농약을 먹고 살수야 없지 않는가?

정홍식,Jeong, Hong-Sik 한국건강관리협회 1991 건강소식 Vol.15 No.9

진행파형 Ti : LiNbO3 위상 광변조기 제작 ( Fabrication of Traveling-wave Ti : LiNbO3 Phase Optical Modulators )

정홍식,엄진섭,김원옥 대한전자공학회 1993 대한전자공학회 학술대회 Vol.1993 No.1

진행파형 Ti:LiNbO$_3$위상 광변조기 설계 및 제작에 관한 연구

정홍식,서정하,엄진섭 한국통신학회 1994 韓國通信學會論文誌 Vol.19 No.9

$Ti:LiNbO_3$채널형 광도파로와 Asymmetric Coplanar Strip(ACPS) 전극구조를 이용해서, $1.3{\mu}m$에서 동작하는 진형파형 위상 광변조기를 설계, 제작한 다음 변조특성을 관찰하였다. 위상정합이 개선되도록 ACPS 진행파형 전극을 설계하기 위해서 전극과 완충박막의 두께를 포함하여, 전극제원의 해석적 함수로 특성저항, 변조파의 유효굴절률 및 전극손실 등을 고려하였다. Ti 확산방법으로 저손실 채널형 광도파로 제작하였으며, double-spin image reversal 공정을 이용해서 $2.5{\mu}m$ 두께의 전극을 형성하였다. 9GHz 부근에서의 전극구조 공진형상 때문에 변조특성이 제한 되었지만, 2.5GHz 까지는 큰 왜곡없이 변조특성이 관찰되었다. Ti : $LiNbO_3$ traveling-wave phase optical modulators at wavelength 1.3㎛ have been designed and fabricated, focusing on the optical waveguide and asymmetric coplanar electrode structure. To improve the phase-mismatch of traveling-wave ACPS electrode, the characteristic impedance, effective microwave index, and electrode loss have been presented as a function of geometric parameters including electrode and buffer layer thickness. Low-loss channel optical waveguides on $LiNbO_3$ were fabricated by the Ti diffusion method with $O_2$ water-vapor environment. $2.5{\mu}m$ thick electrode was successfully fabricated by double-spin image reversal process. Modulation bandwidth was limited by a resonance at 2.9 GHz and modulation bandwidth up to 2.5GHz was approxirnately measured.

양방향 고속 테이타 버스에 관한 연구

鄭洪植 홍익대학교 산업기술연구소 1993 産業技術 Vol.2 No.-

A useful termination scheme is presented for a high speed bi-directional ECL data bus which traverse a backplane. This scheme was simulated using microwave-SPICE, and is contrasted to the typical termination methods. The bus has multiple I/O ports due to system constraints, each load/driver has an unwanted stub and the network has no clear termination point. As an additional complication, the effect of backplane connector on signal integrity is considered. A generic connector model is presented which is useful in determining the magnitude of this effect. The final design constraints is the IC devices's DC drive capability of the circuit, which is limited to a minimum of 25 ohms. In deciding how to terminate a paticular network, several design parameters must be considered. The two most important are : DC drive capability of the source, and the characteristic impedance of the transmission line which carries the signal. In general, ECL system are designed with a characteristic impedance on all traces of between fifty and ninety ohms. In most cases, the drive capability of the source is something greater than 25ohms(the same system may have both 50 and 25 ohn drivers). Consequently, a general design rule for uni-directional networks is to terminate all networks in their characteristic impedance. In the bi-directional case, both parameters must be considered, DC drive capability, and Zo/Rt mismatch). If a circuit has a 25 ohm driver, and Zo of 50 ohms it should obviously be terminated at each end with 50 ohms. Each design criteria is satisfied. The interesting case is when the driver can drive no less than 50 ohms and the characteristic impedance is 50 ohms. If one were to terminate each end of the network with 50 ohms, there would be minimal reflections from the terminating resistor, however, the driver would be in an environment with too low a DC resistance, and would probably suffer noise problems due to the level shift.

Ti:LINbO₃ 채널 광도파로의 주기 분극반전 공정 개발에 관한 연구

鄭洪植 홍익대학교 산업기술연구소 2006 産業技術 Vol.16 No.-

A fabrication process of periodic electric field assisted poling of Ti-diffused channel waveguides in LiNbO_3 (Ti:PPLN) has been developed and improved using a periodically 180o phase inversion along y-axis. The zig for domain inversion and control program of poling current and charge has been devised. Pulse high voltage and duty cycle were adjusted based on the estimated current and charge required for poling inversion.

광대역 Mach-Zehnder 간섭형 광변조기 설계에 관한 연구

鄭洪植 홍익대학교 산업기술연구소 1994 産業技術 Vol.4 No.-

Broaband Mach-Zehnder interferometric optical modulators at wavelength 1.52㎛ have been designed based on the Ti-LinbO_3 Mach-Zehnder interferometer and coplanar waveguide(CPW) traveling-wave eletrode structure. The characteristic impedance effctive modulating-wave index electrode loss overlap factor and driving power for CPW have been derived as a function of geometric parameters including electrode and buffer layer thickness. The designed Mach-Zehnder inerfermeters were simulated utilizing BPM-CAD TOOL and CPW electrode structures including D.C bias portion were designed. The microwave characteristic values for CPW were calculated.

Film-Loaded 음향파 도파로를 이용한 Ti:LiNbO₃ 음향광학 파장가변 광 필터에 관한 연구

鄭洪植 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-

An optimum Hamming apodized acousto-optic tunable filter using SiO₂ film loaded acoustic waveguide with angular offset to the Ti:LiNbO₃ waveguide were fabricated. Insertion loss <7.1㏈ has been obtained and side-lobe of ∼19㏈ for ∼32㎽ RF driving power has been realized. A TE↔TM polarization mode convertible performance has been confirmed and a linear tuning rate of 8.1㎚/㎒ and a 3㏈ spectral width of ∼1.5㎚ were demonstrated.

송년특집-국가기간전산망 사업과 정보산업 육성

정홍식,Jeong, Hong-Sik 한국전자정보통신산업진흥회 1988 電子振興 Vol.8 No.12

Zn-Vapor 확산에 의한 Ti : LiTaO3 광도파로의 굴절율 증가에 관한 연구 ( Enhancement of refractive Index in Ti : LitaO3 Optical Waveguides by Zn-Vapor Diffusion )

정홍식,이두복 대한전자공학회 1990 대한전자공학회 학술대회 Vol.1990 No.5

FIDIC 건설표준계약에서 발주자 일방의 공사변경(variations)권한-준거법이 영국법인 상황을중심으로-

정홍식 국제거래법학회 2015 國際去來法硏究 Vol.24 No.1

The so called scope of the works, once defined within a construction contract, including the employer’s requirements, specifications, drawings and bills of quantity, may require various alterations to successfully adapt to circumstances and events which were not foreseen in detail. Typically construction contracts provide so called variation clauses allowing the employer unilaterally change the scope, sequence, method or design of the works. By this menas the contract is able to respond to the practical needs of all kinds of projects. In fact, variations to the works are almost inevitable, because of the fact that events and circumstances arise which may be beyond the control of the parties albeit also being caused by them. Thus, the reasons for variations can be manifold. Under a FIDIC contract, variations are covered by clause 13. The clause covers both the authority of the engineer and the employer as well as the procedures for work being added, omitted, or changed from the original contract, either by initiative of the contractor (value engineering) or the initiative of the engineer. Also the extent to which the agreement in terms of price and time for completion will be affected by variation orders is commonly stipulated in detail by the contract. FIDIC forms of contract distinguish between the effects of variations upon time and cost and provide different rules for claims as to extension of time and cost. This article covers in detail FIDIC variation and relevant clauses, including but not limited to concept, extent, and effect of employer’s unilateral variation right, formal requirement of the variation, distinction from site instruction and concessions, agency authority, its relation with demand guarantee, comparison with doctrines of frustration and changed circumstances. Further, this article explores what limitation and restriction can be imposed on employer in exercising such right to vary, including the right to omit a certain part of the works. 국제상사계약의 계약변경(modification)은 계약체결 이후 변경 당시 당사자들 간 합의에 의해 이루어진다. 이러한 형태는 ‘합의에 의한 내용변경’이다. 그런데 해외건설프로젝트에 서 계약변경의 일종인 공사변경(variation)이 발생하는데, 이는 당사자들 간 계약상 합의에 의해 공사도중 발주자가 일방적으로(unilateral) 공사변경권을 행사할 수 있도록 하는 점이 특징이다. 이러한 형태는 ‘합의에 유보된 일방적 변경권’이라 칭할 수 있다. FIDIC 건설표준계약에서 발주자가 공사변경 지시를 내리면 시공자는 그 지시를 따르도록 의무화하고 있으며, 대신 공사변경에 따라 공기에 영향을 미치면 공기연장을 부여받고 계약대금이 증액 될 시 추가공사비를 보상받는 점이 특색이다. 건설공사 도중 계약상 공사범위(scope of works)를 변경하거나 혹은 추가공사를 수행하는 경우는 비일비재하다. 거의 모든 공사에서 공사변경이 발생한다 해도 과언이 아니다. 때문에 국제건설계약 상 공사변경을 둘러싼 발주자와 시공자 간 분쟁은 빠지지 않는 쟁점이다. 이에 본고는 국내 건설사들이 해외건설에서 가장 많이 쓰게 되는 FIDIC 건설표준계약상의 공사변경 조문을 중심으로 그 개념정의부터 출발하여 공사변경 지시가 내려질 수 있는 범위와 형태, 그 지시의 효과 및 결과 등을 중점적으로 살펴본다. 그 다음 공사변경의 법적 성격을 비교법적으로 간략히 조명해 보고, 목적달성불능의 원칙(doctrine of frustration)과 사정변경 원칙과 구분되는 점은 무엇인지 설명한다. 마지막으로 발주자 일방의 공사변경 권한의 제한이 어떤 경우에 가능한지 살펴보고자 하는데, 특히 실무에서 크게 대두되고 있는 발주자의 일부 공사 생략(omission) 권한 및 이의 제한에 관해 살펴보면서 실무적인합의를 짚어본다. 상기 쟁점들에 대해서는 국제건설계약의 준거법으로 많이 지정되는 영국법 관점에서 분석하고 있다.