• 전자통신동향분석
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• 제17권3호통권75호
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• pp.87-94
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• 2002

1990년대 중반 이후, 우리나라 뿐만 아니라 세계적으로 이동통신시장이 급격히 성장하고 있다. 이에 따라 고정전화에서 이동전화로 통화할 때 내는(LM 통화요금)의 적정성을 둘러싸고 사업자간의 의견 대립이 증가하면서, 이 요금의 인하 문제가 전 세계적으로 정보통신 산업계의 중요한 이슈로 등장하고 있다. 최근 영국의 규제 기관인 OFTEL은 이동통신 사업자들에게 LM 착신 접속요금을 인하하기 위한 권고 안을 발표하였다. 본 논문에서는 영국의 현행 LM 요금제도의 현황과 OFTEL이 제안한 권고 안의 주요 내용 및 이 안에 대한 이동통신 사업자들의 반응을 살펴보고, 이어서 우리나라 LM 요금정책에의 시사점을 제시하고자 한다.

• 항공우주
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• 제59권
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• pp.32-35
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• 1998

미국의 에어즈사는 현재 LM-200 로드마스터라는 기종을 개발중에 있다. 에어즈사가 비즈니스용 항공기 메이커여서 LM-200도 역시 비즈니스기지만 그 구조와 성능이 매우 재미있고 용도가 매우 광범위할 것으로 보여 이색 항공기의 하나로 소개하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2508-2512
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• 2012

Cold shock proteins (CSPs) are a family of proteins induced at low temperatures. CSPs bind to single-stranded nucleic acids through the ribonucleoprotein 1 and 2 (RNP 1 and 2) binding motifs. CSPs play an essential role in cold adaptation by regulating transcription and translation via molecular chaperones. The solution nuclear magnetic resonance (NMR) or X-ray crystal structures of several CSPs from various microorganisms have been determined, but structural characteristics of psychrophilic CSPs have not been studied. Therefore, we optimized the purification process to obtain highly pure Lm-Csp and determined the three-dimensional structure model of Lm-Csp by comparative homology modeling using MODELLER on the basis of the solution NMR structure of Bs-CspB. Lm-Csp consists of a ${\beta}$-barrel structure, which includes antiparallel ${\beta}$ strands (G4-N10, F15-I18, V26-H29, A46-D50, and P58-Q64). The template protein, Bs-CspB, shares a similar ${\beta}$ sheet structure and an identical chain fold to Lm-Csp. However, the sheets in Lm-Csp were much shorter than those of Bs-CspB. The Lm-Csp side chains, E2 and R20 form a salt bridge, thus, stabilizing the Lm-Csp structure. To evaluate the contribution of this ionic interaction as well as that of the hydrophobic patch on protein stability, we investigated the secondary structures of wild type and mutant protein (W8, F15, and R20) of Lm-Csp using circular dichroism (CD) spectroscopy. The results showed that solvent-exposed aromatic side chains as well as residues participating in ionic interactions are very important for structural stability. Further studies on the three-dimensional structure and dynamics of Lm-Csp using NMR spectroscopy are required.

• 생명과학회지
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• 제12권6호
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• pp.812-820
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• 2002

이 연구는 주변의 김치들을 수거하여 젖산에 내성을 가진 Leuconostoc mesenteroides을 선택배지를 이용하여 분리하고, 지방산 조성을 분석하여 동정한 결과, Leuconostoc mesenteroides LM3균주로 동정했다. 이어서 그의 성장패턴을 관찰하고, 유도기와 지수성장기에서 젖산을 첨가한 결과 성장저해가 일어났음을 확인했으며, 젖산의 최종농도가 0.4%이상인 배지에서는 성장속도가 느려짐을 알았다. 그리고 정지기시작단계에서 고농도의 젖산을 단시간 처리하였을 때, 대조균주가 생존하지 못하는 4%농도에서도 Leuconostoc mesenteroides LM3군주가 생존하는 것을 확인하여 산에 대한 내성이 뛰어남을 알 수 있었다. 이에 trehalose 농도의 변화, 그리고 trehalase와 ATPase 활성을 측정하였고, 이를 통해 젖산에 의한 세포내의 변화를 관찰하였다. 그 결과, 각 성장시기별로 0.6% 젖산을 첨가했을 때 Leuconostoc mesenteroides LM3균주가 trehalose 축적률이 높아졌으나 trehalase활성엔 큰 변화가 없었다. ATPase 활성은 감소하는 경향을 보였으나 시기별 활성은 일정하였고, 세포내 pH를 측정한 결과 Leuconostoc mesenteroides LM3균주는 pH 6으로 일정하게 유지되었다.

• 대한기계학회논문집A
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• 제40권2호
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• pp.199-206
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• 2016

LM 볼가이드는 구름접촉을 갖는 이송시스템의 핵심요소로서 공작기계, 반도체 장비, 로봇 등 정밀기계에 널리 사용된다. 그러나 LM 볼가이드에서 발생하는 마찰력은 마찰열을 유발하여 위치 정도를 저하시키고 강성과 예압 변화를 야기한다. 이런 영향을 정확하게 분석하여 정밀 기계설계에 응용하기 위해서는 마찰력 모델의 정식화가 요구된다. 본 논문에서는 구름마찰, 점성마찰, 슬립마찰을 고려한 LM 볼가이드의 정확한 마찰력 모델을 유도한다. 그리고 다양한 조립, 부하 및 속도 조건에서 실험을 수행하여 마찰력 모델의 신뢰성을 검증하고, 마찰력 모델로부터 마찰 성분의 영향력을 분석한다.

• Journal of Microbiology and Biotechnology
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• 제29권5호
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• pp.704-712
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• 2019

Although nanometric dead Lactobacillus plantarum has emerged as a potentially important modulator of immune responses, its underlying mechanism of action has not been fully understood. This study aimed to identify the detailed biochemical mechanism of immune modulation by micronized and heat-treated L. plantarum LM1004 (MHT-LM1004, <$1{\mu}m$ in size). MHT-LM1004 was prepared from L. plantarum LM1004 via culture in a specifically designed membrane bioreactor and heat treatment. MHT-LM1004 was shown to effectively induce the secretion of $TNF-{\alpha}$ and IL-6 and the mRNA expression of inducible nitric oxide synthase (iNOS). MHT-LM1004 enhanced the expression of TLR-2, phosphorylation of MAPKs (ERK), and nuclear translocation of $NF-{\kappa}B$ in a dose-dependent manner. Oral administration of MHT-LM1004 ($4{\times}10^9$ or $4{\times}10^{11}cells/kg$ mouse body weight) increased the splenocyte proliferation and serum cytokine levels. These results suggested that MHT-LM1004 effectively enhances early innate immunity by activating macrophages via the TLR-2/MAPK/$NF-{\kappa}B$ signalling pathway and that this pathway is one of the major routes in immune modulation by the Lactobacillus species.

• 한국축산식품학회지
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• 제42권6호
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• pp.1031-1045
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• 2022

Postbiotics are defined as probiotics inactivated by heat, ultraviolet radiation, sonication, and other physical or chemical stresses. Postbiotics are more stable than probiotics, and these properties are advantageous for food additives and pharmacological agents. This study investigated the immunostimulatory effects of heat-treated Lactiplantibacillus plantarum LM1004 (HT-LM1004). Cellular fatty acid composition of L. plantarum LM1004 isolated form kimchi was analyzed by gas chromatography-mass spectrometry detection system. The nitric oxide (NO) content was estimated using Griess reagent. Immunostimulatory cytokines were evaluated using enzyme-linked immunosorbent assay. Relative protein expressions were evaluated by western blotting. Phagocytosis was measured using enzyme-labelled Escherichia coli particles. L. plantarum LM1004 showed 7 kinds of cellular fatty acids including palmitic acid (C16:0). The HT-LM1004 induced release of NO and upregulated the inducible NO synthase in RAW 264.7 macrophage cells. Tumor necrosis factor-α and interleukin-6 levels were also increased compared to control (non-treated macrophages). Furthermore, HT-LM1004 modulated mitogen-activated protein kinase (MAPK) subfamilies including p38 MAPK, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase. Therefore, these immunostimulatory effects were attributed to the production of transcriptional factors, such as nuclear factor kappa B (NF-κB) and the activator protein 1 family (AP-1). However, HT-LM1004 did not showed significant phagocytosis of RAW 264.7 macrophage cells. Overall, HT-LM1004 stimulated MAPK/AP-1 and NF-κB expression, resulting in the release of NO and cytokines. These results will contribute to the development of diverse types of food and pharmacological products for immunostimulatory agents with postbiotics.

• 응용통계연구
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• 제19권3호
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• pp.461-479
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• 2006

본 논문에서는 이원오차성분을 갖는 패널회귀모형에서 모형식별을 위하여 LM 검정통계량을 유도하고 검정통계량의 연산을 위하여 인공회귀방법(Double-Length Artificial Regression, DLR)을 이용한다. 모의 실험 결과, 소표본의 경 우에는 Outer-Product Gradient(OPG)에 근거한 LM 검정통계량은 유위수준이 과대기각하는 경향을 보인 반면 DLR에 근거한 LM 검정통계량은 명목유의수준을 잘 유지하고 검정력도 높게 나타났다.

• 한국산업정보학회논문지
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• 제23권3호
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• pp.131-142
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• 2018

Since income growth rate and poverty level are related, there is a possibility that the poverty rate may converge in the long run steady state as well. If the poverty rate converges, then for this study the state that begins with the high poverty rate would have a higher poverty reduction rate. To examine the convergence of poverty rate among the US states, this study uses two times series methodologies. First, in order to prevent the power loss from ignoring the structural break when testing for a unit root in a single time series, this study employs the newly developed panel LM unit root tests with level and trend shifts. The results of unit root tests of the log of poverty rate without allowing for structural breaks show that twenty six states reject the null hypothesis of unit root test for the ADF test, twenty five states for the LM test, and thirty five states for the RALS-LM test. The result of unit root tests that allow one structural break shows that the null hypothesis of a unit root test is rejected for twenty two states with the LM test, and thirty three states with the RALS-LM test. This supports poverty rates are converging among US states.

• 한국정밀공학회지
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• 제32권5호
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• pp.423-429
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• 2015

Linear motion (LM) ball guides have good accuracy and high efficiency. They are widely applied for precision machinery such as machine tools, semiconductor fabrication machines and robots. However, friction force incurs heat between the balls and grooves. Thermal expansion due to the heat deteriorates stiffness and accuracy of the LM ball guides. For accurate estimation of stiffness and accuracy during the linear motion, friction models of LM ball guides are required. To formulate accurate frictional models of LM ball guides according to load and preload conditions, rolling and viscous frictional analyses have been performed in this paper. Contact loads between balls and grooves are derived from Hertzian contact analysis. Contact angle variation is incorporated for the precision modeling. Viscous friction model is formulated from the shear stress of lubricant and the contact area between balls and grooves. Experiments confirm validity of the developed friction model for various external load and feedrate conditions.