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.

Dry Cleaning of Polluted Railroad Ballast using a Pilot-scale Ballast Cleaning Equipment

Youngmin Cho,Jae-Young Lee,Tae-Soon Kwon,Duck-Shin Park,Gi-Hwang Kim,Woo-Sung Jung 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Ruthenium bipyridyl complex-sensitized dechlorination of CCl₄ in aqueous micellar solutions under visible light

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.

Practical Application of Novel Physical Ballast Washing System to Soil Remediation In Polluted Rail Yard

Youngmin Cho,Jae-Young Lee,Tae-Soon Kwon,Duck-Shin Park,Woo-Sung Jung 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

High-Speed Low-Power Junctionless Field-Effect Transistor with Ultra-Thin Poly-Si Channel for Sub-10-nm Technology Node

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.

이산화탄소 흡탈착 장치를 이용한 실내공간 이산화탄소의 흡착 저감 연구

조영민(Youngmin Cho),양영민(Youngmin Yang),최진식(Jin-Sik Choi),권순박(Soon-Bark Kwon),박덕신(Duck-Shin Park),정우성(Woo-Sung Jung) 한국철도학회 2012 한국철도학회 학술발표대회논문집 Vol.2012 No.5

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.

Al2O3 흡착제를 이용한 객실용 이산화탄소 흡착연구

조영민(Youngmin Cho),최진식(Jin-Sik Choi),이지윤(Ji-Yun Lee),권순박(Soon-Bark Kwon),박덕신(Duck-Shin Park) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10

Carbon dioxide concentration of railroad passenger cabin is obliged to be kept lower than guideline values of 'Indoor air quality guideline for public transportations' but actual carbon dioxide concentration frequently exceeds this guideline value during the morning and evening rush hours. For improving comfortability and satisfaction of passengers concentration control method using Al2O3 adsorbents was presented. The adsorbent is made from Al2O3 and LiOH. Al2O3 perform as a frame and LiOH as a chemical adsorbent. The adsorbent performance experiment was carried out by measuring concentration change of Carbon dioxide in terms of flow initial concentration and amount of adsorbent. It is expexted that the obtained results will be used to lower carbon dioxide concentration of railroad passenger cabin.

외기 온도와 난방 출력의 철도차량 객실 온도에 대한 영향 연구

조영민(Cho, Youngmin),박덕신(Park, Duck-Shin),권순박(Kwon, Soon-Bark),정우성(Jung, Woo-Sung) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.9

최근 기후변화와 기상이변 등으로 동절기에 더욱 가혹한 기상 조건이 자주 보고되고 있다. 그러나, 철도차량의 난방 용량은 이렇게 극도로 추운 기후환경에서는 객실을 난방하기에 충분하지 않은 경우가 많으며, 이는 난방에 대한 승객의 민원 을 야기하는 주요 원인이 되고 있다. 본 연구에서는 외기 온도와 난방 출력이 객실 온도에 미치는 영향을 알아봄으로써 차량 의 난방용량에 따른 운행 가능한 외기온도를 실험적으로 도출하고자 하였다. 실험방법으로는 우선 시험용 철도차량을 대형 기후환경 챔버에 넣고, 다양한 외기온도조건을 모사하였다. 난방 장치 출력의 영향은 난방 장치의 출력을 변화시키면서 객실 의 온도를 측정하여 조사하였다. 외기온도가 -10 ℃인 조건에서는 난방기의 출력을 최대로 한 경우에도 객실의 평균 온도는 14.0 ℃에 불과하여, 동절기의 객실온도 최소 요구조건인 18 ℃보다 훨씬 낮았으나, 외기 온도가 0 ℃와 10 ℃인 경우의 객실 온도는 각각 26.1 ℃와 34.0 ℃였다. 내삽법으로 계산한 결과 객실 내부 온도를 18 ℃ 이상으로 유지할 수 있는 최저 외기온도 는 ?6.7 ℃임을 알 수 있었다. 객실 내부에서의 수직 온도 차이는 난방기 출력이 높을수록, 외기온도가 높을수록 커서 10 K 이상 차이가 나는 경우도 있었다. 그러나, 수평 온도 차이는 난방기 출력이나 외기온도에 무관하게 최대 2 K 이하로 매우 낮게 나타났다. 따라서, 우수한 난방성능을 확보하기 위해서는 수직 온도 차이를 줄이는 것이 중요함을 알 수 있었다. Recently, abnormally cold weather has been reported more frequently in winter due to the climate change and abnormal weather changes. On the other hand, the heating capacity of a railcar may be not enough to warm the cabin under severe cold climatic conditions, which is one of the reasons for the passengers’ complaints about heating. In this study, the effects of ambient temperature and heater power on the cabin temperature was investigated to obtain the minimum ambient temperature for the tested railcar. The test railcar was placed in a large-climatic chamber, and various ambient temperature conditions were simulated. The effects of the heater output were investigated by monitoring the cabin temperature under a range of heater output conditions. The mean cabin temperature was 14.0 ℃, which was far lower than the required minimum temperature of 18 ℃, under a ?10 ℃ ambient temperature condition with the maximum heat power. When the ambient temperature was set to 0 ℃ and 10 ℃, the maximum achievable cabin temperature was 26.1 ℃ and 34.0 ℃. Through calculations using the interpolation method, the minimum ambient temperature to maintain an 18 ℃ cabin temperature was ?6.7 ℃ for this car. The vertical temperature difference was higher with a higher power output and higher ambient temperature. The maximum vertical temperature difference was higher than 10 °C in some cases. However, the horizontal temperature difference vs. low temperature (< 2 °C) was independent of the power output and ambient temperature. As a result, it is very important to reduce the vertical temperature difference to achieve good heating performance.

[미발표] 카보네이트계 흡착제를 이용한 이산화탄소 흡착특성 연구

조영민(Youngmin Cho),홍승우(Seung-Woo Hong),양영민(Young-Min Yang),권순박(Soon-Bark Kwon),박덕신(Duck-Shin Park),정우성(Woo-Sung Jung),김희만(Hee-Man Kim) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.5

객실의 실내공기질은 ‘대중교통수단의 실내공기질 가이드라인’에 의하여 이산화탄소 농도를 일정 수준 이하로 유지하도록 하고 있다. 그러나, 지하철의 경우 환기가 어려우므로 이를 해결하기 위해 이산화탄소 흡착제를 적용하는 방안이 꾸준히 연구되고 있다. 그러나, 기존 흡착제의 경우 이산화탄소 흡착성능이 낮거나 재생이 불가능하다는 단점이 있다. 이에 본 연구에서는 이산화탄소의 흡착성능도 우수하고 재생도 용이한 카보네이트계 흡착제를 이용하여 이산화탄소를 흡착저감하는 방법을 연구하였다. 카보네이트의 함유량과 소성 온도 등에 따른 흡착성능을 알아보았다. 본 연구결과가 실용화될 경우, 혼잡시간대의 객실 내부 이산화탄소 농도를 낮은 수준으로 유지하여 실내공기질을 개선함과 동시에 환기횟수를 줄여 냉난방 에너지 비용도 절감할 수 있을 것으로 기대된다. Carbon dioxide concentration in subway cabin is advised to keep lower than certain limit values by “Guideline for Indoor Air Quality in Public Transportations”. However, the ventilation is not easy with subway cabin since the ventilation may cause the inflow of various pollutants residing in the subway tunnel. For this reason, the use of carbon dioxide adsorbent is studied. But, the development of efficient and regenerable carbon dioxide adsorbent is still required. In this paper, an efficient and regenerable carbon dioxide adsorbent, carbonate adsorbent was studied to reduce the indoor carbon dioxide concentration. Improvement of indoor air quality, and the saving of heating and cooling energy was expected by applying this carbon dioxide adsorbent.