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Youngmin Cho,Yiseul Park,Wonyong Choi 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.3
The sensitized dechlorination of CCl₄ in water was successfully demonstrated in the presence of nonionic surfactants (Brij-35) and ruthenium bipyridyl complexes [RuⅡ(bpy)₃] under visible light illumination (λ > 420 nm). The ruthenium complex plays the role of a visible light sensitizer for this reductive conversion process, which is excited by absorbing visible light and subsequently transfers an electron to CCl₄. The photoinduced electron transfers from the excited sensitizer to CCl₄ take place only in the presence of the surfactant, which concentrates both reactants within a micelle. The ruthenium sensitizer should be oxidized after transferring an electron to CCl₄, but immediately regenerated by abstracting an electron from surrounding surfactant molecules. As a result, the ruthenium sensitizer acts as a photocatalyst with producing chlorides far above the stoichiometric concentration of the added sensitizer. The dechlorination rate was significantly reduced in the presence of dissolved oxygen, because the excited sensitizer is quenched by O₂. With increasing each concentration of the surfactant, sensitizer, or CCl₄, the corresponding CCl₄ dechlorination rate progressively increased, to reach a saturation at the concentration of 4.0 g/L (surfactant), 5 μM (sensitizer), or 30 mM (CCl₄), respectively. The visible light activity was strongly dependent on the kind of surfactants as well.
Recovery of Lactic Acid by Reactive Dividing Wall Column
Youngmin Cho,Bokyung Kim,Dongpil Kim,Myungwan Han 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Lactic acid is widely used in the food, chemical and pharmaceutical industries, and there is an increasing demand for Lactic acid as the raw material of poly lactic acid (PLA), which is a biodegradable polymer. Lactic acid production has been changing over from production by synthesis to production by fermentation, since the fermentation process is more nature friendly and economic. However, the fermentation method generates excess water and impurities with high boilers. The presence of high boilers and non volatility of lactic acid makes the separation of lactic acid very difficult job. Also, the purification-separation process requires the many investment costs and energy costs. The separation method that uses the reaction was proposed in order to overcome these problems. Esterification of lactic acid with methanol followed by hydrolysis of the separated methyl acetate was proposed as a technique to overcome these difficulties. Reactive distillation concept was also introduced for the process, giving higher selectivity and yield compared to the convention method [1]. Recently, the process consisting of evaporator, two-phase CSTR, a reactive distillation column, and distillation column was proposed for the purification of lactic acid by Kumar et al. [2-3]. We introduce a new highly integrated process, reactive diving wall column, to reduce the capital and energy cost for producing a pure lactic acid. The reactive dividing wall column combines reactive distillation and dividing wall column. The dividing wall column provides higher thermodynamic efficiency than conventional distillation sequences. We compared capital and energy cost required for the purification of lactic acid the between the proposed process and the process of Kumar et al. [2-3] and examined the effect of major process variables on the process performance.
Youngmin Kim,Junsoo Lee,Yongbeom Cho,Won Jae Lee,Seongjae Cho 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.2
Recently, active efforts are being made for future Si CMOS technology by various researches on emerging devices and materials. Capability of low power consumption becomes increasingly important criterion for advanced logic devices in extending the Si CMOS. In this work, a junctionless field-effect transistor (JLFET) with ultra-thin poly-Si (UTP) channel is designed aiming the sub-10-nm technology for low-power (LP) applications. A comparative study by device simulations has been performed for the devices with crystalline and polycrystalline Si channels, respectively, in order to demonstrate that the difference in their performances becomes smaller and eventually disappears as the 10-nm regime is reached. The UTP JLFET would be one of the strongest candidates for advanced logic technology, with various virtues of high-speed operation, low power consumption, and low-thermal-budget process integration.
조영민(Youngmin Cho),윤영관(Youngkwan Yoon),최진식(Jin-Sik Choi),박덕신(Duck-Shin Park),정우성(Woo-Sung Jung),권순박(Soon-Bark Kwon) 한국철도학회 2012 한국철도학회 학술발표대회논문집 Vol.2012 No.5
최근 수년간 기후변화에 따른 이상 기후현상이 나타나는 경우가 증가하고 있다. 특히 동절기의 이상저온 현상 및 혹한은 승객의 열적 쾌적성을 크게 저하할 우려가 있다. 이에 본 연구에서는 철도차량 실대형 환경챔버를 이용하여 저온의 외기온도 조건에서 철도차량의 난방장치를 가동할 때 객실 내부의 온도변화 및 분포를 알아보고, 이를 통해 외기온도의 하강에 따른 객실의 온열 쾌적감 저하를 최소화 하는 방안을 알아보고자 하였다. Abnormal climate is more frequently reported nowadays. Especially, abnormal low temperature and extreme coldness in winter season may cause the thermal discomfort of passengers. In this study, the effect of ambient temperature on cabin temperature change upon the operation of heating system in passenger car was studied by using a real-scale environmental chamber for passenger cabin. Based on the obtained result, the way to minimize the decrease of passengers' thermal comfort was suggested.
ε-다중목적 진화연산을 이용한 DNA Microarray Probe 설계
조영민(Youngmin Cho),신수용(Soo-Yong Shin),이인희(In-Hee Lee),장병탁(Byoung-Tak Zhang) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.1
최근의 생물학적인 연구에 DNA microarray가 널리 쓰이고 있기 때문에, 이러한 DNA microarray를 구성하는데 필요한 probe design 작업의 중요성이 점차 커져가고 있다. 이 논문에서는 probe design 문제를 thermodynamic fitness function이 2개인 multi-objective optimization 작업으로 변환한 뒤, ε-multiobjective evolutionary algorithm을 이용하여 probe set을 찾는다. 또한, probe 탐색공간의 크기를 줄이기 위하여 각 DNA sequence의 primer 영역을 찾는 작업을 진행하며, 사용자가 직접 프로그램을 테스트할 수 있는 웹사이트를 제공한다. 실험 대상으로는 mycoides를 선택하였으며, 이 논문에서 제안된 방법을 사용하여 성공적으로 probe set을 발견할 수 있었다.
조영민(Youngmin Cho),이지윤(Ji-Yun Lee),최진식(Jin-Shik Choi),권순박(Soon-Bark Kwon),박덕신(Duck-Shin Park),김희만(Hee-Man Kim) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
People spend approximately 80 ~ 90 % of their time in various kinds of indoor spaces. And in metropolitan area most people spend more than 1 hour in public transportation everyday. For this reason people's interest in the indoor air quality is drastically increasing. Among various indoor air pollutants CO2 is one of the most severe environmental concerns. Ventilation is commonly used to keep low CO2 concentration in the passenger cabin. However ventilation may worse the indoor air quality problem in case of subway because the tunnel is seriously polluted by particulate matters. In this study an alternative way to remove CO2 was suggested. The adsorption of CO2 by CO2 adsorbent was studied. Zeolite modified with base was prepared and CO2 removal performance was tested in 4m3 and 24m3 environmental chambers. It was found that CO2 adsorbent could effectively remove CO2 in the chambers.
조영민(Youngmin Cho),김기환(Gi-Hwan Kim),박덕신(Duck-Shin Park),권순박(Soon-Bark Kwon),정우성(Woo-Sung Jung) 한국산학기술학회 2015 한국산학기술학회 학술대회 Vol.2015 No.1
겨울철에 도시철도를 이용하는 승객들은 객실 내부 온도에 만족하기 어려운데, 그 이유는 객실 내부의 온도가 위치에 따라 다르기 때문이다. 특히 잦은 출입문 개폐와 난방기의 가동은 객실 내부의 온도 차이를 크게 만드는 원인이 되고 있다. 일반적으로 객실 내부의 온도 분포를 보면 같은 높이의 동일한 평면에서는 거의 비슷한 온도를 나타내지만, 높이에 따라서는 온도가 크게 달라진다. 이에 본 연구에서는 객실 내부에서 수직 높이에 따라 온도가 어떻게 달라지는지 알아보았다. 시험용 차량을 온도 제어가 가능한 대형 챔버에 넣고, 저온으로 유지하였다. 객차 내부에는 온도를 측정할 수 있는 열전대를 다양한 높이에 설치하고, 난방기를 가동한 후에 객실 내부에서 높이에 따른 온도를 측정하였다. 실험결과 객차 내부 바닥에서의 높이가 높아질수록 온도도 크게 상승함을 볼 수 있었으며, 이 온도 차이는 5도~8도까지 나타나 동일한 실내공간에서 앉아 있는 승객과 서 있는 승객이 다른 온도에 노출됨을 알 수 있었다. 본 결과는 향후 객실의 열적 쾌적성을 향상시키는 방안을 도출하는데 적용될 수 있을 것으로 기대된다.