• 전력전자학회논문지
• /
• 제27권5호
• /
• pp.446-454
• /
• 2022

This study proposes a carrier-based pulse width modulation (PWM) method for leakage current reduction and neutral point (NP) current control in a three-phase three-level converter, which is a carrier-based PWM version of the previously proposed low-frequency common mode voltage PWM. Three groups of space vectors with the same common mode voltage are used. When the averaged NP current needs to be positive or negative, the specific groups are employed to produce low-frequency common mode voltages. The validity of the proposed PWM method is verified through experiments.

• 대한수학회보
• /
• 제34권3호
• /
• pp.411-419
• /
• 1997

Using the theory of strongly continuous cosine families, we prove controllable of nonlinear second order control system and give an application.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.101.3-101
• /
• 2001

By setting a refractor with a certain angle against the optical axis of the CCD camera lens, the image of a measuring point recorded on the image plane is displaced by the corresponding amounts related to the distance between the camera and the measuring point. When the refractor that keeps the angle against the optical axis is rotated physically at high speed during the exposure of the camera, the image of a measuring point draws an annular streak. Since the size of the annular streak is inversely proportional to the distance between the camera and the measuring point, the 3D position of the measuring point can be obtained by processing the streak. In this paper, for one of the applications of our system, the measurement of a moving surface is introduced. In order to measure the moving surface, multi laser spots are projected on the surface of object. Each position of ...

• Journal of the Optical Society of Korea
• /
• 제12권2호
• /
• pp.69-78
• /
• 2008

EPONs are a low cost, high speed solution to the bottleneck problem of broadband access networks. To support point-to-point and shared LAN emulation, EPONs use the multi-point control protocol (MPCP), which uses logical link identification (LLID) forframe tagging and filtering between the OLT and ONUs. In this paper, ONU-based multicast or multiple shared LAN emulation for IPTV services is proposed using logical group identification (LGID). Using ONUbased VLAN services, EPONs can support separate and secure connections between providers and subscribers in a simple manner. Also, differentiated IPTV channel packages can be delivered through EPONs by implementing ONU-based VLAN and IGMP snooping mechanisms.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 추계종합학술대회
• /
• pp.1019-1022
• /
• 2005

최근 정보 통신 기술의 급속한 발전에 의해 음성 신호 처리에 관련된 많은 연구가 진행됨에 따라 피치 주기는 음성 인식, 화자 식별, 음성 분석 및 합성 등과 같은 많은 응용분야에서 중요한 요소로써 적용되고 있다. 이러한 피치 주기 검출에 관련된 시간 영역과 주파수 영역에서의 많은 알고리즘이 제안되었으며, 시간 영역의 피치 검출 알고리즘의 하나인 AMDF(average magnitude difference function)는 각 valley점의 거리를 피치 주기로 계산한다. 그러나 피치 주기 검출을 위한 valley점 선정에 있어서 알고리즘이 복잡해지는 문제점이 발생한다. 따라서 본 논문에서는 AMDF의 회전변환을 이용하여 전체 최소 valley점을 음성 신호의 피치 주기로 인식하는 간단한 알고리즘을 제안하였으며, 음성의 시작구간에 대해 경계값을 설정하여 피치 주기 선정에 대한 판단기준으로 사용하였다. 그리고 제안한 알고리즘을 시뮬레이션을 통해 기존의 방법들과 비교하였다.

• 한국농공학회논문집
• /
• 제57권5호
• /
• pp.129-137
• /
• 2015

The objective of this study was to test the non-point source pollution (NPS) control by the vegetated ridge and silt fence through field monitoring. The experiment plots were established with three sizes which are 5 m width by 22 m length with 8 %, 3 % slope and 15m width by 15 m length with 6 % slope. Flumes with the floating type stage gages were installed at the outlet of each plot to monitor the runoff. For a rainfall monitoring, tipping bucket rain gage was installed within the experiment site. Water quality samples were monitored during the heavy rainfall occurred. The amount of rainfall from 4 monitored events ranged from 27.6 mm to 130 mm. The runoff reduction rate could vary depending on slope, soil, crop growth condition, rainfall amount, rainfall intensity, antecedent moisture condition, and many other factors. The runoff from vegetated ridge and silt fence treatment plots was 24.05 % and -8.28 % lower than that from control plot, respectively. The monitoring results showed that the average pollution loads reduced by vegetated ridge compared to control were BOD 36.62~53.60 %, SS 40.41~73.71 %, COD 39.34~56.41 %, DOC 49.08~53.67 %, TN 26.74~67.23 %, and TP 52.72~91.80 %; by silt fence compared to control were SS 41.73 %, COD 1.93 %, and TN 2.38 %. The paired t-test result indicated that the vegetated ridge and silt fence were statistically significant effect in SS load reduction, with a 5 % significant level. Monitored results indicated that vegetated ridge and silt fence were both effective to reduce the pollutant from the field surface runoff.

• 한국산학기술학회논문지
• /
• 제16권4호
• /
• pp.2602-2608
• /
• 2015

본 연구는 고춧가루의 HACCP(Hazard Analysis Critical Control Point) 시스템 적용에 필요한 미생물학적 위해 요소분석을 위한 목적으로 2014년 1월 10일~2014년 6월 13일까지 충주시 동량면 소재에 있는 용금농산에서 수행하였다. 고춧가루 제품의 모든 공정 단계들을 파악하여 공정흐름도를 작성하였고 미생물학적 위해를 제어할 수 있는 자외선살균공정에서 살균 시간을 변화시키면서 미생물의 변화를 시험한 결과 자외선 등 $20W{\times}12EA$, 살균 시간은 $63{\pm}3$초를 한계기준으로 결정하였다. 자외선살균 후에는 위해 미생물 검사 결과는 안전하나 제조환경과 작업자의 미생물 검사 결과 주기적인 세척 및 소독을 실시하여 미생물학적 위해를 감소시키고 작업자 위생교육 등을 통하여 개인위생을 준수해야 할 것으로 판단된다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2007년도 하계학술대회 논문집
• /
• pp.74-76
• /
• 2007

In this paper a maximum power point tracking(MPPT) techniques for power of PV(photovoltaic) systems are presented using boost converter for a connected single phase inverter. On the basic principle of power generation for the PV module, algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT's switch in full bridge. Furthermore a low cost control system for solar energy conversion using the DSP is developed, based on boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• 한국정보통신학회논문지
• /
• 제17권11호
• /
• pp.2627-2635
• /
• 2013

본 논문에서는 새로운 MPPT 제어기능을 갖는 빛에너지 하베스팅 회로를 제안한다. 기존의 빛 에너지 하베스팅 회로에서는 MPPT(Maximum Power Point Tracking) 기능을 구현하기 위해 전력 변환기(power converter)를 동작시키기 위한 클록의 주파수나 듀티 싸이클(duty cycle)을 지속적으로 변화시키는 방법을 사용하고 있다. 본 논문에서는 전력변환기에 전력 공급을 위한 전력 스위치의 듀티 싸이클을 제어하여 MPPT 기능을 구현하는 새로운 방법을 제안한다. 제안된 회로는 $0.35{\mu}m$ CMOS 공정으로 설계 되었으며 칩 면적은 패드를 포함하여 $770{\mu}m{\times}800{\mu}m$이다.

• Archives of Plastic Surgery
• /
• 제35권5호
• /
• pp.533-538
• /
• 2008

Purpose: Sensory changes in the upper limb are complications of a mastectomy with immediate breast reconstruction with the treatment of breast cancer. The purpose of this study is to clarify whether immediate breast reconstruction worsens the sensory changes. Methods: From March 2004 to December 2005, 20 patients who had a mastectomy with immediate breast reconstruction(reconstruction group) were compared with 23 patients who had a mastectomy alone(control group). All patients had stage I or II breast cancer. The sensory changes were assessed in a blind manner by one examiner that used light touch sensation, static two-point discrimination, pain, vibration, hot and cold temperature perception. The sensory changes were identified along the sensory dermatome for diagnosing the damaged nerves. The following factors and their relationship with the sensory changes were analyzed : age, complications, and the mastectomy method. Results: There was no statistical difference in the static two-point discrimination, pain, vibration, hot and cold temperature perception between the two groups. However, the ability to recognize light touch was significantly better(p=0.045) in the reconstruction group than in the control group. The main site of sensory change was the proximal and medial portion of the upper limb in both groups. At these sites, the mean value of Semmes-Weinstein monofilament was $1.01g/mm^2$(reconstruction group 0.82, control group 1.17) and 2-point discrimination was 51.74(converted to perfect score of 100; reconstruction group 42.50, control group 59.78). The total rate of early complications was found to be significantly lower(p=0.006) in the reconstruction group than in the control group. Conclusion: These findings suggest that an immediate breast reconstructive procedure following a mastectomy is as safe as or safer than a mastectomy alone with respect to postoperative sensory changes of the ipsilateral upper limb.