• The Korean Journal of Physiology and Pharmacology
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• 제16권4호
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• pp.265-271
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• 2012

HoxB4, a homeodomain-containing transcription factor, is involved in the expansion of hematopoietic stem cells and progenitor cells in vivo and in vitro, and plays a key role in regulating the balance between hematopoietic stem cell renewal and cell differentiation. However, the biological activity of HoxB4 in other cells has not been reported. In this study, we investigated the effect of overexpressed HoxB4 on cell survival under various conditions that induce death, using the Ba/F3 cell line. Analysis of phenotypical characteristics showed that HoxB4 overexpression in Ba/F3 cells reduced cell size, death, and proliferation rate. Moreover, the progression from early to late apoptotic stages was inhibited in Ba/F3 cells subjected to HoxB4 overexpression under removal of interleukin-3-mediated signal, leading to the induction of cell cycle arrest at the G2/M phase and attenuated cell death by Fas protein stimulation in vitro. Furthermore, apoptotic cell death induced by doxorubicin-treated G2/M phase cell-cycle arrest also decreased with HoxB4 overexpression in Ba/F3 cells. From these data, we suggest that HoxB4 may play an important role in the regulation of pro-B cell survival under various apoptotic death environments.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.223-230
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• 2019

A facile method for surface coating with $Li_2TiF_6$ which has a high lithium-ion conductivity, on $LiMn_2O_4$ spinel cathode material for high performance lithium ion batteries. The surface coating is performed by using a co-precipitation method with $Li_2CO_3$ powder and $H_2TiF_6$ solution under room temperature and atmospheric pressure without special equipment. Total coating amount of $Li_2TiF_6$ is carefully controlled from 0 to 10 wt.% based on the active material of $LiMn_2O_4$. They are evaluated by a systematic combination of analyses comprising with XRD, SEM, TEM and ICP. It is found that the surface modification of $Li_2TiF_6$ is very beneficial to high cycle life and excellent rate capability by reducing surface failure and supporting lithium ions transportation on the surface. The best coating condition is found to have a high cycle life of $103mAh\;g^{-1}$ at the 100th cycle and a rate capability of $102.9mAh\;g^{-1}$ under 20 C. The detail electrochemical behaviors are investigated by AC impedance and galvanostatic charge and discharge test.

• 한국수소및신에너지학회논문집
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• 제33권2호
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• pp.148-157
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• 2022

Research on hydrogen storage is active to properly deal with hydrogen, which is considered a next-generation energy medium. In particular, research on metal hydride with excellent safety and energy efficiency has attracted attention, and among them, magnesium-based hydrogen storage alloys have been studied for a long time due to their high storage density, low cost, and abundance. However, Mg-based alloys require high temperature conditions due to strong binding enthalpy, and have many difficulties due to slow hydrogenation kinetics and reduction in hydrogen storage capacity due to oxidation, and various strategies have been proposed for this. This research manufactured Mg₂Ni to improve hydrogenation kinetics and synthesize about 5, 10, 20 wt% of CaF₂ as a catalyst for controlling oxidation. Mg₂NiHx-CaF₂ produced by hydrogen induced mechanical alloying analyzed hydrogenation kinetics through an automatic PCT measurement system under conditions of 423 K, 523 K, and 623 K. In addition, material life cycle assessment was conducted through Gabi software and CML 2001 and Eco-Indicator 99' methodology, and the environmental impact characteristics of the manufacturing process of the composites were analyzed. In conclusion, it was found that the effects of resource depletion (ARD) and fossil fuels had a higher burden than other impact categories.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.104-104
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• 2001

Purpose： In this study, we investigated the possible motor pathways of hemiplegic stroke patients usin combined TMS and BOLD fMRI approach and evaluated the correlation between TMS a fMRI methods. Method： Four subjects, who demonstrated left hemiplegia after stroke, are included. TMS was performed using a Dantec Mag2 stimulator (Dantec Company, USA) in single puls mode with figure eight-shaped coil. Following TMS localization, The BOLD T2＊-weight images were acquired with echo planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = 90). Motor activation was studied by means of a repetitive fing flexion-extension task. The stimulation protocol comprised 10 cycles of alternating activati and rest (10 images per cycle). Total 60 cycles were performed and each cycle take abou 1.5 sec. The resulting images were then analyzed with STIMULATE (CMRR, U, o Minnesota) to generate functional maps using a student t-test (p < 0.0005) and cluste analysis.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.14-21
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• 2001

To estimate crack growth rate and cycle ratio uniquely, many investigators have developed various kinds of mechanical parameters and theories. But, thes have produced local solution space through single parameter. Neural Networks can perform patten classification using several input and output parameters. Fatigue damage model by neural networks was used to recognize the relation between da/dN/N/N(sub)f, and half-value breadth ratio B/Bo, fractal dimension D(sub)f, and fracture mechanical parameters in 2024-T3 aluminium alloy. Learned neural networks has ability to predict both crack growth rate da/dN and cycly ratio /N/N(sub)f within engineering estimated mean error(5%).

• 설비공학논문집
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• 제23권7호
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• pp.513-519
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• 2011

The object of this study is to investigate the performance characteristics of refrigerators using a single-circuit multi cycle and a bypass two-circuit multi cycle. Each refrigeration cycle was tested by varying secondary fluid mass flow rate and temperature. Based on the experimental data, the optimum refrigerant charge was 48 g and the COP at the optimum secondary fluid mass flow rate was 1.53 for the single-circuit multi cycle. For freezer(F)-only mode, both the single-circuit multi cycle and the bypass two-circuit multi cycle were operated at overcharge conditions, resulting in an increase of the secondary fluid mass flow rate. The maximum COPs of the single-circuit multi cycle and the bypass two-circuit multi cycle were 1.22 and 1.35, respectively. The COP increased by 10.7% with the application of the bypass two-circuit multi cycle.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.206-207
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• 1989

• 대한기계학회논문집
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• 제9권5호
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• pp.539-547
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• 1985

본 논문에서는 이상과 같은 연구현상을 배경으로 응력비 R.geq.0인 사인응력파 에서도 사이클의존형 크랙전파가 공존하는가, 공존한다면 그 전이를 결정짓는 조건을 구하기 위해, 대표적인 고온용 재료인 SUS 304강을 이용하여 온도 650.deg. C, 대기중에서 반복속도 .nu., 응력비 R, 응력레벨 .sigma.$_{maxo}$등의 실험조건을 바꾸어 고온저사이클 피로실험을 하였다. 또 이 현상의 기초과정을 이해하는데 도움을 주기 위하여 파면 관찰을 행하였다.

• 한국자동차공학회논문집
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• 제24권4호
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• pp.454-462
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• 2016

This study was conducted in order to estimate the exhaust emissions analysis method of the real driving emission(RDE). The Association for Emissions Control by Catalyst(AECC) has developed a test procedure by using a random cycle method based on the chassis dynamometer. In order to confirm this approach in Korea, Euro 5(DPF), Euro 6(DPF + LNT), and Euro 6(DPF + SCR) were performed on three different vehicles to determine the exhaust gas characteristics of the random cycle, real-road driving test(PEMS), and emission certification driving mode(NEDC). Six different random cycle driving modes were generated by the vehicle specifications(e.g. curb weight, engine power, gear ratio, and maximum acceleration). The NOx emissions were increased in the NEDC, random cycle, and PEMS order in this study regardless of the test vehicles. The random cycle method has the advantage because it utilizes a chassis dynamometer in the laboratories for a repeatable data collection, and it allows any eminent emission improvement checked prior to a real-road driving test with PEMS.

• 대한치과보철학회지
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• 제59권4호
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• pp.379-394
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• 2021

목적: 이전 연구에서 치은섬유아세포 혹은 성견 구개 연조직에 trichloroacetic acid (TCA)를 적용하는 것이 세포주기진행 유전자 발현의 변화를 일으키는 것으로 밝혀졌다. 이에 따라 본 연구에서는, hydrophobically modified glycol chitosan (HGC)기반의 나노방출제어시스템을 이용한 TCA 및 상피세포성장인자(EGF)의 순차적 방출시스템에서 이 효과를 검증하기 위하여 다양한 세포주기진행 유전자들의 발현을 규명하였다. 재료 및 방법: TCA와 EGF를 담지하는 HGC기반 나노방출제어시스템을 제작하였다. 실험군은 대조군(CON); TCA-담지형 나노방출제어시스템 투여군(EXP1); TCA- 및 EGF-담지형 나노방출제어시스템 투여군(EXP2)으로 정의되었다. 24시간 및 48시간 배양 시 37개 세포주기 유전자들의 발현을 분석하였다. 영향인자로서의 유전자 및 상관관계에 대해서도 분석하였다. 결과: Cyclins (CCNDs), cell division cycles (CDCs), cyclin-dependent kinases (CDKs), E2F transcription factors (E2Fs), extracellular signal-regulated kinases (ERKs)와 같은 다수의 유전자들과 기타 다른 세포주기 유전자들의 발현이 EXP1과 EXP2에서 상향조절되었다. E2F4, E2F5, GADD45G와 같은 세포주기차단 유전자들의 발현도 상향조절되었으나, 또다른 세포주기차단 유전자인 SMAD4의 발현은 하향조절되었다. 다중회귀분석에서 CCNA2, CDK4 그리고 ANAPC4가 ERK 유전자 발현에 가장 영향력 있는 유전자로 선정되었다. 결론: HGC기반 순차적 나노방출제어시스템을 이용한 TCA 및 EGF의 적용은 다양한 세포주기진행 유전자들의 발현을 상향조절함이 밝혀졌고, 이를 토대로 한 구강연조직증대시스템 개발의 가능성이 확보되었다.