• 제목/요약/키워드: 3D micro-structure

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MIRIS 우주관측카메라의 기계부 개발 (DEVELOPMENT OF THE MECHANICAL STRUCTURE OF THE MIRIS SOC)

  • 문봉곤;정웅섭;차상목;이창희;박성준;이대희;육인수;박영식;박장현;남욱원;;;양순철;이선희;이승우;한원용
    • 천문학논총
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    • 제24권1호
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    • pp.53-64
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    • 2009
  • MIRIS is the main payload of the STSAT-3 (Science and Technology Satellite 3) and the first infrared space telescope for astronomical observation in Korea. MIRIS space observation camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}\times3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200 K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI (Multi Layer Insulation) of 30 layers, and GFRP (Glass Fiber Reinforced Plastic) pipe support in the system. Optomechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

유체-구조물 상호작용을 고려한 댐 구조체와 수압철관의 내진성능평가 (Seismic Performance Evaluation of Dam Structures and Penstock Considering Fluid-Structure Interaction)

  • 허소현;남광식;정영석;권민호
    • 토지주택연구
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    • 제13권1호
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    • pp.141-150
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    • 2022
  • 국내 대규모 지진 이후 구조물의 내진에 대한 연구 필요성이 커짐에 따라 행정안전부에서는 기존의 내진설계기준 공통적용사항을 개정하여 국가내진성능 목표치를 상향하였으며 새로 개정된 내진설계기준의 성능목표치에 대한 연구가 필요하게 되었다. 이에 본 논문에서는 실제 노후화된 Test-Bed의 댐 제체와 내부에 매립되어 있는 수압철관과 유체를 여러 변수를 도입하여 3차원 유한요소법으로 모델링 하였으며 수압철관 내부 유체의 동수압으로 인한 거동을 분석하고 개정된 현행 내진설계 기준법에 부합하는 지진파에 대한 댐 제체와 수압철관의 안전성을 확인하였다. 3차원 유한요소해석결과 수압철관의 수충격에 의한 응력변화가 매우 작았으며 이를 통해 지진상황에서 수충격 보다 동수압의 영향이 더 큰 것을 확인할 수 있었다. 동수압이 SPH 형태인 경우 지진동으로 인한 유체의 거동과 응력 발생 위치를 유효하게 나타낼 수 있으며 취약부 분석에 더욱 용이할 것으로 분석되었다. 부식을 고려한 해석결과 수압철관이 제체의 매립되어 있기 때문에 응력 분산의 정도가 작아져 강재 항복응력의 1% 이하로 매우 작은 응력결과를 보였다. 또한 콘크리트 댐 제체의 상류 유입부의 미소 인장균열 발생 가능성이 있으나 수압철관의 응력증가에 큰 영향을 끼치지 않는 것으로 나타났으며 개정된 유효지반가속도의 지진상황에서 안전한 것으로 판단된다.

Mechanical and Chemical Characterization of NbNx Coatings Deposited by ICP Assisted DC Magnetron Sputtering

  • Jun, Shinhee;Kim, Junho;Kim, Sunkwang;You, Yong Zoo;Cha, Byungchul
    • 열처리공학회지
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    • 제27권1호
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    • pp.10-14
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    • 2014
  • Niobium nitride coatings have many potential thin film applications due to their chemical inertness, good mechanical properties, temperature stability and superconducting properties. In this study, $NbN_x$ coatings were prepared by inductively coupled plasma (ICP) assisted DC magnetron sputtering method on the surface of AISI 304 austenitic stainless steels. Effects of target power were studied on mechanical and chemical properties of the coatings. The coating structure was analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The coating hardness was measured by micro-knoop hardness tester. The coating thickness was measured using a 3D profiler and wear characteristics were estimated using a ball-on-disk wear tester. The thickness of the $NbN_x$ coatings increased linearly from 300 nm to 2000 nm as the Nb target power increased, and it showed over $HK_{0.005}$ 4000 hardness above Nb target power of 300 W. Hexagonal ${\delta}^{\prime}$-NbN phase and cubic ${\delta}$-NbN phase were observed in the coating films and the hardness of the NbNx coatings was higher when these two peaks were mixed. The corrosion resistance increased with the increase of the Nb target power.

탈세포화 기법을 이용한 돼지 바이오 스캐폴드: 환자 맞춤형 장기재생을 위한 역분화 줄기세포 동물모델 (Decellularized Bioscaffold of Pig Organs: A Tool for Patient-specific Organogenesis Using Induced Pluripotent Stem Cells)

  • 박경미;곽호현;남현숙;박인철;전용환;박성민;이승태;우제석;우흥명
    • 한국임상수의학회지
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    • 제28권1호
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    • pp.57-62
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    • 2011
  • The shortage of transplantable kidneys has many efforts to regenerate bioartificial kidneys using transgenic animals and diverse kinds of scaffolds which are important tools for cell seeding. However, there are many limitations for clinical applications so far. Recently, decellularized bioscaffolds using animal organs come into spotlight because of its many superior advantages. In current study, we produced decellularized kidney bioscaffolds of pig which is an attractive animal as a clinical model for human. We decellularized pig kidneys with 1% SDS detergent solution using peristaltic pump systems for 12h. After decellularization process, the kidney bioscaffolds preserved intact 3D morphology including glomerular structure and almost DNA from pig was entirely removed. In addition, this process could preserve micro vascular network which is necessary for cell survival. Although, additional studies for recellularization and transplantation should be required, the decellular vascularized kidney bioscaffolds might have many potentials for kidney regeneration.

마이크로 머시닝 기술을 이용한 니켈기반의 압전 진동형 에너지 하베스터 제작 (Fabrication of Nickel-based Piezoelectric Energy Harvester from Ambient Vibration with Micromachining Technology)

  • 차두열;이재혁;장성필
    • 한국전기전자재료학회논문지
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    • 제25권1호
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    • pp.62-67
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    • 2012
  • Owing to the rapid growth of mobile and electronic equipment miniaturization technology, the supply of micro mobile computing machine has been fast raised. Accordingly they have performed many researches on energy harvesting technology to provide promising power supply equipment to substitute existing batteries. In this paper, in order to have low resonance frequency for piezoelectric energy harvester, we have tried to make it larger than before by adopting nickel that has much higher density than silicon. We have applied it for our energy harvesting actuator instead of the existing silicon based actuator. Through such new concept and approach, we have designed energy harvesting device and made it personally by making with micromachining process. The energy harvester structure has a cantilever type and has a dimension of $10{\times}2.5{\times}0.1\;mm^3$ for length, width and thickness respectively. Its electrode type is formed by using Au/Ti of interdigitate d33 mode. The pattern size and gap size is 50 ${\mu}m$. Based on the measurement of the nickel-based piezoelectric energy harvester, it is found to have 778 Hz for a resonant frequency with no proof mass. In that resonance frequency we could get a maximum output power of 76 ${\mu}W$ at 4.8 $M{\Omega}$ being applied with 1 g acceleration.

Characteristics of NbN Films Deposited on AISI 304 Using Inductively Coupled Plasma Assisted DC Magnetron Sputtering Method

  • Jun, Shinhee;Kim, Junho;Kim, Sunkwang;You, Yong Zoo;Cha, Byungchul
    • 한국표면공학회지
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    • 제46권5호
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    • pp.187-191
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    • 2013
  • Niobium nitride (NbN) films were deposited on AISI 304 stainless steels by inductively coupled plasma (ICP) assisted dc magnetron sputtering method at different ICP powers, and the effects of ICP power on the phase formation, mechanical and chemical properties of the films were investigated. X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (FESEM) were used to analyze the crystal structure and micro-knoop hardness was used to measure the hardness of the films. Also, 3-D mechanical profiler and a ball-on-disk wear tester were used to measure the thickness of the films and to estimate wear characteristics, respectively. The thickness of the films decreased but their hardness increased with increasing ICP power, and it was confirmed that only cubic ${\delta}$-NbN(200) remained at high ICP power. At lower ICP powers, a mixture of the hexagonal ${\delta}^{\prime}$-NbN and cubic ${\delta}$-NbN phases was obtained in the films and the hardness decreased. The corrosion potential value increased gradually with increasing ICP power, but the changes of ICP power did not significantly influence the overall corrosion resistance.

The relationship between dental implant stability and trabecular bone structure using cone-beam computed tomography

  • Kang, Se-Ryong;Bok, Sung-Chul;Choi, Soon-Chul;Lee, Sam-Sun;Heo, Min-Suk;Huh, Kyung-Hoe;Kim, Tae-Il;Yi, Won-Jin
    • Journal of Periodontal and Implant Science
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    • 제46권2호
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    • pp.116-127
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    • 2016
  • Purpose: The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods: We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results: SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions: There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses.

The Effect of Genetically Modified Lactobacillus plantarum Carrying Bone Morphogenetic Protein 2 Gene on an Ovariectomized Rat

  • Jin, Eun-Sun;Kim, Ji Yeon;Yang, Jung-Mo;Kim, Jun-Sub;Min, JoongKee;Jeon, Sang Ryong;Choi, Kyoung Hyo;Moon, Gi-Seong;Jeong, Je Hoon
    • Journal of Korean Neurosurgical Society
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    • 제65권2호
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    • pp.204-214
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    • 2022
  • Objective : Osteoporosis result from age-related decline in the number of osteoblast progenitors in the bone marrow. Probiotics have beneficial effects on the host, when administered in appropriate amounts. This study investigated the effects of probiotics expressing specific genes, especially the effects of genetically modified bone morphogenetic protein (BMP)-2-expressing Lactobacillus plantarum CJNU 3003 (LP) on ovariectomized rats. Methods : Twenty-eight female Wistar rats (250-300 g, 12 weeks old) were divided into four groups : the sham (control), the ovariectomy (OVX)-induced osteoporosis group (OVX), the OVX and LP (OVX/LP), OVX and genetically modified BMP-2-expressing LP (OVX/LP with BMP) groups. The three groups underwent bilateral OVX and two of these groups were administered two different types of LP via oral gavage daily. At 16 weeks post-OVX, blood was collected from the heart and the bilateral tibiae were extracted and were scanned by ex-vivo micro-computed tomography and stained with hematoxylin-and-eosin (H&E) and Masson's trichrome stain for pathological assessment. The serum levels of osteocalcin (OC), rat C-telopeptide of type I collagen (CTX-I), BMP-2, and receptor activator of nuclear factor-ĸB ligand (RANKL) were measured. Results : The 3D-micro-computed tomography images showed that the trabecular structure in the OVX/LP with BMP group was maintained compared with OVX and OVX/LP groups. No significant differences were detected in trabecular thickness (Tb.Th) between control and OVX/LP with BMP groups (p>0.05). Furthermore, a tendency toward increased BMD, trabecular bone volume, Tb.Th, and trabecular number and decreased trabecular separation was found in rats in the OVX/LP with BMP groups when compared with the OVX and OVX/LP groups (p>0.05). The H&E and Masson's trichrome stained sections showed a thicker trabecular bone in the OVX/LP with BMP group compared with the OVX and OVX/LP groups. There was no difference in serum levels of OC, CTX and RANKL control and OVX/LP with BMP groups (p>0.05). In contrast, significant differences were found in OC and CTX-1 levels between the OVX and OVX/LP with BMP groups (p<0.05). Conclusion : Our results showed that the expression of genetically modified BMP-2 showed inhibition effect for bone loss in a rat model of osteoporosis.

중국(中國) 연변지구(延邊地區) 조선족(朝鮮族)마을의 구성(構成) 룡정시 지신향 장재촌을 대상으로 (Tie Spatial Structure of Ch'ang-ts'ai-ts'un Village A Case Study on a Rural Village of Korean Immigrants in Yen-pien Area of China)

  • 이규성
    • 건축역사연구
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    • 제3권1호
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    • pp.83-99
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    • 1994
  • Ch'ang-Ts'al-Ts'un is a rural Village near Lung-jing City in Yen-pien Korean Autonomous Province of China. It was formed about 100 years ago by Korean Immigrants and has been developed maintaing the characteristics of traditional Korean architecture. Therefore investigating the spatial structure of this village is a meanigful work to confirm and explore one branch of Korean architecture. This study aims at analyzing the spatial structure of the village using direct data collected from the field work and indirect data from books and maps. The field work consists of on-the-site survey of the village layout, interviews of residents, observation notes and photography. Ch'ang-Ts'ai-Ts'un is located 360-370 m high above the sea level and at the side of a long valley. A river flows in the middle of the valley and relatively flat arable land exists at the both sides of the river. The location of the village related to the surrounding river and mountains suggests that the site of the village was chosen according to Feng-Shui, Chinese and Korean traditional architectural theory. The main direction of the house layouts is South-western. The village has been growing gradually until today. Therefore it is meaningful to make the village layout before Liberation(1946 A.D.) because the characteristics of Korean architecture prevailed more in that period. The area of the previous village is limited to the west side of the creek. New houses were later added to the east of the creek, forming a 'New Village'. Previously the village was composed of 3 small villages: Up, Middle and Down. Also the main access roads connecting the village with the neighboring villages were penetrating the village transversely. Presently the main access road comes to the village longitudinally from the main highway located in front of the village. The retrospective layout shows the existence of well-formed Territory, Places and Axes, thus suggesting a coherent Micro-cosmos. The boundary of imaginery territory perceived by present residents could be defined by linking conspicous outside places sorrounding the village such as Five-mountains, Front-mountain, Shin-dong village, Standing-rock, Rear-mountain and Myong-dong village. Inside the territory there are also the important places such as Bus-stop, Memorial tower of patriots, Road-maitenance building and the village itself. And inside it 5 transverse and 1 longitudinal axes exist in the form of river, roads and mountains. The perceived spatial structure of the village formed by Places, Axes and Territory is geometrical and well-balanced and suggests this village is fit for human settlement. The administrative area of the village is about 738 ha, 27 % of which is cultivated land and the rest is mountain area. Initially the village and surrounndings were covered with natural forest But the trees have been gradually cut down for building and warning houses, resulting in the present barren and artificial landscape with bare mountains and cultivated land. At present the area of the village occupied by houses is wedge-shaped, 600 m wide and 220 m deep in its maximum. The total area of the village is $122,175m^{2}$. The area and the rate of each sub-division arc as follow. 116 house-lots $91,465m^{2}$ (74.9 %) Land for public buildings and shops $2,980m^{2}$ (2.4 %) Roads $17,106m^{2}$ (14.0 %) Creek $1,356m^{2}$ (1.1 %) Vacant spaces and others $9,268m^{2}$ (7.6 %) TOTAL $122,175m^{2}$ (100.0 %) Each lot is fenced around with vertical wooden pannels 1.5-1.8 m high and each house is located to the backside of the lot. The open space of a lot is sub-divided into three areas using the same wooden fence: Front yard, Back yard and Access area. Front and back yards are generally used for crop-cultivation, the custom of which is rare in Korea. The number of lots is 116 and the average size of area is $694.7m^{2}$. Outdoor spaces in the village such as roads, vacant spaces, front yard of the cultural hall, front yard of shops and spacse around the creek are good 'behavioral settings' frequently used by residents for play, chatting, drinking and movie-watching. The road system of the village is net-shaped, having T-junctions in intersections. The road could be graded to 4 categories according to their functions: Access roads, Inner trunk roads, Connecting roads and Culs-de-sac. The total length of the road inside the village is 3,709 m and the average width is 4.6 m. The main direction of the road in the village is NNE-SSE and ESE-WNW, crossing with right angles. Conclusively, the spatial structure of Ch'ang-Ts'ai-Ts'un village consists of various components in different dimensions and these components form a coherent structure in each dimension. Therefore the village has a proper spatial structure meaningful and appropriate for human living.

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PLD법에 의한 혼합된 희토류계$(Nd_{1/3}Eu_{1/3}Gd_{1/3})Ba_2Cu_3O_{7-x}$ 고온 초전도 박막 (Mixed rare earth $(Nd_{1/3}Eu_{1/3}Gd_{1/3})Ba_2Cu_3O_{7-d}$ thin films by PLD)

  • 고락길;배성환;정명진;장세훈;송규정;박찬;손명환;강석일;오상수;하동우;하홍수;김호섭;김영철
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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    • pp.3-3
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    • 2009
  • In order to investigate the possibility of using mixed rare earth $(Nd_{1/3}Eu_{1/3}Gd_{1/3})Ba_2Cu_3O_{7-x}$ (NEG123) as the superconducting layer of the HTS coated conductor, the NEG123 thin film was deposited epitaxialy on LAO(100) single crystal and IBAD_YSZ metal templates by pulsed laser deposition. Systematic studies were carried out to investigate the influences of deposition parameters of PLD on the micro structure, texture and superconducting properties of NEG-123 coated conductor. Deposition at oxygen partial pressure of 600 mTorr was needed to routinely obtain high quality NEG123 films with $J_c$'s (77K) over 2 MA/$cm^2$ and Tc's over 90K (${\Delta}T{\sim}2\;K$). We verified from magnetization study that the NEG123 has an improved in-field Jc as the field increases at temperatures between 10 K and 77 K compared with Gd123. The $J_c$ (77K, self field) and the value of onset $T_c$ of NEG123 thin film on LAO substrate was $4.0MA/cm^2$ and 92K, respectively. This is the first report, to the best of our knowledge, of coated conductors with NEG123 film as the superconducting layer which have Ic and Jc over 40 A/cm-width and 1.6 MA/$cm^2$ at 77K, self field. This study shows the possibility of using NEG123 film as the superconducting layer of the HTS coated conductor which can be used in high magnetic field power electric devices.

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