북한산 둘레길과 복합신소재 구조물이 갖는 특성

박기연 한국복합신소재구조학회 2011 복합신소재학회논문집 Vol.2 No.3

EO 및 SAR 위성의 개념설계도구 GUI 개발

박기연,염승용,김홍래,장영근 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11

위성의 개발 초기단계에서 사용자의 요구사항을 맞추고 개발방향을 정립하기 위해 임무를 설계하고 분석하는 과정과 위성시스템의 개념설계를 수행하는 과정을 반복하게 된다. 이러한 반복적인 과정에서 많은 시간과 비용을 소요하게 된다. GUI(Graphical User Interface) 기반의 소프트웨어인 SCDT (Spacecraft Conceptual Design Tool)를 사용함으로써 개발 초기단계에서 소요되는 시간과 비용을 현저하게 줄일 수 있다. GUI 기반의 소프트웨어는 입력된 값들의 수정이 용이하고 다양한 방법으로 사용자에게 결과를 보여줄 수 있다. 본 논문에서는 MATLAB GUI 기반의 SCDT를 개발한 과정 및 개발된 SCDT GUI를 소개한다. The development of high performance satellite requires considerable time and cost in early phase, in particular, during the development of mission and system requirements through iterations of conceptual design and mission design. The Spacecraft Conceptual Design Tool(SCDT), based on Graphical User Interface(GUI), was developed to reduce the time and cost for early phase development. Furthermore, GUI-based software can make the input values to be editable easily and show users design results in various way. In this paper, the development results of MATLAB GUI-based SCDT are introduced.

캡플레이트를 이용한 장스팬용 춤이 깊은 데크의 휨성능 개선

박기연,남윤선,최영환,김영호,최성모,Park, K.Y.,Nam, Y.S.,Choi, Y.H.,Kim, Y.H.,Choi, S.M. 한국강구조학회 2013 韓國鋼構造學會 論文集 Vol.25 No.5

철골구조의 층고를 절감을 위해 유럽을 중심으로 춤이 깊은 데크를 사용한 슬림플로어 공법이 개발되어 적용되고 있다. 국내에서도 장스팬과 층고절감을 요구하는 건물이 증가하고 있지만 7m이상 장스팬에 춤이 깊은 데크를 적용 시 과도한 처짐에 의한 사용성 문제를 초래한다. 따라서 본 연구는 장스팬에 적용되는 춤이 깊은 데크의 콘크리트 타설시 처짐의 사용성 및 개방형 단면의 불안정성에 의한 휨비틀림 등의 문제를 개선하는 방안으로 Cap형태의 plate(이하 '캡 플레이트')를 두가지 형태(Flat, Hat)로 개발하고 보강 길이와 위치의 최적화를 이론적 계산을 통해 도출하였다. 이 캡플레이트를 춤이 깊은 데크의 골상부에 일정 간격으로 설치하여 상부 개방형 불안전성을 극복하고 단면의 강성을 증대시켜 중앙부 처짐을 제어하고자 한다. 캡 플레이트의 설치위치와 보강길이에 따른 휨서능 개선의 효과를 해석과 실험을 통해 검증하고자 한다. Slim floor system using deep decks has been developed and employed in Europe to reduce the floor height of steel structures. Although long span buildings involving the issue of reducing floor height are being increasingly built in Korea, employing deep decks in more than 7m long span structures is likely to cause problems associated with excessive deflection. This study is applied to the long-span concrete casting of the deep deck plate usability of deflection due to bending and torsional instability of open cross-section, as a way to improve the problem of cap plates are suggested, and the optimum length of reinforcement and location are derived from theoretic estimation. The cap plates are placed on the deep decks with regular intervals to overcome the instability of open sections, improve the stiffness of the sections and control the deflection at the centers. The improvement in flexural capacity associated with the location of the cap plates and the length of reinforcement are verified through analysis and test.

대수 오차방정식 외란관측기를 이용한 직렬탄성 액추에이터의 강인제어

박기연,박승규,윤태성,곽군평 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.1

Muscle-strengthening robots have been developed in various ways and are used in military applications and recently in medical applications. The ball-screw-type series elastic actuator (SEA) as an actuator used in a muscle-strengthening robot is considerably advantageous in terms of cost because force sensors and harmonic gears can be replaced by variable resistors and ball screws. In this paper, we propose a new disturbance observer (DOB) for robust performance against a disturbance in the control of the ball-screw-type SEA with a ball screw, and show its performance by applying it to an SEA developed using a 3D printer. The proposed DOB had no difficulty in the design of a low-frequency filter as compared to the existing frequency domain DOB, and had the merit that the observer order was less than the state-space-design DOB and was easy to implement.

Assessment of Potential Biomarkers, Metallothionein and Vitellogenin mRNA Expressions in Various Chemically Exposed Benthic Chironomus riparius Larvae

박기연,곽인실 한국해양과학기술원 2012 Ocean science journal Vol.47 No.4

The objective of this study was conducted to identify the possibility of using Chironomus metallothionein (MT) and vitellogenin (VTG) as biomarkers of stress caused by endocrinedisrupting chemicals (EDCs), heavy metals, herbicides and veterinary antibiotics. We characterized the MT and VTG cDNA in Chironomus riparius and evaluated their mRNA expression profiles following exposure to different environmental pollutants. The gene expression analysis showed that the MT mRNA levels increased significantly after long-term exposure to cadmium (Cd), copper (Cu), Lead (Pb), di(2-ethylhexyl) phthalate (DEHP), and 2,4-dichlorophenoxyacetic acid (2,4-D). Moreover, the VTG mRNA expression increased significantly in C. riparius larvae exposed to BPA, NP, DEHP, Cd, 2,4-D and fenbendazole. Evaluation of the long-term effects of environmental pollutants revealed up regulation of Chironomus MT mRNA in response to DEHP exposure among EDCs, and the level of the VTG mRNA was increased significantly following treatment with Cd and herbicide 2,4-D at all concentrations in a dose-dependent manner. These results indicate that VTG could be used as a potential biomarker of herbicide and Cd as well as EDCs, while MT was a potential biomarker of heavy metals such as Cd, Cu, and Pb in aquatic environments.

Expression of Stress Response HSP70 Gene in Asian Paddle Crabs, Charybdis japonica, Exposure to Endocrine Disrupting Chemicals, Bisphenol A (BPA) and 4-Nonylphenol (NP)

박기연,곽인실 한국해양과학기술원 2013 Ocean science journal Vol.48 No.2

The Asian paddle crab, Charybdis japonica, is a potential bio-indicator reflecting marine sediment toxicity as well as a commercially important species living along coastal areas in Korea. This study investigated its stress response by looking at the heat shock protein (HSP70) gene of C. japonica when the organism is exposed to bisphenol A (BPA) and 4-nonylphenol (NP). We characterized partial sequence of HSP70 as the stressresponse gene of C. japonica. The nucleotide sequence of C. japonica HSP70 is over 90% homologous with the corresponding gene of other crabs. Phylogenetic tree analysis revealed a close relationship between C. japonica HSP70 and HSP70 in other species of lobster and shrimps. HSP70 mRNA transcripts were detected in all the examined tissues of C. japonica, with the highest level in gills, the organ that most frequently came into contact with the external BPA or NP-laden water. As no reference data were available for C. japonica crab exposure, the BPA and NP 24-h LC50 values have not been previously determined. The expression of the C. japonica HSP70 gene to various BPA or NP concentrations during short and longer times was assessed. Gene expression was significantly induced in concentration- and time-dependent manners after BPA or NP exposures. These results support the postulation that crab C. japonica HSP70 could be a potential stress response molecular marker to monitor marine ecosystems.

Characterization and Expression of Chironomus riparius Alcohol Dehydrogenase Gene under Heavy Metal Stress

박기연,곽인실 환경독성보건학회 2009 환경독성보건학회지 Vol.24 No.2

Metal pollution of aquatic ecosystems is a problem of economic and health importance. Information regarding molecular responses to metal exposure is sorely needed in order to identify potential biomarkers. To determine the effects of heavy metals on chironomids, the full-length cDNA of alcohol dehydrogenase (ADH3) from Chironomus riparius was determined through molecular cloning and rapid amplification of cDNA ends(RACE). The expression of ADH3 was analyzed under various cadmium and copper concentrations. A comparative and phylogenetic study among different orders of insects and vertebrates was carried out through analysis of sequence databases. The complete cDNA sequence of the ADH3 gene was 1134 bp in length. The sequence of C. riparius ADH3 shows a low degree of amino acid identity (around 70%) with homologous sequences in other insects. After exposure of C. riparius to various concentrations of copper, ADH3 gene expression significantly decreased within 1 hour. The ADH3 gene expression was also suppressed in C. riparius after cadmium exposure for 24 hour. However, the effect of cadmium on ADH3 gene expression was transient in C. riparius. The results show that the suppression of ADH3 gene by copper exposure could be used as a possible biomarker in aquatic environmental monitoring and imply differential toxicity to copper and cadmium in C. riparius larvae.

Vitellogenin Gene Characterization and Expression of Asian Paddle Crabs (Charybdis japonica) following Endocrine Disrupting Chemicals

박기연,곽태수,곽인실 한국해양과학기술원 2014 Ocean science journal Vol.49 No.2

Vitellogenin (VTG), the yolk-precursor lipoprotein, has been widely recognized as a biomarker for the detection of estrogenic activity in water-borne chemical pollutants. The Asian paddle crab, Charybdis japonica, is a potential bio-indicator for monitoring marine environments. The aim of this study was to identify the possibility of using C. japonica VTG as biomarkers of stress caused by endocrine disrupting chemicals (EDCs). We characterized a partial sequence of the VTG cDNA in the C. japonica crab and evaluated the crab’s mRNA expression profiles following exposure to different concentrations of bisphenol A (BPA) and 4-nonylphenol (NP) for 24 or 96 h. The sequencehomology of C. japonica VTG is over 93% in nucleotide and over 98% in amino acid with the corresponding gene of other crabs. Phylogenetic analysis revealed that the C. japonica VTG is an ortholog of other species of lobster and shrimp. Tissue distribution analysis of the C. japonica VTG mRNA revealed that the expression of VTG mRNA was highest in the ovary of females and hepatopancreas. The expression of the C. japonica VTG gene in various BPA or NP concentrations during shorter and longer times was assessed. The expression of VTG transcripts was significantly increased in the C. japonica crab exposed to BPA and NP at different concentrations for 24 h. The mRNA expression of the VTG gene was significantly induced in concentration- and time-dependent manners after BPA or NP exposures for 96 h. These results indicate that crab C. japonica VTG could be used as a potential biomarker of EDCs in marine environment monitoring.

Antioxidative-related Genes Expression Following Perfluorooctane Sulfonate (PFOS) Exposure in the Intertidal Mud Crab, Macrophthalmus japonicus

박기연,NIKAPITIYACHAMILANI LALANTHI,곽태수,곽인실 한국해양과학기술원 2015 Ocean science journal Vol.50 No.3

Perfluorooctane sulfonate (PFOS) is a persistent environmental contaminant that is used as a surfactant in various industries and consumer products. The intertidal mud crab, Macrophthalmus japonicus, is one of the most abundant macrobenthic creatures. In this study, we have investigated the effect of PFOS on the molecular transcription of antioxidant and detoxification signaling in M. japonicus crab. The selected stress response genes were superoxide dismutases (CuZnSOD and MnSOD), catalase (CAT), glutathione peroxidase (GPx), phospholipid hydroperoxide glutathione peroxidase (PHGPx), peroxiredoxin (Prx), and thioredoxin reductase (TrxR). Significant up-regulation of SODs and CAT was observed after 24 and 96 h exposure to PFOS at different concentrations. The gene expression levels of GPx, PHGPx, and TrXR were significantly up-regulated after exposure to PFOS for 96 h. The transcript levels of CAT and PHGPx were induced in dose- and time-dependent manners after PFOS treatments. However, Prx gene expression was significantly up-regulated in M. japonicus crabs exposed to 10 and 30 μg L-1 PFOS for 96 h. Additionally, PFOS toxicity in M. japonicus induced reduced survival rates at relatively high concentrations of PFOS exposure. Our findings support the contention that exposures to PFOS induced the response of genes related to oxidative stress and detoxification in M. japonicus crabs.

류마티스 관절염 활막세포에서 멜리틴이 PI3K경로의 활성화에 미치는 영향

박기연,백혜숙,이만영,한상미,최정윤 한국양봉학회 2014 한국양봉학회 학술대회 자료집 Vol.2014 No.4