• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.963-965
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• 2003

We have synthesized new hole transport materials(HTMs). Then we have fabricated structures of ITO/new HTM/$Alq_{3}$/EIL/Al. New HTM based devices have higher current density and lower turn-on voltage than TPD based devices. New HTMs have higher HOMO level than TPD. The new HTM based OLEDs have shown better current injection than the TPD based OLEDs, due to the lower injection barrier between ITO surface and HTM.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.497-500
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e.g. As, Cl). The charge transport properties of amorphous Selenium is decided on hole which is induced from metal to selenium in metal-selenium junction and which is transferred in a-Se bulk. This phenomenon is resulted of changing electric field owing to increasing of space charge by deep trap of a-Se bulk. In this paper, We dopped the chlorine to compensate deep hole trap and deposited blocking layer using dielectric material to prevent from increasing space charge for injection charge between metal electrode and a-Se layer. We compared space charge and the decreasing of trap density through measuring dark and photo current. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹

• 한국정밀공학회지
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• 제27권10호
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• pp.14-22
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• 2010

The most costly and time-consuming process in the fabrication of today's multi-layer circuit board is drilling interconnection holes between adjacent layers and via holes within a layer. Decreasing size of via holes being demanded and growing number of via holes per panel increase drilling costs. Component density and electronic functionality of today's multi-layer circuit boards can be improved with the introduction of cost-effective, variable depth laser drilled blind micro via holes, and interconnection holes. Laser technology is being quickly adopted into the circuit board industry but can be accelerated with the introduction of a true production laser drilling system. In order to get optimized condition for drilling to FPCB (Flexible Printed Circuit Board), we use various drill pattern as drill step. For productivity, we investigate drill path optimization method. And for the precise drilling the thermal drift of scanner and temperature change of scan system are tested.

• 화약ㆍ발파
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• 제29권1호
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• pp.1-9
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• 2011

에어데크 공법은 노천광 및 대규모 발파현장에서 널리 쓰이는 대표적인 발파기술 중 하나이다. 에어데크 공법의 효율성 극대화를 위해 그간 많은 연구와 실험이 이루어졌으며, 공내에서 어떠한 압력 거동을 일으키는가를 규명하기 위한 노력들이 있었다. 본 연구에서는 다양한 에어데크 조건하에서 각 에어데크 구간이 어떠한 압력의 차이를 일으키는가에 대해 수치해석적으로 분석하였고, 에어데크의 위치와 에어데크 구간의 길이에 대한 압력변화를 알아보았다. 기본적으로 모든 수치해석은 JWL 상태방정식을 사용하였으며 2차원 평면상에서 진행 하였다. 순수한 압력의 변화만을 관찰하기 위해 암반의 밀도와 강도만을 달리하고 모든 암반은 균질한 상태로 가정하였다.

• 한국산학기술학회논문지
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• 제5권1호
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• pp.65-68
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• 2004

피스톤(piston)과 리바운드(rebound)를 1체형 소결품으로 제조하기 위하여는 후가공시 발생하는 홀(hole)부분의 막힘 현상, 홀 부분의 치수 편차 현상, 가공 응력 집중에 의한 부품 모서리(edge)부의 크랙 발생 현상 둥의 문제가 있다. 본 연구에서는 이와 같은 문제를 해결하기 위하여 성형체 및 소결체의 밀도 평가, hole 부분의 조직 평가(홀 내부 단차, 홀 내부의 버(burr) 발생 및 홀 크기), 소결체의 감쇠력 및 내구성 평가 등을 체계적으로 실시하여, 성형에서 발생하는 크랙, 홀 내부의 단차, 홀 크기의 문제점을 해결하였다.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.65-71
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• 2002

Characteristics of corona discharge of the different types of the plasma reactors which are cone-hole and cone-plate is investigated experimentally. The discharge starts at lower voltage for the cathode corona than the anode corona and spark occurs at higher voltage for the cathode corona. And the cathode corona makes more stable discharge than the anode corona. The effect of the base gas in corona discharge for different O$_2$/N$_2$ concentrations is related with the gas molecular weight. The discharge for the smaller molecular weight gas occurs easier than for the high molecular weight gas. The discharge current decreases with the increase of oxygen concentration and it increases more sharply for anode corona than for cathode corona as discharge voltage increases after corona onset voltage. NO-NO$_2$ conversion increases with the energy density of corona discharge and the addition of O$_2$ in a base N$_2$ gas.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.871-877
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al, glass substrate/ITO/Eu(TTA)$_3$(phen)/Al and glass substrate/ITO/Eu(TTA)$_3$(phen)/AlQ$_3$/Al structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and Tris(8-hydroxyquinoline) aluminu-m(AlQ$_3$) as an electron transporting layer. Electrolumescent(EL) and I-V characteristics of Eu(TTA)$_3$-(-phen) were investigated. These structures show the red EL spectra, which are almost the same at the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a operation voltage of 9V. Electrical transporting phenomena of these structures were explained using the trapped-charge-limited current model with I-V characteristics.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.475-478
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• 2004

we studied the effect of the type of non-thermal plasma on the decomposition of $CF_4$. 3 types of reactors were manufactured to generate different types of plasma respectively, and went into the experiments. As the results, we found that high density of the energy of non-thermal plasma and the minimization of non-discharged area should be met in order to elevate decomposition rate of $CF_4$. Among the reactors used in the study, the hole-type reactor was such one that satisfying that requirement. Using the hole-type reactor, treatment efficiency for high concentration of $CF_4$ was excellent. We got decomposition rate of more than 95[%] between 500[ppm] around and less than 400[ppm], and up to 85[%] at 900[ppm].

• 한국전기전자재료학회논문지
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• 제23권7호
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• pp.550-553
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• 2010

The enhancement of quantum efficiency using a surface modified Ag anode in top-emitting organic light emitting diodes (TEOLEDs) is reported. The operation voltage at the current density of $1\;mA/cm^2$ of TEOLEDs decreased from 9.3 V to 4.3 V as the surface of anode coated with $CuO_x$ layer. The work function of these structures were quantitatively determined using synchrotron radiation photoemission spectroscopy. Secondary electron emission spectra revealed that the work function of the Ag/$CuO_x$ structure is higher by 0.6 eV than that of Ag. Thus, the $CuO_x$ structure acts as a role in reducing the hole injection barrier by about 0.6 eV, resulting in a decrease of the turn-on voltage of top-emitting light emitting diodes.

• 한국멀티미디어학회논문지
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• 제22권6호
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• pp.676-683
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• 2019

Wireless Sensor Networks (WSNs) consist of multiple tiny and power constrained sensors which use radio frequencies to carry out sensing in a designated sensor area. To effectively design and implement reliable WSN, it is critical to consider models, protocols, and algorithms that can optimize energy consumption of all the sensor nodes with optimal amount of packet delivery. It has been observed that deploying a single sink node comes with numerous challenges especially in a situation with high node density and congestion. Sensor nodes close to a single sink node receive more transmission traffic load compared to other sensors, thus causing quick depletion of energy which finally leads to an energy hole and sink hole problems. In this paper, we proposed the use of multiple energy efficient sink nodes with brute force technique under optimized parameters to improve on the number of packets delivered within a given time. Simulation results not only depict that, deploying N sink nodes in a sensor area has a maximum limit to offer a justifiable improvement in terms of packet delivery ratio but also offers a reduction in End to End delay and reliability in case of failure of a single sink node, and an improvement in the network lifetime rather than deploying a single static sink node.