차량통신기술의 현재와 미래

조웅,오현서 한국자동차공학회 2011 한국자동차공학회 Workshop Vol.2011 No.1

섀도우드 라이시안채널에서 CDMA를 이용한 저궤도 위성시스템의 성능 ( Performance of CDMA-Based LEO Satellite Systems in a Shadowed Rician Channel )

조웅,박상규 한국통신학회 1998 한국통신학회 학술대회논문집 Vol.17 No.3

비편평화여과기 방사선 빔을 위한 분석적 빔 소스 모델 개발

조웅,Kayla N. Kielar,Ed Mok,박정훈,정원균,서태석 대한방사선방어학회 2011 대한방사선방어학회 학술발표회 논문요약집 Vol.2011 No.04

Dosimetric Effects on Small-field Beam-modeling for Stereotactic Body Radiation Therapy

조웅,김수지,김정인,우홍균,정주영,김민주,서태석,김진영,김종원 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.4

The treatment planning of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy(SBRT) requires high accuracy of dosimetric data for small radiation fields. The dosimetriceffects on the beam-modeling process of a treatment planning system (TPS) were investigated usingdifferent measured small-field data sets. We performed small-field dosimetry with three detectors:a CC13 ion chamber, a CC01 ion chamber, and an edge detector. Percentage depth doses (PDDs)and dose profiles for field sizes given by 3 × 3 cm2 , 2 × 2 cm2 , and 1 × 1 cm2 were obtainedfor 6 MV and 15 MV photon beams. Each measured data set was used as data input for a TPS,in which a beam-modeling process was implemented using the collapsed cone convolution (CCC)algorithm for dose calculation. The measured data were used to generate six beam-models basedon each combination of detector type and photon energy, which were then used to calculate the correspondingPDDs and dose profiles for various depths and field sizes. Root mean square differences(RMSDs) between the calculated and the measured doses were evaluated for the PDDs and the doseprofiles. The RMSDs of PDDs beyond the maximum dose depth were within an accuracy of 0.2 −0.6%, being clinically acceptable. The RMSDs of the dose profiles corresponding to the CC13, theCC01, and the edge detector were 2.80%, 1.49%, and 1.46% for a beam energy of 6 MV and 2.34%,1.15%, and 1.44% for a beam energy of 15 MV, respectively. The calculated results for the CC13ion chamber showed the most discrepancy compared to the measured data, due to the relativelylarge sensitive volume of this detector. However, the calculated dose profiles for the detectors werenot significantly different from another. The physical algorithm used in the beam-modeling processdid not seem to be sensitive to blurred data measured with detectors with large sensitive volumes. Each beam-model was used to clinically evaluate lung and lymphatic node SBRT plans, yieldingalmost equal dose distributions for the treatment targets, while the mean doses related to the organsat risk (OARs) deviated by approximately 0.7 − 1.2%. The use of the measured data sets fromdifferent detectors for the beam-modeling process still provided acceptable dose distributions withaccuracies within 2%.

여성의 농촌관광 만족과 재방문에 관한 연구

조웅,정용악 한국관광산업학회 2012 Tourism Research Vol.37 No.-

People often travels in a family unit and for such a modern-day society family, those who make a decision is not one but 'mom'. With varied types of travel that each family takes by children age, those families with their kids prefer hands-on experience program, in which case the farmland travel marketing counts and marketing strategy for a decision-making mom will be crucial. According to the study's analysis upon what motivated families to participate in the farmland travel, most of women feel and become aware of their 'ego' when visiting farmland, while taking 'rural atmosphere' into account when visiting again. That women struggle with their urban life and sacrifice their own lives in the name of 'housewife' by putting the familial value first appears to contribute to such results, which signify the direction of farmland travel should chase after, the ego-finding, self-developing, and life-recharging experiences for hectic women. Agin, taking rural atmosphere into account, it is also significant to emphasize the regional peculiarity, environment-friendliness, and village-unit travel system, as well as keeping the natural, cultural, and region-specific values without mere imitation of just another travel packages and villages. What is important here is keeping and developing the conventional value that our ancestors have kept and reflecting such into modern-day travel programs involving hands-on experiences.

Practical Implementation of a Collapsed Cone Convolution Algorithm for a Radiation Treatment Planning System

조웅,서태석,박정훈,Lei Xing,이정우 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.12

A collapsed cone convolution algorithm was applied to a treatment planning system for the calculation of dose distributions. The distribution of beam fluences was determined using a three-source model by considering the source strengths of the primary beam, the scattered beam from the primary collimators, and an extra scattered beam from extra structures in the gantry head of the radiotherapy treatment machine. The distribution of the total energy released in media (TERMA) was calculated from the distribution of the fluence by considering several physical effects such as the polyenergetic photon spectra, attenuation of beam fluence in a medium, horn effect, beam-softening effect, and beam transmission through collimators or multi-leaf collimators. The distribution of the doses was calculated by the convolution of the distribution of TERMA and the polyenergetic kernel. The distribution of the kernel was approximated to several tens of collapsed cone lines to express the energies transferred by electrons that originate from the interactions between the photons and the medium. The implemented algorithm was validated by comparing the calculated percentage depth doses (PDD) and dose profiles with the measured PDDs and relevant profiles. In addition, the dose distribution for an irregular-shaped radiation field was verified by comparing the calculated doses with the measured doses obtained via EDR2 film dosimetry and the calculated doses obtained using a different treatment planning system based on the pencil beam algorithm (Eclipse, Varian, Palo Alto, USA). The majority of calculated doses for PDDs, profiles, and the irregular-shaped field showed good agreement with the measured doses within 2% of dose difference, except in the build-up regions. The implemented algorithm was proven to be efficient and accurate for clinical purposes in radiation therapy, and it was found to be easily implementable in treatment planning systems.

도심 차량통신환경에서의 전파특성 측정과 구현 이슈

조웅,Cho, Woong 한국전자통신학회 2014 한국전자통신학회 논문지 Vol.9 No.9

차량통신시스템은 차량/도로기술과 정보통신기술을 접목하여 다양한 안전메시지를 전송하거나 지능형 교통시스템에 적용이 가능하다. 본 논문에서는 IEEE 802.11p를 기반으로 한 차량통신시스템을 소개하고 이 시스템의 전파특성을 도심환경에서 측정한 결과를 보인다. 전파특성은 패킷오류율과 수신스펙트럼을 이용하여 측정한다. 이 결과를 바탕으로 하여 실제 서비스 적용에 있어서 필요한 구현 이슈에 대해 논의한다. Vehicular communications can be applied for transmission of various safety messages or Intelligent Transportation Systems(ITS) applications by combining vehicle/road technology with Information and Communication Technology(ICT). In this paper, we represent measurement results of radio characteristics of vehicular communications using IEEE 802.11p based system in urban environments. Radio characteristics are based on the packet error rate (PER) and received spectrum mask. Using measurement results, we discuss implementation issues of vehicular communication systems for supporting reliable services.

차량통신에서의 물리계층 이슈

조웅,Cho, Woong 한국전자통신학회 2012 한국전자통신학회 논문지 Vol.7 No.5

차량통신은 통신시스템과 차량산업을 융합하여 ITS (Intelligent Transport Systems)분야에서 다양한 서비스 제공을 위해 고려되어져 왔다. 일반적으로 차량통신은 WAVE (Wireless Access in Vehicular Environments)라고 알려져 있는 IEEE 802.11p/1609표준을 채택하여 차량간 통신 및 차량-노변기지국간 통신에 이용된다. WAVE 시스템은 OFDM (Orthogonal Frequency Division Multiplexing) 신호를 5.9GHz대의 주파수를 사용하여 신호를 전송하는 시스템이다. 본 논문에서는 차량통신 영역 중 물리계층의 이슈들에 관하여 논의한다. 먼저 WAVE 표준의 물리계층과 5.9GHz대의 신호의 특성에 대해 살펴본 후 신뢰성 있는 통신링크 제공을 위해 물리계층에서 개선되어야할 점에 대해 논의한다. Vehicular communications have been receiving much attention in intelligent transport systems (ITS) by combining communication technology with automobile industries. In general, vehicular communications can be used for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication by adopting IEEE802.11p/1609 standard which is commonly known as wireless access in vehicular environments (WAVE). WAVE system transmits signal in 5.9GHz frequency band with orthogonal frequency division multiplexing (OFDM) signaling. In this paper, we consider physical layer issues in vehicular communications. We first overview the physical (PHY) layer of WAVE standard and properties of 5.9GHz signals, and then physical layer issues to provide reliable communication link are discussed.

상충지역에서 고령 보행자를 위한 안전메시지 전송기술 : 배경 및 기술 개념

조웅,장정아,Cho, Woong,Jang, Jeong-Ah 한국전자통신학회 2015 한국전자통신학회 논문지 Vol.10 No.3

고령화의 증가에 따라 고령자의 교통사고가 사회적으로 이슈가 되고 있다. 본 논문에서는 고령자의 교통사고 현황을 분석하고, 분석된 자료를 기반으로 하여 보행 고령자를 위한 안전메시지 전송기술에 대해 소개한다. 제안하는 안전메시지 전송기술은 정보통신기술을 차량과 고령자에 접목한 차량-보행자간 통신기술에 기반을 두고 있다. 제안하는 전송기술의 개념의 동작원리에 대해 소개하고 제안하는 시스템을 구현하기 위해 필요한 사항들에 대해 논의한다. As the elderly are increasing, traffic accidents which are related to the elderly are one of major issues in aged society. In this paper, we analyze traffic accident statistics for the elderly. Based on the analyzed data, safety message transmission system for the elderly pedestrians is introduced. The proposed system is based on the P2V(Pedestrian-to-Vehicle) communication which combines ICT(Information and Communication Technology) with vehicles and pedestrians. We introduce the concept and principle of the proposed system and discuss implementation issues for realizing the proposed system.

차량통신환경에서의 자동이득제어기법 적용

조웅,오현서 한국ITS학회 2011 한국ITS학회논문지 Vol.10 No.4

무선통신환경에서는 RF신호가 매우 심하게 변하는데, 이러한 신호의 변화는 특히 차량통신환경에서 더욱 심해진다. 자동이득제어는 무선통신시스템에서 신뢰성 있는 통신환경을 제공하고 급격하게 변하는 수신신호를 보상하데 중요한 역할을 한다. 본 논문에서는 수신신호세기값과 아날로그-디지털변환값 두 가지 신호를 이용하는 간단하고 향상된 자동이득제어기법에 대해 논의한다. 시물레이션과 실제 환경에의 측정을 통해 제안된 기법의 성능을 검증한다. Radio Frequency (RF) signal fluctuates dynamically in wireless communication environments, where this fluctuation is severe especially in vehicular environments. Automatic Gain Control (AGC) is critical in wireless communications to establish reliable communication links and compensate the received signal fluctuation. In this paper, we introduce a simple and novel AGC scheme which uses both Received Signal Strength Indicator (RSSI) and analog-to digital converter (ADC) signals. Performance enhancement of the proposed AGC scheme is verified with practical measurements including simulations.