• BMB Reports
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• v.29 no.3
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• pp.205-209
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• 1996

To investigate the role of heparin in keratinocyte growth factor (KGF) and acidic fibroblast growth factor (aFGF) high affinity binding to the KGF receptor (KGFR), a cell free system was established which utilized a secreted chimeric molecule between the KGFR extracellular domain and the immunoglobulin heavy chain Fc domain (KGFR-HFc). KGFR-HFc was purified from NIH 3T3 cells and demonstrated the binding of $[^3H]-heparin$ as well as heparin Sepharose. Scatchard analysis showed that the dissociation constant for heparin binding to KGFR-HFc was 140 nM. High affinity KGF and aFGF binding to KGFR-HFc remained unchanged after treatment with 0.6 M NaCl, which is the concentration sufficient to release any bound heparin to the KGFR-HFc. These results strongly suggest that although the KGFR interacts with heparin, the presence of heparin is not absolutely required for high affinity binding of either KGF or aFGF to the KGFR.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.51-64
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• 1994

Analytical study on the thermodynamical cyclic behabiour and characteristics of HFC-l34a refrigerant for automotive air conditionser system for the replacement of existing CFC-12 has been carried out in this paper through development of system performance simulation program, expecially in the view point of system design considerations. The results indicate that HFC-l34a system will give a greater refrigerating capacity than CFC-12 if appropriate engineering measures such as proper codensers, flow controllers, etc., taken for certain operating conditions. The results, however, also show that the operating power for compression process increases over entire temperature range as a result of decreasing volumetric efficiency due to larger specific volume and increased discharging pressure. The present study results indicate that proper selection of condensing and evaporating temperature plus refrigerant control is very important performance factor to have better COP in the HFC-134a system design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.4
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• pp.262-270
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• 2001

This paper deals with a prediction method for the condensation of ternary refrigerant mixture inside a horizontal smooth tube. Based on some reliable assumptions, the governing equations for the local heat and mass transfer characteristics are derived, and the prediction for the condensation of ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a, including R407C, is carried out. The local values of vapor quality, thermodynamic states at bulk vapor, vapor-liquid interface and bulk liquid, mass flux etc. are obtained for a constant wall temperature and a constant wall heat flux conditions, and the effects of the composition of HFC32/HFC125/HFC134a on heat transfer characteristics are examined. The prediction result is also compared with experimental data for condensation of ternary refrigerant mixtures. The predicted wall temperature distribution has a similar trend with experimental data but the predicted local heat transfer coefficients are 20-30% higher than the experimental data.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.369-369
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• 2000

Control system by means of fuzzy theory has demonstrated its robustness in applying to the high-order and nonlinear dynamic system in that it can utilizes the human expert knowledges in system design. In this paper, first, the design methodology of HFC combined PID controller with fuzzy controller by membership function of weighting coefficient is proposed. Second, Second, an auto-tuning algorithms utilizing the simplified reasoning method and genetic algorithms is presented to improve the performance of hybrid fuzzy controller. Especially, in order to obtain the optimal scaling factors and PID parameters of HFC using GA based on advanced initial individual, three kinds of estimation modes such as basic, contraction, and expansion mode are effectively utilized. The proposed HFC is evaluated and discussed in ITAE, overshoot and rising time to show applicability and superiority with simulation results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.468-476
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• 2002

This paper deals with heat and mass transfer characteristics and performance evaluation of a counter flow double-tube condenser for a multi-component refrigerant mixture. The local heat and mass transfer characteristics of ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a are evaluated for a counter flow double-tube condenser cooled by water. Then, the local values of vapor quality, thermodynamic states at bulk vapor, vapor-liquid interface and bulk liquid, heat flux and condensation mass flux are obtained. The heat exchange performance for ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a on the total pressure drop and the heat transfer characteristics are also compared with those for R404A, R410A, R502, R22, R32, Rl23 and R134a.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.191-194
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• 2010

본 논문에서는 HFC 망에서 상향 대역의 잡음신호를 중심으로, 잡음신호 및 스펙트럼을 분석하여 HFC 전송망의 효율적 장애처리 방안을 제시한다. HFC망은 빠른 속도로 다양한 멀티미디어 서비스를 제공하는 장점에도 불구하고 동축 구간이 외부의 환경적 영향을 많이 받을 가능성과 상향 잡음의 유입으로 디지털 전송망에 비교하여 상대적으로 어려움이 있다. 따라서 본 연구는 유입잡음을 스펙트럼 분석하여 유형화함으로서 잡음신호의 원인에 따른 신속한 대처와 인적, 물적 자원 투입요소 최소화가 기대된다.

• Electronics and Telecommunications Trends
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• v.18 no.6 s.84
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• pp.34-40
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• 2003

1998년 시작된 초고속 인터넷 서비스는 약 4년 만에 세계 1위의 보급률을 보이고 있을 정도로 우리 나라의 정보통신 인프라는 급속도로 성장하여 왔다. 최근 유무선 통합 및 통신과 방송이 융합되는 광대역 통합망(BcN) 환경에서 초고속 인터넷 서비스와 디지털방송 서비스를 제공하기 위한 초고속 인프라의 가입자망 형태는 동선 기반의 ADSL(Asymmetric Digital Subscriber Line)/VDSL(Very high-data rate Digital Subscriber Line) 및 광/동축 혼합망인 HFC, 광섬유 기반의 FTTH(Fiber To The Home) 등이 있다. 그 중에서 HFC는 그 동안 주로 케이블 TV 프로그램의 전송망으로 활용되어 오다가 최근 통신. 방송 융합 환경에서 초고속 인터넷 가입자망으로 부각되고 있다. 본 고에서는 HFC 망의 특성과 HFC 망의 핵심장비인 CMTS와 케이블모뎀의 시장 현황 및 전망에 대해서 알아보고, 광대역 통합망의 가입자망으로서의 HFC의 역할에 대해 논의하고자 한다.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.518-526
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• 2012

The objective of this research was to develop fugitive emission models of HFC-134a (Hydrofluorocarbon-134a) at the operation and disposal stages of passenger cars. It is essential to estimate the emission of HFC-134a from mobile air conditioner (MAC) due to its high Global Warming Potential (GWP) and extensive use as a refrigerant in MAC. The first-order emission model was introduced and the emission rate constant was assumed to be unvaried with time. A commercial recovery station of refrigerants was used to recover the HFC-134a from the MAC. Average emission rate constant and annual emission rate during the operation period of vehicle are estimated to be $0.0538{\pm}0.0092$ (n=21) $yr^{-1}$ and $5.2{\pm}0.6%$, respectively within a confidence interval of 95%. According to the model results, about 50% of HFC-134a would be emitted from the MAC during the 10 years operation of passenger cars. On the other hand, average remaining portion of HFC-134a in the MACs of scrap cars is $58.2{\pm}4.8%$ (n=50) within a confidence interval of 95%, suggesting that over 40% of the initially charged amount could be released fugitively after disposal provided that the HFC-134a would not be properly treated or recycled.

• Mycobiology
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• v.46 no.2
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• pp.159-167
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• 2018

This study evaluated the in vitro and in vivo hypolipidemic effects of the medicinal mushroom Phellinus pini. The methanol extract (ME) of the fruiting body of Ph. pini was active against pancreatic lipase and cholesterol esterase with 99.14% and 67.23% inhibited activity at 1.0 mg/mL, respectively. It also inhibited 81.81% and 55.33% of ${\alpha}$-glucosidase and ${\alpha}$-amylase activities, respectively, at 2.0 mg/mL. Hyperlipidemia as induced by feeding rats with a high fat and cholesterol diet (HFC). HFC supplemented with a 5% fruiting body powder of Ph. pini (HFC + PhP) significantly reduced plasma total cholesterol, low-density lipoprotein cholesterol, and triglycerides in rats compared with HFC. The reduced levels were comparable to rats fed the normal control diet (NC). The atherogenic index of HFC + PhP rats was significantly lower than that of the HFC rats. The excretion of fecal total lipid and cholesterol in the HFC + PhP rats was significantly higher than those in the NC and HFC rats. Histopathological examinations demonstrated scant deposition of lipids in the liver of rats fed HFC + PhP. The dietary supplementation with the fruiting body powder provided natural plasma lipid and glucose lowering effects in experimental rats without adverse effects on the plasma biochemical parameters and liver function related enzyme activities. Therefore, the hypolipidemic effects of Ph. pini may be due to the inhibitory effects on pancreatic lipase, cholesterol esterase, ${\alpha}$-glucosidase, and ${\alpha}$-amylase, and excretion of excess lipids and cholesterol in the feces.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.113-118
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• 2017

As interest in mobile devices and networks has increased recently, voice over internet protocol (VoIP) service, which is a technology for transmitting voice data using an existing internet protocol (IP) network, has rapidly spread, Cheap voice call service has become possible. As the digital broadcasting service becomes popular, hybrid fiber coaxial (HFC) network technology, which uses broadband cable network through fusion of broadcasting and communication, utilizes existing communication system and network equipment to provide various new services such as interactive broadcasting service. Therefore, if UGS-AD is applied to VoCM and RTPS is applied to MTA in order to guarantee the quality of voice data in actual HFC Internet service network, it is possible to smoothly perform voice data transmission in narrow upstream band which is a problem in actual commercial HFC network We also proposed a method to improve VoIP service by improving QoS of voice data in HFC Internet service network.