Enhancement of the hydrogen productivity in microbial water gas shift reaction by <i>Thermococcus onnurineus</i> NA1 using a pressurized bioreactor

Kim, Min-Sik,Fitriana, Hana Nur,Kim, Tae Wan,Kang, Sung Gyun,Jeon, Sang Goo,Chung, Soo Hyun,Park, Gwon Woo,Na, Jeong-Geol Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.45

<P><B>Abstract</B></P> <P>Here, we developed a pressurized bioreactor system that increase carbon monoxide (CO) transfer efficiency in order to enhance the hydrogen productivity in the microbial water gas shift reaction by <I>Thermococcus onnurineus</I> NA1. The effects of CO pressure on the hydrogen production rate, CO consumption rate and the cell growth were investigated using small scale stainless steel bottles at various CO partial pressures. It was found that CO solubility increased by applying pressure can affect hydrogen production positively as long as the increased toxicity of CO is endurable to cells. The hydrogen productivity increased to some extent with CO pressure, but decreased drastically at the pressure higher than 4 bar. On the other hand, the effect of pressure itself on the cell's activity was not as significant as that of CO solubility increase. In the experiments at various system pressures with identical CO partial pressure of 1 bar, more than 80% of the cell activity remains even at total pressure of 10 bar. Also, it was important to determine the appropriate time to increase pressure for preventing excess CO in the reactor. Based on these results, a fermentation strategy for the pressurized system was designed and applied to a 5 L bioreactor with the continuous supply of the gas containing 60% CO. When the pressure was introduced to the bioreactor up to 4 bar at CO limitation condition, the unprecedented high productivity (360 mmol L<SUP>−1</SUP> h<SUP>−1</SUP>) could be obtained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO gas solubility increased by pressurizing can be beneficial to H<SUB>2</SUB> production. </LI> <LI> The impact of pressure per se was marginal. </LI> <LI> CO toxicity impacts were reduced by applying pressure at mass transfer limitation condition. </LI> <LI> When the pressure was introduced to the bioreactor, the unprecedented high productivity could be obtained. </LI> </UL> </P>

Photoreactive natural polymer for medical application

Hana Na,Yoshihiro Ito,Hyoungjae Lee,Shinhye Park,Siwoong Seo,Kwangil Kim,Taeil Son 한국당과학회 2011 한국당과학회 학술대회 Vol.2011 No.1

Mainly, chemical and physical methods have been used for immobilization of bioactive materials. However, there are some of drawbacks with those methods. For example, chemical method may produce potential toxic by-product and, in case of physical method, low efficiency of immobilized bioactive material is observed. To solve these problems, recently, the immobilization by photoreaction has been researched widely. The advantages of photo-immobilization are 1) high selectivity of chemical reactions or processes under mild conditions (ambient temperature of also much below), 2) typically no need for added catalysts or special solvents, 3) spatially addressable effects (2D and 3D structuring possible) and 4) applicable to very small and (relatively) large scales. To use for photo-immobilization, various natural polymers reacted by irradiation to ultra violet and visible light can be synthesized. It is considered that these photoreactive natural polymers can be applied for medical area to increase biocompatibility and functionality, for example, coating agent for bioinnert devices like stent and implant, anti-adhesive agent, wound dressing and bio-adhesive.

Stream Processing에서 I/O데이터 일관성을 고려한 성능 최적화

나하나(Hana Na),이준환(Joonwhan Yi) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.8

본 논문은 대량의 stream data를 처리하는 어플리케이션에서 하드웨어 가속기들이 접근하는 메모리가 non-cacheable에서 cacheable으로 변경됨에 따라 발생할 수 있는 데이터 일관성 문제를 고려하여 시스템 최적화를 진행하였다. 이를 위해 상위 수준 시뮬레이션을 통한 프로파일링 결과를 토대로 분석식을 만들어 활용하였다. 실험한 결과 여러 이미지 크기에서 메모리가 cacheable로 변경됨에 따라 평균 1.40배의 성능 향상을 보였다. 분석식의 주요 파라미터 최적화를 통해 최종적으로 3.88배의 성능 이득이 발생했으며, 항상 메모리가 cacheable인 경우의 성능이 항상 우월한 것은 아님을 확인할 수 있었다. Performance optimization of applications with massive stream data processing has been performed by considering I/O data coherency problem where a memory is shared between processors and hardware accelerators. A formula for performance analyses is derived based on profiling results of system-level simulations. Our experimental results show that overall performance was improved by 1.40 times on average for various image sizes. Also, further optimization has been performed based on the parameters appeared in the derived formula. The final performance gain was 3.88 times comparing to the original design and we can find that the performance of the design with cacheable shared memory is not always.

태풍 내습 시 발생 가능한 최대 풍속 산정을 통한 태풍의 사전 방재 시스템 기초 자료 구축

나하나 ( Hana Na ),박종길 ( Jong-kil Park ),정우식 ( Woo-sik Jung ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.3

For this study, WRF numerical modeling was performed, using RDAPS information for input data on typhoons affecting the Korean peninsula to produce wind data of 700hPa. RAM numerical modeling was also used to calculate 3-second gusts as the extreme wind speed. After comparing wind speeds at an altitude of 10 m to evaluate the feasibility of WRF numerical modeling, modeled values were found to be similar with measured ones, reflecting change tendencies well. Therefore, the WRF numerical modeling results were verified. As a result of comparing and analyzing these wind speeds, as calculated through RAM numerical modeling, to evaluate applicability for disaster preparedness, change tendencies were observed to be similar between modeled and measured values. In particular, modeled values were slightly higher than measured ones, indicating applicability for the prevention of possible damage due to gales. Our analysis of 3-second gusts during the study period showed a high distribution of 3-second gusts in the southeast region of the Korean peninsula from 2002-2006. The frequency of 3-second gusts increased in the central north region of Korea as time progressed. Our analysis on the characteristics of 3-second gusts during years characterized by El Nino or La Nina showed greater strength during hurricanes that affected the Korean peninsula in El Nino years.

광대역 디지털 수신기용 채널화기의 FPGA 구현을 위한 FFT 상위 레벨 시뮬레이터 구현 및 성능 분석

나하나(Hana Na),조태상(Taesang Cho),송장훈(Janghoon Song),주형준(Hyung-jun Ju),강종진(Jongjin Kang) 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.11

한반도 영향 태풍에 적합한 최대풍속반경 Part I: 선행 경험공식 평가

나하나(Hana Na),정우식(Woo-Sik Jung) 한국대기환경학회 2022 한국대기환경학회지 Vol.38 No.1

한반도 영향 태풍의 월별 최대풍 특징과 사례 연구 - 태풍 루사·매미·곤파스·볼라벤을 대상으로 -

나하나 ( Hana Na ),정우식 ( Woo-sik Jung ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.4

The present study analyzes the characteristics of 43 typhoons that affected the Korean Peninsula between 2002 and 2015. The analysis was based on 3-second gust measurements, which is the maximum wind speed relevant for typhoon disaster prevention, using a typhoon disaster prevention model. And the distribution and characteristics of the 3-second gusts of four typhoons, RUSA, MAEMI, KOMPASU, and BOLAVEN that caused great damage, were also analyzed. The analysis show that between May and October during which typhoons affected the Korean Peninsula, the month with the highest frequency was August(13 times), followed by July and September with 12 occurrences each. Furthermore, the 3-second gust was strongest at 21.2 m/s in September, followed by 19.6 m/s in August. These results show that the Korean Peninsula was most frequently affected by typhoons in August and September, and the 3-second gusts were also the strongest during these two months. Typhoons MAEMI and KOMPASU showed distribution of strong 3-second gusts in the right area of the typhoon path, whereas typhoons RUSA and BOLAVEN showed strong 3-second gusts over the entire Korean Peninsula. Moreover, 3-second gusts amount of the ratio of 0.7 % in case of RUSA, 0.8 % at MAEMI, 3.3 % at KOMPASU, and 21.8 % at BOLAVEN showed as "very strong", based on the typhoon intensity classification criteria of the Korea Meteorological Administration. Based on the results of this study, a database was built with the frequencies of the monthly typhoons and 3-second gust data for all typhoons that affected the Korean Peninsula, which could be used as the basic data for developing a typhoon disaster prevention system.

컨텍스트 인식 기반의 스마트홈 서비스 제안 - 어린 아이의 안전을 중심으로 -

나하나 ( Na Hana ) 한국디자인트렌드학회 2009 한국디자인포럼 Vol.24 No.-

오늘날의 집안환경은 디지털 정보처리의 기술과 전자통신의 발달로 인하여 인간이 안주하기 위한 필수적인 공간으로서의 역할을 할 뿐만 아니라 원격진료 및 교육, 홈쇼핑 등 인간의 보다 다양한 욕구를 수용할 수 있게 되었다. 이러한 네트워크 기반의 디지털 환경은 점점 더 지능화되어, 편리하고 안전하며 개인에게 맞는 효율적인 생활환경인 스마트홈을 구축하게 될 것이다. 집안환경을 개인화된 안락한 공간으로 디자인하기 위해서는 단지 더 많은 욕구를 수용하기 위한 기능을 추가하는 것이 아니라, 세분화된 사용자층을 연구하고 실현가능한 기술을 바탕으로 그들의 상황을 인식하여 그에 맞는 서비스를 제공할 수 있도록 해야 할 것이다. 본 연구는 특정 사용자층을 위한 새로운 스마트홈 서비스를 제안하기 위해 우선 유비쿼터스 컴퓨팅과 컨텍스트(Context) 인식에 대한 고찰을 토대로 스마트홈에 대한 배경지식을 쌓는다. 그리고 모든 사용자층의 관심사인 건강관리와 관련하여 구체적인 스마트홈 개발사례를 컨텍스트 인식의 과정에서 분석하였다. 대부분의 건강관리 스마트홈 사례들은 사용자의 집안활동을 장기적으로 모니터하고 이상징후가 있을 때 알려주는 형식이었지만, 컨텍스트를 인식하는 방법에 있어서는 센서의 종류와 정확성, 생활침범의 정도 등에 따라 여러 가지 방법이 있었다. 이러한 문헌연구와 사례연구를 바탕으로 어린 아이들을 사고로부터 보호하기 위한 스마트홈 서비스를 위해 컨텍스트 인식과정의 측면에서 구현 가능한 방법들이 제안되었다. 그 방법들은 모두 장단점이 있는데 장점은 강화되고 단점은 축소되어 가까운 미래에 실용화 되고, 다른 목적의 스마트홈 서비스 구현에도 이용되길 기대한다. Due to the development of digital data processing and electronic communication, the present home environment has become able to serve people`s various needs such as remote medical treatment or education and home shopping. The digital environment based on networks will become more intelligent and build a Smart Home which is convenient, safe and personalised. In order to design a home as a personalised, comfortable space, specified user groups need to be studied and provided with suitable services to their context using feasible technologies rather than simply add more functions to fulfil people`s needs. The research in this thesis is intended to propose a new Smart Home service for a specific user group. First, the theories of Ubiquitous Computing and Context-Awareness were studied as they are fundamental knowledge of Smart Home, and Smart Home was defined with its representing services. Then existing Smart Home systems for health care were analysed based on the general process of Context-Awareness. They all monitored the subject`s activities in the home environment to detect unusual trends that may indicate developmental or incipient health issues, but their methods were different. Last, based on the literature review, several approaches were proposed for a Smart Home service to prevent young children`s accidental injuries using possible technologies. The approaches are expected to be materialised in the near future by enhancing the strengths and weakening the weaknesses and also to be applied to another Smart Home services.

효율적인 DMAC 데이터 전송을 위한 성능 최적화

나하나(Hana Na) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.11

한반도 태풍내습 시 태풍경로별 나타나는 최대풍속 분포특성 연구

나하나(Hana Na),정우식(Woo-Sik Jung),박종길(Jong-Kil Park) 한국대기환경학회 2019 한국대기환경학회지 Vol.35 No.1