• Clean Technology
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• v.18 no.1
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• pp.69-75
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• 2012

In this study, we executed an environmental impact assessment about recycling of ITO (Indium Tin Oxide), used for touch panel. ITO is mainly used to make transparent conductive coatings for touch and flat screen LCD (Liquid Crystal Display), ELD (Emitting Light Device), PDP (Plasma Display Panel). This demand is increasing little by little. but form current status, ITO is discarded than recycling. It is important to recycling ITO for national strategies about resource conservation, and reduce environmental burden. Also Landfill or incineration of ITO cloud be harmful to the human health in the long-term. Material Life Cycle Assessment method (MLCA) was conducted for comparison landfill and recycling of ITO. MLCA would provide more information for environmental issues and potential environmental impacts of ITO. The study includes two scenarios, the basic scenario is recycling of ITO (10, 20, 30%) and the other scenario is landfill of ITO. In addition, amount of carbon dioxide and energy were calculated.

• Analytical Science and Technology
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• v.35 no.6
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• pp.249-255
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• 2022

In this study, a new method for the analysis of high-purity nitrogen was developed. A gas chromatography-flame ionization detector (GC-FID) was used for purity analysis. Certified reference materials (CRMs) at a level of 3 µmol/mol of carbon monoxide (CO), carbon dioxide (CO₂), and methane (CH₄), which may exist in high-purity nitrogen, were prepared using the gravimetric method, and these CRMs were used for purity analysis. In this new method, ultra-high-purity and high-purity nitrogen were used as carrier gases. The impurities in high-purity nitrogen were quantitatively analyzed by comparing the differences in the area values of the GC chromatograms of the prepared CRMs. We purchased liquid nitrogen and three bottles of nitrogen gas, which were produced by three different manufacturers, using high-purity nitrogen. Furthermore, to validate the developed purity analysis method, the fraction of impurities in high-purity nitrogen was compared with the results of the typical purity analysis method. The comparison results were consistent within the expanded uncertainties (k = 2).

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.485-494
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• 2000

According to the worldwide interest in controlling $CO_2$ which contributes to green house effect. new techniques of reducing $CO_2$ are under development. We have developed new technique for reducing $CO_2$. In low $CO_2$ concentration. the chemical absorption method is useful. In this study. the kinetics of the reaction between $CO_2$ and the sterically hindered amine solution with piperazine. have been investigated from measurements of the rate of absorption of $CO_2$ in the stirred vessel that has a horizontal liquid-gas interface, in the temperature range $30{\sim}70^{\circ}C$. The experiments were carried out in the range 10.130~20.260 kPa of partial pressure of $CO_2$, and in aqueous $2.0kmol/m^3$ AMP solution with $0{\sim}0.4kmol/m^3$ piperazine The experimental results are as follows: 1) The absorption rate of $CO_2$ into aqueous AMP + piperazine solution is gett ng faster than that of aqueous AMP absorbents with temperature. Because the activation energy of piperazine 57.147 kJ/mol is higher than that of AMP 41.7kJ/mol. therefore the effect of piperazine on absorption rate increases with temperature. 2) Compared with aqueous AMP solution. the absorption rate of $CO_2$ into AMP + piperazine solution increases from 6.33% at $30^{\circ}C$ to 12% at $70^{\circ}C$, so AMP + piperazine solution is thought to be a better than AMP solution, 3) The reaction rate constants of piprazine in aqueous AMP solution with $CO_2$ have been determined as 217.21, 420.46, 707.00 and $3162.167m^3/kmol{\cdot}s$ respectively at 30, 40, 50 and $70^{\circ}C$ but these results are higher than those of Xu which were 186.7. 367.32. 693.01. $2207.65m^3/kmol{\cdot}s$ at 30, 40, 55, $70^{\circ}C$in aqueous MDEA solution. So the regression analysis of the data has led to the following equation In $k_p$ =28.324-6934.7/T.

• Economic and Environmental Geology
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• v.53 no.1
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• pp.1-9
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• 2020

Magnesium silicate minerals such as serpentine [Mg₃Si₂O₅(OH)₄] have a high potential for the sequestration of CO₂; thus, their reactivity toward dissolution under CO₂-free and CO₂-containing conditions in acidic solvents is a critical process with respect to their carbonation reactions. To examine the carbonation efficiency and dissolution mechanism of serpentine, hydrothermal treatment was performed to the starting material via a modified direct aqueous carbonation process at 100 and 150℃. The serpentine dissolution experiments were conducted in H₂SO₄ solution with concentration range of 0.3-1 M and at a CO₂ partial pressure of 3 MPa. The initial pH of the solution was adjusted to 13 for the carbonation process. Under CO₂-free and CO₂-containing conditions, the carbonation efficiency increased in proportion to the concentration of H₂SO₄ and the reaction temperature. The leaching rate under CO₂-containing conditions was higher than that under CO₂-free conditions. This suggests that shows the presence of CO₂ affects the carbonation reaction. The leaching and carbonation efficiencies at 150℃ in 1 M H₂SO₄ solution under CO₂-containing conditions were 85 and 84%, respectively. The dissolution rate of Mg was higher than that of Si, such that the Mg : Si ratio of the reacted serpentine decreased from the inner part (approximately 1.5) to the outer part (less than 0.1). The resultant silica-rich layer of the reaction product ultimately changed through the Mg-depleted skeletal phase and the pseudo-serpentine phase to the amorphous silica phase. A passivating silica layer was not observed on the outer surface of the reacted serpentine.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.505-514
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• 2009

Aqueous potassium salt of serine was proposed as an alternative $CO_2$ absorbent to monoethanolamine (MEA) and its $CO_2$ absorption characteristics were studied. The experiment has been conducted using screening test equipment with NDIR type gas analyzer and vapor-liquid equilibrium apparatus. $CO_2$ absorption/desorption rate and net amount of $CO_2$ absorbed in cyclic process are the criteria to assess the $CO_2$ absorption characteristics in this study. Effective $CO_2$ loading of potassium salt of serine and MEA are 0.425 and 0.230 respectively. Cyclic capacities are 0.354 and 0.298 for potassium salt of serine and MEA. The absorption rate of the potassium serinate decreased sharply at $CO_2$ loading is 0.1 and were maintained approximately at half of MEA. To enhance the absorption rate of aqueous potassium salt of serine, small quantities of rate promoters, namely piperazine and tetraethylenepentamine were blended, so that rich $CO_2$ loading were increased by 13.7% and 18.7% respectively. The rich $CO_2$ loading of potassium salt of serine was 29.2% and 35.0% higher than those of aqueous sodium and lithium salt of serine, respectively. The absorption rate of potassium salt of valine and isoleucine which have similar molecular structures to serine were lower than that of serine because of the presence of bulky side group. Precipitation phenomena during $CO_2$ absorption were discussed by the aid of literatures.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.51-52
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• 2000

생물공정의 운전에 있어서 적절한 공정변수가 부족한 경우가 많다. 이것은 멸균과정을 견딜 수 있는 신뢰성 높은 센서가 부족하기 때문이다[1]. 생물공정에 주로 사용되는 센서로서는 온도, pH, D.O., rpm, viscosoty 등이 있으나 이 센서들은 배양액의 물리적 혹은 화학적 상태를 측정할 수 있는 경우가 대부분이다[2]. 미생물의 대사활동과 관련이 있는 공정 변수로는 배출가스의 성분을 측정하여 얻을 수 있는 Oxygen uptake rate, Carbon dioxide evolution rate 및 Respiratory quotient가 있으며 현재 생물공정의 운전에 사용되고 있다[3]. 그러나 반복적인 센서의 보정과 연결관의 잦은 청소 및 보수를 필요로 하여 제한적으로 사용되고있는 실정이다. 자동화된 습식분석장치, Gas chromatograph, High Performace Liquid Chromatograph 혹은 Mass spectrophtometry 등을 온라인 샘플 처리장치와 연결하여 발효조의 배양액의 성분을 온라인으로 분석하고 공정의 운전에 응용하는 사례가 많이 발표되었다[4-6]. 고가의 장비 및 운전의 번거러움이나 추가적인 인력이 필요하므로 역시 특별한 경우에만 사용되고 있다. 이외에도 여러 종류의 온라인 센서 및 바이오 센서등이 개발되어 사용되고 있으나 역시 그 사용범위는 특수한 영역에 한정되어있다. 이와 같이 새로운 센서를 개발하여 공정변수를 측정하려는 시도중의 하나가 소프트웨어 센서의 개발이다. 이 것은 공정상에서 발생하는 1차 공정변수를 이용하여 배양액의 상태 혹은 2차적인 공정 변수를 추측해내는 것이다. 대부분의 경우 기존의 공정 변수를 사용하므로 추가적인 비용이 들지 않고 소프트웨어의 형태로 구현되므로 센서의 보정과 설치 및 유지관리의 노력이 매우 적은 장점이 있다. 본 연구에서는 생물공정에서 자동제어 과정에서 발생하는 여러 가지 공정상의 제어 신호로부터 새로운 공정 변수를 얻어내고자 시도하였다. 대부분의 생물공정에서는 pH의 자동제어가 필수적인데 자동제어 과정에서 발생하는 pH 제어 신호 및 pH의 변화 응답신호를 이용하여 배지의 완충용량의 변화와 알칼리의 소비속도를 온라인으로 측정할 수 있었다. 여기에 인공지능망을 설계하여 균체의 량을 온라인으로 추정하는 방법을 개발하였다 [7].산업용 발효조의 운전 온도는 주로 냉각수의 단속적인 공급에 의하여 항상 일정하게 조절된다. 따라서 냉각수의 냉각량을 측정하면 미생물의 배양시 발생하는 대사열량을 측정할 수 있게 된다. 본 연구에서는 실험실의 발효조를 냉각수의 단속적인 공급에 의하여 자동온도 조절이 되도록 개조하고 여기에 냉각수의 유출입 지점에 온도센서를 부착하여 냉각수의 온도를 측정하고 냉각수의 공급량과 대기의 온도 등을 측정하여 대사열의 발생을 추정할 수 있었다. 동시에 이를 이용하여 유가배양시 기질을 공급하는 공정변수로 사용하였다 [8]. 생물학적인 폐수처리장치인 활성 슬러지법에서 미생물의 활성을 측정하는 방법은 아직 그다지 개발되어있지 않다. 본 연구에서는 슬러지의 주 구성원이 미생물인 점에 착안하여 침전시 슬러지층과 상등액의 온도차를 측정하여 대사열량의 발생량을 측정하고 슬러지의 활성을 측정할 수 있는 방법을 개발하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4721-4726
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• 2010

The performance characteristics of water-chilling heat pump using CO2 for the control of inverter frequency was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter flow type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2.4m length. The experimental results summarize as the following: for constant inlet temperature of evaporator and gas cooler, as mass flow rate, compression ratio and discharge pressure increases with the inverter frequency. And heating capacity and compressor work increases, but coefficient of performance(COP) decreases with the inverter frequency of compressor. As inlet temperature of secondary fluid in the evaporator increases from $15^{\circ}C$ to $25^{\circ}C$, compression ratio and compressor work decreases, but mass flow rate, heating capacity and COP increases with the inverter frequency of compressor. The above tendency is similar with performance variation with respect to the variation of inverter frequency in the conventional vapor compression refrigeration cycle.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.160-163
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• 2008

$CO_2$ ocean sequestration is being considered as a way to earn a frame of time to change other industrial life pattern to overcome the global warming crisis. The method is to dilute the captured $CO_2$ into ocean by ejecting the liquefied $CO_2$ through nozzles. The main issue of such method is the effectiveness and safety, and in both problems the rising speed of those LCO2 droplet is the key parameter. In this paper, the rising speed of LCO2 droplets is numerically studied including the effect of the surfactant which can be residing along the density interface of the droplets. A front tracking method with a simple surface tension model is developed and the rising speed of the droplets is carefully investigated with varying the various parameters. It is demonstrated that the variable surface tension can change the deformation of the droplet, the flow near the interface, and the rising speed.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.57-63
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• 2015

Absorption characteristics of 2-methylpiperidine (2MPD), 3-methylpiperidine (3MPD) and 4-methylpiperidine (4MPD) absorbents were studied by a vapor-liquid equilibrium (VLE) apparatus and a differential reaction calorimeter (DRC). Using a VLE apparatus, the $CO_2$ loading capacity of each absorbent was estimated. After reaching the absorption equilibrium, nuclear magnetic resonance spectroscopy (NMR) had been conducted to characterize the species distribution of the ($H_2O$-piperidine-$CO_2$) system. Using a DRC, the reaction of heat was confirmed in accordance with the absorption capacity. The unique characteristics of 2MPD, 3MPD and 4MPD absorbents appeared by the position of methyl group. The 2MPD possessing the methyl group at the ortho position showed its hindrance effect during the absorption process; however, piperidine derivatives possessing the meta position and para position did not show its characteristics in $H_2O$-piperidine-$CO_2$ system.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.241-246
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• 2008

Increase of $CO_2$ by using fossil fuels makes mainly global warming and the international efforts to reduce the $CO_2$ emission is being promoted. Absorption process using aqueous alkanolamine solution to remove acid components in the mixed gases has been used commercially. This method was used to remove $CO_2$ in the flue gas in recent years. $CO_2$ Absorption characteristics of several aqueous alkanolamine solutions such as MEA, DEA and AMP was studied by measuring vapor-liquid-equilibrium(VLE) and absorption velocity in this study. VLE measuring equipment, shell and reactor type, was used to acquire VLE data, equilibrium $CO_2$ pressure(${P_{CO_2}}^*$) and time at each pulse gas input. We also acquired the $CO_2$ absorption velocity by measuring the time to arrive the VLE at $40{\sim}80^{\circ}C$ and first gas input. The $CO_2$ absorption capacity of MEA 10wt% solution was higher than two alkanolamine solutions at $40^{\circ}C$ and the equilibrium $CO_2$ loading was 0.5. Absorption capacity was excellent as follows; AMP>DEA>MEA. But absorption velocity was fast as follows; MEA>AMP>DEA. Though good absorbent was considered by many variables, absorption velocity and capacity was more important factor.