• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.209-216
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• 1999

Light curves of two near-contact binaries DO Cas and SW Lyn are analyzed to investigate their Roche configurations. We made new BVR observations for DO Cas and employed the published observation data for SW Lyn. Our four night observations for DO Cas were secured over 8 days so that the contamination by the intrinsic light variation is minimized. Based on the WD model, we found that DO Cas could be classified as a near-contact binary, while SW Lyn is better described by semi-detached configuration. Furthermore it is also possible to classify DO Cas as a contact binary. It appears that there are ambiguities in the class of near-contact configuration, and further observations and re-analysis are required to establish the near-contact nature of binary systems.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.461-465
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• 2010

We investigated the role of L-type $Ca^{2+}$ channel in receptor activator of nuclear factor-kappaB ligand (RANKL)-induced osteoclast formation. BayK 8644, a L-type $Ca^{2+}$ channel agonist, was shown to increase the RANKLinduced osteoclastogenesis and actin ring formation in mouse bone marrow-dereived macrophage (BMM) culture system. BayK 8644 stimulated RANKL-induced extracellular signal-regulated kinase (ERK) and p38 MAP kinase (MAPK) activation, which leads to increased nuclear factor of activated T cells (NFAT)c1 expression. Taken together, these data indicate that L-type $Ca^{2+}$ channel regulates osteoclast formation possibly through ERK- and p38-mediated NFATc1 expression.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.555-558
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• 2000

Layered perovskite La$_{2-x}$Ca$_{l-x}$Mn$_2$O$_{7}$ phases were synthesized by solid state reaction. Single phase R-P could be obtained in the range of 0.4$_{2-x}$Ca$_{l-x}$Mn$_2$O$_{7}$. About 30% of MR ratio was obtained at 270K when 5 T of magnetic field was applied.ied.ied.ied.

• Annual Conference of KIPS
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• 2009.04a
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• pp.881-884
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• 2009

유비쿼터스 환경에 관한 연구가 진행되고 있는 가운데 각 서비스의 접근 제어 역시 중요한 문제로 대두되었다. 이러한 관리 문제의 해결책 중 하나로 상황인지 역할기반 접근제어(Context-Aware Role-Based Access Control, CA-RBAC)가 제안되어 현재 많은 연구가 진행되고 있다. 지금까지의 연구를 보면 CA-RBAC는 단일 사용자의 시간, 위치 등 물리적 상황만을 역할 부여의 조건으로 활용하는데 그치고 있다. 본 논문에서는 기존의 CA-RBAC에 권한 충돌 조정 기능을 적용한 CA-RBAC을 보인다. 권한 충돌 조정 기능은 동일한 물리적 환경에서 서로 다른 권한을 가지는 사용자들이 함께 행동하여 접근 불가능한 대상에 접근이 가능해지는 문제를 조정한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.383-387
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• 1998

The vacuum-Bridgman equipment for large size diameter (4 inch more over) crystal growth was organized simply and the $CaF_2$ single crystal which was grown in the conditions of growth rate of 2mm/hr, freezing temperature gradient of $12^{\circ}C$/cm, have analyzed to keep excellent properties. Using Mo thermal reflector of umbrella shape, it could be eliminated the formation of polycrystalline. The preferential growth direction was (111) and the calculated lattice parameter was $5.460 \AA$ by XRD peaks. The secondary phases, also, was not formed by means of powder-XRD analysis. The value of EPD is $1.4{\times}10^4 \textrm{cm}^{-2}$ and the optical quality, which is the transmittance is 91% up in UV region, is suitable for optical components of UV applications.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.67.2-67.2
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• 2017

본 연구에서는 $SiO_2$ 미세구조 상에 Pd 나노입자(NPs)를 증착하여, 불소화된 마이크로-나노 계층구조를 갖는 Pd-decorated $SiO_2$($Pd/SiO_2$)를 제작하였다. 마이크로 크기의 거칠기를 갖는 $SiO_2$ 층은 졸-겔 공정을 사용해서 제조된 용액을 전기분사함으로써 제조되었다. 이어서, 자외선(UV)을 이용한 광 환원법을 이용해 Pd 나노입자를 $SiO_2$ 층에 형성했다. 생성된 표면은 마이크로-나노의 계층구조 형태를 보여주었다. 해당 시편의 불소화 처리 후, 마이크로-나노의 계층구조 표면은 $170^{\circ}$ 이상의 물 접촉각(water contact angle; WCA) 및 $5^{\circ}$ 이하의 슬라이딩 각(sliding angle)을 보여줌으로써 물에 대해 탁월한 소수성을 나타내었다. 또한, 커피($CA=161^{\circ}$), 우유($CA=162^{\circ}$), 쥬스($CA=163^{\circ}$), 그리고 글리세롤($CA=165^{\circ}$)에 대해서도 우수한 소수 특성을 보여주었다. 또한, 이들 $Pd/SiO_2$ 층은 우수한 장기내구성 및 자외선 저항성을 보여주었다. 그리고 이어진 기름에 대한 접촉각 측정을 통해 해당 시편이 소유 특성이 아닌 친유 특성을 보여준다는 것을 확인할 수 있었고, 기름에 대한 CA는 약 ${\sim}10^{\circ}$로 매우 우수한 친유 특성을 나타내었다. 이와 같은 결과는 자체세정이 가능한 표면 및 지능형 물/기름 분리 시스템과 같은 스마트 장치에서 초소수성-친유성 특성을 갖는 계층구조의 $Pd/SiO_2$ 층을 사용할 가능성을 명확하게 보여준다고 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.255-261
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• 2016

$CaCO_3$ was applied in various industries including rubber, plastics, paint, paper, food additives, and acid neutralizer, etc., owing to its excellent physical and chemical characteristics as well as various appearances of crystals and many reserves. In particular, research on controlling the structure and shape of $CaCO_3$ has attracted considerable attention recently, because the whiteness and physical characteristics of $CaCO_3$ depend on the size and shapes of the particles. In this study, $CaCO_3$ was synthesized using $CaCl_2$ and $(NH4)_2CO_3$, which has multi-shapes and structures, using a self-assembly method with a hydrothermal method. The structure and morphology of the $CaCO_3$ could be controlled by adjusting the pH and precursor concentration. In particular, the pH adjustment appeared to be a critical factor for the morphology and crystal form. In addition, the calcite and cubic shape were obtained at pH 7, while the mixed calcite, aragonite structure, and rod shapes appeared at pH 7 and over. Through an analysis of the particle formation process, the formation of the calcium carbonate particles was confirmed. The physicochemical properties of the synthesized $CaCO_3$ were analyzed by SEM, XRD, EDS, FTIR, and TG/DTA.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.441-445
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• 2005

태화강 주변지역 지하수의 계절적 수질 변화를 보고자 현장측정 항목(수온, pH, 알칼리도, 전기전도도), 일반 항목(증발잔류물, 총경도, 과망간산칼륨소비량), 음이온물질$(F^-,\;Cl^-,\;{NO_3}^-,\;{SO_4}^{2-})$, 양이온물질$(Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+)$등으로 구분하여 분석하였으며, 총 70개 지점을 대상으로 2004년 5월, 10월 2회에 걸쳐 실시하였다. 지역별 수질특성을 살펴보면 남구지역은 $Ca-Mg-HCO_3,\;Ca-Mg-HCO_3-Cl,\;Ca-Mg-Na-Cl-HCO_3,\;Na-Cl-HCO_3$의 4가지 유형이 전체 시료의 74%를 차지하였으며, $Ca-Mg-HCO_3$형이 가장 우세하게 나타났고, 중구지역 지하수에서는 $Ca-Mg-HCO_3-Cl,\;Ca-Mg-Na-HCO_3-Cl,\;Ca-Mg-HCO_3$의 3가지 유형이 전체 시료의 60%를 차지하는 것으로 나타났으며, 이중에서 $Ca-Mg-HCO_3-Cl$형이 가장 우세하게 나타났다. 두 지역의 수질 변화를 살펴보면. 전기전도도는 남구는 $731.5{\mu}s/m^3$에서 $529.8{\mu}s/m^3$, 중구는 $752.6{\mu}s/m^3$에서 $621.6{\mu}s/m^3$로 201.7, $131.0{\mu}s/m^3$만큼 작아져 두 지역 모두 같은 양상을 보였으나, Hardness 및 TDS의 경우 남구지역은 5월보다 10월에 평균, 최대값이 모두 낮게 나타났다. 또한 $Cl^-$의 경우 지역적, 계절적으로 큰 차이를 보이고 있으며 남구는 5월 68.2mg/l, 10월에는 61.7mg/l로 다소 감소하였으나 중구의 경우 5월 75.5mg/l, 10월 122.1mg/l로 다소 증가한 것으로 나타났다. 양이온 분포 비율 및 농도는 비슷하게 나타났으며, 계절적으로 5월보다 10월에 모두 높게 나타났다. 두 지역 모두 양이온물질 중 나트륨의 분포비율 및 농도가 5월보다 10월에 다소 높게 나타났다. 연구 지역 지하수의 계절적 수질변화를 살펴보면 두 지역간의 지하수질 및 분포특성에 있어 다소 차이를 보이고 있으며, 특히 중구 지역에서 5월보다 10월에 나트륨과 염소이온의 증가가 다소 나타나는 것으로 관찰되었다. 또한 연구지역 중 특이지점($Cl^-$:1,000mg/l이상)은 남구는 5월에 2개에서 10월에는 3개 지점으로 증가하였으며, 중구는 5월, 10월 모두 4개 지점으로 나타났다.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.37-44
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• 1995

A coprecipitation method was used for preparing Ca and Pt doped $SnO_{2}$-based material. Crystallite size and specific surface area were investigated by TEM, XRD and BET analysis. $SnO_{2}(Ca)/Pt$ based thick film devices were prepared by a screen printing technique for hydrocarbon gas detecting. Then the electrical and sensing characteristics of devices were investigated. As Ca and Pt addition, the crystal growth of $SnO_{2}$ was suppressed during calcining and sintering, and the sensitivity of $SnO_{2}(Ca)/Pt$ thick film to gas was enhanced. Also any difference in the sensing properties has to be attributed to the Pt and Au electrode. For the 2000 ppm $CH_{4}$, the sensitivity of $SnO_{2}(Ca)/Pt$ thick film devices were about 83% at an operating temperature of $400^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.618-628
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• 1998

Pure CaO, Mn-doped CaO, Mn/CaO, and K/CaO catalysts were prepared and tested as catalysts for the oxidative coupling of methane in the temperature range of 600 to 800$^{\circ}C$ to investigate the effects of Mn- and K-addition on the catalytic activity of calcium oxide. To characterize the catalysts, X-ray powder diffraction(XRD), XPS, SEM, DSC, and TG analyses were performed. The catalytic reaction was carried out in a single-pass flow reactor using on-line gas chromatography system. Normalized reaction conditions were generally $p(CH_4)/p(O_2)=250$ Torr/50 Torr, total feed flow rate=30 mL/min, and 1 atm of total pressure with He being used as diluent gas. Among the catalysts tested, 6.3 mol% Mn-doped CaO catalyst showed the best $C_2$ yield of 8.0% with a selectivity of 43.2% at 775$^{\circ}C$. The $C_2$ selectivity increased on lightly doped CaO catalysts, while decreased on heavily doped CaO([Mn] > 6.3 mol%) catalysts. 6 wt.% Mn/CaO and 6 wt.% K/CaO catalysts showed the $C_2$ selectivities of 13.2% and 30.9%, respectively, for the reaction. Electrical conductivities of CaO and Mn-doped CaO were measured in the temperature range of 500 to 1000$^{\circ}C$ at Po2's of $10^{-3}\; to\;10^{-1}\;atm.$ The electrical conductivity was decreased with Mn-doping and increased with increasing $P0_2$in the range of $10^{-3}\;to\;10^{-1}\;atm,$ indicating the specimens to be p-type semiconductors. It was suggested that the interstitial oxygen ions formed near the surface can activate methane and the formation of interstitial oxygen ions was discussed on the basis of solid-state chemistry.