• 제목/요약/키워드: two-stage mixture analysis

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수직 패들형 및 하이드로 포일형 응집기 특성의 전산유체역학 해석 (CFD ANALYSIS ON THE CHARACTERISTICS FOR FLOCCULATORS OF VERTICAL PADDLE AND HYDRO-FOIL TYPE)

  • 신종현;장세명;조용
    • 한국전산유체공학회지
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    • 제21권3호
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    • pp.24-30
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    • 2016
  • In the water purification plant, the mixture of water and chemical from the mixing basin enters the flocculation basin. The rotating flocculators are generally used for the efficient flocculation of dregs. In this paper, the performance of flocculators of a vertical paddle type, widely used in the typical flocculation basins, and a hydro-foil type, recently disseminated in the field, are compared with each other by use of the numerical method. Also the characteristics and the efficiency are analyzed with CFD techniques. The strain rate and the eddy viscosity are compared for two types to predict the mixing efficiency, and the maximum speed and its location are pursued from the computed data. The hydrofoil type shows that the eddy viscosity is enhanced 1.66 to 3.03 times larger than that of vertical paddle type, and also produced 1.87 to 1.95 times larger flocs for each stage. However, the rapid rotation of hydrofoil may chop the floc to small size due to the higher turbulence intensity. From the result of computation, the strong and weak points of each type have been analyzed for the decision making.

랫드 유선 상피 세포의 분리와 gap junction 단백질의 발현 양상 (Characterization of rat mammary epithalial cells and expression of gap junctional proteins)

  • 서민수;강경선;이영순
    • 대한수의학회지
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    • 제43권4호
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    • pp.649-656
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    • 2003
  • We have a cultured method to grow rat mammary epithelial cells (RMEC) for 1 to 14 days in 1:1 mixture of Dulbecco's Modified Eagle Medium: Nutrient and F-12 (DMEM/F-12) containing 10% fetal bovine serum (FBS), human EGF, insulin, hydrocortisone, human transferrin and $17{\beta}$-estradiol in vitro. We were able to isolate and distinguish two cell types, luminal epithelial cells and myoepithelial cells, from primary clutures of RMEC. Immunocytochemical stains were used to distingusih luminal epithelial cells and myoepithelial cells. Peanut lectin (PNA) was stained in most alveolar epithelail cells and luminal epithelial cells of rats, while Thy-1.1, a maker of potential rat mammary myoepithelial cells, was expressed in myoepithelial cells in the rat. Also, we examined the expression patterns of three types of gap junction proteins, connexin 26 ($C{\times}26$), connexins 32 ($C{\times}32$) and connexin 43 ($C{\times}43$) by immunocytochemistry and western blot analysis. In the cell types, the results show that at the early stage of culture, luminal epithelial cells were increased and these cells were surrounded by myoepithelial cells. At the late stage of culture, luminal epithelial cells were decreased, in contrast myoepithelial cells were increased. In the expression pattern of gap junction, $C{\times}26$ maintained it's expression until day 3, but afterwards gradually decreased in intensity. Expression of $C{\times}32$ remained until day 5, then decreased slightly. $C{\times}43$ gradually increased untill the middle time of culture then decreased in intensity. These results suggest that connexins may be important for the control of growth in rat mammary epithelial cell types.

호남지방(湖南地方) 직파재배(直播栽培)의 현황(現況), 문제점(問題點) 및 대책(對策) - 잡초방제적(雜草防除的) 측면(側面)에서 - (The Status, Problems and Countermeasure of Direct Rice Seeding in Honam Province - On Weed control -)

  • 양환승;김종석
    • 한국잡초학회지
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    • 제12권3호
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    • pp.271-291
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    • 1992
  • 호남지방(湖南地方)에 있어서 직파재배(直播栽培)의 현황(現況)과 잡초방제(雜草防除)에 대한 문제점(問題點) 및 그 대책(對策)에 對(대)하여 조사연구(調査硏究)를 하였다. 호남지방(湖南地方)(전북(全北), 전남(全南), 충남(忠南) 및 광주시(光州市))에 있어서 92년(年) 현재(現在) 직파면적(直播面積)은 건답(乾畓)이 732.1ha 담수(湛水)가 918.7ha로 총(總)1,650ha 였다. 1. 건답직파(乾畓直播) 농가(農家)의 잡초방제(雜草防除) 현황(現況)을 보면 건답기간(乾畓期間)에는 파종(播種) 3-5일(日) 후(後)에 butachlor 유제(乳劑)나 입제(粒劑)를 처리(處理)하였으며 극(極)히 소수(少數)의 농가(農家)는 benthiocarb 나 chlornitrofen 유제(乳劑)도 사용(使用)하였다. 또 벼 발아전(發芽前) 10-14일(日) 후(後) butachlor에 praquat을 혼합(混合)(Tank Mixture) 하여 처리(處理)한 농가(農家)도 있었다. 그리고 이어서 파종(播種) 35~40 일(日) 사이 담수후(湛水後)에는 Sulfonyl-urea계(系) 합제(合劑)를 처리(處理)하는 체계처리(體系處理)를 택(擇)하고 있었고 상기(上記) 제초제(除草劑)를 처리(處理)하고도 방제(防除)되지 못한 잔초(殘草)는 Bentazon + quinclorac 수화제(水和劑)로 마무리 제초(除草)를 하고 있었다. 2. 대부분(大部分)의 농가(農家)는 담수직파(湛水直播)에 있어서 제초제처리(除草劑處理)를 할때는 각(各) 제초제(除草劑)에 대한 특성(特性)을 이해(理解)하지 못한 가운데 선택(選擇)을 했거나, 특히 제초제(除草劑)의 처리적기(處理適期)를 지나서 처리(處理)하여 실패(失敗)한 경우(境遇)가 많았다. 그 중(中) 제초제처리(除草劑處理)에 비교적(比較的) 성공(成功)한 농가(農家)의 사례(事例)는 다음 4종류(種類)로 요약(要約)된다. (1) 파종전(播種前) 처리(處理) : 파종(播種) 5-9 일(日) 前 써레질 직후(直後) oxadiazon, butachlor 또는 benthiocarb를 처리(處理)하고 이어서 파종(播種) 20일(日) 후(後)에 sulfonyl-urea계(系) 합제(合劑)를 처리(處理)한 체계처리(體系處理) (2) 써레질후(後) 10 일항(日項)에(피 2엽기(葉期) 이내(以內))에 bensulfuron-methyl + dimepiprate 또는 pyrazosulfuron-ethyl + Molinate, bensulfuron-methy1 + mefenacet + dymron 등을 처리(處理)한 체계(體系)(두 제초제(除草劑)는 초기(初期) 약간(若干)의 약해(藥害) - 그후(後) 회복(回復)) (3) 써레질 18-20 일(日) 후(後)(피 3.0 엽(葉))에 bensulfuron-methyl + quinclorac, Pyrazosulfuron-ethyl + quinclorac, bentazon + quinclorac 입제(粒劑) 등(等)의 처리(處理)는 약해(藥害)도 없고 제한효과(制限效果)도 우수(優秀)하여 성공적(成功的)이었다. 그러나 그외(外)의 sulfunyl-urea계(系) 합제중(合劑中) 중기처리(中期處理) 제초제(除草劑)는 피에 대한 방제효과防除效果)가 불완전(不完全)하여 바로 이어서 bentazon+quinclorac 수화제(水和劑)의 추가처리(追加處理)가 필수적(必須的)이었다. 3. 직파재배(直播栽培)에 있어서 엽기(葉期)가 진행(進行)된 피에 대하여 우수(優秀)한 살초효과(殺草效果)를 나타낸 quinclorac합제(合劑) 대신 대체(代替) 가능(可能)한 제초제(除草劑)를 찾고자 우리나라에 등록(登錄)된 41종(種)의 논 제초제(除草劑)를 화합물(化合物) 계통별(系統別)로 분류(分類)하고 각각(各各)의 특징(特徵)과 처리적기(處理適期)를 분석(分析)한 결과(結果) 초기처리(初期處理)가 약(約)70% 였으며 그 외(外)에는 중기(中期) 및 후기처리(後期處理) 제초제(除草劑)였다. 담수직파재배(湛水直播栽培)에서는 파종후( 播種後) 벼가 완전(完全)히 착근(着根)하고 뜬묘나 누은묘가 없는 시기(時期)에 제초제(除草劑)를 처리(處理)하는 것이 완전(完全)하다. 그런데 이때에는 피가 2.5- 3.0엽기(葉期) 이상(以上) 되므로 처리적기폭(處理適期幅)이 넓은 除草劑가 절실(切實)히 필요(必要)하다. 따라서 일년생(一年生) 및 다년생(多年生) 잡초(雜草)를 동시(同時)에 방제(防除)할 수 있는 sulfonyl-urea 계합제중(系合劑中) 중기처리제(中期處理劑) 6종(種)과 bentazon + quinclorac 합제(合劑) 2종(種)을 공시(供試)하여 피 3.0엽기(葉期) 이상(以上)에서 담수조건(湛水條件)에서는 토양처리(土壤處理) 그리고 건답조건(乾畓條件)에서는 경엽처리(莖葉處理)하여 피 엽기별(葉期別) 살초(殺草) 스펙트램을 검정(檢定) 실시(實施)하였다. 그 결과(結果)(Table 9, 10, 11) 살초폭(殺草幅)이 넓은 순위(順位)는 bentazon + quinclorac WP>bentazon+quinclorac G>Bensulfuron-methyl + quinclorac G>pyrazosulfuron-ethyl + quinclorac G>pyrazosulfuron-ethyl + Molinate>bensulfuron-methyl + mefenacet +dymron G>bensulfuron-methyl + mefenacet G>bensulfuron-methyl + benthiocarb G로 나타났으며 농가포장(農家圃場)에서 직면(直面)한 결과(結果)와도 부합(符合)된다. 결론적(結論的)으로 건답직파(乾畓直播) 담수직파(湛水直播)를 막론(莫論)하고 피 엽기(葉期)가 3.0엽기(葉期) 이상(以上)으로 진행(進行)된 상태(狀態)에서는 bentazon + quinclorac합제(合劑)를 대체(代替)할 제초제(除草劑)는 아직 없다. 따라서 직파재배(直播栽培) 정착(定着)을 위해서는 quinclorac합제(合劑)는 농가(農家) 공급(供給)이 지속(持續)되어져야 된다. 직파재배(直播栽培)의 조속(早速)한 정착(定着)을 위하여 다음 사항(事項)을 제안(提案)한다. 1. 관(官), 농민(農民), 연구지도기관(硏究指導機關)이 일절(一切)가 된 가칭(假稱) 직파재배시험(直播栽培試驗) 연구위원회(硏究委員會)를 지방별(地方別)로 조직운영(組織運營)할 것. 2. 정밀(精密)한 세조파기(細條播機) 및 직파전용(直播專用) 품종개발연구(品種開發硏究) 3. 새 피해(被害) 방지연구(防止硏究) 4. 잡초방제기술(雜草防除技術)의 체계확립(體系確立)에 대한 다면적연구(多面的硏究) 5. 토지기반조성(土地基盤組成) 확충(擴充)과 정밀(精密)한 정지작업(整地作業) 기술연구(技術硏究) 및 항공산파법(航空散播法) 연구(硏究).

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Computational Analysis of the Effects of Spray Parameters and Piston Shape on Syngas-Diesel Dual-Fuel Engine Combustion Process

  • Ali, Abubaker Ahmed M.M.;Kabbir, Ali;Kim, Changup;Lee, Yonggyu;Oh, Seungmook;Kim, Ki-seong
    • 한국분무공학회지
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    • 제23권4호
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    • pp.192-204
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    • 2018
  • In this study, a 3D CFD analysis method for the combustion process was established for a low calorific value syngas-diesel dual-fuel engine operating under very lean fuel-air mixture condition. Also, the accuracy of computational analysis was evaluated by comparing the experimental results with the computed ones. To simulate the combustion for the dual-fuel engine, a new dual-fuel chemical kinetics set was used that was constituted by merging two verified chemical kinetic sets: n-heptane (173 species) for diesel and Gri-mech 3.0 (53 species) for syngas. For dual-fuel mode operations, the early stage of combustion was dominated by the fuel burning inside or near the spray plume. After which, the flame propagated into the syngas in the piston bowl and then proceeded toward the syngas in the squish zone. With the baseline injection system and piston shape, a significant amount of unburned syngas was discharged. To solve this problem, effects of the injection parameters and piston shape on combustion characteristics were analyzed by calculation. The change in injection variables toward increasing the spray plume volume or the penetration length were effective to cause fast burning in the vicinity of TDC by widening the spatial distribution of diesel acting as a seed of auto-ignition. As a result, the unburned syngas fraction was reduced. Changing the piston shape with the shallow depth of the piston bowl and 20% squish area ratio had a significant effect on the combustion pattern and lessened the unburned syngas fraction by half.

화학반응수치해석을 이용한 HCCI기관의 예혼합기의 성층화성이 연소시의 압력 상승률에 미치는 영향 (Numerical Analysis of Effect of Inhomogeneous Pre-mixture on Pressure Rise Rate in HCCI Engine by Using Multizone Chemical Kinetics)

  • 임옥택
    • 대한기계학회논문집B
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    • 제34권5호
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    • pp.449-456
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    • 2010
  • HCCI 엔진은 고효율, 저공해를 실현할 수 있는 차세대 내연기관이다. 그러나 HCCI 엔진이 상용화되기 위해서는 몇 가지 문제점들이 해결되어야 한다. 그 중에서 가장 큰 문제점은 과도한 압력 상승률이 노킹을 발생시키기 때문에 운전영역이 제한되는 것이다. 이번 연구의 목적은 HCCI 엔진에서 압력상승률 저감을 위하여 온도 성층화와 농도 성층화 효과를 조사하는 것이다. 그리고 Multi-zone 모델을 이용한 화학반응 수치해석을 통하여 연소 및 배기가스 특성에 미치는 영향을 알아보았다. 수치해석에서 2 단계 열발생을 가지는 DME와 1단계 열발생을 가지는 메탄을 사용하였다.

Expression of transforming growth factor-1 in bone regeneration after the implantation of particulate dentin and plaster of Paris

  • Huh, Young-Chul;Kim, Su-Gwan;Kim, Jeong-Sun;Yoon, Jung-Hoon;Kim, Do-Kyung
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • 제32권1호
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    • pp.27-35
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    • 2006
  • Purpose: This study was performed to investigate the expression of the transforming growth factor (TGF)-1, in a rat calvarium defect model using particulate dentin and/or plaster of Paris, and correlate the bone regeneration process with the histologic events. Materials and Methods: Thirty-two Sprague-Dawley rats were divided into 4 groups of 8 animals each. A 1.0 cm-sized calvarial defects were made and the defect was filled with different graft materials as follows : Group A, the defects were filled with a mixture of particulate dentin and plaster of Paris with a 2:1 ratio; Group B, the defects were filled with plaster of Paris only; Group C, defects were filled with particulate dentin only; Group D, untreated control group. The animals were sacrificed by 1, 2, 4, 8 weeks after implantation. Excised wound tissues were processed for histology, immunohistochemistry and RT-PCR for the analysis of TGF-1 expression. Results: Gene expression of TGF-1 was detected for all experimental groups. The highest gene expression was observed in the specimen taken at the first week after implantation in Group A. According to the histologic and immunohistochemical studies, TGF-1 positive osteoblast-like cells were found in the early stage of healing after the implantation of particulate dentin and plaster of Paris. Conclusion: These findings suggest that TGF-1 may be related to new bone formation at the early healing process after the implantation of particulate dentin and plaster of Paris.

설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제26권12호
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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 fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (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 for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Air Jet Mill 공법과 PMMA의 단분산성이 프레스드 파우더의 밀착성 및 발림성 향상에 대한 연구 (A Study on the Improvement of Skin-affinity and Spreadability in the Pressed Powder using Air Jet Mill Process and Mono-dispersed PMMA)

  • 송상훈;홍경우;한종섭;김경섭;박선규
    • 대한화장품학회지
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    • 제43권1호
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    • pp.61-68
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    • 2017
  • 베이스메이크업 중의 하나인 프레스드 파우더는 주요 품질 속성으로 밀착성과 발림성이다. 일반적으로 메이크업 화장료에서 밀착성을 향상시키면 반대속성인 발림성이 저하되기 때문에 밀착성과 발림성을 동시에 충족시키는데 한계가 있었다. 본 연구에서는 두 가지 주요 속성을 만족시키기 위해서 air jet mill 공정을 시도하였고, lauroyl lysine (LL)과 sodium cocoyl glutamate (SCG)의 혼합물로 습식 코팅 처리한 sericite를 적용하여 밀착성을 향상시켰다. 또한, 분산성이 단분산성을 이루고 있는 polymethyl methacrylate (PMMA)와 diphenyl dimethicone/ vinyl diphenyl dimethicone/ silsesquioxane crosspolymer (DDVDDSC)를 적용하여 발림성을 향상시켜 서로 양립하기 어려운 두 가지 품질 속성을 모두 만족시켰다. air jet mill 공정은 제약, 식품 산업에서 주로 적용되고 있으며 화장품 분야에서는 파우더 소재 가공을 위해 사용되고 있는 공법이다. 본 연구에서는 air jet mill 공정을 제조 공정단계에서 접목시켜 최적의 입경인 $6.8{\mu}m$의 화장료를 완성할 수 있었다. 그리고, EDS 매핑으로 Ti 원소가 화장료에서 전체적으로 고르게 분포하고 있음을 확인하였고, SEM 분석을 통하여 판상 입자의 모서리 부분이 둥글게 가공처리 됨을 확인하였다. 이는 화장 도구를 이용하여 화장료를 취하여 피부에 도포할 때, 발림성이 향상되는 효과를 줄 수 있다고 판단된다. 피부 친화성이 우수한 LL과 저자극이면서 코코넛에서 유래한 SCG를 습식 코팅하여 sericite의 밀착성을 더욱 향상시켰다. 그리고, PMMA의 분산성과 형태가 발림성에 미치는 영향을 평가하기 위해서 SEM을 분석하였다. 유사한 형태를 갖는 구형 및 진구형에서도 분포도가 균일하고 단분산상일 때 발림성 효과가 더욱 증가하는 것으로 나타났다. PMMA의 단분산성과 입경에 따른 발림성을 동마찰계수 측정으로 확인하였고, 최적의 함량을 결정하였다. 그리고, 실리콘 러버 파우더 종류에 따른 발림성과 경도, 낙하안정성 등을 확인하여 DDVDDSC를 결정하였다. 최종적으로 PMMA의 단분산성과 실리콘 러버 파우더가 발림성에 영향을 끼치는 것을 알 수 있었다. 이와 같은 화장료는 적정한 경도를 갖으면서도 낙하안정성이 우수하며, 경시에 따른 안정성도 우수하였다. 본 연구 결과를 통해 본 논문에서 제시하는 프레스드 파우더의 밀착성과 발림성을 향상시킬 수 있는 한 가지 방법으로 활용될 수 있을 것이라 판단된다.