• 한국진공학회지
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• 제19권4호
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• pp.314-318
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• 2010

다결정 실리콘 웨이퍼 표면에 대면적 reactive ion etching (RIE) 장비로 표면 텍스쳐를 형성한 뒤 태양전지를 제작하였다. 웨이퍼 표면에 텍스쳐를 형성하는 것은 광학적 손실을 줄이기 위해 일반적으로 사용되는 방법으로 alkaline etching이 사용된다. 그러나 다결정 실리콘 태양전지의 경우 재료의 결정 방향에 따라 식각되는 alkaline etching은 텍스쳐링의 모양을 제어할 수 없어 효과적이지 못하다. 이와 달리 플라즈마 식각방법을 사용하면 표면 텍스쳐의 모양을 효과적으로 제어하여 조금 더 낮은 반사율을 얻을 수 있다. 하지만 텍스쳐 모양 조절로 얻은 낮은 반사율이 항상 높은 변환효율을 얻을 수 있는 것은 아니다. 본 연구에서는 대면적 RIE 공정 조건별로 얻은 태양전지 표면 텍스쳐의 모양에 따라 각각의 반사율과 양자효율 및 변환효율이 미치는 영향을 살펴보았다.

• Korean Circulation Journal
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• 제54권4호
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• pp.172-186
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• 2024

Background and Objectives: Long-term pathological myocardial hypertrophy (MH) seriously affects the normal function of the heart. Dronedarone was reported to attenuate left ventricular hypertrophy of mice. However, the molecular regulatory mechanism of dronedarone in MH is unclear. Methods: Angiotensin II (Ang II) was used to induce cell hypertrophy of H9C2 cells. Transverse aortic constriction (TAC) surgery was performed to establish a rat model of MH. Cell size was evaluated using crystal violet staining and rhodamine phalloidin staining. Reverse transcription quantitative polymerase chain reaction and western blot were performed to detect the mRNA and protein expressions of genes. JASPAR and luciferase activity were conducted to predict and validate interaction between forkhead box O3 (FOXO3) and protein kinase inhibitor alpha (PKIA) promoter. Results: Ang II treatment induced cell hypertrophy and inhibited sirtuin 1 (SIRT1) expression, which were reversed by dronedarone. SIRT1 overexpression or PKIA overexpression enhanced dronedarone-mediated suppression of cell hypertrophy in Ang II-induced H9C2 cells. Mechanistically, SIRT1 elevated FOXO3 expression through SIRT1- mediated deacetylation of FOXO3 and FOXO3 upregulated PKIA expression through interacting with PKIA promoter. Moreover, SIRT1 silencing compromised dronedarone-mediated suppression of cell hypertrophy, while PKIA upregulation abolished the influences of SIRT1 silencing. More importantly, dronedarone improved TAC surgery-induced MH and impairment of cardiac function of rats via affecting SIRT1/FOXO3/PKIA axis. Conclusions: Dronedarone alleviated MH through mediating SIRT1/FOXO3/PKIA axis, which provide more evidences for dronedarone against MH.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.8.1-8.1
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• 2011

Nanocrystalline titanium dioxide ($TiO_2$) materials have been widely used as an electron collector in DSSC. This is required to have an extremely high porosity and surface area such that the dye can be sufficiently adsorbed and be electronically interconnected, resulting in the generation of a high photocurrent within cells. In particular, their geometrical structures and crystalline phase have been extensively investigated as important issues in improving its photovoltaic efficiency. In this study, we present a new strategy to fabricate a photoelectrode having a periodic structured $TiO_2$ film templated from 1D or 3D polystyrene (PS) microspheres array. Monodisperse PS spheres of various radiuses were used for colloidal array on FTO glasses and two types of photoelectrode structures with different $TiO_2$ materials were investigated respectively. One is the igloo-shaped electrode prepared by $TiO_2$ deposition by RF-sputtering onto 2D microsphere-templated substrates. At the interface between the film and substrate, there are voids formed by the decomposition of PS microspheres during the calcination step. These holes might be expected to play the predominant roles as scattering spherical voids to promote a light harvesting effect, a spacious structure for electrolytes with higher viscosity and effective paths for electron transfer. Additionally the nanocrystalline $TiO_2$ phase prepared by the RF-sputtering method was previously reported to improve the electron drift mobility within $TiO_2$ electrodes. This yields solar cells with a cell efficiency of 2.45% or more at AM 1.5 illumination, which is a very remarkable result, considering its $TiO_2$ electrode thickness (<2 ${\mu}m$). This study can be expanded to obtain higher cell efficiency by higher dye loading through the increase of surface area or multi-layered stacking. The other is the inverse opal photonic crystal electrode prepared by titania particles infusion within 3D colloidal arrays. To obtain the enlargement of ordered area and high quality of crystallinity, the synthesis of titania particles coated with a organic thin layer were applied instead of sol-gel process using the $TiO_2$ precursors. They were dispersed so well in most solvents without aggregates and infused successfully within colloidal array structures. This ordered mesoporous structure provides the large surface area leading to the enough adsorption of dye molecules and have an light harvesting effect due to the photonic band gap properties (back-and-forth reflection effects within structures). A major advantage of this colloidal array template method is that the pore size and its distribution within $TiO_2$ photoelectrodes are determined by those of latex beads, which can be controlled easily. These materials may have promising potentials for future applications of membrane, sensor and so on as well as solar cells.

• Journal of the Korean Wood Science and Technology
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• 제34권4호
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• pp.1-8
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• 2006

제조 온도에 따른 목탄의 해부학적 특성을 주사전자현미경법으로 조사하였다. 목탄은 실험실용 전기로를 이용하여 $400^{\circ}C$, $600^{\circ}C$, $800^{\circ}C$, $1000^{\circ}C$의 각 온도 조건에서 굴참나무재를 10분간 탄화시켜 제조하였다. 관찰 결과 목탄의 구조는 제조 온도에 따라 큰 차이를 보였다. $400^{\circ}C$에서 제조한 목탄의 횡단면은 깨끗하게 나타났으나 온도 증가에 따라 거칠고 할렬이 많은 단면을 나타냈다. 세포벽은 벽층 구조가 소실되고 유리와 같이 매끄럽고 균질한 구조를 보여주었다. $400^{\circ}C$에서 제조한 목탄은 유세포 상호간에 간극이 거의 없었으나 $600^{\circ}C$ 이상에서는 유세포 간에 분리가 발생하여 간극이 관찰되었다. 방사유세포와 축방향유세포의 표면에는 직경 $2{\sim}4{\mu}m$의 사마귀 모양의 돌기물이 다수 관찰되었고, $600^{\circ}C$ 이상에서 광방사조직에 커다란 할열할렬이 자주 발생하였다. 결정 세포 중에 존재하는 결정의 표면은 제조 온도에 따라 다르게 나타났다. 즉, $400^{\circ}C$와 $600^{\circ}C$에서 제탄한 목탄 중의 결정은 매끄러운 표면을 나타내고 있으나 $800^{\circ}C$ 이상에서 제조한 목탄의 것은 표면이 거칠고 작은 구멍이 나타나 스폰지와 같은 외형을 보여주었다.

• Applied Microscopy
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• 제41권1호
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• pp.61-67
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• 2011

헴프종자는 보통 길이 2~6 mm, 직경 2~4mm의 크기를 갖는 무배유종자로서 두껍고 단단한 외종피와 얇은 녹색의 내종피에 의해 둘러싸여 있었다. 외종피의 외부는 과피가 이를 전체적으로 둘러싸고 있었으며 과피의 표면은 부분적으로 목화된 각두가 덮고 있었다. 파편상의 각두는 과경의 부착흔적인 함몰된 기부쪽에서 합쳐있었다. 종피의 내부에는 2장의 자엽과 하배축-유근 주축으로 구성된 U자형의 구부러진 배가 발달하였다. 배의 표피조직은 크기가 다른 장방형 세포들로 구성되어 있었으며 자엽을 이루는 세포는 $1.8{\sim}5.0{\mu}m$의 단백질과립과 $0.8{\sim}3.0{\mu}m$의 지질과립이 분포하였다. 단백질과립의 중심부에는 전자밀도가 높은 globoid crystal 구조가 형성되어 있었고, 내부는 격자구조를 이루고 있었다. 한편, 단백질과립의 가장자리는 전자밀도가 낮은 이질적인 matrix로 구성되어 있었다. Globoid의 단백질과립은 이후 주변부로부터 분해되는 양상이 나타났다. 단백질과립이 분해가 일어난 뒤 지질과립은 불규칙한 형태로 분해, 소실되었다. 이들은 이후 단백질 과립과 융합되어 큰 액포를 형성하였다.

• 대한치과보철학회지
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• 제44권3호
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• pp.343-355
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• 2006

Statement of problem. The success of osseointegration can be enhanced with an implant that has improved surface characteristics. Anodic oxidation is one of the surface modifying method to achieve osseointegration. Voltage of anodic oxidation can change surface characteristics and cell activity Purpose. This study was performed to evaluate MG63 cell responses such as affinity, proliferation and to compare surface characteristics of anodic oxidized titanium in various voltage. Material and method. The disks for cell culture were fabricated from grade 3 commercially pure titanium,1 m in thickness and 12 mm in diameter. Surfaces of 4 different roughness were prepared. Group 1 had a machined surface, used as control. Group 2 was anodized under 220 V, group 3 was anodized under 300 V and group 4 was anodized under 320 V. The microtopography of specimens was observed by scanning electron microscope (JSM-840A, JEOL, Japan) and atomic force microscope(Autoprobe CP, Park Scientific Instrument, USA). The surface roughness was measured by confocal laser scanning microscope(Pascal, LSM5, Zeiss, Germany). The crystal structure of the titanium surface was analyzed with x-ray diffractometer(D8 advanced, Broker, Germany). MG63 osteoblast-like cells were cultured on these specimens. The cell morpholgy was observed by field emission electron microscope(Hitachi S-4700, Japan). The cell metabolic and proliferative activity was evaluated by MTT assay Results and conclusion. With in limitations of this in vitro study, the following conclusions were drawn. 1. In anodizing titanium surface, we could see pores which did not show in control group. In higher anodizing voltage, pore size was increased. 2. In anodizing titanium surface, we could see anatase. In higher anodizing voltage, thicker oxide layer increased crystallinity(anatase, anatase and rutile mixed). 3. MG63 cells showed more irregular, polarized and polygonal shape and developed more lamellipodi in anodizing group as voltage increased. 4. The activity of cells in MTT assay increased significantly in group 3 and 4 in comparison with group 1 and 2. However, there was no difference between group 3 and 4 at P<0.05. Proliferation of MG63 cells increased significantly in pore size($3-5.5{\mu}m$) of group 3 and 4 in comparison with in pore size($0.2-1{\mu}m$ ) of group 2.

• Applied Microscopy
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• 제9권1호
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• pp.57-69
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• 1979

과피가 녹색이고 배의 길이가 $250{\mu}$인 미성숙 과정을 거쳐 발아시까지 배 및 배유세포의 미세구조 변화를 관찰한 결과를 요약하면 다음과 같다. 1. 배의 길이가 $250{\mu}$인 미성숙 종자의 배세포는 세포질이 비교적 충실하나 mitochondria의 Cristae 및 plastid는 미분화상태이고 가끔 dictyosome이 관찰되었다. 액포안에는 전자밀도가 높은 globoid 를 함유하는 것도 있었다. 소포체는 대부분 한면소포체이고 외형질에는 spherosome을 많이 함유하고 있었다. 배유세포는 spherosome과 이들로 둘러싸인 전자밀도가 높고 균질성인 protein body로 충만되었고 이들로 인하여 세포기관은 관찰되지 않았다. 2. 과피가 홍색인 종자의 배세포는 cristae가 발달한 mitochondria가 관찰되었으며, 전자밀도가 높은 globoid가 증가하였고 액포는 확장되었다. 배유세포에는 spherosome이 증가하고 있었으며 protein body는 확장되어. 그 내부에는 전자밀도가 높은 globoidal crystal이 분산되어 있었다. 3. 종피가 열개한 종자의 배축의 전형성층과 유아세포에서는 Golgi vacuole과 vesicle이 발달되었으며 mitochondria의 cristae는 매우 분화되었다. spherosome은 매우 많이 나타났고 유근세포, 배축의 주변세포 및 자엽세포의 액포는 매우 분화되었다. 배유세포는 spherosome으로 충만되어 있고 그 내질에는 전자밀도가 높고 작은 입자를 지니고 있었다. Protein body는 단일막으로 둘러싸여 있음이 확인되었다. 세포질내에는 구형체와 spherosome 주변의 세포질에 acid phosphatase의 활성을 나타냈다. 4. 파종시 자엽의 외면부 세포는 spherosome이 급격히 증가하였고 protein body도 관찰되었다. 세포기관들은 분화되어 있었고 전분을 함유하는 색소체가 출현하였다. 5. 파종시킨 후 발아할 때까지 자엽의 외측 $2{\sim}3$열세포, 배축의 주변세포, 유근부 세포에서는 spherosome이 증가하였고 전분립을 함유하는 plastid 도 증가하였다. 배를 구성하는 세포의 내형질의 액포부근에는 mitochondria와 microbody 가 혼재하고 있음이 관찰되었다. 발아시기가 가까워 질수록 배와 연접하는 배유세포에는 액포가 매우 분화되고 spherosome은 감소되는 반면 액포내에는 무정형의 전자밀도가 높은 물질이 증가하였다. 그밖의 배유세포에는 spherosome이 감소됨에 따라 mitochondria는 증가되고 전자밀도가 높은 소구체가 형성되어 증가되었다. Protein body의 외질은 감소되고 전자밀도가 낮은 부위는 확장되며 이는 서로 융합하여 외연부는 없어지고 기질속에 소입자들이 형성되었다. 6. 발아기의 배유세포안에는 spherosome이 감소되고, protein body는 서로 융합되어 한 세포내에 $2{\sim}3$개로 충만되어 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2148-2153
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• 2007

The electricity conversion-efficiency of solar cell for commercial application is about 6-15%. More than 85% of the incoming solar energy is either reflected or absorbed as heat energy. Consequently, the working temperature of the photovoltaic cells increases considerably after prolonged operations and the cell's efficiency drops significantly. PV/T refers to the integration of a PV module and a solar thermal collector in a single piece of equipment. By cooling the PV module with a fluid steam like air or water, the electricity yield can be improved. At the same time, the heat pick-up by the fluid can be to support space heating or service hot-water systems. In this study, a pulsating heat pipe solar heat collector was combined with single-crystal silicon photovoltaic cell in hybrid energy-generating unit that simultaneously produced low temperature heat and heat and electricity. This experiment was investigating thermal and electrical efficiency for evaluation of a PV/T system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.185-185
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• 2009

The aligned liquid crystals (LCs) display on SiNx thin films using ion-beam (IB) irradiation was studied with controllability ofpretilt angle depending on incident energies of the IB. Plasma-enhanced chemical vapor deposition (PECVD) was used to orient the LCs on SiNx alignment films. The LCs alignment property for the SiNx thin films were observed to verify the practical application potential (figure1). A good LCs alignment of vertical alignment LCs cells on SiNx thin film surfaces irradiated with incident IB energy of 1800eV was achieved. Also, a good LC alignment by the IB irradiation on the SiNx thin film surface was observed at an annealing temperature of $180^{\circ}C$. However, the alignment defects of the nematic liquid crystal was observed at an annealing temperature above $230^{\circ}C$. The atomic force microscopy (AFM) images of LCs on SiNx thin film surfaces irradiated with IB energy was used for the surface analysis.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1499-1504
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• 2008

Pyrazine derivatives bind to b-RAF receptor which is important in cancer therapy. The ligand-receptor interactions have been studied by comparative molecular field analysis (CoMFA) and molecular docking methods. Applying conventional ligand-based alignment schemes for the whole set was not successful. However, QM and DFT results suggested that some ligands have electrostatic interaction while others have steric interactions. On the basis of these results, we divided the dataset into two subsets. Electrostatic effect was found to be important in one set while steric effect for the other. Best docking modes were obtained for each subset based on the available crystal structure. These receptor-guided CoMFA models propose an interesting possibility which is difficult to obtain otherwise. i.e., in one binding mode the electrostatic interaction plays a key role for one subset ($q^2$ = 0.46, $r^2$ = 0.98), while in another binding mode steric effect is important with another subset ($q^2$ = 0.43, $r^2$ = 0.74).