DSRC를 이용한 자동게이트통관시스템의 성능분석

정동영,박상완,정봉식 동아대학교 정보기술연구소 2001 情報通信硏究所論文誌 Vol.9 No.1

The performance and characteristics of automatic gate clearance system(AGS) developed for automatizing gate clearance to container vehicles at the gate of container terminal are analyzed. The AGS exchanges vehicle and container informations by wireless communication between roadside equipment(RSE) and onboard equipment(OBE) using DSRC(Dedicated Short Range Communication) system operated at 5.8GHz ISM(Industrial Scientific Medical) band. We found that this system had better performance than conventional systems, such as barcode system and camera recognition system, through many experiments and field tests.

유한요소법과 흡수경계조건을 이용한 산란파 해석

정봉식 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.1

The finite element method with absorbing boundary condition for open boundary problems like as 2-dimensional infinitely long inhomogeneous circular or rectangular dielectric scatterer is presented. High order boundary condition (absorbing boundary condition), which is able to put on an approximate extenal boundary near the scatterer, are used to reduce number of unknown and computation time. Homogeneous circular scatterer of the radius of 0.3λ and homogenous rectangular scatterer of 1.0λ×1.0λ in the free space are considered. The relative permittivity of homogenous scatterer is 2.0. The relative permittitivities of an inhomogenous rectangular scatterer are 2.0 in the cross-section of 1.0λ×1.0λ and 4.0 in 0.5λ×0.5λ. The accuracy of scattered fields is investigated as the element size and the radius of approximate extenal boundary are decreased. Numerical results calculated by a quadratic(2nd order) basis function compared with by a linear (1st order) one are well agreed with an analytic solution.

요한요소법과 LMA-GA 혼합법을 이용한 거대 강산란체의 역산란

정봉식 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.2

An iterative inverse scattering method(IISM) for reconstructing the permittivity of two dimensional high contrast and large object is presented. This method uses the finite element method(FEM) for calculating the scattering fields and the hybrid method for minimizing the cost function. The FEM calculates the scattered fields faster than the method of moment(MM). The hybrid method(HLMGA) is composed of a Levenberg-Marquardt algorithm(LMA) and a genetic algorithm(GA). Numerical results show that the IISM based on the HLMGA and GA can always reconstruct all the permittivity profiles of a high contrast and large object, in contrast the IISM based on the LMA often converges to the local minima of the cost function. The HLMGA gives better permittivity profiles and faster convergence than the GA. When the noise is presented in the scattering fields, the characteristics of the cost function show that multiple incident waves are needed for the stable inversion. Also both LMA and a prior knowledge of background medium for a fast convergence are used. The permittivity profile converged to local minima by LMA is modified by substituting the background profile into a known background medium, then this modified profile as an initial one in order to get out of a local minima of cost function is used.

유한요소법에 의한 도파관 급전 캐비티의 전자계해석

정봉식,안창회 嶺南大學校 工業技術硏究所 1994 工業技術硏究所論文集 Vol.22 No.2

Electromagnetic fields of the rectangular waveguide-loaded cavity are calculated using finite element method. Magnetic field vectors are used as vector variables with edge basis functions. The cavity analyzed in this paper is loaded by the rectangular waveguide only ?? mode excited. Also complex reflection coefficients are obtained.

동축선로형 λ/4초크 대역억제필터의 최적화

정봉식,이규한,김진길 東亞大學校 附設 情報通信硏究所 1999 情報通信硏究所論文誌 Vol.7 No.1

In this paper the band-stop filter that rejects the undesired 3th and 5th harmonics generated from high frequench generator is analyzed and optimized. The length of the band-stop filter is setup initially a quarter of a wavelength fo the harmonic, but initial filter structure is unable to cutoff the harmonics because of the fringing effect at the input of the choke. To reduce the mismatch between the cutoff frequency and the harmonics, the length of the choke is optimized by using iterative Levenberg-Marquardt Algorithm.

구개측으로 매복된 상악견치의 교정치료기간에 영향을 미치는 요소

정송화,김성식,조봉혜 대한치과교정학회 2007 대한치과교정학회지 Vol.37 No.2

구개측으로 매복된 견치와 인접구조물 간의 위치관계가 전체적인 교정치료기간에 어떤 영향을 미치는지 알아보고자 편측성 구개측 견치 매복으로 진단받고, 교정적인 견인을 하여 치료를 완료한 환자 36명의 초진 시 파노라마 방사선사진을 대상으로 연구하였다. 전체 치료기간의 평균인 21개월을 기준으로 나누었을 때, 장기치료군에 비해 단기치료군에서 인접 측절치의 치근에 견치의 치관이 겹치는 정도가 더 크게 나타났다. 치료기간을 예측하기 위한 중회귀분석에서 상악견치의 치관에서 치조정까지의 교합면에 대한 수직거리를 나타내는 HCV (Height of the canine crown vertically)와 하악견치간폭경이 각각 0.142와 0.115의 예측상수(r2)를 보였으며, 두 인자를 같이 고려하였을 경우에는 0.208의 예측상수를 보였다. 나이에 따른 분류에서 치료기간, 상악 견치 치관에서 치조정까지의 수직거리 (HCV), 중절치 정중선에 대한 견치의 각도가 초기 영구치열기까지는 점진적으로 감소를 하다가 완성 영구치열기에서 증가하였다. 본 연구의 결과, 구개측으로 매복된 견치의 견인을 시행할 때에는 초기 영구치열기에 견치의 치관첨이 교합면에 가깝고 직립이 되어 있을 경우에 전체 교정치료 기간이 짧아진다는 것을 알 수 있었다. Objective: The aim of this study was to determine the relationship between the status of a unilateral palatally impacted maxillary canine (as seen on the panoramic radiograph) and the orthodontic treatment duration. Methods: A total of 36 subjects were chosen (8 males and 28 females, 13.7 ± 2.5 years). All patients had undergone orthodontic traction of the impacted canine after a closed flap surgery. The position of impacted canine on the panoramic radiograph was traced and calculated with regard to the treatment duration. Results: The canine overlap over the lateral incisor (COGr) had significant statistical difference between the short-term and the long-term treatment duration groups (divided by average treatment time of 21 months) (p < 0.05). Multiple regression indicated that the variables of significance (with treatment duration as the dependent variable) were the canine vertical height from the occlusal plane (HCV, r2 = 0.115; p < 0.05) and the mandibular anterior width (MnDW, r2 = 0.142; p < 0.05). The treatment duration, the canine angle to the incisor midline (CA), and HCV decreased from primary dentition (under 12 yrs) to permanent dentition (15 yrs). Howerer, these increased again at the adolescent ages (over 16 yrs). Conclusion: These findings suggested that orthodontic treatment of a palatally impacted canine would show good prognosis at an age of early permanent dentition with the canine showing smaller CA and HCV.

소형 개구면 결합 원형분극 마이크로스트립 배열안테나

황인진,정봉식 東亞大學校附設情報技術硏究所 2005 情報技術硏究所論文誌 Vol.12 No.2

In this paper the compactness of aperture-coupled array antenna with CP(circularly polarized) radiation for 2.4GHz wireless communication hand-set is designed. the compact operation of microstrip antenna is obtained by inserting suitable slits in the radiating patch, and CP radiation by perturbing the diagonal corners in the radiating patch, which generates the resonant mode of interest into two nearly degerate modes. Feed network of array antenna is made by using a two-layer and aperture-coupled structure. By numerical and experimental results, the patch size of compact CP micro strip antenna is reduced about 37% than conventional one without compact technique.

연령증가에 따른 생쥐 혈액-가슴샘 관문의 미세구조

안의태,최석봉,고정식,경홍기,한영복 대한해부학회 1994 Anatomy & Cell Biology Vol.27 No.4

스마트 키 리더기용 PIFA형 315MHz 스파이럴 안테나 설계

오동준,정봉식 동아대학교 정보기술연구소 2007 情報技術硏究所論文誌 Vol.14 No.2

In this paper, PIFA(Planar Inverted-F Antenna)-type 315MHz spiral antenna for smart key ECU(Electronic Control Unit) is designed. PIFA-type structure gives easy impedance matching and antenna size reduction effect. The frequency fluctuations caused by the circuits on the PCB and the smart key ECU case have to be considered to design antenna. Antenna specifications are the center frequency of 315MHz, 10dB bandwidth of 3MHz, omni-directional radiation pattern, and antenna size of 30mm by 20mm on the PCB. we find that the measurement results are agreed to the simulation results and the smart key reader with the designed antenna is well operated in the outdoor environment.

MUSIC 알고리즘용 고유치 분해법의 하드웨어 구현

박병우,정봉식,변건식 東亞大學校附設 淸報技術硏究所 2006 情報技術硏究所論文誌 Vol.13 No.2

This paper describes the hardware implementation of the EVD (Eigenvalue Decomposition) method for MUSIC algorithm. MUSIC algorithm is one of the super resolution algorithm which can estimated DOA. Applying isomorphic transformation, this system can be formulated in terms of real-valued computation. And using the householder matrix, we could reduce the burden of computation to evaluate the eigenvalue decomposition. Results show that eigenvalues have error rates within 0.7% in Matlab and VHDL simulation. The unique features of this system are the fast and compact computation of EVD.