• 한국정보통신학회논문지
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• 제11권8호
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• pp.1574-1581
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• 2007

휴대용 디지털 방송 표준으로 추진되고 있는 DVB-H는 유럽 지상파 디지털 방송시스템 표준인 DVB-T 전송망으로 휴대용 수신기에 다양한 멀티미디어데이터를 전송하기 위하여 추가, 보완한 기술규격으로, 휴대형 단말기에서의 방송 수신을 목표로 하고 있다. 이러한 DVB-H시스템은 단말의 이동성과 전력효율성을 중요한 특징으로 하고 있다. 따라서 이동중인 수신기가 다중 주파수 망(MFN)으로 구성된 방송망에서 서로 다른 주파수망으로 이동할 경우 끊김 없는 주파수 핸드오버가 이루어져야 한다. 이때 핸드오버를 위해 인접 주파수들을 검색해야하는데 이 경우 휴대단말에 큰 전력소모를 야기한다. 따라서 보다 전력효율적인 핸드오버를 위한 셀 탐색 기법이 요구된다. 본 논문에서는 보다 빠른 주파수 검색을 통해 전력효율을 증가시킨 Hypothesis 테스팅기반의 핸드오버 방식을 제안하고 그 성능을 비교 분석하였다.

• 한국발생생물학회지:발생과생식
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• 제26권2호
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• pp.71-77
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• 2022

In response to luteinizing hormone (LH), a higher concentration of progesterone (P4) is produced in luteal cells of corpus luteum (CL). Mitochondria are an essential cellular organelle in steroidogenesis. The specific engagement of the concept regarding mitochondrial shaping with early stages of steroidogenesis was suggested in reproductive endocrine cells. Although the specific involvement of GTPase dynamin-related protein 1 (Drp1) with steroidogenesis has been demonstrated in luteal cells of bovine CL in vitro, its actual relationship with ovarian steroidogenesis during the estrous cycle remains unknown. In this study, while Fis1 and Opa1 protein levels did not show significant changes during the estrous cycle, Drp1, Mfn1, and Mfn2 proteins exhibited relatively lower levels at proestrus than at estrus or diestrus. 3β-HSD showed higher levels at proestrus than at estrus or diestrus. In addition, Drp1 phosphorylation (s637) was higher in proestrus than in estrus or diestrus. Immune-positive cells for Drp1, pDrp1 (s637), and 3β-HSD were all localized in the cytoplasm of luteal cells in the CL. The immune-positive cells for 3β-HSD were more frequently seen in the CL at proestrus than at estrus or diestrus. Immunoreactivity for Drp1 in luteal cells at proestrus was weaker than that at estrus or diestrus. However, pDrp1 (s637) immune-positive cells were mostly detected in luteal cells at proestrus. These results imply that steroidogenesis (P4 production) in the CL is closely related to phosphorylation of Drp1 at serine 637. Taken together, this study presents evidence that Drp1 phosphorylation at serine 637 is an important step in steroidogenesis in the CL.

• Nutrition Research and Practice
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• 제16권2호
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• pp.147-160
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• 2022

BACKGROUND/OBJECTIVES: Patients with chronic kidney disease (CKD) have a high concentration of uremic toxins in their blood and often experience muscle atrophy. Indoxyl sulfate (IS) is a uremic toxin produced by tryptophan metabolism. Although an elevated IS level may induce muscle dysfunction, the effect of IS on physiological concentration has not been elucidated. Additionally, the effects of ursolic acid (UA) on muscle hypertrophy have been reported in healthy models; however, it is unclear whether UA ameliorates muscle dysfunction associated with chronic diseases, such as CKD. Thus, this study aimed to investigate whether UA can improve the IS-induced impairment of mitochondrial biogenesis. MATERIALS/METHODS: C2C12 cells were incubated with or without IS (0.1 mM) and UA (1 or 2 μM) to elucidate the physiological effect of UA on CKD-related mitochondrial dysfunction and its related mechanisms using real-time reverse transcription-polymerase chain reaction, western blotting and enzyme-linked immunosorbent assay. RESULTS: IS suppressed the expression of differentiation marker genes without decreasing cell viability. IS decreased the mitochondrial DNA copy number and ATP levels by downregulating the genes pertaining to mitochondrial biogenesis (Ppargc1a, Nrf1, Tfam, Sirt1, and Mef2c), fusion (Mfn1 and Mfn2), oxidative phosphorylation (Cycs and Atp5b), and fatty acid oxidation (Pdk4, Acadm, Cpt1b, and Cd36). Furthermore, IS increased the intracellular mRNA and secretory protein levels of interleukin (IL)-6. Finally, UA ameliorated the IS-induced impairment in C2C12 cells. CONCLUSIONS: Our results indicated that UA improves the IS-induced impairment of mitochondrial biogenesis by affecting differentiation, ATP levels, and IL-6 secretion in C2C12 cells. Therefore, UA could be a novel therapeutic agent for CKD-induced muscle dysfunction.

• Molecules and Cells
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• 제43권10호
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• pp.880-888
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• 2020

Inherited peripheral neuropathy is a heterogeneous group of peripheral neurodegenerative disorders including Charcot-Marie-Tooth disease. Many peripheral neuropathies often accompany impaired axonal construction and function. To study the molecular and cellular basis of axon-defective peripheral neuropathy, we explore the possibility of using Caenorhabditis elegans, a powerful nematode model equipped with a variety of genetics and imaging tools. In search of potential candidates of C. elegans peripheral neuropathy models, we monitored the movement and the body posture patterns of 26 C. elegans strains with disruption of genes associated with various peripheral neuropathies and compiled a database of their phenotypes. Our assay showed that movement features of the worms with mutations in HSPB1, MFN2, DYNC1H1, and KIF1B human homologues are significantly different from the control strain, suggesting they are viable candidates for C. elegans peripheral neuropathy models.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 하계학술대회
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• pp.398-400
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• 2013

2012년 말 아날로그 TV의 종료와 함께 기존의 아날로그 TV에서 사용하고 있는 채널들이 유휴 대역으로 존재한다. 현재 비교적 많은 유휴 상태로 있는 대역을 효율적으로 사용하기 위한 논의가 지속적으로 진행 중이다. 본 논문에서는 차세대 방송서비스를 위한 주파수 재분배 방법에 대해서 분석하였다. 차세대 방송 서비스는 역호환성(Backward Compatibility)이 보장되어야 한다고 가정하고, 현재 구성 되어있는 다중 주파수 망(MFN : Multi Frequency Network)의 한계와 이를 극복할 수 있는 방법에 대해서 기술하였다. 단일 주파수 망(SFN : Single Frequency Network)의 구성이 가능 한 경우, 현재 서비스 중인 HDTV 방송 서비스와 차후 제공할 수 있는 차세대 방송 서비스를 동시에 제공할 수 있도록 주파수 분배 안을 제시하였다.

• 한국중재학회지:중재연구
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• 제23권3호
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• pp.127-147
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• 2013

Korea is, after China, the Asian country with the largest number of concluded investment treaties. One of the protections that Korean investment treaties frequently afford to foreign investors and their investment is the so-called "umbrella clause," which requires the host state of the investment to observe the commitments that it has undertaken toward the foreign investor or its investment. This is a potentially very powerful protection. Umbrella clauses, however, have proven to be amongst the most controversial provisions in investment treaties, giving rise to diverging interpretations by tribunals and commentators that are still not reconciled today.

• 한국콘텐츠학회논문지
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• 제13권12호
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• pp.702-714
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• 2013

한중일은 새로운 경제성장을 위한 고민과 더불어 외자를 유치함에 있어 새로운 도전과 어려움에 직면해 있다. 향후 한중일 FTA는 3국간의 투자를 더욱 촉진 할 것으로 기대되고 있다. 이 논문은 한중일 3국간의 투자에 관한 법적체계와 제약요소 및 투자규칙에 관한 연구를 하였다. 3국간의 무역경제 관계와 투자흐름을 검토하고, 이를 배경으로 3국의 외국투자에 관한 법적체계 및 투자규칙에 관한 검토를 통하여 상대국에 있어서 투자에 관한 주요한 제약이 무엇인지, 향후 한중일 FTA는 3국간의 투자를 더욱 촉진하기 위해서는 한중일 FTA 투자 장(章)에 포함해야 할 것이 무엇인지를 제시하고자 하였다. 한중일 FTA는 3방향의 투자 흐름을 원활화하고 3국간에 투자자와 투자보호를 강화하기위한 효과적인 수단이 될 것이다. 이 점에서 향후 한중일 FTA 투자 장은 내국민 대우, 최혜국대우, 특정조치의 이행요구의 금지 및 경영진이나 이사회의 국적 요건, 자금의 이전, 세이프가드 조치, 수용 및 보상, 손실에 대한 보상, 공정 형평 대우, 투자자 대 국가의 분쟁 해결 및 3국 간 합의 된 다른 요소를 포함해야한다.

• Molecules and Cells
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• 제42권12호
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• pp.893-905
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• 2019

Mitochondria are highly dynamic organelles that constantly undergo fission and fusion processes that closely related to their function. Disruption of mitochondrial dynamics has been demonstrated in acute kidney injury (AKI), which could eventually result in cell injury and death. Previously, we reported that augmenter of liver regeneration (ALR) alleviates renal tubular epithelial cell injury. Here, we gained further insights into whether the renoprotective roles of ALR are associated with mitochondrial dynamics. Changes in mitochondrial dynamics were examined in experimental models of renal ischemia-reperfusion (IR). In a model of hypoxia-reoxygenation (HR) injury in vitro, dynamin-related protein 1 (Drp1) and mitochondrial fission process protein 1 (MTFP1), two key proteins of mitochondrial fission, were downregulated in the Lv-ALR + HR group. ALR overexpression additionally had an impact on phosphorylation of Drp1 Ser637 during AKI. The inner membrane fusion protein, Optic Atrophy 1 (OPA1), was significantly increased whereas levels of outer membrane fusion proteins Mitofusin-1 and -2 (Mfn1, Mfn2) were not affected in the Lv-ALR + HR group, compared with the control group. Furthermore, the mTOR/4E-BP1 signaling pathway was highly activated in the Lv-ALR + HR group. ALR overexpression led to suppression of HR-induced apoptosis. Our collective findings indicate that ALR gene transfection alleviates mitochondrial injury, possibly through inhibiting fission and promoting fusion of the mitochondrial inner membrane, both of which contribute to reduction of HK-2 cell apoptosis. Additionally, fission processes are potentially mediated by promoting tubular cell survival through activating the mTOR/4E-BP1 signaling pathway.

• 한국인터넷방송통신학회논문지
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• 제9권6호
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• pp.9-14
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• 2009

본 논문에서는 단일 주파수 망을 이용하는 AT-DMB 시스템에서의 효율적인 송신기 검출을 위한 확산코드 슬라이싱 기술을 제안하였다. 각 송신 단말기 신호에 상관특성이 좋은 고유의 확산코드를 AT-DMB 프레임의 Null 심벌의 일부에 나누어 할당하고, 수신기에서는 송신 단말기의 고유 코드를 이용하여 다른 단말기의 신호 간섭 상황 하에서도 원하는 신호를 검출하여 수신할 수 있게 한다. 제안된 기법에 의해 얻어진 송신기 정보는 주파수를 효율적으로 사용하기 위한 기술인 SFN 구현을 위해 필요하다. 본 논문의 결과는 무선 디지털 방송 통신 시스템 구현에 적용될 수 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.54-57
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• 2002

In this study, a new programming method, to minimize the generation of Si-SiO$_2$ interface traps of scaled SONOS flash memory as a function of number of program/erase cycles has been proposed. In the proposed programming method, power supply voltage is applied to the gate, forward biased program voltage is applied to the source and the drain, while the substrate is left open, so that the program is achieved by Modified Fowler-Nordheim (MFN) tunneling of electron through the tunnel oxide over source and drain region. For the channel erase, erase voltage is applied to the gate, power supply voltage is applied to the substrate, and the source and drain are open. A single power supply operation of 3 V and a high endurance of 1${\times}$10$\^$6/ prograss/erase cycles can be realized by the proposed programming method. The asymmetric mode in which the program voltage is higher than the erase voltage, is more efficient than symmetric mode in order to minimize the degradation characteristics of scaled SONOS devices because electrical stress applied to the Si-SiO$_2$ interface is reduced by short programming time.