• 대한수학회보
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• 제52권6호
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• pp.1839-1854
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• 2015

Brief developments in metrical fixed point theory are covered and a significant generalization of recent results obtained in [18], [27], [32] and [33] is established through an extension of the property (EA) to two sequences of self-maps using the notions of weak compatibility and implicit relation.

• Computers and Concrete
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• 제7권6호
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• pp.497-510
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• 2010

For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1564-1566
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• 2004

BCP의 이온화에너지 (Ionization Potential; IP)는 5.72ev와 전자친화도 (Electron Affinity; EA)는 2.85ev이며, PEDOT의 IP=5.74ev와 EA=3.3sev이고, TAZ의 IP=6.45ev와 EA=2.77ev, TPD는 IP=5.75ev와 EA=2.S8eV를 나타내었다. 그리고 BCP와 TAZ는 산화전위의 시작점과 증가곡선의 전위 변곡점과의 차이(정공층 갭)와 환원전위의 시작점과 변곡점의 차이(전자층 갭)가 서로 비슷하였으며, PEDOT과 TPD의 경우 정공층의 갭이 전자층의 갭보다 크게 나타났다.

• 한국화재소방학회논문지
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• 제16권3호
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• pp.16-25
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• 2002

소화제인 Freon-23과 몬트리올 의정서에 의해서 규제받는 CFC의 대체 물질인 HFC-227ea의 물성(포화압력, 밀도, 점도, 엔탈피, 표면장력)에 관한 실험식을 구하였다. 문헌에서 얻은 실험값을 이용하여 다항식등의 회귀분석에 의해서 실험식을 얻었다. 포화압력은 온도에 대하여 각각 3차와 2차의 실험식으로 표시하였다. 압축인자와 포화압력을 이용하여 온도에 대한 밀도에 관한 실험식을 제시하였다. 점도는 온도에 대한 지수함수로 표시하였고, 엔탈피는 열용량과 마찬가지로 온도에 대한 2차 함수로 정의하여 나타내었다. 표면장력에 대해서는 간단한 1차 온도에 대한 선형적인 관계가 있었다.

• 한국표면공학회지
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• 제56권2호
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• pp.152-159
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• 2023

The night visibility of pavement is being considered as a global issue in the field of traffic safety. Although the spreading glass beads on the lane paints has been mainly used to secure night-visibility by utilizing the effect of retroreflection, obvious shortcoming of this method is that retroflection does not occur in the range where the headlights do not reach the glass beads. The use of functional paints including phosphorescent constituents could be a solution for overcoming fore-mentioned problem. SrAl₂O₄ based chemicals have not only good phosphorescent property, but also are chemically stable compared to existing ZnS based materials. However, this chemicals also need the improvement due to slightly reduced luminous effect in time. Herein, we developed novel paints showing enhanced phosphorescent properties by putting rare earth elements such as Eu, Dy and Y into SrAl₂O₄. These prepared phosphorescent pigments have displayed improved properties in terms of durability and long afterglow. For instance, the property of afterglow has been persisted after 5 hours with luminace of 20.6 mcd/m².

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.61-64
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• 2006

Comparing with traditional high performance concrete, ultra high performance concrete (UHPC) has the property of high-tenacity. However, drying shrinkage and autogenous shrinkage can be arisen as the major defect to UHPC. In this study, therefore, it was tested to reduce drying shrinkage and autogeneous shrinkage by adding expanding admixture (EA) and shrinkage reducing agent (SRA). As a result, for a case drying shrinkage, the shrinkage was decreased by 94% when EA was exchanged, and it was decreased by 64% when SRA was added. For the case of autogenous shrinkage, the mortar was expanded at early age and the shrinkage was decreased by 87% when EA was exchanged, and the shrinkage was decreased by 70% when SRA was added.

• 대한한방소아과학회지
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• 제35권1호
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• pp.76-103
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• 2021

Objectives This study was designed to examine the effect of Gleditsiae Fructus n-hexane (GSF_Hx) on two different groups (on the LPS-induced activation of Raw264.7 cells in vitro, and on the DNCB-induced activation of atopic dermatitis NC/Nga Tnd mice in vivo) to find index components and active components of Gleditsiae Fructus. Methods GSF_Hx was analyzed by HPLC profiling and confirmed echinocystic acid (EA), oleanolic acid (OA) as index components of Gleditsiae Fructus. Using GSF_Hx, EA, OA, we investigated IL-6, TNF-α, NO production by ELISA analysis and evaluated manifestations of MAPKs transcription factors and NF-κB p65 translocation by western blotting. During In vivo study, atopic dermatitis was induced on NC/Nga Tnd mice by DNCB and administered GSF_Hx, EA, OA orally, and checked skin lesions and measured skin clinical score. Serum IgE level, Th1 and Th2 cytokines secretion and modulating molecular mediators and immune cells in the spleenocyte culture supernatant, PBMCs, ALN and dorsal skin were also measured by real-time PCR. Then, skin rash was evaluated and mast cell distribution was verified by H&E and toluidine blue staining on dorsal skin. Results It is possible that GSF_Hx, EA and OA reduce inflammation and allergic response of atopic dermatitis by suppressing Th1 and Th2 cytokines secretion and modulating molecular mediators and immune cells. They also had moisturizing effect by raising vitality of ceramide in dorsal skin of atopic dermatitis NC/Nga Tnd mice. However, EA particularly had better overall activity data than OA, that EA could be a more effective active component of Gleditsiae Fructus than OA. Conclusions Based on the inflammatory reduction property with moisturizing effect, GSF_Hx may play a role in effective treatment for atopic dermatitis.

• Journal of Acupuncture Research
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• 제24권5호
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• pp.105-111
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• 2007

Objectives : The electroacupuncture(EA) was often used in Oriental medicine clinic and basic researches. However, there have been neither any national standard of acupuncture needles in Korea nor many studies about the property of acupuncture needles for applying electrical stimulations. Therefore we investigated the electrical corrosion property of acupuncture needles used for EA stimulation in clinic. Methods : We observed the occurrence of electrical corrosion like changes in the surface of acupuncture needles after EA stimulation with various parameters(electrical stimulation intensity, treatment duration, diameter of needle) under a light microscope. We performed EA stimulation on Baekhoe($GV_{20}$) or Joksamli($ST_{36}$) of rats with intensity of 0.025, 0.05, 0.075, 0.1, 0.25 or 0.5mA at a 10Hz frequency. Results : The electrical corrosion-like changes were found on the surface of needles when the EA stimulation was given over 0.05mA of intensity. When electrical stimulation was treated for 10min, the electrical corrosion-like changes were low, but the electrical corrosion-like changes gradually increased by the treatment duration(20, 30min). We also found that acupuncture needles of 0.2mm diameter were produced more extensive electrical corrosion-like changes than acupuncture needles of 0.3 or 0.4mm diameter by electrical stimulation. Conclusions: These results suggested that EA stimulation could produce electrical corrosion-like changes of acupuncture needles through intensity of current, duration of electric stimulation and/or diameter of needle.

• 접착 및 계면
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• 제15권3호
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• pp.116-122
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• 2014

자외선 경화법을 이용한 강판의 표면 코팅 시 사용되는 올리고머, 단량체, 광개시제 및 강판의 특성 등 주요 인자가 코팅 표면의 $20^{\circ}$ 및 $60^{\circ}$ 광택도(ASTM D523)에 미치는 영향에 대해서 연구하였다. 공정 변수에 대한 광택도의 변화는 $60^{\circ}$ 광택도에 비해 $20^{\circ}$ 광택도가 민감하게 변화하였다. 단독으로 올리고머를 사용할 경우의 경우, 광택도의 변화는 거의 없었으나, 올리고머의 혼합 비율이, 단량체의 종류와 혼합 비율, 올리고머와 단량체의 혼합 비율, 개시제의 종류와 함량 비, 강판의 종류는 광택도에 큰 영향을 주었다. 올리고머 혼합의 경우 폴리우레탄 아크릴레이트(UA)와 에폭시 아크릴레이트(EA)의 혼합 비율이 70 : 30, 단량체의 경우 트리메틸올프로판트리아크릴레이트(TMPTA)와 테트라히드로퍼퍼릴아크릴레이트(THFA)가 5 : 5의 비율로 혼합된 경우가, 혼합 올리고머(UA : EA = 70 : 30)의 함량이 90 wt%인 경우 최대의 광택도를 나타내었다. 광개시제 중 액체 타입인 Darocur MBF가 고체 타입인 Irgacure 184에 비해 우수한 광택도를 나타내었으며, 최소 투입량인 1 wt%의 농도에서 높은 광택도를 나타내었다. 기질의 경우, EG강판이나 primer가 처리된 강판에 비해 GI강판이 더 좋은 광택도를 보여주었다. 상기 공정 변수에 대한 연구를 통해 광택도 향상을 위해 사용되는 첨가제 없이도 $20^{\circ}$ 광택도 95 GU의 최대값을 $60^{\circ}$ 광택도는 120 GU의 광택도를 얻을 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3270-3275
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• 2007

DME (Dimethyl Ether, $CH_3OCH_3$) has highly attracted attention as an alternative fuel for transportation, power generation and LPG substitute owing to its easy transportation and cleanliness. This study was conducted to verify the combustion performance and to identify potential problems when DME is fuelled to a gas turbine. GE7EA gas turbine of Pyong-Tak power plant was selected as a target to apply the DME. Combustion tests were conducted by comparing DME with methane, which is a major component of natural gas, in terms of combustion instability, $NO_X$ and CO emissions, and the outlet temperature of the combustion chamber. The results of the performance tests show that DME is very clean but has a low combustion efficiency in low load condition. From the results of the fuel nozzle temperature we have ascertained that DME is easy to flash back, and this property should be considered when operating a gas turbine and retrofitting a burner.