 단분자 OLED와 능동형을 사용하여 지역의 명소를 투명 OLED 듀얼 레이어 디스플레이 시스템과 확장형 영상 구현 및 증강형 인터렉션 기법을 융합하여 체험자에게 새로운 경험과 아름다운 명소에 직접 와 있는 것과 같은 현실감 있는 체험을 제공 한다. 본 논문에서는 영상의 레이어에 추가적인 영상과 UI 레이어를 입혀 관광지 정보, 날씨, 지도, 숙박, 축제, 사진 자료등을 영상과 함께 체험할 수 있도록 하였으며, 듀얼 레이어 시스템 외에 추가로 양단에 세로형 55인치 디스플레이를 보조적으로 각각 1대씩 추가 연동하는 멀티 디스플레이 시스템을 더해 체험자에게 웅장한 몰입감과 인터페이스 연동의 재미를 더할 수 있도록 구현하였으며, 투명 OLED 및 듀얼 레이어 패널과 3채널 멀티 영상 재생 기법을 활용하여 한국의 전라남도 지역의 명소를 시공간의 제약 없이 상시 체험 가능한 증강형 체험 콘텐츠을 개발하였다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.140-145
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• 2018

Bulky carbon layer uniformly distributed with nanoscale $Fe_2O_3$ was prepared via a direct carbonation of $Fe^{3+}$-polyacrylonitrile complexes at $700^{\circ}C$ under $N_2$ flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ${\sim}810mAh\;g^{-1}$ after 250 cycles at a current rate of $100mA\;g^{-1}$. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active $Fe_2O_3$ during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.208-211
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• 1997

We have fabricated a single-electron-tunneling(SET) transistor with a dual gate geometry based on the SOI structure prepared by SIMOX wafers. The split-gate is the lower-gate is the lower-level gate and located ∼ 100${\AA}$ right above the inversion layer 2DEG active channel, which yields strong carrier confinement with fully controllable tunneling potential barrier. The transistor is operating at low temperatures and exhibits the single electron tunneling behavior through nano-size quantum dot. The Coulomb-Blockade oscillation is demonstrated at 15mK and its periodicity of 16.4mV in the upper-gate voltage corresponds to the formation of quantum dots with a capacity of 9.7aF. For non-linear transport regime, Coulomb-staircases are clearly observed up to four current steps in the range of 100mV drain-source bias. The I-V characteristics near the zero-bias displays typical Coulomb-gap due to one-electron charging effect.

• 한국전자파학회논문지
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• 제28권5호
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• pp.355-365
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• 2017

본 논문에서는 간접급전 패드를 이용한 이중 대역 GPS 패치 안테나를 제안하였다. 제안된 안테나는 GPS L1 대역에서 공진하는 상부패치, L2 대역에서 공진하는 하부패치, 중간층에 위치하는 2개의 간접급전 패드로 구성되며, 광대역 원형 편파 특성구현을 위해 하이브리드 칩커플러를 사용하여 두 급전 포트 사이에 $90^{\circ}$의 위상차를 갖도록 급전하였다. 제안된 개별 안테나의 측정 결과, 전면 방향 이득은 GPS L1, L2 대역에서 각각 3.0 dBic, 5.1 dBic를 나타내며, 축비 특성은 각각 3.3 dB, 0.3 dB를 나타내는 것을 확인하였다. 제안된 안테나를 동일한 유전체 기판 가장자리에 7소자 배열하여 제작하여 active element pattern을 측정한 결과, 전면 방향 이득은 GPS L1, L2 대역에서 각각 -0.4 dBic, -2.4 dBic를 나타내어 GPS 배열안테나의 개별 소자로 사용 가능함을 확인하였다.