• 제목/요약/키워드: internal reaction rate

검색결과 196건 처리시간 0.027초

균형상살 검출 알고리즘에서 검출과 관련된 설계변수의 민감도 해석 몇 최적화 (Sensitivity Analysis and Optimization of Design Variables Related to an Algorithm for Loss of Balance Detection)

  • 고병규;김광훈;손권
    • 대한의용생체공학회:의공학회지
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    • 제32권1호
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    • pp.7-14
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    • 2011
  • This study suggested an optimized algorithm for detecting the loss of balance(LOB) in the seated position. And the sensitivity analysis was performed in order to identify the role of each design variable in the algorithm. The LOB algorithm consisted of data processing of measured signals, an internal model of the central nervous system and a control error anomaly(CEA) detector. This study optimized design variables of a CEA detector to obtain improved values of the success rate(SR) of detecting the LOB and the margin time(MT) provided for preventing the falling. Nine healthy adult volunteers were involved in the experiments. All the subjects were asked to balance their body in a predescribed seated posture with the rear legs of a four-legged wooden chair. The ground reaction force from the right leg was measured from the force plate while the accelerations of the chair and the head were measured from a couple of piezoelectric accelerometers. The measured data were processed to predict the LOB using a detection algorithm. Variables S2, h2 and hd are related to the detector: S2 represents a data selecting window, h2 a time shift and hd an operating period of the LOB detection algorithm. S2 was varied from 0.1 to 10 sec with an increment of 0.1 sec, and both h2 and hd were varied from 0.01 to 1.0 sec with an increment of 0.01 sec. It was found that the SR and MT were increased by up to 9.7% and 0.497 sec comparing with the previously published case when the values of S2, h2 and hd were set to 4.5, 0.3 and 0.2 sec, respectively. Also the results of sensitivity analysis showed that S2 and h2 had considerable influence on the SR while these variables were not so sensitive to the MT.

저탄장 자연발화 현상의 수치해석적 연구 (Numerical Study on the Phenomenon of Spontaneous Ignition of Coal Stockpile)

  • 김철진;박이선;손채훈
    • 대한기계학회논문집B
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    • 제34권7호
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    • pp.721-727
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    • 2010
  • 석탄을 야적해두는 저탄장에서 석탄의 자연발화 현상은 안전 문제와 더불어 심각한 경제적 손해를 야기한다. 저탄장에서의 자연발화는 석탄의 산화반응으로 방출되는 열량이 주위로 손실되는 열량보다 클 때 발생한다. 본 연구에서는 2차원 비정상 상태 수치해석을 통해 자연발화 현상을 모사하였고, 수치해석 결과의 타당성을 실험 결과와 비교하여 검증하였다. 수치해석을 통해 구한 시간에 따른 저탄 내부 온도의 변화 곡선은 실험을 통해 측정한 데이터와 잘 일치하였다. 자연발화 인자인 공극률에 따라 저탄장 내부온도 변화 및 압력, 산소 질량 분율의 변화 양상을 분석하였다. 계산 결과를 토대로, 저탄형태의 변화에 따라 저탄장 내부에서의 시간에 따른 온도 변화를 비교 검토하였다. 열점의 형성과 자연발화 메커니즘을 분석하여 제시하였다.

상엽 에탄올가용분획의 글루코스전달체, acetyl-CoA 카복시라제 및 렙틴 mRNA 발현에 미치는 영향 (Effects of Mori Folium Ethanol Soluble Fraction on mRNA Expression of glucose transporters, acetyl-CoA carboxylase and leptin)

  • 류정화;육창수;정성현
    • 약학회지
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    • 제42권6호
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    • pp.589-597
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    • 1998
  • Effects of Mori Folium Ethanol Soluble Fraction (MFESF) on mRNA expression of glucose transporters, acetyl-CoA carboxylase (ACC) and leptin were examined in db/db mice. 500 and 1000mg/kg dose for MFESF (designated by SY 500 and SY 1000, respectively) and 5mg/kg dose for acarbose were administered for 6 weeks. Quantitations of glucose transporters (GLUT-2 and GLUT-4), ACC and leptin mRNA were performed by RT-PCR and in vitro transcription with co-amplification of rat ${\beta}$-actin gene as an internal standard. Muscular GLUT-4 mRNA expression in MFESF-treated groups were increased dose dependently. On the other hand, MFESF caused the GLLT-4 and leptin mRNA expressions in adipose tissue to decrease dose dependently, which means that triglyceride synthesis in adipocytes might be decreased and consequently signals adipocytes to inhibit the synthesis and release of leptin. Hepatic ACC mRNA expression in MFESF-treated groups was also decreased. and this may result in lowering of serum triiglyceride level. In contrast, liver GLUT-2 mRNA expressions in MFESF-treated and acarbose groups were increased. Higher rate of glucose uptake into hepatocytes is known to inhibit a phosphoenolpyruvate carboxykinase (PEPCK)-catalyzed reaction, which is a rate-limiting step in gluconeogenesis.

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Effects of Sulfuric Acid Concentration and Alloying Elements on the Corrosion Resistance of Cu-bearing low Alloy Steels

  • Kim, Ki Tae;Kim, Young Sik
    • Corrosion Science and Technology
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    • 제17권4호
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    • pp.154-165
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    • 2018
  • During the process of sulfur dioxide removal, flue gas desulfurization equipment provides a serious internal corrosion environment in creating sulfuric acid dew point corrosion. Therefore, the utilities must use the excellent corrosion resistance of steel desulfurization facilities in the atmosphere. Until now, the trend in developing anti-sulfuric acid steels was essentially the addition of Cu, in order to improve the corrosion resistance. The experimental alloy used in this study is Fe-0.03C-1.0Mn-0.3Si-0.15Ni-0.31Cu alloys to which Ru, Zn and Ta were added. In order to investigate the effect of $H_2SO_4$ concentration and the alloying elements, chemical and electrochemical corrosion tests were performed. In a low concentration of $H_2SO_4$ solution, the major factor affecting the corrosion rate of low alloy steels was the exchange current density for $H^+/H_2$ reaction, while in a high concentration of $H_2SO_4$ solution, the major factors were the thin and dense passive film and resulting passivation behavior. The alloying elements reducing the exchange current density in low concentration of $H_2SO_4$, and the alloying elements decreasing the passive current density in high concentration of $H_2SO_4$, together play an important role in determining the corrosion rate of Cu-bearing low alloy steels in a wide range of $H_2SO_4$ solution.

고분자전해질형 연료전지의 가습 방법에 대한 연구 (A Study of Humidification Method in PEMFC)

  • 한덕수;김준범
    • 전기화학회지
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    • 제6권3호
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    • pp.212-216
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    • 2003
  • 고분자전해질형 연료전지에 사용되는 외부 및 내부 가습기를 통과한 반응 기체의 상대습도와 온도를 측정한 자료가 실시간으로 컴퓨터에 입력되어지는 시스템을 자체적으로 구성하였다. 이 시스템을 이용하여 측정한 경우 10-20분이 경과한 후에 습도 값이 안정되었으므로 가습 측정치에 대한 신뢰성을 향상시킬 수 있었으며, 여러 가지 가습의 영향을 해석할 수 있었다. 측정 장비의 이상을 초래할 수 있는 상대 습도가 $100\%$부근의 영역에서 지속적으로 측정을 수행할 경우 센서의 오작동 내지 고장의 원인이 될 수 있었으므로 실험시 주의가 필요하였다. 가습기를 통과한 반응기체는 유량이 증가할수록 가습되는 양은 증가하나, 일정 유량 이상이 되면 그 증가폭이 감소하는 경향을 보였는데 이는 가습기 출 통과하는 기체의 체류 시간 영향에 기인한 것으로 추정되어진다.

다공성 철 분말을 이용한 열전지용 열원 적합성 연구 (Study on the Suitability of Heat Source for Thermoelectric Cells Using Porous Iron Powder)

  • 김지연;윤현기;임채남;조장현
    • 한국전기전자재료학회논문지
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    • 제35권4호
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    • pp.377-385
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    • 2022
  • Thermal batteries are specialized as primary reserve batteries that operate when the internal heat source is ignited and the produced heat (450~550℃) melts the initially insulating salt into highly conductive eutectic electrolyte. The heat source is composed of Fe powder and KClO4 with different mass ratios and is inserted in-between the cells (stacks) to allow homogeneous heat transfer and ensure complete melting of the electrolyte. An ideal heat source has following criteria to satisfy: sufficient mechanical durability for stacking, appropriate heat calories, ease of combustion by an igniter, stable combustion rate, and modest peak temperature. To satisfy the aforementioned requirements, Fe powder must have high surface area and porosity to increase the reaction rate. Herein, the hydrothermal and spray drying synthesis techniques for Fe powder samples are employed to investigate the physicochemical properties of Fe powder samples and their applicability as a heat source constituent. The direct comparison with the state-of-the-art Fe powder is made to confirm the validity of synthesized products. Finally, the actual batteries were made with the synthesized iron powder samples to examine their performances during the battery operation.

급성기 의료기관의 일혈 발생 현황 및 임상간호사의 일혈 예방 및 관리에 대한 지식과 태도에 관한 연구 (Incidence of Extravasation in Acute Care Hospitals and Nurses' Knowledge and Attitude toward Extravasation Prevention and Management)

  • 김정윤;이윤진;고영옥;조현진;김희정;주명진;김미진
    • 임상간호연구
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    • 제28권1호
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    • pp.13-22
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    • 2022
  • Purpose: Extravasation of diagnostic and therapeutic materials might occur when the intravascular solution leaks into the surrounding tissues. Injury associated with extravasation depends on various factors. It may range from mild skin reaction to severe necrosis. However, the incidence rate for extravasation is largely unknown because of the limited reporting in Korea. Therefore, this study was conducted to identify the incidence of extravasation and nurses' attitude and knowledge of extravasation for providing high-quality nursing care. Methods: Three acute care hospitals were surveyed to estimate the occurrence of extravasation. Knowledge and attitude toward extravasation were investigated from 793 nurses working in six hospitals. Results: The incidence rate of extravasation was 0.5%. Extravasation commonly occurred in elderly patients aged 66 or older (59.9%) and internal medicine (48.2%), and it happened 13.73±20.68 days after hospitalization on average. It mostly occurred in the forearm site (52.9%) and was mainly caused by parenteral nutrition (33.6%). The mean scores of nurses' knowledge and attitude were 14.63±2.86 and 28.91±36.00, respectively. There was a significant negative correlation between the subjects' knowledge and attitude (r=-.11, p=.002). Conclusion: It is necessary to have a reporting system that can accurately monitor the occurrence of extravasation for patient safety management. In addition, it is necessary to develop a protocol that can be applied to clinical practice and a nurse education program.

The Investigation of Treatment of Pistachio Processing Industrial Wastewater by Electrochemical Methods in Terms of Chemical Oxygen Demand and Total Phenol Removal

  • Alper Erdem Yilmaz;Baybars Ali Fil;Murat Tolga Yilmaz;Serkan Bayar;Zuhal Koksal
    • Journal of Electrochemical Science and Technology
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    • 제15권1호
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    • pp.178-189
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    • 2024
  • This work aims to investigate the efficiency of electrocoagulation (EC) of pistachio processing industrial wastewater (PPIW) using the continuous EC process. The tubular reactor made of stainless steel with an internal diameter of 60 mm was used as a cathode electrode. The effect of some parameters was examined on the removal of chemical oxygen demand (COD) and total phenols (TP) removal efficiency. The influences of the initial pH of wastewater (from 4 to 8), flow rate (from 25 to 125 mL/min), current density (from 7 to 21 mA/cm2), and supporting electrolyte type (NaCl, NaNO3, and Na2SO4), supporting electrolyte concentration (from 10 to 100 mg/L NaCl) on removal efficiency were investigated to determine the best experimental conditions. The examination of the physico-chemical parameters during the EC treatment showed that the best removal efficiency was obtained under conditions where the flow rate was 25 mL/min (20 min reaction time), the pH value was 5.2, and the current density was 21 mA/cm2 has set. Under these experimental conditions, COD and TP removal efficiency were found to be 75% and 97%, respectively, while energy consumption was 18.5 kW h/m3. The study results show that the EC can be applied to PPIW pre-treatment.

수종의 흡수성 차단막의 생체 분해도와 조직학적 반응 (Resorbability and histological reaction of bioabsorbable membranes)

  • 석헌주;권석훈;김창성;최성호;전동원;김종관
    • Journal of Periodontal and Implant Science
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    • 제32권4호
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    • pp.781-800
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    • 2002
  • The major goals of periodontal therapy are the functional regeneration of periodontal supporting structures already destructed by periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. With the development of non-resorbable membrane, GTR has proved to be the representive technique of periodontal regeneration. However, due to various clinical problems of non-resorbable membrane, resorbable membrane was developed and it showed to be clinically effective. The newly developed Para-Dioxanone membrane has a characteristic of non-woven fabric structures which is different from the generally used membranes with structure of mesh form. In addition, Chitosan membrane has been developed to apply its adventage maximally in GTR. Although a number of different types of membranes had been clinically used, researches on absorption rate of membranes were inadequate and limited to subjective opinions. However, since long term period of resorption and space maintenance are required in implant or ridge augmentation, accurate verification of resorption rate is clinically important. In this study, we had implanted Resolut(R), Biomesh(R), Para-Dioxanone membrane and Chitosan membrane (Size : 4mm ${\times}$ 4mm) on dorsal side of Sprague Dawley rat, and sacrified them after 4 weeks, 8 weeks, 12 weeks respectively. Histologic observation was carried out, and the following results were obtained by calculating the objective resorption rate. 1. In case of Resolut(R), external resorption took place initially, followed by internal resorption. Surface area are 5.76${\pm}$2.37$mm^2$, 4.90${\pm}$l.06$mm^2$, 4.90${\pm}$0.98$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 31.6${\pm}$4.5%, 52.8${\pm}$9.4%, 56.4${\pm}$5.1% respectively. 2. Biomesh(R) showed a pattern of folding, relatively slow resorption rate with small size of membrane. Surface area are 3.62${\pm}$0.82$mm^2$, 3.63${\pm}$0.76$mm^2$, 4.07${\pm}$1.14$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 26.1${\pm}$5.8%, 30.9${\pm}$3.4%, 29.2${\pm}$3.6%, respectively. 3. Para-Dioxanone membrane was surrounded by fibrous conncetive tissue externally, and resorption took place internally and externally. Surface area are 5.96${\pm}$1.05$mm^2$, 4.77${\pm}$10.76$mm^2$, 3.86${\pm}$0.84$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 30.7${\pm}$5.1%, 53.3${\pm}$4.4%, 69.5${\pm}$3.1%, respectively. 4. Each fiber of Chitosan membrane was surrounded by connective tissue and showed external resorption pattern. It showed little invasion of inflammatory cells and excellent biocompatability. The resorption rate was relatively slow. Surface area are 6.01${\pm}$2.01$mm^2$, 5.49${\pm}$1.3$mm^2$, 5.06${\pm}$1.38$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 31.3${\pm}$3.6%, 38.4${\pm}$3.80%, 39.7${\pm}$5.6%, respectively. Consequently, Para-Dioxanone membrane and Chitosan membrane are found to be clinically effective for their excellent tissue reaction and biocompatibility. Futhermore, the advantage of bone regenerating ability as well as the relatively long resorption period of Chitosan membrane, it might be widely used in implant or ridge augmentation.

환경친화적인 합성기유 후보물질로서의 몇가지 폴리올에스터 오일의 가수분해속도 비교 (Comparison of the Hydrolysis Rate of Several Polyol Ester Oils as a Candidate for Environmentally Adapted Synthetic Base Oil)

  • 한두희;마사부미마스꼬
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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    • pp.162-177
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    • 2001
  • 분자구조가 서로 다른 7종의 폴리올에스터 오일에 대한 가수분해속도가 측정되었다. 사용된 폴리올에스터는 2가 및 4가의 다가알콜과 서로 다른 탄소수의 직쇄 흑은 분기지방산으로 합성된 다가에스터 화합물이며, 이들의 가수분해반응은 p-톨루엔설폰산을 촉매로 사용하는 온건한 산성조건하에서 수행되었다 폴리올에스터 오일의 가수분해과정에서 생성되 는 부분에스터와 다가알콜 및 지방산 등의 구조가 확인되었고 반응시간의 경과에 따른 가수분해 생성물들의 농도가 측정되었다. 각 반응단계의 속도상수는 속도식과 실험적으로 얻은 각 화합물들의 농도로부터 최소제곱법에 의해 구하였고, 얻어진 가수분해 속도상수가 서로 비교되었다. 폴리올에스터 오일의 가수분해 속도는 지방산의 분자구조에 가장 크게 영향을 받는다. 즉, 직쇄지방산에 의한 폴리올에스터 오일은 분기지방산에 의한 폴리올에스터 오일보다 가수분해속도가 매우 마르며, 분기지방산에 의한 폴리을에스터 오일 중에서는 가지사슬의 모양과 위치가 가수분해속도에 영향을 미치는 것으로 확인되었다. 본연구에서 사용된 7종의 폴리올에스터 오일에 대한 가수분해속도는 물분자가 폴리올에스터 오일의 카르보닐 탄소를 공격할 때 인접한 가지사슬에 의한 입체장애효과를 비교함으로써 효과적으로 설명할 수 있다.

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