Delta변조 및 Adaptive delta변조의 잡음원인에 관한 해석과 비교연구

정구철 중앙대학교 1987 硏究論集 Vol.6 No.1

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.

청소년들의 부모애착이 학습몰입에 미치는 영향: 부모의 학업기대와 낙관성의 매개효과

정구철,설미경 한국융합학회 2019 한국융합학회논문지 Vol.10 No.7

The purpose of this study was to analyze the mediating effects of parental academic expectations and adolescent’s optimism in the influence of perceived parental attachment on learning flow. The subjects of this study were 184 middle and high school students in Seoul. The results of this study are as follows. First, academic expectation and optimism showed significant full mediation effects on the relationship between parent attachment and learning flow. Second, there was no statistically significant difference in the difference between the indirect effects of academic expectation and optimism by the bootstrapping method. Based on the results of this study, it was found that the healthy attachment relationship with the parents increases the parent's supportive expectancy, improves the optimism for the youth, and improves the learning commitment for effective learning. Finally, we discussed the role and expectations of parents and adolescents in promoting the learning commitment of adolescents. 본 연구는 청소년들이 지각한 부모애착이 학습몰입에 미치는 영향에서 부모의 지지적 학업기대와 청소년의 낙관성의 매개효과를 융합적으로 검증하고자 수행되었다. 연구 대상은 서울특별시에 소재한 중·고등학교 학생 184명이었다. 연구결과, 첫째, 학업기대와 낙관성은 부모애착과 학습몰입 간의 관계에서 완전 매개효과를 보였다. 간접효과의 유의성을 Bootstrapping 방법으로 분석한 결과, 부모의 학업기대와 청소년의 낙관성을 통한 간접효과는 모두 통계적으로 유의하였다. 둘째, 학업기대와 낙관성의 간접효과 간의 차이를 Bootstrapping 방법으로 분석한 결과 통계적으로 유의한 차이가 없었다. 이러한 연구 결과를 바탕으로 부모와의 건강한 애착 관계는 부모의 지지적 기대를 증가시키고, 청소년들에게는 낙관성을 증진시켜, 효율적인 학습을 위한 학습몰입을 향상시키는 것을 알 수 있었다. 그리고, 청소년의 학습몰입을 증진시키기 위한 부모와 자녀의 역할과 기대에 대해 논의하였다.

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.

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.

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.

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.

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.

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.

교회 갈등이 교회 헌신도에 미치는 영향: 대인신뢰의 매개효과

정구철,이건호,Jeong, Goo-Churl,Lee, Kun-Ho 한국융합학회 2020 한국융합학회논문지 Vol.11 No.9

본 연구는 기독교인들을 대상으로 교회 내 갈등이 교회헌신도에 미치는 영향에서 대인신뢰의 매개효과를 검증하기 위해 수행하였다. 본 연구를 위해 설문조사법으로 기독교 성인 218명의 자료를 수집하였다. 연구결과, 첫째, 교회 내 갈등은 대인신뢰와 유의한 부적 상관관계가 있었다. 둘째, 교회 내 갈등은 교회헌신도와 유의한 부적 상관관계가 있었다. 셋째, 기독교인의 교회 내 갈등이 교회헌신도에 미치는 영향에서 교인에 대한 인지적 신뢰가 유의한 매개효과를 보였다. 넷째, 기독교인의 교회 내 갈등이 교회헌신도에 미치는 영향에서 목사에 대한 정서적 신뢰가 유의한 매개효과를 보였다. 이러한 연구결과를 바탕으로 교회 내에서 발생하는 갈등을 관리하기 위해 목사에 대해서는 정서에 기반한 신뢰 관계 형성이 중요하고, 동료 교인에 대해서는 인지에 기반한 신뢰 관계 형성의 중요성을 논의하였으며, 갈등을 예방하기 위한 교회 조직구성원의 역할에 대해 제언하였다. This study aims to examine the mediating effect of interpersonal trust on the effect of church conflict on church commitment. For this purpose, a survey was conducted on 218 christian adults. First, it was revealed that church conflict had a significant negative correlation with interpersonal trust. Second, church conflict had a significant negative correlation with church commitment. Third, the cognitive-based trust of church members showed a significant mediating effect on the effect of christian conflict on church commitment. Fourth, pastor's emotion-based trust had a significant mediating effect on the effect of christian conflict on church commitment. Based on these findings, we discussed the importance of trust based on pastor's sentiment and trust based on the recognition of fellow church members to manage church conflicts.