• Title/Summary/Keyword: 증발 속도

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Preparation and Characterization of Zaltoprofen-Loaded Polyoxalate Microspheres for Control Release (방출제어를 위한 잘토프로펜이 함유된 폴리옥살레이트 미립구의 제조와 특성)

  • Kim, Kyoung Hee;Lee, Cheon Jung;Jo, Sun A;Lee, Jung Hwan;Jang, Ji Eun;Lee, Dongwon;Kwon, Soon Yong;Chung, Jin Wha;Khang, Gilson
    • Polymer(Korea)
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    • v.37 no.6
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    • pp.702-710
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    • 2013
  • Zaltoprofen loaded polyoxalate (POX) microspheres were prepared by an emulsion solvent-evaporation/extraction method like oil-in-water (O/W) for sustained release of zaltoprofen. The influence of several preparation parameters such as fabrication temperature, stirring speed, intensity of the sonication, initial drug ratio, molecular weight ($M_w$) of POX, concentration of POX and concentration of emulsifier has been investigated on the zaltoprofen release profiles. Physicochemical properties and morphology of zaltoprofen loaded POX microspheres were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and Fourier transform infrared (FTIR). Through the analyzed results, it was demonstrated that the characteristics of the microspheres greatly affected by the prepared condition. The releases behavior of zaltoprofen was investigated for 10 days in vitro. It was confirmed that the release behavior of zaltoprofen can be controlled by the manufacturing factor of solvent-evaporation/extraction method.

동시 스퍼터링 방법에 의한 Cu-In 금속층 증착 및 저온 안정상에 대한 열역학적 고찰

  • 김상덕;김수길;김형준;윤경훈;송진수
    • Proceedings of the Korean Vacuum Society Conference
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    • 2000.02a
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    • pp.129-129
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    • 2000
  • 태양전지는 태양광에너지를 바로 전기에너지로 전환시키는 소자이다. 최근에는 다결정 태양전지의 응용가능성에 대한 연구가 활발히 진행되어 오고 있다. 이 중 CuInSe2는 여러 가지 좋은 물성을 가지고 있어서, 저가의 고효율 태양전지를 위한 광흡수층 재료로 주목받고 있다. 현재까지 다양한 방법이 시도되었지만, 10% 이상의 고효율을 가지는 고품질을 박막을 얻는 방법은 진공증발증착법과 selenization 방법뿐이다. 이 중 진공증발증착법에 의하여 형성된 박막을 이용하여 가장 높은 효율의 태양전지를 얻을 수 있으나, 진공 장비의 대면적화가 힘들기 때문에 대면적 태양전지 제조가 힘들다는 단점이 있다. 따라서 selenization 방법을 이용하여 CuInSe2 박막을 제조하는 것이 가장 유망한 방법이라 할 수 있다. Selenization 방법은 Cu-In 금속층을 제작한 뒤 이를 selenium과 반응을 시키는 방법이다. 따라서 이 방법을 이용하여 박막을 제조할 때는 Cu-In 금속층의 물성 조절이 이후 생성되는 CuInSe2 박막의 물성향상에 필수적이다. 따라서 Cu-In 금속층의 물성에 대해 많은 연구가 이루어지고 있다. 하지만 Cu-In 이 성분계에서 알려진 반가 없다. 저온에서는 반응속도론적으로 매우 느리게 반응이 일어나기 때문에 열역학적으로 안정한 상을 얻기가 힘들기 때문이다. 따라서 본 실험에 앞서 각 제조 조건에 따른 열역학적인 안정상을 계산하였다. 그 결과, 상온에서 Cu의 양이 증가함에 따라, In$\longrightarrow$CuIn2$\longrightarrow$Cu11In9$\longrightarrow$Cu7In3 상으로 변화하였다. 9$0^{\circ}C$이하의 온도에서는 CuIn2 상이 안정하였고, 10$0^{\circ}C$ 이상의 온도에서는 Cu11In9 상 두 가지로 존재하였고, Cu/In 인가전력비를 변화시켰을 때 조성비가 선형적으로 변하였다. 즉, Cu-In 동시스퍼터링법은 원하는 조성을 간편한 방법으로 정확하게 조절할 수 있는 방법이라 할 수 있다. 증착 온도를 변화시켰을 때는 9$0^{\circ}C$ 이하의 낮은 온도에서 존재하던 CuIn2 상이 10$0^{\circ}C$이상의 온도에서는 완전히 사라지고 In과 CuIn2 상이 사라지고 In 상과 Cu11In9 상이 나타났다. 상전이를 위하여 30$0^{\circ}C$의 높은 열처리 온도가 필요한 것은, 밀 저온 안정상이 형성된 뒤 각 원소들의 확산에 의해 상전이가 일어나기 때문에 이를 위한 충분한 열에너지를 가질 수 있는 온도가 필요하기 때문이다. 조성을 일정하게 유지하면서 챔버 압력을 변화시켰을 때는 형성되는 상의 미세구조난 결정성은 일정하였다. 인가전력, 증착온도, 챔버 압력 변화에 따른 상변화는 앞서 계산한 열역학적 결과와 정확히 일치하였다. 이는 동시스퍼터링 방법이 각 입자들을 원소 단위에서 균일하게 혼합할 수 잇는 방법이고, 또 입자들이 높은 에너지를 가지고 있기 때문이다. 즉, 원소 단위에서 균일한 반응을 하고, 가장 안정한 위치로 쉽게 이동할 수 있기 때문에 열역학적으로 안정한 상을 형성할 수 있는 것이다.

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Distribution Behavior of Natural Radionuclide Pb in Molten Fe to Metal/Slag/Gas Phase (용융 Fe 중 천연방사성핵종 Pb의 금속/슬래그/가스상으로의 분배거동)

  • So-Yeong Lee;Hyeon-Soo Kim;Jong-Hyeon Lee;Ho-Sang Sohn
    • Resources Recycling
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    • v.33 no.2
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    • pp.54-61
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    • 2024
  • When steel contaminated with Pb, produced by the decay of natural radionuclides, is remelted, Pb distributes among the metal, slag, and gas phases. In this study, 5 wt%Pb was added to Fe and melted with CaO-SiO2-Al2O3-MgO slag to investigate Pb's distribution in the metal/slag/gas. As slag basicity ((wt%CaO)/(wt%SiO2)) increased, Pb solubility in Fe slightly increased, while Pb in the slag tended to decrease. Consequently, the slag/metal distribution ratio of Pb decreased with increasing basicity. Thermodynamic calculations revealed that the slag/Fe phase distribution ratio of Pb remained very low irrespective of the activity coefficient of PbO in the slag, consistent with the experimental results. The calculated evaporation rate of Pb in Fe-Pb was approximately 22 times that of Fe; hence, most of the Pb evaporated into the gas phase.

동축형 분사기 분무특성 및 연소의 이론적 모델

  • 원영덕;윤웅섭;김영수;윤경택
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2000.04a
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    • pp.4-4
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    • 2000
  • 일반적인 액체추진제 로켓엔진의 연소는 분사제트의 미립화, 액적의 증발, 기상 추진제의 혼합, 화학반응 등, 일련의 물리적 과정들로 이루어지고, 여기서 특성속도 효율은 크게 분사특성 및 연소의 두 단계에서 결정되게 된다. 액체추진제 로켓엔진에 사용되는 여러 분무형태 중, 동축형 분사기에서는 액상과 기상 제트의 운동량 차에 의해 미립화가 이루어지며, 분무 액적들의 전개와 더불어 분사기 출구를 포함한 전 영역에서 연소가 발생되므로 매우 복잡한 물리적 특성들을 포함하게 된다. 본 연구에서는 기상 연료-액상 산화제의 동축형 분무연소를 JANNAF의 방법을 사용하여 수식화 하였으며, 이를 바탕으로 분무특성과 연소성능 예측을 위한 프로그램을 작성, 분사조건에 의한 분무특성과 그에 따른 연소성능을 계산하였다. 연속, 운동량, 에너지 및 혼합비 방정식의 지배방정식들을 바탕으로 기상 유동을 수식화 하였으며, 별도로 액적의 소산 및 연소과정을 모사하기 위한 별도의 수식들이 추가되었고, 이 식들을 결합하여 액적의 크기, 분포를 포함하는 액체 제트의 미립화 정도를 공간적으로 계산하였다. 미립화 모델의 검증을 위하여 계산 결과를 Reitz의 실험과 Giridharan의 모델 등과 비교하였으며 잘 일치하는 경향을 나타내었다. 또한 동축형 분사기에서의 분무 특성을 예측하기 위해 액체 산소, 기체 수소를 추진제 조합으로 하는 동축형 분무 연소장에서의 제트 길이, 액적의 크기, 액체 제트의 속도를 계산하였다. 계산 결과 액체 제트의 접촉길이는 분사공의 지름이 증가할수록 웨버수가 증가되므로 짧아지는 것으로 관찰되었으며 액적의 크기도 분사공의 지름이 증가할수록 작아지는 경향을 나타내었다. 액체 제트의 속도는 처음에는 일정하게 유지되다가 운동량을 보존하기 위해 가스로부터 운동량을 받아 점차 가속되어지는 것으로 나타났다.본 규격은 키, 총장, 어깨길이, 등길이, 머리길이, 머리둘레, 진동둘레, 목둘레, 가슴둘레, 허리둘레, 배둘레, 엉덩이둘레, 앞품, 뒤품, drop치를 포함하고 있고, 각 규격에서 호칭간 치수 간격도 함께 제시하고 있다. 본 연구 결과에서 보듯, 현행 8규격의 무진복의 각 호칭간 적정 허용범위를 고려해 합리적인 치수체계를 정립한다면 치수에 대한 적합도가 상당히 증가할 뿐 아니라 생산비용도 상당히 감축할 것으로 생각된다.나타났다. 4) 호감적 서비스능력 차원에서 세 독립변수간에 유의한 3원 상호작용이 존재하는 것으로 나타나( $F_{2,228}$=15.62, P<.001) 20대에 적합한 의복 착용시( $F_{2,228}$=3.98, P<.05)와 60대에 적합한 의복 착용시( $F_{2,228}$=16.55, P<.001) 점포유형과 격식차림간에는 유의한 상호작용이 존재하는 것으로 나타났다. 5) 호감을 구성하는 세 요인들이 구매의도에 미치는 영향을 조사한 결과 호감적 인상차원은 29%(P<.001), 호감적 서비스능력차원은 6%(P<.001)의 구매의도를 설명해 주는 것으로 나타났다. 본 연구결과 노년 소비자에게 호감을 주는 판매원의 외모는 구매의도에 영향을 주어 실버의류산업의 이익증대와 밀접한 연관을 갖는 서비스품질의 중요한 요인으로 밝혀졌다.중요한 요인으로 밝혀졌다.로운 단백질 EPSPS가 다른 여러 식물에 이미 존재하고 있는 단백질로서 우리가 이미 이러한 식품을 섭취할 때 이 단백질도 같이 섭취해오고 있었다는 점, 둘째. 이 단백질이 소화액 분해 실험에서 짧은 시간내에 분해가 되었다는 점, 셋째. 재조합 된 콩과 자연 콩이 성분 분석에서 차이를 나타내지 않았다는 점, 네 번째. 쥐를 통한 다양섭취 실험에서 아무런 이상 반응이 없었

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Engineering Approach to Crop Production in Space (우주에서 작물 생산을 위한 공학적 접근)

  • Kim Yong-Hyeon
    • Journal of Bio-Environment Control
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    • v.14 no.3
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    • pp.218-231
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    • 2005
  • This paper reviews the engineering approach needed to support humans during their long-term missions in space. This approach includes closed plant production systems under microgravity or low pressure, mass recycling, air revitalization, water purification, waste management, elimination of trace contaminants, lighting, and nutrient delivery systems in controlled ecological life support system (CELSS). Requirements of crops f3r space use are high production, edibility, digestibility, many culinary uses, capability of automation, short stems, and high transpiration. Low pressure on Mars is considered to be a major obstacle for the design of greenhouses fer crop production. However interest in Mars inflatable greenhouse applicable to planetary surface has increased. Structure, internal pressure, material, method of lighting, and shielding are principal design parameters for the inflatable greenhouse. The inflatable greenhouse operating at low pressure can reduce the structural mass and atmosphere leakage rate. Plants growing at reduced pressure show an increasing transpiration rates and a high water loss. Vapor pressure increases as moisture is added to the air through transpiration or evaporation from leaks in the hydroponic system. Fluctuations in vapor pressure will significantly influence total pressure in a closed system. Thus hydroponic systems should be as tight as possible to reduce the quantity of water that evaporates from leaks. And the environmental control system to maintain high relative humidity at low pressure should be developed. The essence of technologies associated with CELSS can support human lift even at extremely harsh conditions such as in deserts, polar regions, and under the ocean on Earth as well as in space.

Flame Instability in Heptane Pool Fires Near Extinction (소화근처 헵탄 풀화재의 화염불안정성)

  • Jeong, Tae Hee;Lee, Eui Ju
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.12
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    • pp.1193-1199
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    • 2012
  • A cup burner experiment was performed to investigate the effect of the oxidizer velocity and concentration on flame instability near extinction. Heptane was used as a fuel and air diluted by nitrogen and carbon dioxide was used in the oxidizer stream. Two types of flame instabilities at the flame base and at axial downstream were observed near extinction. The instability at the flame base could be characterized by cell, swing, and rotation modes, and the cell mode changed to the rotation mode through the swing mode as the oxidizer velocity increased. To assess the parameters for the flame instability, the initial mixture strengths, Lewis number, and adiabatic flame temperature were investigated under each condition. The Lewis number might be the most important among them, but it is impossible to generalize because of the insufficient number of cases. Furthermore, the axial periodic flickering motion disappeared at low and high oxidizer velocities near extinction. This resulted from the fact that low oxidizer velocity induced evaporated fuel velocity below the critical velocity and high velocity made the reacting fuel velocity comparable.

A study for High Efficiency Dewatering of Sludge Contained Fine Particles (미세입자(微細粒子)를 함유(含有)한 슬러지의 고효율(高效率) 탈수(脫水) 연구)

  • Lee, Jung-Eun;Lee, Jae-Keun
    • Resources Recycling
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    • v.15 no.4 s.72
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    • pp.36-43
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    • 2006
  • There was some difficulty dewatering properties due to small porosity diameter of cake, when pigment sludge contained fine particle was formed by cake under the dewatering. It was difficult to dewater the sludge with fine particles with the conventional mechanical dewatering method. This study was to improve the dewatering rate as discharging the water from porosity of cake easily, supplying the low heat to the cake layer. Thermal dewatering equipment of piston type to keep up constant temperature on the cake was set up and relative experiment was conducted for sludge of 200 g with fine pigment particle. As test results. filtration of 176.8 g, cake weight of 19.4 g, cake thickness of 4.2 mm was measured, and it was analyzed that the water content of cake was 47 wt% and dewatering velocity, which moaned the residual d교 sloid amount per dewatering area, was $2.1DS\;m^{2}{\cdot}cycle$. This results showed that filtration increased, cake weight and thickness decreased and dewatering velocity increased against mechanical dewatering method. And water content of cake decreased about 30%, so the result which dewatering rate improved was drew generally. The reason is that the inner vapor pressure working at the cake porosity increased as applying the low heat to the cake layer, which lead to discharge the water from porosity easily. Therefore, this study was estimated by the useful technology for sludge reduction.

A study on the manufacture of humidity sensors using layered silicate nanocomposite materials (층상 실리케이트계 나노복합 소재 적용 습도센서 제조에 관한 연구)

  • Park, Byoung-Ki
    • Industry Promotion Research
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    • v.9 no.1
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    • pp.31-38
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    • 2024
  • In this study, evaluated the properties of layered silicate-based nanocomposite sensitive film. For the fabrication of nanocomposite materials, we selected organically modified layered silicate materials, specifically Cloisite® and Bentone®, which were treated with quaternary ammonium salts. The impedance of the humidity sensors containing organically modified montmorillonite/hectorite clay decreased with increasing relative humidity(RH%). In the case of the Cloisite® humidity sensor exhibited slightly better impedance linearity and hysteresis compared to the Bentone® 38 humidity sensor. Additionally the impedance of the sensor with Bentone® 38 addition was the lowest when compared to the Cloisite®-modified sensor. Comparing the Cloisite®-modified sensors individually, we observed different moisture absorption characteristics based on the hydrophilic properties of the organic-treated materials. The response speed of Cloisite® 93A tended to be slower due to differences in moisture evaporation rates influenced by the hydrophilic organic components. Based on these results, moisture barriers utilizing organically modified layered silicate materials may exhibit slightly lower moisture absorption properties compared to conventional polymer-based moisture barriers. However, their excellent stability, simple processing, and cost-effectiveness make them suitable for humidity sensor applications.

A Study on the optimum drying condition of sewage sludge cake using continuous microwave full scale dryer (연속적 마이크로파 Full Scale 건조장치를 이용한 하수슬러지 케익의 최적 건조조건 연구)

  • Ha, Sang-An;Jung, Wang-Seok
    • Journal of the Korea Organic Resources Recycling Association
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    • v.16 no.2
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    • pp.47-56
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    • 2008
  • The objective of this research is to evaluate the optimum recycling methods for the sewage sludge cakes at different microwave power-settings and for different periods of time. The dehydrated sewage sludge cakes used in this study was obtained from N wastewater treatment plan in the P City. The beginning drying processes were carried out in a microwave oven with 2,450 MHz frequency and power ranges of 1kW to 4 kW. The continuous conveyer drying system was also operated with 2,450 MHz frequency and power setting, ranging from of 1 kW to 6 kW. Initial moisture content of the sewage cake is 78~80%, and the moisture content decreased rapidly up to 0.2~2(wt%) within short periods due to breaking the cell walls. This study is also conducted to evaluate the characteristics of sewage sludge cakes with respect to important physical parameters effect on the thermal kinetics for evaporation water in the sludge which are operation times, moisture contents, drying rates, input amounts, flow rates and calorific values. It takes 60 minutes and 120 minutes to reach the critical moisture contents with power setting of 4 kW for 3kg/min and 6kg/min of the flow rates respectively. It takes 120 minutes and 110 minutes to reach the critical moisture contents with flow rates of 2.5 cm/min and sludge input of 6kg/min for the power settings of 4 kW and 6 kW respectively. The most effective value of the power for drying the sludge is 4 kW. Operation with 6kg/min and 4kW on 2cm of the sludge thickness can be effectively and inexpensively to reach the critical moisture contents, when you compare 2cm of the sludge thickness with 1cm and 3cm of the sludge thickness.

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Meteorological Element and Vegetative Structure for Sorbus commixta Hedl. Natural Populations at Ulleung Island (울릉도 마가목 천연집단의 기상인자 추정 및 식생구조)

  • 김세현;장용석;정헌관;최영철
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.5 no.3
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    • pp.158-165
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    • 2003
  • This study was conducted to reveal the role of meteorological elements on the habitat characteristics and vegetative structure for S. commixta natural populations at Ulleung Island. Potential Evapotranspiration(PET) by elevation of Ulleung Island was estimated using Thornthwaite's climatology estimating method. Also, Warm Index (WI), Coldness Index (CI) and vegetative composition by elevation were determined. The following results were obtained: The S. commixta trees wire mainly distributed from an elevation of 300 m to 900 m. The WI and CI were about 66.8∼95.0, -21.5∼-7.7, respectively. Water deficit by precipitation and Potential Evapotranspiration (PET) mainly occurred from March to October at all elevations. But wafer deficits diminished with increased elevation. The apparent species in S. commixta natural populations at Ulleung Island were: 10 tree layer species, 17 subtree layer species, and 25 species in the shrub layer. In the tree layer, S. commixta was dominant with the highest value of 46.85, then Fagus crenate 13.43, Acer mono and Tilia amurensis 12.41 and 12.03, respectively. In the subtree layer, A. mono was dominant with the highest value of 13.16, then F. crenata 12.68, Acer pseudo-sieboldianum and S. commixta 11.37 and 10.76, respectively. Dominant species and IV values in the shrub layer were Sasa borealis (22.09) and Rhododendron brachycarpum (10.51). The S. commixta natural forests were in a relatively stable rendition because of the even distribution of its various indexes: the species diversity index of Shannon, the evenness index and dominance were 0.6199∼1.1390, 0.6199∼0.8825 and 0.1852∼0.3801, respectively.