• 천문학회보
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• 제38권1호
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• pp.40.1-40.1
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• 2013

The HI ring serendipitously found in the Leo I galaxy group is unique in size in the Local Universe. It is ~200kpc in diameter with MHI~$1.67{\times}109M{\odot}$, surrounding a pair of early type galaxies M105 and NGC 3384. Its origin is still under debate whether it is the remnant of formation of a galaxy group (primordial) or formed from stripped material during galaxy-galaxy interaction (tidal origin). Intriguingly a number of dwarf galaxies have been identified along the gas ring (with or without optical counterpart). Various properties of these dwarf galaxies such as dark matter content, color, and/or metallicity will allow us to pin down the origin of this large scale HI ring. We have obtained a mosaicked CFHT MegaCam image and the EVLA HI cube of the large scale gas ring. In this work we present optical and gas properties of dwarf galaxies identified in the CFHT data.

• Journal of the Korean Wood Science and Technology
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• 제23권3호
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• pp.82-87
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• 1995

Anatomical characteristics of genus Platycarya, Juglans and Pterocarya of Juglandaceae occurring in Korea were described and coded based on the IAWA list. Juglandaceae are ring-porous or semi-ring-porous. Vessels have simple perforation plates and helical thickenings in some genus. Axial parenchyma cells were abundant, most apotracheal but rarely paratracheal and rays with 1-5 seriate. Platycarya is ring-porous wood with 2-3 rows of vessels in the pore zone. Helical thickenings were found only in small vessel of latewood. Axial parenchyma were commonly diffuse-in-aggregates or vasicentric. Rays 3-5 seriate. belonging to Kribs' heterogeneous II or III type with frequent occurrence of rhomboidal crystals. Juglans are semi ring-porous with few vessels in $mm^2$ and pores are commonly solitary. Axial parenchyma were diffuse-in-aggregate or marginal. Rays were mostly homocellular and 3-5 seriates. Pterocarya is similar to Juglans in anatomical features but the reticulate parenchyma consisting of 1 layer on transverse section and biseriate rays.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.860-866
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• 2022

An accurate prediction of the pressure drop along the flow paths is crucial in the design of advanced passive systems cooled by heavy liquid metal coolants. To date, a generic pressure drop correlation over spacer grids by Rehme has been applied extensively, which was obtained from substantial experimental data with multiple types of components. However, a few experimental studies have reported that the correlation may give large discrepancies. To provide a more reliable correlation for ring-type spacer grids, the current numerical study aims at figuring out the most critical factor among four hypothetical parameters, namely the flow area blockage ratio, number of fuel rods, type of fluid, and thickness of the spacer grid in the flow direction. Through a set of computational fluid dynamics simulations, we observed that the flow area blockage ratio dominantly influences the pressure loss characteristics, and thus its dependence should be more emphasized, whereas the other parameters have little impact. Hence, we suggest a new correlation for the drag coefficient as C_B = C_ν,m/ε^2.7, where C_ν,m is formulated by a nonlinear fit of simulation data such that C_ν,m = -11.33 ln(0.02 ln(Re_b)).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.215-216
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• 2008

Using the extensional vibration mode of PZT ring, a piezopump is successfully made. The PZT ring is polarized with thickness direction. The traveling extensional wave along the circumference of the ring is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic ring.

• 충청수학회지
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• 제24권3호
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• pp.427-436
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• 2011

In this paper, we first show that the pull-back morphism between two K-groups of the Steinberg varieties, obtained respectively from partial flag varieties and quiver varieties of type A, is a ring homomorphism with respect to the convolution product. Then, we prove that this ring homomorphism yields a property of compatibility between two certain convolution actions.

• 드라이브 ㆍ 컨트롤
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• 제12권2호
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• pp.21-26
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• 2015

In order to design a swash plate type pump for electro-hydrostatic actuators the performance of the hydrostatic piston shoe bearings in the low speed range needs to be examined, since the pump operates frequently at low speeds, compensating for position control errors as a control element. As a common practice, piston shoes are equipped with inner rings as an auxiliary element to enhance their tribological performance. In this paper, the effects of the inner rings of the piston shoes on the frictional loss and leakage flow rate were investigated, where three piston shoe models, with different inner ring shapes and different inlet orifice sizes, were integrated. The test results showed that a large inner ring and small inlet orifice were advantageous for reducing both the frictional loss and leakage flow rate; this could also be confirmed by computational analyses.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2023년도 춘계학술대회
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• pp.156-156
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• 2023

Salinity is a major abiotic stress that limits rice productivity in many regions of the world. In order to develop salt stress tolerant rice plants, genetic engineering is a promising approach. We characterized the molecular function of rice C3H2C3 as a really interesting new gene (RING). Oryza sativa RING finger protein H2-3 (OsRFPH2-3) was highly expressed in 100 mM NaCl. To identify the localization of OsRFPH2-3, we fused vectors that include C-terminal GFP protein (35S;;OsRFPH2-3-GFP). OsRFPH2-3 was expressed in the nucleus in rice protoplasts. An in vitro ubiquitin assay demonstrated that OsRFPH2-3 possessed E3-ubiquitin ligase activity. However, the mutated OsRFPH2-3 were not possessed any E3-ubiquitin ligase activity. Under salinity conditions, OsRFPH2-3-overexpressing plants exhibited higher chlorophyll, proline, SOD, POD, CAT, and soluble sugar contents and lower H₂O₂ accumulation than wild-type plants, supporting transgenic plants with enhanced salinity tolerance phenotypes. OsRFPH2-3-overexpressing plants exhibited low Na+ accumulation and Na+/K+ ratios in their roots. Theses results suggest that overexpression of OsRFPH2-3 can make plant insensitivity about salinity conditions.

• 해양환경안전학회지
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• 제27권2호
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• pp.369-376
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• 2021

전 세계적으로 환경오염 문제로 국제해사기구인 IMO(International Maritime Organization)에서는 이산화탄소 배출량과 관련된 지수인 EEDI(Energy Efficiency Design Index)를 만들어 새로 건조되는 선박들에 대한 규제를 적용하고 있다. 본 연구에서는 158k 원유운반선의 선형과 프로펠러 후류를 분석하여 새로운 형태의 에너지 저감 장치인 ring stator를 제안하였다. 최근의 선박들은 반류가 적은 즉 선미부 유속이 빠른 경향으로 발전되고 있어 덕트가 포함된 ESD(Energy Saving Device)는 저속비대선이라도 컨테이너선처럼 적용하기가 어렵다. 본 연구에서 제안한 ring stator는 이러한 점을 고려하여 새로이 개발된 장치로써 자항 성능 향상 뿐 아니라 저항 성능의 최소화를 목표로 설계를 진행하였다. Star-CCM+의 상용 프로그램을 활용하여 CFD 해석을 통해 설계한 ring stator의 성능을 확인하였고 최종 제시한 설계안에 대해 약 3.4 %의 추진 효율 개선 효과가 있음을 확인하였다. 설계된 ring stator에 대한 실험과의 비교 등을 통해 성능 검증 및 보다 정도 높은 최적화에 대한 연구를 추후 수행할 계획이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.212-213
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• 2008

This paper describes the analysis of the device characteristics of the NPT type 1200V Insulated gate Bipolar Transistor. In case of NPT type IGBT devices, optimized n-epi layer thickness and concentration is important to obtain low on-state voltage and breakdown voltage characteristics. In this paper, we analyzed on-state and off-state characteristics of NPT type IGBT. Breakdown voltage of designed IGBT was higher than 1200V when we optimized Field Limiting Ring structures. And also, on-state voltage characteristics was shown less then 2.5V at 25A of drain current.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.117-121
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• 2001

A numerical simulation was conducted to investigate the effect of height position of Rushton type Impeller in the fermentation. The computational method was based on the CFX code. The simulation was performed for 3 height differences(25, 30, 35mm) between Rushton type impeller and bottom of fermentation. The instantaneous flow fields showed that the bulk flow consisted of large scale vortices. However the main flow results showed that the formation of ring vortices above and below the impeller depended on the height of the impeller.