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신혁수, 김동범, 박진근, 이인환, 조해용 충북대학교 산업과학기술연구소 2013 산업과학기술연구 논문집 Vol.27 No.2
A valve spring retainer is a small disc and located at intake and exhaust valve stem of engine. The retainer supports a valve spring and transmits spring force to a valve. Force is applied to the retainer repeatedly by a rocker arm. Durability of the retainer is an important factor of performance. Weight of retainer affect dynamic performance of engine. Therefore, optimal strength and weight of the retainer design are needed. In this study, stress distribution and fracture load of retainer were analyzed by using FEM to design optimal strength and weight. Static load test was simulated by using commercial FEM code DEFORM-3D. Shapes of the retainer to reduce weight were designed and analyzed to verify validity of it. Simulated results and experimental ones were compared
Park, Jae Hyeok,Lee, Chang-Ha,Joo, Ji Bong,Bae, Dal-Hee,Shun, Dowon,Moon, Jong-Ho,Park, Young Cheol,Shin, Jong-Seon,Choi, Young-Chan,Jung, Doo-hwan,Park, Jaehyeon Taylor Francis 2016 Drying technology Vol.34 No.9
<P>Upgrading low-rank coal (LRC) through various strategies is always an important issue. Here, we report the production of hybrid coals and an evaluation of their characteristics for use as a fuel in power plants. The hybrid coals (HCKs) were prepared by a combination of drying and biomass impregnation into an Indonesian LRC followed by a precarbonization process. We used a top-spray fluidized-bed reactor for drying, biomass impregnation, and precarbonization to produce hybrid coals that have improved fuel characteristics in terms of heating value, moisture readsorption, and combustion patterns. A systematic study reveals that experimental parameters, such as a bed temperature, bioliquid spraying procedure, and precarbonization temperature strongly influence the characteristics of the resulting hybrid coal, meaning that they have an important role in upgrading LRC. In particular, the hybrid coal prepared by a process of simultaneous drying and bioliquid spraying followed by precarbonization at 200-300 degrees C showed high contents of fixed carbon, an improved heating value, lower moisture adsorption, and single combustion patterns in which the characteristics were dramatically upgraded for practical use as a fuel in power plants. In addition, the simultaneous process using a fluidized-bed reactor has great potential because it can achieve process simplification, reduce manufacturing costs, and handle coal particles easily.</P>
Hybrid Fuel Preparation Combining Glycerol-Derived Hydrogel and Coal and Its Characterization
Park, Se-Joon,Lee, Dong-Wook,Lee, Young-Joo,Bae, Jong-Soo,Hong, Jai-Chang,Kim, Joeng-Geun,Park, Jaehyeon,Park, Jae Hyeok,Shin, Jong-Seon,Choi, Young-Chan American Chemical Society 2013 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.52 No.46
<P>A number of countries are mixing wood biomass with coal in existing coal-fired power plants according to the implementation of renewable portfolio standard (RPS) and cap-and-trade systems; problems arise due to mixing of the two fuels which have different combustion reactivities. In the previous work, research on glycerol impregnated hybrid fuel (Hybrid Coal by Korea Institute of Energy Research; HCK) was conducted for the diversification of bioliquid and issues to be resolved through further study in the application of glycerol to Hybrid Coal were noted. As a solution, a hydrogel having a small quantity of poly vinyl alcohol (PVA) added to glycerol was applied in the present work. PVA allowed the solidification of glycerol and contributed to the binding energy being stronger among glycerol derivatives and the surface of coal pore; thus, the fuel loss by readsorption of water can be inhibited by setting hydrogel into coal pores.</P>
Hee Joon Shin,Ju Hyeok Lee,Dong Kyu Seo,Hong Rae Kim,Ok Kon Moon,Si Eun Park,Joo Hyun Park,Nyeon Jun Kim,Kyung Ok Min 국제물리치료학회 2011 Journal of International Academy of Physical Ther Vol.2 No.1
In this case report, we investigated the effects of robot-assisted gait therapy in a chronic stroke patient using motor assessment and gait analysis. A patient who suffered from the right hemiparesis following the left corona radiata and basal ganglia infarction received 30 minutes of robot-assisted gait therapy, 3 times a week for 4 weeks. Outcome was measured using Motoricity index(MI), Fugl-Meyer assessment(FMA), modified motor assessment scale(MMAS), isometric torque, body tissue composition, 10-meter gait speed and gait analysis. After robot-assisted gait therapy, the patient showed improvement in motor functions measured by MI, FMA, MMAS, isometric torque, skeletal muscle mass, 10-meter gait speed. In gait analysis, cadence, single support time, double support time, step length, walking speed improvement in after robot-assisted gait therapy. The results of this study showed that robot-assisted gait therapy is considered to facilitate locomotor recovery of the chronic hemiparetic stroke patient.
LID 실증단지 모니터링시스템 구축 및 저류 효율성 분석
윤의혁(Yoon Eui hyeok),박정규(Park Jung kyu),신현석(Shin Hyun suk),이재혁(Lee Jae hyuk) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.5
모니터링시스템은 구축된 시설에 대한 효율적인 성능평가를 위하여 반드시 필요한 요소이다. 본 연구에서는 분산형 빗물관리 방식의 일원인 저영향개발(LID) 기법에 대하여 건축형, 도로형, 주차장형, 빗물정원형, 생태 공원형의 실증시설을 구축하였고, 각 실증시설에 대한 성능 평가를 위하여 모니터링시스템을 구축하였다. 모니터링시스템을 이용하여 LID 실증단지에서의 강우 규모에 따른 유입량-유출량에 대하여 소규모 LID 시설에서의 저류량 분석을 통하여 LID 실증시설의 일시적인 저류 효율성에 대하여 검토하였다. 그 결과 LID 실증단지 인근 시설 및 구조물에서 강우에 의하여 발생된 유량이 유입되어 건축형 및 도로형 실증시설에서는 유입량보다 유출량이 크게 관측되었으나, LID 실증시설 이외 외부의 영향을 받지 않은 주차장형 및 빗물정원형의 경우 54.69~100%의 우수한 일시적인 저류 효율을 나타냈다. 따라서 별도의 우수저류시설이 필요 없이 일시적인 저류 효과를 나타내는 LID 기법의 도입은 강우 발생에 따른 국부적 도시 홍수 및 침수를 조절하여 수해로부터 도시를 안전하게 보호하는 등 도시 침수 예방에 크게 기여할 것으로 판단된다. 그러나 본 연구에서는 단순한 유입량-유출량 분석을 통하여 LID 실증단지의 일시적인 저류 효율성만 계산하였기 때문에 향후 수문 모형을 통한 LID 시설의 검증이 요구된다. Monitoring systems are essential factors to evaluate facilities efficiently. In this study, we construct demonstrate complexes such as architectural type, road type, parking lot type, rain garden type, bioretention type which are the technic of Low Impact Development (LID), and set monitoring systems to conduct performance test of each facility. Moreover, we examine the temporal water storage efficiency of LID systems by analyzing relation between inlet-outlet flow discharge quantity under condition of rain intensity at small scale of LID facility by using monitoring system. Though architectural type and road type facilities reached high runoff discharge due to unexpected external inlet stormwater around LID demonstration facilities and structures, parking lot type and rain garden type facilities showed good water storage efficiency (54.69~100%) which are not affected by external factors except LID facilities. Therefore, application of LID technics nearby urban areas seem to mitigate flood disaster by reducing peak flow and delaying runoff velocity of stormwater with its temporal storage ability regardless of additional stormwater reservoirs. However this study only analyze storage efficiency of LID facility. Hence, additional verification of LID facility using hydrological model should be conducted for in the future study.
Effects of Ginseng Saponin on Modulation of Multidrug Resistance
Park, Jong-Dae,Kim, Dong-Sun,Kwon, Hyeok-Young,Son, Sang-Kwon,Lee, You-Hui,Baek, Nam-In,Kim, Shin-Il,Lee, Dong-Kwon The Pharmaceutical Society of Korea 1996 Archives of Pharmacal Research Vol.19 No.3
Multidrug resistance (MDR) has been a major problem in cancer chemotherapy. To overcome this problem, we prepared minor ginsenosides stereoselectively from ginseng saponins and searched for a ginseng component which is effective for inhibition of MDR. MDR inhibition activity was determined by measuring cytotoxicity to MDR cells using multidrug resistant human fibrocarcinoma KB V20C, which is resistant to 20 nM vincristine and expresses high level of mdr1 gene. Of several ginseng components, 20(S)-ginsenoside Rg_3$, a red ginseng saponin, was found to have the most potent inhibitory activity on MDR and it's concentration capable of inhibiting 50% growth was $82\muM$.
Park, Hyunmin,Lee, Keel Yong,Kim, Wanjung,Shin, Hee-Won,Wang, Dong Hwan,Ahn, Tae Kyu,Park, Jong Hyeok American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.5
<P>Organic photovoltaic devices are difficult to commercialize because of their vulnerability to chemical degradation related with oxygen and water and to physical degradation with aging at high temperatures. We investigated the photophysical degradation behaviors of a series of poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl C61-butyric acid methyl ester (PC<SUB>60</SUB>BM) bulk heterojunctions (BHJs) as a model system according to the donor–acceptor ratio. We found that the optimum P3HT:PC<SUB>60</SUB>BM ratio in terms of long-term stability differs from that in terms of initial cell efficiency. On the basis of cell performance decays and time-resolved photoluminescence measurements, we investigated the effects of oxygen and material self-aggregation on the stability of an organic photovoltaic device. We also observed the changes in morphological geometry and analyzed the surface elements to verify the mechanisms of degradation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-5/am302185f/production/images/medium/am-2012-02185f_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am302185f'>ACS Electronic Supporting Info</A></P>