• Title/Summary/Keyword: low temperature reduction

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Development of Lotus Root Bugak with Plasma Lipid Reduction Capacity by Addition of Opuntia ficus-indica var. saboten or Green Tea as a Coloring Agent (백년초 및 녹차 가루 첨가 연근 부각의 지질저하 기능성)

  • Kim, Mijeong;Hong, Sun Hee;Chung, Lana;Choe, Eunok;Song, Yeong-Ok
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.3
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    • pp.333-340
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    • 2014
  • The purpose of this study was to develop functional lotus root bugak with plasma lipid reduction capacity by controlling the color of batter used for bugak preparation. Lotus root, nearly colorless, was selected to observe color effects. Gardeniae fructus (GF), Opuntia ficus-indica var. saboten (OF), and green tea (GT), which are colored yellow, red, and green, respectively, were used as coloring agents. Fermented glutinous rice was prepared naturally during winter season by placing glutinous rice and water (1:2, w/w) together in a crock pot for 7 days. Coloring materials (10%, w/w) were blended with glue made from fermented glutinous rice flour to prepare the batter. Cooked lotus root was then mixed with a 1.1-fold amount of batter (w/w) and dried at room temperature. Lotus root bugak (LRB) is pan-fried with un-roasted sesame oil, which is traditionally used as frying oil in Korea. Low-density lipoprotein receptor knockout ($LDLr^{-/-}$) mice (n=36) were fed an atherogenic diet (AD) containing various types of LRB (10 g%) for 10 weeks. Plasma triglyceride, total cholesterol, and LDL-C concentrations decreased significantly in mice fed LRB prepared with OF batter (OFB) and GT batter (GTB) (P<0.05). Protein expression levels of fatty acid synthase (FAS) and 3-hydroxyl-3-methylglutaryl coenzyme A reductase (HMGCR) in the OFB and GTB groups were suppressed compared with the LRB group (P<0.05). In accordance with the results on FAS and HMGCR expression, sterol regulatory element binding protein-I and II (SREBP-I and II), which are responsible for the regulation of FAS and HMGCR gene expression, respectively, were down-regulated compared to the LRB group (P<0.05). In conclusion, the plasma lipid reduction activities of OFB and GTB could be mediated through down-regulation of FAS and HMGCR mRNA expression via suppression of regulatory molecules, SREBP-I and II, in $LDLr^{-/-}$ mice.

Derivation of Constraint Factors Affecting Passenger's In-Vehicle Activity of Urban Air Mobility's Personal Air Vehicle and Design Criteria According to the Level of Human Impact (도심항공모빌리티 비행체 PAV 탑승자 실내행위에 영향을 미치는 제약 요소 도출 및 인체 영향 수준에 따른 설계 기준)

  • Jin, Seok-Jun;Oh, Young-Hoon;Ju, Da Young
    • Science of Emotion and Sensibility
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    • v.25 no.1
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    • pp.3-20
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    • 2022
  • Recently, prior to the commercialization of urban air mobility (UAM), the importance of R&D for air transportation-related industries in urban areas has significantly increased. To create a UAM environment, research is being conducted on personal air vehicles (PAVs). They are key means of air transportation, but research on the physical factors influencing their passengers is relatively insufficient. In particular, because the PAV is expected to be used as a living space for the passengers, research on the effects of the physical elements generated in the PAV on the human body is essential to design an interior space that supports the in-vehicle activities of the passengers. Therefore, the purpose of this study is to derive the constraint factors that affect the human body due to the air navigation characteristics of the PAV and to understand the impact of these constraint factors on the bodies of the passengers performing in-vehicle activities. The results of this study indicate that when the PAV was operated at less than 4,000 ft, which is the operating standard, the constraint factors were noise, vibration, and motion sickness caused by low-frequency motion. These constraint factors affect in-vehicle activity; thus, the in-vehicle activities that can be performed in a PAV were derived using autonomous cars, airplanes, and PAV concept cases. Furthermore, considering the impact of the constraint factors and their levels on the human body, recommended constraint factor criteria to support in-vehicle activities were established. To reduce the level of impact of the constraint factors on the human body and to support in-vehicle activity, the seat's shape and built-in functions of the seat (vibration reduction function, temperature control, LED lighting, etc.) and external noise reduction using a directional speaker for each individual seat were recommended. Moreover, it was suggested that interior materials for noise and vibration reduction should be used in the design of the interior space. The contributions of this study are the determination of the constraint factors affecting the in-vehicle PAV activity and the confirmation of the level of impact of the factors on the human body; in the future, these findings can be used as basic data for suitable PAV interior design.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Dynamics of Phosphorus-Turbid Water Outflow and Limno-Hydrological Effects on Hypolimnetic Effluents Discharging by Hydropower Electric Generation in a Large Dam Reservoir (Daecheong), Korea (대청호 발전방류수의 인·탁수 배출 역동성과 육수·수문학적 영향)

  • Shin, Jae-Ki;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
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    • v.50 no.1
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    • pp.1-15
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    • 2017
  • Daecheong Reservoir was made by the construction of a large dam (>15 m in height) on the middle to downstream of the Geum River and the discharge systems have the watergate-spillway (WS), a hydropower penstock (HPP), and two intake towers. The purpose of this study was to investigate the limnological anomalies of turbid water reduction, green algae phenomenon, and oligotrophic state in the lower part of reservoir dam site, and compared with hydro-meteorological factors. Field surveys were conducted in two stations of near dam and the outlet of HPP with one week intervals from January to December 2000. Rainfall was closely related to the fluctuations of inflow, outflow and water level. The rainfall pattern was depended on the storm of monsoon and typhoon, and the increase of discharge and turbidity responded more strongly to the intensity than the frequency. Water temperature and DO fluctuations within the reservoir water layer were influenced by meteorological and hydrological events, and these were mainly caused by water level fluctuation based on temperature stratification, density current and discharge types. The discharges of WS and HPP induced to the flow of water bodies and the outflows of turbid water and nutrients such as nitrogen and phosphorus, respectively. Especially, when hypoxic or low-oxygen condition was present in the bottom water, the discharge through HPP has contributed significantly to the outflow of phosphorus released from the sediment into the downstream of dam. In addition, HPP effluent which be continuously operated throughout the year, was the main factor that could change to a low trophic level in the downreservoir (lacustrine zone). And water-bloom (green-tide) occurring in the lower part of reservoir was the result that the water body of upreservoir being transported and diffused toward the downreseroir, when discharging through the WS. Finally, the hydropower effluent was included the importance and dynamics that could have a temporal and spatial impacts on the physical, chemical and biological factors of the reservoir ecosystem.

Ecological variation between two populations of Thecodiplosis japonensis uchida et Inouye in Korea (솔잎혹파리 두 집단간(集團間)의 생태변이(生態變異))

  • Hwang, Yu Chul;Yim, Kyong Bin
    • Journal of Korean Society of Forest Science
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    • v.79 no.2
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    • pp.115-126
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    • 1990
  • This study was performed to find differences in phototaxis response of the larva, adult emergence, sex ratio and gall formation rate of Thecodiplosis japonensis Uchida et Inouye between two areas, north and south. Larvae from these two areas, Hweng-sung in north and Moo-an in south, both considered to be the sities of severe outbreak of the insect recently, were collected from the floor and transported to the entomology larboratory, Won-Kwang University in Iri, then overwintered. These larvae were used for various experimental purposes on various dates. The following results were obtained. 1. The sizes of larvae reached 2.45 in length, 0.70 in width for north, and 2.50 in length, 0.72 in width for sourth. It seems that the differents were not significant. 2. It is known that Leaving gall of larvae to the ground for the hibernation usually occurs on rainy days. For the larvae dispersion, the phototaxis response of the larvae was hypothesized. To check this, the author manipulated some different illumination intensities adjusting the distance between the glass tube in which 100 larvae were contained and electric bulb. The glass tubes were blackened all but except a small portion. The phototaxis responses between two areas seemed to be different particularly at low light intensities, 45, 145 and 1000 lux, The larvae from north assembled to the clear portion of the glass tube were more than 30 out of 100, however less than 30 in south sample regardless of the time passage. In either cases, the saturation points came after about 8 to 10 hours. If temperature units were used, the phototaxis curve= after 1 hour illumination between two areas provided significant differences. 3. The adult emergence of south area was lagged 10 days later than that of north area. The accumulated effective day-degrees of temperature for adult emergence were $934^{\circ}C$ for north area and $1180^{\circ}C$ for south area. The emerging duration of north area appeared to be in late May through the early of July and the peak emergence occurred in middle June that was approximately 15days earlier than that of south area. The sex ratio of female to male, regardless of area, was approximately 3 : 1. 4. The rates of gall formation of the red pine(Pinus densiflora Siebold et Zuccarini), 6-year-old seedlings, were as low as 9.94% for north area and 8.87% for south area. Through the close observation, the author presumed that the population reduction was greatly affected during the prepupa stage by relative moisture content and predators, such as spiders and ants presented on the ground.

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Magnetic Tunnel Junctions with AlN and AlO Barriers

  • Yoon, Tae-Sick;Yoshimura, Satoru;Tsunoda, Masakiyo;Takahashi, Migaku;Park, Bum-Chan;Lee, Young-Woo;Li, Ying;Kim, Chong-Oh
    • Journal of Magnetics
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    • v.9 no.1
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    • pp.17-22
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    • 2004
  • We studied the magnetotransport properties of tunnel junctions with AlO and AlN barriers fabricated using microwave-excited plasma. The plasma nitridation process provided wider controllability than the plasma oxidization for the formation of MTJs with ultra-thin insulating layer, because of the slow nitriding rate of metal Al layers, comparing with the oxidizing rate of them. High tunnel magnetoresistance (TMR) ratios of 49 and 44% with respective resistance-area product $(R{\times}A) of 3 {\times} 10^4 and 6 {\times} 10^3 {\Omega}{\mu}m^2$ were obtained in the Co-Fe/Al-N/Co-Fe MTJs. We conclude that AlN is a hopeful barrier material to realize MTJs with high TMR ratio and low $R{\times}A$ for high performance MRAM cells. In addition, in order to clarify the annealing temperature dependence of TMR, the local transport properties were measured for Ta $50{\AA} /Cu 200 {\AA}/Ta 50 {\AA}/Ni_{76}Fe_{24} 20 {\AA}/Cu 50 {\AA}/Mn_{75}Ir_{25} 100 {\AA}/Co_{71}Fe_{29} 40 {\AA}/Al-O$ junction with $d_{Al}= 8 {\AA} and P_{O2}{\times}t_{0X}/ = 8.4 {\times} 10^4$ at various temperatures. The current histogram statistically calculated from the electrical current image was well in accord with the fitting result considering the Gaussian distribution and Fowler-Nordheim equation. After annealing at $340^{\circ}C$, where the TMR ratio of the corresponding MTJ had the maximum value of 44%, the average barrier height increased to 1.12 eV and its standard deviation decreased to 0.1 eV. The increase of TMR ratio after annealing could be well explained by the enhancement of the average barrier height and the reduction of its fluctuation.

Comparative Analysis of Track-Bridge Interaction of Sliding Slab Track and Rail Expansion Joint for Long-Span Railway Bridge (장경간 철도 교량에 적용된 슬라이딩 궤도와 레일신축이음장치의 궤도-교량 상호작용 비교)

  • Lee, Kyoung Chan;Jang, Seung Yup;Lee, Jungwhee;Choi, Hyun Sung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.2
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    • pp.169-177
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    • 2016
  • Sliding slab track system, which consists of low friction sliding layer between track slab and bridge deck, is recently devised to reduce track-bridge interaction effect of continuously welded rail(CWR) without applying special devices such as rail expansion joint(REJ). In this study, a series of track-bridge interaction analyses of a long-span bridge with sliding slab track and REJ are performed respectively and the results are compared. The bridge model includes PSC box girder bridge with 9 continuous spans, and steel-concrete composite girder bridge with 2 continuous spans. The total length of the bridge model is 1,205m, and the maximum spacing between the two fixed supports is 825m. Analyses results showed that the sliding slab track system is highly effective on interaction reduction since lower rail additional axial stress is resulted than REJ application. Additionally, horizontal reaction forces in fixed supports were also reduced compared to the results of REJ application. However, higher slab axial forces were developed in the sliding slab track due to the temperature load. Therefore, track slab section of the sliding slab track system should be carefully designed against slab axial forces.

Correlation between a Soil Respiration and Environmental Factors, Air Temperature and Precipitation in Pinus densiflora Community in Namsan and Meaning on an Urban Forest Management (남산 소나무군락의 토양호흡과 환경요인인 기온과 강수량과의 상호관계 및 도시림 관리의 의미)

  • Lee, EungPill;Lee, SooIn;Park, JaeHoon;Kim, EuiJoo;Hong, YoungSik;Lee, SeungYeon;You, YoungHan
    • Journal of Korean Society of Forest Science
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    • v.109 no.2
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    • pp.136-144
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    • 2020
  • To prepare the management plan for reduction of the organic carbon emission caused by soil respirations, the amount of organic carbon emission from the pedosphere in Pinus densiflora community within metropolis park was quantified and then the correlations between quantified values and climate factors were analyzed. To this study, we investigated the amount of emitted organic carbon through soil respirations of Pinus densiflora community within Mt. Nam in Seoul-si, Korea, and identified correlationship with environmental factors. As a result, the average amount of organic carbons, included in soil respirations of P. densiflora community in Mt. Nam, was 7.978 ton C ha-1 yr-1. Also, precipitation of spring (March to May) was one of the environmental factors explaining the increase and decrease of soil respiration. This results suggest a drainage management to keep the low water content in understorey soils is important to an ecological management of metropolitan forests.

Characteristics of Low Dielectric Constant SiOF Thin Films with Post Plasma Treatment Time (플라즈마 후처리 시간에 따른 저유전율 SiOF 박막의 특성)

  • Lee, Seok Hyeong;Park, Jong Wan
    • Journal of the Korean Vacuum Society
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    • v.7 no.3
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    • pp.267-267
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    • 1998
  • The fluorine doped silicon oxide (SiOF) intermetal dielectric (IMD) films have been of interest due to their lower dielectric constant and compatibility with existing process tools. However instability issues related to bond and increasing dielectric constant to water absorption when the SiOF films was exposured to atmospheric ambient. Therefore, the purpose of this research is to study the effect of post oxygen plasma treatment on the resistance of moisture absorption and reliability of SiOF film. Improvement of moisture absorption resistance of SiOF film is due to the forming of thin SiO₂layer at the SiOF film surface. It is thought that the main effect of the improvement of moisture absorption resistance was densification of the top layer and reduction in the number of Si-F bonds that tend to associate with OH bonds. However, the dielectric constant was increased when plasma treatment time is above 5 min. In this study, therefore, it is thought that the proper plasma treatment time is 3 min when plasma treatment condition is 700 W of microwave power, 3 mTorr of process pressure and 300℃ of substrate temperature.

W 도핑된 ZnO 박막을 이용한 저항 변화 메모리 특성 연구

  • Park, So-Yeon;Song, Min-Yeong;Hong, Seok-Man;Kim, Hui-Dong;An, Ho-Myeong;Kim, Tae-Geun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.410-410
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    • 2013
  • Next-generation nonvolatile memory (NVM) has attracted increasing attention about emerging NVMs such as ferroelectric random access memory, phase-change random access memory, magnetic random access memory and resistance random access memory (RRAM). Previous studies have demonstrated that RRAM is promising because of its excellent properties, including simple structure, high speed and high density integration. Many research groups have reported a lot of metal oxides as resistive materials like TiO2, NiO, SrTiO3 and ZnO [1]. Among them, the ZnO-based film is one of the most promising materials for RRAM because of its good switching characteristics, reliability and high transparency [2]. However, in many studies about ZnO-based RRAMs, there was a problem to get lower current level for reducing the operating power dissipation and improving the device reliability such an endurance and an retention time of memory devices. Thus in this paper, we investigated that highly reproducible bipolar resistive switching characteristics of W doped ZnO RRAM device and it showed low resistive switching current level and large ON/OFF ratio. This may be caused by the interdiffusion of the W atoms in the ZnO film, whch serves as dopants, and leakage current would rise resulting in the lowering of current level [3]. In this work, a ZnO film and W doped ZnO film were fabricated on a Si substrate using RF magnetron sputtering from ZnO and W targets at room temperature with Ar gas ambient, and compared their current levels. Compared with the conventional ZnO-based RRAM, the W doped ZnO ReRAM device shows the reduction of reset current from ~$10^{-6}$ A to ~$10^{-9}$ A and large ON/OFF ratio of ~$10^3$ along with self-rectifying characteristic as shown in Fig. 1. In addition, we observed good endurance of $10^3$ times and retention time of $10^4$ s in the W doped ZnO ReRAM device. With this advantageous characteristics, W doped ZnO thin film device is a promising candidates for CMOS compatible and high-density RRAM devices.

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