• Journal of the Korean Society of Radiology
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• v.11 no.1
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• pp.55-61
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• 2017

There are no recommended test conditions for digital photography in Chest PA examinations. However, each company recommends shooting examinations of the high voltage applied to the previous analog examination. The condition that satisfies the value of 200 ~ 800 which is the recommended Exposure Index value recommended by Philips was selected, and the dose was evaluated by Monte Carlo simulation, and the SNR and CNR were compared. As a result, it was possible to reduce the effective dose up to 77% by controlling the tube voltage, tube current, and additional filter, not the conventional high voltage imaging method. Although there were some differences according to the test conditions, the image evaluation results were similar to the images. We will compare the exposure dose according to changes in tube voltage, tube current, and additional filter at the digital chest radiograph and evaluate the image quality of the image to propose optimal conditions.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.12-18
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• 1999

This research was undertaken to do the technical and economical feasibility study of membrane water treatment system. For the technical feasibility study, batch water treatment system using UF(ultrafiltration) was set up and several experiments were carried out. The performance of the UF membrane was tested in terms of turbidity. The experimental results showed that the UF membrane process produced less than 1 NTU water regardless of input water turbidity. For the economical feasibility study, the cost model was analyzed and programmed for simulation. Also costs of the membrane water treatment and the conventional treatment were evaluated. The simulation results showed that the unit production cost increased when design flow or permeate flow decreased. The production cost of membrane water treatment system was lower than that of the conventional system. Both technical and economical feasibility study showed that the UF membrane water purification system was a very competitive water purification process.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.429-436
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• 2008

Membrane system has been increasingly considered as a safe and cost-effective water treatment process especially in case of small scale water works. This research is a basis of membrane application in water works through a long period test with obtaining operation skills and evaluation of water quality and cost competitiveness. For the research, the UF membrane system was installed in small water treatment plant that uses river-bed water as raw water. The system was consisted of 2 stage membrane and operated in constant flow mode (Flux: 1.5, 1.0, 0.9, 0.6). In each different flux condition, TMP trends were showed better results at lower flux condition. And through the high flux condition test, it is certified that membrane system could deal with breakdown of one stage. Water quality of permeate was satisfied the water quality standards especially turbidity. To know what mainly causes fouling on membrane, the test by membrane with several cleaning agents and EDX analysis have done in lab. Through the tests, ferrous concentration in raw water, backwashing water and membrane surface etc. was high and it causes fouling inside and outside of membrane. So acid cleaning using organic acid such as oxalic acid is necessary in Chemical in Place (CIP). At the economical aspect the electrical cost of membrane system is higher than that of slow sand filtration but labor cost can be reduced by automation. However, the use of labor should be determined considering effectiveness and stability of operation. Because during the operation, there are several breakdown such as electrical shock by lightning, water drop in summer, etc.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.4
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• pp.371-375
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• 1988

Tubular ultrafiltration membranes were used to investigated mass transfer characteristics of waste cheese whey. The effects of bulk concentration and flow velocity on permeat flux, mass transfer coefficient and apparent rejection coefficient were measured. Mass transfer coefficient was increased linearly with increasing flow velocity, and following relationship between mass transfer coefficient(k) and linear velocity(u) was obtained. $k=0.87{\times}10^{-5}u^{1-1}$ It is interjecting to note that plots for all linear velocity tend to converge to the same point for zero permeating flux, and the maximum bulk concentration that can be achieved with cheese whey extracts was 38(w/v %). In general, membrane rejection coefficient increased with increasing flow velocity and the rejection coefficients of cheese whey solution and that of lactose in cheese whey solution were obtained $0.40{\sim}0.65$, $0.15{\sim}0.30$, respectively.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.8-11
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• 1996

전기투석은 역삼투압, 한외여과와 함께 가장 많이 이용되고 막공정 중의 하나이다. 전기투석은 다른 막공정과 같이 막의 선택성에 의한 분리조작이며 병렬식 배열에 의한 막의 이용이 가능하고 막오염 현상이 있으며 따라서 막-유체간의 접촉에 대한 제어가 필요하다. 전기투석은 운전목적에 따라 desalting electrodialysis(ED)와 water-splitting electrodiaiysis(WSED)로 구분할 수 있다. Desalting electrodialysis는 고전적 의미의 탈염을 위한 전기투석공정이며 WSED는 bipolar membrane을 이용하여 염을 산과 염기로 분리시키는 기능을 갖는 전기투석 공정을 말한다. WSED는 전기적으로 물을 분리한다는 의미로서 Electrohydrolysis로 불리기도 한다. WSED의 기본원리는 bipolar membrane의 양쪽면에서 수소이옹과 수산이온을 발생시켜 산 또는 염기용액으로 전달하고 bipolar membrane에 접하고 있는 양이온 또는 음이온 교환막에서는 각 용액의 전기적 중성을 유지하기 위해 대응하는 이온을 투과시키는 것이다. WSED는 염으로부터 산 염기제조 뿐만아니라 염의 형태로 생성되는 유기산, 아미노산 등 발효생성물의 회수 또는 acidification에 이용되고 있다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.110-112
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• 1998

1. 서론 : 분석화학의 중요한 과제중 하나 고효율(high efficiency)과 고해상도(high resolution)를 가지고서 혼합물에서 분자나 입자의 분리능을 개선하는 것과 낮은 수준의 농도에서 이런 분획들(fractions)을 정량화 하는 것이다. 현재의 추세는 분리하고자 하는 분자의 상한선을 증가시키는 것이 순수과학과 산업에서 중요하게 되었다. 이런 분리 기술의 응용은 거대분자(macromolecules)와 입자들(particles)인 cell fragments, plasmides, chromosomes, liposomes, synthetic polymers 등에 적용되고 있는데, 고전적인 분석방법으로는 한외여과, 원심분리, 크기배제 크로마토그래피 등이 있지만 시간이 걸리고 해상도와 효율에 제한이 있다.

• Membrane Journal
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• v.31 no.5
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• pp.315-326
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• 2021

Lithium ion battery (LIB) demands increase every year globally to reduce the burden on fossil fuels. LIBs are used in electric vehicles, stationary storage systems and various other applications. Lithium is available in seawater, salt lakes, and brines and its extraction using environmentally friendly and inexpensive methods will greatly relieve the pressure in lithium mining. Membrane separation processes, mainly nanofiltration (NF), is an effective way for the separation of lithium metal from solutions. Electrodialysis and electrolysis are other separation processes used for lithium separation. The process of reverse osmosis (RO) is already a well-established method for the desalination of seawater; therefore, modifying RO membranes to target lithium metals is an excellent alternative method in which the only bottleneck is the interfering presence of other metal elements in the solution. Selectively removing lithium by finding or developing suitable NF membranes can be challenging, but it is nonetheless an exciting area of research. This review discusses in detail about lithium recovery via nanofiltration, electrodialysis, electrolysis and other processes.

• Membrane Journal
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• v.33 no.3
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• pp.87-93
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• 2023

Electrodialysis (ED) is essential in separating ions through an ion exchange membrane. The disposal of brine generated from seawater desalination is a primary environmental concern, and its recycling through membrane separation technology is highly efficient. Alkali is produced by several chemical industries such as leather, electroplating, dyeing, and smelting, etc. A high concentration of alkali in the waste needs treatment before releasing into the environment as it is highly corrosive and has a chemical oxygen demand (COD) value. The concentration of calcium and magnesium is almost double in brine and is the perfect candidate for carbon dioxide adsorption, a major environmental pollutant. Sodium hydroxide is essential for the metal carbonation process which, is easily produced by the bipolar membrane electrodialysis process. Various strategies are available for its recovery, like reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and ED. This review discusses the ED process by ion exchange membrane for alkali recovery are discussed.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.237-245
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• 2017

This study was aimed at investigating effluent water quality and proposing reuse possibilities for 12 sewage treatment plants discharged more than $5,000m^3/day$ in order to recycle the sewage treatment plant effluent of Jeollabuk-do effectively. Additionally, a laboratory scale test for reprocessing water discharge was performed. Categories of reclaimed sewage water reuse were divided into 7 topics and analyzed a total of 28 items including 16 heavy metals based on water quality standard. As a results, color, BOD, TN, chloride and Electrical Conductivity (EC) exceeded reused water quality standard. In particular, color and TN exceeded in 8 and 5 sewage treatment plants, respectively. The value of chloride and EC were high in sewage treatment plants including the food and industrial wastewater. At 4 sewage treatment plants were possible to reuse without re-treatment. The laboratory scale test was conducted to SandFilter (SF)-Granular Activated Carbon (GAC)-MicroFiltraion (MF)-Reverse Osmosis (RO). Both the removal efficiencies and economic feasibility of total E. coli., color and Suspended Solid (SS) suited in case using the SF-GAC treatment method. The removal of chloride and EC had little effect in the case of SF-GAC-MF system, but RO showed over 90% of removal efficiency. After using SF-GAC process only, the concentration of $UV_{254}$ decreased sharply from 0.3651 /cm to 0.0306 /cm and it showed over 92% of removal efficiency rate. In conclusion, for the effective reuse of sewage discharged water, water quality and the surrounding terrain of treatment plants should be all taken into account. If it needed for the reprocessing, both the selection for treatment and economic combination treatment methods will have to be considered.

• Childhood Kidney Diseases
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• v.14 no.2
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• pp.111-119
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• 2010

The maintenance of the osmolality of body fluids within a very narrow physiologic range is possible by water balance mechanisms that control the intake and excretion of water. Main factors of this process are the thirst and antidiuretic hormon arginine vasopressin (AVP), secretion regulated by osmoreceptors in the hypothalamus. Body water is the primary determinant of the osmolality of the extracellular fluid (ECF), disorders of body water homeostasis can be divided into hypo-osmolar disorders, in which there is an excess of body water relative to body solute, and hyperosmolar disorders, in which there is a deficiency of body water relative to body solute. The sodium is the predominant cation in ECF and the volume of ECF is directly proportional to the content of sodium in the body. Disorders of sodium balance, therefore, may be viewed as disorders of ECF volume. This reviews addresses the regulatory mechanisms underlying water and sodium metabolism, the two major determinants of body fluid homeostasis for a good understanding of the pathophysiology and proper management of disorders with disruption of water and sodium balance.