• Journal of Photoscience
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• 제10권1호
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• pp.105-119
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• 2003

Fullerenes, $C_{60}$ and $C_{70}$, display interesting physicochemical properties in solutions, especially due to their unique chemical structures and their good electron accepting abilities. Solubility of fullerenes in different organic solvents and their unusual solvatochromic behavior, the ability of the fullerenes to form aggregates in solutions, and their electron transfer and charge transfer interactions with variety of electron donors, are the subjects of extensive research activities for more than one decade. Many research groups including ours have contributed substantially in the understanding of the solvatochromism, aggregation behavior, and the photoinduced electron transfer and charge transfer chemistry of fullerenes, in condensed phase. Present article is aimed to summarize the important results reported on the above aspects of fullerenes, subsequent to the earlier report from our group (D.K. Palit and J.P. Mittal, Full. Sci. & Tech. 3, 1995, 643-659).)., 643-659)..

• Structural Engineering and Mechanics
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• 제43권6호
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• pp.835-845
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• 2012

This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

• 전기전자학회논문지
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• 제27권1호
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• pp.30-37
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• 2023

양자점 발광 다이오드(QD-LED)의 효율과 안정성 향상을 위해서 QD 발광층에 주입되는 전하의 균형을 이루는 것은 필수이다. 산화 아연(ZnO)은 최신 QD-LED에서 전자수송층(electron transport layer, ETL)을 구성하기 위해 가장 많이 사용되고 있으나, ZnO의 자발적인 전자 주입은 QD-LED의 성능을 크게 열화시키는 과도한 전자 주입을 유발한다. 본 연구에서는 자기조립단분자막(self-assembled monolayer, SAM) 처리를 통해 ZnO의 전자 주입 특성을 조절하여 QD-LED의 성능을 향상시켰다. 전하 균형도를 향상시킨 결과, SAM을 처리한 QD-LED는 SAM을 처리 안한 소자와 비교하여 내부 양자 효율(external quantum efficiency, EQE)이 25%, 최대 휘도는 200% 향상되었다.

• 가정과삶의질연구
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• 제24권1호
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• pp.43-53
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• 2006

The purpose of this study was to explore the attitudes about the management service charge in multi-family housing. Recently, increasing needs of urban families in residential housing management services were apparent in many studies, but the way that they charge for the management services was not dear. Research method was social survey with questionnaire from 484 residents and 84 housing managers of multi-family housing in Seoul and new town area. Research results showed that residents recognized the management services should be free of charge or imposed actual expenses, but managers recognized the management services as charged services. To provide efficient housing management services for residents in multi-family housing, human resources should be inputted. Therefore, this study suggested that the participation of residents in housing management service is recommendable as a way of lessen the economic burden of management service charge, but also to have an opportunity to interest in their community activities.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1931-1938
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• 2021

Uranium ingot is produced by metallothermic reduction of uranium tetrafluoride using magnesium or calcium as reductant. Presence of oxygen containing compounds viz. uranyl fluoride and uranium oxide in the starting uranium fluoride has a significant effect on the firing time, final temperature of the charge, slag-metal separation and hence the metal recovery. As reported in the literature, the maximum tolerable limit for uranyl fluoride in the UF₄ is 2.5 wt% and limit for uranium oxide content is in the range 2-3 wt%. No theoretical or experimental basis is available till date for these limits. Analyses have been carried out in this study to understand the effect of UO₂F₂ concentration in the starting fluoride on the final temperature of the products and thus the reduction characteristics. UF₄ having uranyl fluoride concentration, less than as well as more than 2.5 wt%, have been investigated. Thermodynamic calculations have been carried out to arrive at a general expression for the final temperature attained by the products during calciothermic reduction of UF₄. Finally, an upper limit for the oxygen containing impurities has been estimated using the CaO-CaF₂ phase diagram.

• 전기화학회지
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• 제11권2호
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• pp.100-104
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• 2008

Titanium sheet metal substrates used in thin film batteries were wet etched and their surface area was increased in order to increase the discharge capacity and power density of the batteries. To obtain a homogeneous etching pattern, we used a conventional photolithographic process. Homogeneous hemisphere-shaped wells with a diameter of approximately $40\;{\mu}m$ were formed on the surface of the Ti substrate using a photo-etching process with a $20\;{\mu}m{\times}20\;{\mu}m$ square patterned photo mask. All-solid-state thin film cells composed of a Li/Lithium phosphorous oxynitride (Lipon)/$LiCoO_2$ system were fabricated onto the wet etched substrate using a physical vapor deposition method and their performances were compared with those of the cells on a bare substrate. It was found that the discharge capacity of the cells fabricated on wet etched Ti substrate increased by ca. 25% compared to that of the cell fabricated on bare one. High discharge rate was also able to be obtained through the reduction in the internal resistance. However, the cells fabricated on the wet etched substrate exhibited a higher degradation rate with charge-discharge cycling due to the nonuniform step coverage of the thin films, while the cells on the bare substrate demonstrated a good cycling performance.

• 대한한의학회지
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• 제28권3호통권71호
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• pp.1-12
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• 2007

Objectives : The purpose of this study was to explore the perceptions of health promotion programmes using traditional Korean medicine among public health centre staff in charge of running such programmes. To do so, we examined and analysed the current situation of implementing the programmes in the public health centre. Methods : A survey was designed to collect information on perception of the health promotion programmes using traditional Korean medicine by public health centre staff in charge of running such programmes. The survey, using a structured questionnaire designed for this study, was conducted on 161 public health centre staff attending an annual meeting to presenting the results of activity evaluation related to public health programmes using traditional Korean medicine in public health centres. The participants were asked about the most successful programme, the benefits of the programmes, the positive aspects of the programmes, the most desirable outcomes of the programmes and so on. The data were analysed using SPSS system 12.0 for Windows. Results : Of the 161 questionnaires, 121 were analysed. The main findings of this research were as follows. Of the health promotion programmes using traditional Korean medicine implemented in public health centres, qigong and stroke preventive health promotion programmes were perceived as the most successful. The major benefits of the programmes were having merit for health promotion and expecting a positive performance outcome. The major positive aspects of the programmes for health promotion were cultivating community citizen's support and showing consistency between the philosophy of the programmes and the direction of existing health promotion programmes. The most desirable outcomes of the programmes were spreading community understanding of the programme and establishing an effective and unique health promotion model for implementing the programme. Two major causes of implementation difficulties were lack of material resources such as manpower, facility, and equipment, and methods of performance evaluation. One of the most urgent needs for activating the implementation of programmes was continuing financial and technical support from the central government. Conclusions : To promote the role of traditional Korean medicine in the public health sector in order to integrate traditional medicine into the public health system, government should develop some measures for solving the identified causes of implementation difficulties and coping with the most urgent needs for activating the implementation of programmes.

• Advances in nano research
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• 제4권1호
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• pp.1-14
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• 2016

Superparamagnetic iron oxide nanoparticles (Nps), composed of magnetite, $Fe_3O_4$, or maghemite, ${\gamma}-Fe_2O_3$, core and biocompatible polymer shell, such as dextran or chitozan, have recently found wide applications in magnetic resonance imaging, contrast enhancement and hyperthermia therapy. For different diagnostic and therapeutic applications, current attempt is focusing on the synthesis and biomedical applications of various ferrite Nps, such as $CoFe_2O_4$ and $MnFe_2O_4$, differing from iron oxide Nps in charge, surface chemistry and magnetic properties. This study is focused on the synthesis of manganese ferrite, $MnFe_2O_4$, Nps by most commonly used chemical way pursuing better control of their size, purity and magnetic properties. Co-precipitation syntheses were performed using aqueous alkaline solutions of Mn(II) and Fe(III) salts and NaOH within a wide pH range using various hydrothermal treatment regimes. Different additives, such as citric acid, cysteine, glicine, polyetylene glycol, triethanolamine, chitosan, etc., were tested on purpose to obtain good yield of pure phase and monodispersed Nps with average size of ${\leq}20nm$. Transmission electron microscopy (TEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), $M\ddot{o}ssbauer$ spectroscopy down to cryogenic temperatures, magnetic measurements and inductively coupled plasma mass spectrometry were employed in this study.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.745-752
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• 2024

A method for gamma/neutron event classification based on frequency-domain analysis for mixed radiation environments is proposed. In contrast to the traditional charge comparison method for pulse-shape discrimination, which requires baseline removal and pulse alignment, our method does not need any preprocessing of the digitized data, apart from removing saturated traces in sporadic pile-up scenarios. It also features the identification of neutron events in the detector's full energy range with a single device, from thermal neutrons to fast neutrons, including low-energy pulses, and still provides a superior figure-of-merit for classification. The proposed frequency-domain analysis consists of computing the fast Fourier transform of a triggered trace and integrating it through a simplified version of the transform magnitude components that distinguish the neutron features from those of the gamma photons. Owing to this simplification, the proposed method may be easily ported to a real-time embedded deployment based on Field-Programmable Gate Arrays or Digital Signal Processors. We target an off-the-shelf detector based on a small CLYC (Cs2LiYCl6:Ce) crystal coupled to a silicon photomultiplier with an integrated bias and preamplifier, aiming at lightweight embedded mixed radiation monitors and dosimeter applications.

• Membrane and Water Treatment
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• 제6권2호
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• pp.141-160
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• 2015

This study aims to investigate the impacts of chemical cleaning on the performance of a reverse osmosis membrane. Chemicals used for simulating membrane cleaning include a surfactant (sodium dodecyl sulfate, SDS), a chelating agent (ethylenediaminetetraacetic acid, EDTA), and two proprietary cleaning formulations namely MC3 and MC11. The impact of sequential exposure to multiple membrane cleaning solutions was also examined. Water permeability and the rejection of boron and sodium were investigated under various water fluxes, temperatures and feedwater pH. Changes in the membrane performance were systematically explained based on the changes in the charge density, hydrophobicity and chemical structure of the membrane surface. The experimental results show that membrane cleaning can significantly alter the hydrophobicity and water permeability of the membrane; however, its impacts on the rejections of boron and sodium are marginal. Although the presence of surfactant or chelating agent may cause decreases in the rejection, solution pH is the key factor responsible for the loss of membrane separation and changes in the surface properties. The impact of solution pH on the water permeability can be reversed by applying a subsequent cleaning with the opposite pH condition. Nevertheless, the impacts of solution pH on boron and sodium rejections are irreversible in most cases.