• 설비공학논문집
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• 제4권2호
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• pp.65-71
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• 1992

In most absorption machines, absorption enhancement has been achieved by adding small amount of surfactant additive, which introduced the surface tension difference between absorbent and surfactant droplets in the vapor absorption. The aim of this study is to understand a basic mechanism of Marangoni convection and its effectiveness in the vapor absorption enhancement. In this study, nonflowing aqueous solution of LiBr 60 mass% was exposed to saturated water vapor under the condition that two dropwises surfactant were fixed on the absorbent surface. Our experiments achieved to visualize the enhanced heat and mass transfer phenomena by the effect of Marangoni convection through the laser holographic interferometry. Also, Marangoni convection behavior was obtained by using tracer method.

• 전자공학회논문지A
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• 제32A권8호
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• pp.86-93
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• 1995

Linwidth enhancement factor .alpha., linwidth, chirping and differential gain characteristics were measured and compared for each DFB-LDs containing active layers composed of bulk, MQW, and S-MQW, respectively. .alpha. of 6, 4 and 3.2 and chirping measured under 2.5Gbps modulation of 1.29nm, 0.67nm and 0.48nm were given for DFB-LDs of bulk, MQW and S-MQW active layers, respectively. And S-MQW has the largest differential gin of 2.4*10$^{-15}$ cm$^{2}$ (S-MQW) compared to the of 5.4*10$^{-16}$ cm$^{2}$(bulk) and 8.6*10$^{-16}$ cm$^{2}$(MQW). Linewidth enhancement facter .alpha. of less than 2 is expected with p-type modulation doped S-MQW DFB-LD.

• BMB Reports
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• 제49권10호
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• pp.566-571
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• 2016

Forskolin (FSK), an adenylyl cyclase activator, has recently been shown to enhance nucleotide excision repair (NER) upon UV exposure. However, our study revealed that this effect was detected in human skin epithelial ARPE19 cells only in growing cells, but not in non-cycling cells. When the cells were grown at low density (70% confluence), FSK was capable of stimulating cAMP responsive element binding (CREB) phosphorylation, a marker for FSK-stimulated PKA activation, and resulted in a significant increase of NER activity compared to control treatment. However, cells grown under 100% confluent conditions showed neither FSK-induced CREB phosphorylation nor the resulting NER enhancement. These findings indicate that cellular growth is critical for FSK-induced NER enhancement and suggest that cellular growth conditions should be considered as a variable while evaluating a reagent's pharmacotherapeutic efficacy.

• 설비공학논문집
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• 제7권3호
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• pp.450-460
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• 1995

A modified circulating fluidized bed heat exchanger under severe fouling condition is developed. The effects of fouling deposits on the performance of a heat exchanger are investigated. The principle and operating characteristics of a circulating fluidized bed heat exchanger are dicussed. A modified circulating fluidized bed heat exchanger shows more stable operating than the other circulating fluidized bed heat exchanger. The characteristics of self cleaning and heat transfer enhancement of a circulating fluidized bed heat exchanger are studied. The movement of spherical particles in a tube is visualized and heat transfer enhancement and scale reduction mechanism by particles are investigated.

• Bulletin of the Korean Chemical Society
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• 제26권10호
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• pp.1560-1564
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• 2005

The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from $2.5\;{\times}\;10^{-8}\;to\;1\;{\times}\;10^{-6}$ mol/L, and the detection limit was found to be $7.5\;{\times}\;10^{-9}$ mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2014년도 하계학술대회
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• pp.163-165
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• 2014

In this paper, we propose a world's first programmable video processing platform for video quality enhancement of 8K ($7680{\times}4320$) UHD (Ultra High Definition) TV at 60 frames per second. To support huge computation and memory bandwidth of video quality enhancement for 8K resolution, the proposed platform has unique features like symmetric multi-cluster architecture for data partitioning, ring data-path between clusters to support data pipelining, on-the-fly processing architecture to reduce DDR bandwidth, flexible hardware to accelerating common kernel in video enhancement algorithms. In addition to those features, general programmability of SRP (Samsung reconfigurable processor) as main core of the proposed platform makes it possible to upgrade continuously video enhancement algorithm even after the platform is fixed. This ability is very important because algorithms for 8K DTV is under development. The proposed sub-system has been embedded into SoC (System on Chip) and new 8K UHD TV using the programmable SoC is expected at CES2015 for the first time in the world.

• 한국연소학회지
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• 제1권1호
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• pp.51-55
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• 1996

An experimental investigation has been made with the objective of studying the limits of equivalence ratio on mixing enhancement in a tone excited jet flame. The jet is pulsed by means of a loudspeaker-driven cavity and rich flames(${\phi}>1.5$) are used. The excitation frequency is chosen for the resonant frequency identified as a pipe resonance due to acoustic excitation. Methane, propane and butane are used to examine the effect of mixture property on the limit of equivalence ratio. Mixing is always enhanced in a methane/air flame as the excitation intensity increases. Constant lower limits of equivalence ratio for mixing enhancement are present in cases of propane/air and butane/air flames irrespective of mean mixture velocities. The equivalence ratio limits are also found to be related to the flame instability ; the lower Le, the higher the limit of equivalence ratio. Under the equivalence ratio limits, cellular flames are generated as the excitation intensity increases. The amplitude of oscillating velocity for generating a cellular flame in the equivalence ratio limit is proportional to a mean mixture velocity irrespective of fuels.

• 한국결정성장학회지
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• 제14권2호
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• pp.73-77
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• 2004

수열처리법을 이용하여 저품위의 잠비아산 천연 자수정의 색상 개선을 행하였다. 수열처리 조건은 다음과 같다. 즉, 수열용매 6M-HCI, 반응온도 $300^{\circ}C$, 반응시간 30시간, 충진율 40%이었다. 이와 같은 조건에서 고품질 적자색의 자수정이 얻어졌다. ICP/AES 결과로부터 색 향상은 잠비아산 자수정의 내부에 존재하는 Fe 원소의 함량이 영향을 미치는 것을 알았다. 또한 UV-VIS-NIR분석결과 처리전 잠비아산 수정과 비교해 550nm 흡수피크가 작아짐을 볼 수 있었다. 본 연구의 결과는 수열처리가 잠비아산 자수정의 상업적인 가치 증가에 있어서 적합한 방법이었다.

• 전기학회논문지
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• 제65권6호
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• pp.1032-1037
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• 2016

In this paper, the method of isolation enhancement for the mobile phone MIMO antenna of LTE class 40(2300~2400MHz) was studied. Design of MIMO antenna was based on the hybrid antenna that operates both a monopole and an IFA(Inverted F Antenna). A structure for the isolation enhancement which controls induced electric field on the ground plane is located between MIMO antenna, and was not connected with the ground but apart 0.3mm. A MIMO antenna that operates on class 3~40(1710~2400MHz) of LTE service bands and a structure for the isolation enhancement at the class 10 band were designed. VSWR measurement of implemented antenna on the FR4 board showed within 3:1 at entire design bands, and isolation between antennas at the class 40 band was less than -30dB. Isolation was enhanced more than 20dB by the studied structure. ECC(Envelope Correlation Coefficient) for MIMO performance was under 0.1, and antenna average gain and efficiency measured in the anechoic chamber were -4.28~-1.40dBi and 37.32~72.36% respectively.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.638-648
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• 2013

Together with the GPS-based approach, geo-location through mobile communication networks is a key technology for location-based service. To save the cost, most geo-location system is implemented on the existed network service, which has a cellular structure. Still, multilateration is limited in cellular structure because it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. This low hearability in the receiver is caused by co-channel interference and multipath environment. Therefore, hearability enhancement is necessary for multilateration under multipath and interference environment. Former time domain based hearability methods were designed for real signals. However, orthogonal frequency division multiplexing (OFDM) signal, which its usage has been increased in digital wireless communication, is a complex signal. Thus, different hearability enhancement method is needed for OFDM signals. This paper proposes a hearability enhancement method for forward-link multilateration using OFDM signals, which employ interference cancellation and multipath mitigation. A novel interference cancellation and multipath mitigation strategy for complex-valued OFDM signals is presented that has an iterative structure. Simulation results show that the proposed multilateration method provides the user's position with an accuracy of less than 80m through the mobile WiMAX cellular network in multipath environment.