• Phonetics and Speech Sciences
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• v.6 no.3
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• pp.91-99
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• 2014

Although it is well documented that patients with cochlear implant experience hearing difficulties when processing their first language, very little is known whether or not and to what extent cochlear implant patients recognize segments in a second language. This preliminary study examines how Korean learners of English identify English segments in a normal hearing and cochlear implant simulation conditions. Participants heard English vowels and consonants in the following three conditions: normal hearing condition, 12-channel noise vocoding with 0mm spectral shift, and 12-channel noise vocoding with 3mm spectral shift. Results confirmed that nonnative listeners could also retrieve spectral information from vocoded speech signal, as they recognized vowel features fairly accurately despite the vocoding. In contrast, the intelligibility of manner and place features of consonants was significantly decreased by vocoding. In addition, we found that spectral shift affected listeners' vowel recognition, probably because information regarding F1 is diminished by spectral shifting. Results suggest that patients with cochlear implant and normal hearing second language learners would experience different patterns of listening errors when processing their second language(s).

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.648-654
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• 2010

In this paper, a navigation system was designed, and performance tested in order to confirm the safety improvement of the GNSS(Global Navigation Satellite System)-based AGV(Autonomous Guided Vehicle) which used only position information on of GNSS. We developed DR(Dead Reckoning) navigation system that involve the use of GNSS abnormal positoning error detection and GNSS signal outage. The test results show that GNSS positioning error is detection can be archived with an error of more than 0.15m. In addition, the DR driving position error is 1.5m for an 8s GNSS positioning service outage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.388-393
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• 2012

Vibration condition monitoring at low rotational speeds is still a challenge. Acoustic emission (AE) is the most used technique when dealing with low speed bearings. At low rotational speeds, the energy induced from surface contact between raceway and rolling elements is very weak and sometimes buried by interference frequencies. This kind of issue is difficult to solve using vibration monitoring. Therefore some researchers utilize artificial damage on inner race or outer race to simplify the case. This paper presents vibration signal analysis of low speed slewing bearings running at a low rotational speed of 15 rpm. The natural damage data from industrial practice is used. The fault frequencies of bearings are difficult to identify using a power spectrum. Therefore the relatively improved method of empirical mode decomposition (EMD), ensemble EMD (EEMD) is employed. The result is can detect the fault frequencies when the FFT fail to do it.

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.263-270
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• 2007

New mono- and bis-Cu(II)-triazacyclononane(tacn) complex that conjugated with 9-aminoacridine were synthesized, and their binding modes and DNA cleavage activity were investigated in this study. When the classic intercalator, 9-aminoacridine, was conjugated to mono- and bis-Cu(II)-tacn complexes, a significant red-shift and hypochromism in absorption spectrum was apparent in the acridine absorption region upon binding to DNA. Furthermore, the magnitude of the negative reduced linear dichroism signal in the substrate absorption region appeared to be larger than that in the DNA absorption region. These spectral observations indicated that the acridine moiety intercalated when the Cu(II)-tacn complex was conjugated. In contrast, from a close analysis of the circular and linear dichroism spectrum, the aminoacridine-free bis-Cu(II)-tacn complex was concluded to bind at the phosphate groups of DNA. The 9-aminoacridine-free-bis-Cu(II)-tacn complex produces the nicked and linear DNA. On the other hand, 9-aminoacridine conjugated mono-and bis-Cu(II)-tacn complexes showed unspecific binding with negligible DNA cleavage.

• ETRI Journal
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• v.37 no.5
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• pp.867-876
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• 2015

This paper proposes an efficient interference control scheme for vehicular moving networks. The features of the proposed scheme are as follows: radio resources are separated into two resource groups to avoid interference between the cellular and vehicle-to-vehicle (V2V) links; V2V links are able to share the same radio resources for an improvement in the resource efficiency; and vehicles can adaptively adjust their transmission power according to the interference among the V2V links (based on the distributed power control (DPC) scheme derived using the network utility maximization method). The DPC scheme, which is the main feature of the proposed scheme, can improve both the reliability and data rate of a V2V link. Simulation results show that the DPC scheme improves the average signal-to-interference-plus-noise ratio of V2V links by more than 4 dB, and the sum data rate of the V2V links by 15% and 137% compared with conventional schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.417-429
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• 1998

The advance of the MPEG (Moving Picture Expert Group) and the DSP (Digital Signal Processing) technologies lead the emergence of the information appliances, which are gradually digitalized and embedded the high-speed networking function. However, there are some difficulties in establishing any one specific model, since standardization of the scale and function of home ATM network is being progressed by standardization organizations and no absolute model has been defined. This paper consider topologies for a home ATM network, such a star-type, tree-type, and mesh-type topology, by comparing the structure, functional characteristics and performance. From this analysis we suggest the design method of the home ATM network.

• Natural Product Sciences
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• v.13 no.4
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• pp.283-288
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• 2007

Acanthopanacis Cortex (AC) has been popularly used as an herbal medicine for medical treatment of rheumatoid arthritis, insomnia, impotence and diabetes. Here, we investigated immunostimulating effects of the aqueous extract of AC on macrophage. We studied nitric oxide (NO) and tumor necrosis factor (TNF)-${\alpha}$ release in response to AC treatment, as they are important secretory products of macrophage. AC alone induce the NO and TNF-${\alpha}$ production. AC increase c-Jun NH2-terminal kinase 1/2 (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation but does not p38 activation in RAW 264.7 cells. Also AC resulted in the enhanced cell-surface expression of CD80 and CD14. In addition, AC resulted in enhanced T cell-stimulatory capacity and increased T cell secretion of interferon (IFN)-gamma. After feeding with AC to mouse for 10 days, the change of $CD28^+$ and $CD40^+$ population was analyzed. AC increased $CD28^+$ population in splenocytes in vivo. These studies indicate that AC induces macrophage activation and suggest the possible use of AC in macrophage-based immunotherapies.

• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.125-128
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• 2008

사상의학은 개인별 체질의 분류에 따른 맞춤형 의학으로 우리나라 고유의 독특한 전통 의학이다. 이와 같은 사상의학에서 가장 중요하게 여겨지는 것이 사상체질의 정확한 분류이다. 따라서 사상체질 분류에 대한 객관적 요소의 확보 및 진단 지표 마련이 시급하게 해결되어야 할 과제이다. 이를 위해 본 논문에서는 사상체질 분류의 객관화, 정량화 및 시각화를 위해 얼굴 영상 신호와 음성 신호를 분석하여 결과값을 추출하고 체질별 집단군간의 차이점을 비교하여 사상체질 분류 시스템을 구현하고자 한다. 특히 영상 및 음성 신호는 성별, 연령별, 지역별 등의 구분에 따라 달라지기 때문에 본 논문에서는 40에서 50대 사이의 장년 여성을 대상으로 서울지역 거주자에 한해 사상체질 집단군을 구성하고 이들의 영상 및 음성 신호를 추출하여 체질간 비교, 분석을 수행하고자 한다. 최종적으로 실험을 통한 연구 결과의 유의성을 입증하고자 한다.

• Journal of Radiation Industry
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• v.11 no.3
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• pp.139-144
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• 2017

To evaluation of clinical usefulness for B1+RMS limits, we compared image quality of Routine, Specific absorption rate (SAR) and Root mean square (RMS) protocol. 5 volunteers underwent Magnetic Resonance Imaging (MRI) scan of the brain using three different protocols. We draw Region of interest ROI in cortex, white matter, gray matter, putamen and thalamus of axial plan. Signal to noise ratio (SNR) were evaluated in each area and Contrast to noise ration (CNR) were evaluated between white matter and gray matter. Qualitative evaluation was used to score each ROI. B1+RMS is confirmed its usefulness compared to conventional SAR standard on the aspect of improvement of image quality, reduction of scan time and easy adjusting parameter.

• ETRI Journal
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• v.42 no.6
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• pp.837-845
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• 2020

The objective of this study was to implement an in vitro exposure system for 28 GHz to investigate the biological effects of fifth-generation (5G) communication. A signal source of 28 GHz for 5G millimeter-wave (MMW) deployment was developed, followed by a variable attenuator for antenna input power control. A power amplifier was also customized to ensure a maximum output power of 10 W for high-power 28-GHz exposure. A 3-dB uniformity over the 80 mm × 80 mm area that corresponds to four Petri dishes of three-dimensional cell cultures can be obtained using a customized choke-ring-type antenna. An infrared camera is employed for temperature regulation during exposure by adjusting the airflow cooling rate via real-time feedback to the incubator. The reported measurement results confirm that the input power control, uniformity, and temperature regulation for 28-GHz exposure were successfully accomplished, indicating the possibility of a wide application of the implemented in vitro exposure system in the fields of various MMW dose-response studies.