• Proceedings of the Membrane Society of Korea Conference
• /
• 1996.09a
• /
• pp.121-145
• /
• 1996

Due to more stringent regulations in drinking water, membrane separation has been playing an increasingly important role. Seawater desalination by reverse osmosis is a typical example and has been used world-wide. Although the existing technology based on coagulation and media filtration is well established and reliable technology, with the advance of industrial and agricultural activities it is difficult for this technology to remove contaminants such as nitrate and synthetic organic chemicals. To meet the drinking water standards and produce higher quality water, several membrane filtration research programs have been initiated which include Japanese MAC21 and New MAC21 projects. In this paper, potable water application of reverse osmosis (RO) and nanofiltration(NF) and their case histories will be explained in more detail.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2019.06a
• /
• pp.125-126
• /
• 2019

현재 상업적으로 널리 쓰이는 CCTV 용 카메라는 충분한 광량이 보장된 환경에서는 가시영역 영상을, 저조도 환경에서는 적외선 영상을 획득한다. 적외선 영상은 색채정보를 갖고 있지 않아 객체의 색채 정보를 이용하여야 하는 응용에 활용하기 어렵다. 본 논문에서는 ND 필터를 사용하여 가시광선 및 근적외선 영역의 영상정보를 분리하여 취득하는 가능성에 대한 연구를 하였다. 먼저 카메라 내부의 Hot Mirror 필터를 제거하여 가시영역 및 근적외선 신호 모두가 카메라에 들어오도록 한 후 ND 필터를 사용하여 영상을 취득한 후, 본 논문에서 제안하는 분리방식을 사용하여 가시영역 및 근적외선 영역으로 분리하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2022.06a
• /
• pp.851-853
• /
• 2022

인공지능을 활용한 다양한 딥러닝 기술의 보급과 상용화로 오디오 음성 인식 분야에서도 음성 인식의 정확도를 높이기 위한 다양한 연구가 진행되고 있다. 최근 STT 를 위한 음성 인식 엔진은 딥러닝 기술을 기반으로 과거에 비해 높은 정확도를 보이고 있다. 하지만 예능 프로그램, 드라마, 스포츠 방송 등과 같이 비음성 신호와 음성 신호가 함께 녹음되는 오디오의 경우 음성 인식 정확도가 크게 낮아지는 문제가 발생한다. 이에 본 연구에서는 다양한 장르의 오디오를 음성과 음악을 분리하는 딥러닝 모델을 활용하여 음성 신호와 비음성 신호로 분리하는 방법을 제시하고, STT 결과를 분석하여 음성 인식의 정확도를 높이기 위한 연구 방향을 제시한다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.3
• /
• pp.259-266
• /
• 2013

An automated cell tracking system is used to automatically analyze and track the changes in cell behavior in time-lapse cell images acquired using a microscope with a cell culture. Clustering is the partial overlapping of neighboring cells in the process of cell change. Separating clusters into individual cells is very important for cell tracking. In this study, we proposed an algorithm for separating clusters by using ellipse fitting based on a direct least square method. We extracted the contours of clusters, divided them into line segments, and then produced their fitted ellipses using a direct least square method for each line segment. All of the fitted ellipses could be used to separate their corresponding clusters. In experiments, our algorithm separated clusters with average precisions of 91% for two overlapping cells, 84% for three overlapping cells, and about 73% for four overlapping cells.

• Journal of environmental and Sanitary engineering
• /
• v.14 no.1
• /
• pp.31-41
• /
• 1999

Several new ion exchange resins have been synthesized from chloromethyl styrene-1, 4-di-vinylbenzene with 1%, 2%, 5% and 10%-crosslinking and macrocyclic ligands of cryptand type by interpolymerization method. The adsorption characteristics and the pH, time, solvents and concentration dependence of the adsorption of metal ions by this resin were studied. The correlation between the separation characteristics of uranium and transition metal on the resins and the stability constants of complexes with macrocyclic ligands have been examined. The resins were very stable in both acidic and basic media and had good resistance to heat at $280^{\circ}C$. The $UO_2^{2+}$ aqueous solution was not adsorbed on the resins below pH 3.0, but the power of adsorption of $UO_2^{2+}$ increased rapidly above pH 4.0. The optimum equilibrium time for adsorption of metallic ions was twenty minutes and adsorptive power decreased in proportion to crosslinking size of the resins and order of dielectric constants of solvents used and the selective sequence for metal cations is in the order of $UO_2^{2+}$, $Cu^{2+}$ and $Ce^{3+}$ .

• Korean Chemical Engineering Research
• /
• v.48 no.1
• /
• pp.1-9
• /
• 2010

Since carbon dioxide, $CO_2$, was revealed as a major greenhouse gas, techniques for its separation, capture, and storage have received increasing interest in recent years. Aqueous amines are the most widely accepted $CO_2$ absorbents, but they cause the problems such as high regeneration energy, thermal degradation, and loss of absorbents due to their volatility. Ionic liquids having high thermal stability, extremely low vapor pressure, and capability of selectively absorbing specific gases have been proposed as new $CO_2$ capturing solvents which may potentially replace aqueous amines. By reviewing the ionic liquids having capability to absorb $CO_2$ reported in previous papers, we seek to develop a comprehensive understanding on the factors that influence the $CO_2$ solubility in ionic liquids such as their structures, absorption temperature, pressure, water content, etc., and to estimate the potential of ionic liquids as $CO_2$ separating media.

• KSBB Journal
• /
• v.16 no.6
• /
• pp.533-537
• /
• 2001

${\alpha}$-lactalbumin and ${\beta}$-lactoglobulin in whey proteins were separated by high performance membrane chromatography (HPMC). The separation mechanism involved anion-exchange, and the stationary phase was anion CIM (Convective Interaction Media) DEAE, QA disk and cation exchanger SO$_3$(16${\times}$3 mm). Two types of mobile phase were used, buffer A (20 mM Tris-HCI, pH 7.3) and buffer B(buffer A + 1 M NaCl), As the amount of NaCl dissolved in buffer linearly increased, which enabled a gradient elution mode. The optimum mobile phase and operating condition (Buffer A/Buffer B = 100/0 - 30/70 vol%, gradient time 1 min, 30/70 - 10/90 vol.%, gradient time 2 min) were experimentally determined. In this experimental condition, ${\alpha}$-lacta1bumin, ${\beta}$-lactoglobulin were separated within 5 min at a mobile phase flow rate of 4 mL/min.

• Membrane Journal
• /
• v.29 no.2
• /
• pp.67-79
• /
• 2019

High purity propylene (propene) is an octane-enhancing chemical and also feedstock to industrially important chemicals. Purification of propylene from propane mixture is technologically and financially challenging because of their close boiling points. ZIF-8 membrane has been increasingly researched due to its great potential to separate propylene from propane effectively by molecular sieving. The increasing interest in ZIF-8 membranes lies in the so called "gate opening" effect. The gate opening effect enlarges the membrane pores and preferentially allows propylene to permeate through the membrane pores, while retaining the larger and heavier propane molecules in the feed stream in order to effect high propylene separation from propylene/propane mixture. In this paper, the widely accepted methods of ZIF-8 membrane preparation and parameters affecting propylene permeation and selectivity in ZIF-8 membrane are identified and reviewed.

• Korean Chemical Engineering Research
• /
• v.57 no.2
• /
• pp.149-163
• /
• 2019

Under non-uniform electric field, a directional force along the electric field gradient is applied to matter having permanent or induced dipoles. The transport of particles by the directional force is called dielectrophoresis (DEP). Since the strength and direction of the DEP force depend on parameters, such as permittivity and conductivity of particles and surrounding media, and frequency of the applied AC electric field, particle can be precisely manipulated by controlling the parameters. Moreover, unlike electrophoresis, DEP can be applied to any particles where dipole is effectively induced by electric field. Such a DEP technique has been used in various fields, ranging from microfluidic engineering to biosensor and microchip research. This paper first describes the fundamentals of DEP, and discusses representative microelectrode designs used for DEP study. Then, exemplary applications of DEP, such as separation, capture and self-assembly of particles, are introduced.

• Korean Chemical Engineering Research
• /
• v.50 no.2
• /
• pp.317-327
• /
• 2012

The average specific cake resistance, the most important indicator for cake filtration and solid-liquid separation, is measured by filtration experiment. But the exact value is difficult to measure because of the other influences such as sedimentation during filtration. This study, a little more stable method named filtration-permeation is proposed for measuring average specific cake resistance. The filtration-permeation is composed of permeation of particle eliminated water through pre-formed cake by filtration. Using 1 wt% calcium carbonate suspension, the filtration-permeation experiments were performed for 8 kinds of filter media at the conditions of 0.5 atm and 0.2 atm, 1 and 3 sheets of filter media. At each specific condition, three to five times filtration-permeation were accomplished. As a result, stable permeation speed is measured. According to this experimental result, the characteristics of permeation and the effect of sedimentation are analyzed with Ruth's equation. The one way analysis of variance (one way ANOVA) is applied to the average specific cake resistances of filtration and permeation obtained with the selected three kinds of filter media. The average specific cake resistances between 0.5 atm and 0.2 atm by filtration do not distinguished, but those by permeation is perfectly distinguished. The experimental results during permeation have a very narrow distribution than that measured during filtration. The analysis of filtration experiments, it was verified that the resistance of filter medium by traditional method is of no significance. Finally, the migration of small particles through the medium composed of fiber glass at low pressure was studied.