• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.199-202
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• 2002

본 논문에서는 사람의 청각 모델을 기반으로 잡음에 의해 손상된 음성 신호로부터 잡음 신호의 마스킹 특성과 신호에너지의 지각(知覺)을 나타내는 임계대역(critical band)에서의 잡음 에너지에 대한 지각 패턴인 noise excitation pattern을 이용한 잡음 에너지 차감과 잡음 추정 오차에 의한 변형된 음성신호 내의 순음(tonal) 성분과 비순음(non-tonal)성분의 보정을 통해 효과적인 음성 품질의 개선을 위한 연구를 하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.309-310
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• 2015

본 연구는 뇌졸중 등의 상지 기능 손상에 대하여 원격지에 위치하는 환자에게 치료와 진단을 포함하는 재활 콘텐츠를 제공하는 시스템을 개발하기 위한 설계를 목적으로 하고 있다. 설계 콘텐츠의 구조는 가상현실로 재활과 관련된 상지의 움직임을 제시하고 실제 움직임을 키넥트 센서를 이용하여 추적하여, 시각/청각/촉각 피드백을 제시함으로써 재활 치료 효과와 몰입감을 높이고 상지 운동 기능을 평가하는 것으로 구성된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1150-1158
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• 2013

Artificial cochlear implant system is known as the most efficient and widespread device to patients who have cochlear disorder. However, current commercialized artificial cochleas have inconveniences because of large volume size and high power consumption, requiring further research on improvements in terms of the size, power, and performance. In this paper, we will introduce our fully implantable artificial cochlear implant system, where small-size sensors and actuators are wirelessly connected, focusing on communication system design and its performance simulation.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.249-255
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• 2012

A cochlear implant system uses charge-balanced biphasic pulses that are known to reduce tissue damage than monophasic pulses. In this study, we investigated effect of pulse pattern on neural responses using a computer model, based on the Hodgkin-Huxley equation. Electric pulse phase, pulse duration, and phase gap have been systematically varied to characterize auditory nerve responses. The results show that neural responses, dynamic range and threshold are represented as a function of stimulus patterns and duration. The results could greatly extend to develop more efficient cochlear implant stimulation.

• Journal of Biomedical Engineering Research
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• v.20 no.4
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• pp.495-502
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• 1999

We propose efficient speech signal processing algorithms and a system for cochlear implant in this paper. The outer and the middle car which perform amplifying, lowpass filtering and AGC, are modeled by an analog system, and the inner ear acting as a time-delayed multi filter and the transducer is implemented by the DSP circuit which enables real-time processing. Especially, the basilar membrane characteristic of the inner ear is modeled by a nonlinear filter bank, and then tonotopy and periodicity of the auditory system is satisfied by using a pitch-synchronous multi-spectra(PSMS) method. Moreover, most of the speech processing is performed by S/W so the system can be easily modified. And as our program is written in C-language, it can be easily transplanted to the system using other processors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.953-959
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• 2010

We extracted bioactive materials from Codium fragile by enzymatic hydrolysis using four different proteases (Alcalase, Flavourzyme, Neutrase, and Protamex) and seven different carbohydrases (amyloglucosidase (AMG), Celluclast, Dextrozyme, Maltogenase, Promozyme, Termamyl, and Viscozyme), and evaluated their biological activities such as antioxidant, anti-acetylcholinesterase (AChE), and anti-inflammatory effects. All enzymatic hydrolysates showed good DPPH radical scavenging capacities, in particular, Flavourzyme and Promozyme hydrolysates possessed the highest activity. The two hydrolysates also exhibited strong hydrogen peroxide scavenging activity, $Fe^{2+}$ chelating activity, and reducing power in a dose-dependent manner. Furthermore, the two hydrolysates effectively protected DNA damage induced by hydroxyl radical by measuring the conversion of supercoiled DNA to the open circular DNA. All enzymatic hydrolysates also showed high anti-AChE inhibitory activities in a dose-dependent manner, and did not showed any significant cytotoxicity on RAW264.7 cells (p<0.05). In addition, the enzymatic hydrolysates significantly (p<0.05) inhibited lipopolysaccharide induced-nitric oxide production on RAW264.7 cells. These results suggest that the enzymatic extracts from Codium fragile would be good source as an ingredient of functional foods.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.570-575
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• 2021

Since humans live while feeling rich in their five senses, care must be taken not to damage their hearing in order to lead a happy life. Hearing damage suffered in a living environment is common in a partial band where a specific frequency band is first damaged. However, since the initial pain of hearing damage does not appear much, it is difficult to determine the symptoms in the early stages. In this paper, we proposed a high-speed measurement method that can easily and quickly self-measure hearing damage through a simple app. In this method, 9 pure tones compensated for gain for each voice soub-band are alternately heard in both ears, so that one's own hearing damage can be detected at high speed. When 18 tone pulses were heard for 30 seconds per person, 1 out of 12 subjects was identified as suspected of partial hearing damage. And when the test subjects were informed of the hearing determination method for the number of hearings, the participants themselves immediately determined whether their hearing was damaged. This measurement method simply judges the hearing of both ears within 30 seconds with a smart phone, so that hearing measurements that took more than 10 minutes in hospitals are relatively accurate, and it was found that hearing health can be maintained while reducing time and costs.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.203-206
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• 1997

본 연구는 G7 의료공학기술개발사업의 1차년도 연구결과이다. 본 연구의 최종목표는 청각계통중 내이의 손상에 의한 감각성 난청환자에게 소리를 인식할 수 있게 하는 한국형 인공와우의 개발, 전 음성 난청환자의 음성인식 효율을 높일 수 있는 한국형 인공이소골의 개발 그리고 인공와우 시술환자에게 적합한 재활용 프로그램을 개발하는데 있다. 이를 위하여 지난 1차년도에는 코클리어의 전기생리학적 현상을 규명하고, 이식전극시스템과 그 주변장치를 설계, 평가하였다. 그리고 한국인의 성인사체의 16귀를 측정하여 한국인 체형에 적합한 인공이소골의 설계기준을 확립하였다. 또한, 인공와우 시술 후 청력회복에 필요한 한국형 재활프로그램의 개발을 위하여 인공와우의 coding strategy에 따른 언어분별력 조사, 유소아의 어음특성분석등을 행하였다. 이 연구결과를 토대로 차기년도에는 상용화에 근접한 프로토타잎의 제품개발과 임상실험이 진행되리라 생각된다.

• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.223-229
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• 2021

To evaluate the protective effect of Codium fragile on fine dust (PM2.5)-induced cytotoxicity, we investigated its antioxidant activity and cell protective effect on PM2.5-exposed cells. The 40% ethanolic extract of C. fragile showed the highest total phenolic content, whereas the water extract of C. fragile showed the highest total polysaccharide content. The protective effect of the extracts on PM2.5-induced oxidative damage in nasal cavity (RPMI2650), lung (A549), brain (MC-IXC), hippocampus (HT-22), and microglia (BV-2) cells was evaluated by measuring the intracellular reactive oxygen species (ROS) content and cell viability. The results showed that the 40% ethanolic extract more efficiently inhibited ROS production than the water extract. In contrast, PM2.5-exposed cells treated with the water extract showed higher viability than those treated with the 40% ethanolic extract.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.3
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• pp.255-261
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• 2012

The skin is continuously exposed to environmental stresses. One of the most important stress factor is UV radiation. UV radiation causes a variety of biological effects on the skin, including inflammation, pigmentation, photoaging and cancer. Therefore in this study, we tried to search for skin-protective antioxidant materials from marine natural products (Porphyra Thalli, Laminariae japonicae thallus, Ostreae Concha, Sargassum Thallus, Undaria thallus, Haliotidis Concha, Agar, Codium thalli, Hizikia fusiforme thalli; HFE, Thalli) which exhibit protective activities against UVB-induced cytotoxicity and oxidative cell death and antiaging effects. As a results, UVB-induced cytotoxicity and cell death were effectively suppressed by treatment of Sargassum Thallus, Agar, Haliotidis Concha, Codium thalli, Thalli ethanol extracts. UVB-induced cell death was mediated by intracellular accumulation or ROS, which was significantly inhibited by treatment with marine natural products extracts. Also, The protective effect of these marine natural products seemed to be mediated by increased expression of type I collagen and Type I procollagen. These results suggest that marine natural products may have anti-aging effects new functional materials against oxidative stress-mediated skin damages.