• 한국정밀공학회지
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• 제22권1호
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• pp.167-174
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• 2005

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• Journal of Microbiology and Biotechnology
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• 제27권6호
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• pp.1171-1179
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• 2017

Butanol is a promising alternative to ethanol and is desirable for use in transportation fuels and additives to gasoline and diesel fuels. Microbial production of butanol is challenging primarily because of its toxicity and low titer of production. Herein, we compared the transcriptome and phenome of wild-type Escherichia coli and its butanol-tolerant evolved strain to understand the global cellular physiology and metabolism responsible for butanol tolerance. When the ancestral butanol-sensitive E. coli was exposed to butanol, gene activities involved in respiratory mechanisms and oxidative stress were highly perturbed. Intriguingly, the evolved butanol-tolerant strain behaved similarly in both the absence and presence of butanol. Among the mutations occurring in the evolved strain, cis-regulatory mutations may be the cause of butanol tolerance. This study provides a foundation for the rational design of the metabolic and regulatory pathways for enhanced biofuel production.

• Plant Biotechnology Reports
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• 제4권4호
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• pp.243-251
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• 2010

Nitric oxide (NO) has been shown to be involved in diverse physiological processes in microbes, animals and plants. In this study, the involvement of NO in the development and possible roles in oxidative stress protection of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Samrack-ulgari) seedlings were investigated. Exogenous application of sodium nitroprusside (SNP) retarded root elongation, while increasing lateral root formation of Chinese cabbage. Plants showed no signs of external stress due to SNP application in true leaves. Cotyledons of 3-week-old Chinese cabbage plants were found to be highly sensitive to SNP application. Treated cotyledons displayed rapid tissue collapse and associated cell death. Although SNP application reduced root growth under normal growth conditions, it also enhanced methyl viologen (MV)-mediated oxidative stress tolerance. Analysis of SNP application to Chinese cabbage leaf disks, revealed SNP-induced tolerance against oxidative stresses by MV and $H_2O_2$, and evidence includes prevention of chlorophyll loss, superoxide anion (${O_2}^-$) accumulation and lipid peroxidation. This report supports a role for nitric oxide in modulating early seedling development, programmed cell death and stress tolerance in Chinese cabbage.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.46-52
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• 2003

In this paper, we fabricated PRT(platinum resistance thermometers) with the trimming technology using high fine laser system. U. V.(wavelength： 355nm) laser was mainly used for adjusting Pt thin films resistors to 100Ω at 0$^{\circ}C$. Internationally, the accepted A-class tolerance of temperature sensor is ${\pm}$0.06Ω at 0$^{\circ}C$. according to DIN EN 60751. The width of trimmed lines was about 10$\mu\textrm{m}$ and the best trimming conditions of Pt thin films were power : 37mW, frequency : 200Hz and bite size：1.5$\mu\textrm{m}$. And 96 resistors, fabricated by photolithography and etching process, have 79∼90Ω and 91∼102Ω as the proportion of 45.7% and 57.3%, respectively. As result of sitting Pt thin films resistors to the target value(109.73Ω at 25$^{\circ}C$), 82.3% of all resistors had the tolerance within ${\pm}$0.03Ω and the others(17.7％) were within ${\pm}$0.06Ω of A-class tolerance. The PRTs which wore fabricated in this research had excellent characteristics as follows； high accuracy, international standard TCR(temperature coefficient of resistance) value, long-term stability, wide temperature range, good linearity and repeatability, rapid response time, etc.

• 정보저장시스템학회논문집
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• 제6권1호
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• pp.12-17
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• 2010

Thermally-assisted magnetic recording (TAMR) is a potentially promising approach to increase the storage density of hard disk drive (HDD). However, TAMR has some issues such as temperature effects, media problems, thermal deformation and light delivery. In this research, we focused on light delivery. One of the powerful methods to deliver the light from laser diode to recording medium is the use of an optical fiber and a specially designed prism. However, the TAMR with optical fiber may have some flyability problems induced by the mounted optical fiber and prism. Also, the TAMR suspension using an optical fiber has high vertical and pitch stiffness. Therefore, p-torque is greatly increased by the optical fiber. Also, flying height (FH) of the slider with TAMR suspension can be largely changed by p-torque. Therefore, in this paper, we focus on the pitch static attitude (PSA) tolerance and the FH by PSA of the TAMR suspension. The FH is investigated using various errors and the PSA tolerance for TAMR suspension is proposed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.245-248
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• 2000

Modern aircraft composite structures are designed using a damage tolerance philosophy. This design philosophy envisions sufficient strength and structural integrity of the aircraft to sustain major damage and to avoid catastrophic failure. The only reasonable way to treat on the same basis all the conditions and uncertainties participating in the design of damage tolerant composite aircraft structures is to use the probability-based approach. Therefore, the model has been developed to assess the probability of structural failure (POSF) and associated risk taking into account the random mechanical loads, random temperature-humidity conditions, conditions causing damages, as well as structural strength variations due to intrinsic strength scatter, manufacturing defects, operational damages, temperature-humidity conditions. The model enables engineers to establish the relationship between static/residual strength safety margins, production quality control requirements, in-service inspection resolution and criteria, and POSF. This make possible to estimate the cost associated with the mentioned factors and to use this cost as overall criterion. The methodology has been programmed into software.

• 미생물학회지
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• 제55권3호
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• pp.300-302
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• 2019

제천에서의 콩 근권 시료로부터 분리한 Glutamicibacter halophytocola DR408 균주는 내건성 식물생장촉진력을 보이고 있다. 본 연구에서 DR408 균주의 완전한 유전체 서열을 해독한 결과, 유전체의 크기는 3.77 Mbp였으며, G + C 함량이 60.2%였다. 또한 총 3,352개의 유전자 서열과 65개의 tRNA, 19개의 rRNA, 3개의 ncRNA가 존재하였다. 유전체 분석을 통해 식물의 내건성을 향상시킬 수 있는 삼투질 합성과 식물생장촉진 효소를 코딩하는 유전자를 다수 포함하는 것을 확인하였다.

• Genomics & Informatics
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• 제19권4호
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• pp.45.1-45.8
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• 2021

Brassica napus is the third most important oilseed crop in the world; however, in Korea, it is greatly affected by cold stress, limiting seed growth and production. Plants have developed specific stress responses that are generally divided into three categories: cold-stress signaling, transcriptional/post-transcriptional regulation, and stress-response mechanisms. Large numbers of functional and regulatory proteins are involved in these processes when triggered by cold stress. Here, our objective was to investigate the different genetic factors involved in the cold-stress responses of B. napus. Consequently, we treated the Korean B. napus cultivar Naehan at the 4-week stage in cold chambers under different conditions, and RNA and cDNA were obtained. An in silico analysis included 80 cold-responsive genes downloaded from the National Center for Biotechnology Information (NCBI) database. Expression levels were assessed by reverse transcription polymerase chain reaction, and 14 cold-triggered genes were identified under cold-stress conditions. The most significant genes encoded zinc-finger proteins (33.7%), followed by MYB transcription factors (7.5%). In the future, we will select genes appropriate for improving the cold tolerance of B. napus.

• 한국정보과학회논문지:정보통신
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• 제34권5호
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• pp.305-315
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• 2007

광대역통합망(Broadband Convergence Network, BcN)은 전화, 인터넷, 방송 네트워크 등 개별적으로 운용되어오던 네트워크들을 하나의 통합망으로 구축, 구동, 관리하는 차세대 네트워크이다. 개별적으로 운용되어오던 네트워크들이 하나로 통합되면서 서비스 별로 산재해 있던 네트워크의 위협요소는 하나의 통합망에서 더욱더 위력적인 요소로 다가올 것이다. 본 논문에서는 BcN 서비스들이 악성 공격에 대해 지속적인 서비스 운영을 보장하기 위한 네트워크 디자인 방법을 제안한다. 본 연구는 서비스 시간과 공간 중요도를 바탕으로 BcN 필수 서비스 구성요소를 도출하고, 구성요소의 형태에 따라 서버 형태, 게이트웨이 형태, 복합 형태의 세 가지 타입으로 구분한다. BcN 환경에서 발생 가능한 공격 시나리오들을 통해 BcN 필수 서비스의 침입감내 기술 적용 방안을 모색한다. 이를 통하여 하드웨어 중복성과 Policy 서버의 보안 정책 설정을 통한 BcN 침입감내 네트워크 디자인을 제안한다. 본 논문에서는 제안한 프로토타입 네트워크를 BcN에 적용하기 전과 적용한 후 BcN에서 공격이 발생되었을 때의 시나리오를 통하여 BcN의 침입감내를 가능케 함을 보인다.

• Journal of Ecology and Environment
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• 제38권4호
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• pp.505-515
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• 2015

The objectives of this study were to determine the effects of stream nutrient regime, N:P ratios and suspended solids on fish tolerance/trophic compositions and stream ecosystem health, based on multi-metric model, during 2008-2013. Also, stream ecosystem health was evaluated in relation to chlorophyll-a (CHL) as a measure of algal productivity or indicators of trophic state to water chemical parameters. Total number of sampled fish species were 50 and showed a decreasing trend from 2008 to 2013. The minnow of Zacco platypus, based on the catch per unit effort (CPUE), was the most dominant species (25.9%) among the all species. Spatial heterogeneity was evident in the fish tolerance guilds that showed the dominance of sensitive species (89%) in the headwaters (S1) and the dominance of tolerant species (57%) in the urban. These conditions were directly influenced by concentrations of nutrients and organic matter (COD). The N:P ratios, as a barometer of water pollution, had a negative linear function (R² = 0.40, P < 0.01) with CHL, and the ratios had an important role in changes of COD concentration (R² = 0.40, P < 0.01). Under the circumstances, the N:P ratio directly influenced the relative proportions of fish trophic/tolerance compositions. According to the regression analysis of omnivore (O_m) and insectivore sp. (I_n) on total nitrogen and total phosphorus, nitrogen had no significant influences (P > 0.05) to the two compositions, but phosphorus influenced directly the two guilds [slope (a) = -32.3, R² = 0.25, P < 0.01 in the I_n; a = 40.7, R² = 0.19, P < 0.01 in the O_m]. Such water chemistry and fish trophic guilds determined the stream ecosystem health, based on the multi-metric fish model.