PubMed를 통해 살펴 본 알레르기 비염에 대한 보완 의학적 최신 연구 경향

정혜미,조민정,서운교,Jung, Hye-Mi,Cho, Min-Jung,Seo, Un-Kyo 대한한방내과학회 2009 大韓韓方內科學會誌 Vol.30 No.3

Objectives : To study trends in complementary medical therapy for the allergic rhinitis. This study analyzed research on allergic rhinitis in PubMed. Methods : We searched PubMed related to complementary medical therapy for allergic rhinitis. We analyzed 25 research papers and examined published journals, years countries, and their methods, objectives, results, interventions, participants, periods and instruments of assessment. Results : The method of studies was mostly randomized, double-blind, placebo-controlled trial. There were research papers concerning treatment and prevention with herbal medicine, acupuncture, diet, etc. There were more positive results compared to negative results for treatment and prevention. Most studies were carried out during the winter/spring period. The median for number of participants was 90.54 persons. Diagnostic criteria for enrolment were nasal symptoms, allergic skin test, serum, nasal discharge allergen specific IgE eosinophil, etc. Assessment for outcomes were nasal symptoms, serum, nasal discharge allergen specific IgE eosinophil and Quality of Life Questionnaire. Conclusions : It is necessary to study effects of acupuncture and herb medicines for allergic rhinitis and more in-depth research about trends in complementary medical therapy for allergic rhinitis.

고분자전해질연료전지 효율 향상을 위한 최적 물 관리 기법 연구

정혜미(Hye-Mi Jung),이관수(Kwan-Soo Lee),엄석기(Sukkee Um) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

The ideal fuel cell operating strategy concerning water transfer is to keep the ionomer membrane fully saturated and avoid the unfavorable water condensing. In this work, the theoretical models are developed and utilized to set up an optimal water management strategy preventing liquid water formation in the reactant supplying channels. It is further applied to find out the required humidity level of reactant feed streams satisfied with full saturation levels at the channels outlets as a function of the physical operating conditions (i.e., pressure, temperature, and fuel/oxidant utilization) with a gradual temperature increase in the coolant. In this model, the analytical results showed that the favorable water transport scenario (half of produced water transported back to anode) requires less humidification at the .gas channel inlets compared to the worst scenario (10% of the produced water diffused back to anode). It was also shown that for 80℃ operation of fuel cells, the reactants should be super-saturated and the coolant temperature difference less than 5℃ between the inlet and outlet has a significant effect on the humidification of reactant gases.

고분자 전해질 연료전지 매니폴드의 열유동 특성에 관한 수치적 연구

정혜미(Jung, Hye-Mi),엄석기(Um, Sukkee),손영준(Sohn, Young-Jun),박정선(Park, Jungsun),이원용(Lee, Won-Yong),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2005 신재생에너지 Vol.1 No.2

The effects of internal manifold designs on the reactants feed-stream in Polymer Electrolyte Fuel Cells [PEFCs] is studied to figure out flow and thermal distribution patterns over an entire fuel cell stack. Reactants flows are modeled either laminar of turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-deter-mined for computational analysis. In this work, numerical models for reactants feed-stream In the PEFC manifolds are classified Into two major flow patterns: Z-shape and U-shape. Several types of manifold geometries are analyzed to find the optimal manifold configurations. The effect of heat generation in PEFC on the flow distribution is also Investigated applying a simplified heat transfer model in the stack level (i.e. multi-cell electrochemical power-generation unit). This modeling technique Is well suited for many large scale problems and this scheme can be used not only to account for the manifold flow pattern but also to obtain Information on the optimal design and operation of PEFC systems.

수송용 연료전지 스택의 탄소 계열 분리판 표면에 형성된 바나듐 산화물 다층 박막의 온도-저항 특성에 관한 연구

정혜미(Hye-Mi Jung),노정훈(Jung-Hun Noh),엄석기(Sukkee Um) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

The present experimental study was carried out to examine the applicability of crystalline vanadium oxide thin films as a potential electrical heat source. The thin solid films were formed uniformly along the edges of carbon-based separators to enhance cold-start performance of fuel cells for transportation applications. The multi-layered crystalline vanadium oxide films were synthesized by using 0.5M vanadium alkoxide precursor and then deposited onto porous graphite plates with a gas-impermeable resin through dip-coating technique and a subsequent post-heat treatment under vacuum conditions. The temperature-resistance properties, the quantitative analysis of the elemental composition, and the microstructure of the vanadium oxide films were investigated using 4-point probe, EDX, and FE-SEM, respectively. In this study, the temperature dependent electrical properties of the sol-gel derived vanadium-based films onto graphite plates were characterized by a Boltzmann sigmoidal regression in the temperature range of -20 ?? 80℃. Also, the theoretical discussion of the surface morphology with pore-induced shrinkage cracking in the films was presented.

연료전지 차량의 냉시동성 개선을 위한 금속 분리판 표면의 바나듐 산화물 박막 제조 및 특성 분석에 관한 연구

정혜미(Hye-Mi Jung),노정훈(Jung-Hun Noh),임세준(Se-Joon Im),이종현(Jong Hyun Lee),안병기(Byung Ki Ahn),엄석기(Sukkee Um) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.6

냉시동 성능 개선은 연료전지 차량의 고분자 전해질 연료전지 발전 모듈 및 시스템의 내구성과 신뢰성 향상의 측면에서 매우 중요하다. 이에 본 연구에서는 영하의 기후에서 연료전지 차량의 초기 구동 시 금속 분리판 표면에 형성된 바나듐 산화물 박막의 자기 발열 특성을 이용하여 신속한 온도 상승 구현이 가능한 냉시동 향상 기술을 제안하고, 실험적 방법을 통해 그 적용 가능성을 검증하였다. 졸-겔 침지 법에 의해 제조된 바나듐 산화물 박막의 특성 평가를 위해 X 선 회절, 광전자 분광, 전자 주사 현미경을 이용한 화합물 조성 및 미세구조 분석, 4-탐침법을 이용한 -20 ~ 80℃의 온도 구간에서의 온도-저항 이력 특성 분석을 각각 수행하였다. 본 실험 결과, 냉시동 조건에서 박막의 자기 발열량은 연료전지 내부의 생성 수 결빙 방지에 필요한 열 에너지를 모두 충족시킬 수 있음을 확인하였다. The enhancement of the cold-start capability of polymer electrolyte fuel cells is of great importance in terms of the durability and reliability of fuel-cell vehicles. In this study, vanadium oxide films deposited onto the flat surface of metallic bipolar plates were synthesized to investigate the feasibility of their use as an efficient self-heating source to expedite the temperature rise during startup at subzero temperatures. Samples were prepared through the dip-coating technique using the hydrolytic sol-gel route, and the chemical compositions and microstructures of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. In addition, the electrical resistance hysteresis loop of the films was measured over a temperature range from -20 to 80℃ using a four-terminal technique. Experimentally, it was found that the thermal energy (Joule heating) resulting from self-heating of the films was sufficient to provide the substantial amount of energy required for thawing at subzero temperatures.

차량용 연료전지 엔진의 금속 분리판 표면에 형성된 바나듐 기반 박막 저항체의 온도 의존성 전기적 특성 연구

정혜미(Hye-Mi Jung),노정훈(Jung-Hun Noh),엄석기(Sukkee Um) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

In the present study, vanadium oxide thin film resistors have been coated on the flat surface of metallic separators for cold start improvement of automotive fuel cell engines. The resistors have been fabricated to examine applicabilities as a source of thaw heat in subfreezing environments. We have prepared samples by a vanadium-based sol-gel route in combination with a dip-coating process and then temperature-induced electrical properties of these films have been directly measured over the temperature range -20 ~ 80℃ using 4-point probes installed in a thermo-hygrostat. It was found that the maximum value of electrical resistance of the film resistor with 0.385㎛ average thickness was about 1.65Ω at -20℃ and the corresponding temperature rise was approximately 45℃. The results show that the vanadium-based thin film resistors on metallic separators can be applied to enhance cold star capability of fuel cell vehicles by minimizing the electrical energy consumed in thaw.

차량용 연료전지 스택의 안정적 반응 가스 공급을 위한 중앙 유동 분배기 형상 설계에 관한 수치적 연구

정혜미(Jung, Hye-Mi),엄석기(Um, Suk-Kee),정희석(Jeong, Hui-Seok),이성호(Lee, Seong-Ho),서정도(Seo, Jeong-Do),손영진(Son, Yeong-Jin) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05

In this study, two types of central flow distributor designs are presented and compared to obtain the optimal compact design which has the least flow resistance and the uniform flow distribution in a vehicular fuel cell stack. For effective and reliable prediction on the thermo-flow characteristics of the reactants flow over the entire fuel cell stack domain, open channel flow in the bipolar plates of the power generating cells were simulated by applying a simplified flow resistance model with an empirical porous concept. A number of case studies were performed to figure out an optimal configuration of a central flow distributor device in terms of the time-dependent thermo-flow behavior and load-dependent flow distribution. The results showed that the stable and load-independent thermo-flow uniformity is very design specific, which is closely associated with the design of central manifolding devices in order to achieve the enhanced volumetric power density and the reliable long-lasting operating of fuel cells.

고분자 전해질 연료전지의 매니폴드 설계 및 해석

정혜미(JUNG, Hye-Mi),엄석기(UM, Sukkee),박정선(PARK, Jungsun),이원용(LEE, Won-Yong),김창수(KIM, Chang-Soo) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

The effects of internal manifold designs the reactant feed-stream in Polymer Electrolyte Fuel Cells (PEFCs) is studied to figure out mass flow-distribution patterns over an entire fuel cell stack domain. Reactants flows are modeled either laminar or turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-determined for computational analysis. In this work, numerical models for reactant feed-stream in the PEFC manifolds are classified into two major flow patterns: Z-shape and U-shape. Several types of manifold geometries are analyzed to find the optimal manifold configurations. The effect of heat generation in PEFC on the flow distribution is also investigated applying a simplified heat transfer model in the stack level (i.e. multi-cell electrochemical power-generation unit). This modeling technique is well suited for many large scale problems and this scheme can be used not only to account for the manifold flow pattern but also to obtain information on the optimal design and operation of a PEMC system.

최적 열/물관리를 위한 고분자 전해질 연료전지의 냉각 유로 설계 및 작동 조건에 관한 연구

정혜미(Hye-Mi Jung),박정선(Jungsun Park),김서영(Seo Young Kim),엄석기(Sukkee Um) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

In a typical operation of a PEFC stack, the cooling system must be able to keep the stack temperature within a proper range to achieve high efficiency and avoid any damage of the core components of fuel cells under various physical conditions including temperature and humidity. In this study, comprehensive threedimensional modeling for a single cell including coolant sections on the far-outer sides is first introduced for in-depth analysis of the heat and mass transport phenomena by temperature, fuel/oxidant utilization and humidity for the heat and water management. It is also applied to evaluate the representation of temperature variation (RTV) of PEFC stack due to the cooling passage pattern, material and operating temperature of direct stack cooing system. The outcome of the present study can be greatly applied to develop advanced heat and water management strategy and improve the long-term PEFC performance.

Synthesis and Evaluation of Variable Temperature-Electrical Resistance Materials Coated on Metallic Bipolar Plates

정혜미(Jung, Hye-Mi),노정훈(Noh, Jung-Hun),임세준(Im, Se-Joon),이종현(Lee, Jong Hyun),안병기(Ahn, Byung Ki),엄석기(Um, Sukkee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

For the successful cold starting of a fuel cell engine, either internal of external heat supply must be made to overcome the formation of ice from water below the freezing point of water. In the present study, switchable vanadium oxide compounds as variable temperature-electrical resistance materials onto the surface of flat metallic bipolar plates have been prepared by a dip-coating technique via an aqueous sol-gel method. Subsequently, the chemical composition and micro-structure of the polycrystalline solid thin films were analyzed by X-ray diffraction, X-ray fluorescence spectroscopy, and field emission scanning electron microscopy. In addition, it was carefully measured electrical resistance hysteresis loop over a temperature range from -20?C to 80?C using the four-point probe method. The experimental results revealed that the thin films was mainly composed of Karelianite V₂O₃ which acts as negative temperature coefficient materials. Also, it was found that thermal dissipation rate of the vanadium oxide thin films partially satisfy about 50% saving of the substantial amount of energy required for ice melting at -20?C. Moreover, electrical resistances of the vanadium-based materials converge on an extremely small value similar to that of pure flat metallic bipolar plates at higher temperature, i.e. T{geq}40?C. As a consequence, experimental studies proved that it is possible to apply the variable temperature-electrical resistance material based on vanadium oxides for the cold starting enhancement of a fuel cell vehicle and minimize parasitic power loss and eliminate any necessity for external equipment for heat supply in freezing conditions.