• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.11-11
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• 2010

Thin-film-transistors (TFTs) that can be deposited at low temperature have recently attracted lots of applications such as sensors, solar cell and displays, because of the great flexible electronics and transparent. Transparent and flexible transistors are being required that high mobility and large-area uniformity at low temperature [1]. But, unfortunately most of TFT structures are used to be $SiO_2$ as gate dielectric layer. The $SiO_2$ has disadvantaged that it is required to high driving voltage to achieve the same operating efficiency compared with other high-k materials and its thickness is thicker than high-k materials [2]. To solve this problem, we find lots of high-k materials as $HfO_2$, $ZrO_2$, $SiN_x$, $TiO_2$, $Al_2O_3$. Among the High-k materials, $Al_2O_3$ is one of the outstanding materials due to its properties are high dielectric constant ( ~9 ), relatively low leakage current, wide bandgap ( 8.7 eV ) and good device stability. For the realization of flexible displays, all processes should be performed at very low temperatures, but low temperature $Al_2O_3$ grown by sputtering showed deteriorated electrical performance. Further decrease in growth temperature induces a high density of charge traps in the gate oxide/channel. This study investigated the effect of growth temperatures of ALD grown $Al_2O_3$ layers on the TFT device performance. The ALD deposition showed high conformal and defect-free dielectric layers at low temperature compared with other deposition equipments [2]. After ITO was wet-chemically etched with HCl : $HNO_3$ = 3:1, $Al_2O_3$ layer was deposited by ALD at various growth temperatures or lift-off process. Amorphous InGaZnO channel layers were deposited by rf magnetron sputtering at a working pressure of 3 mTorr and $O_2$/Ar (1/29 sccm). The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. The TFT devices were heat-treated in a furnace at $300^{\circ}C$ and nitrogen atmosphere for 1 hour by rapid thermal treatment. The electrical properties of the oxide TFTs were measured using semiconductor parameter analyzer (4145B), and LCR meter.

• 전자공학회논문지SC
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• 제47권5호
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• pp.1-8
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• 2010

시장과 공장 환경 변화에 따라 생산관리의 용이성, 조작의 편리성, 높은 산업 안정성등의 요구가 본 논문에서는 네트워크기반의 시스템을 도입하여 단점을 보완한 새로운 고속, 초정밀 취출 로봇 제어기를 개발하였다. 개발된 제어기는 크게 티칭 팬던트와 중앙 서버 PC로 구분된다. 중앙 서버 PC는 관리자에게 전체 공정에 관련된 정보를 제공하게 된다. 티칭 팬던트는 중앙 서버 PC와 사출물 취출 로봇에 다리 역할로 사출로봇을 이용하는 사용자에게 제어 기능 및 사용자 인식, 금형파일 관리등 다양한 기능을 제공하게 된다. 사출물 취출을 위한 제어기 개발은 소프트웨어와 하드웨어 부분으로 나누어진다. 소프트웨어 개발은 3단계로 구분된다. 응용 프로그램과 유저 인터페이스 그리고 디바이스 드라이버로 구분되며, 간단한 디바이스 드라이버에는 따로 구분하지 않고 응용 프로그램에 포함되어 사용하도록 하였다. 하드웨어는 터치패널과 무선 네트워크를 도입하여 인터넷 접속 및 효율적인 공정 제어를 구축할 수 있도록 하였다. 기존의 시스템의 취출 싸이클이 5초였으나, 개선된 시스템을 도입하였을 경우 4초이내였으며, 다양한 무선 네트워크 기능으로 인한 공정 관리 및 생산 관리등 공정의 효율성을 높일 수 있었다.

• 한국산림과학회지
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• 제105권2호
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• pp.231-237
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• 2016

본 연구는 국내 벌채현장에서 가장 많이 활용되고 있는 Woodgrab에 의한 단목집재작업이 생산성 및 수익성 측면에서 가장 유리한 방식인가에 대한 검토를 하고자 수행되었다. 이를 위해 Woodgrab 목재수확방법의 생산성 및 수익성을 비교하기 위하여 Swing yarder와 Tower yarder에 의한 전목집재작업을 선정하였다. 이를 토대로 낙엽송 임분에 대한 작업기종별 조재지침을 적용하여 각 기종별 수확작업과정에 따른 작업비용과 등급별 원목매각 순수익을 산출하여 비교하였다. 연구결과, Woodgrab을 이용한 단목집재작업은 Swing yarder 혹은 Tower yarder에 의한 전목집재작업에 비해 생산성이나 생산단가 측면에서 유리한 반면 원목생산의 수익성 측면에서는 오히려 불리한 것으로 나타났다. 이것은 Woodgrab에 의한 목재생산작업을 하는 경우 생산비가 절감되는 대신 시장가격이 낮은 펄프, 보드류 혹은 톱밥 등의 원료재로 사용되는 단목을 주로 생산할 수 밖에 없는 것에 기인한 것이다.

• 천문학회보
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• 제42권2호
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• pp.57.1-57.1
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• 2017

Automatic observing is the most efficient system for sky surveys that image many targets over large areas of the sky. Such a system requires the integrating control software that systematically manages astronomical instruments that are not connected to each other. In February of 2017, we installed a wide-field 10 inch telescope for Supernovae survey on the McDonald 30 inch telescope as a piggyback system. However, during the observations, information such as target coordinates could not be exchanged with the telescope mount. The reason is the program that controls the telescope control system (TCS) and the program that controls the imager operate on independent PCs. KAOS30 is an integrated observing software developed to improve this environment. The software is composed of four packages that are the Telescope Control Package (TCP), the Data Acquisition Package (DAP), the Auto Focus Package (AFP), and the Script Mode Package (SMP). The TCP communicates to the TCS and also communicates weather information. SMP supports automatic observing in a script mode, which improves the efficiency of the survey. KAOS30 was developed based on Visual C ++ and runs on the Windows operating system. It also supports the ASCOM driver platform for various manufacturers. The instruments that support ASCOM can be installed without modification of the program code. KAOS30 can be applied as software for many different telescopes in future projects.

• Asia pacific journal of information systems
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• 제19권3호
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• pp.151-179
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• 2009

The purpose of this study is to make an empirical analysis on the factors affecting the intention for the continuous use of the BSC system, which has been recently spread in the public sector. Because the object of acceptance is the performance management system based on BSC (Balanced Scorecard) implemented in the form of information systems, this study proposes a research model by applying TAM (Technology Acceptance Model). Independent variables are factors affecting the acceptance of BSC system such as training, communication, IS support, CEO support and personal innovativeness, and we examine their effects on the dependent variable, namely, intention on continuous use via mediating variables: perceived usefulness and perceived ease of use. A questionnaire survey was conducted with public institutions(firms) that had introduced and were operating the BSC system; 264 valid questionnaires are adopted. Collected data are analyzed using SPSS 16.0 and AMOS 7.0. Results of reliability test show that all analyzed data are reliable. In validity test, one item regarding communication was excluded; 9 latent variables and 34 observed variables are used in the final analysis. Based on the results of the hypothesis test through path analysis using a structural equation model, 10 out of 16 hypotheses are accepted. Factors affecting perceived usefulness are training and IS(Information System) support. The analysis results indicate that perceived ease of use is mainly affected by IS support, CEO support, and personal innovativeness among the factors related to the acceptance of the BSC system. This suggests that, contrary to the expectation that the BSC system may be used without difficulty, the management's active support is required in order to attain expected improvement in productivity and work efficiency. This was also pointed out in case studies on the construction of the BSC system in public sectors. On the other hand, perceived ease of use is found to affect perceived usefulness. This supports the results of previous researches on TAM. Perceived ease of use and perceived usefulness are found to affect the attitude towards the use of the system. The intention on continuous use is affected more by perceived usefulness than by the attitude towards the use of system. This result supports the results of previous researches on TAM, showing that the BSC system is utilized substantially in worksites. This study is considered meaningful in that it was actually performed on users at public institutions(firms) that had introduced the BSC system and that it empirically tested hypotheses on the acceptance of the BSC system by applying TAM to the research model.

• 대한기계학회논문집B
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• 제36권2호
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• pp.171-179
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• 2012

고온부에 해당하는 터빈 노즐과 로터의 냉각은 가스터빈의 성능에 큰 영향을 미친다. 본 연구에서는 냉각 공기의 예냉각이 가스터빈과 복합화력 발전 성능에 미치는 영향을 알아보았다. 계산에 사용된 모델은 F-Class 가스 터빈이며 냉각을 고려한 터빈의 구성요소를 사용해 냉각공기의 변화에 대해 보다 정확한 모사를 구사하였다. 냉각공기의 예냉각에 따른 가스터빈의 성능변화를 나타내기 위해 탈설계 해석이 수행되었다. 노즐 및 로터의 냉각에 따른 성능 변화를 보다 정확하게 나타내기 위해 열역학적 냉각모델과 속도삼각형을 고려한 모델이 고려되었다. 또한 복합발전의 경우 냉각공기에서 추출된 열을 하부사이클에서 회수하여 스팀터빈을 구동하는데 추가적인 열을 공급하는 시스템이 구성되었다. 복합발전 시스템의 모든 냉각공기의 온도를 200K 예냉각하는 경우에 주유동가스의 유량증가로 인해 약 1.78%의 출력 증가를 나타내었으며 동일한 터빈 입구온도 유지를 위한 연료소모의 증가로 효율은 0.70% 포인트 감소하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1261-1265
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• 2003

Axial piston pumps of bent axis have been commonly used in hydraulic systems because of high pressure level. best efficiency, low shear force on pistons and low operating costs. The other side, they have a few demerits like that they have the relatively high number of moving parts and more discharge pressure ripples. Especially, the discharge pressure ripples bring about vibrations and noises in hydraulic system components such as connecting pipes and control valves, so that these deteriorate the stability and accuracy of the systems. Therefore, the hydraulic systems having the axial piston pumps of bent axis require the methods to reduce the discharge pressure ripples. So, the purpose of this paper is to reduce the discharge pressure ripples by the phase interference of pressure wave and to develope the analysis model of the pumps to predict the discharge pressure ripples. In this paper, the analysis model of the axial piston pumps of bent axis was developed using the AMESim software, and the reliability of that was verified by the comparison with the experimental results. The hydraulic pipeline with a parallel line was used as the method to generate the phase interference of pressure wave. the dynamics characteristics of the hydraulic pipeline with a parallel line were analyzed by a transfer matrix method. the usefulness of the phase interference of pressure wave was investigated through the experiment and simulation. The results from the experiment and simulation said that the phase interference of pressure wave by the hydraulic pipeline with a paralle linel could reduce the discharge pressure wave of the pump well. The analysis model of the axial piston pumps of bent axis developed in this paper and the method of the phase interference by the hydraulic pipeline with a parallel line are expected to be helpful to achieve the design of the pump and to reduce the discharge pressure wave of the pump effectively.

• 대한기계학회논문집B
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• 제40권1호
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• pp.39-45
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• 2016

차량용 연료전지의 부하 변동시 열관리는 성능과 내구성에 직결되기 때문에 매우 중요하다. 본 연구에서는 작동 부하 조건 내에 온도를 유지할 수 있도록 하기 위한 열관리 시스템용 선형 상태 궤환 제어기를 설계하였다. 차량용 연료전지 열관리 모델은 레저버, 라디에이터, 바이패스 밸브, 팬 그리고 냉각수 펌프 등으로 구성하였으며, MATLAB/SIMULINK$^{(R)}$으로 개발하였다. 시스템 모델의 비선형성으로 인해, 부하 조건 $0.5A/cm^2{\sim}0.7A/cm^2$ 에서 온도 제어 지령을 정상적으로 달성하기 위해 PWM(Pulse Width Modulation)과 수정된 상태 궤환 제어기를 적용하였고 제어 알고리즘의 성능은 ITAE(Integral time weighted error)로 평가하였다. 수정된 상태 궤환 제어기가 저 부하 구간에서 다른 알고리즘에 비해 더 효율적으로 온도를 제어하는 것을 확인하였다.

• 대한전자공학회논문지SD
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• 제49권1호
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• pp.15-24
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• 2012

본 논문에서는 Switched-Capacitor 지연 기법의 새로운 고해상도 DPWM 발생기를 사용한 Dynamic-Response-Free SMPS를 제안한다. 제안된 회로는 Switched-Capacitor 지연 기법을 이용한 DPWM 발생기의 내부 커패시터 전압 기울기를 제어하는 방식으로 DPWM의 duty ratio를 결정한다. 제안된 회로는 컨버터의 피드백 전압과 기준전압을 비교하여 DPWM 발생기의 내부 캐패시터에 충방전되는 전류량을 제어하는 방식으로 출력전압 tracking이 가능하다. 따라서 제안된 회로는 기존 closed loop 제어 방식의 SMPS들에서 문제점이 되고 있는 동적 응답특성을 고려할 필요가 없으며, 출력 전압에 overshoot/undershoot로 인한 ringing 현상이 발생하지 않는다는 큰 장점을 가진다. 제안된 회로는 1MHz~10MHz까지 스위칭주파수를 사용자가 선택할 수 있으며, 100MHz의 내부 제어 동작 주파수로 10MHz 최대 스위칭 주파수(DPWM) 발생이 가능하다. 100MHz의 내부 제어 동작 주파수를 사용하여 10MHz 스위칭 주파수 발생시 소모되는 내부 회로의 최대 전류는 2.7mA이며, 출력 버퍼를 포함한 전체 시스템의 전류 소모는 15mA이다. 제안된 회로는 0.125%의 DPWM duty ratio 해상도를 가지고 부하에 최대 1A까지 전류공급이 가능하며, 최대 리플 전압은 8mV이다. 동부하이텍 BCD $0.35{\mu}m$ 공정 파라미터를 이용해 시뮬레이션을 수행하여 제안된 회로의 동작을 검증하였다.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.479-487
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• 2015

The thallium-doped sodium iodide [NaI(Tl)] scintillation detector is preferred as a gamma spectrometer in many fields because of its general advantages. A silicon photomultiplier (SiPM) has recently been developed and its application area has been expanded as an alternative to photomultiplier tubes (PMTs). It has merits such as a low operating voltage, compact size, cheap production cost, and magnetic resonance compatibility. In this study, an array of SiPMs is used to develop an NaI(Tl) gamma spectrometer. To maintain detection efficiency, a commercial NaI(Tl) $2^{\prime}{\times}2^{\prime}$ scintillator is used, and a light guide is used for the transport and collection of generated photons from the scintillator to the SiPMs without loss. The test light guides were fabricated with polymethyl methacrylate and reflective materials. The gamma spectrometer systems were set up and included light guides. Through a series of measurements, the characteristics of the light guides and the proposed gamma spectrometer were evaluated. Simulation of the light collection was accomplished using the DETECT 97 code (A. Levin, E. Hoskinson, and C. Moison, University of Michigan, USA) to analyze the measurement results. The system, which included SiPMs and the light guide, achieved 14.11% full width at half maximum energy resolution at 662 keV.