• Journal of Korean Society of Environmental Engineers
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• v.34 no.10
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• pp.664-670
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• 2012

A study on the in situ regeneration effect of commercial deactivated SCR catalyst which had been exposed to the off gas from the heavy oil fired power plant for a long time was carried out in a simulated in situ conditions by washing with distilled water and various acid solutions in a short time. The catalytic performance test of the regenerated SCR catalysts was carried out in the micro reactor with simulated off gas of the heavy oil fired power plant and all prepared catalysts were characterized by BET, Porosimeter, EDX (Energy Dispersive X-ray spectrometer) and ICP (Inductively Coupled Plasma) to investigate correlations between catalytic activity and surface characteristics of them. The characterization results of the regenerated catalysts showed that the specific surface area was restored 95% more than that of fresh catalyst. Under this study, the activity of the regenerated catalysts with acid solution (3~6 M) without using ultrasonic wave in a simulated in situ conditions was restored 90% more than that of the fresh catalyst. It was found that improved activity of regenerated catalyst was caused by removing the deactivating materials from the surface of the deactivated SCR catalyst through acid washing.

• Clean Technology
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• v.27 no.4
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• pp.325-331
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• 2021

In this study, bio-carbons were produced by activation process from unused biomass (Grade 3 wood pellet and spent coffee grounds) to determine the removal performance of formaldehyde and acetaldehyde. The activation experiments were conducted in a fixed bed reactor using CO₂ as an activation agent. The temperature of the activation reactor and input of CO₂ were 900 ℃ and 1 L min^-1 for all the experiments. The maximum BET surface area of about 788 m² g^-1 was obtained for bio-carbon produced from Grade 1 wood pellet, whereas about 544 m² g^-1 was achieved with bio-carbon produced from spent coffee grounds. In all the experiments, the bio-carbons produced were mainly found to have micro-porous nature. A lower ash amount in raw material was favored for the high surface area of bio-carbons. In the removal test of formaldehyde and acetaldehyde, the bio-carbon produced from spent coffee grounds showed excellent adsorption performance compared with woody biomass (Grade 1 wood pellet and Grade 3 wood pellet). In addition, the comparative experiment of commercial impregnated activated carbon and bio-carbon produced from spent coffee grounds was conducted. In terms of formaldehyde removal performance, the commercial impregnated bio-carbon was excellent, while bio-carbon produced from spent coffee grounds was excellent in acetaldehyde removal.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.369-371
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• 2006

반도체에 이온화 방사선을 조사시키면 소자 내부에서 전자-전공쌍(Electron-Hole Pair, EHP) 생성현상이 나타난나. 이 발성 전하는 방사선원에 따라 반영구적인 전원으로 활용이 가능하다. 본 논문에서는 반감기가 100여년인 Ni-63 베타 방사성 능위원소와 PN 접합형 반도체 소자를 사용한 방사선 전지를 개발하기 위한 연구의 일환으로 효율적인 방사광 변환 법과 전류 발생방법 및 전지회로 구현에 대해서 고찰하였다. 또한 Ni-63 방사선의 베타선 스펙트럼을 계산하고 이에 해당하는 광입력 특성에 대한 실리콘 PN 접합 다이오드의 반응특성을 태양광 시뮬레이션용 소프트웨어를 사용하여 검증하였다.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.825-828
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• 1998

경혈을 대상으로 인체를 진단하는 의료기기들은 경혈점에 미세한 직류전류를 인가하고, 이 점에서의 전기저항과 세포의 분극에 의해 반응하는 경락체계의 균형상태를 측정하여 인체를 종합적으로 진단한다. 따라서 전 과정이 정확한 경혈의 위치에서 이루어져야만 치료효과와 진단의 신뢰성이 보장된다. 그러나 대부분의 경락관련 치료기들이 정확한 혈위식별에 어려움이 있고 사용자의 전문적 숙련을 요구한다. 따라서 선행연구에서 일정한 주파수로 교호되는 자극패턴(SPAC) 방식을 사용하여 식별률을 높인 혈위식별기 DM96A-1를 개발하였다. DM96A-1은 단일전원이 양방향으로 교호되는 전류로 자극펄스를 출력하고 측정범위가 0.5∼50㎂인 전류메터와 레벨메터를 이용하여 혈위의 전류량을 표시한다. 이에 따라 방향전환 소자의 두 채널 제어신호가 교호되는 과도기에서 두 자극패턴의 중첩 도통에 의해서 누설전류가 발생하는 경우가 있으며 이를 제거하기 위하여 정밀한 조정을 필요로 하는 불편이 있었다. 따라서 이와 같은 단점들을 보완하여 신뢰성 있는 출력 파라메터를 얻을 수 있도록 마이크로프로세서 i80c196kc를 사용하여 DM96A-2를 재 설계하였으며 임상실험에 의하여 개선된 최적 파라메터의 타당성을 검증하였다.

• KSBB Journal
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• v.28 no.1
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• pp.31-35
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• 2013

In this work a $MABOOMS^{TM}$ has been employed to cultivate microorganisms and investigated the effects of culture medium components on cell growth. A 24-well microplate coated with 4-divided fluorescent sensing membranes was used to monitor the dissolved oxygen, pH and cell concentration during cultivations. Fluorescence intensity for dissolved oxygen or solution pH and reflectance for cell concentration was online monitored by using the $MABOOMS^{TM}$. The online monitoring results showed the effects of culture medium components on cell growth in cultivation processes very well.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.119-125
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• 2020

Transition metal dichalcogenides (TMDCs), two-dimensional atomic layered materials with direct bandgap in the range of 1.1-2.1 eV, have attracted a lot of research interest due to their high response to light and capability to build new types of artificial heterostructures. However, the large-area synthesis of high-quality and uniform TMDC films with vertical-stacked heterostructure still remains challenge. In this study, we have developed a metal-organic chemical vapor deposition (MOCVD) system for TMDCs and conducted a systematic study on the growth of single-layer TMDCs and their heterostructures. In particular, using a bubbler-type organometallic compound sources, the concentration and flow rate of each source can be precisely controlled to obtain uniformly single-layered MoS2 and WS2 films over the centimeter scale. In addition, the MoS2/WS2 vertical heterostructure was achieved by growing WS2 film directly on the MoS2 film, as confirmed by electron microscopy, UV-visible spectrophotometer, Raman spectroscopy, and photoluminescence spectroscopy.

• Clean Technology
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• v.27 no.4
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• pp.341-349
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• 2021

In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NO_X) and sulfur oxides (SO_X), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NO_X and SO_X, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NO_X and SO_X emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NO_X and SO_X. However, even in the NO_X and SO_X simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NO_X, SO_X simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NO_X and SO_X removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NO_X and SO_X are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NO_X and SO_X removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.

• Journal of the Korean Institute of Gas
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• v.14 no.1
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• pp.15-20
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• 2010

The interest on the utilization of landfill gases and biogases for energy production has been increasing due to environment concerns and global warming caused by burning fossil fuels, renewable nature of these gases. Using those synthesis gases to generate energy with engine encourages more efficient collection reducing emissions into the atmosphere and generates revenues for the operators. However the lower calorific value of synthesis gases than that of LPG or CNG affects the combustion stability and power output. Thus it becomes necessary to address disadvantages involved by studying synthesis gases in technological perspective. This paper discussed synthesis gas as a fuel for 60kW dual-fuel engine to produce power in an effective way. The methane diluted with $N_2$ was used as a fuel and developed ECU and injector driver facilitated the investigations with diesel fuel.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.13-19
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• 2000

Shear strengths of BGA solder joints on Cu pads were studied for Cu-containing Sn (0, 1.5, and 2.5 wt.% Cu) and Sn-40Pb (0 and 0.5wt.% Cu) solders, with emphasis on the roles of the Cu-Sn intermetallic layer thickness and the roughness of the interface between the intermetalic layer and solder. The shear strength test was performed for as-soldered solder joints with various soldering reaction times up to 4 min. The addition of Cu to the pure Sn solder results in an enhanced growth of the intermetallic layer whereas the effect of Cu addition to the Sn-40Pb solder is primarily on the reduction of the roughness of the intermetallic/solder interface. The critical thickness of the intermetallic layer for a maximum shear strength depends on the solder materials, which was measured to be ~ 2.3 $\mu\textrm{m}$ for Sn-Cu solders and ~ 1.2 $\mu\textrm{m}$ for Sn-Pb-Cu solders. The shear strength at the critical intermetallic layer thickness seems to increase as the intermetallic/solder interface becomes rougher. This is in accordance with the observation that the sheared fracture occurred initially within the solder tends to shift towards the intermetallic/solder interface as the intermetallic layer grows above the critical thickness.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.1237-1246
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• 2020

Recently, several cache side channel attacks have been proposed to extract secret information by exploiting design flaws of the microarchitecture. The Flush+Reload attack, one of the cache side channel attack, can be applied to malicious application attacks due to its properties of high resolution and low noise. In this paper, we proposed a detection system, which detects the cache-based attacks using the PCM(Performance Counter Monitor) for monitoring CPU cache activity. Especially, we observed the variation of each counter value of PCM in case of two kinds of attacks, Spectre attack and secret recovering attack during AES encryption. As a result, we found that four hardware counters were sensitive to cache side channel attacks. Our detector based on machine learning including SVM(Support Vector Machine), RF(Random Forest) and MLP(Multi Level Perceptron) can detect the cache side channel attacks with high detection accuracy.