• JSTS:Journal of Semiconductor Technology and Science
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• 제8권2호
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• pp.139-142
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• 2008

An X-band MMIC power amplifier for radar application is developed using $0.25-{\mu}m$ gate length GaAs pHEMT technology. A bus-bar power combiner at output stage is used to minimize the combiner size and to simplify bias network. The fabricated power amplifier shows 38.75 dBm (7.5 Watt) Psat at 10 GHz. The chip size is $3.5\;mm{\times}3.9\;mm$.

• 한국전자파학회논문지
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• 제24권11호
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• pp.1064-1073
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• 2013

본 논문에서는 내부 고조파 조정 회로로 구성되는 셀룰러와 L-대역용 소형의 고효율 370 W GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) 소형 전력 증폭기(PA)를 구현하였다. 원천 및 2차 고조파 주파수에서 동시에 높은 효율을 내기 위해 새로운 회로 정합 형태를 적용했다. 소형화를 위하여 새로운 41.8 mm GaN HEMT와 2개의 MOS(Metal Oxide Semiconductor) 캐패시터를 구성 물질의 변화를 이용하여 열 저항을 개선한 $10.16{\times}10.16{\times}1.5Tmm^3$ 크기의 새로운 패키지에 와이어 본딩으로 결합하였다. 드레인 바이어스 48 V 인가 시, 개발된 GaN HEMT 전력 증폭기는 370 W 포화 출력 전력(Psat.)과 770~870 MHz에서 80 % 이상, 1,805~1,880 MHz에서 75 % 이상의 드레인 효율(DE)을 나타내었다. 이는 지금까지 보고된 셀룰러와 L대역에서 GaN HEMT 전력 증폭기 중 최고의 효율과 출력 전력 특성이다.

• 생명과학회지
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• 제26권12호
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• pp.1367-1375
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• 2016

Cilostazol은 phosphodiesterase III의 선택적 저해제로 알려져 있으며, 뇌졸중 치료에 일반적으로 사용되고 있다. Cilostazol을 처리한 경우, 국소 뇌허혈이 발생한 후에 혈관신생을 통해서 혈관형성이 향상된다는 것을 본 연구자들이 발표하였다. 혈관신생은 조직의 허혈상태를 극복하기 위해서 혈관재생을 촉진하는 중요한 과정으로써, 혈관내피세포의 증식, 이동, 모세관구조 형성의 다단계 과정으로 구성되어 있다. 이에 본 연구에서는 인간 뇌혈관내피세포를 이용하여 cilostazol이 혈관신생의 각 단계들에 어떤 영향을 미치는지 조사하였다. Cilostazol은 농도의존적으로 뇌혈관내피세포의 이동성을 촉진하였으나, 뇌혈관내피세포의 증식과 모세관구조 형성에는 영향을 미치지 않았다. Cilostazol이 세포이동을 조절하는 기전을 분석하기 위해서 cDNA microarray를 수행하였고, 세포이동에 관련성이 있는 5종의 후보 유전자들을 선택하여 real-time PCR을 통해 해당 유전자의 발현을 검증하였다. Cilostazol에 의해서 발현양이 조절되는 유전자들로써, phosphoserine aminotransferase 1 (PSAT1)와 CCAAT/enhancer binding protein ${\beta}$ ($C/EBP{\beta}$)은 발현이 증가하였고, tissue factor pathway inhibitor 2 (TFPI2), retinoic acid receptor responder 1 (RARRES1), RARRES3는 발현이 감소하였다. 이상의 결과를 통해서 cilostazol이 혈관내피세포의 이동을 촉진하여 혈관신생을 향상시킬 수 있음을 제안할 수 있으며, 뇌혈관내피세포에 대한 cilostazol의 조절기전에 대해서 더욱 상세히 규명을 한다면 혈관형성을 통하여 허혈성 질환을 치료할 수 있는 유용한 정보가 될 것으로 기대한다.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1431-1438
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• 2013

A pack-level battery hardware-in-the-loop simulation (B-HILS) platform is implemented. It consists of dynamic vehicle models using PSAT and multiple control interfaces including real-time 3D driving and GPS mode. In real-time 3D driving mode, user can drive a virtual vehicle using actual drive equipment such as steering wheel and accelerator to generate the cycle profile of the battery. In GPS mode, actual road traffic and terrain effects can be simulated using GPS data while the trajectory is displayed on Google map. In the latter part of the paper, several performance tests of an actual lithium-polymer battery pack are carried out utilizing the developed system. All experiments are conducted as parts of actual development process of a commercial battery pack adopting 2nd generation Prius as a target vehicle model. Through the experiments, the low temperature performance and fuel efficiency of the battery are quantitatively investigated in comparison with the original nickel-metal hydride (NiMH) pack of the Prius.

• Fisheries and Aquatic Sciences
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• 제27권2호
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• pp.76-86
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• 2024

The bio-logging method could be a valuable approach to studying the underwater movement of marine fish. We investigated the horizontal and vertical movement patterns of two yellowtails Seriola quinqueradiata weighing 8.7 kg and 9.5 kg with a popup satellite archival tag from October 2020 to January 2021 in the East Sea of Korea. Our results showed that a yellowtail migrated northward in October and November, and then shifted southward in mid-December. The average swimming depth and temperature of the fish monitored over 82 days were 24.9 ± 9.3 m (average ± SD) and 16.5 ± 1.9℃, respectively, and the total traveled distance was 1,172.4 km. The fish swam significantly deeper during the daytime (33.70 ± 14.80 m) than at nighttime (20.65 ± 8.44 m) from November to December (p < 0.05). These results suggest that the horizontal migratory route of yellowtails in accordance with the East Korea Warm Current which is the main branch of Tsushima Warm Current in the fall and early winter seasons, and showed significant diel vertical movement patterns from November to December.

• Journal of Periodontal and Implant Science
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• 제41권1호
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• pp.30-43
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• 2011

Purpose: Under different culture conditions, periodontal ligament (PDL) stem cells are capable of differentiating into cementoblast-like cells, adipocytes, and collagen-forming cells. Several previous studies reported that because of the stem cells in the PDL, the PDL have a regenerative capacity which, when appropriately triggered, participates in restoring connective tissues and mineralized tissues. Therefore, this study analyzed the genes involved in mineralization during differentiation of human PDL (hPDL) cells, and searched for candidate genes possibly associated with the mineralization of hPDL cells. Methods: To analyze the gene expression pattern of hPDL cells during differentiation, the hPDL cells were cultured in two conditions, with or without osteogenic cocktails (${\beta}$-glycerophosphate, ascorbic acid and dexamethasone), and a DNA microarray analysis of the cells cultured on days 7 and 14 was performed. Reverse transcription-polymerase chain reaction was performed to validate the DNA microarray data. Results: The up-regulated genes on day 7 by hPDL cells cultured in osteogenic medium were thought to be associated with calcium/iron/metal ion binding or homeostasis (PDE1A, HFE and PCDH9) and cell viability (PCDH9), and the down-regulated genes were thought to be associated with proliferation (PHGDH and PSAT1). Also, the up-regulated genes on day 14 by hPDL cells cultured in osteogenic medium were thought to be associated with apoptosis, angiogenesis (ANGPTL4 and FOXO1A), and adipogenesis (ANGPTL4 and SEC14L2), and the down-regulated genes were thought to be associated with cell migration (SLC16A4). Conclusions: This study suggests that when appropriately triggered, the stem cells in the hPDL differentiate into osteoblasts/cementoblasts, and the genes related to calcium binding (PDE1A and PCDH9), which were strongly expressed at the stage of matrix maturation, may be associated with differentiation of the hPDL cells into osteoblasts/cementoblasts.

• 대한골대사학회지
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• 제25권4호
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• pp.251-266
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• 2018

Background: The causal networks among genes that are commonly expressed in osteoblasts and during bone metastasis (BM) of breast cancer (BC) are not well understood. Here, we developed a machine learning method to obtain a plausible causal network of genes that are commonly expressed during BM and in osteoblasts in BC. Methods: We selected BC genes that are commonly expressed during BM and in osteoblasts from the Gene Expression Omnibus database. Bayesian Network Inference with Java Objects (Banjo) was used to obtain the Bayesian network. Genes registered as BC related genes were included as candidate genes in the implementation of Banjo. Next, we obtained the Bayesian structure and assessed the prediction rate for BM, conditional independence among nodes, and causality among nodes. Furthermore, we reported the maximum relative risks (RRs) of combined gene expression of the genes in the model. Results: We mechanistically identified 33 significantly related and plausibly involved genes in the development of BC BM. Further model evaluations showed that 16 genes were enough for a model to be statistically significant in terms of maximum likelihood of the causal Bayesian networks (CBNs) and for correct prediction of BM of BC. Maximum RRs of combined gene expression patterns showed that the expression levels of UBIAD1, HEBP1, BTNL8, TSPO, PSAT1, and ZFP36L2 significantly affected development of BM from BC. Conclusions: The CBN structure can be used as a reasonable inference network for accurately predicting BM in BC.