• 대한기계학회논문집A
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• 제32권9호
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• pp.754-760
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• 2008

A two-photon induced photoreduction process suggests a possibility for fabricating complicated metallic microstructures which can be applied to 3-D micro-circuits and optical devices, etc. The process employs the photoreduction of silver ions in a metallic solution which is composed of metallic salt ($AgNO_3$) and watersoluble polymer ((poly(4-styrenesulfonique acid) 18wt. % in $H_2O$, $(C_8H_8O_3S)_n$)). In this process, the improvement of the resolution and the uniformity of fabricated metallic structures are important issues. To address these problems, continuous forming window (CFW) is obtained from a parametric study on the conditions of laser power and scanning velocity and the direct seed generation (DSG) method is proposed. Silver nano particles are uniformly generated in a metallic solution through the DSG method, which enables the decrease of a laser power to trigger the photoreduction of silver ions as well as the increase of metal contents in a metallic solution. So the two-photon induced photoreduction property of a metallic solution is improved. Through this work, precise silver patterns are fabricated with a minimum line width of 400 nm.

• 한국광학회지
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• 제21권2호
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• pp.61-68
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• 2010

최근 LED TV로 각광받고 있는 대형 LCD TV용 LED(Light Emitting Diode, 고체발광다이오드) 백라이트에 사용되는 도광판의 광구조를 최적화하여 LED에 의해 발생하는 휘점을 제거하고 조도균일도를 향상시키기 위한 시뮬레이션 연구를 진행하였다. 시뮬레이션 모델로 설정된 엣지형 백라이트는 LCD TV용으로 사용될 수 있는 두께 3 mm의 도광판, 측면에 배치된 세 개의 백색 LED와 램프 커버, 도광판의 하면에 배치된 반사 필름으로 구성되어 있다. 일반적인 엣지형 백라이트용 도광판과 같이 도광판의 입광면에 패턴이 형성되어 있지 않은 경우에는 도광판 상면의 조도균일도가 입광면과 LED 사이의 거리에 민감하게 의존하였다. 입광면과 LED 사이의 거리가 커질수록 조도균일도는 개선되다가 일정 거리 이상이 되면 개선이 둔화되는 경향성을 보였다. 반면에 도광판의 입광면에 렌티큘라(lenticular) 렌즈 배열이나 톱니모양(Serration)과 같은 미세 굴절 패턴을 형성하는 경우 LED가 입광면에 거의 붙어 있는 경우에도 패턴이 없는 경우에 비해 우수한 조도균일도를 보인다는 것을 알 수 있었고 조도균일도가 LED와 입광면 사이의 거리에 의존하는 정도가 줄어든다는 점도 확인하였다. 동일조건에서는 톱니모양 패턴이 렌티큘라 렌즈에 비해 우수한 조도균일도를 나타내었고 굴절률의 변화를 통해 추가적인 균일도 개선 효과를 얻을 수 있음도 확인하였다. 따라서 도광판의 입광면에 굴절 기능을 가지는 미세 패턴을 형성하고 그 광구조를 최적화하는 것은 LED에 의한 휘점 형성을 억제하고 LCD 측면의 비발광영역(베젤)을 줄이는데 있어서 매우 효과적인 방법이 될 수 있다는 것을 확인하였다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.227-235
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• 2000

Agricultural products are easily deformable its shape because of some external forces. However, these force behavior is difficult to measure quantitatively. Until now, many researches on the mechanical property was performed with various methods such as material testing, chemical analysis and non-destructive methods. In order to investigate force behavior on the cellular unit of agricultural products, electro-microscope based 3D image processing method will contribute to analysis of plant cells behavior. Before image measurement of plant cells, plant sample was cut off cross-sectioned area in a size of almost 300-400 ${\mu}$ m units using the micron thickness device, and some of preprocessing procedure was performed with fixing and dyeing. However, the wall structure of plant cell is closely neighbor each other, it is necessary to separate its boundary pixel. Therefore, image merging and shrinking algorithm was adopted to avoid disconnection. After then, boundary pixel was traced through thinning algorithm. Each image from the electro-microscope has a information of x,y position and its height along the z axis cross sectioned image plane. 3D image was constructed using the continuous image combination. Major feature was acquired from a fault image and measured area, thickness of cell wall, shape and unit cell volume. The shape of plant cell was consist of multiple facet shape. Through this measured information, it is possible to construct for structure shape of unit plant cell. This micro unit image processing techniques will contribute to the filed of agricultural mechanical property and will use to construct unit cell model of each agricultural products and information of boundary will use for finite element analysis on unit cell image.

• 대한화학회지
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• 제39권9호
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• pp.685-691
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• 1995

결정 분자 궤도함수[EHTB]를 계산할 수 있는 VAX 컴퓨터용 EHMACC와 EHPC 프로그램을, 마이크로-소프트 포트란을 이용하는 PC로 계산할 수 있도록 변환하였다. 이 프로그램을 이용하여 perovskit 구조의 $LaNiO_3$ 단위세포와 ($2{\times}2{\times}1$)으로 확장된 구조에 대한 띠 구조를 계산한 결과, ${\Gamma}{\rightarrow}H,\;H{\rightarrow}N$ 및 $N{\rightarrow}{\Gamma}$ 방향(2차원)에서는 bend gap이 0.35eV인 반도체의 성질을 나타내고, ${\Gamma}{\rightarrow}P$와 $P{\rightarrow}N$ 방향(3차원)에서는 금속성의 성질을 나타내었다. 또 이들 결정에 관한 DOS와 COOP를 고찰한바, $LaNiO_3$에서 산소원자의 DOS는 니켈원자의 결함보다는 산소원자의 위치에 영향을 받아 서로 다른 종류의 산소원자로 존재할수 있음을 알았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.6-8
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• 2004

Recently, the PM type stepping motor preferred solution for many small electronics position determination devices since it is small in size. Thus, there are glowing demands for permanent magnet(PM) type stepping motor that greater mechanical output, smaller size. This paper deals with a study of the miniaturization of the PM type stepping motor with claw-poles. We introduced the small-sized PM type stopping motor that has new structure and analyzed the magnetic characteristic of it versus general type model using 3-D finite element analysis(FEA).

• Genomics & Informatics
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• 제19권3호
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• pp.29.1-29.10
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• 2021

In our previous studies, we have demonstrated the association of certain variants of the thyroid-stimulating hormone receptor (TSHR), thyroid peroxidase (TPO), and thyroglobulin (TG) genes with congenital hypothyroidism. Herein, we explored the mechanistic basis for this association using different in silico tools. The mRNA 3'-untranslated region (3'-UTR) plays key roles in gene expression at the post-transcriptional level. In TSHR variants (rs2268477, rs7144481, and rs17630128), the binding affinity of microRNAs (miRs) (hsa-miR-154-5p, hsa-miR-376a-2-5p, hsa-miR-3935, hsa-miR-4280, and hsa-miR-6858-3p) to the 3'-UTR is disrupted, affecting post-transcriptional gene regulation. TPO and TG are the two key proteins necessary for the biosynthesis of thyroid hormones in the presence of iodide and H₂O₂. Reduced stability of these proteins leads to aberrant biosynthesis of thyroid hormones. Compared to the wild-type TPO protein, the p.S398T variant was found to exhibit less stability and significant rearrangements of intra-atomic bonds affecting the stoichiometry and substrate binding (binding energies, ΔG of wild-type vs. mutant: -15 vs. -13.8 kcal/mol; and dissociation constant, K_d of wild-type vs. mutant: 7.2E^-12 vs. 7.0E^-11 M). The missense mutations p.G653D and p.R1999W on the TG protein showed altered ΔG(0.24 kcal/mol and 0.79 kcal/mol, respectively). In conclusion, an in silico analysis of TSHR genetic variants in the 3'-UTR showed that they alter the binding affinities of different miRs. The TPO protein structure and mutant protein complex (p.S398T) are less stable, with potentially deleterious effects. A structural and energy analysis showed that TG mutations (p.G653D and p.R1999W) reduce the stability of the TG protein and affect its structure-functional relationship.

• 한국결정성장학회지
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• 제11권4호
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• pp.170-175
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• 2001

It was possible to grow the $Al_{2}O_{3}$ based $Y_{3}A_{5}O_{12}(YAG),ZrO_{2}$ binary and ternary eutectic fibers using micro-pulling down method with a growing rate of 0.1~15 mm/min. While $Al_{2}O_{3}/ZrO_{2}$ showed cellular-lamellar structure, $Al_{2}O_{3}$/YAG and $Al_{2}O_{3}$/YAG/$ZrO_{2}$ternary eutectic fibers showed homogeneous Chinese script lamellar structures. The microstructures of $Al_{2}O_{3}/ZrO_{2}$ binary eutectic fibers changed with solidification rate from lamellar pattern to cellular structure. The interlamellar spacing agreed with the inverse-square-root dependance on pulling rate according to $\lambda$=$kv_p\;{-1/2}$. $Al_{2}O_{3}/ZrO_{2}$ binary eutectic fibers recorded the highest tensile strength of about 1560MPa at room temperature. $Al_2O_3/YAG/ZrO_2$ternary eutectic fiber showed excellent thermal stability to $1200^{\circ}C$ without significant decrease. The maximum strength of ternary eutectic fibers recorded were 1100MPa at $25^{\circ}C$ and 970MPa at $1200^{\circ}C$, respectively.

• 한국주조공학회지
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• 제40권3호
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• pp.61-65
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• 2020

Rheo-diecasting with stirring has been used in many material industries. As the 4th Industrial Revolution approaches the world, eco-friendly high-strength and light-weight materials become more important. Casting methods have been studied and used for aluminum-alloy automobile parts. This study carried out the effect analysis of the micro-structure and mechanical properties, such as yield/ultimate tensile strength, elongation, and hardness, of A356 using the 6-pole EMS (electro-magnetic stirring) casting process with a high electromagnetic force. As a result, the hardness and elongation of the A356 after T6 heat-treatment show a significant improvement, respectively, by 20% and 50%.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2001년도 춘계학술대회논문집:21세기 신지식정보의 창출
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• pp.224-231
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• 2001

2.45 GHz 마이크로웨이브를 사용하는 전자회전공명 플라즈마를 이용하여 화학적 기상증착(electron cyclotron resonance plasma enhanced chemical vapor deposition; ECR-PECVD) 방법으로 ECR 마이크로웨이브 power, CH$_4$/H$_2$가스 혼합비와 유량, 증착시간, 그리고 기판 bias 전압 등을 변화시켜 가면서 수소가 함유된 비정질 탄소(a-C:H) 박막을 증착하였고, 증착시킨 박막의 특성을 AES(Auger electron spectroscopy), ERDA(elastic recoil detection analysis), FTIR(Fourier transform infrared) 및 Raman 측정 등으로 조사하였다. 증착시킨 a-C:H 박막은 탄소 및 수소원소들로만 구성되어 있음을 AES 측정으로 확인하였다. 그리고 FTIR 측정으로부터 a-C:H 박막은 대부분 sp$^3$결합을 하고 있고 일부는 sp$^2$결합을 하고 있음을 확인하였으며, CH$_4$/H$_2$가스 혼합비와 유량의 변화가 a-C:H 박막의 탄소와 수소의 결합구조에 큰 영향을 미치지 않았으며, 다만 증착시간이 증가할수록 탄소와 수소 원자들의 결합구조가 $CH_3$구조에서 CH$_2$나 CH 구조로 변하고 있음을 알았다. 또한 Raman 스펙트럼의 Gaussian curve fitting을 통하여 sp$^3$/sp$^2$의 결합수에 비례하는 D 및 G peak의 면적 강도비(I$_{D}$/l$_{G}$)는 기판 bias 전압을 증가시킬수록 증가하였으며, 경도도 역시 증가하였다.하였다.

• 한국축산식품학회지
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• 제43권4호
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• pp.712-720
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• 2023

Osteoporosis is a growing global health concern primarily associated with decreased estrogen in postmenopausal women. Recently, some strains of probiotics were examined for potential anti-osteoporotic effects. This study intended to evaluate the impacts of Lactiplantibacillus plantarum MGE 3038 strain (MGE 3038) in ovariectomized rats. For this purpose, twelve weeks old female Wistar rats (n=21; 250-300 g) were divided into 3 groups; ovariectomy (OVX) group, OVX/MGE 3038 group and Sham group (control). In these groups; two went through respective OVX and one had daily MGE 3038 administration through oral gavage. Prior to 16 weeks after OVX, we collected blood samples and extracted the tibiae. We scanned the extracted tibiae by in-vivo micro-computed tomography (micro-CT) and evaluated pathology by hematoxylin and eosin (H&E) and Masson's trichrome staining. The serum levels of C-telopeptide of type I collagen (CTX), osteocalcin (OC), and the receptor activator of nuclear factor-κB ligand (RANKL) were examined. The OVX/MGE 3038 group showed increases in bone mineral density, trabecular bone volume, trabecular number, and trabecular thickness (Tb.Th), and a decrease in trabecular spacing than the OVX group. However, OVX/MGE 3038 group and control group were measurably comparable in Tb.Th. Micro-CT, H&E, and Masson's trichrome findings exhibited increased preservation and maintenance of trabecular bone structure in the OVX/MGE 3038 group in comparison to the OVX group. In serum, the levels of CTX, OC and RANKL were significantly different between the OVX and OVX/MGE 3038 groups. Taken together, L. plantarum MGE 3038 could be helpful for the treatment of osteoporosis.