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A Study on the Reliability Prediction for Space Systems (우주 시스템의 신뢰성 예측에 관한 연구)

  • Yu, Seung-U;Lee, Baek-Jun;Jin, Yeong-Gwon
    • Aerospace Engineering and Technology
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    • v.5 no.2
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    • pp.227-239
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    • 2006
  • Reliability prediction provides a rational basis for design decisions such as the choice between alternative concepts, choice of part quality levels, derating factors to be applied, use of proven versus state-of-the-art techniques, and other factors. For this reasons, reliability prediction is essential functions in developing space systems. The worth of the quantitative expression lies in the information conveyed with the numerical value and the use which is made of that information and reliability prediction should be initiated early in the configuration definition stage to aid in the evaluation of the design and to provide a basis for item reliability allocation (apportionment) and establishing corrective action priorities. Reliability models and predictions are updated when there is a significant change in the item design availability of design details, environmental requirements, stress data, failure rate data, or service use profile. In this paper, the procedure, selection of reliability data and methods for space system reliability prediction is presented.

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A Basic Study on Torsion Shear Tests in Soils (흙의 비틀림전단시험에 관한 기초적 연구)

  • 홍원표
    • Geotechnical Engineering
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    • v.4 no.1
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    • pp.17-28
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    • 1988
  • Among several types of element tests to predict soil behalf.iota in a laboratory, the torsion shear apparatus, in which the directions of principal stresses could be rotated during shearing, wra explained. In this study, this torsion shear apparatus was improved so as to be used in tests on clay specimens . And some undrained torsion shear tests u.ere performed on remolded specimens of Ko-consolidated clay to investigate the influence of reorientation of the principal stress directions on the stress-strain behavior The soil behavior by the torsion shear apparatus without torque was compared It.ith that by the conventional triaxial compression tests . The stress path, provided by both vertical loads and torque during torsion shear tests, has much effect on the stress-strain behavior, the pore pressure and the effective principal stress ratio . The rotation angle of the principal stress and the b-value were gradually increased with increasing shear strain, but converged to the values at failure.

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A Study on the Slope Stability Analysis by Shearing Reinforcement of Vegetation Roots -Focused on the Pinus Koraiensis Roots- (식생뿌리의 전단강도 보강에 의한 사면안전율 해석 -잣나무 뿌리를 중심으로-)

  • 조주형;이종성
    • Journal of the Korean Institute of Landscape Architecture
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    • v.27 no.5
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    • pp.80-93
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    • 2000
  • This study measured the shearing resistance of the roots of the Pinus Koraiensis by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. On the basis of the shearing resistance value calculated through such a process the factor of safety(Fs) was comparatively presented by using the simplified Janbu Method in PCSTABL5M, the slop-analyzing software which had been developed in Purdue University of the U.S.A according to the shape of a slope and the type of soil. The results to have measured a stress and the factor of safety(Fs) by experiment are as follows. 1) The mean root diameter of the Pinus Koraiensis used for this experiment was 2.483mm and the mean tensile stress was calculated as 422.846(kgf/$\textrm{cm}^2$). In the strain ratio of material and the elastic modulus was measured 7.8%, 9,291.92(kgf/$\textrm{cm}^2$). 2) The shearing strength including the resistance of soil and root is expressed as Rt=C+Cr+$\sigma$.tan . ΔCr(kg/$\textrm{cm}^2$) of the shearing resistance calculated by estimating the areal ratio of roots at 10 is 0.253(kgf/$\textrm{cm}^2$). 3) As the result of making an analysis of the natural slope stability by the soil parameter, the factor of safety(Fs) was calculated at 1.795 in CL, and the stability analysis of the root reinforcement slope, Fs was calculated at 1.952. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

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Epitaxial Growth of ZnO Nanowires on Sapphire (001) Substrates Using a Hydrothermal Process (수열합성법을 이용한 산화아연 나노와이어의 에피택시 성장)

  • Ham, Daseul;Jeong, Byeong Eon;Yang, Myeong Hun;Lee, Jong Kwan;Choi, Young Bin;Kang, Hyon Chol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.7
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    • pp.502-509
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    • 2018
  • Epitaxial ZnO nanowires (NWs) were synthesized on sapphire (001) substrates using a hydrothermal process. The effects of the pH value of the precursor solution on the structural and optical properties of the resulting NWs was studied. The epitaxial relationship and the domain matching configuration between the sapphire (001) substrate and the as-grown ZnO NWs were determined using synchrotron X-ray diffraction measurements. The (002) plane of $w{\ddot{u}}rtzite$ ZnO NW grows in the surface normal direction parallel to the sapphire (001) direction. However, three types of in-plane domain matching configurations were observed, such as the on-position, $30^{\circ}$-rotated position, and ${\pm}8.5^{\circ}$-rotated position relative to the on-position, which might be attributed to inheriting the in-plane domain configuration of the ZnO seed layer.

The Comparative Study for Green Building model house design in Korea (국내 친환경 건축 모델하우스에 대한 비교 연구)

  • Kang, Yeon-Joo;Kim, Moon-Duck
    • Korean Institute of Interior Design Journal
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    • v.21 no.6
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    • pp.212-223
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    • 2012
  • The "Eco-friendly", "Green" concepts was began around 1992 after the Rio Environmental Summit, and the need for sustainable development globally widespread. The green building certification system was began around 2000 and the concept of green building was started in the late 1990s. The green building, which welcomes a period of radical change, is for the survival of the Earth "climate change" and reducing energy consumption in building sector. In this architecture of eco-friendly concept, the green building is rapidly expanding and existing as a ecological environment preservation. Moreover, the realization of zero energy house is to mandate for new buildings in 2025. The aim of further eco-friendly is through the prior ecosystems to restore and product energy for the 9 Green Building model houses in this paper. Building in the concept of ecology is to show about change into 7R's from the 3R's. The "Reduce", "Reuse", "Recycle" consisting of "3R's" is correlated with the traditional to the present Green Building Design. U.S. NCARB (National Council of Architectural Registration Boards) change into the concept of 7R's as "Receive", "Restore", "Respect" and "Remember", added to "3R's". In this paper, the 9 Green Building model houses do not meet the criteria of 7R's. But, the Green Tomorrow of Samsung C & T Corporation meet the 6 criteria for 7R's. This company is most comfortable at low carbon Green Building model houses. Conclusionally, introduction of eco-friendly technologies and amenities for the health of human and natural community life is to advance eco-friendly construction and enhance brand value of housing. By the way, The problem of eco-friendly architecture is initial investment and maintenance. Therefore, eco-friendly architecture and government has to try solving of this difficulty.

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A Study on the Expression of the Publicness on Public Branch Library Design - Focus on the Maricopa County, USA - (브랜치 도서관디자인의 공공성 표현에 관한 연구 - 미국 마리코파 카운티를 중심으로 -)

  • Son, Kwang-Ho
    • Korean Institute of Interior Design Journal
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    • v.21 no.6
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    • pp.271-279
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    • 2012
  • Among the community-based cultural facilities, public libraries are places for social and educational purpose that improve the education of the resident, the expansion of the basic cultural education, communication between the members of society, and the accumulations and preservations of the culture. Public libraries should be a local cultural facility that expresses the value of a community. This study aims to analyze the design expression of publicness in a public branch library as a community-based cultural space through the study of branch library in the U.S. This study focused on the most future-oriented and innovative Ten New Landmark Libraries in the United States selected by Library Journal magazine in 2011. Among the selected libraries, three branch libraries which belongs Arizona Maricopa County were included in the study. The results of this study are as follows. First, the sites of the branch libraries vary geographically, but the libraries increase accessibility are caused by unique appearances and design concept of intellectual interest. Second, the floor plan shows the separation of meeting rooms and faculty space from the public space and has visual and spatial open space by high ceiling of the reading room. Third, multi-functional public space for residents are meeting rooms, the external patios for reading, galleries, cafes, libraries-shops which provides a variety of cultural programs, activities, and the opportunity to socialize neighbors. Fourth, branch Libraries have unique designs that harmonizes with nearby places to reflect locality, giving the locals a sense of pride in their community. Fifth, concrete brick and metal panel were used as finishing material for the practicality of maintenance. In particular, transparent glass envelope allows the locals to stay for long time due to openness and brightness of space.

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A New Thpe of Recurrent Neural Network for the Umprovement of Pattern Recobnition Ability (패턴 인식 성능을 향상시키는 새로운 형태의 순환신경망)

  • Jeong, Nak-U;Kim, Byeong-Gi
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.2
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    • pp.401-408
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    • 1997
  • Human gets almist all of his knoweledge from the recognition and the accumulation of input patterns,image or sound,the he gets theough his eyes and through his ears.Among these means,his chracter recognition,an ability that allows him to recognize characters and understand their meanings through visual information, is now applied to a pattern recognition system using neural network in computer. Recurrent neural network is one of those models that reuse the output value in neural network learning.Recently many studies try to apply this recurrent neural network to the classification of static patterns like off-line handwritten characters. But most of their efforts are not so drrdtive until now.This stusy suggests a new type of recurrent neural network for an deedctive classification of the static patterns such as off-line handwritten chracters.Using the new J-E(Jordan-Elman)neural network model that enlarges and combines Jordan Model and Elman Model,this new type is better than those of before in recobnizing the static patterms such as figures and handwritten-characters.

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Human Risk Assessment of Perchloroethylene Considering Multi-media Exposure (다매체 노출을 고려한 Perchloroethylene의 인체위해성평가연구)

  • Seo, Jungkwan;Kim, Taksoo;Jo, Areum;Kim, Pilje;Choi, Kyunghee
    • Journal of Environmental Health Sciences
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    • v.40 no.5
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    • pp.397-406
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    • 2014
  • Objectives: Perchloroethylene (PCE) is a volatile chemical widely used as a solvent in the dry-cleaning and textile processing industries. It was evaluated as Group 2 "probably carcinogenic to humans" by the Integrated Risk Information System (IRIS) of the United State Environmental Protection Agency (U.S. EPA) in 2012. In order to provide a scientific basis for establishing risk management measures for chemicals on the national priority substances list, aggregate risk assessment was conducted for PCE, included in the top-10 substances. Methods: We conducted the investigation and monitoring of PCE exposure (e.g., exposure scenario, detection levels, and exposure factors, etc.) and assessed its multi-media (e.g., outdoor air, indoor air, and ground water) exposure risk with a deterministic and probabilistic approach. Results: In human risk assessment (HRA), the level of human exposure was higher in the younger age group. The exposure level through inhalation at home was the highest among the exposure routes. Outdoor air or uptake of drinking water represented less than 1% of total contributions to PCE exposure. These findings suggested that the level of risk was negligible since the Hazard Index (HI) induced by HRA was below one among all age groups, with a maximum HI value of 0.17 when reasonable maximum exposure was applied. Conclusion: In conclusion, it was suggested that despite low exposure risk, further studies are needed considering main sources, including occupational exposure.

Attenuation of Anemia by Relmα in LPS-Induced Inflammatory Response

  • Lee, Mi-Ran
    • Journal of the Korea Society of Computer and Information
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    • v.23 no.10
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    • pp.135-141
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    • 2018
  • In this paper, we propose to evaluate the effect of resistin-like molecule alpha ($Relm{\alpha}$) on the progression of anemia of inflammation. Anemia of inflammation is a common feature of inflammatory disorders, including chronic kidney disease, infections, and rheumatoid arthritis. $Relm{\alpha}$ is highly up-regulated in various inflammatory states, especially those involving asthma, intestinal inflammation, and parasitic diseases, and regulates the pathogenesis of those diseases. However, the role of $Relm{\alpha}$ in anemia of inflammation is unknown. To explore the roles of $Relm{\alpha}$ in anemia of inflammation in vivo, we generated mouse model of the disease by injecting 0.25 mg/kg lipopolysaccharides (LPS) intraperitoneally into $Relm{\alpha}-deficient$ and wild-type (WT) mice daily for 10 days. Research data was expressed as differences between LPS-treated $Relm{\alpha}-deficient$ and WT mice by a two-tailed non-parametric Mann-Whitney U-test using GraphPad Instat program. The results of the study are as follows: LPS-treated $Relm{\alpha}-deficient$ mice had significantly (p<0.05) lower hemoglobin contents, hematocrit levels and red blood cell indices including mean corpuscular volume, mean corpuscular hemoglobin than WT controls. This decrease was accompanied by significant (p<0.05) increase in total white blood cell and monocyte counts in the blood. However, there was no significant difference in mRNA levels of hepatic hepcidin and renal erythropoietin between the two animal groups. Taken together, these results indicates that $Relm{\alpha}$ deficiency exacerbates the anemia by increasing inflammation, suggesting therapeutic value of $Relm{\alpha}$ in the treatment of anemia of inflammation.

Pulse Wave Velocity Measured by Radial Artery Clip-type Pulsimeter Equipped with a Hall Device and Electrocardiogram (홀소자가 구비된 요골동맥 집게형맥진기와 심전도로 측정된 맥파전달속도)

  • Lee, Kyu-Hwan;Lee, Sang-Suk
    • Journal of the Korean Magnetics Society
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    • v.23 no.4
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    • pp.130-134
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    • 2013
  • The clip-type pulsimeter equipped with a magnetic sensing Hall device and the most popular body sign of the electrocardiogram (ECG) were investigated in order to analyze the pulse wave velocity (PWV). The PWV simultaneously calculated by means of time difference between the maximum peak of ECG pulse wave and the starting point of radial artery pulse wave, and distance difference between the heart position and the radial wrist position. The PWV analyzed from the clinical data was a wider scope of 5~7 m/s with an average value of 6 m/s. By the prediction of blood vessel's elasticity from the analysis of PWV, it may be useful for developing an oriental-western diagnostic medical signal device for a U-health-care system in the future.