• 제목/요약/키워드: MD method

검색결과 628건 처리시간 0.023초

Desalination of geothermal water by membrane distillation

  • Gryta, M.;Palczynski, M.
    • Membrane and Water Treatment
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    • 제2권3호
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    • pp.147-158
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    • 2011
  • Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.

Impact of Corporate Governance Mechanisms on Corporate Social Responsibility Disclosure of Publicly-Listed Banks in Bangladesh

  • JAHID, Md. Abu;RASHID, Md. Harun Ur;HOSSAIN, Syed Zabid;HARYONO, Siswoyo;JATMIKO, Bambang
    • The Journal of Asian Finance, Economics and Business
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    • 제7권6호
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    • pp.61-71
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    • 2020
  • The study examines the impact of corporate governance mechanisms, such as board characteristics on corporate social responsibility disclosure (CSRD). The data on CSRD items and board characteristics have been collected by content analysis of the annual reports of 30 publicly-listed banks in Bangladesh covering six years, from 2013 to 2018. More specifically, the directors' report, the chairman's statement, notes to the financial statement and CSR disclosure reports included in annual reports were used to collect the CSRD data. The empirical analysis applies the ordinary least square and the generalized method of moments. The results of the study have revealed that board size, board independence, female board member, and foreign directors have a significant positive impact on CSRD. By contrast, political directors and audit committee size have a negative impact on CSRD. Interestingly, accounting experts on boards ensure more CSRD as they curb the influence of politicians on the board. Thus, it is better to increase accounting experts and decrease politicians on the board. These findings provide valuable insights into the process of forming a suitable CSR policy by connecting the efforts of the board, government, and regulatory bodies to enhance the performance of banks to CSR as well as to CSRD.

Intellectual Capital Disclosure and Its Determinants: Empirical Evidence from Listed Pharmaceutical and Chemical Industry of Bangladesh

  • Rahman, Md. Musfiqur;Sobhan, Raihan;Islam, Md. Shafiqul
    • Asian Journal of Business Environment
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    • 제9권2호
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    • pp.35-46
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    • 2019
  • Purpose - The purpose of this study is to find out the intellectual capital disclosure (ICD) and its determinants in the pharmaceutical and chemical industry of Bangladesh. Research design, data, and methodology - This research study is conducted on the listed firms of pharmaceutical and chemical industry in Bangladesh during the period of 2016 to 2017. This study develops a self-structured intellectual capital disclosure index; and the proxies of determinants of ICD are used as board characteristics (board size, independent directors and female directors), ownership structures (institutional ownership and director ownership), and firm characteristics (firm size, leverage and performance). The study uses a content analysis to analyze the extent of ICD and a pooled cross-sectional method to find the determinants of ICD. Research Findings - This study finds that intellectual capital disclosure is positively associated with firm size, leverage, and firm performance and negatively associated with director ownership and institutional ownership. This study also finds that there is no significant association of ICD with independent director or female director. Conclusions - The study recommends that the regulatory authority should develop mandatory guidelines on ICD for ensuring proper and consistent disclosure about the intellectual capitals. Besides, the companies should include a separate section in the annual reports to disclose the measurement and management of intellectual capital.

플라스틱 기판위의 기계적으로 유연성을 가진 PZT 박막 (Mechanically Flexible PZT thin films on Plastic Substrates)

  • 노종현;안종현;안정호;이내응;김상진;이환수
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 하계학술대회 논문집
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    • pp.13-13
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    • 2009
  • We have investigated the fabrication and properties of bendable PZT film formed on plastic substrates for the application in flexible memory. These devices used the PZT active layer formed on $SiO_2/Si$ wafer by sol-gel method with optimized device layouts and Pt electrodes. After etching Pt/PZT/Pt layers, patterned by photolithography process. these layers were transferred on PET plastic substrate using elastomeric stamp. The level of performance that can be achieved approaches that of traditional PZT. devices on rigid bulk wafers.

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Evaluation of Internal Structure and Morphology of Poly(benzyl ether) Dendrimers by Molecular Dynamics Simulations

  • Hong, Taewan;Kim, Hyung-Il
    • Macromolecular Research
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    • 제12권2호
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    • pp.178-188
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    • 2004
  • We performed molecular dynamics (MD) simulations at 300 K on a series of poly(benzyl ether) (PBE) dendrimers having a different core functionalities. We used the rotational isomeric state Metropolis Monte Carlo (RMMC) method to construct the initial configuration in a periodic boundary cell (PBC) before the MD simulations were undertaken. To elucidate the effects that the structural features have on the chain dimension, the overall internal structure, and the morphology, we monitored the radii of gyration, R$\sub$g/ and the conformational changes during the simulations. The PBE dendrimers in a glassy state adopted less-extended structures when compared with the conformations obtained from the RMMC calculations. We found that R$\sub$g/ of the PBE dendrimer depends on the molecular weight, M, according to the relation, R$\sub$g/∼M$\^$0.22/. The radial distributions of the dendrimers were developed identically in the PBC, irrespective of the core functionality. A gradual decrease in radial density resulted from the fact that the terminal branch ends are distributed all over the molecule, except for the core region.

Linkage between Public Policy, Green Technology and Green Products on Environmental Awareness in the Urban Kuala Lumpur, Malaysia

  • Saifullah, Md. Khaled;Kari, Fatimah Binti;Ali, Md. Arphan
    • The Journal of Asian Finance, Economics and Business
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    • 제4권2호
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    • pp.45-53
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    • 2017
  • The main purpose of this study is to investigate the factors that have an impact on public policy, green products and technology in Kuala Lumpur, given government initiatives to boost the environment awareness. The data used in this study was collected by distribution questionnaires randomly in six areas of Kuala Lumpur and 400 respondents were interviewed. Based on a literature review, three hypotheses were stated and tested using structural equation modeling (SEM). SEM is a statistical analysis method that involved two or more variables in analyzing structural relationships among the variables. The SEM model shows that green products and government policies have a direct influence on environmental awareness. However, green technology does not have a direct influence on environmental awareness. Since, knowledge on green technology does not have a significant impact on raising environmental awareness among the public, a much more pragmatic awareness campaign needs to be put in place to use green technology as a part of modern living. The study suggests that the urban population needs to be more aware of the environmental issue as cities tend to have better infrastructure to raise public awareness on green issues. Moreover, the government should increase the environmental awareness among younger generation through workshops, seminars, campaigns, and pamphlets.

배전용 변압기 온라인 감시와 진단을 위한 모니터링 프로그램 및 DB의 구축 (The Monitoring Program and Database Construction for Diagnosing Distribution Transformer in On-line)

  • 문종필;김재철;김동현;최준호;최도혁;김영춘
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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    • pp.177-179
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    • 2000
  • In this paper, we developed the online Monitoring & Diagnostic(MD) system of distribution transformers. It consists of the Data Acquisition(DA) module and the DataBase(DB) module. The acquired data from the distribution transformers is stored to the DB in an on-line. The DB is planned and made to the RDBMS (Relative DataBase Management System) to manage the data efficiently. The developed MD system estimates the loss of life from the DB. Thus, it could be managed the career and the functional lifetime of the transformer more efficiently than existing systems. In the case study, the oil temperature rising experiment is performed by using the back loading method in the laboratory level. From the results, the proposed MB system can be a practical applications for the distribution transformers.

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막증류 공정에서 PE 및 PVDF 중공사막의 액체투과압력 측정에 관한 연구 (Measurement of Liquid Entry Pressure of PE and PVDF Hollow Fiber Membranes in Membrane Distillation Process)

  • 민지희;박민수;김진호
    • 멤브레인
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    • 제25권3호
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    • pp.216-222
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    • 2015
  • 막증류(membrane distillation, MD)용 분리막의 장기 내구성능에 영향을 미치는 인자인 소수성 분리막의 젖음 현상에 대한 평가 지표로 사용되는 액체투과압력(liquid entry pressure, LEP) 측정 방법을 최적화하였다. PE (polyethylene) 분리막 및 PVDF (polyvinylidene di-fluoride) 중공사 분리막의 LEP를 측정하기 위하여 20 wt%의 고농도 염수를 제조하여 원수로 사용하고 투과수의 전도도를 모니터링하였다. PE와 PVDF 중공사 분리막의 신뢰성 있는 LEP 측정을 위해서는 5 min 이상의 holing time을 두고 주입 압력을 증가시켜야 하며, 증류수 수조의 물량대비 분리막의 면적비 또한 $10m^2/m^3$ 이상으로 부여되어야 함을 확인하였다.

Optimization of three small-scale solar membrane distillation desalination systems

  • Chang, Hsuan;Hung, Chen-Yu;Chang, Cheng-Liang;Cheng, Tung-Wen;Ho, Chii-Dong
    • Membrane and Water Treatment
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    • 제6권6호
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    • pp.451-476
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    • 2015
  • Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving the energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum-cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo steady state approach for equipment sizing and the dynamic optimization using overall system mathematical models. The s-SMDDS employing three MD configurations, including the air gap (AGMD), direct contact (DCMD) and vacuum (VMD) types, are optimized. The membrane area of each system is $11.5m^2$. The AGMD system operated for 500 kg/day water production rate gives the lowest unit cost of $5.92/m^3$. The performance ratio and recovery ratio are 0.85 and 4.07%, respectively. For the commercial membrane employed in this study, the increase of membrane mass transfer coefficient up to two times is beneficial for cost reduction and the reduction of membrane heat transfer coefficient only affects the cost of the DCMD system.

Trifocal versus Bifocal Diffractive Intraocular Lens Implantation after Cataract Surgery or Refractive Lens Exchange: a Meta-analysis

  • Yoon, Chang Ho;Shin, In-Soo;Kim, Mee Kum
    • Journal of Korean Medical Science
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    • 제33권44호
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    • pp.275.1-275.15
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    • 2018
  • Background: We compared the efficacy between trifocal and bifocal diffractive intraocular lens (IOL) implantation. Methods: Through PubMed, MEDLINE, EMBASE, and CENTRAL, we searched potentially relevant articles published from 1990 to 2018. Defocus curves, visual acuities (VAs) were measured as primary outcomes. Spectacle dependence, postoperative refraction, contrast sensitivity (CS), glare, and higher-order aberrations (HOAs) were measured as secondary outcomes. Effects were pooled using random-effects method. Results: We included 11 clinical trials, with a total of 787 eyes (395 subjects). The trifocal IOL group showed better binocular distance VA corrected with defocus levels of -0.5, -1.0, -1.5, and -2.5 diopter than the bifocal IOL group (All $P{\leq}0.004$). The trifocal IOL group showed better monocular uncorrected distance and intermediate VAs (mean difference [MD], -0.04 logarithm of the minimum angle of resolution [logMAR]; 95% confidence interval [CI], -0.07, -0.01; P = 0.006 and MD, -0.07 logMAR; 95% CI, -0.13, -0.01; P = 0.03, respectively). Postoperative refraction, glare, CS, and HOAs were not significantly different from each other. Conclusion: The overall findings indicate that trifocal diffractive IOL implantation is better than the bifocal diffractive IOL in intermediate VA, and provides similar or better in distance and near VAs without any major deterioration in the visual quality.