Delta변조 및 Adaptive delta변조의 잡음원인에 관한 해석과 비교연구

정구철 중앙대학교 1987 硏究論集 Vol.6 No.1

누설 동축 케이블의 입력 임피던스 및 전류 분포 해석

정구철 한국기술교육대학교 1998 論文集 Vol.5 No.1

The satellite communication systems, land mobile communication systems, vehicular systems, and in indoor radio systems a very important problem is that of maintaining stable communications at all locations. Therefore solutions for the free apace and indoor propagation problem are an important aspects of the mobile communication systems. Generally leaky coaxial cables are finding increasing use in electromagnetic wave transmission systems involving mines, tunnels, railroads, and highways and in new obstacle detection, or guided radar, schemes for ground transportation and perimeter surveillance. In this paper a leaky coaxial cable with periodic slots in the outer conductor is described to obtain the propagation modes in the various environments. We use an eccentric cylindrical model to develop the theory for surface-wave propagation on the leaky coaxial cable. Numerical results are also included for the impedance as function of various parameters and current distribution. The above calculations for leaky coaxial cable are shown to agree closely with derived the electromagnetic equation.

논문집 : 제주월드컵 경기장의 효과적인 사후활용방안에 대한 논의

정구철 제주대학교 체육과학연구소 2002 체육과학연구 Vol.8 No.-

DS/CDMA 방식을 적용한 무선 LAN의 성능에 관한 연구

정구철 韓國技術敎育大學校 1996 論文集 Vol.3 No.1

In this paper, a performance analysis is carried out for a Direct-Sequence Code Division Multiple Access(DS/CDMA) system in a star-connected slotted wireless network. The system is described by a discrete time Markov chain model for a finite number of simultaneous users. Steady state results for throughput vs. offered loads and the delay vs. throughput are obtained from a simulation model developed with poison arrival assumption. It has been shown that, like the familiar ALOHA channel, random access CDMA channels degrade rapidly when loaded beyond a certain point and that the steady state delay is at its smallest value with a highest value or retransmission probability Pr. CDMA systems with best with best performance may be designed on the model developed by choosing optimal values for Pr and Po, initial transmission probability, based on traffic characteristics.

잘린 환형 산란체에 유도되는 전류 밀도 해석

정구철 한국기술교육대학교 2000 論文集 Vol.7 No.1

In the study of antenna theory, a knowledge of the current distribution is of fundamental importance. Such data may be obtained either by measurement or by solving the antenna integral equation. Integral equations are difficult to solve even for the simplest case of a dipole antenna. However powerful computer enable the use of integral equation method in larger range. The use of high speed digital computers not only allows more computational power, but it makes practicable methods of solving repetitive calculation. In this paper cleaved circular scatterers fed by coaxial cable is described to obtain current density in the various environments. To illustrate the use of presented formulation method of integral equations it is applied to the cleaved circular scatterers. Also, the current density induced by an incident plane wave illumination are obtained for the cleaved circular scatterers. Results obtained are very close to Taylor's results of cylindrical antenna.

잘린 환 안테나의 복사 패턴 해석

정구철 한국기술교육대학교 1999 論文集 Vol.6 No.1

In conventional formulation of antenna problem, an integral equation for the antenna current distribution is derived by forcing the component of the scattered electric field tangential to the antenna surface to cancel the corresponding of the incident field over the antenna surface. To solve the scattering problem an integral equation is derived for the total axial current distribution induced under arbitrary illumination. As to the transmitting antenna problem the integral equation is derived for the frill excitation. Formally the integral equations mentioned above can be applied only the bodies with no discontinues in radius. When discontinues occur as in the case of cleaved circular antenna with flat end faces, an approximate technique is used that in general is quite accurate for the relatively thin antenna. In this paper cleaved circular antenna fed by coaxial cable is described to obtain radiation pattern in the various environments. To illustrate the use of presented formulation method of integral equations it is applied to the cleaved circular antenna. Pure linear integral equations is derived with extended boundary conditions are derived and the effect of end face is calculated using quasi static approximation method. The above calculations for cleaved circular antenna are very closely with derived the electromagnetic equation.

PON에 의한 FTTC 구성 방안 고찰

정구철 한국기술교육대학교 1994 論文集 Vol.1 No.1

In this paper, constructional scheme(SS, ADS, PDS) of Fiver To The Curb are described and the optimized schme of PON components such as optical fiber and power splitter to build an cost-effective FTIC configuration is considered PON type of FTTC configration is cost-effective as compared with ADS or SS type, also it is easy to form optical cableling of subscriber network relatively. However, there is small effects on economy according to N size in the case that RT(ONU) are large capacity, therefore PIP connection has advantages in considering of upgrade while PON type effects in the case that RT are small capacity. And get the reasonable N=16, the number of access fiber is 2, and the location of splitters is 0.5-0.6 Lt affects both the economy and upgrade costs so as to optimized schme of PON type.

진행파형 전계흡수 변조기의 비선형 모델에 관한 연구

정구철 한국기술교육대학교 2006 論文集 Vol.12 No.1

In this paper, we introduce a novel model to analyze the linearity of a TW-EAM (traveling-wave electroabsorption modulator). The device length, microwave loss (ML), and internal reflection (IR) due to impedance mismatch have effect on the linearity of a TW-EAM. The longer devices have characteristics of lower biases with minimum IMDs (intermodulation distortions). ML decreases the output power as well as the IMD value. Internal reflection has different nonlinear characteristics according to the wavelength of the input frequency and the device length. There is little change in SFDR (spurious-free dynamic range) due to ML or IR. As a result, for a 50 GHz band RF-optical communication system, a 0.8 mm-long TW-EAM with the lowest ML would have better properties by using IR, which is caused by impedance, mismatch at the output port.

주기적 슬롯을 가진 누설 동축 케이블의 필드 분포에 관한 연구

정구철 한국기술교육대학교 1997 論文集 Vol.4 No.1

In indoor radio systems, vehicular communication systems, and land mobile systems, a very important problem is that of maintaing stable communications at all locations. Therefore solutions for the indoor propagation problem are an important aspects of the mobile communication system. Leaky coaxial cables are finding incresing use in communication systems involving mines, tunnels, railroad, and highways or guided radar, schemes for ground transportation and perimeter surveilance. In this paper a leaky coaxial cable having periodic slots in the outer conductor is described to obtain the propagation modes and the various environments. We use an eccentric cylindrical model to develop the theory for surface-wave propagation on the cable.

대학생들의 건강증진생활양식이 주관적 웰빙에 미치는 영향: 정신건강의 매개효과

정구철,주지향 한국융합학회 2019 한국융합학회논문지 Vol.10 No.8

The purpose of this study was to analyze the mediating effect of mental health on the relationship between health promotion lifestyle and subjective well-being of college students. The study subjects were 282 college students. Data were analyzed by ANOVA, correlation analysis and multiple regression analysis. Results, first, the health promoting lifestyle has a significant positive effect on subjective well-being. Second, the health promotion lifestyle had significant negative impact on mental health. Third, the variables of depression, psychopathic deviate, paranoia, psychasthenia, schizophrenia were significant mediating parameters in the relationship between health promotion lifestyle and subjective well-being. Based on these results, we discussed the importance of health promoting behaviors for mental health and happiness of college students. 본 연구의 목적은 대학생들의 건강증진생활양식과 주관적 웰빙 간의 관계에서 정신건강의 매개효과를 분석하는 것이다. 연구대상은 대학생 283명이었다. 자료의 분석은 분산분석, 상관관계분석 및 회귀분석을 사용하였다. 연구결과, 첫째, 대학생들의 건강증진생활양식은 주관적 웰빙에 유의한 정적 영향을 미치는 것으로 나타났다. 둘째, 건강증진생활양식은 정신건강에 유의한 부적 영향을 미치고 있었다. 셋째, 대학생들의 건강증진생활양식과 주관적 웰빙 간의 관계에서 정신건강의 우울증, 반사회성, 편집증, 강박증, 정신분열증의 변수들이 유의한 매개변수로 나타났다. 이러한 연구결과를 바탕으로 대학생들의 행복 증진과 정신건강을 위한 건강증진행위의 중요성을 논의하였다.