• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.350-353
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• 1998

Recently, local governments have started projects of implementing Geographic Information Systems (GIS) as an infrastructure for the collection, storage, and analysis of the spatial information. So far, these projects have been approached from the areas such as the civil engineering and the computer science perspectives. Nonetheless, in order for a GIS project to be successful, it should be approached from the management perspectives as well. In this paper, the authors discusses about the management issues such as the determination of priority of the sub-projects, the organizational structure that takes charge of the project and the evaluation of the performance of the project.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2013년 추계학술대회
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• pp.569-578
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• 2013

This paper which took effect in September 2011 to comply with the Privacy Act were studied in terms of the provisions for penalties. Article 70 to 75 of Privacy Act in was considered with mandatory provisions of items, and for the compliance required actions was developed and item indexing according to collection, use, offer, charge, destroying of life cycle of personal information.

• 대한전기학회논문지
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• 제33권6호
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• pp.203-211
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• 1984

MOS silicon solar cells have been developed using the fixed (interface) charge inherent to thermally oxidized silicon to induce an n-type inversion layer in 1-10 ohm-cm p-type silicon. Higher collection efficiencies are predicted than for diffused junction cells. Without special precautions a conversion efficiency of 14.2% is obtained. A MOS silicon solar cell is described in which an inversion layer forms the active area which is then contacted by means of a MOS grid. The highest efficiency is obtained when the resistivity of the substrate is high.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.670-674
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• 2012

The photovoltaic performance of solid-state dye-sensitized solar cells employing hole transport material (HTM), 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9'-spirobifluorene (spiro-MeOTAD), has been investigated in terms of HTM overlayer thickness. Two important parameters, soak time and spin-coating rate, are varied to control the HTM thickness. Decrease in the period of loading the spiro-MeOTAD solution on $TiO_2$ layer (soak time) leads to decrease in the HTM overlayer thickness, whereas decrease in spin-coating rate increases the HTM overlayer thickness. Photocurrent density and fill factor increase with decreasing the overlayer thickness, whereas open-circuit voltage remains almost unchanged. The improved photocurrent density is mainly ascribed to the enhanced charge transport rate, associated with the improved charge collection efficiency. Among the studied HTM overlayer thicknesses, ca. 230 nm-thick HTM overlayer demonstrates best efficiency of 4.5% at AM 1.5G one sun light intensity.

• Advances in nano research
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• 제2권1호
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• pp.23-56
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• 2014

The significant growth of the Si photovoltaic industry has been so far limited due to the high cost of the Si photovoltaic system. In this regard, the most expensive factors are the intrinsic cost of silicon material and the Si solar cell fabrication processes. Conventional Si solar cells have p-n junctions inside for an efficient extraction of light-generated charge carriers. However, the p-n junction is normally formed through very expensive processes requiring very high temperature (${\sim}1000^{\circ}C$). Therefore, several systems are currently under study to form heterojunctions at low temperatures. Among them, carbon nanotube (CNT)/Si hybrid solar cells are very promising, with power conversion efficiency up to 15%. In these cells, the p-type Si layer is replaced by a semitransparent CNT film deposited at room temperature on the n-doped Si wafer, thus giving rise to an overall reduction of the total Si thickness and to the fabrication of a device with cheaper methods at low temperatures. In particular, the CNT film coating the Si wafer acts as a conductive electrode for charge carrier collection and establishes a built-in voltage for separating photocarriers. Moreover, due to the CNT film optical semitransparency, most of the incoming light is absorbed in Si; thus the efficiency of the CNT/Si device is in principle comparable to that of a conventional Si one. In this paper an overview of several factors at the basis of this device operation and of the suggested improvements to its architecture is given. In addition, still open physical/technological issues are also addressed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.467.1-467.1
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• 2014

Quantum dots (QD) solar cells has received considerable attention due to their potential of improving the overall conversion efficiency by harvesting excess energy via multiple excitons generation (MEG). Although there have been many reports which show MEG phenomena by using optical measurement of quantum dots themselves, carrier multiplication in real QD photovoltaic devices has been sparsely reported due to difficulty in dissociation of excitons and charge collection. In this reports, heterojunction QD solar cells composed of PbS QD monolayer on highly crystalline $TiO_2$ thin films were fabricated by using Langmuir-Blodgett deposition technique to significantly reduce charge recombination at the interfaces between each QD. The PbS CQDs monolayer was characterized by using UV-vis, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The internal quantum efficiency (IQE) for the monolayer QD solar cells was obtained by measurement of external quantum efficiency and determining light absorption efficiency of active layer. Carrier multiplication was observed by measuring IQE greater than 100% over threshold photon energy. Our findings demonstrate that monolayer QD solar cell structure is potentially capable of realizing highly efficient solar cells based on carrier multiplication.

• 한국산학기술학회논문지
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• 제3권3호
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• pp.194-197
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• 2002

이온교환은 액체상 이온과 고체상 이온간의 화학반응이며 연수 및 탈염공정, 특정물질의 제거 및 회수, 토양을 통한 이온성 물질의 이동에서 널리 이용되고 있다. 이온 선택도는 원자가가 높을수록, 수화반경이 작을수록 증가한다. 본 연구는 평형 이온교환에서 결정된 이온 선택도가 칼럼 이온교환에 적용되는 가를 조사하였다. 음이온 교환수지에 대한 이온 선택도 순서는 OH/sup -/ < F/sup -/ < HCO/sup -/ < Cl/sup -/ < Br/sup -/ ≤ NO₃/sup -/ < SO₄/sup 2-/ 이였으며, 음이온 칼럼교환에서도 동일하였다. 또한 바탕 양이온의 전하가 낮을수록 이온교환이 빠르게 진행됨을 알 수 있었다.

• Asian Journal of Atmospheric Environment
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• 제9권2호
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• pp.137-145
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• 2015

This study focused on the measurement of the actual charging state of ambient aerosol particles, which is important for understanding the intricate process of adverse health effects caused by particulate matter (PM). The net electrostatic charging state of $PM_{2.5}$ collected on filter media was measured in this study. The Faraday cage method and surface potential measurements were used in this study. The results showed that the polarities of the net charging state measured using these two methods were in agreement for 42 out of 48 samples (87.5%), and 36 samples (75%) were negatively charged. The filters were not significantly charged by friction between the filters and air not containing PM. Charge addition to or leakage from the filters was not observed over a two-month storage period. Net charging state of $PM_{2.5}$ collected on the filters was concluded to be negative in most cases, based on data's support of the assumption that aerosol charging state is not altered by the process of PM collection using filter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.388-391
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• 2003

The properties of these detectors can be controlled by electronics and exposure conditions. Flat-panel detectors for digital diagnostic imaging convert incident x-ray images to charge images. Flat panel detectors gain more interest real time medical x-ray imaging. Active area of flat panel detector is $14{\times}17$ inch. Detector is based on a $2560{\times}3072$ away of photoconductor and TFT pixels. X-ray conversion layer is deposited upper TFT array flat panel with a 500m by thermal deposition technology. Thickness uniformity of this layer is made of thickness control technology(5%) of thermal deposition system. Each $139m{\times}139m$ pixel is made of thin film transistor technology, a storage capacitor and charge collection electrode having geometrical fill factor of 86%. Using the separate driving system of two dimensional mosaic modules for large area, that is able to 4.2 second per frame. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system..