• 한국전기전자재료학회논문지
• /
• 제20권12호
• /
• pp.1087-1092
• /
• 2007

We developed the 4-channel Light Medical Therapy Apparatus for Skin Injury Cure using a high brightness LED. This equipment was fabricated using a micro-controller and a high brightness LED, and designed to enable us to control light irradiation time, intensity and reservation. In this paper, the designed device was used to find out how high brightness LED light affects the skin injury of SD-Rat(Sprague-Dawley Rat). In the experiment, $1\;cm^2$ wounds on the skin injury of SD-Rat(Sprague-Dawley Rat) were made. Light irradiation group and none light irradiation group divided, each group was irradiated one hour a day for 14 days. In result, compared with none light irradiation group, the lower incidence of inflammation and faster recovery was shown in light irradiation group.

• ETRI Journal
• /
• 제26권5호
• /
• pp.391-396
• /
• 2004

In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real-time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short-term fairness as well as long-term fairness for various real-time traffic.

• 한국가시화정보학회지
• /
• 제6권1호
• /
• pp.53-58
• /
• 2008

We carried out the experiments which controled the periodic jet in front of the fence to alter the fence wake. The experiments were performed in circulating water channel and the vertical fence was submerged in the boundary layer. The frequency, jet nozzle distance and speed of jet passing the slit were investigated. Each case divided into 20 phases and phase-averaged results were compared with uncontrolled fence flow. From the results, we found the specific frequency and nozzle distance which were good for reducing the reattachment length. In this case, the reattachment length was decreased 35% compared with the uncontrolled fence flow.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권1호
• /
• pp.123-140
• /
• 2011

In this paper, we propose an Energy Efficient Media Access Control (EE-MAC) protocol for wireless sensor networks. The proposed scheme is designed to save power consumption and guarantee quality-of-service for real-time traffic. EE-MAC uses the superframe structure which is bounded by the transmission of a beacon frame and can have an active and an inactive portion. The active period is divided into the contention free period (CFP) for real-time traffic transmission and the contention access period (CAP) for non-real-time traffic transmission. We propose the exclusively allocated backoff scheme which assigns a unique backoff time value to each real-time node based on bandwidth allocation and admission control. This scheme can avoid collision between real-time nodes by controlling distributed fashion and take effect a statistical time division multiple access. We also propose the algorithm to change the duty cycle adaptively according to channel utilization of media depending on network traffic load. This algorithm can prolong network lifetime by reducing the amount of energy wasted on idle listening.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.574-578
• /
• 2008

In order to achieve thrust vector control and discharge stabilization in Hall thrusters, the azimuthal nonuniformity of propellant flow rate in an acceleration channel was created. A plenum chamber was divided into two rooms by two walls and propellant flow rate supplied to each section was independently controlled. In a magnetic layer type Hall thruster, steering angle of up to ${\pm}2.3$ degree was achieved. In an anode layer type Hall thruster, discharge current oscillation amplitude was decreased with the normalized differential mass flow rate.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권4호
• /
• pp.1904-1921
• /
• 2019

In this paper, we investigate the problem of secure communications in multiple-input-multiple-output interference networks from the perspective of physical layer security. Specifically, the legitimate transmitter-receiver pairs are divided into different categories of active and inactive. To enhance the security performances of active pairs, inactive pairs serve as cooperative jammers and broadcast artificial noises to interfere with the eavesdropper. Besides, active pairs improve their own security by using joint transceivers. The encoding of active pairs and inactive pairs are designed by maximizing the difference of mean-squared errors between active pairs and the eavesdropper. In detail, the transmit precoder matrices of active pairs and inactive pairs are solved according to game theory and linear programming respectively. Experimental results show that the proposed algorithm has fast convergence speed, and the security performances in different scenarios are effectively improved.

• 한국정보통신학회논문지
• /
• 제24권5호
• /
• pp.678-681
• /
• 2020

In this paper, we analyzed the noise figure of cascode low noise amplifier (LNA) based on the measured data of 65nm CMOS devices. By using the channel thermal noise model of transistors, we expanded noise figure equation and divided the equation into three parts to see its contributions to noise figure. We also varied design parameters such as bias point, transistor gate width, and operating frequency. Our results show that different noise sources dominate at the different operating frequencies. One can easily find the noise transition frequency with device models in ahead of the practical design. Therefore, this research provides a low noise design approach for different operating frequencies.

• 대한원격탐사학회지
• /
• 제36권2_2호
• /
• pp.277-292
• /
• 2020

본 연구에서는 천수만 황도 갯벌 지역을 대상으로 UAV 자료와 객체기반영상분석 방법을 사용하여 대축척 갯벌 표층 퇴적상 분류도를 작성하고, 정확도 검증을 수행하여 정밀한 표층 퇴적상 분류의 가능성과 보다 정확한 분류 방법에 대해 제시하였다. 이를 위해 고해상도 UAV 자료에서 가시광 영역의 정사영상과 수치표고모델(DEM), 조류로 밀도 등 퇴적상 분류 시 영향을 주는 요인들을 추출하고, 통계학적 분석 방법을 통해 퇴적상에 따른 요인들의 주성분을 분석하였다. 주성분 요인을 바탕으로 퇴적상 분류 시 사용할 입력 자료를 (1) 가시광 영역의 스펙트럼, (2) 지형 고도와 조류로 밀도, (3) 가시광 영역의 스펙트럼과 지형 고도 및 조류로 밀도로 구분하였으며, 이를 기반으로 객체기반영상분석 분류방법에 입력 자료를 적용하여 대축척 갯벌 표층 퇴적상 분류도를 추출하였다. 입력 자료의 조건에 따라 표층 퇴적상 분류를 수행한 결과, folk 분류 기준을 따르는 6가지의 표층 퇴적상으로 분류하였고, 가시광 영역의 스펙트럼과 지형 고도, 조류로 밀도를 사용할 경우 전체 정확도가 63.04%, Kappa 지수가 0.54로 가장 효과적으로 표층 퇴적상을 분류하였다.

• 한국해양학회지:바다
• /
• 제3권4호
• /
• pp.261-270
• /
• 1998

본 연구는 경기만의 저서다모류 군집의 분포와 종조성을 파악하기 위하여 1995년 12월에 수행되었다. 저서동물의 평균서식밀도는 557 개체/$m^2$이었고, 우점 동물군은 다모류로서 출현종수는 60 종, 서식밀도는 488 개체/$m^2$이었다. 저서다모류의 서식밀도는 인천항을 중심으로한 염하수로 일대 해역에서 가장 높았고, 영종도와 송도 주위의 조간대 지역과 주수로를 포함한 외해역에서는 낮았다. 최우점종은 Heteromastus filiformis이었으며(다모류 중 47.3%), 다음은 Nephtys polybranchia, Tharyx sp., Sternaspis scutata의 순이었다. 우점종의 종조성에 기초한 집괴분석 결과 경기만은 외해역/수로역, 인천항, 영종도조간대, 송도조간대의 네 해역으로 구분되었다. 외해역과 수로역은 출현종수가 가장 많아 다양도지수가 가장 높은 정점군이며, 인천항은 다모류의 서식밀도가 가장 높은 정점군이다. 특히 인천항은 H. filiformis가 극우점하는 지역이다. 경기만에서 수행된 이전의 연구 결과와 비교하면, 종수나 서식밀도는 최근 10 년간 크게 변화하지 않았다고 볼 수 있다. 우점종은 각 연구마다 차이를 보이나, 대체로 버들갯지렁이과, 실타래갯지렁이과, 얼굴갯지렁이과에 속하는 소형의 기회주의종들 이었다. 이러한 사실은 경기만의 유기물 오염이 꾸준히 진행되고 있음을 지시하며, 특히 본 연구 결과는 오염의 중심지가 인천항이며, 시화방조제 인근해역의 저서동물군도 극도로 불안정한 상태에 있음을 나타낸다.

• Korean Journal of Acupuncture
• /
• 제27권1호
• /
• pp.125-142
• /
• 2010

Objectives: The purpose of this study was to identify the effectiveness of neuronal activities for the acupuncture and laser acupuncture application. Methods: The subject were divided into 7 groups as control group without acupuncture, acupuncture treatment with tonify manipulation with the direction of channel at HT9, LR1(AT-A), acupuncture treatment with purge manipulation against the direction of channel at HT3, Kl10(AT-B), acupuncture treatment with tonify manipulation with the direction of channel at HT9, LR1 and purge manipulation against the direction of channel at HT3, KI10(AT-C), laser acupuncture treatment with red light 658 nm at HT9, LR1(LAT-A), laser acupuncture treatment with green light 532 nm at HT3, KI10(LAT-B), laser acupuncture treatment with red light 658 nm at HT9, LR1 and green light 532 nm at HT3, KI10(LAT-B). Antiapopotic effect of acupuncture was observed by Bax, Bcl-2 and cytochrome C. Neuroprotective effect of acupuncture was observed by cresyl violet and ChAT. Results: AT-A, AT-B, AT-C, LAT-A, LAT-B and LAT-C groups were significantly increased comparing the control groups in expression ChAT and in neuroprotective effect by cresyl violet. AT-A, AT-B, AT-C, LAT-A, LAT-B and LAT-C groups were significantly decreased comparing the control groups in expression Bax. AT-C, LAT-A, LAT-B and LAT-C groups were significantly increased comparing the control groups in expression Bcl-2. AT-A, AT-B, AT-C, LAT-A, LAT-B and LAT-C groups were significantly decreased comparing the control groups in Bax/Bcl-2 ratio. LAT-B and LAT-C groups were significantly decreased comparing the control groups in expression cytochrome C. Conclusions: The acupuncture with tonify and purge manipulation and laser acupuncture with red and green light could be effective for antiapopotic and neuroprotective effect in focal brain ischemia.