• 호남수학학술지
• /
• 제37권4호
• /
• pp.595-608
• /
• 2015

In this paper, as a survey paper, we review many works related to fixed point theory for digital spaces using Lefschetz fixed point theorem, Banach fixed point theorem, Nielsen fixed point theorem and so forth. Besides, we refer some properties of the fixed point property of a digital k-retract.

• Journal of Information Processing Systems
• /
• 제13권3호
• /
• pp.491-499
• /
• 2017

In this study, we proposed a new approach to segment ground and nonground points gained from a 3D laser range sensor. The primary aim of this research was to provide a fast and effective method for ground segmentation. In each frame, we divide the point cloud into small groups. All threshold points and start-ground points in each group are then analyzed. To determine threshold points we depend on three features: gradient, lost threshold points, and abnormalities in the distance between the sensor and a particular threshold point. After a threshold point is determined, a start-ground point is then identified by considering the height difference between two consecutive points. All points from a start-ground point to the next threshold point are ground points. Other points are nonground. This process is then repeated until all points are labelled.

• 한국컴퓨터정보학회논문지
• /
• 제22권8호
• /
• pp.63-72
• /
• 2017

In this paper, we propose a security architecture for HDLC-based T4 class common data link. The common data links are composed of point-to-point, multi-to-point, and point-to-multi mode. For multi-to-point mode, one node has a bundle of point-to-point links with different end-point on the other side of the links. Thus multi-to-point mode can be considered as a bundle of point-to-point mode. Point-to-multi mode is broadcasting link. For point-to-point mode we adopted robust security network scheme to establish a secure data link, and for multi-to-point mode we use broadcast encryption scheme based on ID-based cryptography to distribute encryption key for broadcasting message encryption. We also included MACsec technology for point-to-point data link security. Computational and communicational complexity analysis on the broadcast encryption have been done.

• Journal of Acupuncture Research
• /
• 제19권5호
• /
• pp.28-34
• /
• 2002

Objective : The aim of this research was to investigate the depressive effect of acupuncture on Gangap-point and depletion on Taech'u-point in stroke patients. Methods : We measured the blood pressure of the patients who were admitted in the Oriental Medical hopital of Dongeui medical center from 21. Oct. 2001. to 20. Jan. 2002. 19 stroke patients were devided into two groups. 12 patients were treated by acupunctured on Gangap-point. The other 7 patients were treated by depletion on Taech'u-point. The activity of daily living was measured. If systolic blood pressure was over 160 mmHg or diastolic blood pressure was over 90 mmHg, acupunctured on Gangap-point and depletion on Taech'u-point were performed. Then 30minutes and 60minutes later, systolic, diastolic blood pressure and pulse rates were measured Results : After 30 minute treatment. both acupuncture on Gnagap-point and depletion on Taech'u-point significantly depressed the systolic blood pressure. After 60 minute treatment. only depletion on Taech'u-point were statistically significant in depressing the systolic blood pressure. Pulse rates were not significantly changed. Conclusion : These results suggest that depletion on Taech'u-point is more effective in depressing the systolic blood pressure than acupuncture on Gnagap-point.

• Journal of Information Processing Systems
• /
• 제16권3호
• /
• pp.688-698
• /
• 2020

Point clouds have ability to express the spatial entities, however, the point clouds redundancy always involves some uncertainties in computer recognition and model construction. Therefore, point clouds thinning is an indispensable step in point clouds model reconstruction and other applications. To overcome the shortcomings of complex classification index and long time consuming in existing point clouds thinning algorithms, this paper proposes a point clouds fast thinning algorithm. Specifically, the two-dimensional index is established in plane linear array (x, y) for the scanned point clouds, and the thresholds of adjacent point distance difference and height difference are employed to further delete or retain the selected sample point. Sequentially, the index of sample point is traversed forwardly and backwardly until the process of point clouds thinning is completed. The results suggest that the proposed new algorithm can be applied to different targets when the thresholds are built in advance. Besides, the new method also performs superiority in time consuming, modelling accuracy and feature retention by comparing with octree thinning algorithm.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2016년도 전력전자학술대회 논문집
• /
• pp.469-470
• /
• 2016

Since efficiency of maximum power point tracking (MPPT) is important for photovoltaic systems, a number of MPPT algorithms have already been researched for other environment, however, the most of MPPT algorithms can't track maximum point in dynamic irradiation. In this paper, P&O and 3-Point MPPT which is more specialized in dynamic irradiation are compared in basis of European Efficiency Test(EN50530). The efficiency of 3-Point MPPT algorithm is proved by simulation and experiment. In result, 3-Point MPPT shows higher efficiency in dynamic irradiation and less affected by environment than P&O.

• 대한방사선치료학회지
• /
• 제24권2호
• /
• pp.61-66
• /
• 2012

목 적: 본 연구에서는 자궁강 내 근접치료 시 ABS (American Brachytherapy Society)에서 권고한 H점(point H)을 이용한 치료계획을 수립해 보았고, 이를 A점(point A)에 처방한 치료계획과 비교하고자 한다. 대상 및 방법: 2010년 3월부터 2012년 1월까지 본원에 내원한 자궁경부암 환자 중 탄뎀(tandem)과 난형체(ovoid)를 이용해 고선량률 강내 근접치료(high dose rate intracavitary brachytherapy)를 시행한 103명을 대상으로 하였다. 치료계획은 Manchester System에 따라 A점, 방광 기준점, 직장 기준점을 지정하였고, ABS의 권고에 따라 H점을 지정하였다. 또한 임의로 S자 결장기준점과 질 기준점을 설정하였다. A점과 H점의 위치가 얼마나 차이가 나는지 살펴보았으며, H점에 100%의 선량을 처방하였을 때 A점에 들어가는 선량을 계산하였다. 그리고 A점과 H점에 각각 선량을 처방하였을 때 직장, 방광, S자 결장, 질 기준점에 들어가는 선량을 비교 분석하였다. 결 과: H점이 A점보다 미측에 있는 경우 A점의 상대선량은 기존의 A점이 아닌 H점에 처방하였을 때 더 적어지는 경향을 보였다. 방광 기준점과 직장 기준점, S자결장 기준점, 질 기준점에서의 상대선량은 H점이 두측에 있는 경우 H점에 처방하였을때의 선량이 A점에 처방하였을 때보다 크며, 미측에 있는 경우 더 적어지는 양상을 보였다. 결 론: H점이 A점보다 두측에 위치할수록 주변 장기의 흡수선량이 커지고, 미측에 위치할수록 주변 장기의 흡수선량이 적어지는 경향을 보였다. 그 선량 차이가 치료에 큰 영향을 미칠 정도는 아니지만, 두 치료계획에서의 선량 분포 및 주변 장기 흡수선량 차이가 크다면 두 점의 치료계획은 비교 또는 참고할 만한 가치가 있는 것으로 생각된다.

• 전력전자학회논문지
• /
• 제19권5호
• /
• pp.407-414
• /
• 2014

This study proposes a control design for the grid output current and for reducing the neutral-point voltage oscillation through the small-signal modeling of the three-phase grid connected with a three-level neutral-point-clamped (NPC) inverter with LCL filter. The three-level NPC inverter presents an inherent problem: the neutral-point voltage fluctuation caused by the neutral-point current flowing in or out from the neutral point. The small signal modeling consists of averaging, dq0 transformation, perturbing, and linearizing steps performed on a three-phase grid connected to a three-level NPC inverter with LCL filter. The proposed method controls both the grid output and neutral-point currents at every switching period and reduces the neutral-point voltage oscillation. The validity of the proposed method is verified through simulation and experiment.

• Journal of Power Electronics
• /
• 제16권6호
• /
• pp.2109-2118
• /
• 2016

Based on the space vector pulse width modulation (SVPWM) theory, this paper realizes an easier SVPWM strategy, which is equivalently implemented by CBSPWM with zero-sequence voltage injection. The traditional SVPWM strategy has no effect on controlling the neutral-point voltage balance. In order to solve the neutral-point voltage unbalance problem for neutral-point-clamped (NPC) three-level inverters, this paper proposes a neutral-point voltage balance controller. The proposed controller realizes controlling the neutral-point voltage balance by dynamically calculating the offset superimposed to the three-phase modulation waves of an equivalent SVPWM strategy. Compared with the traditional SVPWM strategy, the proposed neutral-point voltage balance controller has a strong ability to balance the neutral-point voltage, has good steady-state performance, improves the output waveforms quality and is easy for digital implementation. An experiment has been carried out on a NPC three-level inverter prototype based on a digital signal processor-complex programmable logic device (DSP-CPLD). The obtained experimental results verify the effectiveness of the proposed neutral-point voltage balance controller.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 춘계종합학술대회
• /
• pp.705-708
• /
• 2005

본 연구에서는 점대점(point-to-point) 링크상에서 각 스테이션 간의 안테나 빔의 스위트 스폿을 찾고 유지하는 방법을 제안 한다. 제안한 방식은 송수신 데이터에 안테나의 정보를 같이 실어 보내고 그 정보를 이용하여 신경회로망 중에서 간단한 두개의 ADALINE으로 스위트 스폿을 찾고 유지 한다. 통신방식은 시분할 이중화 방식으로 하고, 두개의 ADALINE을 병렬로 연결하여 원하는 목표값에 수렴하고 유지한다. 제안한 방식의 유용성을 점대점(Point-to-Point) 링크상에서 잡음이 없는 경우와 잡음이 첨가된 경우에 대하여 시뮬레이션을 통하여 확인하였다